[Viper2000]

Originally Posted by Sternjaeger II

de facto making it an interesting read, but not quite the reliable reference that we need

It's pretty easy to untangle the typographical errors because the conversions are in parentheses, obviously added by the typist after the fact. You can just ignore them and then it's all good. In any case, the conversion errors tend to be glaring - provided that you know roughly what the correct answer should be, it's pretty easy to weed them out.

The main advantage of Brown's test results is that they are internally consistent; it's the same guy flying all the aeroplanes, so you get a real comparison between aeroplanes rather than a comparison between pilots.

This is especially important when you come to consider handling, since it was strength limited in large parts of the envelope, particularly at high speed.

His tests of German aeroplanes are especially good because of course his German was good enough that he understood the captions in the cockpit, could interrogate pilots & ground crew, read manuals if available etc.. This means that there's considerably less risk of under-performance due to poor technique than might otherwise be the case.

Originally Posted by Sternjaeger II

now that's interesting! I have the older version, bugger!

I think that he decided that the statute of limitations had expired for the latest edition... AFAIK he just flew the thing for the heck of it, on the basis that the fuel was going to be disposed of and the aircraft scrapped, so why not? (Other than the obvious health & safety issues of course).

Originally Posted by Sternjaeger II

The thing that you point about the Ta-152 happened with other planes as well: the incorrect use (or lack) of fuels meant that they were more general handling tests instead of performance ones.

This sort of thing applies to all captured aeroplanes; you have to read the small print very carefully so that you know what you're actually comparing.

The lack of MW50 & GM1 doesn't necessarily fatally compromise the Ta-152 tests, since you can calculate the additional power which they would have provided and hence deduce what the maximum performance would have been. Of course, to do this properly you need to have enough other test data to infer the shape of the drag polar, but you only really need this information for a relatively narrow range of CL. It's really amazing how much you can deduce about aircraft performance from quite limited data. In fact, some people make careers of it.

For example, one of the main reasons for scrupulously fitting exhaust nozzle blanks to shiny new fighter jets when they're in the static park at an airshow is that if I know the nozzle throat area then an experienced observer estimate the engine thrust with rather better accuracy than the layman might expect.

In any case, the handling is generally more interesting than the kinematic performance, since it's far easier to calculate kinematic performance than it is to calculate handling characteristics, especially at transonic speeds.

[QUOTE=Sternjaeger II;281235]apparently it was just a genuine performance test to see whether they could improve the handling of their 109s, have a look at this interesting article
http://www.unrealaircraft.com/hybrid/spitfire.php

I think I might have come across this before at some point. The comparison argument is a strange one, because firstly it's irrelevant to combat, and secondly no two installations are alike in any case.

Since the Germans weren't stupid, my best guess is that:

1. They expected engine failure, and therefore opted to premptively replace the engine.
2. They realised that the Spitfire V was obsolete, but since they didn't have high performance fuel they couldn't investigate its development potential by over-boosting the engine; therefore the only way to investigate the aircraft's ability to handle extra power was to add the next generation of DB engine instead.

In the latter instance, this would imply that they were yet to capture a flyable Mark IX or XII.

It's worth noting that the RAE, with access to high grade fuels, took the former route with their early captured Fw190s, handily exceeding rated boost (and possibly rpm, though I'd have to check my copy of Wings of the Luftwaffe). I suppose this might technically be called the fly it like you stole it approach...

Originally Posted by Sternjaeger II

this proves though that surely there are other tests that have been made and data has been collected, sourcing it is another story though..

I have no doubt that the Germans collected vast amounts of data on a myriad of subjects, since that is their nature, but I suspect that a lot of it either went up in smoke some time in 1945 or else was carted off by one or other of the victorious Allies (most likely the USSR or the USA; the British mission essentially consisted of whatever Sir Roy Feddon could beg or borrow, and much of what he obtained was instantly stolen at gunpoint by the yanks...).

However, it's important to remember that the Germans were under no obligation to (for example) use the same standard atmosphere assumptions as us, or to test their aeroplanes according to the same methodology. So if you want to make a really satisfactory comparison it's not sufficient to just perform a unit conversion and overlay the data; you've got to actually drill down to find out what the assumptions underlying the test results were, and then correct everything to a common standard.

Otherwise it's apples vs oranges.

I think I went into this in my flight testing thread.

Hopefully in a few patches time, when things are sufficiently stable for serious testing, we will have amassed enough of this underlying information on assumptions to allow everything to be converted to modern ISO standard conditions so that fair comparisons can be made.

However, since I don't have a great deal of German data on test methodologies, German standard atmospheres and so on, I'm very much reliant upon the wider community to fill in the gaps.