Mustang crosswind take off

[miaig]

Hi,

How do you take off in a P51 with crosswind on simulation mode? I went through training and then I started the campaign. I noticed that taking off in the campaign mission is much harder than it is during training, even though I did both on sim. After a few tries I managed to take off (no crosswind) but then, at the next mission where there is a 10m/s crosswind I got stuck. I tried all kinds of things: setting different trims for rudder and ailerons, using the throttle very slowly or faster than usual. I tried using an outside camera to better see when the plane starts going left or right.

The result was always the same, as soon as a certain speed is reached, the aircraft is steering rapidly and goes off the the runaway. It mostly goes to the right, but sometimes to the left too. When this happens it can not be controlled anymore, applying opposite rudder just flips the plane but the direction mostly stays the same (about 45 degrees off the runway). I think this sudden change of direction happens when the tail lifts but I am not 100% sure and there isn't anything I can do about it anyway because I keep the stick back all this time so basically the tail lifts by itself.

Thanks.

[NineLine]

Are you using any flap on take off?

[miaig]

Are you using any flap on take off?

 

I tried with flaps on and without but I can't see any difference. I tried this mission more than 50 times while trying all kinds of things but nothing seemed to make a major difference. The only thing that does is how slowly I start rolling, but then again, at a certain speed I can not control it anymore.

[NineLine]

If you can, save a track and share it here, maybe someone can see where you might be going wrong.

[miaig]

If you can, save a track and share it here, maybe someone can see where you might be going wrong.

 

Ok, I'll do that tonight, thanks. I have a few questions though:

- should the rudder still be trimmed to 5 degrees?

- should I keep the stick all the way back or just a bit?

- should I start rolling gently or should I get the manifold pressure up to 30 and then release the brakes as in the tutorial?

[NineLine]

I always trim 5 degrees, I generally start with the stick full back and slowly let it out, and as well I build up a little bit of pressure before releasing the breaks...

[159th_Viper]

No rudder trim in such a crosswind (you'll get sodomised) and no flaps. Slowly run the MP up to 42. Stick full aft and then release when you start rolling. Do the rudder dance when adequate speed is achieved for rudder authority and you'll lift off no issue.

[NineLine]

[miaig]

Slowly run the MP up to 42.

 

Should I go to 42 and then release the brakes or I shouldn't touch the breaks at all? I assume that keeping the brakes on (like in the tutorial) just makes the run shorter but at the expense of making the airplane harder to control. Is that correct?

[159th_Viper]

Don't touch the brakes at all - gives you opportunity to gauge what the cross-wind is doing to the plane so you can anticipate timorously.

[miaig]

I generally start with the stick full back and slowly let it out

 

I realized that's one thing I didn't do, I always keep the stick full back, I never let it go. Hmm....

[NineLine]

I realized that's one thing I didn't do, I always keep the stick full back, I never let it go. Hmm....

 

That was a bad habit I got from IL2:CloD where you could get away with that, DCS isnt so forgiving.

[159th_Viper]

Here's a quick and dirty track with a 10m/s (left-to-right crosswind) takeoff from Batumi. Forgive the somewhat untidy flight as I have literally not flown the Mustang in eons........

 

In any event, bring up the control indicator (RCtrl Enter) to see what I am doing with the rudder and aileron at the different flight regimes/transitions. If it does not play back correctly let me know and I'll Youtube it.

 

Track: Mustang Crosswind 10ms take-off.trk

Edited March 28, 2014 by 159th_Viper

[miaig]

Here's a quick and dirty track with a 10m/s (left-to-right crosswind) takeoff from Batumi.

 

Great, thank you, I'll take a look tonight.

[miaig]

I've tried some more, still no luck. I am attaching a trk file that shows what happens. The airplane starts going right and no amount of rudder is bringing it back. :helpsmilie:

take-off-fail.trk

[159th_Viper]

I've tried some more, still no luck. I am attaching a trk file that shows what happens. The airplane starts going right and no amount of rudder is bringing it back. :helpsmilie:

 

My take:

 

1 - You did not lock your tailwheel.

 

2 - Another thing, at that speed you start veering you have no rudder authority - all you are doing is steering, explaining why your rudder input is ineffective.

 

I'll see if I have a quick second to revisit and post a takeoff track of that specific mission.

[miaig]

1 - You did not lock your tailwheel.

Wait, isn't the tailwheel locked when the stick is vertical? I thought it's unlocked only when it is brought forward.

 

2 - Another thing, at that speed you start veering you have no rudder authority - all you are doing is steering, explaining why your rudder input is ineffective.

I don't think I understand this. If the rudder is ineffective, how should I correct the direction then?

 

Sorry for the noob questions.

