Let’s discuss facts about stall-spin
07-19-2009, 11:33 PM
#1
Thread Starter
Let’s discuss facts about stall-spin
I would like to discuss facts about stall-spin, which has bitten more than one pilot, with all the interested members.
This is a very common type of accident, which ends in disaster each time it happens at low altitude.
Most of us are familiar with a regular wing stall; some also test their models in order to get familiar with the attitude and speed at which a regular stall happens.
This is useful for knowing the limits when flying low and slow, which is more frequent during landing approaches that follow a more or less straight line.
A stall-spin is sneaky and more difficult to predict, especially by an inexperienced pilot.
This particular type of wing stall is associated to turns and centrifugal force.
That centrifugal force is equivalent to adding weight to the model and increasing the wing loading during the time any turn lasts.
In order to turn without loosing altitude, the elevator needs to be deflected up.
By doing this, the tail pushes down, forcing the AOA of the wing to increase.
That way, we are trading air speed by more wing lift to stay level.
In the meanwhile, we have fed ailerons, which cause the outer wing to increase the AOA (angle between leading edge and tip of down elevator and air stream) and the inner wing to reduce the AOA.
The plane rolls and stays rolled because the outer wing lifts more than the inner wing.
The rudder is also deflected towards the center of the turn, in order to achieve a coordinated turn.
All these deflected surfaces slow the model more by increasing turbulence and friction (drag).
The tighter the turn is, more deflection of the control surfaces is needed (in order to achieve a higher AOA for the wings), and the higher the centrifugal force gets; hence, the wing loading grows (our model gets virtually heavier).
If power is not added, the model slows down even more.
In fact, we now have a heavier model, flying slower and at a higher AOA; all these are bad things when the model is flying too close to the ground.
The wings will only support the weight of the model until they reach their critical or stall AOA.
This angle varies for each airfoil, and 12 to 15 degrees are common.
If the tail forces the wings to overpass that angle at which the air stream hits the airfoil of the wings, the lift reduces suddenly, almost disappearing, for practical flight.
The drag goes crazy, slowing the plane much, and the aileron control goes away.
Returning to our turn, we may be very close to that critical AOA; however, it may be difficult to estimate due to the attitude and non-lineal trajectory of the model.
If at that point, the AOA of the inner wing rises, due to our down aileron input to reduce the bank, due to a gust, sudden engine torque increment, etc., the inner wing will stall, and a spin will follow.
The outer wing will go faster, keeping its lift, while the stalled inner wing will drag behind.
Immediate return to neutral of all the control surfaces may save the model, if enough height is available.
This will do the trick by reducing the AOA of the wing and by increasing the air speed until airflow over the stalled wing and control is regained.
Following, I show some interesting data about banking to turn:
Per angle of banking, the wing loading due to centrifugal force (virtual weight of the model) increases as follows:
For a 20 degree bank the force increases in 6%
For a 30 degree bank the force increases in 15%
For a 40 degree bank the force increases in 30%
For a 50 degree bank the force increases in 56%
For a 60 degree bank the force increases in 200%
For a 70 degree bank the force increases in 294%
As you can see, the increments in wing loading are not directly proportional to the increments in the angle of bank.
Why is this rapidly increasing force important in a stall-spin?
The weight that any wing can lift grows linearly with the AOA, until it becomes zero beyond the critical (stall) AOA, as well as it grows in square proportion with the air speed flowing around it.
For any straight flight in balance, the lift of the wing must equal the weight of the model.
In the same way, for any turning flight in balance, the lift of the wing must equal the virtual weight of the model (actual weight plus centrifugal force).
In other words, the wings of a model turning level while banking at 60 degrees must lift twice as much as they would lift when flying straight and level, according to the data shown above.
For either straight or turning flight in balance, when air speed decreases, the AOA must increase.
But the limit to this rule is the stall or critical AOA.
The only way to sustain flight just before reaching the AOA is by increasing the air speed.
For a light model, that necessary air speed is not much (remember how lift depends on AOA and square of air speed).
However, for a heavy model, that air speed needs to be high, or simply, the model will descend because the weight will be higher that the lift produced by that air speed.
As the virtual weight of our banking model increases, the MINIMUM air speed to sustain the turning flight also increases.
