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1. 02:28 AM - Re: Re: RV-8 with O-540 in this months EAA Sport Aviation (Tom Martin)
2. 02:39 AM - Re: Re: RV-8 with O-540 in this months EAA Sport Aviation (Tom Martin)
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| Subject: | Re: RV-8 with O-540 in this months EAA Sport Aviation |
--> Rocket-List message posted by: "Tom Martin" <fairlea@execulink.com>
Mr. Baldwin is absolutely correct with his discussion of BSFC. I use this
concept whenever someone starts comparing their fuel burn per hour with my
rocket. Especially the "modern" engine guys. They will talk about how
efficient their engines are but when you break it down to lbs of fuel burned
per HP per hour it will be very close to my old lycoming. It always is
amazing to people how efficient the rocket is on a mpg basis compared with
other planes. This is no surprise if you use the BSFC concept and how clean
our airframes are.
gallons per hour. My engine is stock and I was flying at 800 feet above sea
level full throttle full rich. This yielded a speed of 208 knots or 240 mph.
I have about 500 hours of rocket time now in two planes, both of them with
stock engines. A very real and repeatable cross country number that I use
for flight planning is 175 knots at a fuel burn of 11.5 gph, wheels up to
wheels down. The power setting for this would be 22 to 23 inches and 2000 to
2100 rpm. I usually run 50 to 75 degrees rich of peak, yes I will run lean
of peak on occasion when I am high and using a low power setting. To run
properly lean of peak you need to have an engine monitor and you have to
know which cylinder peaks last. It takes a bit of fussing to get it right so
I usually do not bother
Tom Martin
-----Original Message-----
From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com]On Behalf Of
jamesbaldwin@attglobal.net
Subject: Re: Rocket-List: Re: RV-8 with O-540 in this months EAA Sport
Aviation
--> Rocket-List message posted by: jamesbaldwin@attglobal.net
Rocketeers and others -
The questions and rules of thumb given here regarding horsepower and fuel
consumption indicate to me you guys might like to understand how this thing
really works.
ALL engines, turbine or reciprocating, are very simple converter devices.
They convert fuel -- in the recip case gasoline, at 6.0 pounds per gallon
(auto fuel varies but is about 6.5 lbs/gal average) -- into useful work with
some undesirable byproducts -- heat and noise. I'm sure a lot of you
understand most of the heat energy lost in a recip goes out the exhaust pipe
with a smaller amount lost to the air through the cooling fins which exits
the cowl. Mechanical friction takes some too. This waste costs a major
portion of the energy prevalent in a pound of gasoline but still yields us
enough to turn our props.
In almost all common aircraft engines currently used in light planes, the
term BSFC (brake specific fuel consumption) falls within the range of 0.375
(rare) to 0.55 and the units are 'pounds per hour per horsepower'. In other
words, it takes about (average number) 0.45 pounds of fuel to produce one
horsepower for one hour. Remember this is pounds. If it is gallons it
would
be about .075 gallons.
Multiply gallons per hour times the weight of fuel per gallon to get
consumption in pounds per hour. Then multiply by the number of horses you
are using -- i.e. 200 horsepower engine at 75% power is 150 HP. If the BSFC
is .45 (pretty average but good number these days) then the hourly
consumption of fuel is .45 times 150 which equals 67.5 pounds per hour.
This
is equal to 11.25 gallons per hour if the fuel weighs 6.0 pounds per gallon.
If a guy leans his injected, flow optimized, blueprinted engine with great
fuel atomization (more complete burning of the fuel/air mixture) with
electronic ignition he might get down to either a lower burn per hour or
simply get more horsepower to the prop. An interesting note -- I always got
more range out of my Grumman Cheetah using auto gas because in some cases it
was as much as 8 or 9% heavier! More BTU's per pound, and engines don't
burn
gallons, they burn pounds!
I guarantee you these numbers are readily available to anyone using a decent
dyno with modern digital data acquisition. The engine used in the Voyager
was hitting some pretty low BSFC numbers because they used all the tricks --
high operating temps, low RPM, fuel injection, tuned exhaust, etc, etc. Our
Rocket engines with open exhaust (no mufflers), fuel injection, high CRs,
etc
should do pretty well except that we are all speed freaks and use a lot of
power playing around most of the time. When we get serious and do a X
country the numbers can be pretty good.
This was a simple, abbreviated version of horsepower estimation using fuel
flow. The bottom line is this: fuel consumption in gallons per hour times
the weight in pounds per gallon divided by the BSFC will give you how much
horsepower is being delivered to the prop. A dynamometer or torque
transducer is the only way to really know the actual HP number delivered to
the prop but the numbers from the factory for my Piper Twin Comanche with
fuel injected, open exhaust, 160 horsepower IO-320s ranges from .44 to .58
lbs/HP/hr. Get your calculators and have at it guys! JBB
p.s. I checked my calculations but if I made a mistake let me know.
