Hi Guys, here is another "rookie pilot" question haha
How easy is it to enter a whipstall? Dont get me wrong..as i have no intention of ever trying.
I am asking this question because I want to make sure I never do!
During my training, we practiced many stalls both with engine recovery and without, and I still practice them often, especially ones with engine recovery. I must admit that I'm always nervous when doing this though and would appreciate your thoughts here.
My instructors taught me that at the point of stall, I should gently pull the bar and "ease" the nose down. Avoiding any sudden jerking sort of action was drilled into me, and through all the stalls I've done, I have never felt that I was not in control of the nose. But my question to you is as above. How easy is it to enter a W Stall? And more importantly, are there any immediate syptoms of the catastrophe that will no doubt follow? I have never heard of any successfull recoveryfrom one of these so I'm hoping you can give me some advice to help avoid this at all costs.
From what I understand, the danger exists when the rate at which the nose pitches up is too excessive. IE the trike ends up being at an angle that is too vertical. This allows the part of the plane aft of the CofG to "tailslide" a little before violently pitching forward. Or am I totally off??
The Danger of the Whipstall
-
KFA
- Toooooo Thousand
- Posts: 2789
- Joined: Mon Jun 19, 2006 8:09 pm
- Location: Now at Petit (FARA)
- Contact:
Re: The Danger of the Whipstall
Hope this works, will attach a word document. All credit to Jean d’Assonville for his description. Sorry file too big
WHIPSTALL – THE KILLER!
There is a distinct lack if true knowledge and understanding what a whipstall is and why it will kill you. This ignorance amongst both recreational pilots as well as Weightshift Microlight instructors is due to a lack of published information in the subject, as well as the non-existence of “whipstalls” in the ANR syllabus. With this article, I hope to enlighten all weightshift pilots with an understanding of the whipstall, it’s dangers and how to avoid them.
A “whipstall” is produced when you have a sudden loss of thrust in a radically steep climb-out. Due to the extreme stresses on your airframe, your undercarriage will probably part company with your wing and you will find yourself with the impossible task of landing without your wing. By which time you will die!
In a medium (safe) climb we have increased thrust and angle of attack and the centre of lift has moved ahead of the centre of gravity. A stall in this situation would be relatively mild and easy to recover from.
FIG I
STRAIGHT AND LEVEL SAFE CLIMB
Modern weightshift microlights are so efficient in a climb due to their outrageous power to weight ratios and super wing designs, that you will often fund yourself in an extremely steep climb-out. Exhilarating, isn’t it? This radically steep climb-out is one of the most dangerous things you can do with a trike. If in this radically steep climb you have a sudden loss of thrust, due to maybe and engine failure, broken prop shaft etc., and you do not exercise the correct recovery, you will most probably whipstall, your aircraft will breakup and you will die.
THIS IS WHY! FIG II
Note: In the steeper climb(B), which is more than 45° the resultant force of drag plus weight is increased considerably, which means that when the thrust is suddenly lost, flying speed will decrease more rapidly in the situation (B)
When thrust is suddenly lost in situation (B), the rapid loss of flying speed and radical increase of angle of attack causes the sudden loss of centre of lift, which was close to the leading edge.
FIG III
As the wing plummets, in its new stalled flight path created due to the resultant force of momentum and weight, a new and powerful lift centre develops on the trailing edge of the wing. This is where the destructive force is created!!
The two prime forces with which we are now concerned are the weight and this new powerful lift centre which is created near the trailing edge due to the new wide angle of attack. (In flex wings, the flexible battens which in normal flight allows reflex will now bend in the opposite direction, helping boost the lift in this area.)
OBSERVE
These two opposing forces create a couple which will cause the trapeze to be trust very powerfully against the chest of the pilot, which in turn causes the undercarriage to rotate backwards around the wing.
If the angle of climb was radical enough to produce a proper whipstall, the undercarriage will have enough momentum to swing backwards, upwards and right over the wing and as it goes over will gain enough momentum to go around again. It is during these loops that the airframe is highly stressed. The front aerofoil tube normally breaks in the first loop, destroying the triangular structure, and somewhere in the second loop the upright pylon breaks off, not having the triangular structure’s support. This means that you are now left to land the undercarriage without a wing, while your wing floats gently to Mother Earth, by which time you are dead!
AVOIDING PREMATURE DEATH
As you can see, the prime factors causing a whipstall are the sudden loss of thrust in a very steep climb of 45° or more.
Therefore, never climb out at more than 40° in your trike. (A sudden loss of thrust at this lower angle would only cause a mild and easily recoverable stall).
