Aces High Bulletin Board
General Forums => Aces High General Discussion => Topic started by: hotcoffe on January 15, 2014, 08:46:18 AM
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How to figure out the direction of the torque in any plane?
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Turn off auto takeoff, push the power up, keep your feet off the rudders and see which way it goes.
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Turn off engine to determine which way the prop rotates. Torque will be in the opposite direction.
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Thnx.
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For the most part, the torque is always to the left. The planes that have torque to the right are: Yak's, Typhoon (Tempest too I think), and Spit 14. I don't think there is another with torque to the right but I'm sure someone will correct me if I'm wrong.
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p38's
semp
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p38's
semp
With both screws turning, the 38 has no torque due to counter rotating props.
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Trivia question,
Does engine torque create a roll or a yaw force?
HiTEch
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Trivia question,
Does engine torque create a roll or a yaw force?
HiTEch
Both! :old:
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Trivia question,
Does engine torque create a roll or a yaw force?
HiTEch
That's sort of a trick question. Taken completely on it's own, torque creates rolling force in single-engine, single propeller aircraft, but not yaw. Yaw is induced from the aerodynamics of airflow rotating around the fuselage due to prop mass airflow and from a non-neutral control surface configuration.
That is to say, torque itself does not induce yaw, but airflow from a turning propeller (which itself causes a rolling tendency) and the trim required to cancel out the effects of torque will cause a yawing tendency, which itself needs to be trimmed for.
That said, there are a few factors of propeller aerodynamics that contribute to yawing tendency.
Airflow from the descending propeller blade will spiral around the aircraft and strike the aircraft's tail, usually on the left side, inducing further left-turning tendency (known as "prop wash").
Lastly, P-factor also produces a yawing tendency due to assymetrical lift produced by the propeller. The angle between the relative wind and the propeller blade differs for the ascending and descending blades when the aircraft is not in a straight-and-level orientation to the relative wind (such as during a climb or descent). During a climb, the downward-moving side of the propeller (as viewed from the rear) has a higher angle of attack than the upward-moving side. This higher angle of attach causes the lift to be greater on the descending side of the propeller, causing the aircraft to yaw towards the opposite direction (again, typically the left). This effect is greatest when angle of attack is large and forward airspeed is low, typically the takeoff phase of flight. The opposite also happens during a slow descent, where the ascending blade has a greater AoA, producing an opposite yawing tendency.
These combine to produce a pronounced yawing tendency (in addition to the rolling tendency), usually to the left (viewed behind the aircraft/propeller).
EDIT: Cuz I had a brainfart and started writing about adverse yaw
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it's a trick. hitech already asked this question a couple of years ago. look it up.
semp
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I would say both roll as a counter to the torque and yaw because the roll creates a vector perpendicular and forward to the planes center of gravity
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I would say both roll as a counter to the torque and yaw because the roll creates a vector perpendicular and forward to the planes center of gravity
I would have guessed the opposite,the torque induces yaw which causes a roll effect... but I'll leave it to the experts to answer.
:salute
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IL2 has torque to the right as well.
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p38's
semp
Only if flying with a single engine and the torque if flying on a single engine doesn't roll the aircraft like in single engine planes, it produces a yaw effect instead. I'm guessing that's most likely due to the 2nd engine.
ack-ack
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Only if flying with a single engine and the torque if flying on a single engine doesn't roll the aircraft like in single engine planes, it produces a yaw effect instead. I'm guessing that's most likely due to the 2nd engine.
ack-ack
Actually the torque produced by the engine on a twin with only one engine running, works the exactly same as a single engine plane does. Physics 101, torque is torque no matter where you apply it to an object.
Thrust on the other hand does produce yaw with a one engine twin.
HiTech
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Actually the torque produced by the engine on a twin with only one engine running, works the exactly same as a single engine plane does. Physics 101, torque is torque no matter where you apply it to an object.
Thrust on the other hand does produce yaw with a one engine twin.
HiTech
Thanks for the explanation, wondered why the Lightning yawed like it does with a single engine.
ack-ack
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African or European?
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The Deadly P-51 Torque Roll:
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.
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Trivia question,
Does engine torque create a roll or a yaw force?
HiTEch
Roll. Yaw comes more from p-factor, gyroscopic precession, and to a lesser degree, spiraling slipstream. Some people reject the latter. In a climb the descending blade takes a bigger bite of air due to its higher AOA than the ascending blade which causes yaw. Precession comes into play with pitch changes, particularly when the tail lifts off the ground for takeoff. (Force applied to the prop is felt 90 degrees ahead in the plane of rotation. Nose comes down. Plane yaws left for Pony, Jug, etc. and right for Spit, Typh, etc..)
