---------------------------------------------------------- Kolb-List Digest Archive --- Total Messages Posted Fri 04/30/10: 9 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:08 AM - Re: Angle of Bank vs Stall Speed/Approach Technique (Thom Riddle) 2. 04:37 AM - Re: Angle of Bank vs Stall Speed (Richard Girard) 3. 05:07 AM - Re: Angle of Bank vs Stall Speed (Dana Hague) 4. 08:47 AM - Re: Angle of Bank vs Stall Speed (b young) 5. 11:19 AM - Nose down at higher speeds. (Gray, Mark) 6. 02:08 PM - Re: Nose down at higher speeds. (robert bean) 7. 04:53 PM - Re: Angle of Bank vs Stall Speed (The Kuffels) 8. 07:27 PM - Re: Nose down at higher speeds. (Eugene Zimmerman) 9. 09:07 PM - Re: Nose down at higher speeds. (Greg) ________________________________ Message 1 _____________________________________ Time: 04:08:22 AM PST US Subject: Kolb-List: Re: Angle of Bank vs Stall Speed/Approach Technique From: "Thom Riddle" The link is a video of a Zenith 701 or 750 using the "level" approach method that Tom described. http://www.youtube.com/watch?v=s0gXSk_f250 Note the ASI during landing and take-off. Unfortunately, you can't see the power/rpm setting nor hear the engine due to music and the commentary audio track. -------- Thom Riddle Buffalo, NY Kolb Slingshot SS-021 Jabiru 2200A #1574 Tennessee Prop 64x32 An ounce of action is worth a ton of theory. - Friedrich Engels Read this topic online here: http://forums.matronics.com/viewtopic.php?p=296275#296275 ________________________________ Message 2 _____________________________________ Time: 04:37:52 AM PST US Subject: Re: Kolb-List: Angle of Bank vs Stall Speed From: Richard Girard This always turns (pardon me) into such a lively discussion about angles, constant speeds and gee loads and then somebody finally says something like, "What will also happen is your rate of decent will increase" and we get to the true crux of the matter. Something had to give among all these constants and it seems to be that the ground will come up at a faster rate to smite thee. How about that. I read somewhere that there was a sign in the Curtiss Flying School office that said, "Flying is simple, to go up pull back on the stick. To come down, pull back farther". That was around 100 years ago and seems to be, amazingly enough, still true today. Rick On Thu, Apr 29, 2010 at 11:25 PM, The Kuffels wrote: > Dana said: > > << << In a coordinated turn, the stall speed increases as a function of > the > bank angle >> > > Correct. >> > > Not correct. This is only true in the special circumstance of maintaining > altitude, ie increasing total lift, aka load factor. The emphasis on this > without equal emphasis on the special circumstance is *why* pilots in the > stress of landing still stall by trying to increase their rate of turn with > rudder alone (uncoordinated flight) and/or pulling back (increasing load > factor). The certain antidote to this error is constant airspeed during > landing maneuvers. > > Once again, go up in the air and test my statements. I don't dispute > holding a constant airspeed in a turn will increase your rate of decent. > But we are not talking about turns which last for minutes or even more than > a few seconds. I strongly dispute the notion that any technique other > than constant airspeed and coordinated flight independent of (less than > aerobatic) bank angle is the proper way to avoid problems during the turn > from base to final, particularly in situations of no or steady power or > practicing same, which should be almost always. > > Boyd said: > > << I had given an example of a steep bank turn to emphasize the situation. > And my definition of 1 g plus is 1.01g and above. I am probably taking > things to literally. >> > > Not really. I wasn't worried about 1 g +/- 10% or so. The problem is the > emphasis on bank angle materially increasing stall speed (I call double a > material increase) without equal emphasis that the real cause is via > increased load factor, and that this doesn't apply in a descending turn has > resulted in pilots killing themselves year after year in the turn to final. > And the absolutely, positively sure way to not increase load factor in this > turn is constant airspeed. > > << Any time you turn a plane there is going to be more energy required. > And > you can trade the energy needed to turn by unloading the wings momentarily > and remain at a literal 1g . But as soon as the plane returns to a steady > state and you remain in a turn, greater than 1g will be required. >> > > This is not true. The lift vector on the wings has no idea what the > gravity vector is doing. Go up and set a bank angle of 20 degrees and > constant airspeed. You