In other words, just under the stall AOA, we can fly our models slower in straight flight than in turning flight.
The steeper bank requires higher air speed in order to avoid a stall-spin to bite us.
For the same reason, ailerons should not be used to correct direction while landing slow and being the wings very close to the critical AOA.
The subject is now open for discussion, which I believe that will be beneficial for many of us, frustrated by past stall-spins, or just potential victims.
This is a very common type of accident, which ends in disaster each time it happens at low altitude.
Most of us are familiar with a regular wing stall; some also test their models in order to get familiar with the attitude and speed at which a regular stall happens.
This is useful for knowing the limits when flying low and slow, which is more frequent during landing approaches that follow a more or less straight line.
A stall-spin is sneaky and more difficult to predict, especially by an inexperienced pilot.
This particular type of wing stall is associated to turns and centrifugal force.
That centrifugal force is equivalent to adding weight to the model and increasing the wing loading during the time any turn lasts.
In order to turn without loosing altitude, the elevator needs to be deflected up.
By doing this, the tail pushes down, forcing the AOA of the wing to increase.
That way, we are trading air speed by more wing lift to stay level.
In the meanwhile, we have fed ailerons, which cause the outer wing to increase the AOA (angle between leading edge and tip of down elevator and air stream) and the inner wing to reduce the AOA.
The plane rolls and stays rolled because the outer wing lifts more than the inner wing.
The rudder is also deflected towards the center of the turn, in order to achieve a coordinated turn.
All these deflected surfaces slow the model more by increasing turbulence and friction (drag).
The tighter the turn is, more deflection of the control surfaces is needed (in order to achieve a higher AOA for the wings), and the higher the centrifugal force gets; hence, the wing loading grows (our model gets virtually heavier).
If power is not added, the model slows down even more.
In fact, we now have a heavier model, flying slower and at a higher AOA; all these are bad things when the model is flying too close to the ground.
The wings will only support the weight of the model until they reach their critical or stall AOA.
This angle varies for each airfoil, and 12 to 15 degrees are common.
If the tail forces the wings to overpass that angle at which the air stream hits the airfoil of the wings, the lift reduces suddenly, almost disappearing, for practical flight.
The drag goes crazy, slowing the plane much, and the aileron control goes away.
Returning to our turn, we may be very close to that critical AOA; however, it may be difficult to estimate due to the attitude and non-lineal trajectory of the model.
If at that point, the AOA of the inner wing rises, due to our down aileron input to reduce the bank, due to a gust, sudden engine torque increment, etc., the inner wing will stall, and a spin will follow.
The outer wing will go faster, keeping its lift, while the stalled inner wing will drag behind.
Immediate return to neutral of all the control surfaces may save the model, if enough height is available.
This will do the trick by reducing the AOA of the wing and by increasing the air speed until airflow over the stalled wing and control is regained.
Following, I show some interesting data about banking to turn:
Per angle of banking, the wing loading due to centrifugal force (virtual weight of the model) increases as follows:
For a 20 degree bank the force increases in 6%
For a 30 degree bank the force increases in 15%
For a 40 degree bank the force increases in 30%
For a 50 degree bank the force increases in 56%
For a 60 degree bank the force increases in 200%
For a 70 degree bank the force increases in 294%
As you can see, the increments in wing loading are not directly proportional to the increments in the angle of bank.
Why is this rapidly increasing force important in a stall-spin?
The weight that any wing can lift grows linearly with the AOA, until it becomes zero beyond the critical (stall) AOA, as well as it grows in square proportion with the air speed flowing around it.
For any straight flight in balance, the lift of the wing must equal the weight of the model.
In the same way, for any turning flight in balance, the lift of the wing must equal the virtual weight of the model (actual weight plus centrifugal force).
In other words, the wings of a model turning level while banking at 60 degrees must lift twice as much as they would lift when flying straight and level, according to the data shown above.
For either straight or turning flight in balance, when air speed decreases, the AOA must increase.
But the limit to this rule is the stall or critical AOA.
The only way to sustain flight just before reaching the AOA is by increasing the air speed.
For a light model, that necessary air speed is not much (remember how lift depends on AOA and square of air speed).
