Spitfire Aileron Bug - Plz check!

[ATAG_Dutch]

@ Bluesman - Because the Spit aileron trim is set on the ground, it's only perfect for a specific flight speed and throttle setting.

A combination of rudder trim and throttle setting will reduce the effect to a minimum, although it shouldn't really be possible to fly the Spit totally 'hands off' for any great length of time.

You'll also notice that in a fast dive, the rudder trim goes way off in the slip indicator, needing a lot of re-trimming on the way down, although I find it easier to just press the pedals.

I certainly wouldn't call this a bug, more of a flight characteristic.

[NZtyphoon]

Spitfire II Pilot's Notes on diving: (http://www.scribd.com/doc/4598146/Pi...lin-XII-Engine)

DIVING
21. The Maximum permissible diving speed is 450 m.p.h. A.S.I.
Note the following:

(iii) The aeroplane should be trimmed in the dive, i.e. the trimming tab control should be set to give no load on the elevator. This will lessen the possibility of excessive "g" being induced in easing out of the dive particularly if the pilot should ease his hold on the stick owing to "blacking out" or any other reasons. No difficulty in easing out of the dive will be experienced even if the aircraft is trimmed in the dive as the elevator control is comparatively light and recovery from the dive is not resisted by excessive stability in pitch. Elevator tabs may be used, very carefully, as in para. 14.

[ATAG_Snapper]

Originally Posted by NZtyphoon

Spitfire II Pilot's Notes on diving: (http://www.scribd.com/doc/4598146/Pi...lin-XII-Engine)

Has anyone been able to dive the Spitfire (any Mark) faster than 420 mph ASI without losing the control surfaces?

[Bluesman]

Thx for replies!

So:

1. The difference between ailerons "on ground" and "in air", the displacement forcing a right roll is normal?

2. Consider rudder trimmed to center side slip, we still expect a little instability (eg. glissade) according to Spitfire flight caracteristics?

PS: We have other aircrafts in CoD that are not affected by this eg. Tiger Moth. In IL2 1946 we dont have this effect too...

Thx,

=AN=Bluesman

[Blackdog_kt]

Originally Posted by Bluesman

Hi friends,

I noticed a bug in Spitfire aileron long time ago and had discussed with pilots from my squadron, all confirmed.

I feel the Spitfire flying with a significant "side slip", even if trimmed it doesnt flight straigh (dont consider wind...).

When we are on land, both ailerons are at neutral positions, but after takeoff the ailerons move a little, rolling do right side.
We can notice that looking to right wing aileron, who will be a "little up".

Tested what this can affect the flight: with fuel cock off and prop pitch set to 0 (no torque) the plane keeps rolling right!

The image below shows the bug.



Please check this and, if comfirmed, let's report this bug to be fixed!

Thx,

=AN=Bluesman

It's not exactly a bug. Many aircraft that didn't have in-flight adjustable trim for all control surfaces were set up this way, either by a built-in trim from the factory or by ground adjustable trims that were set by the ground crews (this is what the 109 rudder was like). One of the Italian birds, i think the MC.202, even had different wing spans to account for this (one of the wings was slightly shorter and this created a rolling tendency that balanced the aircraft out).

The reasoning is that since the plane cannot be trimmed by the pilot in that axis, it should at least be pre-trimmed to make it less tiresome to fly. And this means that they were trimmed for their nominal cruise airspeed, because it was at that speed that the majority of a flight was conducted. So, flying at that speed range requires no pilot input for ailerons, but flying above or below it needs adjustments.

The reason you don't see the surfaces moving on the ground when you are standing still is that trim works aerodynamically: the trim tab needs airflow over the wing to deflect the control surface.

For example, an elevator trim tab is like a small reversed elevator. If you want to dial in some nose up trim, the trim tab moves down. This pushes the rest of the elevator up and makes the nose rise. If the aircraft is standing on the runway however, the trim tab doesn't work much (apart from whatever airflow the propwash generates).