There are however times when you find yourself in a climb steeper than you anticipated.
These are:
After recovering from a steep turn in which you did cot control your sideslip, and your airspeed increased close to VNE and come out of the turn with a higher power setting.
AVOID THIS by controlling your sideslip, watching your airspeed, and recovering passively, from the side slipping turn with a low enough power setting not to go straight into a climb!
The other situation is when you pull the bar in, apply full power and do a “Shoot-up!” The aircraft, being ultra light and the wing being super efficient and the engine being very powerful, the aircraft will go into a radically steep climb. (These are fun and they are enjoyed by many pilots -/ but note that most of our fellow aviators who had a sudden loss of thrust in these radical climbs are no longer with us)
AVOID THIS by not doing these radical “shoot-ups”. If you can’t resist the temptation of a “shoot-up” then do not apply full power when you pull the wing in. Rather pull the wing in, and then with sufficient power to maintain straight and level flight gain airspeed, gently feed the bar forward to alter pitch, (not more than 40°), slowly apply power to maintain the climb while easing the bar back in, so as to climb out with a low angle of attack and good airspeed!
You might however one day find yourself in a steep attitude for some unforeseen reason, in which you fear you might do a whipstall, DO NOT, because of fright, cut power. Keep the power setting that got you there, push the bar sideways, which will initiate a “stall turn”, As the aircraft turns, and goes into a nose down attitude, reduce your power setting and recover straight and level flight.
TO RECAP
Whipstalls are caused by sudden loss of thrust in radical climbs.
1. DO NOT climb at and angle more than 40°.
2. DO NOT do radical “shoot-ups”
3. RECOVER passively and gently after side slipping turns
4. If you find yourself in a potential whipstall situation, keep the power setting, initiate a “stall turn”, then recover to straight and level flight.
Fellow aviators, whipstalls can and have killed people/ To avoid premature death, respect the immense destructive forces involved, never climb out with steeper than 40° and apply the above avoidance techniques.
I appeal to the weightshift instructors to make sure that their students understand clearly the hazards, the basic aerodynamics and avoidance techniques involved in whipstalls. It is not necessary to loose even one more fellow pilot to a whipstall
Jean d’Assonville
WHIPSTALL – THE KILLER!
There is a distinct lack if true knowledge and understanding what a whipstall is and why it will kill you. This ignorance amongst both recreational pilots as well as Weightshift Microlight instructors is due to a lack of published information in the subject, as well as the non-existence of “whipstalls” in the ANR syllabus. With this article, I hope to enlighten all weightshift pilots with an understanding of the whipstall, it’s dangers and how to avoid them.
A “whipstall” is produced when you have a sudden loss of thrust in a radically steep climb-out. Due to the extreme stresses on your airframe, your undercarriage will probably part company with your wing and you will find yourself with the impossible task of landing without your wing. By which time you will die!
In a medium (safe) climb we have increased thrust and angle of attack and the centre of lift has moved ahead of the centre of gravity. A stall in this situation would be relatively mild and easy to recover from.
FIG I
STRAIGHT AND LEVEL SAFE CLIMB
Modern weightshift microlights are so efficient in a climb due to their outrageous power to weight ratios and super wing designs, that you will often fund yourself in an extremely steep climb-out. Exhilarating, isn’t it? This radically steep climb-out is one of the most dangerous things you can do with a trike. If in this radically steep climb you have a sudden loss of thrust, due to maybe and engine failure, broken prop shaft etc., and you do not exercise the correct recovery, you will most probably whipstall, your aircraft will breakup and you will die.
THIS IS WHY! FIG II
Note: In the steeper climb(B), which is more than 45° the resultant force of drag plus weight is increased considerably, which means that when the thrust is suddenly lost, flying speed will decrease more rapidly in the situation (B)
When thrust is suddenly lost in situation (B), the rapid loss of flying speed and radical increase of angle of attack causes the sudden loss of centre of lift, which was close to the leading edge.
FIG III
As the wing plummets, in its new stalled flight path created due to the resultant force of momentum and weight, a new and powerful lift centre develops on the trailing edge of the wing. This is where the destructive force is created!!
The two prime forces with which we are now concerned are the weight and this new powerful lift centre which is created near the trailing edge due to the new wide angle of attack. (In flex wings, the flexible battens which in normal flight allows reflex will now bend in the opposite direction, helping boost the lift in this area.)
OBSERVE
These two opposing forces create a couple which will cause the trapeze to be trust very powerfully against the chest of the pilot, which in turn causes the undercarriage to rotate backwards around the wing.