However, for a heavy model, that air speed needs to be high, or simply, the model will descend because the weight will be higher that the lift produced by that air speed.
As the virtual weight of our banking model increases, the MINIMUM air speed to sustain the turning flight also increases.
In other words, just under the stall AOA, we can fly our models slower in straight flight than in turning flight.
The steeper bank requires higher air speed in order to avoid a stall-spin to bite us.
For the same reason, ailerons should not be used to correct direction while landing slow and being the wings very close to the critical AOA.
The subject is now open for discussion, which I believe that will be beneficial for many of us, frustrated by past stall-spins, or just potential victims.
07-20-2009, 04:04 AM
#3
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RE: Let’s discuss facts about stall-spin
The AoA is directly related to the elevator angle, provided the airplane is stable. Find the specific angle by test flying and don't exceed it at any time. No stall.....no spin....no crash. Attitude/Airspeed doesn't matter. No guessing required.
07-20-2009, 08:02 AM
#4
RE: Let’s discuss facts about stall-spin
Oddly enough if it's light enough - the spin result from a stall is almost impossible - the model just settles
Not theory - actual paractice shows this is true. I just built another Slow Stick - with the wing flattened and the ailerons functional -
wing loading is between 3-4 ozs per sq ft.
It makes an excellent training model for rank beginners -with some help- of course.
Not theory - actual paractice shows this is true. I just built another Slow Stick - with the wing flattened and the ailerons functional -
wing loading is between 3-4 ozs per sq ft.
It makes an excellent training model for rank beginners -with some help- of course.
07-20-2009, 10:25 AM
#5
RE: Let’s discuss facts about stall-spin
combatpig:
We've got your point already (about 4000 times in as many threads and posts).
Even very light airplanes will do this. I agree weight factors in greatly, but before it happens, you're dealing more with physics than weight. It has everything to so with that critical angle of attack, and pushing yourself past it. Then the weight wil bite you for sure.
But with that said, I am not "always" a proponent of lighter = better. It does factor in with the context of the topic though.
Fly a light model sometime, then you will understand. It's very possible to build a good looking model light enough that only an idiot could crash.
Even very light airplanes will do this. I agree weight factors in greatly, but before it happens, you're dealing more with physics than weight. It has everything to so with that critical angle of attack, and pushing yourself past it. Then the weight wil bite you for sure.
But with that said, I am not "always" a proponent of lighter = better. It does factor in with the context of the topic though.
07-20-2009, 11:28 AM
#6
Senior Member
RE: Let’s discuss facts about stall-spin
I think we're talking about stall induced spins here. If I am correct, then without apology, I agree with Dick. I've got a foamie that without a bunch of rudder and a little bit of power added you CAN'T get it to spin or do anything but fall flat and to use a "3d" term here "do an elevator". Unless you induce a spin with rudder and power it just ain't gonna happen. When it stalls there isn't the slightest tendency to spin, it just quits flying and falls flat down. Just my two cents.
07-20-2009, 05:40 PM
#7
RE: Let’s discuss facts about stall-spin
Input 4001.
I do understand the theory
and have studied it ad nauseum.
I also understand that if one has not delved directly into the extreme ends of possible combinations
INCLUDING extremly low weight stuff, the practical aspects are often. disregarded.
In full scale aerobatics and in the wildest military designs
the generally regarded "rules" are pushed beyond what has been taught as the practical window for usable design.
EXAMPLE
Most new fighter designs will not fly without a computer which can predict and correct the NATURAL and NECESSARY instability of the design.
In the little super light foamies -,again , the envelope of weight/area and vectoring power confound the generally accepted parameters,
In full scale unlimited areobatics - the designers and pilots are trying to emulate the flying capabilities of the "foamies .
simply put : low weight is the holy grail and power is never enough.
However , the guidelines you presented are well worth knowing for many current designs.
.
I do understand the theory
and have studied it ad nauseum.
I also understand that if one has not delved directly into the extreme ends of possible combinations
INCLUDING extremly low weight stuff, the practical aspects are often. disregarded.
In full scale aerobatics and in the wildest military designs
the generally regarded "rules" are pushed beyond what has been taught as the practical window for usable design.
EXAMPLE
Most new fighter designs will not fly without a computer which can predict and correct the NATURAL and NECESSARY instability of the design.
