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Stall Question

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dhkey(at)msn.com
Guest

Posted: Mon Sep 04, 2006 7:15 pm Post subject: Stall Question

Say I had a stall warning device on my wing that went off at 40 mph. Then 

lets say I turned downwind to base at a 75% degree turn at 55mph. I would 

stall because of the increased G loads but would the stall warning device go 

off?

jindoguy(at)gmail.com
Guest

Posted: Mon Sep 04, 2006 7:40 pm Post subject: Stall Question

David, Seems like a "how long is a piece of string" question. The simple answer is no, if it's set for 40 it won't go off at 55. If it's an impact device like an airspeed indicator in reverse, 55 knots worth of air molecules would keep the device from triggering. With a little clever engineering you could add a sliding door or similar way to close down the opening so that at 55 and 2G's you get only 40 knots worth of air molecules and the device triggers. 

Fun thought experiment, thanks.



Rick



On 9/4/06, David Key <dhkey(at)msn.com (dhkey(at)msn.com)> wrote: 	  Quote: 	
		   --> Kolb-List message posted by: "David Key" <dhkey(at)msn.com (dhkey(at)msn.com)>



Say I had a stall warning device on my wing that went off at 40 mph. Then

lets say I turned downwind to base at a 75% degree turn at 55mph. I would 



	


-- 

Rick Girard

"Ya'll drop on in"

takes on a whole new meaning

when you live at the airport.  [quote][b]

Eugene Zimmerman

Joined: 10 Jan 2006
Posts: 392

Posted: Tue Sep 05, 2006 4:32 am Post subject: Stall Question

David,



The simple answer is yes.  If your stall warning is a true angle of  

attack indicator and not a mere airspeed warning.



On Sep 4, 2006, at 11:13 PM, David Key wrote:



 	  Quote: 	
		   



 Say I had a stall warning device on my wing that went off at 40  

 mph. Then lets say I turned downwind to base at a 75% degree turn  

 at 55mph. I would stall because of the increased G loads but would  

 the stall warning device go off?

Steve Boetto

Joined: 11 Jan 2006
Posts: 364

Posted: Tue Sep 05, 2006 5:21 am Post subject: Stall Question

David,

 Stalls are a function of Angle of Attack not airspeed. If it truly is an AA  indicator it will measure the angle of attack vs airspeed. On a Cub it is as  simple as the bottom half of the door if it is open.

  

 Or so I was taught by my Old  Mentor.

  

 Steve

  [quote][b]

dhkey(at)msn.com
Guest

Posted: Tue Sep 05, 2006 8:16 am Post subject: Stall Question

So are you saying that it will stall or not? I'm talking about the little 

metal thing that yes measures the AOA

 	  Quote: 	
		  From: N27SB(at)aol.com

Reply-To: kolb-list(at)matronics.com

To: kolb-list(at)matronics.com

Subject: Re: Stall Question

Date: Tue, 5 Sep 2006 09:20:45 EDT

David,

Stalls are a function of Angle of Attack not airspeed. If it truly is an AA

indicator it will measure the angle of attack vs airspeed. On a Cub it is 

as

simple as the bottom half of the door if it is open.

Or so I was taught by my Old  Mentor.

Steve

Russ Kinne

Joined: 27 Jan 2006
Posts: 182

Posted: Tue Sep 05, 2006 10:15 am Post subject: Stall Question

DavidThe little metal thingie measures the wind coming across the leading edge -- if the wing is near a stall the apparent wind will push it up, and it will beep. Or blink.    AT ANY AIRSPEED    -- and the wing will stall if you go any slower.  It does measure AOA and that's what you need to monitor. Cub doors work great!

Russ

do not archive



On Sep 5, 2006, at 12:16 PM, David Key wrote:

[quote]--> Kolb-List message posted by: "David Key" <dhkey(at)msn.com (dhkey(at)msn.com)>

So are you saying that it will stall or not? I'm talking about the little metal thing that yes measures the AOA





  	  Quote: 	
		  From: N27SB(at)aol.com (N27SB(at)aol.com)

Reply-To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)

To: kolb-list(at)matronics.com (kolb-list(at)matronics.com)

Subject: Re: Stall Question

Date: Tue, 5 Sep 2006 09:20:45 EDT

David,

Stalls are a function of Angle of Attack not airspeed. If it truly is an AA

indicator it will measure the angle of attack vs airspeed. On a Cub it is as

simple as the bottom half of the door if it is open.

Or so I was taught by my Old  Mentor.