If the angle of climb was radical enough to produce a proper whipstall, the undercarriage will have enough momentum to swing backwards, upwards and right over the wing and as it goes over will gain enough momentum to go around again. It is during these loops that the airframe is highly stressed. The front aerofoil tube normally breaks in the first loop, destroying the triangular structure, and somewhere in the second loop the upright pylon breaks off, not having the triangular structure’s support. This means that you are now left to land the undercarriage without a wing, while your wing floats gently to Mother Earth, by which time you are dead!
AVOIDING PREMATURE DEATH
As you can see, the prime factors causing a whipstall are the sudden loss of thrust in a very steep climb of 45° or more.
Therefore, never climb out at more than 40° in your trike. (A sudden loss of thrust at this lower angle would only cause a mild and easily recoverable stall).
There are however times when you find yourself in a climb steeper than you anticipated.
These are:
After recovering from a steep turn in which you did cot control your sideslip, and your airspeed increased close to VNE and come out of the turn with a higher power setting.
AVOID THIS by controlling your sideslip, watching your airspeed, and recovering passively, from the side slipping turn with a low enough power setting not to go straight into a climb!
The other situation is when you pull the bar in, apply full power and do a “Shoot-up!” The aircraft, being ultra light and the wing being super efficient and the engine being very powerful, the aircraft will go into a radically steep climb. (These are fun and they are enjoyed by many pilots -/ but note that most of our fellow aviators who had a sudden loss of thrust in these radical climbs are no longer with us)
AVOID THIS by not doing these radical “shoot-ups”. If you can’t resist the temptation of a “shoot-up” then do not apply full power when you pull the wing in. Rather pull the wing in, and then with sufficient power to maintain straight and level flight gain airspeed, gently feed the bar forward to alter pitch, (not more than 40°), slowly apply power to maintain the climb while easing the bar back in, so as to climb out with a low angle of attack and good airspeed!
You might however one day find yourself in a steep attitude for some unforeseen reason, in which you fear you might do a whipstall, DO NOT, because of fright, cut power. Keep the power setting that got you there, push the bar sideways, which will initiate a “stall turn”, As the aircraft turns, and goes into a nose down attitude, reduce your power setting and recover straight and level flight.
TO RECAP
Whipstalls are caused by sudden loss of thrust in radical climbs.
1. DO NOT climb at and angle more than 40°.
2. DO NOT do radical “shoot-ups”
3. RECOVER passively and gently after side slipping turns
4. If you find yourself in a potential whipstall situation, keep the power setting, initiate a “stall turn”, then recover to straight and level flight.
Fellow aviators, whipstalls can and have killed people/ To avoid premature death, respect the immense destructive forces involved, never climb out with steeper than 40° and apply the above avoidance techniques.
I appeal to the weightshift instructors to make sure that their students understand clearly the hazards, the basic aerodynamics and avoidance techniques involved in whipstalls. It is not necessary to loose even one more fellow pilot to a whipstall
Jean d’Assonville
Luck-The moment when preparation meets opportunity.
"Whether you think you can or you think you can't, you're right." -Henry Ford
"Opportunity Is Missed By Most Because It Is Dressed in Overalls and Looks Like Work." - Thomas Alva Edison
BUSHPILOTS FLY TAILDRAGGERS
Failure is not the opposite of success, it is the stepping stone for success
"Whether you think you can or you think you can't, you're right." -Henry Ford
"Opportunity Is Missed By Most Because It Is Dressed in Overalls and Looks Like Work." - Thomas Alva Edison
BUSHPILOTS FLY TAILDRAGGERS
Failure is not the opposite of success, it is the stepping stone for success
Re: The Danger of the Whipstall
Thanks KFA, I really appreciate the posting.
Is there a site where I can view the related diagrams? Just goes to show, My idea of what causes a whipstall are radically different from those in the know.
The diagrams will def help me and others understand this fully.
Is there a site where I can view the related diagrams? Just goes to show, My idea of what causes a whipstall are radically different from those in the know.
The diagrams will def help me and others understand this fully.-
KFA
- Toooooo Thousand
- Posts: 2789
- Joined: Mon Jun 19, 2006 8:09 pm
- Location: Now at Petit (FARA)
- Contact:
Re: The Danger of the Whipstall
I have the word document showing all the pics but cannot get them to show here, they are too big. Will try making a pdf and then posting.
What it boils down too is that if the nose is pitched up at a very high angle AOA and you loose power, the normal reaction will be too pull back hard on the bar. Because of this high AOA you have too get the bar way back against your chest to get the plane to actually accelerate. The danger then lies in that your engine can overtake you overhead and you start a forward tumble that you cannot recover from. The ONLY way to recover or save the situation IF you have enough height is too bank steeply to one side, this will then result in a stall turn with a resulting dive from which you can recover if you have enough height left.
