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stalls & spins

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graham(at)gflight.f9.co.u
Guest

Posted: Tue Aug 01, 2006 3:02 pm Post subject: stalls & spins

Hi All

I was greatly saddend to hear about Cliff Shaw's accident. His happened 

near the ground on approach; as most of you know I have some experience 

of Europa stall/spin, mine happened just after take off. In both cases 

spin recovery is impossible this close to the ground, indeed partial 

recovery may make things worse. You hit the ground harder.



 Pete Clarke tested the spins of the original Classic prototype, G-YURO 

extensively. One notable feature he found was that even after a twelve 

turn spin he could let go of the controls  and the aeroplane would 

recover in less than two turns.



There are many GA types that are designed to be almost spin proof, this 

is a mixed blessing because if it's hard to spin it will be just as hard 

to stop the spin when it occurs. The Yankee was notorious and there were 

several fatal accidents until intentional spinning during training was 

forbidden. Remember also that very few certified or homebuilt GA types 

had anything like the testing the Europa had. I remember Richard Trikle 

asking Pete Clarke if he'd test the Kiss. No American pilot was prepared 

to do it.



There are quite a few Classics that have a nasty wing drop flaps down. 

G-KWIP was one. We had removed the stall strips because we felt we 

needed the extra take off performance for farm strip flying. Ours was 

around 450 meters at the time. The trouble with the Classic wing is that 

it is not easy to finish the leading edge without degrading the very 

subtle leading edge shape, which has a slight bump underneath and a 

fairly sharp nose radius. Eventually, after much arm twisting, I got 

hold of  the coordinates of the airfoil and made some templates for the 

leading edge. These were used on several Classics, Charlie Laverty's, 

Tony Higgins' and Colin Smallwood's, I haven't heard from Tony re flying 

qualities but the other two have excellent stall characteristics and so 

does Trevor Jackson's, (kit no. 4!)

This illustrates the variability that Mike Parkin mentions.



Ivan did a lot of tuft testing trying to master the stalling 

characterisitics and found that as long as the stall starts at the 

leading edge it will be relatively progressive. However, sometimes the 

stall starts at the trailing edge and then the whole upper surface 

"unzips" and will cause a sharp wing drop. The stall strips help to make 

the stall start at the front and at the wing root. The sharp LE radius 

has a similar effect and I'm sure this is why some Classics are 

unpredictable ( too large LE radius) whereas most XSs, which have a jig 

moulded LE are relatively benign. (Not that I've flown many btw, so get 

a second opinion!) The XS also has more washout which helps keep the 

stall away from the tips.



Mike will have a much more valid opinion than me but I believe the 

sensible way to monitor airspeed is by angle of attack, the instrument 

tells that that your airspeed is going to change, you can correct the 

changed AoA instantly and speed won't change The ASI tells you at least 

20 seconds after it's changed which means you then have to regain 

momentum which will take another 20 seconds or more. Another advantage 

that correct AoA is not dependant on weight, so the figure for stall, 

cruise max range etc all remain constant.

my 2 cents

Graham



 	  Quote: 	
		  From: "Mike Parkin" <mikenjulie.parkin(at)btopenworld.com>

Subject: Re Wing Drop in the Stall

  



 Jos,



I think that the original foam built wings are likely to vary slightly 

more 

in performance than the factory made wings purely  because of the nature 

of 

construction.  Profiling the wing is a laborious process and the end 

result 

is very much an 'eyeball dependent' operation.  I think it would be fair 

to 

say that the jig made factory wings are likely to produce a more 

consistent 

result.

  The very nature of the 

wing 

seems to provide a useable amount of lift until the stall, at which 

point 

the loss of lift from the wing seems to be almost total.  Now if one 

wing 

stalls before the other it is conceivable that the aircraft might roll 

on 

its back.

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Wed Aug 02, 2006 1:13 am Post subject: Re: stalls & spins

Folks,



 	  graham(at)gflight.f9.co.u wrote: 	
		  

Mike will have a much more valid opinion than me but I believe the 

sensible way to monitor airspeed is by angle of attack, the instrument 

tells that that your airspeed is going to change, you can correct the 

changed AoA instantly and speed won't change The ASI tells you at least 

20 seconds after it's changed which means you then have to regain 

momentum which will take another 20 seconds or more. Another advantage 

that correct AoA is not dependant on weight, so the figure for stall, 

cruise max range etc all remain constant.

my 2 cents

Graham

	




There is much good information in Graham's message but I feel that this last paragraph is misleading. Unless your ASI is particularly sluggish, it will indicate changes in airspeed almost instantly (i.e. not 20 seconds later). What takes the time is actually changing the speed of the aircraft relative to  the surrounding air. Fitting an AoA gauge does not make your aircraft accelerate any quicker! 



