Spit IIA Speed in game test

[ATAG_Snapper]

Originally Posted by 5./JG27.Farber

You doing it wrong. At 100m's I get 460 Km/H IAS at 1.3 Ata and at 5km's I get 420 Km/H at 1.3 Ata...

I have tracks if you want them.

No need for tracks from you, Farber, AFAIC. As with IvanK, if you say it is, then it is.

[5./JG27.Farber]

Thats going in my sig...

[Crumpp]

Originally Posted by IvanK

Attached graphic is my Speed test in CLOD current version + Hot fix.
Blue Line my results, Broken line Spit I spec, full line Spit II spec

METHOD
Each run commenced on altitude with stabilised Oil/Rad temps Oil Temp at 80deg C. Rad Full open (At present I cannot detect any Rad drag so radiator position is not relevant imo)
Each altitude was a specific FMB set up. Altitude maintained +-50ft throughout the test. QNH checked as 992mb on the specific map used.
Each run done 3 times and Vmax average plotted.
Seal level temp estimated 19 deg C based on HEIII OAT gauge on the same map on the ground. TAS calculation based on standard 2 deg C lapse rate from the surface. so at 16,000ft I was using an OAT of -13deg C
My test wt 114lbs less as reported by FMB than the spec wt

Power setting was Full throttle 3000RPM. Indicated Boost +6. Now its important to understand that displayed Boost is not I believe actually measured in the FM but represents an angular animation value. We all know that it should be indicating +9 in the Spit II.

I gave up testing at 17,000ft as things were radically different from the spec values.

Results plotted as accurately as I could.


If someone wants to convert the test values to Standard day figures ... go for it.

It appears a little pessimistic.

Ballparking it off the data you gave I get your Density Altitude at 14000 feet as ~15500 ft.

It looks like the FTH then is ~1000 feet low and the aircraft is about 3% off in SL Vmax.

[klem]

Originally Posted by ATAG_Snapper

I've also found a pronounced difference in FM for the Spitfire IIa between offline and online. The two FM's are the same at SL, but I found the IIa's online FM takes a remarkable departure from the offline FM as altitude increases.

Snapper, try adjusting the Altimeter barometric setting in both cases at the same field until it reads zero feet or as near as you can get. Is it the same baro setting in each case or are you seeing different atmospheric conditions?

In my own created server and in ATAG I find the correct setting 'on line' for Tangmere (which is about 39feet) is 995mb. Based on that I set 995 at Manston and get 140 feet in both servers. IOn off-line single mission Free Flight over England after landing Manston I have to set 996 to get 140 feet. So different types of 'day' perhaps?

[ATAG_Snapper]

Maybe that's it, Klem.

Except, the Ia's FM's agree very closely under the exact same test conditions offline vs online. The IIa's FM's do not.

[5./JG27.Farber]

Me and my wingman often have 200m's defference staring from the same field on our altimeters.

[ATAG_Snapper]

3% off in SL Vmax?

((267 mph TAS actual - 287 mph TAS spec) x 100)/(287 mph TAS spec) = -7%

or am I doing this wrong?

[klem]

Originally Posted by 5./JG27.Farber

Me and my wingman often have 200m's defference staring from the same field on our altimeters.

??!!

Both have same baro setting?
Reading from the tooltip or the gauge needle?
Tooltips are to nearest 100 feet in RAF planes so one a/c at 90 feet and one at 105 feet will read 0 and 100 respectively.

Or the 109s are porked and next time I will run from a 109 at 25 feet and see what happens behind me

[5./JG27.Farber]

We both take off and he'll say 2000m's and Ill say what? we are are at 2200. Read from the needle.

[IvanK]

Easiest way to set accurate QNH is set the Altimeter to the field elevation. Field elevation can be found in FMB. Attached file has every airfield's elevation in the Sim all obtained from FMB.

A 1mb error should only result in 30ft/10m error.

I do believe the default maps have some diurnal variation in both Temperature and pressure. I too have seen 992mb as the setting on ATAG at some times and 995mb at other times.