# Asymmetric wing incidence angles



## gaussianum (Feb 15, 2006)

I've seen all kinds of statistics for aircraft, but I've never seen the differing incidence angles for each wing. They are necessary to counter engine torque rolling effects, as I understand it. They are probably small, which would explain why they are seldom mentioned.

Does anyone have this information, for the wuergers and the Messerschmitts?

Best Regards


----------



## FLYBOYJ (Feb 15, 2006)

gaussianum said:


> I've seen all kinds of statistics for aircraft, but I've never seen the differing incidence angles for each wing. They are necessary to counter engine torque rolling effects, as I understand it. They are probably small, which would explain why they are seldom mentioned.
> 
> Does anyone have this information, for the wuergers and the Messerschmitts?
> 
> Best Regards



What you are referring to is also known as "wash in and wash out." Many aircraft had this designed into them, others could have it adjusted by essentric bushings installed at where the wing or other surfaces mount to the fuselage. If this is published at all it would be mentioned in the aircraft maintenance manual....


----------



## gaussianum (Feb 15, 2006)

Thanks for the quick reply, FlyboyJ.

I guess I'll have to dig deep into original aircraft maintenance manuals...


----------



## Soren (Feb 15, 2006)

The Spitfire and FW-190 both have 2 degree's of washout, while the Bf-109 has none as it doesn't need it because of the slats. Its there to delay tip stalls which can be dangerous.


----------



## evangilder (Feb 15, 2006)

Didn't the F-8 Crusader also have a variable angle of incidence?


----------



## FLYBOYJ (Feb 15, 2006)

evangilder said:


> Didn't the F-8 Crusader also have a variable angle of incidence?



Yep - the whole wing was "Jacked Up" duirng landing...


----------



## gaussianum (Feb 17, 2006)

Soren said:


> The Spitfire and FW-190 both have 2 degree's of washout, while the Bf-109 has none as it doesn't need it because of the slats. Its there to delay tip stalls which can be dangerous.



Thanks Soren

After some more research, I don't think washout is what I'm looking for. It changes the wing's stall characteristics, but it doesn't add any net lift to the left wing, since it's symmetric, from what I gather.

My guess is that, when you look at aircraft data, the wing incidence is the average of the left and right wing incidences.

The difference between them is probably under 1 degree, which explains why it is rarely mentioned. I'm going to look for some typical values.

Regards


----------



## Soren (Feb 17, 2006)

No problem Gaus, I haven't been able to find any data on asymmetric wing incidence angles for these aircraft, and Im not sure if they even had this actually.


----------



## FLYBOYJ (Feb 17, 2006)

On some light aircraft I've worked on this is mentioned in the maintenance manuals but seldom mentioned as a value. Cessna uses eccentric bushings (as I mentioned earlier) and you adjust them on the inboard attach fittings. You need to fly the aircraft and do the actual adjustment by trail and error.

I also know some aircraft actually had the vertical stabilizer off centered to counter torque. I believe this was true for the AD Skyraider and I think I heard this to be true for the Corsair. 

A YAK-9 was restored when i was working at Mojave a few years ago, a friend of mine worked on it. When completed an "asymmetry check" was done on the wings and airframe (this is done by hanging plumb-bobs off points on the aircraft and measuring the distance between them) and If I remember that one I actually think there was a twist built into the airframe....


----------



## gaussianum (Feb 17, 2006)

FLYBOYJ said:


> I also know some aircraft actually had the vertical stabilizer off centered to counter torque. I believe this was true for the AD Skyraider and I think I heard this to be true for the Corsair.



Yes, I think that's the key to the problem. It's probably the stabilizer, not the wings.

You're a pilot aren't you? From your experience as a pilot, or from footage you may have seen, what would happen if a fellow lost his vertical stabilizer? The aircraft would not only yaw, but also roll, wouldn't it?


----------



## Soren (Feb 17, 2006)

FLYBOYJ said:


> On some light aircraft I've worked on this is mentioned in the maintenance manuals but seldom mentioned as a value. Cessna uses eccentric bushings (as I mentioned earlier) and you adjust them on the inboard attach fittings. You need to fly the aircraft and do the actual adjustment by trail and error.
> 
> I also know some aircraft actually had the vertical stabilizer off centered to counter torque. I believe this was true for the AD Skyraider and I think I heard this to be true for the Corsair.
> 
> A YAK-9 was restored when i was working at Mojave a few years ago, a friend of mine worked on it. When completed an "asymmetry check" was done on the wings and airframe (this is done by hanging plumb-bobs off points on the aircraft and measuring the distance between them) and If I remember that one I actually think there was a twist built into the airframe....



Interesting.


----------



## FLYBOYJ (Feb 17, 2006)

gaussianum said:


> FLYBOYJ said:
> 
> 
> > I also know some aircraft actually had the vertical stabilizer off centered to counter torque. I believe this was true for the AD Skyraider and I think I heard this to be true for the Corsair.
> ...



