Spitfire Mk.I strange behaviour

[gimpy117]

Aerodynamically that makes no sense...weight has an effect on drag from the wings. Heavier planes should be slightly slower

[Kurfürst]

Weight has very marginal effect on top speed. See for example this German graph for 109G speed decrease at various weights: http://www.kurfurst.org/Performance_...fect_speed.jpg

The story short: the graph says that if you increase the 109G weight from 3000 kg massively, to 4000 kg, speed will decrease by about 7 km/h at SL and by about 18 km/h at rated altitude.

As more practical or realistic weight changes, ie. 1-200 kg (plane carried 300 kg fuel), the speed difference is only 1-2 km/h...

[Flanker35M]

S!

But the thing is that on Bf109E the difference between empty and full is next to nothing, within 2-3km/h. On Spitfire the difference is over 10mph so a lot more. And the heavier beng faster. Strange behaviour in the game. Need more testing.

[taildraggernut]

This might not be a bug, it is possible that if a higher fuel load results in the C o fG moving back then this would have a beneficial effect, a C of G which is further back needs forward elevator to maintain level, the side effect of this is to get some extra speed in level flight through a reduction in drag caused by the elevator, this is an effect some modern passenger jets use where they deliberately pump fuel to tanks at the rear (in the tailpane itself) for that very reason. concorde is a famous example of a 'fuel trimming system' but for slightly different reasons.

Note: I say 'might'.....I have no idea of spitfire load and balance.

[TomcatViP]

Originally Posted by taildraggernut

This might not be a bug, it is possible that if a higher fuel load results in the C o fG moving back then this would have a beneficial effect, a C of G which is further back needs forward elevator to maintain level, the side effect of this is to get some extra speed in level flight through a reduction in drag caused by the elevator, this is an effect some modern passenger jets use where they deliberately pump fuel to tanks at the rear (in the tailpane itself) for that very reason. concorde is a famous example of a 'fuel trimming system' but for slightly different reasons.

Note: I say 'might'.....I have no idea of spitfire load and balance.

I am with you on this.

The fuel tank is also closest to the CG on the 109.

[Ernst]

Interesting. A WW2 nightfighter ace, Martin Drewes, used to remove the camouflage of his 110 and was capable to fly some km/h faster.

[gelbevierzehn]

Originally Posted by Ernst

Interesting. A WW2 nightfighter ace, Martin Drewes, used to remove the camouflage of his 110 and was capable to fly some km/h faster.

That was not the weight effect, it was a perfect filled and polished finish of the outer skin to reduce drag...