In the little super light foamies -,again , the envelope of weight/area and vectoring power confound the generally accepted parameters,
In full scale unlimited areobatics - the designers and pilots are trying to emulate the flying capabilities of the "foamies .
simply put : low weight is the holy grail and power is never enough.
However , the guidelines you presented are well worth knowing for many current designs.
.
07-20-2009, 10:58 PM
#8
Thread Starter
RE: Let’s discuss facts about stall-spin
Light models fly slower than equivalent heavier models; hence, the first ones require less energy to sustain flight than the second ones.
In consequence, a stall – spin should be stronger and more dramatic for the heavier ones.
In some extreme cases, the little forces and speeds involved in the ultra-light flight are insufficient, just by deflection of the elevator, to force the wing even close to the critical AOA.
Unfortunately, not all models can be built that light.
Scale models are a good example.
Models designed to fly in strong winds are another example.
Those are the models that are affected by this type of stall.
Some of the pilots of those relatively heavy models will beneficiate from the discussions of this thread, I hope.
Here are two examples of stall – spin for full scale airplanes:
http://www.youtube.com/watch?v=08D9qDyFG8s
http://www.youtube.com/watch?v=b_cgzbq3vUQ
Scary, isn’t it?
Note that the stall in turns is non-symmetrical.
One half-wing reaches the critical AOA first and the stall begins ONLY for that half.
The stalled condition makes the drag increase rapidly for that half-wing, which slows down and produces minimum lift.
The airplane yaws and rolls around the CG, while noses down pushed by the pitch moment that the stalled half-wing produces.
In the meanwhile, the other half-wing continues flying faster and lifting.
This way, the spin that follows the non-symmetrical stall feeds itself.
The plane falls in a spin which center is close to the tip of the stalled wing, while the non-stalled wing keeps flying fast around that center.
The way out of this condition is to break the arrangement of forces acting over the model in a non-symmetrical way, while the stalled half-wing recovers normal air speed.
In consequence, a stall – spin should be stronger and more dramatic for the heavier ones.
In some extreme cases, the little forces and speeds involved in the ultra-light flight are insufficient, just by deflection of the elevator, to force the wing even close to the critical AOA.
Unfortunately, not all models can be built that light.
Scale models are a good example.
Models designed to fly in strong winds are another example.
Those are the models that are affected by this type of stall.
Some of the pilots of those relatively heavy models will beneficiate from the discussions of this thread, I hope.
Here are two examples of stall – spin for full scale airplanes:
http://www.youtube.com/watch?v=08D9qDyFG8s
http://www.youtube.com/watch?v=b_cgzbq3vUQ
Scary, isn’t it?
Note that the stall in turns is non-symmetrical.
One half-wing reaches the critical AOA first and the stall begins ONLY for that half.
The stalled condition makes the drag increase rapidly for that half-wing, which slows down and produces minimum lift.
The airplane yaws and rolls around the CG, while noses down pushed by the pitch moment that the stalled half-wing produces.
In the meanwhile, the other half-wing continues flying faster and lifting.
This way, the spin that follows the non-symmetrical stall feeds itself.
The plane falls in a spin which center is close to the tip of the stalled wing, while the non-stalled wing keeps flying fast around that center.
The way out of this condition is to break the arrangement of forces acting over the model in a non-symmetrical way, while the stalled half-wing recovers normal air speed.
07-21-2009, 01:26 AM
#10
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RE: Let’s discuss facts about stall-spin
"For the same reason, ailerons should not be used to correct direction while landing slow and being the wings very close to the critical AOA. "
I believe this to be "an old wives tale".
High Plains has it right. Use the ailerons normally throughout the speed range (A of A range, if you like) but fly "in balance" and you will not spin. If you try to turn the aeroplane, using rudder, you increase the likelihood of a spin, since you are flying "out of balance".
I believe this to be "an old wives tale".
High Plains has it right. Use the ailerons normally throughout the speed range (A of A range, if you like) but fly "in balance" and you will not spin. If you try to turn the aeroplane, using rudder, you increase the likelihood of a spin, since you are flying "out of balance".