I am a pilot gauss - I think if you lost everything, vert. stab and rudder, you would yaw and roll, no directional control, and probably would spin. If there was something left you might survive if you could counter the directional instability...

A friend of mine was doing crop dusting in Canada a few years ago. He hit power lines and they took off all his vert stab and left half the rudder. The crazy sob actually landed on a road and inspected the damage. He then got back into the aircraft and flew it back to his base!!!! 

I think he was flying an Ayres Thrush, pretty beefy crop duster....


----------



## JonJGoldberg (Feb 18, 2006)

If an aircraft is properly trimmed for cruise flight and we increase thrust then it will climb and if we reduce thrust it will descend. But how this progresses is not at all straight-forward. The reaction to changing power, without the pilot touching the control column, depends on whether the cg is above, below or in-line with the line of thrust.

For aircraft with a very high power-to-weight ratio, the possibility of a torque stall exists. I see the most visually striking likely scenario as a sudden application of full power in an aborted landing, where the airspeed has been allowed to decay below the safety speed. The torque of the engine and inertia of the large heavy propeller tends to twist the aircraft around the propeller shaft and the consequent roll may increase the AoA of the down-going wing past the critical AoA. If that happens the wing loses lift, accelerating the roll and the aircraft loses height very rapidly.

Since both conditions reflect the cause of what you believe requires remedy by differences in wing incidence, as you are looking for supporting evidence, I’d like to offer the possibility that since both reasons for asymmetrical wing incidence are within the control of the pilot, are highly variable, it is impossible to find an asymmetrical fixed wing incidence that offers a better soultion to this 'problem' than a symmetrical one; or if it is possible, the design is flawed in a major way.

There was a NASA ‘asymmetrical wing’ study, and an aircraft built, I do not recall it’s name, that featured a ‘shoulder’ or parasol wing that pivoted as a single entity, making the wing asymmetrical to induce great increases in turn performance.

As for the tail off set thing, I’ll look into it, and repot if I find something, but I doubt I will, for the same reason given to the wings.

Airframes with built in ‘twist’ as mentioned and ‘measured’ in postings above, are usually easily found in aircraft on the ground as the airframe is usually ‘straight’ only when in level non-inverted flight at 1G, at specified ‘normal weight, speed density air’. The ‘twist’ is the built in airframe ‘s response to being ‘unloaded’, or they are signs of an over stressed, or improperly serviced aircraft; or it is a B&V asymmetrical design.

I’m glad to see that it has been realized; a rudder is not there to off-set torque, but is generally used to correct ‘slew’. I believe that since ‘normal’ flight means non-inverted, some of us may need reminding of the fact that the lines of force from effects of engine/prop torque may not necessarily be correctable by off-setting elevators, wings, or rudders, alone; and since there should only be a need to correct for ‘normal’ flight occurrences, where there steady application of torque can be ‘trimmed’ by using all three controls, or at times easier still the flight stick rudder pedals, as it becomes one of the many ‘factors’ involved in maintaining ‘stable’ flight; or we must be talking of a ‘winged’ aircraft such as the F-5U ‘Flapjack’, where the torque effects were too complicated to overcome, ‘till recently. If we are talking of helicopters… please disregard.


----------



## FLYBOYJ (Feb 18, 2006)

JonJGoldberg said:


> The ‘twist’ is the built in airframe ‘s response to being ‘unloaded’, or they are signs of an over stressed, or improperly serviced aircraft; or it is a B&V asymmetrical design.



I don't quite undertand what you're trying to say, but I could tell you there are a great many aircraft built with a "twist" within their structure. Asymmetry ckecks are done after major repairs or after a hard landing. Some manufactures have numbers to verify if the aircraft is "straight" or out of tolerance



JonJGoldberg said:


> I’m glad to see that it has been realized; a rudder is not there to off-set torque, but is generally used to correct ‘slew’. .



The rudder coordinates a turn and maintains directional stability, period - flying 101


----------



## gaussianum (Feb 18, 2006)

JonJGoldberg said:


> Since both conditions reflect the cause of what you believe requires remedy by differences in wing incidence, as you are looking for supporting evidence, I’d like to offer the possibility that since both reasons for asymmetrical wing incidence are within the control of the pilot, are highly variable, it is impossible to find an asymmetrical fixed wing incidence that offers a better soultion to this 'problem' than a symmetrical one; or if it is possible, the design is flawed in a major way.



This is where I got the asymmetric wing incidence information:

http://www.djaerotech.com/dj_askjd/dj_questions/propeffects.html

Don Stackhouse says:



> Torque tries to roll the airplane. Theoretically you counteract it with some aileron, although for most airplanes the amount of aileron required to do this is almost too small to notice. In some cases the airplane may be rigged with a little more incidence on one wing relative to the other to help counteract torque, although this is rare (it tends to create some funny stall characteristics). Airplanes with way too much power and too little airplane, such as WW II fighters and some aerobatic airplanes are some exceptions.



