Tail Coming up at ~70 km/h on Takeoff

Excellent notes rel4y !

I may have found something a few days ago that could possibly be related to the whole trim discussion. In construction documents I saw that the wings chord line is angled 1°42' (1.7°) upwards in comparison to the fuselage main axis (109 G-10). To that the wing beam is angled forward by the same amount so it is again orthogonal to the fuselage main axis. The motor (part# 8-209.710) is angled 88°58'14'' to the Rumpfstirnwand which is often falsely called firewall. That translates to an upward angle of ~ 1.03° to the fuselage main axis. I looked this up after the MK 108 discussion, which has an initial elevation of -0.069 in DCS, which is downwards if I interpret correctly.

 

So the engine is angled about 1° upwards compared to the fuselage main axis but about 0.67° downwards to the wing chord line.

 

The 109 F apparently has an motor angle of 43' (0.7167°) to the fuselage main axis and ~ 1° to the wing chord line.

 

Do you have the same data Yo-Yo?

I am reading many accounts and watching videos of restored Bf-109s during takeoff. A very common notation is that one should delay allowing the tail to rise before rudder becomes effective (60-70 km/h) and that it easily rises at this point.

 

But in DCS module I cannot get such tail rising behavior during the takeoff run. Even with full forward controls the tail is not rising smoothly, easily, or naturally until much faster (~140 km/h).

 

How can I raise the tail smoothly in this airplane to see over the nose at < 100 km/h?

Set prop governor to manual---prop pitch at 11:30 o'clock on the dial, take 500 Kg bomb, -2 elevator trim, no flaps, 65% fuel load, nice and easy with the throttle---no bursts >>> tail comes up nice and easy just under 200 kph . Don't need full throttle for take-off. On take-off roll I watch my front side windows with the runway sides being equal. Full right rudder at start of take-off, then play with rudder pedals as speed increases.

In air at take-off: Immediately set prop governor to automatic, gear up, outer lights off, adjust elevator trim as necessary.

Options / Special = Aileron Trim +2 ; Rudder Trim -20 ; Take-off Assistance 0

No bomb >>> I set elevator trim to zero

That's how I do it. (Took me a long time to figure out my setup.)

-+-

Hitting ground targets? No problem

Dogfighting? I still suck

Landing? Getting better at it, still mess up once in awhile (190 is more difficult successfully landing)

Set prop governor to manual---prop pitch at 11:30 o'clock on the dial, take 500 Kg bomb, -2 elevator trim, no flaps, 65% fuel load, nice and easy with the throttle---no bursts >>> tail comes up nice and easy just under 200 kph . Don't need full throttle for take-off. On take-off roll I watch my front side windows with the runway sides being equal. Full right rudder at start of take-off, then play with rudder pedals as speed increases.

 

In air at take-off: Immediately set prop governor to automatic, gear up, outer lights off, adjust elevator trim as necessary.

 

Options / Special = Aileron Trim +2 ; Rudder Trim -20 ; Take-off Assistance 0

 

No bomb >>> I set elevator trim to zero

 

That's how I do it. (Took me a long time to figure out my setup.)

 

-+-

 

Hitting ground targets? No problem

 

Dogfighting? I still suck

 

Landing? Getting better at it, still mess up once in awhile (190 is more difficult successfully landing)

Useful experience!

As a DCS Jet pilot transitioning to WW2 Props ready for Normandy, any tips are useful.

Taking off is my problem! Landing is fine!

I can say, from my experience, that DCS has nailed some of the complex forces at work here. I must quote the CFI Instructor here and concur that I am feeling these effects.

"When you raise the tail, you are effectively rotating the prop disc (the plane in which the propeller rotates) so that the lower half of the disc moves backward, and the upper half moves forward. The laws of “gyroscopic precession” rule that a rotating mass (i.e. the prop disc), when displaced in such a fashion will displace or “precess” that moment through 90 degrees in the direction of rotation. If you can’t dig that, put more simply it means that in the case of a propeller turning clockwise when viewed from the cockpit, raising the tail and therefore forcing the prop disc into a new plane, will have the effect of the same prop disc trying very hard to twist through 90 degrees. The result is a very strong force which will yaw the aircraft to the left. It doesn’t matter if you don’t understand this, you just need to know it happens. "

The only way for me, is at Max combat weight (no bomb), I open throttle smoothly to full, dance on the rudders like a maniac on hot coals, when the tail comes up, forward stick keeping main gear down until she tells me she wants to fly straight, then gear up, (never tried flaps) and get as fast as possible in the shortest time.:joystick:

Bravo DCS, these warbirds are a helluva handful!:D

Cheers

David

Useful experience!

