View Full Version : Annoying torque loading question, please help...

28th Feb 2006, 18:10
It just occurred to me that this may be regarded as cheating, which is definitely not my intention, I was merely 'researching' the answer you understand as I was very stuck.

Therefore, thread deleted. But thanks to those who replied below!

28th Feb 2006, 18:22
Differentiate between torque (torsional) loads and bending loads then look again.

28th Feb 2006, 18:30
Depends who's flying the thing! :rolleyes:

Not to mention who's landing it! :\

28th Feb 2006, 18:49
The Hosties usually torque the most. :ugh:

28th Feb 2006, 18:55
Always remember being a passenger aboard a coach driving parallel to one of Heathrows runways, watching a Tristar taking off. As the body rotated the wings tips remained parallel to runway for a second or so, then caught up with the rest of the wing, there must have been a fair amount of twisting (torque) experienced by the wing.

28th Feb 2006, 19:51
a) Even if the aircraft is yawing significantly as the tyre touches the runway, the tyre contact patch/es are still more or less directly at the end of the gear leg. What does that suggest that any side loading on the tyre tries to do to the leg?

b) Yes and yes. Big bending loads, considerable torsional loads. Judgement call as to what represents 'significant' I'd say, especially if one is being considered relative to the other.

c) The wings give lift. The elevators, via the horizontal stabilizer, control how much lift, or rather not, the horizontal stabilizer gives. The effort of one relative to the other tries to bend the fuselage between wing and tail.

Use of the rudder applies side loads to the vert' stab' which is, by nature of its attachment point being there, causing it to try to twist that rear section of fuselage by the sideloads trying to rotate the whole vert' stab' around it. Obviously, the wings stop that happening and the fuselage spinning along its length. So, that'd be torsional loading, but whether it's 'significant' before the rudder gives up the impossible task of trying to roll the fuselage and wings over and instead does its aerodynamically easier job and causes/counters yaw is your call.

d) Use of the rudder definitely exerts a torsional loading down the vert' stab'. I'd say it's significant.

e) You mean thrust of the engine being transmitted to the airframe? That'd be trying to bend the pylon in a fore and aft plane. Rotational inertia, or changes of, in the engine will try to bend it side to side. To subject the pylon to torque you'd need to twist the engine, end to end along its horizontal axis. The main thing that'll cause that to happen is aerodynamic effects on/through/around the engine.

Help! Brain fade! Someone pitch in quick and save r44 if I'm talking nonsense. I see why you asked now. The more you think about it, the more you doubt yourself. :=

28th Feb 2006, 19:57
Putting the brakes on will transfer a torque load to the U/C leg. Perhaps that is why the main U/C is mentioned and not the nose or tailwheel.

28th Feb 2006, 20:01
Maybe I fried my brain already but, short of braking only the wheels on one side of the bogie, I can't see how. It's a bending load surely? Maybe if it's braking on a conveyor belt though.... :ugh:

In fact, doesn't 747 mlg have a mechanism which allows quite a large degree of 'steering' (of the passive kind) deflection to allow for yaw? I imagine that mostly helps the tyres not load the leg sideways and try to bend it if the track along which the tyres are pointed, and thus trying to follow, is different to the actual track of the aircraft and attached leg. Obviously, there will be an element of torsion, but isn't it going to be very secondary to the bending? I imagine you'd need to wind the leg through a good few degrees before you twisted it off. :confused:

28th Feb 2006, 20:08
If it causes two white knuckles then it is torqued;)

28th Feb 2006, 20:10
To me "significant" torque would come from brake application on landing. The resulting forces through the U/C may be bending or otherwise, but it still starts from (significant) torque.

28th Feb 2006, 20:15
.....can you tell the difference between torque and mutter?

28th Feb 2006, 20:19
Yeah b b b but.... the leg's not 'subjected' to torque due to braking action then? :confused:

Actually, I have a better idea. Pub? Pub. :ok:

28th Feb 2006, 20:44
*please see first post*