From what you are saying, torque is always counteracted by the pilot; so, when the craft is flying straight and level, at cruise speed, one feels no torque because the ailerons are adjusted to compensate for it. So, when the controls are neutral, the ailerons are already off-centred to begin with?,



> I’m glad to see that it has been realized; a rudder is not there to off-set torque, but is generally used to correct ‘slew’. I believe that since ‘normal’ flight means non-inverted, some of us may need reminding of the fact that the lines of force from effects of engine/prop torque may not necessarily be correctable by off-setting elevators, wings, or rudders, alone;(...)



On another forum, and also from the DJ Aerotech pages, I learned that the stabilizer has an angle, relative to the craft's roll axis.

Someone also told me that the Ju-88's stabilizer was an airfoil.

Making a vector diagram, I can conceive of a large vertical airfoil's torque counteracting the engine torque. But the main contribution would probably be a yawing one, not rolling.

I think the propwash itself counteracts a bit the engine torque. But that is not enough; when you are taking off, you feel both a yawing and rolling force to the left, with a clockwise-rotating engine, from the pilot's viewpoint. The yawing is caused by the propwash hitting the tail, but the rolling is to the left, so the engine is dominating.

But you don't feel the roll, at cruise speed. Unless the stabilizer acts as a wing, or the wings are asymmetric, or the controls (ailerons) are off centered to begin with, I can't see how torque is counteracted in such a situation.

Maybe you're right; the ailerons are probably already trimmed from the start.

Perhaps FlyboyJ could confirm that?

Great story you told earlier, by the way.Typical pilot heroics


----------



## FLYBOYJ (Feb 18, 2006)

gaussianum said:


> This is where I got the asymmetric wing incidence information:
> 
> http://www.djaerotech.com/dj_askjd/dj_questions/propeffects.html
> 
> ...



Here's a few things I'll try to answer based on your post...

On takeoff, steep turns and at high angles of attack (approaching stall) is where you're going to really feel torque on an aircraft with harmonized controls. On light planes (the majority I fly) you will hold in right rudder during take off and while performing what you call a take off stall. In a steep right turn you will need less right rudder because of p-factor and the opposite when you go right.

Some aircraft do have the ailerons adjusted so they too are counteracting torque, and again this could also be achieved by "wash-in/ wash out." Through out all this the rudder is used to maintain directional stability and coordinate a turn...


----------



## JonJGoldberg (Feb 18, 2006)

FLYBOYJ: Posted: Sat Feb 18, 2006 6:57 pm
..."The rudder coordinates a turn, period - flying 101."

Tell that to the Wind or a '47 pilot during take off, or the unlucky pilot caught in a spin, see if they buy this...

In low power aircraft, and gliders a long established means in controlling the longitudinal axis is to use a fin, or vertical stabilizer, which has a symmetrical airfoil section or just a flat plate, mounted at the rear of the aircraft and which applies a restoring moment to realign the longitudinal axis with the airflow. Note that restoring moment does not realign the aircraft with its original flight path; after restoration the aircraft will be aligned with a different flight path depending on the amount of original displacement.

If you want to control these forces you build a rudder. The rudder is the control surface attached to the fin and is the vertical equivalent of the elevators. Pressure on the left pedal causes the rudder to deflect to the left so that the fin/rudder act together as a cambered airfoil producing an aerodynamic force pushing the tail to the right and consequently the nose swings left, i.e. the aircraft yaws left (yaw is a much better tem than slew; I apologize for its use in my previous post). The amount of yaw, at a given airspeed, is dependent on the degree of rudder deflection of course it is primarily dependent on the moment arm and rudder area. The aircraft will continue yawing if the rudder deflection is held by the pilot but, as the aircraft turns, the wing on the outside of the turn must be moving faster than the inner wing and thus generates more lift. The increased lift will raise the outer wing and the aircraft will enter a banked turn, but will tend to be skidding out because the bank angle will not be correct for the turn as we know that that only one bank angle will produce the desired radius or rate of turn for a particular airspeed (I do not know this to be fact, but slipping skidding are some of my most favorite ways to induce a miss by my adversary, while flying a sim, because I show one bank angle, but perform a maneuver more suitable for another). 

Because of drag and other effects, aircraft perform much better if their longitudinal axis is accurately aligned with the flight path or the relative direction of airflow. If not aligned then the aircraft velocity will have both a forward component and a slight lateral component. That bodily sideways movement is called slip or skid. Flying instructors may use the expressions slip and skid in situations when the airplane is banked and is ‘over-rudder-ed’ towards the lower wing (skidding) or ‘under-rudder-ed’ towards the lower wing (slipping).

