---------------------------------------------------------- L29-List Digest Archive --- Total Messages Posted Sat 08/26/06: 14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 09:38 AM - AC Response (SD737@aol.com) 2. 09:39 AM - M701 AC Drive (SD737@aol.com) 3. 10:54 AM - Re: M701 AC Drive (Jean de Roubin) 4. 12:10 PM - hp equivalent? (David M.) 5. 01:41 PM - Re: hp equivalent? (Brian Colombo) 6. 01:48 PM - Re: hp equivalent? (Brian Colombo) 7. 01:56 PM - Re: hp equivalent? (Ernest Martinez) 8. 02:00 PM - Re: hp equivalent? (Ernest Martinez) 9. 03:25 PM - Re: hp equivalent? (Jorgen Nielsen) 10. 05:11 PM - Re: hp equivalent? (Gail Taylor) 11. 06:42 PM - Re: hp equivalent? (David M.) 12. 07:01 PM - Re: hp equivalent? (Brian Colombo) 13. 08:28 PM - Re: L29-List horsepower conversion (Gail Taylor) 14. 11:15 PM - Re: Re: L29-List horsepower conversion (Jean de Roubin) ________________________________ Message 1 _____________________________________ Time: 09:38:18 AM PST US From: SD737@aol.com Subject: L29-List: AC Response Hello Ernie, My name is Stacy Lawrence. I was asked to send you an email to let you know when my A/C application would be available for the L-29. I have already tested the unit that I built and it works perfectly. I'm currently installing it and will be using my jet to do any further R&D. I told Bob Schwarts about my approach and I'm under the impression that he and others may believe that it was as simple as taking a window unit apart and reassembling the components in the plane and converting D/C to A/C. This couldn't be farther from the truth. >From reading some of your posts, I can see that you have a good understanding of some of the potential problems with this application. Some of which are liquid migration, a special expansion valve, and critical line volume and balance of the high and low sides. Everything goes out the window as soon as you start adding length or changing the ID of any lines. I have solved all of these problems over the course of months of development and bench testing. I do plan to have these units available in the late fall after I've thoroughly tested it. Take care, Stacy ________________________________ Message 2 _____________________________________ Time: 09:39:22 AM PST US From: SD737@aol.com Subject: L29-List: M701 AC Drive There is no second power source on the M701 by design. I thought initially about trying to build a boss with a seal and drive spline opposite the generator but after looking at it further, I discovered that it was never intended to drive another component. Not only is it under built, but let's assume that an A/C compressor was mounted on that section of the drive and it locked up for some reason.....The spline or shaft drive collar would fail and the fuel pump would be lost. That's why I came to the conclusion that a stand-alone system would work the best and would not compromise safety. Stacy ________________________________ Message 3 _____________________________________ Time: 10:54:02 AM PST US From: Jean de Roubin Subject: Re: L29-List: M701 AC Drive There is a second source of power on my M701. As far as I remember, it is about 15 cms from the high pressure pump, exactly the same that the one for the HP. I think it was originally done for an hypothetic second HP pumps (as on Vampire DH-100 for exemple) Le 26 ao=FBt 06 =E0 06:39, SD737@aol.com a =E9crit : > There is no second power source on the M701 by design. I thought > initially about trying to build a boss with a seal and drive spline > opposite the generator but after looking at it further, I > discovered that it was never intended to drive another component. > Not only is it under built, but let's assume that an A/C compressor > was mounted on that section of the drive and it locked up for some > reason.....The spline or shaft drive collar would fail and the fuel > pump would be lost. That's why I came to the conclusion that a > stand-alone system would work the best and would not compromise > safety. Stacy > ________________________________ Message 4 _____________________________________ Time: 12:10:58 PM PST US From: "David M." Subject: L29-List: hp equivalent? --> L29-List message posted by: "David M." Looking for the horsepower equivalent for the l-29 engine. Anyone have an idea? Thanks, David M. ________________________________ Message 5 _____________________________________ Time: 01:41:52 PM PST US From: "Brian Colombo" Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" I believe the formula is for between 1.75-2hp per lb of thrust. I will look through my turbine books tonight and post the exact numbers ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 3:07 PM Subject: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > an idea? > > Thanks, > David M. > > ________________________________ Message 6 _____________________________________ Time: 01:48:50 PM PST US From: "Brian Colombo" Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" Convert Thrust to Horsepower ---------------------------------------------------------------------------- ---- Is it possible to covert between pounds of thrust and horsepower for an airplane engine? How is it done? - David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, Pashaee, Brad Hornsby One of the most frequent questions we receive concerns the difference between thrust and horsepower and how to convert between the two. The problem is that these quantities are not directly related, so it is not simple to convert one to the other. The dictionary defines thrust as a force or pressure exerted on an object, and it is typically measured in units of pounds (lb) or newtons (N). Power, however, is a measurement of work, which is defined as the amount of motion a force creates when it is exerted on a body over a certain amount of time. Power is typically measured in units of horsepower (hp) or kilowatts (kW). The most common equation used to relate these quantities is as follows. where P = power F = force d = distance t = time To understand what these definitions mean, let's consider a simple example. Say you had to move a heavy desk 10 ft (3 m) from one side of the room to another. You push on the desk with a force of 90 lb (400 N), but the desk doesn't budge. In this case, a force has been applied, but since the desk remains in the same place, you didn't perform any work. Now you ask a friend to help you, and he pushes on the desk with the same force as you. Your combined force of 180 lb (800 N) allows you to move the desk to its new location in half a minute (30 seconds). Based on the above equation, the power you and your friend generated to perform that work was 60 foot-pounds per second or 80 newton-meters per second. In the Metric system, the unit of a watt (W) is defined as a newton-meter per second, so the power it took to move the desk is 80 W or 0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is equivalent to 0.11 hp. In this case and this case only, we can say that a force of 180 lb converts to 0.11 hp. As we have seen, however, that conversion depends on the variables distance and time. If you and your friend used the same force to move the desk the same distance but it took only 15 seconds, the power would double to 0.22 hp (0.16 kW). We can also think of this equation in two slightly different ways. Some readers may recognize that the force multiplied by distance represents another quantity called torque (T), so we can say power is equivalent to the torque a system generates over time. Others may recognize the term distance over time as the definition of velocity (v), so we can also say that power is equivalent to the force it takes to move an object at a constant speed. It is these two forms of the power equation that are most applicable to aviation. For example, one of the common types of question we receive asks how to convert the pounds of thrust generated by the jet engine(s) on a particular plane into horsepower. The first factor we must consider is that the thrust figures provided for most planes are in "static" units. Consider for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. These four engines generate a total static force rating of 219,000 lb (973 kN). However, this force is measured by placing the engine on a device called a test stand. A simple test stand used for small rocket motors A simple propulsion test stand is conceptually no different than standing on a bathroom scale and measuring how much you weigh, or how much force you exert standing on the surface of the Earth. The stand is fixed to the ground and an engine is strapped onto it. When turned on, the engine pushes against a scale (or load cell) that measures how much force the engine produces. Since the engine doesn't actually move but is rigidly held in place, we say that the force measured by the stand is in static pounds, or newtons, of force. How much power does the 747's Pratt & Whitney engine produce? As we discussed earlier, a static engine does no work no matter how much thrust it produces because it results in no motion. We must instead focus our attention on a plane that is in motion. For example, our 747 typically cruises around 600 mph (970 km/h). However, we are faced with a new problem because the plane does not necessarily need every bit of its static thrust to fly at that speed. In fact, static thrust is really an ideal maximum amount of thrust that an engine can produce in a test environment. As discussed in a previous question about thrust ratings, any jet engine will produce less thrust in actual use than the static value. Furthermore, aircraft are equipped with throttles that allow a pilot to adjust the amount of thrust an engine produces. A good example is the SR-71 Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a combined static thrust of 65,000 lb (289 kN). Even though the Blackbird could reach speeds in excess of Mach 3, however, it actually needed very little of this thrust in cruise flight. Most of the thrust was required to accelerate through the speed of sound, but once at Mach 3, the SR-71 engines were throttled back to only 30% or so. The conclusion of this explanation is that in order to determine the power a jet creates in flight, we need to know the exact amount of thrust necessary to fly at a particular speed. We typically know the static thrust rating of an engine or the airspeed of a plane during flight, but the problem is that we usually don't know the amount of thrust that corresponds to a particular speed at a specific point in time. It is because of this disconnect that it is so difficult to calculate the power generated by the engines on a particular plane. Luckily, we do have access to data from a NASA report that does provide all the data we need to illustrate a sample case. The data is provided for a Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, only a quarter of its rated static thrust, to cruise at a velocity of 871 ft/s (265 m/s). Using the equations provided above, we calculate the power generated by the 747 to be 87,325 hp (65,100 kW). The NASA data also includes a few other planes, so let's compare the power generated by the subsonic 747 airliner to a supersonic fighter like the F-4 Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft (16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of force and speed equates to a power of 36,620 hp (27,310 kW). These examples illustrate how cumbersome it is to convert between thrust and power. However, you may be wondering why jet engines or rocket engines are rated in units of thrust but propeller-driven engines are rated in units of power. For example, the F119 turbofans used on the F-22 are rated at 35,000 lb (310 kN) of thrust each and one of the main liquid rocket engines of the Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the distinction? How a jet engine works The answer relates to the fundamental way in which each of these engines works. Turbojet, turbofan, and rocket engines all work by directly accelerating a fluid to produce a thrust force, so it is most straightforward to rate these engines in terms of the size of that force. A piston engine, turboprop, or turboshaft is designed to perform mechanical work that turns a shaft. In other words, the engine creates a torque, and we saw earlier that one of the forms of the power equation relates power to the amount of