"Boyd C. Braem" wrote:
> --> Rocket-List message posted by: "Boyd C. Braem" <bcbraem@comcast.net>
>
> Ron--
>
> Engines, like minds, are a terrible thing. The dyno report from LyCon
> (temp-60F, 29.84"Hg) at 2750 rpm showed 323 hp (so I lied about the
> 325!) at??? 25.6 gal/hr??? (maybe they meant 35.6) and a MAP of 27.51".
> However, down here in Venice, FL (which is 19' msl), on a good high
> pressure day, I generally run about 2.5" below ambient air pressure at
> the start of the take-off run and after I get some speed up my ram-air
> port reduces this to about 1.5" below ambient (non-filtered air)--fuel
> flow from my VM-1000, which has proved to be remarkably accurate, is
> usually around 35-36 gal/hr at 2800 rpm at sea-level take-off. One of
> the mechs at LyCon told me to divide the gal/hr flow at sea level, full
> power, by 0.11 to get an estimate of hp. I'm not sure how to correct
> that calculation for your msl altitude.
>
> With a "wide-body" -6, I generally get about 240 mph indicated at 75%
> (24/24) and around 260 at 2800 rpm, down where the deer and the buffalo
> roam. Max rate of climb with solo pilot is 4,300 fpm. I really love
> this airplane. Gross aerobatic weight is 1650 and max gross weight is
> 1900. Ready to fly empty weight is 1230.
>
> Boyd.
> Super-6
>
> Ron C wrote:
>
> >--> Rocket-List message posted by: "Ron C" <ronc@metropolisdesign.com>
> >
> >Whoa!!! Boyd!
> >
> >Chill out dude don't blow a base gasket. Remember " " "EXPERIMENTAL" "
> >" , get it?
> >
> >Hey, by the way, I noticed you list your Ly-Con 540 at 325 hp. Would you
> >mind listing whats been done to that bad boy and at what settings your
> >getting that much power? I have a balanced 540 with 10 to ones and have
> >been wondering how much it actually puts out- it has not been dynoed. At
> >full blow im doing 250 at 5,500 msl
> >
> >Thanks
> >
> >Ron Carter
> >HRII #49
> >335 ttsn
> >
> >
> >
> >
> >
> >
> >
>
Message 2
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| Subject: | Re: RV-8 with O-540 in this months EAA Sport Aviation |
--> Rocket-List message posted by: "Tom Martin" <fairlea@execulink.com>
Guys
This sentence, "For your information while I was running in the Sun 100
I
was burning 24 gallons per hour" should lead paragraph two of my posting.
It was clipped in the transmission, my apologies.
Tom Martin
-----Original Message-----
From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com]On Behalf Of Tom Martin
Subject: RE: Rocket-List: Re: RV-8 with O-540 in this months EAA Sport
Aviation
--> Rocket-List message posted by: "Tom Martin" <fairlea@execulink.com>
Mr. Baldwin is absolutely correct with his discussion of BSFC. I use this
concept whenever someone starts comparing their fuel burn per hour with my
rocket. Especially the "modern" engine guys. They will talk about how
efficient their engines are but when you break it down to lbs of fuel burned
per HP per hour it will be very close to my old lycoming. It always is
amazing to people how efficient the rocket is on a mpg basis compared with
other planes. This is no surprise if you use the BSFC concept and how clean
our airframes are.
gallons per hour. My engine is stock and I was flying at 800 feet above sea
level full throttle full rich. This yielded a speed of 208 knots or 240 mph.
I have about 500 hours of rocket time now in two planes, both of them with
stock engines. A very real and repeatable cross country number that I use
for flight planning is 175 knots at a fuel burn of 11.5 gph, wheels up to
wheels down. The power setting for this would be 22 to 23 inches and 2000 to
2100 rpm. I usually run 50 to 75 degrees rich of peak, yes I will run lean
of peak on occasion when I am high and using a low power setting. To run
properly lean of peak you need to have an engine monitor and you have to
know which cylinder peaks last. It takes a bit of fussing to get it right so
I usually do not bother
Tom Martin
-----Original Message-----
From: owner-rocket-list-server@matronics.com
[mailto:owner-rocket-list-server@matronics.com]On Behalf Of
jamesbaldwin@attglobal.net
Subject: Re: Rocket-List: Re: RV-8 with O-540 in this months EAA Sport
Aviation
--> Rocket-List message posted by: jamesbaldwin@attglobal.net
Rocketeers and others -
The questions and rules of thumb given here regarding horsepower and fuel
consumption indicate to me you guys might like to understand how this thing
really works.
ALL engines, turbine or reciprocating, are very simple converter devices.