FlyboyJ you are referring to this, I hope, nothing personal now… but to you we are done right? Wrong…

In high power aircraft, yaw (much more correct than slew, the use of which I apologize) can be induced by torque, such as during take off, and can only be corrected by the application of rudder, such as in a tail dragger with the rear wheel up…

And what about the guy in a two engine aircraft with one engine out…

I'm not so clear why on landing rudder could not be applied, as in my sim... ‘so’ since I’m no ‘real pilot’, I can not say this is fact, but during landings, especially carrier landings, using rudder is a mighty handy thing, but the in pilot’s manuals, not a one mention rudder during landings, drifting is recommended, even in cross winds.

gaussianum,
I gotta check into you post, but with regard to control settings being at 'neutral', what do mean? If the ailerons were ' off-centered' to begin with, for the reasons you state, or imply the posting states, why would there be a need for adjustment at all? So no the adjustment, or trim to the 'neutral' controls are due to the real time 'exact' requirements, to compensate for… torque, and or other factors, not because they are off center, but because they are on center.

Anyway some images from flight manuals downloaded or purchased that seem relevant…


----------



## FLYBOYJ (Feb 18, 2006)

JonJGoldberg said:


> FLYBOYJ: Posted: Sat Feb 18, 2006 6:57 pm
> ..."The rudder coordinates a turn, period - flying 101."
> 
> Tell that to the Wind or a '47 pilot during take off, or the unlucky pilot caught in a spin, see if they buy this...


JJ - you're making this more difficult than what it actually is! A 47 pilot on take off is experiencing P factor, he squeezes in right rudder - he's controlling DIRECTIONAL STABILITY!!!  

If you get into an accidental spin, its because you didn't apply enough right rudder and listen, here it is again CONTROL DIRECTIONAL STABILITY!!!  



JonJGoldberg said:


> In low power aircraft, and gliders a long established means in controlling the longitudinal axis is to use a fin, or vertical stabilizer, which has a symmetrical airfoil section or just a flat plate, mounted at the rear of the aircraft and which applies a restoring moment to realign the longitudinal axis with the airflow. Note that restoring moment does not realign the aircraft with its original flight path; after restoration the aircraft will be aligned with a different flight path depending on the amount of original displacement.


In a low power aircraft, you'll still have p factor...


JonJGoldberg said:


> If you want to control these forces you build a rudder. The rudder is the control surface attached to the fin and is the vertical equivalent of the elevators. Pressure on the left pedal causes the rudder to deflect to the left so that the fin/rudder act together as a cambered airfoil producing an aerodynamic force pushing the tail to the right and consequently the nose swings left, i.e. the aircraft yaws left (yaw is a much better tem than slew; I apologize for its use in my previous post). The amount of yaw, at a given airspeed, is dependent on the degree of rudder deflection of course it is primarily dependent on the moment arm and rudder area. The aircraft will continue yawing if the rudder deflection is held by the pilot but, as the aircraft turns, the wing on the outside of the turn must be moving faster than the inner wing and thus generates more lift. The increased lift will raise the outer wing and the aircraft will enter a banked turn, but will tend to be skidding out because the bank angle will not be correct for the turn as we know that that only one bank angle will produce the desired radius or rate of turn for a particular airspeed (I do not know this to be fact, but slipping skidding are some of my most favorite ways to induce a miss by my adversary, while flying a sim, because I show one bank angle, but perform a maneuver more suitable for another).



JJ - listen the rudder controls directional stability and coordinates the turn - its simple....


JonJGoldberg said:


> Flying instructors may use the expressions slip and skid in situations when the airplane is banked and is ‘over-rudder-ed’ towards the lower wing (skidding) or ‘under-rudder-ed’ towards the lower wing (slipping).
> 
> FlyboyJ you are referring to this, I hope, nothing personal now… but to you we are done right? Wrong…


Its actually referring to "Stepping on the ball" and nothing personal...  



JonJGoldberg said:


> In high power aircraft, yaw (much more correct than slew, the use of which I apologize) can be induced by torque, such as during take off, and can only be corrected by the application of rudder, such as in a tail dragger with the rear wheel up…



JJ again you're making this much more complicated than it is - on higher performing aircraft (say a P-47) once the tail is up you're continually squeezing in right rudder and maintaining directional stability, more than likely using the runway center line as reference - its that simple! 


JonJGoldberg said:


> And what about the guy in a two engine aircraft with one engine out…


That's a bit different - it depends if the aircraft has counter rotating engines and if there is a "critical engine." I could explain that on another post....



JonJGoldberg said:


> I'm not so clear why on landing rudder could not be applied, as in my sim... ‘so’ since I’m no ‘real pilot’, I can not say this is fact, but during landings, especially carrier landings, using rudder is a mighty handy thing, but the in pilot’s manuals, not a one mention rudder during landings, drifting is recommended, even in cross winds.