will find yourself in a steady state turn of 1 g. > What will also happen is your rate of decent will increase. But this decent > is not in a vacuum. The increase in your decent is actually slowed by the > air such that several full circles are easily possible.. I've demonstrated > this many times for people, even disbelieving fellow CFIs. (Are CFIs really > people?) Now when doing the same thing at 60 degree bank things get real > exciting very soon, even at only 1/4 circle, which may be Dana's point. But > my point is this fact doesn't apply to the problem, its cause or the proper > solution to avoid it. > > Tom Kuffel > > * > > > * > > ________________________________ Message 3 _____________________________________ Time: 05:07:51 AM PST US From: Dana Hague Subject: Re: Kolb-List: Angle of Bank vs Stall Speed At 12:25 AM 4/30/2010, The Kuffels wrote: >Dana said: > ><< << In a coordinated turn, the stall speed increases as a function of >the >bank angle >> > >Correct. >> > >Not correct. This is only true in the special circumstance of maintaining >altitude, ie increasing total lift, aka load factor. I see your point, but... it's correct if you're maintaining altitude, but it's _also_ correct for a constant rate of descent, i.e. no vertical acceleration... which isn't happening in your 1g turn. > The emphasis on this without equal emphasis on the special circumstance > is *why* pilots in the stress of landing still stall by trying to > increase their rate of turn with rudder alone (uncoordinated flight) > and/or pulling back (increasing load factor). The certain antidote to > this error is constant airspeed during landing maneuvers.... I don't > dispute holding a constant airspeed in a turn will increase your rate of > decent. But we are not talking about turns which last for minutes or > even more than a few seconds. I strongly dispute the notion that any > technique other than constant airspeed and coordinated flight independent > of (less than aerobatic) bank angle is the proper way to avoid problems > during the turn from base to final, particularly in situations of no or > steady power or practicing same, which should be almost always. OK. I'm not saying your technique isn't valid; I'm just speaking as an aeronautical engineer precisely defining the situation. In aero engineering most flight conditions, other than stability and control calculations, are analyzed steady state, which your 1G increasing rate of descent gliding turn is not. Letting the airplane slide (not slip; by "slide" I mean keeping the ball centered) out of a turn by letting the nose drop is indeed a good way to manage a gliding turn. Reducing the load factor also maintains energy since you're not holding high AOA which causes drag and slows you down even more. I simply take exception to the notion that all will be well if you maintain constant airspeed. You say that avoidance of steep bank angle kills pilots who, trying to avoid an accelerated stall, instead spin out of a skid, and that's true, but it's only one side of the problem. On the other side, believing that all will be OK if you only maintain a constant airspeed can also get you into trouble... if a pilot does a 60 degree bank at 1.3Vs and _doesn't_ back off on the stick and let the nose drop, he _will_ experience an accelerated stall, which can be just as bad as the stall out of a skid. So: Stall speed is a function of load factor, not (necessarily) bank angle. Load factor IS a function of bank angle, but only in coordinated, level or constant vertical speed, flight. -Dana -- Puritanism: the haunting fear that someone, somewhere, may be happy. ________________________________ Message 4 _____________________________________ Time: 08:47:11 AM PST US From: "b young" Subject: RE: Kolb-List: Angle of Bank vs Stall Speed This is not true. The lift vector on the wings has no idea what the gravity vector is doing. Go up and set a bank angle of 20 degrees and constant airspeed. You will find yourself in a steady state turn of 1 g. What will also happen is your rate of decent will increase. But this decent is not in a vacuum. The increase in your decent is actually slowed by the air such that several full circles are easily possible.. I've demonstrated this many times for people, even disbelieving fellow CFIs. (Are CFIs really people?) Now when doing the same thing at 60 degree bank things get real exciting very soon, even at only 1/4 circle, which may be Dana's point. But my point is this fact doesn't apply to the problem, its cause or the proper solution to avoid it. Tom Kuffel Tom you said "Now when doing the same thing at 60 degree bank things get real exciting very soon, even