[159th_Viper]

Wait, isn't the tailwheel locked when the stick is vertical? I thought it's unlocked only when it is brought forward.

 

No.

 

As I said in one of my first posts, pull stick straight back to lock and then leave stick at neutral for take-off run.

 

 

I don't think I understand this. If the rudder is ineffective, how should I correct the direction then?

 

Steering authority is enough to keep you on track until sufficient speed is obtained for rudder authority. The difficult part is anticipating what your plane is going to do and providing input to counter the inevitable directional changes in the cross-wind takeoff. Hopefully a SME will wander past this post and explain why things are happening as they are - I know but cannot explain, if that makes sense at all - it's all way too technical for my well-aged cerebrum :)

 

 

Sorry for the noob questions.

 

NEVER apologise for asking sensible, reasonable questions - You'll always be welcome to do so :)

[sobek]

No.

 

As I said in one of my first posts, pull stick straight back to lock and then leave stick at neutral for take-off run.

 

I disagree. It is locked, unless the tailwheel is not aligned with the rudder (if previously unlocked), it swivels freely until it is aligned with the rudder, at which point it will lock when the stick is neutral or aft thereof.

Edited March 29, 2014 by sobek

[159th_Viper]

I disagree.

 

Watch his track, take control and see for yourself.

[sobek]

Watch his track, take control and see for yourself.

 

Doesn't matter, the tailwheel is locked or will lock while the stick is in neutral or aft thereof. You do not need to pull it back for the tailwheel to lock. The only exception i can think of is if you have skewed neutral excessively by using insane amounts of nose down trim.

[effte]

And even then, trim won't start pushing the stick forward until you gain a bit of speed, at which point the rudder should start to give you a bit of aerodynamic control anyway.

[159th_Viper]

@ miaig

 

Here's another track captured with that specific mission:

 

Mustang Crosswind 10ms take-off Take2.trk

 

Again, very messy but illustrates inputs needed to get her off the ground. Best advice would probably be to practice normal take-offs until you are comfortable. Then start with 2m/s crosswind and practice that. Slowly increase winds by 1m/s and practice, practice and more practice - you'll get it eventually - all it takes is time :)

[miaig]

Best advice would probably be to practice normal take-offs until you are comfortable. Then start with 2m/s crosswind and practice that. Slowly increase winds by 1m/s and practice, practice and more practice - you'll get it eventually - all it takes is time :)

That's what I basically did. I realized I'm not very good at taking off even without a crosswind so I practiced that for a while and then tried again and I managed to take off with the crosswind once. I kept the stick a bit back and to the right and I lifted the tail completely when the plane started swerving right (the rudder was not very effective at that moment). When the tail was up in the air the airplane was going relatively straight and taking off wasn't difficult at that point.

Thanks for all the help and speaking of messy you should see my take off. It would be comical if it wasn't the result of more than 100 failed tries :D

p51-3- takeoff-crosswind..trk

[HotTom]

I haven't watched your tracks (not willing to invest that much time, sorry:() but here are some thoughts:

 

*You don't mention the wind direction. Are you aware that the nose of the plane will turn INTO the wind in a cross wind because the lighter tail with that big fin is being weathervaned or pushed away from the wind? That's kind of a crucial concept.

 

*As to using the 5 degree rudder trim, I don't use it with a crosswind because it just adds another factor I have to consider but your mileage may very.

 

*The manual (P. 130) advises (in a cross wind) keeping the tail down ("keep the aircraft firmly on the runway") until you reach takeoff speed. In a normal takeoff I gradually release pressure on the stick (and thus the tailwheel) as I gain speed. With a cross wind, keep the stick fully back as long as I can and only start easing up on it after I am well over 100 mph. That means a longer takeoff run but there's always plenty of runway. It's not always pretty but it usually works.

 

*The manual also suggests (correctly) that you crab into the wind as soon as you are airborne. Again, you need to know the wind direction relative to your aircraft so you can turn into it (remember the nose already wants to go that way -- into the wind -- because the tail is being pushed in the opposite direction). I always scribble the wind direction and speed (1 m/s equates to about 2 mph) down during the briefing and look at my compass to see where it it coming from relative to my path on the runway. A quick diagram on scarp paper also helps.

 

You can use "Create Fast Mission" to practice (I do, I fly only against vehicle targets) and select clear skies (0 cross wind), Cloudy (1 m/s from 160 degrees), Precip (5 m/s from 24 degrees) or Stormy (9 m/s from 248 degrees). Remember the wind direction is true, not relative to your airplane. You have to look at your compass to figure where it is coming from relative to your plane on the runway).

 

Hope that helps. RTFM. :book:

 

:pilotfly:

 

HT

Edited April 15, 2014 by HotTom