You do use the rudder on landing and especially in cross winds, listen carefully, here comes that magic term - "Directional stability" Pilot 101...
Most high performance pilots manuals are not going to go into on how much rudder you shuld apply on landing, you lean that as a student, it like learning how much you lead your car when you turn. By the time you're flying a P-47 (back in the WW2 days) its assumed you're proficent enough to know this....



JonJGoldberg said:


> gaussianum,
> I gotta check into you post, but with regard to control settings being at 'neutral', what do mean? If the ailerons were ' off-centered' to begin with, for the reasons you state, or imply the posting states, why would there be a need for adjustment at all? So no the adjustment, or trim to the 'neutral' controls are due to the real time 'exact' requirements, to compensate for… torque, and or other factors, not because they are off center, but because they are on center.


Remember JJ - not all aircraft have trim around each axis, most light aircraft just have elevator trim. You check the adjustment on them because cables stretch and contract, they will go out and you will feel a difference in the way the plane flies


----------



## JonJGoldberg (Feb 19, 2006)

gaussianum,
Sorry dude!!! This article is very bad news, in my opinion (but FlyboyJ seems to like it, so maybe I should reconsider).

From Your Article
“…The tendency to yaw on takeoff and climb is due almost entirely to P-factor and slipstream effects. The only direct contribution that torque makes to yawing in the early part of takeoff roll is perhaps a slight increase in the rolling friction of one main wheel because the torque is causing it to carry more weight than the other wheel. Strictly speaking, torque applies a rolling moment to the plane, NOT a yawing moment.”

He is trying, for some reason to say that the engine prop are always at a 90 degree angle to the direction of flight, and therefore can only produce a rolling effect. This is not true, thrust angle, and P-factor aside; because although the prop and engine are spinning in the same direction and are affixed to the aircraft in the same location, relative to say our author, the A-36 pilot, sitting in his cockpit, the relationship of the torque forces at play are not the same when viewed from the perspective of say Earth’s gravity, momentum, or rate of change to our aircraft’s direction of travel. For example, when your nose is straight up, as opposed to during take off, the prop has no P-factor, you, the pilot see the effect of torque as being the same as when on the ground in relationship to your aircraft, to an observer planted on the Earth, torque rotation changed from being a vertical force, to one that is horizontal. What is happening to the aircraft is similar to your experience, if you were holding a spinning bicycle wheel by the ends of the axel, as you change rotation, by swiveling (yawing) the axel, from horizontal to vertical, what is happening to our pilot is the view from near center of the axel. 

So I stopped reading from where I ended my quote.

Flyboy J,
Sorry, I’m from NYC, and it’s normal for us to bark a bit more than most over nothing… I think you are an OK guy, and a pilot at that, as is the A-36 pilot, a contributor to G’s referred posting… I am just a self taught pixel playing wanna be... Am I being thick? Help me please…

P-factor I think is can be defined as seen (very cleverly) here… http://yarchive.net/air/airliners/p_factor.html

I’m not trying to say that P-factor is not an included dynamic force in the least; what I am sayin’ is so is prop torque. That rudder is applied not only ‘coordinate a turn’ a phrase I now see on your post to have expanded to include directional stability, which if I saw as included, I honestly didn’t, as it is lacking within my last post, I would not have generated my response, as we would be in agreement for the most part (at 50% my glass is half full). So I would like to apologize for being ‘difficult’.


----------



## FLYBOYJ (Feb 19, 2006)

JonJGoldberg said:


> gaussianum,
> Sorry dude!!! This article is very bad news, in my opinion (but FlyboyJ seems to like it, so maybe I should reconsider).
> 
> From Your Article
> ...



Hey no problem JJ - here's something to think about...

Imagine a line in front of the nose of you re aircraft, like the center line of a runway - whether it be a P-38, P-47, etc. Any maneuver you complete you're going to roll into a desired heading, that being that imaginary line. Because of P-factor, prop torque, cross winds etc, you're as you roll toward that desired heading one of there factors are going to send you "off the line." You coordinate with the rudder....

On landing that imaginary line turns into the runway center line. You may use a combination of aileron and rudder to maintain that center line "right between your legs" if you're sitting in a single seat aircraft - As you go to land and start to flare you slowly "squeeze out" these inputs when you're a few feet above the ground so you don't land with the nose angled when referenced to the runway center line. By not doing that you're planting the landing gear "twisted" and you could damage the landing gear....


Good post of the flight manuals, but like I said earlier they are written for the pilot that has several hundred hours and are not always going to mention thinks like coordinating controls (rudder ) for maintaining directional stability. 

Many WW2 pilots jumped into these beast with just a few hundred hours and sometimes were not proficient (when compared to today's standards) and were already in combat. The biggest non-combat killer back then was spin/ stall and it's still the same for many lower time pilots today.

There's always a joke made about a flight instructor screaming at his student - 'RIGHT RUDDER, RIGHT RUDDER,' or 'STEP ON THE BALL, STEP ON THE BALL,' this emerging from what was shown here...