torque created over time. The shaft that such an engine turns is connected to a propeller, which is an aerodynamic device that converts that power into thrust. The engine itself doesn't produce the thrust, but it turns a propeller that does. Also, two engines that generate the same power may not necessarily result in the same thrust since one may use a more efficient propeller than the other. For these reasons, it is more logical to rate these kinds of engines in terms of the power they create since that is the most direct quantity they produce. How a turboprop or turboshaft engine works Based on what we have seen, you ought to have a better appreciation for why it is preferable to compare jet engines in terms of thrust rather than power and propeller-driven engines in terms of power rather than thrust. While the opposite can be done, the process of converting between power and thrust requires us to know or assume additional information that is usually difficult or awkward to estimate. - answer by Joe Yoon, 26 September 2004 ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 3:07 PM Subject: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > an idea? > > Thanks, > David M. > > ________________________________ Message 7 _____________________________________ Time: 01:56:01 PM PST US From: "Ernest Martinez" Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Ernest Martinez" In reciprocating engines the simple formula is HP=TORQUE x RPM. In order to determine the HP of the M701 you would need to measure the shaft torque of the engine then multiply by 15,400 which is the RPM at 100%. Without knowing the amount of torque (force) the engine can produce then you cannot determine HP. Ernie On 8/26/06, Brian Colombo wrote: > --> L29-List message posted by: "Brian Colombo" > > Convert Thrust to Horsepower > > > ---------------------------------------------------------------------------- > ---- > > > Is it possible to covert between pounds of thrust and horsepower for an > airplane engine? How is it done? > - David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, > Pashaee, Brad Hornsby > One of the most frequent questions we receive concerns the difference > between thrust and horsepower and how to convert between the two. The > problem is that these quantities are not directly related, so it is not > simple to convert one to the other. The dictionary defines thrust as a force > or pressure exerted on an object, and it is typically measured in units of > pounds (lb) or newtons (N). Power, however, is a measurement of work, which > is defined as the amount of motion a force creates when it is exerted on a > body over a certain amount of time. Power is typically measured in units of > horsepower (hp) or kilowatts (kW). The most common equation used to relate > these quantities is as follows. > > > where > > P = power > F = force > d = distance > t = time > To understand what these definitions mean, let's consider a simple example. > Say you had to move a heavy desk 10 ft (3 m) from one side of the room to > another. You push on the desk with a force of 90 lb (400 N), but the desk > doesn't budge. In this case, a force has been applied, but since the desk > remains in the same place, you didn't perform any work. Now you ask a friend > to help you, and he pushes on the desk with the same force as you. Your > combined force of 180 lb (800 N) allows you to move the desk to its new > location in half a minute (30 seconds). > Based on the above equation, the power you and your friend generated to > perform that work was 60 foot-pounds per second or 80 newton-meters per > second. In the Metric system, the unit of a watt (W) is defined as a > newton-meter per second, so the power it took to move the desk is 80 W or > 0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is > defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is > equivalent to 0.11 hp. In this case and this case only, we can say that a > force of 180 lb converts to 0.11 hp. As we have seen, however, that > conversion depends on the variables distance and time. If you and your > friend used the same force to move the desk the same distance but it took > only 15 seconds, the power would double to 0.22 hp (0.16 kW). > > We can also think of this equation in two slightly different ways. Some > readers may recognize that the force multiplied by distance represents > another quantity called torque (T), so we can say power is equivalent to the > torque a system generates over time. > > > Others may recognize the term distance over time as the definition of > velocity (v), so we can also say that power is equivalent to the force it > takes to move an object at a constant speed. > > > It is these two forms of the power equation that are most applicable to > aviation. For example, one of the common types of question we receive asks > how to convert the pounds of thrust generated by the jet engine(s) on a > particular plane into horsepower. The first factor we must consider is that > the thrust figures provided for most planes are in "static" units. Consider > for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. > These four engines generate a total static force rating of 219,000 lb (973 > kN). However, this force is measured by placing the engine on a device > called a test stand. > > > A simple test stand used for small rocket motors > A simple propulsion test stand is conceptually no different than standing on > a bathroom scale and measuring how much you weigh, or how much force you > exert standing on the surface of the Earth. The stand is fixed to the ground > and an engine is strapped onto it. When turned on, the engine pushes against > a scale (or load cell) that measures how much force the engine produces. > Since the engine doesn't actually move but is rigidly held in place, we say > that the force measured by the stand is in static pounds, or newtons, of > force. > > How much power does the 747's Pratt & Whitney engine produce? As we > discussed earlier, a static engine does no work no matter how much thrust it > produces because it results in no motion. We must instead focus our > attention on a plane that is in motion. For example, our 747 typically > cruises around 600 mph (970 km/h). However, we are faced with a new problem > because the plane does not necessarily need every bit of its static thrust > to fly at that speed. In fact, static thrust is really an ideal maximum > amount of thrust that an engine can produce in a test environment. As > discussed in a previous question about thrust ratings, any jet engine will > produce less thrust in actual use than the static value. > > Furthermore, aircraft are equipped with throttles that allow a pilot to > adjust the amount of thrust an engine produces. A good example is the SR-71 > Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a > combined static thrust of 65,000 lb (289 kN). Even though the Blackbird > could reach speeds in excess of Mach 3, however, it actually needed very > little of this thrust in cruise flight. Most of the thrust was required to > accelerate through the speed of sound, but once at Mach 3, the SR-71 engines > were throttled back to only 30% or so. > > The conclusion of this explanation is that in order to determine the power a > jet creates in flight, we need to know the exact amount of thrust necessary > to fly at a particular speed. We typically know the static thrust rating of > an engine or the airspeed of a plane during flight, but the problem is that > we usually don't know the amount of thrust that corresponds to a particular > speed at a specific point in time. It is because of this disconnect that it > is so difficult to calculate the power generated by the engines on a > particular plane. > > Luckily, we do have access to data from a NASA report that does provide all > the data we need to illustrate a sample case. The data is provided for a > Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this > example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, > only a quarter of its rated static thrust, to cruise at a velocity of 871 > ft/s (265 m/s). Using the equations provided above, we calculate the power > generated by the 747 to be 87,325 hp (65,100 kW). > > The NASA data also includes a few other planes, so let's compare the power > generated by the subsonic 747 airliner to a supersonic fighter like the F-4 > Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft > (16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) > of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of > force and speed equates to a power of 36,620 hp (27,310 kW). > > These examples illustrate how cumbersome it is to convert between thrust and > power. However, you may be wondering why jet engines or rocket engines are > rated in units of thrust but propeller-driven engines are rated in units of > power. For example, the F119 turbofans used on the F-22 are rated at 35,000 > lb (310 kN) of thrust each and one of the main liquid rocket engines of the > Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a > turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston > engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the > distinction? > > > How a jet engine works > The answer relates to the fundamental way in which each of these engines > works. Turbojet, turbofan, and rocket engines all work by directly > accelerating a fluid to produce a thrust force, so it is most > straightforward to rate these engines in terms of the size of that force. A > piston engine, turboprop, or turboshaft is designed to perform mechanical > work that turns a shaft. In other words, the engine creates a torque, and we > saw earlier that one of the forms of the power equation relates power to the > amount of torque created over time. The shaft that such an engine turns is > connected to a propeller, which is an aerodynamic device that converts that > power into thrust. The engine itself doesn't produce the thrust, but it > turns a propeller that does. Also, two engines that generate the same power > may not necessarily result in the same thrust since one may use a more > efficient propeller than the other. For these reasons, it is more logical to > rate these kinds of engines in terms of the power they create since that is > the most direct quantity they produce. > > > How a turboprop or turboshaft engine works > Based on what we have seen, you ought to have a better appreciation for why > it is preferable to compare jet engines in terms of thrust rather than power > and propeller-driven engines in terms of power rather than thrust. While the > opposite can be done, the process of converting between power and thrust > requires us to know or assume additional information that is usually > difficult or awkward to estimate. > - answer by Joe Yoon, 26 September 2004 > > ----- Original Message ----- > From: "David M." > To: > Sent: Saturday, August 26, 2006 3:07 PM > Subject: L29-List: hp equivalent? > > > > --> L29-List message posted by: "David M." > > > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > > an idea? > > > > Thanks, > > David M. > > > > > > > > > > ________________________________ Message 8 _____________________________________ Time: 02:00:36 PM PST US From: "Ernest Martinez" Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Ernest Martinez" One caveat, I was referring to shaft horsepoewer. Another way to get a rough figure is to determine the amount of Power the engine produces in KW and convert to HP, I beleive the KW rating is mentioned in the manuals.. Ernie On 8/26/06, Ernest Martinez wrote: > In reciprocating engines the simple formula is HP=TORQUE x RPM. In > order to determine the HP of the M701 you would need to measure the > shaft torque of the engine then multiply by 15,400 which is the RPM at > 100%. Without knowing the amount of torque (force) the engine can > produce then you cannot determine HP. > > Ernie > > On 8/26/06, Brian Colombo wrote: > > --> L29-List message posted by: "Brian Colombo" > > > > Convert Thrust to Horsepower > > > > > > ---------------------------------------------------------------------------- > > ---- > > > > > > Is it possible to covert between pounds of thrust and horsepower for an > > airplane engine? How is it done? > > - David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, > > Pashaee, Brad