07-21-2009, 02:49 AM
#11
RE: Let’s discuss facts about stall-spin
.......not only that but it angers the GROUND GODS when we speak so openly about what makes model aircraft fall from the sky....
It' s been so long since I got bit, it was a kit called the "Rainbow Runner" I won at a raffle. Triple tapered wing, lots of dense balsa block everywhere. The plane ended up weighing about 6.5 pounds with 500+ sq. inches of wing. After I stuffed it, I vowed to go back to what I had learned with Control Line design and apply some of it to RC.
It' s been so long since I got bit, it was a kit called the "Rainbow Runner" I won at a raffle. Triple tapered wing, lots of dense balsa block everywhere. The plane ended up weighing about 6.5 pounds with 500+ sq. inches of wing. After I stuffed it, I vowed to go back to what I had learned with Control Line design and apply some of it to RC.
07-21-2009, 10:23 AM
#12
RE: Let’s discuss facts about stall-spin
I never thot a GWS Slow Stick was beyond anybody- but if it is not a known type model to some-I guess it is beyond the realm-
For those who spent their modelling years building flying heavy models - I really suggest (with enthusiasm) that you blow a few bucks on one of these very basic trainers and flatten out the wing and add ailerons
The resultant model is great for showing others how to fly - it is simple to repair and all the laws of flying can be demonstrated the good part is that the accidents are far fewer because the mistakes simply do not result in sudden "departures" so common on with many older types which were really never good trainers.
The larger models I added here -are all fully aerobatic and a couple are very faithful to scale
Scale models do not need to be heavy
the usual problem is that the builders /designers of the models simply have never learned good building skills
these skills are of more value (unfortunately) than an extensive background in aeronautics and aerodynamics.
One of my earlier postulates was that
"if the model is too heavy , none of the rules of flying apply".
For those who spent their modelling years building flying heavy models - I really suggest (with enthusiasm) that you blow a few bucks on one of these very basic trainers and flatten out the wing and add ailerons
The resultant model is great for showing others how to fly - it is simple to repair and all the laws of flying can be demonstrated the good part is that the accidents are far fewer because the mistakes simply do not result in sudden "departures" so common on with many older types which were really never good trainers.
The larger models I added here -are all fully aerobatic and a couple are very faithful to scale
Scale models do not need to be heavy
the usual problem is that the builders /designers of the models simply have never learned good building skills
these skills are of more value (unfortunately) than an extensive background in aeronautics and aerodynamics.
One of my earlier postulates was that
"if the model is too heavy , none of the rules of flying apply".
07-21-2009, 09:50 PM
#15
Senior Member
RE: Let’s discuss facts about stall-spin
ORIGINAL: dick Hanson
I never thot a GWS Slow Stick was beyond anybody- but if it is not a known type model to some-I guess it is beyond the realm-
For those who spent their modelling years building flying heavy models - I really suggest (with enthusiasm) that you blow a few bucks on one of these very basic trainers and flatten out the wing and add ailerons
The resultant model is great for showing others how to fly - it is simple to repair and all the laws of flying can be demonstrated the good part is that the accidents are far fewer because the mistakes simply do not result in sudden ''departures'' so common on with many older types which were really never good trainers.
The larger models I added here -are all fully aerobatic and a couple are very faithful to scale
Scale models do not need to be heavy
the usual problem is that the builders /designers of the models simply have never learned good building skills
these skills are of more value (unfortunately) than an extensive background in aeronautics and aerodynamics.
One of my earlier postulates was that
''if the model is too heavy , none of the rules of flying apply''.
I never thot a GWS Slow Stick was beyond anybody- but if it is not a known type model to some-I guess it is beyond the realm-
For those who spent their modelling years building flying heavy models - I really suggest (with enthusiasm) that you blow a few bucks on one of these very basic trainers and flatten out the wing and add ailerons
The resultant model is great for showing others how to fly - it is simple to repair and all the laws of flying can be demonstrated the good part is that the accidents are far fewer because the mistakes simply do not result in sudden ''departures'' so common on with many older types which were really never good trainers.
The larger models I added here -are all fully aerobatic and a couple are very faithful to scale
Scale models do not need to be heavy
the usual problem is that the builders /designers of the models simply have never learned good building skills
these skills are of more value (unfortunately) than an extensive background in aeronautics and aerodynamics.
