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View Full Version : Tempest 9lbs top speed at 4000ft wrong?



FA_Whisky
10-17-2007, 11:10 AM
Look at this:
http://www.spitfireperformance.com/tempest/temptest.html
And compare that to the data from Il2 compare version 3.0.0

Between 2000ft and 4000ft there is a big difference.
Top speed at 4000ft, should that be 395mph or 408mph?

FA_Whisky
10-17-2007, 11:10 AM
Look at this:
http://www.spitfireperformance.com/tempest/temptest.html
And compare that to the data from Il2 compare version 3.0.0

Between 2000ft and 4000ft there is a big difference.
Top speed at 4000ft, should that be 395mph or 408mph?

Wepps
10-17-2007, 11:43 AM
Under what conditions were they flown? What type of fuel and octane, was it a captured aircraft, was it damaged or new?

The chart shows 395 at 4,000.

edit - Wait I see it...

"The Tempest +9 lb curve is from Hawker, the estimates at +11 and +13/3,700 rpm are derived from Hawker data and curves."

Manufacturers had a vested interest in selling their aircraft to the government, so those numbers are often fudged.

The below chart to the one you are showing shows the same condition from the Focke Wulf people, being optimistic in their performance data.

VW-IceFire
10-17-2007, 05:08 PM
I'm not seeing the huge difference between in-game and the IL2 Compare chart. What am I missing?

Remember we have the +9lb Series II version and that the +11 and +13 charts are projections by Hawker based on the +9lb test flight they did. Also on the chart is a +8.5lb Series I with slightly less boost and a slightly disrupted aerodynamic profile (with cannon stubs on the wings).

I would say that given how close the A&AEE test is with the first half of the Hawker test and given the differences between the two otherwise that Hawker isn't really selling their plane too high in the actual testing.

I realize its wise to question the resources but some of the paranoia can be a bit much too. It would be bad for Hawker, with a plane that they are trying to sell which is based on another plane that has had a troubled development and has an engine made by a company not in favour to misrepresent the data significantly. I think its better to focus on if the data points are flawed in their testing regime...but in this case at least we have multiple testing establishments to go by.

Just some thoughts.