Hornsby > > One of the most frequent questions we receive concerns the difference > > between thrust and horsepower and how to convert between the two. The > > problem is that these quantities are not directly related, so it is not > > simple to convert one to the other. The dictionary defines thrust as a force > > or pressure exerted on an object, and it is typically measured in units of > > pounds (lb) or newtons (N). Power, however, is a measurement of work, which > > is defined as the amount of motion a force creates when it is exerted on a > > body over a certain amount of time. Power is typically measured in units of > > horsepower (hp) or kilowatts (kW). The most common equation used to relate > > these quantities is as follows. > > > > > > where > > > > P = power > > F = force > > d = distance > > t = time > > To understand what these definitions mean, let's consider a simple example. > > Say you had to move a heavy desk 10 ft (3 m) from one side of the room to > > another. You push on the desk with a force of 90 lb (400 N), but the desk > > doesn't budge. In this case, a force has been applied, but since the desk > > remains in the same place, you didn't perform any work. Now you ask a friend > > to help you, and he pushes on the desk with the same force as you. Your > > combined force of 180 lb (800 N) allows you to move the desk to its new > > location in half a minute (30 seconds). > > Based on the above equation, the power you and your friend generated to > > perform that work was 60 foot-pounds per second or 80 newton-meters per > > second. In the Metric system, the unit of a watt (W) is defined as a > > newton-meter per second, so the power it took to move the desk is 80 W or > > 0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is > > defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is > > equivalent to 0.11 hp. In this case and this case only, we can say that a > > force of 180 lb converts to 0.11 hp. As we have seen, however, that > > conversion depends on the variables distance and time. If you and your > > friend used the same force to move the desk the same distance but it took > > only 15 seconds, the power would double to 0.22 hp (0.16 kW). > > > > We can also think of this equation in two slightly different ways. Some > > readers may recognize that the force multiplied by distance represents > > another quantity called torque (T), so we can say power is equivalent to the > > torque a system generates over time. > > > > > > > > Others may recognize the term distance over time as the definition of > > velocity (v), so we can also say that power is equivalent to the force it > > takes to move an object at a constant speed. > > > > > > > > It is these two forms of the power equation that are most applicable to > > aviation. For example, one of the common types of question we receive asks > > how to convert the pounds of thrust generated by the jet engine(s) on a > > particular plane into horsepower. The first factor we must consider is that > > the thrust figures provided for most planes are in "static" units. Consider > > for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. > > These four engines generate a total static force rating of 219,000 lb (973 > > kN). However, this force is measured by placing the engine on a device > > called a test stand. > > > > > > > > A simple test stand used for small rocket motors > > A simple propulsion test stand is conceptually no different than standing on > > a bathroom scale and measuring how much you weigh, or how much force you > > exert standing on the surface of the Earth. The stand is fixed to the ground > > and an engine is strapped onto it. When turned on, the engine pushes against > > a scale (or load cell) that measures how much force the engine produces. > > Since the engine doesn't actually move but is rigidly held in place, we say > > that the force measured by the stand is in static pounds, or newtons, of > > force. > > > > How much power does the 747's Pratt & Whitney engine produce? As we > > discussed earlier, a static engine does no work no matter how much thrust it > > produces because it results in no motion. We must instead focus our > > attention on a plane that is in motion. For example, our 747 typically > > cruises around 600 mph (970 km/h). However, we are faced with a new problem > > because the plane does not necessarily need every bit of its static thrust > > to fly at that speed. In fact, static thrust is really an ideal maximum > > amount of thrust that an engine can produce in a test environment. As > > discussed in a previous question about thrust ratings, any jet engine will > > produce less thrust in actual use than the static value. > > > > Furthermore, aircraft are equipped with throttles that allow a pilot to > > adjust the amount of thrust an engine produces. A good example is the SR-71 > > Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a > > combined static thrust of 65,000 lb (289 kN). Even though the Blackbird > > could reach speeds in excess of Mach 3, however, it actually needed very > > little of this thrust in cruise flight. Most of the thrust was required to > > accelerate through the speed of sound, but once at Mach 3, the SR-71 engines > > were throttled back to only 30% or so. > > > > The conclusion of this explanation is that in order to determine the power a > > jet creates in flight, we need to know the exact amount of thrust necessary > > to fly at a particular speed. We typically know the static thrust rating of > > an engine or the airspeed of a plane during flight, but the problem is that > > we usually don't know the amount of thrust that corresponds to a particular > > speed at a specific point in time. It is because of this disconnect that it > > is so difficult to calculate the power generated by the engines on a > > particular plane. > > > > Luckily, we do have access to data from a NASA report that does provide all > > the data we need to illustrate a sample case. The data is provided for a > > Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this > > example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, > > only a quarter of its rated static thrust, to cruise at a velocity of 871 > > ft/s (265 m/s). Using the equations provided above, we calculate the power > > generated by the 747 to be 87,325 hp (65,100 kW). > > > > The NASA data also includes a few other planes, so let's compare the power > > generated by the subsonic 747 airliner to a supersonic fighter like the F-4 > > Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft > > (16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) > > of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of > > force and speed equates to a power of 36,620 hp (27,310 kW). > > > > These examples illustrate how cumbersome it is to convert between thrust and > > power. However, you may be wondering why jet engines or rocket engines are > > rated in units of thrust but propeller-driven engines are rated in units of > > power. For example, the F119 turbofans used on the F-22 are rated at 35,000 > > lb (310 kN) of thrust each and one of the main liquid rocket engines of the > > Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a > > turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston > > engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the > > distinction? > > > > > > > > How a jet engine works > > The answer relates to the fundamental way in which each of these engines > > works. Turbojet, turbofan, and rocket engines all work by directly > > accelerating a fluid to produce a thrust force, so it is most > > straightforward to rate these engines in terms of the size of that force. A > > piston engine, turboprop, or turboshaft is designed to perform mechanical > > work that turns a shaft. In other words, the engine creates a torque, and we > > saw earlier that one of the forms of the power equation relates power to the > > amount of torque created over time. The shaft that such an engine turns is > > connected to a propeller, which is an aerodynamic device that converts that > > power into thrust. The engine itself doesn't produce the thrust, but it > > turns a propeller that does. Also, two engines that generate the same power > > may not necessarily result in the same thrust since one may use a more > > efficient propeller than the other. For these reasons, it is more logical to > > rate these kinds of engines in terms of the power they create since that is > > the most direct quantity they produce. > > > > > > > > How a turboprop or turboshaft engine works > > Based on what we have seen, you ought to have a better appreciation for why > > it is preferable to compare jet engines in terms of thrust rather than power > > and propeller-driven engines in terms of power rather than thrust. While the > > opposite can be done, the process of converting between power and thrust > > requires us to know or assume additional information that is usually > > difficult or awkward to estimate. > > - answer by Joe Yoon, 26 September 2004 > > > > ----- Original Message ----- > > From: "David M." > > To: > > Sent: Saturday, August 26, 2006 3:07 PM > > Subject: L29-List: hp equivalent? > > > > > > > --> L29-List message posted by: "David M." > > > > > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > > > an idea? > > > > > > Thanks, > > > David M. > > > > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 9 _____________________________________ Time: 03:25:56 PM PST US From: "Jorgen Nielsen" Subject: RE: L29-List: hp equivalent? --> L29-List message posted by: "Jorgen Nielsen" I am not an engineer but the explanation below just does not work for me- what am I missing here? The example of the 747 and F4 use the NASA given thrust rating and the speed of the aircraft to determine thrust - what about the air density at 40000ft and 55000ft? That same 747 at say 5000ft at the same power setting would going at 1/4 of the speed, certainly nowhere near M0.9? -----Original Message----- From: owner-l29-list-server@matronics.com [mailto:owner-l29-list-server@matronics.com] On Behalf Of Brian Colombo Sent: 26 August 2006 10:48 PM Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" Convert Thrust to Horsepower ---------------------------------------------------------------------------- ---- Is it possible to covert between pounds of thrust and horsepower for an airplane engine? How is it done? - David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, Pashaee, Brad Hornsby One of the most frequent questions we receive concerns the difference between thrust and horsepower and how to convert between the two. The problem is that these quantities are not directly related, so it is not simple to convert one to the other. The dictionary defines thrust as a force or pressure exerted on an object, and it is typically measured in units of pounds (lb) or newtons (N). Power, however, is a measurement of work, which is defined as the amount of motion a force creates when it is exerted on a body over a certain amount of time. Power is typically measured in units of horsepower (hp) or kilowatts (kW). The most common equation used to relate these quantities is as follows. where P = power F = force d = distance t = time To understand what these definitions mean, let's consider a simple example. Say you had to move a heavy desk 10 ft (3 m) from one side of the room to another. You push on the desk with a force of 90 lb (400 N), but the desk doesn't budge. In this case, a force has been applied, but since the desk remains in the same place, you didn't perform any work. Now you ask a friend to help you, and he pushes on the desk with the same force as you. Your combined force of 180 lb (800 N) allows you to move the desk to its new location in half a minute (30 seconds). Based on the above equation, the power you and your friend generated to perform that work was 60 foot-pounds per second or 80 newton-meters per second. In the Metric system, the unit of a watt (W) is defined as a newton-meter per second, so the power it took to move the desk is 80 W or 0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is equivalent to 0.11 hp. In this case and this case only, we can say that a force of 180 lb converts to 0.11 hp. As we have seen, however, that conversion depends on the variables