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Why does it turn during take-off?


Pix
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Could anyone help me find out what I am doing wrong? Every time I am about to take-off the aircraft turns left on the runway.

 

It happens in every mission including the Training/Tutorial.

 

I created a new mission with clear weather and no wind. Also with no weapons and ammunition. Just 100% fuel and nothing more. The aircraft is still turning left on the runway.

 

I used the RCtrl+Enter command to check for control inputs. And none of it seems to be affecting the turn. Stick, pedals etc are properly calibrated.

 

Made a 1 min video to show what I am doing. The mission starts from runway with everything preconfigured. No wind etc...

 

 

 

 

The more load I have the more it turns. Basically I have to go zigzag to get the plane up in the air. Feels like I'm missing something important.

 

Any help would be greatly appreciated.

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Yes, rudder inputs. Use your rudder with nose wheel steering turned on until about 60-70 knots then switch it off but just tickle the rudder to keep it straight otherwise you'll over correct it

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Yes, rudder inputs. Use your rudder with nose wheel steering turned on until about 60-70 knots then switch it off but just tickle the rudder to keep it straight otherwise you'll over correct it

 

Thanks. I will try that but I find it hard, I always over correct it. Maybe too high sensitivity on my pedals then.

 

The tutorial says to turn NWS off at 50 knots. Is it wrong?

 

 

Another question: Is there situations where the plane should be trimmed before take-off? If so, how can I know how much to trim it.


Edited by Pix
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While NWS is engaged the steering will be very sensitive, so a very light touch is required. The flight manual says 70. If you disengage too early the rudder will not have enough authority to provide steering.

 

From pg. 486.

During takeoff roll, maintain directional control using nosewheel steering until flight controls become effective. Disengage nosewheel steering at 70 KIAS.

 

Once NWS has been disengaged the pedals will be far less sensitive but you will still be able to steer the aircraft.

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maybe this help:

http://forums.eagle.ru/showpost.php?p=1583020&postcount=20

 

Pay attention to the little dead-zone and and the curve .

This Prevents you to give input when nothing is needed and will help you not to overreact when taxing on the ground.

 

 

Further - Here you find proper tools to examine your inputs :

corrupt calibration? crazy joystick response? Use this tools Fix it


Edited by PeterP

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Experience will teach you what speed to switch the NWS for the conditions and sensitivity of your controller. Being lined up perfectly before you start the high speed roll will minimize the control pressure you need early in the roll. Between 50-70 is normal for most jets. I use 60 myself because many other planes I fly use that speed and by then, I have no use for wheel steering anyway. so, basically as soon as the IAS speed indicator wakes up, I use that as a cue to cycle the steering which hasn't caused me any harm in the 20+ years I've been doing that.

 

If the plane once perfectly aligned while stopped immediately slews off the runway without ANY controller input, then the possibilities are:

1) Stick/rudder is not centered.

2) Trim is not centered.

3) You DO have weather and you just didn't realize it. Call the tower for a winds report.

 

If (as you say) the plane ALWAYS veers off the same direction regardless of what TE/campaign/training you use and ALWAYS the same direction, then this points strongly to #1 or 2.

 

As you guessed, revisiting your controller sensitivity might be in order. Few planes need much wheel control during the early part of the roll.

-Pv-


Edited by -Pv-
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I don't think the offset of the wheel has anything to do with it. The only thing the nose wheel would have to do with it is if its partly turned off centre when you start the roll and as such the slightest left or right bias leads to a big difference at takeoff roll.

 

This is why you steer the wheel at all times. Its not like you can just set it straight and leave it. Its just like a car, if you don't steer the wheel it'll start to drift.

Warning: Nothing I say is automatically correct, even if I think it is.

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I also believe that asymmetrical payloads will make you tend to veer off as well, and most payloads are not perfectly symmetrical if you have a TGP on.

 

X2, asymmetrical loads will pull you off center on takeoff for sure. With no weather and only a TGP loaded the hog has a strong pull to the right on takeoff roll. Also need a couple clicks of trim or a bit of left stick to keep the wings level when you rotate.

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I don't think the offset of the wheel has anything to do with it. The only thing the nose wheel would have to do with it is if its partly turned off centre when you start the roll and as such the slightest left or right bias leads to a big difference at takeoff roll.

 

This is why you steer the wheel at all times. Its not like you can just set it straight and leave it. Its just like a car, if you don't steer the wheel it'll start to drift.

The front wheel is mounted on the right of the centerline, therefore the engines produce more thrust on the left side of the wheel than on the right side, usually pushing the plane to the right hand side.

 

That is at least how I explain for myself - besides the asymmetrical loadout with sidewinders and tgp - why the plane usually wants to turn right when i take off.

 

BUT ... well, the OP speaks about a tendency to the left ... so ... uhm ... dunno! :o)

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Both engines rotate in the same direction.

So at least when you rotate you should see a slights yawing moment.

 

I don't know if the engines are installed 100% on the axis at a-10.

 

On propeller machines they can be installed off axis, to compensate non symmetrical forces at cruise speeds. At all other conditions you have to do some trimming depending on power setting..

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Both engines rotate in the same direction.

So at least when you rotate you should see a slights yawing moment.

 

I don't know if the engines are installed 100% on the axis at a-10.

 

On propeller machines they can be installed off axis, to compensate non symmetrical forces at cruise speeds. At all other conditions you have to do some trimming depending on power setting..