Remember JJ - I'm from Staten Island, we're "homies" I know where you're coming from!


----------



## gaussianum (Feb 19, 2006)

JonJGoldberg said:


> gaussianum,
> Sorry dude!!! This article is very bad news, in my opinion (but FlyboyJ seems to like it, so maybe I should reconsider).



It's Ok, but I really think you should read the full article. Maybe you're misinterpreting the author, and I suspect, to a significant degree.



> He is trying, for some reason to say that the engine prop are always at a 90 degree angle to the direction of flight, and therefore can only produce a rolling effect.



No aircraft would fly in such a situation. Only a helicopter would. I think you're misinterpreting.



> What is happening to the aircraft is similar to your experience, if you were holding a spinning bicycle wheel by the ends of the axel, as you change rotation, by swiveling (yawing) the axel, from horizontal to vertical, what is happening to our pilot is the view from near center of the axel.



What you are referring to, is gyroscopic motion. Climbing in an aircraft can produce a gyroscopic yawing motion, not a rolling one. Rolling will increase After the craft has started yawing, due to asymmetric wing lift, caused by the yaw itself.

My question has a physical origin. According to Newton's law of Action-Reaction, the torque imparted to the propeller is the opposite to the torque imparted to the airframe by the propeller/shaft. Since the prop rotates (Fast!), there is always a torque acting on the airframe, to make it rotate in the opposite direction. This is not an effect. This is the cause of all torque induced behaviour.

My question is: what force counters it? 

Having the ailerons turned a bit to the right, when the controls are neutral (thus making the left wing generate slightly more lift than the right one), would counter it, but only when the airspeed reaches a certain level, namely cruise speed. This is because wing lift increases with V^2, so a small margin when speed is small, becomes a very large one when speed increases.

Another possibility would be, as the author says, to increase the left wing's incidence angle, relative to the right one.

P-factor only becomes significant when airspeed increases. Stockhouse says that the propwash force is stronger than p-factor at take-off, and although I would like to see the governing equations, I suspect that he is right.

I emphasize that the issue here is how rolling motion is countered, not yawing one.

When you stall, you roll. This means that the tail alone is not enough to counter engine torque. The propwash force is present, wether the aircraft is flying at 0 or 300 Km/h (as long as the engine is on, and the props are rotating, of course).

FlyboyJ, when flying at high speed, does an aircraft have a slight tendency to roll to the right?

Best Regards


----------



## FLYBOYJ (Feb 19, 2006)

gaussianum said:


> My question has a physical origin. According to Newton's law of Action-Reaction, the torque imparted to the propeller is the opposite to the torque imparted to the airframe by the propeller/shaft. Since the prop rotates (Fast!), there is always a torque acting on the airframe, to make it rotate in the opposite direction. This is not an effect. This is the cause of all torque induced behaviour.
> 
> My question is: what force counters it?


Look at the size and mass of the spinning propeller, then look at what's behind this - a much larger mass - the airframe with surfaces generating lift.



gaussianum said:


> Having the ailerons turned a bit to the right, when the controls are neutral (thus making the left wing generate slightly more lift than the right one), would counter it, but only when the airspeed reaches a certain level, namely cruise speed. This is because wing lift increases with V^2, so a small margin when speed is small, becomes a very large one when speed increases.
> 
> Another possibility would be, as the author says, to increase the left wing's incidence angle, relative to the right one.
> 
> ...


You'll roll in a "Power On" stall, and that's why you need right rudder to counteract that and attain "Directional Stability." If you stall the aircraft with the engine at idle, most aircraft break out of the stall straight ahead.
 
Gauss - you've answered many of your own questions, all are correct!



gaussianum said:


> FlyboyJ, when flying at high speed, does an aircraft have a slight tendency to roll to the right? Best Regards



You mean left (as sitting in the cockpit). It depends on the aircraft. Let me tell a story...

I worked on the P-3 for a number of years, in the early 1980s I worked on the production line. Our subcontractor dropped a right wing, it was rebuilt and shipped to our factory. When the aircraft was completed we did an asymmetry check and discovered the wing was slightly crooked (I don't remember the exact details). Lockheed management decided to do some additional testing prior to asking the customer (the USN) to take delivery of it. All parties agreed. Now the P-3 has 4 T56 engines all rotating in the same direction. I was told by the pilots at full speed the P-3 could not be trimmed out, it slightly turned left. This aircraft (with the repaired wing) was flown and at about 470 mph (the P-3s top speed) this aircraft flew straight and level "hands off." Till today I remember one the the flight test engineers saying "we couldn't build aircraft that could do that again if we tried....


----------



## JonJGoldberg (Mar 2, 2006)

Flyboy J, gaussianum you must check out these finds, one I stumbled across hours ago, the other I don't remember how I found it but they are relevant. 

The first http://naca.larc.nasa.gov/digidoc/report/tm/12/NACA-TM-712.PDF, an article from the NACA database (NASA archives), authored in 1933, is a 'technical' review of the Schneider Trophy aircraft.

