Spitfire Ia100oct [max speed at 15000ft]

[UFO_113]

Spitfire Ia100oct [max speed at 15000ft]

no matter how perfect i trim and level the plane, at 15000ft the most i can get and sustain is 260mph; from 2600-2800-3000rpm +boost sustained flight, with 40% radiator

that's the display on the speed meter anyway; is this to be expected, or am i doing something wrong?

i'd really appreciate some input from anyone,

cheers,

[RAF74_Buzzsaw]

WWII Aircraft speedometers were simple pressure measuring devices.

The speedometer displays Indicated Airspeed. (IAS) This does not take into account the effects of the thinning atmosphere at higher altitudes.

True Airspeed, (TAS) must be calculated.

Please see this page for a simple explanation:

https://en.wikipedia.org/wiki/True_airspeed

In addition, the speedometers in the game aircraft are not 100% accurate for even IAS.

To get correct IAS, you need to go to the no cockpit view and read off the instruments shown there.

260 mph IAS at 15,000 ft is approximately 340 mph TAS.

[UFO_113]

ok then,, i actually knew about IAS and TAS some time ago, but wasn't making the relation at this time;

the 340 mph TAS value is in line with what i was expecting,
i only get 260 mph IAS if i outstretch it with 3000 rpm +boost, which can only be sustained over very short period,
250 mph IAS is the more realistic profile, that is 2750/2800 rpm +boost 40% rad,

that should lead to:

Maximum cruising speed (at 15,000 ft.) : 318 mph
http://www.spitfireperformance.com/spitfire-I.html

i'm unrusting my skills these days, thx for the excellent reply

[VO101_Mate]

Hi,

If you need a quick rule of thumb for TAS:

4x of a thousandth of your altitude in ft. And add it to your IAS.

For example: 260 kias at 15000 ft
4x15+260kias= 320tas

Cheers

[Alejo68]

Hi,

If you need a quick rule of thumb for TAS:

4x of a thousandth of your altitude in ft. And add it to your IAS.

For example: 260 kias at 15000 ft
4x15+260kias= 320tas

Cheers

I needed a rule like this... Ty