at only 1/4 circle," ok would you like to explain in further detail just how ex citing and in what way? Boyd ________________________________ Message 5 _____________________________________ Time: 11:19:01 AM PST US From: "Gray, Mark" Subject: Kolb-List: Nose down at higher speeds. Both myself and a buddy who fly a Firestar and a Twinstar have the same is sue, when we get to around 75 mph indicated the planes start to nose over a nd begin to get a strange shuffling feel as if the wings are alternately sh uffling forward, kind of a tail wag maneuver. This continues to become more pronounced if we allow the speed to increase and it becomes necessary to a pply substantial back pressure to stay level. I feel it is a shift of the A C due to the airfoil but if so how do the faster Kolbs avoid this? Mark ________________________________ The information in this email and attachments hereto may contain legally pr ivileged, proprietary or confidential information that is intended for a pa rticular recipient. If you are not the intended recipient(s), or the employ ee or agent responsible for delivery of this message to the intended recipi ent(s), you are hereby notified that any disclosure, copying, distribution, retention or use of the contents of this e-mail information is prohibited and may be unlawful. When addressed to Takata customers or vendors, any inf ormation contained in this e-mail is subject to the terms and conditions in the governing contract, if applicable. If you have received this communica tion in error, please immediately notify us by return e-mail, permanently d elete any electronic copies of this communication and destroy any paper cop ies. Think Green - Please consider the environment before printing this email. ________________________________ Message 6 _____________________________________ Time: 02:08:29 PM PST US From: robert bean Subject: Re: Kolb-List: Nose down at higher speeds. Glad we got led astray from the circle turning version of seafoam. Also good to see another observation of the sensation felt when going over 75, in my case a MkIII. It is uncomfortable. It may have something to do with CG. Lots of owners with higher HP planes seem to be doing just fine at higher speeds. I feel that subtle differences like full enclosure canopy and fabric covered rears may be playing a part. In my case I have the open area behind the seats (gas tank area) and, more importantly, a really wide windshield that is shoving my nose down at higher speeds. I have drilled another set of front spar holes (set no. three) and may get around to trying them this year. BB MkIII, Suzuki strip is freshly mowed, tractors moved out of the shed, just have to retrieve the bird. On 30, Apr 2010, at 2:16 PM, Gray, Mark wrote: > Both myself and a buddy who fly a Firestar and a Twinstar have the same issue, when we get to around 75 mph indicated the planes start to nose over and begin to get a strange shuffling feel as if the wings are alternately shuffling forward, kind of a tail wag maneuver. This continues to become more pronounced if we allow the speed to increase and it becomes necessary to apply substantial back pressure to stay level. I feel it is a shift of the AC due to the airfoil but if so how do the faster Kolbs avoid this? > > Mark > > The information in this email and attachments hereto may contain legally privileged, proprietary or confidential information that is intended for a particular recipient. If you are not the intended recipient(s), or the employee or agent responsible for delivery of this message to the intended recipient(s), you are hereby notified that any disclosure, copying, distribution, retention or use of the contents of this e-mail information is prohibited and may be unlawful. When addressed to Takata customers or vendors, any information contained in this e-mail is subject to the terms and conditions in the governing contract, if applicable. If you have received this communication in error, please immediately notify us by return e-mail, permanently delete any electronic copies of this communication and destroy any paper copies. > > Think Green - Please consider the environment before printing this email. > > > > ________________________________ Message 7 _____________________________________ Time: 04:53:17 PM PST US From: "The Kuffels" Subject: Re: Kolb-List: Angle of Bank vs Stall Speed Hi Boyd, << Tom you said "Now when doing the same thing at 60 degree bank things get real exciting very soon, even at only 1/4 circle," ok would you like to explain in further detail just how ex citing and in what way? >> Sure. In any 1 g turn the amount of lift used to make the turn is then not