Let's imagine the situation where you are on approach and your airspeed is a little below the optimum speed (the AoA is higher than desired). Assuming you are not too low, you lower the nose to increase the speed (and reduce the AoA). As soon as the nose is lowered, the AoA will decrease and if you have an AoA gauge that will be indicated immediately. The airspeed, however, does not change straightaway (the ASI lag!!!) After a while, your airspeed will settle at the new increased value. (perhaps a kind aerodynamics person can provide us with a succinct description of what causes the airspeed to increase when the AoA is reduced). 



Moving the stick forward to reduce the AoA is the crucial action. Having moved the stick, the pilot then has to wait until the speed stabilises before sampling the ASI again (all gliding instructors will remember giving this demo). If the speed doesn't have to change by very much (say, < 5 kts) then the pilot doesn't have to wait very long (certainly less than 20S).



The rational behind the talking ASI is that if the airspeed on approach is not far from the desired speed, then the pitch/throttle adjustments required to return to that speed are small and the time lag between making an adjustment and achieving the desired speed is small. The pilot is "nagged" into maintaining the correct airspeed through small changes in pitch/power.



By nagging the pilot to maintain a sensible speed, the talking ASI not only protects against stalling, it helps you obtain the stabilised approach that Mike Parkin enthused about and is so important when operating out of small fields.



I understand the benefits of flying by AoA and if someone produced a low cost, reliable, easy to fit and calibrate, AoA instrument that didn't require you to have your eyes in the cockpit on approach, I would be tempted to have one.



Mark

asarangan(at)YAHOO.COM
Guest

Posted: Wed Aug 02, 2006 6:15 am Post subject: stalls & spins

I don't see the ASI and the AOA as entirely different things, especialy

in a small GA cockpit. The ASI can be calibrated to read angles instead

of speed based on aircraft weight, like the movable outer ring that is

used for calibrating TAS based on temperature. A true AOA independent

of weight is useful only in large transport aircraft where the weight

could vary significantly.

--- Mark Burton <markb(at)ordern.com> wrote:

 	  Quote: 	

 Folks,

 graham(at)gflight.f9.co.u wrote:

 > 

 > Mike will have a much more valid opinion than me but I believe the 

 > sensible way to monitor airspeed is by angle of attack, the

 instrument 

 > tells that that your airspeed is going to change, you can correct

 the 

 > changed AoA instantly and speed won't change The ASI tells you at

 least 

 > 20 seconds after it's changed which means you then have to regain 

 > momentum which will take another 20 seconds or more. Another

 advantage 

 > that correct AoA is not dependant on weight, so the figure for

 stall, 

 > cruise max range etc all remain constant.

 > my 2 cents

 > Graham

 > 

 There is much good information in Graham's message but I feel that

 this last paragraph is misleading. Unless your ASI is particularly

 sluggish, it will indicate changes in airspeed almost instantly (i.e.

 not 20 seconds later). What takes the time is actually changing the

 speed of the aircraft relative to  the surrounding air. Fitting an

 AoA gauge does not make your aircraft accelerate any quicker! 

 Let's imagine the situation where you are on approach and your

 airspeed is a little below the optimum speed (the AoA is higher than

 desired). Assuming you are not too low, you lower the nose to

 increase the speed (and reduce the AoA). As soon as the nose is

 lowered, the AoA will decrease and if you have an AoA gauge that will

 be indicated immediately. The airspeed, however, does not change

 straightaway (the ASI lag!!!) After a while, your airspeed will

 settle at the new increased value. (perhaps a kind aerodynamics

 person can provide us with a succinct description of what causes the

 airspeed to increase when the AoA is reduced). 

 Moving the stick forward to reduce the AoA is the crucial action.

 Having moved the stick, the pilot then has to wait until the speed

 stabilises before sampling the ASI again (all gliding instructors

 will remember giving this demo). If the speed doesn't have to change

 by very much (say, < 5 kts) then the pilot doesn't have to wait very

 long (certainly less than 20S).

 The rational behind the talking ASI is that if the airspeed on

 approach is not far from the desired speed, then the pitch/throttle

 adjustments required to return to that speed are small and the time

 lag between making an adjustment and achieving the desired speed is

 small. The pilot is "nagged" into maintaining the correct airspeed

 through small changes in pitch/power.

 By nagging the pilot to maintain a sensible speed, the talking ASI

 not only protects against stalling, it helps you obtain the

 stabilised approach that Mike Parkin enthused about and is so

 important when operating out of small fields.