Steve

 	




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Ed in JXN

Joined: 24 Mar 2006
Posts: 122

Posted: Tue Sep 05, 2006 12:32 pm Post subject: Stall Question

Hi All,

  

         I can't  emphasize enough how the 'tab-type' stall warning indicator is NOT an  angle-of-attack (AOA) device.  It works on slower GA-type aircraft in a  narrow airspeed range.  The fact it works in a turn is more indicative of  its error range than its accuracy.

  

         True AOA uses  a computer and factors in weight, air density, wing configuration (flap  position), and possibly other factors.  It works great, even in bumpy  air.

  

         If the tab  thingy worked, wouldn't some type of yarn also work at the right location?   If it worked as previously stated, we'd see it on Falcons, Gulfstreams, etc. one  would think.

  

         Sorry, not  trying to flame but want to see more accurate info posted.

  

 Ed in JXN

 MkII/503

  

  

 [quote]   ---

Russ Kinne

Joined: 27 Jan 2006
Posts: 182

Posted: Tue Sep 05, 2006 4:11 pm Post subject: Stall Question

I stand corrected  -- sort of. The little metal tab-thingie WORKS AS  an AOA indicator, at the speeds Kolbs fly; and can be trusted to warn you of an impending stall. I don't think we need a super-accurate, computer-controlled AOA indicator, though of course it's more accurate -- Yarn probably would work IF you kept your eye on it and nothing else. I doubt it would last long on Falcons & Gulfstreams.  

A light and/or horn is much more practical -- IMHORuss Kinne

do not archive



On Sep 5, 2006, at 4:32 PM, Ed Chmielewski wrote:

[quote]  Hi All,

  

         I can't emphasize enough how the 'tab-type' stall warning indicator is NOT an angle-of-attack (AOA) device.  It works on slower GA-type aircraft in a narrow airspeed range.  The fact it works in a turn is more indicative of its error range than its accuracy.

  

         True AOA uses a computer and factors in weight, air density, wing configuration (flap position), and possibly other factors.  It works great, even in bumpy air.

  

         If the tab thingy worked, wouldn't some type of yarn also work at the right location?  If it worked as previously stated, we'd see it on Falcons, Gulfstreams, etc. one would think.

  

         Sorry, not trying to flame but want to see more accurate info posted.

  

 Ed in JXN

 MkII/503

  

  

 [quote]  ---

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Tue Sep 05, 2006 4:37 pm Post subject: Stall Question

|I stand corrected  -- sort of. The little metal tab-thingie WORKS AS

| an AOA indicator, at the speeds Kolbs fly; and can be trusted to 

warn

| you of an impending stall. I don't think we need a super-accurate,

| computer-controlled AOA indicator, though of course it's more

| accurate --

 | Russ Kinne



Russ:



What are you basing your Kolb experience on?



Don't need another gadget on my Kolb.



Found out, early on, Kolbs stall if you get below the stall speed.



Also found out, at the same time, the ground is extremely hard and 

unforgiving.



Through experience, demonstrating the MKIII, back in the good old 

days, it was extremely difficult, and most of the time, impossible to 

get the MKIII into an accelerated stall, intentionally.  Once in a 

while, with a rather large passenger, I could get it to fall through 

an extremely tight turn.  However, as soon as it was detected, it 

could as quickly be gotten out of it.



Take care,



john h

mkIII (that needs airspeed to prevent stalls)

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Steve Boetto

Joined: 11 Jan 2006
Posts: 364

Posted: Wed Sep 06, 2006 6:00 am Post subject: Stall Question

In a message dated 9/5/2006 10:03:19 P.M. Eastern Standard Time,  jhauck(at)elmore.rr.com writes:

  	  Quote: 	
		  Through    experience, demonstrating the MKIII, back in the good old 

days, it was    extremely difficult, and most of the time, impossible to 

get the MKIII    into an accelerated stall, intentionally.   john  h. 	
 That makes sense John. When I first started flying the Fire on floats turns  felts odd and I had a tendency to "milk

 ' around a turn with a shallow bank and too much rudder. Bryan M. saw this  from the ground and recommended that I try this: Drop the nose a bit, rock in  about 45 deg of bank and Haul Back on the stick. The airplane turns on a dime  with no tendency to stall. It feels a lot like doing a hook turn on a slalom ski  around a float. Why does a Kolb do this and most other AC do not?

