Another hornets nest

[Oldman731]

Originally posted by Seeker
Lancaster pilots had to use full right rudder on an overloaded takeoff to counter torque.

That's got four engines...

B-24 was famous for requiring a lot of right alieron.  There's a cartoon somewhere showing a B-24 pilot with huge biceps - on his left arm only.

- oldman

[214thCavalier]

The B24 pilots had to hold the yoke with their left arm whilst working throttles etc with their right.
It was known as a heavy aircraft to fly (no power assistance) and required constant trim adjustments.
Therefore the inflated left bicep was due to the left arm doing a lot of work just to fly the plane.

Pilot Comments:

"You could always tell a Liberator pilot by the bulging biceps muscle in his left arm, from hauling on that yoke for 14 hours at a stretch."

"Where the B-17 was an airplane, the B-24 was a truck."

"The airplane has inherent directional stability which may be maintained for long periods of time by slight adjustments in trim.  However, the controls are normally heavy, as they should be in a heavy airplane, and the pilot who fails to maintain proper trim is in for an exhausting workout." (From the B-24 Training Manual)

TAKEOFF

    * Cowl Flaps: 1/3 Open
    * Flaps: 1/4 (10 degrees) down
    * Mixture:   Aircraft equipped with auto-mixture control.  Set to full rich.
    * Elevator trim: +1-2 degrees (nose-up)
    * Rudder trim: +2-3 degrees (right)
    * Aileron trim: Neutral
    * Power: 49" Hg/2700 rpm
    * Liftoff speed: 120-130 mph IAS

Apply power smoothly and gradually, walking the throttles forward evenly until reaching full takeoff power in the first 1/3 of the runway.  The aircraft will have a moderate tendency to pull to the left; use right rudder or differential throttle to correct.  Good rudder control is achieved by 80 mph IAS.  At 90 mph IAS, pull back on the yoke to lighten the nosewheel and assist in raising the nose.  Hold the nose up and allow the aircraft to fly itself off the runway at about 120-130 mph, depending on gross weight.  Retract gear as soon as a positive rate of climb is established. After reaching 140 mph IAS reduce power to rated power (46" Hg and 2550 rpm).  Retract flaps before reaching 150 mph IAS.  Hold the aircraft in a very shallow climb until an indicated airspeed of 155 mph is achieved.

Taken from http://www.shockwaveproductions.com/wingsofpower/manual/b24.htm

[Straiga]

Great post 214th Cavalier Thanks

I have time in a b-17G sounds like what how the 17 was on takeoff and real heavy on controls too. Trim baby!

HMM but no aileron for prop torque and no aileron trim for takeoff especialy in a heavy airplane like this, interesting. It may be I might know something.

I was just wandering why in AHII the B-24 rolls right aileron in on auto takeoff and has right aileron in cruise flight. But I dont see any major rudder input either. In auto takeoff it should reflect the same control inputs as you decribed.

Seems like all the planes in auto takeoff are the same way. I know when flying any single fighter that when you look back in a climb the rudder should be deflected right quite a bit but its is just centered. I just dont understand. In the real plane its definatly way to the right. You have to hold rudder for P-factor and slip stream to point the nose.

Straiga

[GScholz]

Straiga, instead of looking at the control surfaces look at the trim gauges. Auto-pilot in AH only control trim AFAIK

[Straiga]

I know but when you look at the surfaces they dont reflect needing rudder in the climb, its 0. At least some rudder should be used right. When you trim the controls it should be deflected. The trim tab goes one way while the control surface is deflected in the oposit direction.

Heres what it should be for a P-51 on takeoff. Power increases as right rudder is applied and should show about 6 degrees right rudder trim too. Elevator full up and elevator trim 2 degrees up. No aileron or aileron trim, it should be 0 anyway. Release some elevator to let the tail fly. Get the plane flying and set power for climb. You still need right rudder and very little elevator set the trim and no aileron for a straight out climb. Im still trying to figure what AHII is doing but its not this.

Straiga

[hitech]

Straiga: How about you first explain how torque is removed just by moving engnines out on the wing.

[Guppy35]

Originally posted by Oldman731
B-24 was famous for requiring a lot of right alieron.  There's a cartoon somewhere showing a B-24 pilot with huge biceps - on his left arm only.

- oldman

Always keep me working oldman

Dan/Slack
note bottom left

[joeblogs]

I may be recalling this wrong, but it is my impression that all four engines on this plane rotated in the SAME direction. Why it was designed that way is beyond me.

-Blogs

Originally posted by Straiga
OOOHHH TESTY!

Yes your right I have never had an AHII physics class Im not into fiction.

Im in a physics class every day flying for a living.

So explain why right aileron is used on take off in a four engine bomber when you dont need to. Explain youself I would like to hear this.

I guess you dont have a multi-engine rating either.

Straiga

[Straiga]

Cuppy35 I dont see were its says he has a big arm due to ailerons on takeoff. YOU DO NOT NEED AILERON ON TAKE IN A  B-24, B-17, and AVRO LANCASTER, B-26, B-29. But rudder you need alot. If anybody tells you different they dont know what there talking about, period.

Torque in these four engine bombers produce a yaw torque not a roll torque. Torque is there but not in a roll moment, to need aileron use for takeoff or in cruise flight. If you had some flight experience of any kind in a multi-engine you would agree.

These are some of the multi's I have flown C-310, Piper Seminole BE-55 TC, C-421, C-414,E-90, B-200, B-300,B-350, DHC-6-300, DHC-8, DHC -7 this is a big four engine turbo prop, B-17G, L-1011, DC-9-50, B-717, DC-10-10 &-30, B-767-300ER. None of these require any kind of airleon or trim on takeoff. WHAT MULTI'S HAVE YOU FLOWN?