distance and time. If you and your friend used the same force to move the desk the same distance but it took only 15 seconds, the power would double to 0.22 hp (0.16 kW). We can also think of this equation in two slightly different ways. Some readers may recognize that the force multiplied by distance represents another quantity called torque (T), so we can say power is equivalent to the torque a system generates over time. Others may recognize the term distance over time as the definition of velocity (v), so we can also say that power is equivalent to the force it takes to move an object at a constant speed. It is these two forms of the power equation that are most applicable to aviation. For example, one of the common types of question we receive asks how to convert the pounds of thrust generated by the jet engine(s) on a particular plane into horsepower. The first factor we must consider is that the thrust figures provided for most planes are in "static" units. Consider for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. These four engines generate a total static force rating of 219,000 lb (973 kN). However, this force is measured by placing the engine on a device called a test stand. A simple test stand used for small rocket motors A simple propulsion test stand is conceptually no different than standing on a bathroom scale and measuring how much you weigh, or how much force you exert standing on the surface of the Earth. The stand is fixed to the ground and an engine is strapped onto it. When turned on, the engine pushes against a scale (or load cell) that measures how much force the engine produces. Since the engine doesn't actually move but is rigidly held in place, we say that the force measured by the stand is in static pounds, or newtons, of force. How much power does the 747's Pratt & Whitney engine produce? As we discussed earlier, a static engine does no work no matter how much thrust it produces because it results in no motion. We must instead focus our attention on a plane that is in motion. For example, our 747 typically cruises around 600 mph (970 km/h). However, we are faced with a new problem because the plane does not necessarily need every bit of its static thrust to fly at that speed. In fact, static thrust is really an ideal maximum amount of thrust that an engine can produce in a test environment. As discussed in a previous question about thrust ratings, any jet engine will produce less thrust in actual use than the static value. Furthermore, aircraft are equipped with throttles that allow a pilot to adjust the amount of thrust an engine produces. A good example is the SR-71 Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a combined static thrust of 65,000 lb (289 kN). Even though the Blackbird could reach speeds in excess of Mach 3, however, it actually needed very little of this thrust in cruise flight. Most of the thrust was required to accelerate through the speed of sound, but once at Mach 3, the SR-71 engines were throttled back to only 30% or so. The conclusion of this explanation is that in order to determine the power a jet creates in flight, we need to know the exact amount of thrust necessary to fly at a particular speed. We typically know the static thrust rating of an engine or the airspeed of a plane during flight, but the problem is that we usually don't know the amount of thrust that corresponds to a particular speed at a specific point in time. It is because of this disconnect that it is so difficult to calculate the power generated by the engines on a particular plane. Luckily, we do have access to data from a NASA report that does provide all the data we need to illustrate a sample case. The data is provided for a Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, only a quarter of its rated static thrust, to cruise at a velocity of 871 ft/s (265 m/s). Using the equations provided above, we calculate the power generated by the 747 to be 87,325 hp (65,100 kW). The NASA data also includes a few other planes, so let's compare the power generated by the subsonic 747 airliner to a supersonic fighter like the F-4 Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft (16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of force and speed equates to a power of 36,620 hp (27,310 kW). These examples illustrate how cumbersome it is to convert between thrust and power. However, you may be wondering why jet engines or rocket engines are rated in units of thrust but propeller-driven engines are rated in units of power. For example, the F119 turbofans used on the F-22 are rated at 35,000 lb (310 kN) of thrust each and one of the main liquid rocket engines of the Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the distinction? How a jet engine works The answer relates to the fundamental way in which each of these engines works. Turbojet, turbofan, and rocket engines all work by directly accelerating a fluid to produce a thrust force, so it is most straightforward to rate these engines in terms of the size of that force. A piston engine, turboprop, or turboshaft is designed to perform mechanical work that turns a shaft. In other words, the engine creates a torque, and we saw earlier that one of the forms of the power equation relates power to the amount of torque created over time. The shaft that such an engine turns is connected to a propeller, which is an aerodynamic device that converts that power into thrust. The engine itself doesn't produce the thrust, but it turns a propeller that does. Also, two engines that generate the same power may not necessarily result in the same thrust since one may use a more efficient propeller than the other. For these reasons, it is more logical to rate these kinds of engines in terms of the power they create since that is the most direct quantity they produce. How a turboprop or turboshaft engine works Based on what we have seen, you ought to have a better appreciation for why it is preferable to compare jet engines in terms of thrust rather than power and propeller-driven engines in terms of power rather than thrust. While the opposite can be done, the process of converting between power and thrust requires us to know or assume additional information that is usually difficult or awkward to estimate. - answer by Joe Yoon, 26 September 2004 ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 3:07 PM Subject: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > an idea? > > Thanks, > David M. > > ________________________________ Message 10 ____________________________________ Time: 05:11:08 PM PST US From: "Gail Taylor" Subject: RE: L29-List: hp equivalent? --> L29-List message posted by: "Gail Taylor" The formula is one pound of thrust equals one horsepower@375 mph inlet speed Pete taylor -----Original Message----- From: owner-l29-list-server@matronics.com [mailto:owner-l29-list-server@matronics.com] On Behalf Of Jorgen Nielsen Sent: Saturday, August 26, 2006 2:26 PM Subject: RE: L29-List: hp equivalent? --> L29-List message posted by: "Jorgen Nielsen" I am not an engineer but the explanation below just does not work for me- what am I missing here? The example of the 747 and F4 use the NASA given thrust rating and the speed of the aircraft to determine thrust - what about the air density at 40000ft and 55000ft? That same 747 at say 5000ft at the same power setting would going at 1/4 of the speed, certainly nowhere near M0.9? -----Original Message----- From: owner-l29-list-server@matronics.com [mailto:owner-l29-list-server@matronics.com] On Behalf Of Brian Colombo Sent: 26 August 2006 10:48 PM Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" Convert Thrust to Horsepower ---------------------------------------------------------------------------- ---- Is it possible to covert between pounds of thrust and horsepower for an airplane engine? How is it done? - David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, Pashaee, Brad Hornsby One of the most frequent questions we receive concerns the difference between thrust and horsepower and how to convert between the two. The problem is that these quantities are not directly related, so it is not simple to convert one to the other. The dictionary defines thrust as a force or pressure exerted on an object, and it is typically measured in units of pounds (lb) or newtons (N). Power, however, is a measurement of work, which is defined as the amount of motion a force creates when it is exerted on a body over a certain amount of time. Power is typically measured in units of horsepower (hp) or kilowatts (kW). The most common equation used to relate these quantities is as follows. where P = power F = force d = distance t = time To understand what these definitions mean, let's consider a simple example. Say you had to move a heavy desk 10 ft (3 m) from one side of the room to another. You push on the desk with a force of 90 lb (400 N), but the desk doesn't budge. In this case, a force has been applied, but since the desk remains in the same place, you didn't perform any work. Now you ask a friend to help you, and he pushes on the desk with the same force as you. Your combined force of 180 lb (800 N) allows you to move the desk to its new location in half a minute (30 seconds). Based on the above equation, the power you and your friend generated to perform that work was 60 foot-pounds per second or 80 newton-meters per second. In the Metric system, the unit of a watt (W) is defined as a newton-meter per second, so the power it took to move the desk is 80 W or 0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is equivalent to 0.11 hp. In this case and this case only, we can say that a force of 180 lb converts to 0.11 hp. As we have seen, however, that conversion depends on the variables distance and time. If you and your friend used the same force to move the desk the same distance but it took only 15 seconds, the power would double to 0.22 hp (0.16 kW). We can also think of this equation in two slightly different ways. Some readers may recognize that the force multiplied by distance represents another quantity called torque (T), so we can say power is equivalent to the torque a system generates over time. Others may recognize the term distance over time as the definition of velocity (v), so we can also say that power is equivalent to the force it takes to move an object at a constant speed. It is these two forms of the power equation that are most applicable to aviation. For example, one of the common types of question we receive asks how to convert the pounds of thrust generated by the jet engine(s) on a particular plane into horsepower. The first factor we must consider is that the thrust figures provided for most planes are in "static" units. Consider for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. These four engines generate a total static force rating of 219,000 lb (973 kN). However, this force is measured by placing the engine on a device called a test stand. A simple test stand used for small rocket motors A simple propulsion test stand is conceptually no different than standing on a bathroom scale and measuring how much you weigh, or how much force you exert standing on the surface of the Earth. The stand is fixed to the ground and an engine is strapped onto it. When turned on, the engine pushes against a scale (or load cell) that measures how much force the engine produces. Since the engine doesn't actually move but is rigidly held in place, we say that the force measured by the stand is in static pounds, or newtons, of force. How much power does the 747's Pratt & Whitney engine produce? As we discussed earlier, a static engine does no work no matter how much thrust it produces because it results in no motion. We must instead focus our attention on a plane that is in motion. For example, our 747 typically cruises around 600 mph (970 km/h). However, we are faced with a new problem because the plane does not necessarily need every bit of its static thrust to fly at that speed. In fact, static thrust is really an ideal maximum amount of thrust that an engine can produce in a test environment. As discussed in a previous question about thrust ratings, any jet engine will produce less thrust in actual use than the static value. Furthermore, aircraft are equipped with throttles that allow a pilot to adjust the amount of