The other NASA/TM-2004-212045 is titled Manual Manipulation of Engine Throttles for Emergency Flight Control. Shoot, I don't have the E-mail address, and it is a NASA document, I'll await a response from a 'mediator' or other WW2aircraft.net official to tell me weather or not I may attach this .pdf for you to upload, But I will attach some pages, so they may tell me if it is OK.


----------



## gaussianum (Mar 2, 2006)

In the first report, they use two solutions.

First one: counter-rotating engines. The torque of one engine cancels the torque of the other.

Second one: They increase the weight of the right float. This increases the Moment of Inertia of the plane; it shifts the Center of Gravity to the right also, which is not the best of solutions, but it was probably the best one they could find.

In the second report:

All of these seem to be multi-engined aircraft. Some of them seem to be jet-engined.

The asymmetric wing incidence question is mostly related to single-engined, piston-driven (propeller) aircraft.

Best Regards


----------



## FLYBOYJ (Mar 2, 2006)

JonJGoldberg said:


> Flyboy J, gaussianum you must check out these finds, one I stumbled across hours ago, the other I don't remember how I found it but they are relevant.
> 
> The first http://naca.larc.nasa.gov/digidoc/report/tm/12/NACA-TM-712.PDF, an article from the NACA database (NASA archives), authored in 1933, is a 'technical' review of the Schneider Trophy aircraft.
> 
> The other NASA/TM-2004-212045 is titled Manual Manipulation of Engine Throttles for Emergency Flight Control. Shoot, I don't have the E-mail address, and it is a NASA document, I'll await a response from a 'mediator' or other WW2aircraft.net official to tell me weather or not I may attach this .pdf for you to upload, But I will attach some pages, so they may tell me if it is OK.



I posted that NASA report on another link here in this forum in its entirety - I got it from my Father in law, he wrote an emergency procedure for UA on the 737 based on this information. Here's a copy, let me know if it downloads...


----------



## JonJGoldberg (Mar 3, 2006)

Flyboy J...son of a gun, you did post NASA/TM-2004-212045, thanks again. I was not trying at all to take credit, I wanted to share, hope I didn't do something I was not supposed to, or that you took offence too. …Must have been an early senior moment. I suck!!! 

gaussianum… They did much more than weight a float; from the article “…The 1923 Curtiss racers therefore used a weight balance in the float.” “…Subsequent developments revealed the inadequacy of tilis weight balance for larger engines and the same dimensions. As a result, the more modern racer has a flotation gear in which the float loaded additionally at the takeoff is farther away from the plane of symmetry and, in addition, larger than the unloaded float (resistance balance). But even these measures did not always prove sufficient on all racing seaplanes. Thus the propellers of the Supermarine S.6 B had to have a diameter greater than the optimum figure, because at take-off with smaller propellers, it was impossible to keep the seaplane on the course, thus making the take-off altogether impossible.”

So it seems to me they played with lots of stuff. I thought this may be of use to you …an attempt. Since I’m self educated, I just love going off into the deep end... My solutions...


----------



## FLYBOYJ (Mar 3, 2006)

JonJGoldberg said:


> Flyboy J...son of a gun, you did post NASA/TM-2004-212045, thanks again. I was not trying at all to take credit, I wanted to share, hope I didn't do something I was not supposed to, or that you took offence too. …Must have been an early senior moment. I suck!!!



Hey No problem - that report is a bit dry but interesting. I actally had the opportunity to fly a 737 full motion simulator at UAs training center on severl occasions. On a "10 mile final from DIA" my rudder was "locked" and hydraulics were failed. My brother in law was in the right seat, he's a big strong guy so with his muscle (and mine) along with differential throttles, we landed the aircraft, the only damage that occured was the collision with several landing lights as we rolled off the end of the runway at about 20 knots due to the rudder being in full deflection.....


----------



## gaussianum (Mar 4, 2006)

Hi JonJGoldberg,

Congrats for that very nice sketch, I appreciate your work.

Some further thoughts on the measures taken by engineers to reduce engine torque:

-Extending the float away from the axis of symmetry, again increases the Moment of Inertia, and unbalances the aircraft to the right. This has the effect that the torque induced by the left wing is greater than the one generated by the right one, at all speeds, since the lef wing's Center of Gravity is farther away from the plane's Center of Gravity, than the right one's.( nicely convoluted sentence there)

- Making the right float bigger enhances its buyoyancy properties, and the air resistance induces slight yawing torque, that counteracts the usual propeller-caused yaw.

- Making the propeller blades bigger probably increases the volume of the slipstream air column (propwash) hitting the horizontal and vertical stabilizers, thus countering more effectively the aircraft's rolling and yawing tendencies.

Did any of those Schneider Trophy planes have small winglets? 