 

Turbine engines don't produce noticeable yawing forces. There is no torque, no P-factor, in the A-10's case, no SSS, no ASS. So really, the engines produce a negligible impact on the yawing moment of the aircraft UNLESS they are not producing the same amount of thrust. An easy way to think about this is:

 

In a propeller aircraft, your engine is driven by a crankshaft which operates by the motion of an engine. As this crankshaft rotates, so does your propeller. This produces torque in the opposite direction of crankshaft rotation. In a turbine, things operate a little bit differently. Hot exhaust gasses are ejected out the rear of the engine, causing the spinning of the turbine, which causes the compressor and fan blades up front to spin. The turbine drive shaft is not mechanically cemented to any other force producing engine. It is free spinning, hence no reactionary movement on the rest of the aircraft.

 

What can happen however, is that one side of the aircraft can be loaded more than the other side. This results in a larger skewed horizontal moment, and more importantly, a larger drag index for that side of the aircraft. That means that one side will accelerate slower (to a degree) than the other side. So in reality, asymmetrical loading DOES produce a yawing moment, but not in the way most people expect.


Edited by Pyroflash

If you aim for the sky, you will never hit the ground.

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Hi,

I do think you are right that there is no noticeable torque, but right now I think there must be some torqe from the jet engine.

Every force createts it's 'counter' force. In the jet engines you have rotor blades and stator vanes.

I think there is a torque from the vanes to the casing to the airframe. But due to its small lever, the force is relative small....

 

This is my current state of mind, maybe I am wrong....

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Hi,

I do think you are right that there is no noticeable torque, but right now I think there must be some torqe from the jet engine.

Every force createts it's 'counter' force. In the jet engines you have rotor blades and stator vanes.

I think there is a torque from the vanes to the casing to the airframe. But due to its small lever, the force is relative small....

 

This is my current state of mind, maybe I am wrong....

 

:book: Hmmmmm! I think this thread is going in the wrong direction. The engines on the A-10c produce 8,900 pounds of static thrust. The engines on a Boeing 707-400 produce over 75,000 pounds of thrust. If engines produced a torque that made an aircraft yaw (for that is what is being suggested) then aircraft like the B747 would have an even bigger tendency to yaw. But this is not what happens - therefore the explanation cannot be right. My feeling is that what is being experienced is due to incorrect trim for take-off and a degree of over-controlling.

 

My experience on the DCS A-10C means that I set up before take-off as follows:

Line up on runway - set 'neutral' trim on the button on the left panel - check the ordinance loaded visually - give a 'blip' left or right on the stick 'coolie hat' to counter any 'visual' drag from the ordinance. Then, advancing the thrust levers to full power as per the manual, use only small amounts of rudder to keep straight (remembering there is a small delay before the effect of any rudder movement). Disengage the NSW early (before 50 knots indicated) because any lack of steering control before the rudders become effective is compensated for by reduced over-controlling by the pilot (me!).

 

This has given me far more stable and controlled take-off runs. When doing formation take-offs I am thus less likely to take out my buddy. He really appreciates this :D

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Thanks for all the replies.

 

So basically the plane is supposed to turn like in the video if you don't keep making minor adjustments for the wheel?

 

I guess I kind of expected it to go straight by it self once it's been lined up. Need more practice with the pedals.

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Thanks for all the replies.

 

So basically the plane is supposed to turn like in the video if you don't keep making minor adjustments for the wheel?

 

I guess I kind of expected it to go straight by it self once it's been lined up. Need more practice with the pedals.

 

 

Don't we all! :D

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So far as I can tell, the only effect an off-center nose wheel has is the turning radius difference, left and right. I don't know if it is in the DCS manual but I do know actual pilots mention this oddity.

The Hornet is best at killing things on the ground. Now, if we could just get a GAU-8 in the nose next to the AN/APG-65, a titanium tub around the pilot, and a couple of J-58 engines in the tail...

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Hi,

I do think you are right that there is no noticeable torque, but right now I think there must be some torqe from the jet engine.

Every force createts it's 'counter' force. In the jet engines you have rotor blades and stator vanes.

I think there is a torque from the vanes to the casing to the airframe. But due to its small lever, the force is relative small....

 

This is my current state of mind, maybe I am wrong....

 

Easiest way to prove this:

 

Take two fans. In one fan, remove the electric motor (you will need to drive a rod through it or something to ensure that it stays on the casing). In the fan with the electric motor still intact, start it up while holding it. You will notice some torque from this. On the fan without the electric motor, simply blow some air through it so that the fan blades move. You will not notice any torque whatsoever, except that caused by friction (note, jet engines have a lot of oil in there to prevent the effects of this friction).

 

Because in a jet engine, nothing cemented to the airframe is driving it, you will see no torque. The "opposite reaction" you speak of isn't that the airplane spins around, but that the burned exhaust gasses slow down due to their impact with the turbine blades. Remember that there is a LOT more going on here than rigid body physics.


Edited by Pyroflash

If you aim for the sky, you will never hit the ground.

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I've had this problem. My aircraft always veers right. One thing i noticed was on night missions, my taxi light looks like its point to the right as well. Which led me to think that its a calibration issue. So i checked the control in the options and rudder is right in the deadzone, which would lead me to think its centered. So essentially I have no idea. Do you guys find your lights to be pointing straight or off center?

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Simple Answer?,

 

The Left Engine Spools Up Quicker than the Right?

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