What it boils down too is that if the nose is pitched up at a very high angle AOA and you loose power, the normal reaction will be too pull back hard on the bar. Because of this high AOA you have too get the bar way back against your chest to get the plane to actually accelerate. The danger then lies in that your engine can overtake you overhead and you start a forward tumble that you cannot recover from. The ONLY way to recover or save the situation IF you have enough height is too bank steeply to one side, this will then result in a stall turn with a resulting dive from which you can recover if you have enough height left.
Luck-The moment when preparation meets opportunity.
"Whether you think you can or you think you can't, you're right." -Henry Ford
"Opportunity Is Missed By Most Because It Is Dressed in Overalls and Looks Like Work." - Thomas Alva Edison
BUSHPILOTS FLY TAILDRAGGERS
Failure is not the opposite of success, it is the stepping stone for success
"Whether you think you can or you think you can't, you're right." -Henry Ford
"Opportunity Is Missed By Most Because It Is Dressed in Overalls and Looks Like Work." - Thomas Alva Edison
BUSHPILOTS FLY TAILDRAGGERS
Failure is not the opposite of success, it is the stepping stone for success
Re: The Danger of the Whipstall
KFA
Thanks for the post! Always good to get to the 'meat' of an issue without too much speculation and arm chair advice.
Forgive my ignorance, but is this a danger only for trikes, or any aerie?
Not sure whether there is copyright on this material, but as per Bundy's request, it seems you can download the doc here:
http://microlighters.co.za/download/fil ... d3ab520c25
Else search for it on Google, see:
http://www.google.com/search?q=Jean+d%E ... ox&ie=&oe=
Thanks for the post! Always good to get to the 'meat' of an issue without too much speculation and arm chair advice.
Forgive my ignorance, but is this a danger only for trikes, or any aerie?
Not sure whether there is copyright on this material, but as per Bundy's request, it seems you can download the doc here:
http://microlighters.co.za/download/fil ... d3ab520c25
Else search for it on Google, see:
http://www.google.com/search?q=Jean+d%E ... ox&ie=&oe=
Len M
The knack [to flying] lies in learning how to throw yourself at the ground and miss.
The knack [to flying] lies in learning how to throw yourself at the ground and miss.
Re: The Danger of the Whipstall
Many Thanks Guys!
-
John Young
- The Boss
- Posts: 1973
- Joined: Tue May 24, 2005 8:38 am
- Location: Jacksonville, Florida, USA
The Danger of the Whipstall
Hi Bundy,
If you view your feet being "higher" than the horizon, you are out of the envelope.
Don't go there. One view of this well shown clip will persuade you to keep your feet "below" the horizon.
http://www.youtube.com/watch?v=U_vbrMUCuZE
Regards
John N????
If you view your feet being "higher" than the horizon, you are out of the envelope.
Don't go there. One view of this well shown clip will persuade you to keep your feet "below" the horizon.
http://www.youtube.com/watch?v=U_vbrMUCuZE
Regards
John N????
Was a sEXY trike. Now registered as N457YJ
Re: The Danger of the Whipstall
Geez John, you can say that again. That clip is damn scary stuff.
When doing precautionary landings/runway inspections, I have developed the habit of flying very low over the target area with high engine power and the bar in. IE lots of speed while maintaining my height. I have done this because I believed that if anything suddenly flew in front of me, for example a guineafowl or warthog that came running into view, I would be able to climb away very quickly with the speed I had in my pocket. I realise, now that I fully understand how the whipstall works, that I have been putting myself in serious danger!
Will definately be a lot more cautious and will change the way I do this from now on. I know a lot of pilots who do this kind of lowfly, I really hope they read this as well. What bugs me is that I learnt this technique from my instructor!
As they say.. now that Ive got my license, the learning really starts.
When doing precautionary landings/runway inspections, I have developed the habit of flying very low over the target area with high engine power and the bar in. IE lots of speed while maintaining my height. I have done this because I believed that if anything suddenly flew in front of me, for example a guineafowl or warthog that came running into view, I would be able to climb away very quickly with the speed I had in my pocket. I realise, now that I fully understand how the whipstall works, that I have been putting myself in serious danger!
Will definately be a lot more cautious and will change the way I do this from now on. I know a lot of pilots who do this kind of lowfly, I really hope they read this as well. What bugs me is that I learnt this technique from my instructor!
As they say.. now that Ive got my license, the learning really starts.