thrust an engine produces. A good example is the SR-71 Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a combined static thrust of 65,000 lb (289 kN). Even though the Blackbird could reach speeds in excess of Mach 3, however, it actually needed very little of this thrust in cruise flight. Most of the thrust was required to accelerate through the speed of sound, but once at Mach 3, the SR-71 engines were throttled back to only 30% or so. The conclusion of this explanation is that in order to determine the power a jet creates in flight, we need to know the exact amount of thrust necessary to fly at a particular speed. We typically know the static thrust rating of an engine or the airspeed of a plane during flight, but the problem is that we usually don't know the amount of thrust that corresponds to a particular speed at a specific point in time. It is because of this disconnect that it is so difficult to calculate the power generated by the engines on a particular plane. Luckily, we do have access to data from a NASA report that does provide all the data we need to illustrate a sample case. The data is provided for a Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, only a quarter of its rated static thrust, to cruise at a velocity of 871 ft/s (265 m/s). Using the equations provided above, we calculate the power generated by the 747 to be 87,325 hp (65,100 kW). The NASA data also includes a few other planes, so let's compare the power generated by the subsonic 747 airliner to a supersonic fighter like the F-4 Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft (16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of force and speed equates to a power of 36,620 hp (27,310 kW). These examples illustrate how cumbersome it is to convert between thrust and power. However, you may be wondering why jet engines or rocket engines are rated in units of thrust but propeller-driven engines are rated in units of power. For example, the F119 turbofans used on the F-22 are rated at 35,000 lb (310 kN) of thrust each and one of the main liquid rocket engines of the Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the distinction? How a jet engine works The answer relates to the fundamental way in which each of these engines works. Turbojet, turbofan, and rocket engines all work by directly accelerating a fluid to produce a thrust force, so it is most straightforward to rate these engines in terms of the size of that force. A piston engine, turboprop, or turboshaft is designed to perform mechanical work that turns a shaft. In other words, the engine creates a torque, and we saw earlier that one of the forms of the power equation relates power to the amount of torque created over time. The shaft that such an engine turns is connected to a propeller, which is an aerodynamic device that converts that power into thrust. The engine itself doesn't produce the thrust, but it turns a propeller that does. Also, two engines that generate the same power may not necessarily result in the same thrust since one may use a more efficient propeller than the other. For these reasons, it is more logical to rate these kinds of engines in terms of the power they create since that is the most direct quantity they produce. How a turboprop or turboshaft engine works Based on what we have seen, you ought to have a better appreciation for why it is preferable to compare jet engines in terms of thrust rather than power and propeller-driven engines in terms of power rather than thrust. While the opposite can be done, the process of converting between power and thrust requires us to know or assume additional information that is usually difficult or awkward to estimate. - answer by Joe Yoon, 26 September 2004 ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 3:07 PM Subject: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Looking for the horsepower equivalent for the l-29 engine. Anyone have > an idea? > > Thanks, > David M. > > ________________________________ Message 11 ____________________________________ Time: 06:42:12 PM PST US From: "David M." Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "David M." Brian, I understand all that. That's why I asked for "equivalent." :) I don't know the thrust rating for the normal L-29 engine nor can I remember the formula for the conversion. One makes lots of standard assumptions during the conversion process. I just was hoping someone knew the values off the top of their head. Thanks, David M. Brian Colombo wrote: >--> L29-List message posted by: "Brian Colombo" > >Convert Thrust to Horsepower > > >---------------------------------------------------------------------------- >---- > > >Is it possible to covert between pounds of thrust and horsepower for an >airplane engine? How is it done? >- David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, >Pashaee, Brad Hornsby >One of the most frequent questions we receive concerns the difference >between thrust and horsepower and how to convert between the two. The >problem is that these quantities are not directly related, so it is not >simple to convert one to the other. The dictionary defines thrust as a force >or pressure exerted on an object, and it is typically measured in units of >pounds (lb) or newtons (N). Power, however, is a measurement of work, which >is defined as the amount of motion a force creates when it is exerted on a >body over a certain amount of time. Power is typically measured in units of >horsepower (hp) or kilowatts (kW). The most common equation used to relate >these quantities is as follows. > > >where > >P = power >F = force >d = distance >t = time >To understand what these definitions mean, let's consider a simple example. >Say you had to move a heavy desk 10 ft (3 m) from one side of the room to >another. You push on the desk with a force of 90 lb (400 N), but the desk >doesn't budge. In this case, a force has been applied, but since the desk >remains in the same place, you didn't perform any work. Now you ask a friend >to help you, and he pushes on the desk with the same force as you. Your >combined force of 180 lb (800 N) allows you to move the desk to its new >location in half a minute (30 seconds). >Based on the above equation, the power you and your friend generated to >perform that work was 60 foot-pounds per second or 80 newton-meters per >second. In the Metric system, the unit of a watt (W) is defined as a >newton-meter per second, so the power it took to move the desk is 80 W or >0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is >defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is >equivalent to 0.11 hp. In this case and this case only, we can say that a >force of 180 lb converts to 0.11 hp. As we have seen, however, that >conversion depends on the variables distance and time. If you and your >friend used the same force to move the desk the same distance but it took >only 15 seconds, the power would double to 0.22 hp (0.16 kW). > >We can also think of this equation in two slightly different ways. Some >readers may recognize that the force multiplied by distance represents >another quantity called torque (T), so we can say power is equivalent to the >torque a system generates over time. > > >Others may recognize the term distance over time as the definition of >velocity (v), so we can also say that power is equivalent to the force it >takes to move an object at a constant speed. > > >It is these two forms of the power equation that are most applicable to >aviation. For example, one of the common types of question we receive asks >how to convert the pounds of thrust generated by the jet engine(s) on a >particular plane into horsepower. The first factor we must consider is that >the thrust figures provided for most planes are in "static" units. Consider >for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. >These four engines generate a total static force rating of 219,000 lb (973 >kN). However, this force is measured by placing the engine on a device >called a test stand. > > >A simple test stand used for small rocket motors >A simple propulsion test stand is conceptually no different than standing on >a bathroom scale and measuring how much you weigh, or how much force you >exert standing on the surface of the Earth. The stand is fixed to the ground >and an engine is strapped onto it. When turned on, the engine pushes against >a scale (or load cell) that measures how much force the engine produces. >Since the engine doesn't actually move but is rigidly held in place, we say >that the force measured by the stand is in static pounds, or newtons, of >force. > >How much power does the 747's Pratt & Whitney engine produce? As we >discussed earlier, a static engine does no work no matter how much thrust it >produces because it results in no motion. We must instead focus our >attention on a plane that is in motion. For example, our 747 typically >cruises around 600 mph (970 km/h). However, we are faced with a new problem >because the plane does not necessarily need every bit of its static thrust >to fly at that speed. In fact, static thrust is really an ideal maximum >amount of thrust that an engine can produce in a test environment. As >discussed in a previous question about thrust ratings, any jet engine will >produce less thrust in actual use than the static value. > >Furthermore, aircraft are equipped with throttles that allow a pilot to >adjust the amount of thrust an engine produces. A good example is the SR-71 >Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a >combined static thrust of 65,000 lb (289 kN). Even though the Blackbird >could reach speeds in excess of Mach 3, however, it actually needed very >little of this thrust in cruise flight. Most of the thrust was required to >accelerate through the speed of sound, but once at Mach 3, the SR-71 engines >were throttled back to only 30% or so. > >The conclusion of this explanation is that in order to determine the power a >jet creates in flight, we need to know the exact amount of thrust necessary >to fly at a particular speed. We typically know the static thrust rating of >an engine or the airspeed of a plane during flight, but the problem is that >we usually don't know the amount of thrust that corresponds to a particular >speed at a specific point in time. It is because of this disconnect that it >is so difficult to calculate the power generated by the engines on a >particular plane. > >Luckily, we do have access to data from a NASA report that does provide all >the data we need to illustrate a sample case. The data is provided for a >Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this >example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, >only a quarter of its rated static thrust, to cruise at a velocity of 871 >ft/s (265 m/s). Using the equations provided above, we calculate the power >generated by the 747 to be 87,325 hp (65,100 kW). > >The NASA data also includes a few other planes, so let's compare the power >generated by the subsonic 747 airliner to a supersonic fighter like the F-4 >Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft >(16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) >of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of >force and speed equates to a power of 36,620 hp (27,310 kW). > >These examples illustrate how cumbersome it is to convert between thrust and >power. However, you may be wondering why jet engines or rocket engines are >rated in units of thrust but propeller-driven engines are rated in units of >power. For example, the F119 turbofans used on the F-22 are rated at 35,000 >lb (310 kN) of thrust each and one of the main liquid rocket engines of the >Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a >turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston >engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the >distinction? > > >How a jet engine works >The answer relates to the fundamental way in which each of these engines >works. Turbojet, turbofan, and rocket engines all work by directly >accelerating a fluid to produce a thrust force, so it is most >straightforward to rate these engines in terms of the size of that force. A >piston engine, turboprop, or turboshaft is designed to perform mechanical >work that turns a shaft. In other words, the engine creates a torque, and we >saw earlier that