They convert fuel -- in the recip case gasoline, at 6.0 pounds per gallon
(auto fuel varies but is about 6.5 lbs/gal average) -- into useful work with
some undesirable byproducts -- heat and noise. I'm sure a lot of you
understand most of the heat energy lost in a recip goes out the exhaust pipe
with a smaller amount lost to the air through the cooling fins which exits
the cowl. Mechanical friction takes some too. This waste costs a major
portion of the energy prevalent in a pound of gasoline but still yields us
enough to turn our props.
In almost all common aircraft engines currently used in light planes, the
term BSFC (brake specific fuel consumption) falls within the range of 0.375
(rare) to 0.55 and the units are 'pounds per hour per horsepower'. In other
words, it takes about (average number) 0.45 pounds of fuel to produce one
horsepower for one hour. Remember this is pounds. If it is gallons it
would
be about .075 gallons.
Multiply gallons per hour times the weight of fuel per gallon to get
consumption in pounds per hour. Then multiply by the number of horses you
are using -- i.e. 200 horsepower engine at 75% power is 150 HP. If the BSFC
is .45 (pretty average but good number these days) then the hourly
consumption of fuel is .45 times 150 which equals 67.5 pounds per hour.
This
is equal to 11.25 gallons per hour if the fuel weighs 6.0 pounds per gallon.
If a guy leans his injected, flow optimized, blueprinted engine with great
fuel atomization (more complete burning of the fuel/air mixture) with
electronic ignition he might get down to either a lower burn per hour or
simply get more horsepower to the prop. An interesting note -- I always got
more range out of my Grumman Cheetah using auto gas because in some cases it
was as much as 8 or 9% heavier! More BTU's per pound, and engines don't
burn
gallons, they burn pounds!
I guarantee you these numbers are readily available to anyone using a decent
dyno with modern digital data acquisition. The engine used in the Voyager
was hitting some pretty low BSFC numbers because they used all the tricks --
high operating temps, low RPM, fuel injection, tuned exhaust, etc, etc. Our
Rocket engines with open exhaust (no mufflers), fuel injection, high CRs,
etc
should do pretty well except that we are all speed freaks and use a lot of
power playing around most of the time. When we get serious and do a X
country the numbers can be pretty good.
This was a simple, abbreviated version of horsepower estimation using fuel
flow. The bottom line is this: fuel consumption in gallons per hour times
the weight in pounds per gallon divided by the BSFC will give you how much
horsepower is being delivered to the prop. A dynamometer or torque
transducer is the only way to really know the actual HP number delivered to
the prop but the numbers from the factory for my Piper Twin Comanche with
fuel injected, open exhaust, 160 horsepower IO-320s ranges from .44 to .58
lbs/HP/hr. Get your calculators and have at it guys! JBB
p.s. I checked my calculations but if I made a mistake let me know.
"Boyd C. Braem" wrote:
> --> Rocket-List message posted by: "Boyd C. Braem" <bcbraem@comcast.net>
>
> Ron--
>
> Engines, like minds, are a terrible thing. The dyno report from LyCon
> (temp-60F, 29.84"Hg) at 2750 rpm showed 323 hp (so I lied about the
> 325!) at??? 25.6 gal/hr??? (maybe they meant 35.6) and a MAP of 27.51".
> However, down here in Venice, FL (which is 19' msl), on a good high
> pressure day, I generally run about 2.5" below ambient air pressure at
> the start of the take-off run and after I get some speed up my ram-air
> port reduces this to about 1.5" below ambient (non-filtered air)--fuel
> flow from my VM-1000, which has proved to be remarkably accurate, is
> usually around 35-36 gal/hr at 2800 rpm at sea-level take-off. One of
> the mechs at LyCon told me to divide the gal/hr flow at sea level, full
> power, by 0.11 to get an estimate of hp. I'm not sure how to correct
> that calculation for your msl altitude.
>
> With a "wide-body" -6, I generally get about 240 mph indicated at 75%
> (24/24) and around 260 at 2800 rpm, down where the deer and the buffalo
> roam. Max rate of climb with solo pilot is 4,300 fpm. I really love
> this airplane. Gross aerobatic weight is 1650 and max gross weight is
> 1900. Ready to fly empty weight is 1230.
>
> Boyd.
> Super-6
>
> Ron C wrote:
>
> >--> Rocket-List message posted by: "Ron C" <ronc@metropolisdesign.com>
> >
> >Whoa!!! Boyd!
> >
> >Chill out dude don't blow a base gasket. Remember " " "EXPERIMENTAL" "
> >" , get it?
> >
> >Hey, by the way, I noticed you list your Ly-Con 540 at 325 hp. Would you
> >mind listing whats been done to that bad boy and at what settings your
> >getting that much power? I have a balanced 540 with 10 to ones and have
> >been wondering how much it actually puts out- it has not been dynoed. At
> >full blow im doing 250 at 5,500 msl
> >
> >Thanks
> >
> >Ron Carter
> >HRII #49
> >335 ttsn
> >
> >
> >
> >
> >
> >
> >
>
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