-
nicow
- The Big Four K
- Posts: 5052
- Joined: Tue May 24, 2005 7:09 am
- Location: Mooketsi,Duiwelskloof
- Contact:
Re: The Danger of the Whipstall
Thanks for all the info
-
MPL Pilot
- Whats the right frequency?
- Posts: 275
- Joined: Sun Jun 28, 2009 9:33 pm
- Location: Hartbeespoort
Re: The Danger of the Whipstall
Thank you for the info KFA, it is scary to think a person can get into a potentialy fatal situation just
because of a lack of knowlage.
I had a 582 fitted on my trike, and on take off at full power it feels like the thrust is pushing the undercarriage forward, toward the front of the wing, which
get me in a high pitch position on the undercarriage.
After reading this, I am so thankfull
Pierre
because of a lack of knowlage.
I had a 582 fitted on my trike, and on take off at full power it feels like the thrust is pushing the undercarriage forward, toward the front of the wing, which
get me in a high pitch position on the undercarriage.
After reading this, I am so thankfull
Pierre
If you fail.... get up and try again. That is the only way to succeed!
ZS-VMS, ZU-RGG, ZU-FWY
ZS-VMS, ZU-RGG, ZU-FWY
-
Biggles
- Pilot in Command
- Posts: 770
- Joined: Wed Nov 02, 2005 12:29 pm
- Location: Cape Town/ Namibia
- Contact:
Re: The Danger of the Whipstall
Bundy, when flying low you should be at a higher than cruize speed with the bar in. So that you have options if you have an engine out or a have to climb rapidly.Bundy wrote:Geez John, you can say that again. That clip is damn scary stuff.
When doing precautionary landings/runway inspections, I have developed the habit of flying very low over the target area with high engine power and the bar in. IE lots of speed while maintaining my height. I have done this because I believed that if anything suddenly flew in front of me, for example a guineafowl or warthog that came running into view, I would be able to climb away very quickly with the speed I had in my pocket. I realise, now that I fully understand how the whipstall works, that I have been putting myself in serious danger!
Will definately be a lot more cautious and will change the way I do this from now on. I know a lot of pilots who do this kind of lowfly, I really hope they read this as well. What bugs me is that I learnt this technique from my instructor!
As they say.. now that Ive got my license, the learning really starts.
Whipstalls are a result of a combination of high attitude and loss of thrust.
I want to add a senario that I heard: If in an improper power-off stall recovery and the bar is pulled back too far and fast you can enter a whip stall.
Trike pilot
Aerotrike Cobra
ZU-DLP
Winelands FAWN
Aerotrike Cobra
ZU-DLP
Winelands FAWN
Re: The Danger of the Whipstall
John
Had a look at the video for the first time today... That is SCARY!!!!
Len M
The knack [to flying] lies in learning how to throw yourself at the ground and miss.
The knack [to flying] lies in learning how to throw yourself at the ground and miss.
-
John Young
- The Boss
- Posts: 1973
- Joined: Tue May 24, 2005 8:38 am
- Location: Jacksonville, Florida, USA
The Danger of the Whipstall
Hi,Biggles wrote:If in an improper power-off stall recovery and the bar is pulled back too far and fast you can enter a whip stall.
Negative on the "whip stall" in this scenario. Rather you could induce a forward tumble which would also be fatal.
Regards
John N????
Was a sEXY trike. Now registered as N457YJ
-
Biggles
- Pilot in Command
- Posts: 770
- Joined: Wed Nov 02, 2005 12:29 pm
- Location: Cape Town/ Namibia
- Contact:
Re: The Danger of the Whipstall
Ah, true getting my fatal senarios mixed up...John Young wrote:Hi,Biggles wrote:If in an improper power-off stall recovery and the bar is pulled back too far and fast you can enter a whip stall.
Negative on the "whip stall" in this scenario. Rather you could induce a forward tumble which would also be fatal.
Regards
John N????
Trike pilot
Aerotrike Cobra
ZU-DLP
Winelands FAWN
Aerotrike Cobra
ZU-DLP
Winelands FAWN
Re: The Danger of the Whipstall
So in the event of me practicing no-power stalls. Should I gently pull back my bar when the A/C reaches the stall curve to initiate speed and recovery?
From what I've been tought, when entering a no-power stall your angle must not exceed 45degrees and the downwards angle must aswell not exceed 45 degrees.
From what I've been tought, when entering a no-power stall your angle must not exceed 45degrees and the downwards angle must aswell not exceed 45 degrees.
Who is online
Users browsing this forum: No registered users and 14 guests