 I understand the benefits of flying by AoA and if someone produced a

 low cost, reliable, easy to fit and calibrate, AoA instrument that

 didn't require you to have your eyes in the cockpit on approach, I

 would be tempted to have one.

 Mark

 Read this topic online here:

 http://forums.matronics.com/viewtopic.php?p=51717#51717

Dave Miller

Joined: 10 Jan 2006
Posts: 51

Posted: Wed Aug 02, 2006 7:27 am Post subject: Stalls & spins

One useful thing about learning to fly in giders, was the constant yelling from the back seat; 

Keep the speed up 

Keep the string straight. 

 

I still miss the yaw string, the cheapest and most useful instrument made. 

 

I'm indebted to Carl for his comments on the ball. In what feels like straight and level flight, mine sits a bit to the left. 

My feeling was that the instrument was wrong, or that the view from the left seat was distorting my perspective, or that I'd just lost the touch for what is straight and level. 

 

Also to Mike for comments regarding the ailerons, mine are level on the ground, but seem to adopt a slight droop in cruise. 

 

Some things to look at and fix on C-FBZI 

 

Dave A061

BEBERRY(at)aol.com
Guest

Posted: Wed Aug 02, 2006 7:58 am Post subject: stalls & spins

The usual cause of stall on the approach - or anywhere I suppose, is the0 application of up elevator when pilot perception is that of being too low.

  

 The correct action should surely be emphasised again and again - elevator0 for change of speed and throttle for height.

  

 Patrick

willie.harrison(at)tinyon
Guest

Posted: Wed Aug 02, 2006 8:33 am Post subject: stalls & spins

Surely it depends on how much G you are pulling (or not)??



Willie Harrison

G-BZNY



 	  Quote: 	
		  -- Original Message --

To: europa-list(at)matronics.com

From: Andrew Sarangan <asarangan(at)yahoo.com>

Date: Wed, 2 Aug 2006 07:13:54 -0700 (PDT)

Subject: Re: Re: stalls & spins

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


I don't see the ASI and the AOA as entirely different things, especialy

in a small GA cockpit. The ASI can be calibrated to read angles instead

of speed based on aircraft weight, like the movable outer ring that is

used for calibrating TAS based on temperature. A true AOA independent

of weight is useful only in large transport aircraft where the weight

could vary significantly.

--- Mark Burton <markb(at)ordern.com> wrote:



> 

>

> Folks,

> graham(at)gflight.f9.co.u wrote:

> >

> > Mike will have a much more valid opinion than me but I believe the

> > sensible way to monitor airspeed is by angle of attack, the

> instrument

> > tells that that your airspeed is going to change, you can correct

> the

> > changed AoA instantly and speed won't change The ASI tells you at

> least

> > 20 seconds after it's changed which means you then have to regain

> > momentum which will take another 20 seconds or more. Another

> advantage

> > that correct AoA is not dependant on weight, so the figure for

> stall,

> > cruise max range etc all remain constant.

> > my 2 cents

> > Graham

> >

> There is much good information in Graham's message but I feel that

> this last paragraph is misleading. Unless your ASI is particularly

> sluggish, it will indicate changes in airspeed almost instantly (i.e.

> not 20 seconds later). What takes the time is actually changing the

> speed of the aircraft relative to  the surrounding air. Fitting an

> AoA gauge does not make your aircraft accelerate any quicker!

>

> Let's imagine the situation where you are on approach and your

> airspeed is a little below the optimum speed (the AoA is higher than

> desired). Assuming you are not too low, you lower the nose to

> increase the speed (and reduce the AoA). As soon as the nose is

> lowered, the AoA will decrease and if you have an AoA gauge that will

> be indicated immediately. The airspeed, however, does not change

> straightaway (the ASI lag!!!) After a while, your airspeed will

> settle at the new increased value. (perhaps a kind aerodynamics

> person can provide us with a succinct description of what causes the

> airspeed to increase when the AoA is reduced).

>

> Moving the stick forward to reduce the AoA is the crucial action.

> Having moved the stick, the pilot then has to wait until the speed

> stabilises before sampling the ASI again (all gliding instructors

> will remember giving this demo). If the speed doesn't have to change

> by very much (say, < 5 kts) then the pilot doesn't have to wait very

> long (certainly less than 20S).

>

> The rational behind the talking ASI is that if the airspeed on

> approach is not far from the desired speed, then the pitch/throttle

> adjustments required to return to that speed are small and the time

> lag between making an adjustment and achieving the desired speed is

> small. The pilot is "nagged" into maintaining the correct airspeed

> through small changes in pitch/power.

