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
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| Subject: | Re: Angle of Bank vs Stall Speed/Approach Technique |
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
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| Subject: | Re: Angle of Bank vs Stall Speed |
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 <kuffel@cyberport.net> 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
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| Subject: | Re: 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
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| Subject: | 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
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| Subject: | 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
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| Subject: | Re: 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
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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
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email.
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>
>
Message 7
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| Subject: | Re: 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
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| Subject: | Re: Nose down at higher speeds. |
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
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| Subject: | Re: 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. 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
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