one of the forms of the power equation relates power to the >amount of torque created over time. The shaft that such an engine turns is >connected to a propeller, which is an aerodynamic device that converts that >power into thrust. The engine itself doesn't produce the thrust, but it >turns a propeller that does. Also, two engines that generate the same power >may not necessarily result in the same thrust since one may use a more >efficient propeller than the other. For these reasons, it is more logical to >rate these kinds of engines in terms of the power they create since that is >the most direct quantity they produce. > > >How a turboprop or turboshaft engine works >Based on what we have seen, you ought to have a better appreciation for why >it is preferable to compare jet engines in terms of thrust rather than power >and propeller-driven engines in terms of power rather than thrust. While the >opposite can be done, the process of converting between power and thrust >requires us to know or assume additional information that is usually >difficult or awkward to estimate. >- answer by Joe Yoon, 26 September 2004 > >----- Original Message ----- >From: "David M." >To: >Sent: Saturday, August 26, 2006 3:07 PM >Subject: L29-List: hp equivalent? > > > > >>--> L29-List message posted by: "David M." >> >>Looking for the horsepower equivalent for the l-29 engine. Anyone have >>an idea? >> >>Thanks, >>David M. >> >> >> >> >> >> > > > > ________________________________ Message 12 ____________________________________ Time: 07:01:34 PM PST US From: "Brian Colombo" Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" david, the normal thrust of a l-29 engine at sea leval normal temp is around 1960. I converted a 1400hp t58 turboshaft engine into a 840lb of thrust turbo jet by removing the power turbine section, making some mods and building a tail cone. That being said a jfs 100 is a small 100hp turboshaft that can be converted into a 90lb of thrust turbo jet. I Dont believe there is one formula.... Many factors come into play. I have a m701 l-29 engine on a test stand I built and just ran it for the first time the other day, was really cool, I was trying to figure out a way to turn it into a turboshaft myself. I do have some books that better explain it, I will look it up and try to find a better ans for you. ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 9:39 PM Subject: Re: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Brian, I understand all that. That's why I asked for "equivalent." :) > > I don't know the thrust rating for the normal L-29 engine nor can I > remember the formula for the conversion. One makes lots of standard > assumptions during the conversion process. I just was hoping someone > knew the values off the top of their head. > > Thanks, > David M. > > > Brian Colombo wrote: > > >--> L29-List message posted by: "Brian Colombo" > > > >Convert Thrust to Horsepower > > > > > >--------------------------------------------------------------------------- - > >---- > > > > > >Is it possible to covert between pounds of thrust and horsepower for an > >airplane engine? How is it done? > >- David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, > >Pashaee, Brad Hornsby > >One of the most frequent questions we receive concerns the difference > >between thrust and horsepower and how to convert between the two. The > >problem is that these quantities are not directly related, so it is not > >simple to convert one to the other. The dictionary defines thrust as a force > >or pressure exerted on an object, and it is typically measured in units of > >pounds (lb) or newtons (N). Power, however, is a measurement of work, which > >is defined as the amount of motion a force creates when it is exerted on a > >body over a certain amount of time. Power is typically measured in units of > >horsepower (hp) or kilowatts (kW). The most common equation used to relate > >these quantities is as follows. > > > > > >where > > > >P = power > >F = force > >d = distance > >t = time > >To understand what these definitions mean, let's consider a simple example. > >Say you had to move a heavy desk 10 ft (3 m) from one side of the room to > >another. You push on the desk with a force of 90 lb (400 N), but the desk > >doesn't budge. In this case, a force has been applied, but since the desk > >remains in the same place, you didn't perform any work. Now you ask a friend > >to help you, and he pushes on the desk with the same force as you. Your > >combined force of 180 lb (800 N) allows you to move the desk to its new > >location in half a minute (30 seconds). > >Based on the above equation, the power you and your friend generated to > >perform that work was 60 foot-pounds per second or 80 newton-meters per > >second. In the Metric system, the unit of a watt (W) is defined as a > >newton-meter per second, so the power it took to move the desk is 80 W or > >0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is > >defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is > >equivalent to 0.11 hp. In this case and this case only, we can say that a > >force of 180 lb converts to 0.11 hp. As we have seen, however, that > >conversion depends on the variables distance and time. If you and your > >friend used the same force to move the desk the same distance but it took > >only 15 seconds, the power would double to 0.22 hp (0.16 kW). > > > >We can also think of this equation in two slightly different ways. Some > >readers may recognize that the force multiplied by distance represents > >another quantity called torque (T), so we can say power is equivalent to the > >torque a system generates over time. > > > > > > > >Others may recognize the term distance over time as the definition of > >velocity (v), so we can also say that power is equivalent to the force it > >takes to move an object at a constant speed. > > > > > > > >It is these two forms of the power equation that are most applicable to > >aviation. For example, one of the common types of question we receive asks > >how to convert the pounds of thrust generated by the jet engine(s) on a > >particular plane into horsepower. The first factor we must consider is that > >the thrust figures provided for most planes are in "static" units. Consider > >for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. > >These four engines generate a total static force rating of 219,000 lb (973 > >kN). However, this force is measured by placing the engine on a device > >called a test stand. > > > > > > > >A simple test stand used for small rocket motors > >A simple propulsion test stand is conceptually no different than standing on > >a bathroom scale and measuring how much you weigh, or how much force you > >exert standing on the surface of the Earth. The stand is fixed to the ground > >and an engine is strapped onto it. When turned on, the engine pushes against > >a scale (or load cell) that measures how much force the engine produces. > >Since the engine doesn't actually move but is rigidly held in place, we say > >that the force measured by the stand is in static pounds, or newtons, of > >force. > > > >How much power does the 747's Pratt & Whitney engine produce? As we > >discussed earlier, a static engine does no work no matter how much thrust it > >produces because it results in no motion. We must instead focus our > >attention on a plane that is in motion. For example, our 747 typically > >cruises around 600 mph (970 km/h). However, we are faced with a new problem > >because the plane does not necessarily need every bit of its static thrust > >to fly at that speed. In fact, static thrust is really an ideal maximum > >amount of thrust that an engine can produce in a test environment. As > >discussed in a previous question about thrust ratings, any jet engine will > >produce less thrust in actual use than the static value. > > > >Furthermore, aircraft are equipped with throttles that allow a pilot to > >adjust the amount of thrust an engine produces. A good example is the SR-71 > >Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a > >combined static thrust of 65,000 lb (289 kN). Even though the Blackbird > >could reach speeds in excess of Mach 3, however, it actually needed very > >little of this thrust in cruise flight. Most of the thrust was required to > >accelerate through the speed of sound, but once at Mach 3, the SR-71 engines > >were throttled back to only 30% or so. > > > >The conclusion of this explanation is that in order to determine the power a > >jet creates in flight, we need to know the exact amount of thrust necessary > >to fly at a particular speed. We typically know the static thrust rating of > >an engine or the airspeed of a plane during flight, but the problem is that > >we usually don't know the amount of thrust that corresponds to a particular > >speed at a specific point in time. It is because of this disconnect that it > >is so difficult to calculate the power generated by the engines on a > >particular plane. > > > >Luckily, we do have access to data from a NASA report that does provide all > >the data we need to illustrate a sample case. The data is provided for a > >Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this > >example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, > >only a quarter of its rated static thrust, to cruise at a velocity of 871 > >ft/s (265 m/s). Using the equations provided above, we calculate the power > >generated by the 747 to be 87,325 hp (65,100 kW). > > > >The NASA data also includes a few other planes, so let's compare the power > >generated by the subsonic 747 airliner to a supersonic fighter like the F-4 > >Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft > >(16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) > >of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of > >force and speed equates to a power of 36,620 hp (27,310 kW). > > > >These examples illustrate how cumbersome it is to convert between thrust and > >power. However, you may be wondering why jet engines or rocket engines are > >rated in units of thrust but propeller-driven engines are rated in units of > >power. For example, the F119 turbofans used on the F-22 are rated at 35,000 > >lb (310 kN) of thrust each and one of the main liquid rocket engines of the > >Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a > >turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston > >engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the > >distinction? > > > > > > > >How a jet engine works > >The answer relates to the fundamental way in which each of these engines > >works. Turbojet, turbofan, and rocket engines all work by directly > >accelerating a fluid to produce a thrust force, so it is most > >straightforward to rate these engines in terms of the size of that force. A > >piston engine, turboprop, or turboshaft is designed to perform mechanical > >work that turns a shaft. In other words, the engine creates a torque, and we > >saw earlier that one of the forms of the power equation relates power to the > >amount of torque created over time. The shaft that such an engine turns is > >connected to a propeller, which is an aerodynamic device that converts that > >power into thrust. The engine itself doesn't produce the thrust, but it > >turns a propeller that does. Also, two engines that generate the same power > >may not necessarily result in the same thrust since one may use a more > >efficient propeller than the other. For these reasons, it is more logical to > >rate these kinds of engines in terms of the power they create since that is > >the most direct quantity they produce. > > > > > > > >How a turboprop or turboshaft engine works > >Based on what we have seen, you ought to have a better appreciation for why > >it is preferable to compare jet engines in terms of thrust rather than power > >and propeller-driven engines in terms of power rather than thrust. While the > >opposite can be done, the process of converting between power and thrust > >requires us to know or assume additional information that is usually > >difficult or awkward to estimate. > >- answer by Joe Yoon, 26 September 2004 > > > >----- Original Message ----- > >From: "David M." > >To: > >Sent: Saturday, August 26, 2006 3:07 PM > >Subject: L29-List: hp equivalent? > > > > > > > > > >>--> L29-List message posted by: "David M." > >> > >>Looking for the horsepower equivalent for the l-29 engine. Anyone have > >>an idea? > >> > >>Thanks, > >>David M. > >> > >> > >> > >> > >> > >> > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 13 ____________________________________ Time: 08:28:04 PM PST US From: "Gail Taylor" Subject: L29-List: RE: L29-List horsepower conversion --> L29-List message posted by: "Gail Taylor" One pound of thrust equals one horsepower at 375 M.P.H. Pete Taylor -----Original Message----- From: owner-l29-list-server@matronics.com [mailto:owner-l29-list-server@matronics.com] On Behalf Of Brian Colombo Sent: Saturday, August 26, 2006 6:02 PM Subject: Re: L29-List: hp equivalent? --> L29-List message posted by: "Brian Colombo" david, the normal thrust of a l-29 engine at sea leval normal temp is around 1960. I converted a 1400hp t58 turboshaft engine into a 840lb of thrust turbo jet by removing the power turbine section, making some mods and building a tail cone. That being said a jfs 100 is a small 100hp turboshaft that can be converted into a 90lb of thrust turbo jet. I Dont believe there is one formula.... Many factors come into play. I have a m701 l-29 engine on a test stand I built and just ran it for the first time the other day, was really cool, I was trying to figure out a way to turn it into a turboshaft myself. I do have some books that better explain it, I will look it up and try to find a better ans for you. ----- Original Message ----- From: "David M." Sent: Saturday, August 26, 2006 9:39 PM Subject: Re: L29-List: hp equivalent? > --> L29-List message posted by: "David M." > > Brian, I understand all that. That's why I asked for "equivalent." :) > > I don't know the thrust rating for the normal L-29 engine nor can I > remember the formula for the conversion. One makes lots of standard > assumptions during the conversion process. I just was hoping someone > knew the values off the top of their head. > > Thanks, > David M. > > > Brian Colombo wrote: > > >--> L29-List message posted by: "Brian Colombo" > > > >Convert Thrust to Horsepower > > > > > >--------------------------------------------------------------------------- - > >---- > > > > > >Is it possible to covert between pounds of thrust and horsepower for an > >airplane engine? How is it done? > >- David, Michael Hickey, Danny Williamson, Diego Codagnone, John Thomas, > >Pashaee, Brad Hornsby > >One of the most frequent questions we receive concerns the difference > >between thrust and horsepower and how to convert between the two. The > >problem is that these quantities are not directly related, so it is not > >simple to convert one to the other. The dictionary defines thrust as a force > >or pressure exerted on an object, and it is typically measured in units of > >pounds (lb) or newtons (N). Power, however, is a measurement of work, which > >is defined as the amount of motion a force creates when it is exerted on a > >body over a certain amount of time. Power is typically measured in units of > >horsepower (hp) or kilowatts (kW). The most common equation used to relate > >these quantities is as follows. > > > > > >where > > > >P = power > >F = force > >d = distance > >t = time > >To understand what these definitions mean, let's consider a simple example. > >Say you had to move a heavy desk 10 ft (3 m) from one side of the room to > >another. You push on the desk with a force of 90 lb (400 N), but the desk > >doesn't budge. In this case, a force has been applied, but since the desk > >remains in the same place, you didn't perform any work. Now you ask a friend > >to help you, and he pushes on the desk with the same force as you. Your > >combined force of 180 lb (800 N) allows you to move the desk to its new > >location in half a minute (30 seconds). > >Based on the above equation, the power you and your friend generated to > >perform that work was 60 foot-pounds per second or 80 newton-meters per > >second. In the Metric system, the unit of a watt (W) is defined as a > >newton-meter per second, so the power it took to move the desk is 80 W or > >0.08 kW. The English system equivalent of a watt is horsepower, and 1 hp is > >defined as being equal to 550 ft-lb/s. In other words, our 60 ft-lb/s is > >equivalent to 0.11 hp. In this case and this case only, we can say that a > >force of 180 lb converts to 0.11 hp. As we have seen, however, that > >conversion depends on the variables distance and time. If you and your > >friend used the same force to move the desk the same distance but it took > >only 15 seconds, the power would double to 0.22 hp (0.16 kW). > > > >We can also think of this equation in two slightly different ways. Some > >readers may recognize that the force multiplied by distance represents > >another quantity called torque (T), so we can say power is equivalent to the > >torque a system generates over time. > > > > > > > >Others may recognize the term distance over time as the definition of > >velocity (v), so we can also say that power is equivalent to the force it > >takes to move an object at a constant speed. > > > > > > > >It is these two forms of the power equation that are most applicable to > >aviation. For example, one of the common types of question we receive asks > >how to convert the pounds of thrust generated by the jet engine(s) on a > >particular plane into horsepower. The first factor we must consider is that > >the thrust figures provided for most planes are in "static" units. Consider > >for a moment the Boeing 747-200 with its Pratt & Whitney JT9D turbofans. > >These four engines generate a total static force rating of 219,000 lb (973 > >kN). However, this force is measured by placing the engine on a device > >called a test stand. > > > > > > > >A simple test stand used for small rocket motors > >A simple propulsion test stand is conceptually no different than standing on > >a bathroom scale and measuring how much you weigh, or how much force you > >exert standing on the surface of the Earth. The stand is fixed to the ground > >and an engine is strapped onto it. When turned on, the engine pushes against > >a scale (or load cell) that measures how much force the engine produces. > >Since the engine doesn't actually move but is rigidly held in place, we say > >that the force measured by the stand is in static pounds, or newtons, of > >force. > > > >How much power does the 747's Pratt & Whitney engine produce? As we > >discussed earlier, a static engine does no work no matter how much thrust it > >produces because it results in no motion. We must instead focus our > >attention on a plane that is in motion. For example, our 747 typically > >cruises around 600 mph (970 km/h). However, we are faced with a new problem > >because the plane does not necessarily need every bit of its static thrust > >to fly at that speed. In fact, static thrust is really an ideal maximum > >amount of thrust that an engine can produce in a test environment. As > >discussed in a previous question about thrust ratings, any jet engine will > >produce less thrust in actual use than the static value. > > > >Furthermore, aircraft are equipped with throttles that allow a pilot to > >adjust the amount of thrust an engine produces. A good example is the SR-71 > >Blackbird equipped with Pratt & Whitney J58 turboramjets that produced a > >combined static thrust of 65,000 lb (289 kN). Even though the Blackbird > >could reach speeds in excess of Mach 3, however, it actually needed very > >little of this thrust in cruise flight. Most of the thrust was required to > >accelerate through the speed of sound, but once at Mach 3, the SR-71 engines > >were throttled back to only 30% or so. > > > >The conclusion of this explanation is that in order to determine the power a > >jet creates in flight, we need to know the exact amount of thrust necessary > >to fly at a particular speed. We typically know the static thrust rating of > >an engine or the airspeed of a plane during flight, but the problem is that > >we usually don't know the amount of thrust that corresponds to a particular > >speed at a specific point in time. It is because of this disconnect that it > >is so difficult to calculate the power generated by the engines on a > >particular plane. > > > >Luckily, we do have access to data from a NASA report that does provide all > >the data we need to illustrate a sample case. The data is provided for a > >Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this > >example, the aircraft's engines produce 55,145 lb (245,295 N) of thrust, > >only a quarter of its rated static thrust, to cruise at a velocity of 871 > >ft/s (265 m/s). Using the equations provided above, we calculate the power > >generated by the 747 to be 87,325 hp (65,100 kW). > > > >The NASA data also includes a few other planes, so let's compare the power > >generated by the subsonic 747 airliner to a supersonic fighter like the F-4 > >Phantom II. In this example, the F-4 cruises at Mach 1.8 at 55,000 ft > >(16,765 m). The aircraft's two turbojet engines produce 11,560 lb (51,430 N) > >of thrust at its cruise speed of 1,742 ft/s (531 m/s). This combination of > >force and speed equates to a power of 36,620 hp (27,310 kW). > > > >These examples illustrate how cumbersome it is to convert between thrust and > >power. However, you may be wondering why jet engines or rocket engines are > >rated in units of thrust but propeller-driven engines are rated in units of > >power. For example, the F119 turbofans used on the F-22 are rated at 35,000 > >lb (310 kN) of thrust each and one of the main liquid rocket engines of the > >Space Shuttle produces 418,000 lb (1,860 kN) at lift off. Meanwhile, a > >turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the piston > >engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the > >distinction? > > > > > > > >How a jet engine works > >The answer relates to the fundamental way in which each of these engines > >works. Turbojet, turbofan, and rocket engines all work by directly > >accelerating a fluid to produce a thrust force, so it is most > >straightforward to rate these engines in terms of the size of that force. A > >piston engine, turboprop, or turboshaft is designed to perform mechanical > >work that turns a shaft. In other words, the engine creates a torque, and we > >saw earlier that one of the forms of the power equation relates power to the > >amount of torque created over time. The shaft that such an engine turns is > >connected to a propeller, which is an aerodynamic device that converts that > >power into thrust. The engine itself doesn't produce the thrust, but it > >turns a propeller that does. Also, two engines that generate the same power > >may not necessarily result in the same thrust since one may use a more > >efficient propeller than the other. For these reasons, it is more logical to > >rate these kinds of engines in terms of the power they create since that is > >the most direct quantity they produce. > > > > > > > >How a turboprop or turboshaft engine works > >Based on what we have seen, you ought to have a better appreciation for why > >it is preferable to compare jet engines in terms of thrust rather than power > >and propeller-driven engines in terms of power rather than thrust. While the > >opposite can be done, the process of converting between power and thrust > >requires us to know or assume additional information that is usually > >difficult or awkward to estimate. > >- answer by Joe Yoon, 26 September 2004 > > > >----- Original Message ----- > >From: "David M." > >To: > >Sent: Saturday, August 26, 2006 3:07 PM > >Subject: L29-List: hp equivalent? > > > > > > > > > >>--> L29-List message posted by: "David M." > >> > >>Looking for the horsepower equivalent for the l-29 engine. Anyone have > >>an idea? > >> > >>Thanks, > >>David M. > >> > >> > >> > >> > >> > >> > > > > > > > > > > > > > > > > > > > > > > ________________________________ Message 14 ____________________________________ Time: 11:15:21 PM PST US From: Jean de Roubin Subject: Re: L29-List: RE: L29-List horsepower conversion --> L29-List message posted by: Jean de Roubin As well explain by some other people, you can speak of horsepower for a jet engine only with an associated speed. At maximum speed (Mach 0,75) in a low level, M701 is about 2500 horsepower if my memory is good about my L-29 rating in the tzech army. Le 