One of my earlier postulates was that
''if the model is too heavy , none of the rules of flying apply''.
There's one that does: what goes up must come down...hard
MattK
07-22-2009, 12:01 AM
#16
Senior Member
RE: Let’s discuss facts about stall-spin
ORIGINAL: dick Hanson
Thermals are a real issue-
Thermals are a real issue-
07-22-2009, 12:27 AM
#17
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RE: Let’s discuss facts about stall-spin
ORIGINAL: MTK
>>''if the model is too heavy , none of the rules of flying apply''.
Di...ick,
There's one that does: what goes up must come down...hard
MattK
>>''if the model is too heavy , none of the rules of flying apply''.
Di...ick,
There's one that does: what goes up must come down...hard
MattK
Umm... I think his point was that it won't fly... Make it heavy enough and you have a prop-driven car... and a funny-looking one at that.
07-22-2009, 12:10 PM
#18
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RE: Let’s discuss facts about stall-spin
There are three discussions going on.
One person, the thread starter, is explaining how stalls work.
A couple other people are saying you can avoid all stalls with the right plane.
And one other person is saying you can avoid all stalls with the right kind of flying.
So I'll contribute my views. If you know how to stall your plane right you can have a lot of fun with it.
Also, the idea that a plane needs to be heavier to fly in strong wind is bovine feces.
If the plane is strong enough to fly and has a wing loading low enough to ride the wind, then the wind won't break the plane.
If that same plane has the power to pull through the wind then the plane can go wherever it wants.
One person, the thread starter, is explaining how stalls work.
A couple other people are saying you can avoid all stalls with the right plane.
And one other person is saying you can avoid all stalls with the right kind of flying.
So I'll contribute my views. If you know how to stall your plane right you can have a lot of fun with it.
Also, the idea that a plane needs to be heavier to fly in strong wind is bovine feces.
If the plane is strong enough to fly and has a wing loading low enough to ride the wind, then the wind won't break the plane.
If that same plane has the power to pull through the wind then the plane can go wherever it wants.
07-22-2009, 01:32 PM
#21
My Feedback: (11)
RE: Let’s discuss facts about stall-spin
ORIGINAL: Outlaw308
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Wing leading edges too sharp.
Too much elevator on pull-up.
Insufficient airspeed.
07-22-2009, 03:08 PM
#22
Senior Member
RE: Let’s discuss facts about stall-spin
ORIGINAL: Outlaw308
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Reduce your elevator throw until it doesn't do it any more. Do this on your low rate setting and you'll still have enough throw to do anything else it does that you want it to.
07-22-2009, 03:12 PM
#23
RE: Let’s discuss facts about stall-spin
ORIGINAL: Bax
Plane too heavy (wing loading too high).
Wing leading edges too sharp.
Too much elevator on pull-up.
Insufficient airspeed.
ORIGINAL: Outlaw308
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Wing leading edges too sharp.
Too much elevator on pull-up.
Insufficient airspeed.
The new designs out of China are -believe it or not -often lighter -and better built-than many "builders" can do from scratch!
They won't survive vertical landings but then -what do you really want in a model?
Having custom built some of the scale kits on the market- it has been obvious to me that many kits especially the "warbirds are grossly overweight
On the other hand -they might be heavy but at least - they are fragile.
07-22-2009, 04:49 PM
#24
Senior Member
RE: Let’s discuss facts about stall-spin
ORIGINAL: mjfrederick
Umm... I think his point was that it won't fly... Make it heavy enough and you have a prop-driven car... and a funny-looking one at that.
ORIGINAL: MTK
>>''if the model is too heavy , none of the rules of flying apply''.
Di...ick,
There's one that does: what goes up must come down...hard
MattK
>>''if the model is too heavy , none of the rules of flying apply''.
Di...ick,
There's one that does: what goes up must come down...hard
MattK
Umm... I think his point was that it won't fly... Make it heavy enough and you have a prop-driven car... and a funny-looking one at that.
07-22-2009, 11:08 PM
#25
Senior Member
RE: Let’s discuss facts about stall-spin
ORIGINAL: Outlaw308
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?
Hi I have a 30% Yak that will tip stall while i do a loop even on very low rats can you tel me why?