Allright, I'm sick of conflicting stats on aircraft top speed. I research a plane and get the "official" top speed. Then I find other accounts from pilots, developers, etc. that are often higher than the "official" statistic. Here's some examples. The P-51D is supposed to have a top speed of 437mph. I've seen acounts of it doing around 445mph. The P-47M is quoted at 473mph while I've read that it could do over 500mph. My personal favorite: the XP-51G had a quoted top speed of 472mph while being quoted at 498mph elsewhere. So, my question is, are aircraft manufacturers and air forces delibertely trying to lie about their planes. I'm sure this is the case for other countries but I'm American and American planes are what I know best.
I have no idea on an individual basis. But I guess there are plenty of variables - altitude, atmospheric conditions, fuel type, fuel load, armed/un-armed, slight differences in individual aircraft, painted/upainted, inaccurate gauge readings... try not to get too irritated by it, it probably isn't worth the effort :wink:
I'd imagine the 'official' top speed was an average, which explains the variation. Some aircraft would be faster or slower depending on their age, airtime, and quality of construction, even if they were in the same production batch. Weather conditions would also have a considerable effect.
Okay, I found more stuff on the P-47M. They under-rated the top-speed for some reason. I can't remember right now. I think that average stuff is more or less right. Then there's field mods to engine and the plane body and what not that would change stuff. Thanks...
Also remembe that no two planes, and no two engines are exactly the same.
Even when you take an engine off the end of a production line. The next engine off the line, due to things like temperature effects and material grain, will not have the exact same performance as the previous one.
This is true by todays manufacturing standards and would have been even moreso during the 40s
allies build a plane, say top speed is 473mph. axis bring out a plane with top speed of 485mph to combat.
allies plane actually is 492. they engage................... axis pilot thinks WTF??????????? :wink:
There were lots of claims about top speed made in WW2.
The classic instance is the model 14, ordered by the British Purchasing Commision as the "Caribou Mk1". Bell had offered the aeroplane with specs provided from a highly polished prototype weighing a ton less than military production examples and were understandably annoyed to discover how lacklustre the new aircraft were on arrival in Britain.
The Germans sometimes encountered similar problems. Their aircraft industry were offering prototypes on a regular basis and the RLM were just as often disappointed with the 'less than expected' performance suggested by the manufacturer.
In some cases, aircraft were not allowed to achieve their full potential. Before hostilities, the Me209-I (under the false designation Bf109R) won itself the world airspeed record. Heinkel wanted that title for his products and began work on a special version of the He100. The RLM told him to stop work because it would be embarrasing for the Germans to have a faster aeroplane than their current front line fighter. Even worse for Mr Heinkel seeing as he'd already lost out in the propaganda war between the Bf109 and his He112.
There is therefore a great deal of difference in a top speed made by a solitary prototype, almost handmade, in as perfect conditions as possible, as opposed to a production line example weighed down with military equipment, subject to poor quality work due to circumstance, and flown by combat pilots instead of test pilots experienced in measuring performance. There is of course the propaganda angle as mentioned already, and the Germans made assiduous use of it.
Alford J Williams, a well known US pilot, had visited Germany before the war and had been allowed to fly an early 109. He was very impressed, and on reflection, announced he would rather fly it than the british spitfire or hurricane. Of course, Mr Williams had no experience of the british aircraft and thus was making this comparison on the basis of what the Germans had told him.
Speaking of speed. I can't get my P-51's over 220mph at 25,000 feet. I've been twiddiling with the prop pitch and the mixture and get little results. I've been using the UI 1.2 plane for a while and I don't see what the problem is.
lordish
Lordish, are you familiar with the difference between "True Air Speed" (TAS) and "Indicated Air Speed" (IAS)? In short, it means that the higher altitude a plane flies at, The LESS accurate the airspeed indicator reading is. This is because of the thinner air at altitude.
So your actual or TAS might be quite higher than the indicator says it is. (Also trim is really critical with the P51- but that's another subject).
Also from pilot to pilot top airspeed will differ widely depending on personal experience and skill. Whats the likelyhood the test pilot for each particular aircraft tested was an expert in that particular plane? I'm guessing they probably would be if it were a prototype but for production models I'd take the word of a veteran with years in the same aircraft over a test pilot with a few hundred hours in that same aircraft...how often have you considered your level flight speed to be as fast as you can go at the verge of overheating - only to be overtaken by someone in exactly the same model or a much earlier one (and I'm pretty sure production abnormalities aren't modeled in IL2). I'm not saying the test pilots at the time weren't experts in their field but I don't think I'd be considering their top speeds as gospel.