  

  

 steve b

  

 

  

  [quote][b]

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Wed Sep 06, 2006 6:22 am Post subject: Stall Question

|   Drop the nose a bit, rock in

| about 45 deg of bank and Haul Back on the stick. The airplane turns 

on a dime

| with no tendency to stall. It feels a lot like doing a hook turn on 

a slalom

| ski  around a float. Why does a Kolb do this and most other AC do 

not?

|

|

| steve b



Steve B:



I don't know about airplanes, but this is how we turn helicopters in a 

hard banking turn.  We turn the helicopter with aft cyclic and the 

Kolb with elevator.  I don't have enough experience flying other fixed 

wing aircraft to comment on how they fly.  A few hours in a 152 to get 

a private ticket 16 years ago is the extent of my "other" fixed wing 

type experience.  Got a few hours playing with Kolbs though.  



john h

mkIII

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

Steve Boetto

Joined: 11 Jan 2006
Posts: 364

Posted: Wed Sep 06, 2006 6:29 am Post subject: Stall Question

Thanks John.

 After thinking about it, I'm going to guess that it has to do with a short  fat low aspect wing mated with low mass. This is probably a situation where the  low mass works for you.

  

 BTW,  I have seen you do this maneuver at low airspeeds and low  altitudes. Its a cool turn.

  

 steve b.

  [quote][b]

Ed in JXN

Joined: 24 Mar 2006
Posts: 122

Posted: Wed Sep 06, 2006 6:56 am Post subject: Stall Question

Hi Russ,

  

         I  believe it would be more accurate (and safer) to refer to it as a stall warning  indicator or stall tab, which is all it is.  It really has no function as  an AOA, even though it sounds good.  It doesn't get any info (weight, air  density, etc.) to act as an AOA.

  

         Even in  turns, they're notoriously unreliable.  Go off in turbulence, don't go off  at certain times when they should.  They're on lots of the GA aircraft I  fly, singles and twins, and are the LAST thing I believe for aviating  info.

  

 Ed in JXN

  

  

 [quote]   ---

Dennis.Kirby(at)kirtland.
Guest

Posted: Wed Sep 06, 2006 7:23 am Post subject: Stall Question

"John Hauck" wrote:  << Through experience, demonstrating the MKIII, it was

extremely difficult to get the MKIII into an accelerated stall,

intentionally.  Once in a while, with a rather large passenger, I could get

it to fall through an extremely tight turn. >> 



I have discovered that my Mark-III has a very effective, built-in stall

warning device.  It is the "growl" you hear when, just prior to the stall,

the separated, turbulent airflow comes off the wing and goes through the

prop.  Impossible to ignore.



This pre-stall growl happens in straight-ahead stalls (especially with power

on), and in banked, accelerated stalls (especially with a passenger).

Accompanying this pre-stall growl is a slight bobbing of the nose.  Fly any

slower (or bank any steeper), and the plane will stall.  Gotta love an

airplane that "talks" to you so clearly!



Dennis Kirby

912ul, 58 hrs

New Mexico

APilot(at)webtv.net
Guest

Posted: Wed Sep 06, 2006 3:41 pm Post subject: Stall Question

My Mark III Classic has a noise or a growl, but I thought that it was

cavitation of the prop.  Maybe not.

Russ Kinne

Joined: 27 Jan 2006
Posts: 182

Posted: Thu Sep 07, 2006 8:05 am Post subject: Stall Question

EdThanx reply, but I tend to argue that the metal tab that's always been a called 'stall warning indicator', "has no function as an AOA indicator". 

The AOA is a measure of how the Apparent Wind hits the leading edge of the wing. At high AOA's the airflow will move up across the LE, pushing the tab up & sounding horn or lighting light. You of course know all this. But it does usually work.

Sure, it's lo-tech and doesn't take into account weight, wing configuration, air density, other factors, which affect the airspeed at which the AOA will change -- but IMHO it IS a crude way to know when the AOA changes enough to push up the little metal tab, and to warn the pilot of an impending stall. 

Yes, it's unreliable, gives false negatives and false positives, and I don't trust it any more than you do; but I doubt any Kolber is going to install a much more complicated and much more accurate system. I even wore out the horn once, C-170.

Another possibility would be a vane and indicator-arc but it would probably have to be mounted below and in front of the leading edge, would be fragile and I doubt worth the trouble. 

But knowing AOA somehow is vital to safe flying.

Russ in CT



On Sep 6, 2006, at 10:55 AM, Ed Chmielewski wrote:

[quote]  Hi Russ,

  

         I believe it would be more accurate (and safer) to refer to it as a stall warning indicator or stall tab, which is all it is.  It really has no function as an AOA, even though it sounds good.  It doesn't get any info (weight, air density, etc.) to act as an AOA.

  

         Even in turns, they're notoriously unreliable.  Go off in turbulence, don't go off at certain times when they should.  They're on lots of the GA aircraft I fly, singles and twins, and are the LAST thing I believe for aviating info.

  

 Ed in JXN

  

  

 [quote]  ---

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