available to resist the force of earth's gravity. This means you will increase your rate of descent. In shallow bank turns the effect is small and not very apparent even after a full circle. At 60 degrees however the rate of descent increases to a dramatic amount by at least a half circle, sometimes sooner depending on aircraft aerodynamics and your personal definition of exciting. But this is not the situation which kills pilots. Here we are talking about the descending quarter circle turn to final. Half way through the turn the pilot sees he is overshooting the runway path. What he should do is concentrate on maintaining the same airspeed, briefly increase his angle of bank, even up to 60 degrees if needed, and smoothly roll out. Doing this maintains a 1 g turn, ok a 1.1 g turn on rollout if one wants to quibble, which does not increase your stall speed for all practical purposes. You are at the increased bank angle for at most 1/8 of a circle. But because "increased bank angle means increased stall speed" is buried in the back, dark recesses of our training too many pilots try to save the situation by fudging the turn, either with rudder (uncoordinated flight) or by pulling back (increased load factor). My solution to this problem is the following basis for landing approaches. Opposite the approach end of the runway reduce power and set configuration (flaps and trim) to your desired approach speed. Maintain this speed *constantly* until at least you are established on final. Turns should normally be 20 - 30 degrees of bank. On turn to final the bank can be increased as described above for the time needed to complete the turn. This is guaranteed to not produce a stall or breathtaking rates of descent. Within this framework there are lots of variables such as adjusting power or adjusting airspeed along the back side of the power curve after being established on final. But from the start of the approach descent until at least established on final the sure and certain way to avoid an unintended stall is constant airspeed control. Again, go out to altitude and try some example quarter circle turns for yourself. Even at speeds unreasonably close to Vso you won't get even a nibble of a stall at angles of bank below aerobatic flight. Or come visit us in Whitefish and I'll demonstrate in an airplane easier to stall than a Kolb. Best, Tom ________________________________ Message 8 _____________________________________ Time: 07:27:12 PM PST US Subject: Kolb-List: Re: Nose down at higher speeds. From: "Eugene Zimmerman" Mark, To prevent, or stop the tail wag/wing shuffle keep both feet on the rudder pedals. Full wind screed "shape" affects nose down moment at increased speed. Narrower and round is better than wide and flat. The goal is to have the wind deflect around to the sides of the wind screen and fuselage rather than up over the top of the wing. I've tried both shapes, and while wider and flatter is more roomy, narrow and round is more efficient and makes the plane pitch neutral which is a much safer flight characteristics at higher speed. attached is a photo with the narrow rounded wind screen which increased my top speed about 10 mph. My other wind screen was the full width of the wing gap cover and approximately flat along the leading edge of the gap cover. Gene Read this topic online here: http://forums.matronics.com/viewtopic.php?p=296347#296347 Attachments: http://forums.matronics.com//files/landing_195.jpg ________________________________ Message 9 _____________________________________ Time: 09:07:19 PM PST US From: "Greg" Subject: Re: Kolb-List: Nose down at higher speeds. Mark, Are you sure your are not experiencing aileron flutter? Greg ----- Original Message ----- From: Gray, Mark To: kolb-list@matronics.com Sent: Friday, April 30, 2010 3:16 PM Subject: Kolb-List: Nose down at higher speeds. Both myself and a buddy who fly a Firestar and a Twinstar have the same issue, when we get to around 75 mph indicated the planes start to nose over and begin to get a strange shuffling feel as if the wings are alternately shuffling forward, kind of a tail wag maneuver. This continues to become more pronounced if we allow the speed to increase and it becomes necessary to apply substantial back pressure to stay level. I feel it is a shift of the AC due to the airfoil but if so how do the faster Kolbs avoid this? Mark ------------------------------------------------------------------------- ----- The information in this email and attachments hereto may contain legally privileged, proprietary or confidential information that is intended for a particular recipient. 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