Aircraft peformances, is this joke ?

[ACE-OF-ACES]

Originally Posted by jf1981

I tested other parameters of Spit Mk I

- Stall speed is too low by approximately 15 mph flaps up, by 10 mph flaps down
- Take off run is longer by approximately 30%

Thought the take off run is not a so big deal, it shows that the reacceleration from medium and low speed time is longer, the performance is not as good as it shall be.

The stall speed, on the opposite, makes for better turns at low speed. It makes the gap between radius of turn of Bf 109 and spit wider than it should be.

Hey jf1981

You might want to hook up with klem and others who have been doing some testing.. In that what I have found over the years is most of the so called FM errors turn out to be pilot errors and or a misunderstanding of the test methods and or conditions. Not to mention all the little aspects of the simulated world that can have an effect on the results. For example something as little as the atmospheric conditions of the simulated world/map v.s. the standard atmosphere conditions that most if not all real world data is presented in. The following thread is a good example of which I speak..

http://forum.1cpublishing.eu/showthr...t=33077&page=5

With that said, if you really want to get serious about testing the FM than you have to get serious about collecting test data during your test flights. Here is a link to the C# script file that klem and others are using as a baseline for collecting test data during test flights.

http://forum.1cpublishing.eu/showthread.php?t=27552

Note it saves the data to a standard csv file format that you can use EXCEL or OpenOffice (which is free) to graph and compare the data.

I highly recommend you use this script during your flight tests! Because if you don't, when you make a claim, for example such an such is approximately 30% off, there will always be doubt as to if this error was due to pilot error or an error in the FM. By collecting (logging) the test data during the test flight you will not only be able to remove the word 'approximately' from your statements but also reduce if not remove any doubt as that the error was due to pilot error.

[jf1981]

Originally Posted by ACE-OF-ACES

[...]

I was as accurate as I could. Thanks for your links, we're really doing retro enginerring by now ....

[ACE-OF-ACES]

Originally Posted by jf1981

I was as accurate as I could.

Of which I had no doubt..

We all try to be perfect, but the fact of the mater is we are only human.

By collecting the test data during the test flight others will be able to review your test flight to see NOT only how accurate the FM is but how accurate your test method is.

Originally Posted by jf1981

Thanks for your links,

No problem if you have any questions, feel free to ask! But looking at FST's post he explains it step by step on how to use the C# script

Originally Posted by jf1981

we're really doing retro enginerring by now ....

Enh.. not really.

But the more standard we can make the testing of the FM the more useful the feedback we can provide to 1C

[jf1981]

Originally Posted by ACE-OF-ACES

By collecting the test data during the test flight others will be able to review your test flight to see NOT only how accurate the FM is but how accurate your test method is.

I used a method accurate enough for that purpose, the margin for error in terms of vertical speed and top speed is really a matter of few percents. Agree it can be nearly zero with a better method.

By retro engineering I mean flight testing in order to determine what was set inside the code.

By the way, could you have a look at the vertical speed dials ? I looked at the Mk II spit and got nonsense values, if you could check with you method, It would be interesting. I determined about 30% error low sea level and a 200% at 18'000 ft (the VSI higher by factor of 1.3 to 2 from SL to alt).

Aircraft IAS looks right versus map scale and time checks. Altimeter can only be assumed to give correct reading, I see no obvious way to cross check.

[winny]

What figures are you using as your real life ones?

The only reason I ask is that the usual figures for Mk I/II come from aircraft that were quite a bit lighter than BoB trim aircraft.

Any idea what the AUW is for your RL numbers?

[jf1981]

Winny,

"Spitfire, A Test Pilot's Story" from Jeffrey Quill
"Sigh for a Merlin, Testing the Spitfire" from Alex Henshaw
"The Story of the Spitfire, An operational and combat story" from Ken Delve
"Spitfire, The history" from Eric B. Morgan & Edward Shacklady

All being very good lectures.

[Jugdriver]

Just out of curiosity do these references give consistent data (same or similar performace) for any of the given Spit variants?

JD
AKA_MattE