Best Regards


----------



## JonJGoldberg (Mar 5, 2006)

gaussianum... Thank You.

I reasoned these innovations; I've never seen on a 'Schneider Trophy' aircraft, or any other aircraft, applied as I've shown (in yellow), an asymmetrical retractable rudder, asymmetrical winglet, asymmetrical elevator rudder leading edge slats. I also tilted the camber a bit on the larger float, but I reason someone has done that.

As I've shown, I believe the most effective controls would not be fixed, nor would it be an asymmetrical horizontal mounting of an elevator, or wing. For all the complexities I've shown, I believe that the 'real' aircraft designers were yet even cleverer. For example, as with the P-47, make the trim adjustments available only one side of the wing; then 'autopilot'...

Let me share this site with you The FoilSim II Applet. I've used it to help me visualize, and since it is from NASA, do rough math. It should help all here, Flyboy J you will love this, I should have remembered this site sooner!!! As a bonus, there is lots of other NASA Sim stuff as well!!!

http://www.grc.nasa.gov/WWW/K-12/freesoftware_page.htm


----------



## FLYBOYJ (Mar 5, 2006)

Cool site JJ - lots of neat stuff!


----------



## JonJGoldberg (Mar 14, 2006)

I still can not find that American test aircraft, I can't even remember it's number, the aircraft with the pivoting wing... Anyway found one better. Bad thing about this is, the design was applied as a solution for handling at various speeds, not asymmetrical forces .


----------



## gaussianum (Mar 14, 2006)

That's very interesting JonJ. I've never seen anything like it.


----------



## JonJGoldberg (Mar 15, 2006)

I found it... Matter of time... OK see what I created and posted below... Now check this out; this NASA researcher claims to have 'conceived' the idea.  ... That is why I thought the BV such a find!!!

Go here for a 'quick-time' movie ( http://www.dfrc.nasa.gov/Gallery/Movie/AD-1/HTML/EM-0001-02.html )

This is where I found the pics from there the info... Have fun!!!
( http://www.dfrc.nasa.gov/Gallery/Photo/index.html )

FlyboyJ... Did I find the rock that does not ascribe to the bank angle law? No... But I wonder if this aircraft's bank angle is the same as that of a conventional aircraft of the same span... regardless of it's setting? That is why you see a pic of the cockpit.


----------



## FLYBOYJ (Mar 15, 2006)

Hmmm, no turn and bank or artificial horizon on the instrument panel?!?


----------



## ErangaEddie (Jan 1, 2014)

Can anyone tell me the disadvantage of an asymmetrical wing? please.


----------



## pbehn (Jan 2, 2014)

gaussianum said:


> Yes, I think that's the key to the problem. It's probably the stabilizer, not the wings.
> 
> You're a pilot aren't you? From your experience as a pilot, or from footage you may have seen, what would happen if a fellow lost his vertical stabilizer? The aircraft would not only yaw, but also roll, wouldn't it?



This happened to a 747 in 1985 
Japan Airlines Flight 123 - Ask.com Encyclopedia


----------



## Elmas (Jan 2, 2014)

To counterbalance the torque the Macchi 200-202-205 had wing dimensions slightly different berween left and right wing. The right wing was 4.32 m long, with a chord of 1.17 m at the tip and a weight of 168 kg, while the left measured 4,52 m, with 1.16 m at the tip, with a weight of 185 kg.


----------



## GregP (Jan 2, 2014)

I believe the Bf 109 had asymmetry in the vertical fin. It was airfoiled on one side to help counter torque on takeoff and pretty much flat on the other side. Another method for helping to counter torque is engine mount offset. Many aircraft have a degree or two of downward / left / right thrudt from the engine mount.

Washout actually subtracts a small amount of total lift from the wing, but the benefits return at the stall when the ailerons remain efective as the wing root stalls. Wash-in is backwards, and is not generally desirable.

Usually the wing incidence is quoted as the incidence at the wing root - fuselage joining, not as an average of the entire wing. A great example of wing incidence would be the Bopeing B-52. The wing has a large positive incidence and is so great taht the tail lifts off firsta nd it flies nose down in level flight at low altitude. At it design bombing altitude, it flies levelly.


----------



## waroff (Jan 3, 2014)

on the aicraft single engine or multi(but the propellers turn in same direction)
there are some effects:
- torque, due to drag of blade propeller
- helical wind of propeller
- asymetrical airscrew thrust
- gyroscopic effect

to compensate for these effects :
- torque: aileron trim, lenght of the wings(Macchi), adjustable flap on wingtip(MS406, MB152)

- helical wind: setting of fin(H75, Hawker Hurri, Bf 110, F4Au, Mureaux 11x...) or asymetrical air foil(D520...) + engine setting 1° left and 1°down(D520), 1°26' left and 1° down(MS406), 3° left(MB152)

- asymetrical thrust and gyroscopic effect are when airplane climb and/or change of pitch attitude : trim rudder


----------