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The Deadly P-51 Torque Roll:
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.
P-factor and gyroscopic precession are still an issue for yaw on takeoff, particularly with tail daggers.
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Only if flying with a single engine and the torque if flying on a single engine doesn't roll the aircraft like in single engine planes, it produces a yaw effect instead. I'm guessing that's most likely due to the 2nd engine.
ack-ack
A twin engine plane flying on a single engine will yaw because the engine is pushing on one side of the aircraft. With the engines on the wing, the single engine is applying its force to one side of the center of gravity.
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Only if flying with a single engine and the torque if flying on a single engine doesn't roll the aircraft like in single engine planes, it produces a yaw effect instead. I'm guessing that's most likely due to the 2nd engine.
ack-ack
Accelerated air flow over the wing will increase loft on the side with a running engine, adding roll. Torque also factors in. Depending on which engine has failed it can help or hurt.
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Roll. Yaw comes more from p-factor, gyroscopic precession, and to a lesser degree, spiraling slipstream. Some people reject the latter. In a climb the descending blade takes a bigger bite of air due to its higher AOA than the ascending blade which causes yaw. Precession comes into play with pitch changes, particularly when the tail lifts off the ground for takeoff. (Force applied to the prop is felt 90 degrees ahead in the plane of rotation. Nose comes down. Plane yaws left for Pony, Jug, etc. and right for Spit, Typh, etc..)
Agreed, except that at the start of the take off roll the slipstream is the biggest contributing factor to yaw.
HiTech
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Agreed, except that at the start of the take off roll the slipstream is the biggest contributing factor to yaw.
HiTech
No argument from me on that.
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Precession comes into play with pitch changes, particularly when the tail lifts off the ground for takeoff.
Pick the tail up too soon on a B-17 (real life) and that will be well demonstrated…..and if you have any left crosswind you might find you don't have enough rudder (you do still have adverse yaw and differential power if needed).
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Pick the tail up too soon on a B-17 (real life) and that will be well demonstrated…..and if you have any left crosswind you might find you don't have enough rudder (you do still have adverse yaw and differential power if needed).
Yep you havn't lived unless you understand what happy feet on rudder pedals with pinched but cheeks feels like. I bet once that mass gets rotating in the B17 the lag in stopping it could be quite interesting. Plus I assume hardly any prop wash on the rudder to speak of. Does it like to swing much when setting the tail down after a wheels landing?
HiTech
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Only if flying with a single engine and the torque if flying on a single engine doesn't roll the aircraft like in single engine planes, it produces a yaw effect instead. I'm guessing that's most likely due to the 2nd engine.
ack-ack
actually what I was pointing out was the prior reply where that posting that most planes turn left and rest turn right. which left out the p38.
semp
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Does it like to swing much when setting the tail down after a wheels landing?
HiTech
Not enough to make it memorable, but that was usually more gentle than raising the tail so that might be part of it.
You're right about mass. It's a 60000 pound tail dragged, if you ever let it get pointed the wrong way you are probably going for a ride.
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The Deadly P-51 Torque Roll:
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.
What if the wheel was on a treadmill? I've heard this has a dramatic effect.
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https://m.youtube.com/watch?v=YORCk1BN7QY (https://m.youtube.com/watch?v=YORCk1BN7QY)
Plane on a conveyor belt
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We had a 46 pager on the conveyor topic.
There is much more to the question as you start examining it in detail.
http://bbs.hitechcreations.com/smf/index.php/topic,197189.0.html
HiTech
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Pick the tail up too soon on a B-17 (real life) and that will be well demonstrated…..and if you have any left crosswind you might find you don't have enough rudder (you do still have adverse yaw and differential power if needed).
Never thought of that. Was thinking a C-46 would be hairy. B-17 never even came to mind. Wow.
I remember seeing Chuckie and Texas Raiders "bow" to the crowd from a dead stop so no doubt the tail can come up early. What a wake up call that would be.
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actually what I was pointing out was the prior reply where that posting that most planes turn left and rest turn right. which left out the p38.
semp
For all practical purposes the P-38 because of its handed propeller rotation has two critical engines (not exactly, but close) as opposed to something like a Seminole which almost doesn't. I suppose that helps with maneuverability or something, but sure makes losing either engine a challenge. Don't recall if inward prop rotation was considered but seems on the surface to have been a better idea (I have no idea the impact on thrust, maneuverability, vibration, etc. though). Conventional rotation was a dud. Random thought.
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I remember seeing Chuckie and Texas Raiders "bow" to the crowd from a dead stop so no doubt the tail can come up early.
That would be easy to do with power and brakes. In fact you can "back" a B-17 using brakes and differential power.