 

As a DCS Jet pilot transitioning to WW2 Props ready for Normandy, any tips are useful.

 

Taking off is my problem! Landing is fine!

 

I can say, from my experience, that DCS has nailed some of the complex forces at work here. I must quote the CFI Instructor here and concur that I am feeling these effects.

 

"When you raise the tail, you are effectively rotating the prop disc (the plane in which the propeller rotates) so that the lower half of the disc moves backward, and the upper half moves forward. The laws of “gyroscopic precession” rule that a rotating mass (i.e. the prop disc), when displaced in such a fashion will displace or “precess” that moment through 90 degrees in the direction of rotation. If you can’t dig that, put more simply it means that in the case of a propeller turning clockwise when viewed from the cockpit, raising the tail and therefore forcing the prop disc into a new plane, will have the effect of the same prop disc trying very hard to twist through 90 degrees. The result is a very strong force which will yaw the aircraft to the left. It doesn’t matter if you don’t understand this, you just need to know it happens. "

 

The only way for me, is at Max combat weight (no bomb), I open throttle smoothly to full, dance on the rudders like a maniac on hot coals, when the tail comes up, forward stick keeping main gear down until she tells me she wants to fly straight, then gear up, (never tried flaps) and get as fast as possible in the shortest time.:joystick:

 

Bravo DCS, these warbirds are a helluva handful!:D

 

Cheers

 

David

Hmm...I can only tell you how I TO with the plane:

1. Trim full nose heavy, apply full brakes, elevator, right rudder and aileron.

2. Increase throttle gradually until you reach 1.2-1.3 ATA.

3. Disengage brakes, pick up speed. Put ailerons in neutral the moment you feel the plane is starting to slip right. You may have to apply very slight brake to keep the plane straight before the rudder becomes effective.

4. Ease pressure on the elevator until the stick is neutral or the tail has come up. Continue using rudder to keep the plane straight if needed.

5. Pull back on the elevator to lift off.

Allow me: ( helps a lot, although not mandatory... )

0. Tailwheel Locked.

Hmm...I can only tell you how I TO with the plane:

 

1. Trim full nose heavy, apply full brakes, elevator, right rudder and aileron.

 

2. Increase throttle gradually until you reach 1.2-1.3 ATA.

 

3. Disengage brakes, pick up speed. Put ailerons in neutral the moment you feel the plane is starting to slip right. You may have to apply very slight brake to keep the plane straight before the rudder becomes effective.

 

4. Ease pressure on the elevator until the stick is neutral or the tail has come up. Continue using rudder to keep the plane straight if needed.

 

5. Pull back on the elevator to lift off.

Allow me: ( helps a lot, although not mandatory... )

 

0. Tailwheel Locked.

Well yeah. :P

That's kind of THE prerequisite. Don't want to Spitfire out of control. :P

Although I msut confess 80% of the time I takeoff with thetailwheel unlocked.

We just have to use a bit of differential braking during the initial takeoff run, when the rudder authority isn't yet available to correct any "escape" tendencies :-)

Hmm...I can only tell you how I TO with the plane:

1. Trim full nose heavy, apply full brakes, elevator, right rudder and aileron.

2. Increase throttle gradually until you reach 1.2-1.3 ATA.

3. Disengage brakes, pick up speed. Put ailerons in neutral the moment you feel the plane is starting to slip right. You may have to apply very slight brake to keep the plane straight before the rudder becomes effective.

4. Ease pressure on the elevator until the stick is neutral or the tail has come up. Continue using rudder to keep the plane straight if needed.

5. Pull back on the elevator to lift off.

This, I subscribe. But I don't even use the elevator to lift off. The K kindof flies herself from there.

I just posted a video about it.

I almost gave up on the use of the rudder. But then I noticed that the rudder becomes effective at a certain airspeed. The K has a small tail fin and rudder, it needs a lot of air to feed it properly.

Cheers,

Well yeah. :P

 

That's kind of THE prerequisite. Don't want to Spitfire out of control. :P

Don't think I mentioned it, yes, tail-wheel locked takeoff and landing.

Somebody mentioned the physics that is going on. Much appreciated the description.

If done correctly, landing can be achieved on 3-wheel touchdown and perfect roll-out.

Btw, you can also land it absolutely fine with 2-wheel touchdown.. at least in DCS.