26 aot 06 17:27, Gail Taylor a crit : > --> L29-List message posted by: "Gail Taylor" > > One pound of thrust equals one horsepower at 375 M.P.H. > > > Pete Taylor > > -----Original Message----- > From: owner-l29-list-server@matronics.com > [mailto:owner-l29-list-server@matronics.com] On Behalf Of Brian > Colombo > Sent: Saturday, August 26, 2006 6:02 PM > To: l29-list@matronics.com > Subject: Re: L29-List: hp equivalent? > > --> L29-List message posted by: "Brian Colombo" > > > david, the normal thrust of a l-29 engine at sea leval normal temp > is around > 1960. I converted a 1400hp t58 turboshaft engine into a 840lb of > thrust > turbo jet by removing the power turbine section, making some mods and > building a tail cone. That being said a jfs 100 is a small 100hp > turboshaft > that can be converted into a 90lb of thrust turbo jet. I Dont > believe there > is one formula.... Many factors come into play. I have a m701 l-29 > engine > on a test stand I built and just ran it for the first time the > other day, > was really cool, I was trying to figure out a way to turn it into a > turboshaft myself. I do have some books that better explain it, I > will look > it up and try to find a better ans for you. > ----- Original Message ----- > From: "David M." > To: > Sent: Saturday, August 26, 2006 9:39 PM > Subject: Re: L29-List: hp equivalent? > > >> --> L29-List message posted by: "David M." >> >> Brian, I understand all that. That's why I asked for >> "equivalent." :) >> >> I don't know the thrust rating for the normal L-29 engine nor can I >> remember the formula for the conversion. One makes lots of standard >> assumptions during the conversion process. I just was hoping someone >> knew the values off the top of their head. >> >> Thanks, >> David M. >> >> >> Brian Colombo wrote: >> >>> --> L29-List message posted by: "Brian Colombo" >>> >>> >>> Convert Thrust to Horsepower >>> >>> >> >> --------------------------------------------------------------------- >> ------ > - >>> ---- >>> >>> >>> Is it possible to covert between pounds of thrust and horsepower >>> for an >>> airplane engine? How is it done? >>> - David, Michael Hickey, Danny Williamson, Diego Codagnone, John >>> Thomas, >>> Pashaee, Brad Hornsby >>> One of the most frequent questions we receive concerns the >>> difference >>> between thrust and horsepower and how to convert between the two. >>> The >>> problem is that these quantities are not directly related, so it >>> is not >>> simple to convert one to the other. The dictionary defines thrust >>> as a > force >>> or pressure exerted on an object, and it is typically measured in >>> units > of >>> pounds (lb) or newtons (N). Power, however, is a measurement of >>> work, > which >>> is defined as the amount of motion a force creates when it is >>> exerted on > a >>> body over a certain amount of time. Power is typically measured >>> in units > of >>> horsepower (hp) or kilowatts (kW). The most common equation used to > relate >>> these quantities is as follows. >>> >>> >>> where >>> >>> P = power >>> F = force >>> d = distance >>> t = time >>> To understand what these definitions mean, let's consider a simple > example. >>> Say you had to move a heavy desk 10 ft (3 m) from one side of the >>> room to >>> another. You push on the desk with a force of 90 lb (400 N), but >>> the desk >>> doesn't budge. In this case, a force has been applied, but since >>> the desk >>> remains in the same place, you didn't perform any work. Now you >>> ask a > friend >>> to help you, and he pushes on the desk with the same force as >>> you. Your >>> combined force of 180 lb (800 N) allows you to move the desk to >>> its new >>> location in half a minute (30 seconds). >>> Based on the above equation, the power you and your friend >>> generated to >>> perform that work was 60 foot-pounds per second or 80 newton- >>> meters per >>> second. In the Metric system, the unit of a watt (W) is defined as a >>> newton-meter per second, so the power it took to move the desk is >>> 80 W or >>> 0.08 kW. The English system equivalent of a watt is horsepower, >>> and 1 hp > is >>> defined as being equal to 550 ft-lb/s. In other words, our 60 ft- >>> lb/s is >>> equivalent to 0.11 hp. In this case and this case only, we can >>> say that a >>> force of 180 lb converts to 0.11 hp. As we have seen, however, that >>> conversion depends on the variables distance and time. If you and >>> your >>> friend used the same force to move the desk the same distance but >>> it took >>> only 15 seconds, the power would double to 0.22 hp (0.16 kW). >>> >>> We can also think of this equation in two slightly different >>> ways. Some >>> readers may recognize that the force multiplied by distance >>> represents >>> another quantity called torque (T), so we can say power is >>> equivalent to > the >>> torque a system generates over time. >>> >>> >>> >>> Others may recognize the term distance over time as the >>> definition of >>> velocity (v), so we can also say that power is equivalent to the >>> force it >>> takes to move an object at a constant speed. >>> >>> >>> >>> It is these two forms of the power equation that are most >>> applicable to >>> aviation. For example, one of the common types of question we >>> receive > asks >>> how to convert the pounds of thrust generated by the jet engine >>> (s) on a >>> particular plane into horsepower. The first factor we must >>> consider is > that >>> the thrust figures provided for most planes are in "static" units. > Consider >>> for a moment the Boeing 747-200 with its Pratt & Whitney JT9D >>> turbofans. >>> These four engines generate a total static force rating of >>> 219,000 lb > (973 >>> kN). However, this force is measured by placing the engine on a >>> device >>> called a test stand. >>> >>> >>> >>> A simple test stand used for small rocket motors >>> A simple propulsion test stand is conceptually no different than >>> standing > on >>> a bathroom scale and measuring how much you weigh, or how much >>> force you >>> exert standing on the surface of the Earth. The stand is fixed to >>> the > ground >>> and an engine is strapped onto it. When turned on, the engine pushes > against >>> a scale (or load cell) that measures how much force the engine >>> produces. >>> Since the engine doesn't actually move but is rigidly held in >>> place, we > say >>> that the force measured by the stand is in static pounds, or >>> newtons, of >>> force. >>> >>> How much power does the 747's Pratt & Whitney engine produce? As we >>> discussed earlier, a static engine does no work no matter how >>> much thrust > it >>> produces because it results in no motion. We must instead focus our >>> attention on a plane that is in motion. For example, our 747 >>> typically >>> cruises around 600 mph (970 km/h). However, we are faced with a new > problem >>> because the plane does not necessarily need every bit of its static > thrust >>> to fly at that speed. In fact, static thrust is really an ideal >>> maximum >>> amount of thrust that an engine can produce in a test >>> environment. As >>> discussed in a previous question about thrust ratings, any jet >>> engine > will >>> produce less thrust in actual use than the static value. >>> >>> Furthermore, aircraft are equipped with throttles that allow a >>> pilot to >>> adjust the amount of thrust an engine produces. A good example is >>> the > SR-71 >>> Blackbird equipped with Pratt & Whitney J58 turboramjets that >>> produced a >>> combined static thrust of 65,000 lb (289 kN). Even though the >>> Blackbird >>> could reach speeds in excess of Mach 3, however, it actually >>> needed very >>> little of this thrust in cruise flight. Most of the thrust was >>> required > to >>> accelerate through the speed of sound, but once at Mach 3, the SR-71 > engines >>> were throttled back to only 30% or so. >>> >>> The conclusion of this explanation is that in order to determine the > power a >>> jet creates in flight, we need to know the exact amount of thrust > necessary >>> to fly at a particular speed. We typically know the static thrust >>> rating > of >>> an engine or the airspeed of a plane during flight, but the >>> problem is > that >>> we usually don't know the amount of thrust that corresponds to a > particular >>> speed at a specific point in time. It is because of this >>> disconnect that > it >>> is so difficult to calculate the power generated by the engines on a >>> particular plane. >>> >>> Luckily, we do have access to data from a NASA report that does >>> provide > all >>> the data we need to illustrate a sample case. The data is >>> provided for a >>> Boeing 747-200 cruising at Mach 0.9 at 40,000 ft (12,190 m). In this >>> example, the aircraft's engines produce 55,145 lb (245,295 N) of >>> thrust, >>> only a quarter of its rated static thrust, to cruise at a >>> velocity of 871 >>> ft/s (265 m/s). Using the equations provided above, we calculate the > power >>> generated by the 747 to be 87,325 hp (65,100 kW). >>> >>> The NASA data also includes a few other planes, so let's compare the > power >>> generated by the subsonic 747 airliner to a supersonic fighter >>> like the > F-4 >>> Phantom II. In this example, the F-4 cruises at Mach 1.8 at >>> 55,000 ft >>> (16,765 m). The aircraft's two turbojet engines produce 11,560 lb >>> (51,430 > N) >>> of thrust at its cruise speed of 1,742 ft/s (531 m/s). This >>> combination > of >>> force and speed equates to a power of 36,620 hp (27,310 kW). >>> >>> These examples illustrate how cumbersome it is to convert between >>> thrust > and >>> power. However, you may be wondering why jet engines or rocket >>> engines > are >>> rated in units of thrust but propeller-driven engines are rated >>> in units > of >>> power. For example, the F119 turbofans used on the F-22 are rated at > 35,000 >>> lb (310 kN) of thrust each and one of the main liquid rocket >>> engines of > the >>> Space Shuttle produces 418,000 lb (1,860 kN) at lift off. >>> Meanwhile, a >>> turboprop engine of a C-130 is rated at 4,508 hp (3,362 kW) and the > piston >>> engine of a Cessna 172 generates 180 hp (135 kW) of power. Why the >>> distinction? >>> >>> >>> >>> How a jet engine works >>> The answer relates to the fundamental way in which each of these >>> engines >>> works. Turbojet, turbofan, and rocket engines all work by directly >>> accelerating a fluid to produce a thrust force, so it is most >>> straightforward to rate these engines in terms of the size of >>> that force. > A >>> piston engine, turboprop, or turboshaft is designed to perform >>> mechanical >>> work that turns a shaft. In other words, the engine creates a >>> torque, and > we >>> saw earlier that one of the forms of the power equation relates >>> power to > the >>> amount of torque created over time. The shaft that such an engine >>> turns > is >>> connected to a propeller, which is an aerodynamic device that >>> converts > that >>> power into thrust. The engine itself doesn't produce the thrust, >>> but it >>> turns a propeller that does. Also, two engines that generate the >>> same > power >>> may not necessarily result in the same thrust since one may use a >>> more >>> efficient propeller than the other. For these reasons, it is more >>> logical > to >>> rate these kinds of engines in terms of the power they create >>> since that > is >>> the most direct quantity they produce. >>> >>> >>> >>> How a turboprop or turboshaft engine works >>> Based on what we have seen, you ought to have a better >>> appreciation for > why >>> it is preferable to compare jet engines in terms of thrust rather >>> than > power >>> and propeller-driven engines in terms of power rather than >>> thrust. While > the >>> opposite can be done, the process of converting between power and >>> thrust >>> requires us to know or assume additional information that is usually >>> difficult or awkward to estimate. >>> - answer by Joe Yoon, 26 September 2004 >>> >>> ----- Original Message ----- >>> From: "David M." >>> To: >>> Sent: Saturday, August 26, 2006 3:07 PM >>> Subject: L29-List: hp equivalent? >>> >>> >>> >>> >>>> --> L29-List message posted by: "David M." >>>> >>>> Looking for the horsepower equivalent for the l-29 engine. >>>> Anyone have >>>> an idea? >>>> >>>> Thanks, >>>> David M. >>>> >>>> >>>> >>>> >>>> >>>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >>> >> >> >> > >