The exact impact of clipped wing tips on Spitfire IX performance

[klebor]

I noticed there is no information about impact of clipped wings on Spitfire IX performance in "settings" menu and aircraft specification in pre-flight menu.

Do someone have some details?

[303_Bies]

In an AFDU trial at RAF Duxford between a clipped-wing Spitfire and a standard Spitfire Mk Vb:

Air Fighting Development Unit at Duxford

Clipped-wing (32ft 6ins) Spitfire versus standard wing (36ft 10ins) Spitfire

The following information comes from flight trial held late in 1942.

Method of test

Two Spitfire Mk Vb aircraft were selected with as near-identical performance as could be managed, the loading and equipment carried were standard in each and the propeller, engine and finish of each aircraft were similar.

A test flight was made under maximum cruising conditions and no differences could be determined. The wing tips were then removed from one aircraft and trials were carried out, each trial being performed twice to enable the pilots to be changed. The wing tips were then replaced and removed on the other aircraft and the tests repeated.

Differences in speed were taken as relative increases or decreases owing to possible instrument inaccuracies, and position error differences with and without tips.

Readings for level speeds were taken at 10,000, 15,000, 20,000 and 25,000ft, zoom climbs were made 10,000 - 15,000ft and 20,000 - 25,000ft and dives were made with similar engine settings.

Results of Comparative Tests

Level Speed

• 10,000ft: In each case the clipped-wing Spitfire proved the faster by a small margin of about 5 mph.
• 15,000 and 20,000ft: The average results at these two heights showed that the difference in speed is not measurable.
• 25,000ft: The standard Spitfire is very slightly faster than the clipped-wing Spitfire.

In all level speed runs the clipped-wing Spitfire accelerated faster than the standard Spitfire.

Climb

The average difference in time during zoom climbs from 20,000 to 25,000ft was 15 seconds in favour of the standard Spitfire.

From 10,000ft to 15,000ft no differences were indicated.

Dive

In all diving tests the clipped-wing Spitfire drew away from the standard Spitfire.

Manoeuverability

At all heights to 25,000ft the rate of roll is considered improved by the removal of the wing tips.

Roll rate for a standard Spitfire was 105 degrees per second at 200mph. This was increased for the clipped-wing version to 175 degrees per second at the same speed. It should be noted that the clipped-wing version suffered the same difficulties in the rolling plane as the standard fighter as the speed of the aircraft increased.

The response to aileron movements is very quick and very crisp. Four dogfights were carried out, starting with the standard Spitfire on the tail of the clipped-wing Spitfire. On two occasions the clipped-wing Spitfire evaded so rapidly in the rolling plane that it was able to lose the standard Spitfire and reverse the positions in about 20 seconds. On the third occasion the clipped-wing Spitfire was also able to lose the standard Spitfire. The fourth occasion was at 25,000ft and the standard Spitfire was able to keep the clipped-wing Spitfire in sight.

The minimum turning circle of the clipped-wing Spitfire at 20,000ft has been increased by 55ft at 1,025ft compared with the Fw190 turning circle of 1,450ft (RAE Farnborough figures). This slight increase does not therefore detract from the fighting qualities of the aeroplane in any way, since the clipped-wing version is unlikely to be in combat with the standard Spitfire.

Take-off

No difference was detected.

Landing

No difference was detected.

General

The view downwards over the reduced wing tips is improved considerably. The strengthening of the wing by removal of the wing tips may permit higher maximum IAS to be used.

Edited May 25, 2018 by bies

[-TBC-AeroAce]

It will increase lift induced drag, decrease turning ability but increase roll rate.

[unreasonable]

Also seems to have an effect on behaviour when inverted, see other thread.

[ShamrockOneFive]

It feels faster in roll rate right now but not substantially so from a "feel" point of view. Will have to run some tests to measure it.