Read what 214thCaviliar wrote about takeoff from a pilot describing a takeoff. Hmm no aileron and no aileron trim.
When are you going to believe it. I guess never. Thats sad

I have B-17G time, its funny that I have flown a four engine bomber but someone who has not , knows more about flying the thing than I do.  No experience and no clue. So whats it take to believe in something and admit your wrong. I guess when it hit between your eyes or maybe not.

So how much four engine bomber time do you have, or do you even have a basic multi-engine liscence. Like I said no experience.

Straiga

[GScholz]

I don't think turbo-props and jets produce torque.

[Straiga]

Turbo props due to the prop torque itself, and turbines will if the N1 and N2 stages turn in the same direction. Some N1 and N2 stages are counter rotating.

Straiga

[Golfer]

Granted it's 1:15am now but I have been reading and rereading straigas posts and can't find where he said moving the engines outboard on a wing removes torque.  Or at least didn't interpret the info that way.

I know if you move the engines outboard on the wings, you've got a bigger arm between that engine and the CG so if you lose an engine the other one has just that much more leverage to upend the airplane on a twin (Vmc).

I too have noticed the B-24 likes to torque left (much like a single would, if rudders were left unattended) on takeoff.  It doesn't have counter-rotating propellers so P-factor/Torque/natural left turning tendencies could have to do with this.  Multiply by 4 and I see how this could be a fairly big issue.  In other airplanes, smooth application of power yields no real turning tendencies one way or the other.  I don't normally think much about the 24's little wobble, but this week I've found myself taking off of small airfields loaded with bombs and a mountain on either side of the runway.  Made me really pay attention to technique so I didn't wind up decorating the hillsides with virtual airplane parts.

My only explanation for the phenomenon would be the natural left turning tendencies associated with a clockwise rotating engine times four.

[Straiga]

When you take four engines and mount them on the wing you do not cancel torque from the engines or the props you just transform it into a yaw torque moment. Be it four times more than a single fighter would be, they are mounted to a much bigger airplane.
There is now more mass to move, and know there is a longer arm distance from the engines datum to the logitudinal center of the gravity. The natural twisting moment of prop or the engine torque on the airframe, like in a single engine fighter, is not the same for a four engine airplane. Because of the larger arm the engines cant not roll the airframe.
But as torque is trying to force a roll moment which it cant, it transfers it into a yawing moment torque to the left. So the yaw is the only force thats going to effect the airplane at this time on takeoff and a large amount of rudder is needed for directional control. Now as we rotate the airplane we now get two other forces that come into play.

Gyro procession will affect the plane to the right because of the pitch up moment or raising the nose gear off the ground, and the resultent moment acts 90 degrees later in the prop rotation and the force pulls the plane to the right.

P-factor the downward right rotating prop has a higher angle of attack to the relative wind, then the oposit upward rotating prop. This yaws the airplane to the left as turning force.

When you lose two engines on the same side, say the left side engines 1 & 2 then this makes the 3 & 4 engines the critical engines. Meaning that the P-factor on the 3 & 4 engines have a larger arm away from logitudinal center line. With the 1 & 2 engines feathered the drag from dead engines pull the plane to the left. The two good engines are pushing the nose to the left in a yaw torque moment.

But if the 1 & 2 engines were the ones that were running the yaw moment from the p-factor would not be as great or less critical being closer to the Logitudinal center of gravity.

We add right rudder to prevent this yawing moment. We call this dead foot dead engine, or good foot, good engine, this is a good clue to tell during the engine failure which engine or engines have failed due to yaw and rudder application. We also verify, identify and feather the dead engines and  do a clean up after airplane is under control.

Just because we have right rudder in the plane it still does not want to fly straight or cordinated. In training we tape a string to the windscreen and when this string is straight on the windscreen you are flying straight. But we also have to roll the left wing 5 degrees into the good engines to help keep the plane straight, and to help counter the yawing moment.

When you fly a multi-engine the worst thing you can do is get the plane slow below effect flight control airspeed. We call this VMCA (minimum controlable airspeed)this is the minimum airspeed at which you will lose directional control of the airplane. Not enough airspeed across the flight controls to counter the force on the airplane. If you were to go below VMCA with the 3 & 4 engines yawing to the left with no aileron, elevator or rudder, effectiveness, the airplane will drop the left wing and the yawing moment will increase and will continue to drop the left wing. Then the airplane will roll inverted and be uncontrolable.

To get out of this situation, if you had the altitude, is to pull off the power on the running engines, point the nose down and level the wings. While increaseing the airspeed above VMCA and then slowly reintroduce power and maintain blue line (VYSE) or (VYME) best single or multi-engine rate of climb speed. Then hope you can get it home.


Straiga

[GScholz]

Originally posted by Straiga
Turbo props due to the prop torque itself, and turbines will if the N1 and N2 stages turn in the same direction. Some N1 and N2 stages are counter rotating.

Straiga

Really? How do these fans and props generate torque on the airframe when they are not mechanically connected to it? The expanding air deflects the fan blades in one clock direction while it self being deflected in the other. The structure should be unaffected. Almost like having a prop driven by a windmill.

[joeblogs]

The B-24 Pilot's training manual (1945) indicates that all 4 propellers rotate in the same direction.

Manual recommends rudder & elevator trim for takeoff.

-Blogs

Originally posted by joeblogs
I may be recalling this wrong, but it is my impression that all four engines on this plane rotated in the SAME direction. Why it was designed that way is beyond me.

-Blogs