You are not logged in. ## How to estimate performance Red Admiral

Italian Stallion  Thursday, March 16th 2006, 4:15pm

### How to estimate performance

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Maximum Speed
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Power = Force * Velocity

Drag ~ constant * Velocity^2

Force = mass * acceleration

At maximum speed there is acceleration so sum of forces = 0

Total Force = 0

(Power / Velocity) - (Constant * Velocity^2) = 0

Power / Velocity = Constant * Velocity^2

Power = Constant * Velocity^3

The constant value, k varies from aircraft to aircraft and is a measure of how aerodynamic the airframe is.
Lets take an example.

Supermarine Spitfire Mk IA
Power = 1030hp
Maximum Speed = 571 kph

1030 ^1/3 (cube root) / 571 = 0.01768

Now to find out how fast it goes if we have 1185hp(Mk VC)

(1185 ^ 1/3) / 0.01768 = 598kph

The actual figure for Spitfire Mk VC is 602kph, only slightly different from predicted result.

Spitfire Mk XIV
Power = 2050hp

maximum theoretical speed = 718kph
Actual maximum speed = 721kph.

Its a quick and easy way of calculating maximum speed for different powerplants. Red Admiral

Italian Stallion  Saturday, April 29th 2006, 1:24pm

Cost of US aircraft in WWII

Fiat G50 - 390,000 Lires
Macchi C200 - 400,000 Lires
Reggiane Re2001 - 520,000 Lires
Macchi C202 - 510,000 Lires
SAI 403 (projected) - 96,000 Lires
The prices are not comprehensive of the engine and war equipement, that were properties of the government and were given to the firms, to be mounted on the aircrafts, directly by the administration.
The Lira/USDollar exchange rate was of 19/1 at the end of the '30s.