In the following link to Mike Williams Spitfire Performance website you'll see various documents petaining to the F4F's performance however on another forum another poster is saying some of these documents are just official statements on an aircraft's performance not what it actually could do. However it seemsd most to me seem based on flight tests. Your opinion??? F4F Performance Trials So isn't this one based on actual flight test or at least operational input???? And not some pencil pushers'calculations. http://www.wwiiaircraftperformance.org/f4f/f4f-4.pdf or this one??? http://www.wwiiaircraftperformance.org/f4f/martlet-I-ads.jpg it seems to me all documents/reports like these are from flight tests or reports thereof.
Flight performances should always only be used as a guide...Great for arguements on couchs/sofas but each aircraft was different and had a different age and experienced different operators...they age the moment they leave the factory...weather conditions will alter ALL the data anyway...but these figures can be used as a comparative guide between different types of aircraft. If they differ from publication to publication, they could be talking about another marque, or based on "original" testing...earlier marque. Or as happens too frequently, they are just wrong.
Oh I realise all of that but most of those documents are primary sources not something quoted by an author. In the Grumman Detail Specification for the F4F-3 at around 7105 lbs(which including armor and self sealing tanks) the plane was SPECIFIED to climb at 3300 FPM and take 7:30-8:00 to 20K but in a flight test aircraft #1848 only achieved like 2500 FPM and about 10:00 to 20K though it came in at 7065 lbs however inreading the report/test the plane had some engine problems which probably held back it's performance.
Precisely...no aircraft will perform EXACTLY like the next...the engine loses horsepower very soon after operational use...weather conditions, hot air (less dense) cold air, creates dense air and extra drag to the aircraft, wing tuning to hot, warm, cold air...boost performance...please dont say you realise that...becasue you obviously arent taking all theser factors into account...You have two Ford racing cars, one 3 weeks older than the other, you put them on tracks at different times of the day, cold morning air for one, the other in the midday heat...will these two identical cars go round the track at in the same time?
When I said I realised that I meant I know alot of things affect performance . I just wanted an extra opinion or two on the issue of wether or not those documents were gathered from flight tests or not another poster elsewhere is trying to say all those documents are basically from some pencil pusher estimating an aircraft's performance.
Well thats BS for a start...Sure you can have general "books" on the subject...i have about twenty aircraft "Bibles"...and its tough getting the same figures in each, in these cases, i'd take the figures purely as a guide. But if you take the figures from the official manual or documents released under the manufacturers name then you can trust the figures (within the parameters set above). Of course be sure you are reading the ACTUAL figures, not the brief/specs given to the company...the two rarely match. The figures can be obtained by either a straight flight test, or a "lab" test using measureing machines...these are "pure" results in best conditions.
Most flight "test" data from manufacturers is calculated performance, most data from military sources are from either service use experience, or direct reproductions of specific flight tests of individual airframes under specific flight conditions, which will all be described and a tail number will be recorded. With military sources (including many documents at Mike's awesome site), most figures must be regarded as averages by any objective researcher. Normal variation runs to around 8% iirc, plus being conditional. With manufacturer sources (including many German documents, such as MttAG or FW docs), are in fact calculated performance charts unless a specific werk nummber is listed, even if an aircraft condition is given. Without a werk nummer it's always a calculated chart, like say, charting Fw-190D performance fitted with a DB-603G engine. Never happened, but there's a wartime performance chart for that configuration. It's just math.