>

> By nagging the pilot to maintain a sensible speed, the talking ASI

> not only protects against stalling, it helps you obtain the

> stabilised approach that Mike Parkin enthused about and is so

> important when operating out of small fields.

>

> I understand the benefits of flying by AoA and if someone produced a

> low cost, reliable, easy to fit and calibrate, AoA instrument that

> didn't require you to have your eyes in the cockpit on approach, I

> would be tempted to have one.

>

> Mark

>

>

> Read this topic online here:

>

> http://forums.matronics.com/viewtopic.php?p=51717#51717

>








	


___________________________________________________________



Tiscali Broadband from 14.99 with free setup!

http://www.tiscali.co.uk/products/broadband/

paddyclarke(at)lineone.ne
Guest

Posted: Wed Aug 02, 2006 10:01 am Post subject: stalls & spins

Hi All,

I have to that I'm with Graham here. Not only does the AoA system  

solve the problem of the  increased  stall speed with bank, it also  

indicates instantly if an accelerated pitch input is made - not so  

the ASI.

I have the Proprietary Systems AoA. I was recently asked to  

demonstrate it to another Europa builder. Having investigated the low  

speed handling solo, and with approx half fuel, the day before, I was  

surprised by how much faster the IAS was for the same AoAs, with 2 up  

and near full fuel.

The system is relatively easy to fit if it is put in as original  

equipment and, to answer Marks point, has a good aural warning. Just  

remember to ignore the American lady when she says 'Angle, Angle,  

PUSH !' and you're in the flare !!

Cheers, Paddy

 	  Quote: 	
		   Do Not Archive




	


Paddy Clarke



Europa XS - 404 G-KIMM

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Wed Aug 02, 2006 11:18 am Post subject: Re: stalls & spins

 	  paddyclarke(at)lineone.ne wrote: 	
		  Hi All,

and, to answer Marks point, has a good aural warning. Just  

remember to ignore the American lady when she says 'Angle, Angle,  

PUSH !' and you're in the flare !!

	




Yes, but it still requires you to look inside the cockpit while flying the approach to see the AoA display. Once you get to the point of flaring you don't need any instruments at all.

carl(at)flyers.freeserve.
Guest

Posted: Wed Aug 02, 2006 2:29 pm Post subject: stalls & spins

I would suggest that the ASI should only be part of the equation. You need 

to know the correct attitude (with reference to the horizon) that gives a 

safe approach speed. If you fly with reference to the ASI alone you end up 

chasing the airspeed and worse still have your eyeball inside the cockpit 

instead of keeping an eye on the attitude and where you are heading.



On my first ever solo (in a glider) the ASI failed completely and I had to 

fly the circuit and land without any speed reference whatsoever. Fortunately 

I was taught to fly by attitude and coped with what would have otherwise 

been a nasty situation.



If your airspeed indicator were to fail would you know what attitude to fly 

to land safely. If you dont recognise what attitude gives a safe flying 

speed (flaps up and flaps down) would you be able to cope with such an 

emergency.



---

Trevpond(at)aol.com
Guest

Posted: Wed Aug 02, 2006 2:33 pm Post subject: stalls & spins

The correct action Patrick is to fly the aircraft to the published0 numbers!

  

  

  

 Trev Pond

 Kit 598

asarangan(at)YAHOO.COM
Guest

Posted: Wed Aug 02, 2006 7:45 pm Post subject: stalls & spins

I agree entirely. In fact I teach my primary students how to approach

and land with all instruments covered, including airspeed and

altimeter. If you know the pitch + power combination for every flight

configuration, you don't need much else. However, the pitch+power

combination depends on aircraft weight and load factor. If you use

AOA+power, it would be independent of weight and load factor. This is

why some people prefer AOA. My point was that rarely do we have large

variations in load factor or weight to make this a highly useful

instrument. I would be interested to know if there are any studies that

show than an AOA makes that much difference in stall-spin accidents. In

my observation flying with many pilots, new and old, by the time

someone gets into a dangerously slow airspeed and a screwed up

approach, they are rarely able to pay attention to the flight

instruments or even hear the stall horn. What saves them is their basic

airmanship to recognize the unusual attitude and recover it to a

familiar pitch + power configuration. I doubt that yet another

instrument on the panel is going to be of much help to those who get

that far into the danger zone.





--- Carl Pattinson <carl(at)flyers.freeserve.co.uk> wrote:



 	  Quote: 	
		   

 <carl(at)flyers.freeserve.co.uk>

 

 I would suggest that the ASI should only be part of the equation. You

 need 

 to know the correct attitude (with reference to the horizon) that

 gives a 

 safe approach speed. If you fly with reference to the ASI alone you

 end up 

 chasing the airspeed and worse still have your eyeball inside the

 cockpit 

 instead of keeping an eye on the attitude and where you are heading.

 

 On my first ever solo (in a glider) the ASI failed completely and I

 had to 

 fly the circuit and land without any speed reference whatsoever.

 Fortunately 

 I was taught to fly by attitude and coped with what would have

 otherwise 

 been a nasty situation.

 

 If your airspeed indicator were to fail would you know what attitude

 to fly 

 to land safely. If you dont recognise what attitude gives a safe

 flying 

 speed (flaps up and flaps down) would you be able to cope with such

 an 

 emergency.

 

 


	




Andrew Sarangan

http://www.sarangan.org

paddyclarke(at)lineone.ne
Guest

Posted: Thu Aug 03, 2006 1:37 am Post subject: stalls & spins

Hi Mark,

I'm sure we can agree that no instruments are needed in the flare -  

my attempt at a bit of levity obviously didn't come through!

I am a great fan of your talking ASI, it's a valuable contribution to  

flight safety and I would certainly have fitted one if I didn't have  

an AoA indicator. It is also much easier to retrofit, though it does  

depend on the validity of the target airspeed. To look at the  

indications of an AoA you have, of course, to glance inside - though  

mine is fitted at the very top of the instrument panel, so I might  

just pick up the bright lights in my peripheral vision.

However, one day you may be making a rather tight turn onto final,  

roll on a bit of extra bank to stop the tailwind blowing you through  

the C/L, then pull rather sharply back as you realise you've let the  

nose drop - just as you hit the turbulence from the top of the big  

hangar. An American lady giving you a harsh rebuke may just save your  

life, whereas the English lady would be quietly content. After all,  

your airspeed is exactly the number she's been told to expect.

All the Best, Paddy

 	  Quote: 	
		   Mark Burton wrote:

 Yes, but it still requires you to look inside the cockpit while  

 flying the approach to see the AoA display. Once you get to the  

 point of flaring you don't need any instruments at all.



Do Not Archive
	


Paddy Clarke



Europa XS - 404 G-KIMM

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Thu Aug 03, 2006 2:10 am Post subject: Re: stalls & spins

 	  paddyclarke(at)lineone.ne wrote: 	
		  Hi Mark,

I'm sure we can agree that no instruments are needed in the flare -  

my attempt at a bit of levity obviously didn't come through!

I am a great fan of your talking ASI, it's a valuable contribution to  

flight safety and I would certainly have fitted one if I didn't have  

an AoA indicator. It is also much easier to retrofit, though it does  

depend on the validity of the target airspeed. To look at the  

indications of an AoA you have, of course, to glance inside - though  

mine is fitted at the very top of the instrument panel, so I might  

just pick up the bright lights in my peripheral vision.

However, one day you may be making a rather tight turn onto final,  

roll on a bit of extra bank to stop the tailwind blowing you through  

the C/L, then pull rather sharply back as you realise you've let the  

nose drop - just as you hit the turbulence from the top of the big  

hangar. An American lady giving you a harsh rebuke may just save your  

life, whereas the English lady would be quietly content. After all,  

your airspeed is exactly the number she's been told to expect.

All the Best, Paddy

	




Hi Paddy,



I agree with everything you say here except the bit about the turbulence because if the wind speed (relative to the aircraft) changes rapidly, the talking ASI will pick that up as quickly as the AoA instrument does. As you point out, the real benefit that AoA gives over airspeed is the detection of the 

accelerated stall. It did occur to me during development of the talking ASI that by adding an accelerometer the widget could take into account the higher loading. Perhaps I should investigate that idea further.



I've said enough now, everyone must be bored to tears.



If anyone wants to discuss the talking ASI further, please send email to enquires(at)smartavionics.com



Regards,



Mark

Mark Burton

Joined: 10 Jan 2006
Posts: 74

Posted: Sat Mar 17, 2007 2:25 pm Post subject: Re: stalls & spins

Folks,



Thinking back to the conversation last year on stall+spins and the recent article in GASCO Flight Safety about cheese (you have to read the article to understand).



Some of you may be interested to know that I am now producing Mk2 SmartASS units that not only provide the features of the MK1 units (talking ASI, and audible speed director) but it also features an accelerometer that measures the G you are pulling and factors that into the speed director calculation. It works very well as an aid to preserving the "stall speed margin" as well as making flying a stabilised approach ridiculously easy.



I must stress that the SmartASS is not a stall warning device.



The Mk2 units also feature audible undercarriage and general alerts.



As ever, technical blurb, prices, etc. can be found at www.smartavionics.com



Cheers,



Mark

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