Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: Urchin on May 04, 2002, 01:24:28 AM
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Anyone have any of the British tests? I'm really curious about the roll rate, because I was under the impression that the 109E4 could out-roll the Spitfire I. This isn't the case in Aces High- it isnt even close.
Spit I has a 360 roll of about 6 seconds each way (left and right, I only tested it 3 times each way though) at 200 to 250 mph, at 300 mph the roll time increases to about 7 seconds (maybe a little worse than 7).
109E4 has a roll rate of about 8 seconds going left and 7 seconds going right at 200 and 250 mph. It didn't seem to get much worse at 300 mph, remained about 8 seconds both ways.
Also seems like the Spitfire starts the roll a lot faster, if you know what I mean. 109E seems like it has to take a bit to figure out you just threw the stick to one side, then it starts ponderously rolling.
For comparison, the 109F4 has a 5 second roll to the left and a 4 second roll to the right (and it also doesnt have that 'your stick is buried in a bucket of cement' feeling when you start the roll. What was changed to bring about this drastic improvement in roll performance?
I know the 109F series switched to rounded wingtips instead of the squared off ones- but the RAF switched to squared off wingtips in their Spitfires to improve rolling performance. So what could it be?
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I believe spitfire rolling performance was not improved because the wingtips were "squared", but because the clipped wings had less wing area, were lighter and the moment of inertia was moved inward.
Hooligan
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Whats a 'moment of inertia'? Also, the wings were smaller by a little bit, I think 10-12 square feet. Don't really see how they could have been a whole lot lighter though, the same stuff was still in them.
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i think thats true at high speeds urchin
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You think what is true at high speeds?
I don't consider 200 mph to be high speed. Not even for a 1940 plane. 300 mph, sure, I'll grant you that may be high speed, and I wouldn't be surprised by poor rolling performance at that speed- but 200 mph seems far to low a speed to have a 7-8 second roll.
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Galland said the Bf109E was abel too outurn a spit in the first 270 degrees of a turn. After that the spit would take over.
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I'm not concerned about turning. In fact, I think the 109E4 turns pretty damn well. What I am a little concerned about is roll rate. I just want to know why it rolls so horribly, especially compared to the Spit I and 109F4.
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Yes I have the tests, will post em later. The only real thing they say about roll rate is that at 400mph, both the Spitfire Mk1 and 109 E4 needed 4 seconds to roll 45 degrees.
Will post some more interesting reading from the tests later.
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hi guys,
the pilot/ex-owner of the 109e7 in the usa said, that
the Emil outrolls the spitfire.
will look after the article...but well..its in german.
habicht
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Originally posted by HABICHT
hi guys,
the pilot/ex-owner of the 109e7 in the usa said, that
the Emil outrolls the spitfire.
will look after the article...but well..its in german.
habicht
Wonder if the owner of a Spitfire would say the opposite?
-Sikboy
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http://www.fourthfightergroup.com/eagles/bank45.gif
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Both the Emil and the Spitfire I rolled badly at high speed, and when entering 400mph they hardly rolled at all, the Spitfire being slightly better if anything.
In the case of the Spitfire, the ailerons were to blame, for they were canvas clad. Problem was solved by installing metal ailerons from MkV onwards. The clipped wing came later, that was to counter the insane roll rate of the 190.
The 109E apparantly had some aileron problem, and in version 109F onwards a new type of ailerons were installed.
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Yup, I have the tests. 109 report is about 56 pages though. The conclusions, however, are on my Spit I (http://www.fourthfightergroup.com/eagles/spit1.html) site. There's some nice roll and turn diagrams to be found there too. Bottom line is the Brits thought the 109 handling was very nice under 250 mph. Above 250 it was a total pig and " It does not possess
the control which allows of good quality flying and this is particularly noticeable in acrobatics. "
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Urchin:
Moment of Inertia is errr.... the rotational center of gravity :).
If all the weight of the wing was at the wingroot it would not take much force to get the wing rolling. If all the weight was at the wingtip, it would take a lot more force. The center point for the wing moved inwards when they clipped it, making it so that less force is required for a given acceleration in roll.
Also there is less wing area so less air resistance to rolling motion. A lighter wing also helps. Apparently the 3 factors together make a big difference. My point was that shortening the wing helped the roll rate (for a variety of reasons). Since the 109f wing was not shortened it was not getting the same benefits, although removing wing armament should have surely helped the 109f.
Hooligan
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hooligan you are not exactly correct
the moment of inertia you are speaking of is Ix, moment of inertia about the body x-axis of the aircraft. It would have little to do with maximum roll rate, but has a large impact on stability in roll and on roll response.
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Look at Wells link, shows that the 109 outrolls the spitfire by far when bellow 300mph. Spitfire takes over at about 310mph. Bellow 270-280 the difference is really big.
In AH the spit outrolls the 109 E in all speeds at all alts.
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It looks from that link that the rolling performance of the 109E is actually pretty close. In my 'tests' I averaged about a 7 to 8 second roll from about 175 all the way to 250 or so. In the link, it says the 109E takes roughly 1 second to go 45 degrees. That'd be an 8 second roll. It doesn't say which direction the roll was made in (I don't think).
However, if those tests are accurate the Spit I is rolling far too well. It says in the test it takes a little under 2 seconds to roll 45 degrees up until over 300 mph (where it gets worse fast, just like the 109E). In my 'test' the Spitfire got roughly a 6 second roll from 200 to 300 mph (in both directions). That is about 3/4th of a second for a 45 degree bank. Therefore, if the tests are accurate the Spit I rolls about 2.5x as fast as it should be rolling.
That wasn't my primary concern though. It looks like the poor roll ability at all speeds is modelled correctly for the 109E, and that was what I was wondering about.
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Not that I want to hijack this thread...but....
Many of the planes in AH probably need to be tweaked, in terms of both speed, climb and rollrate.
The A6M5 for instance, rolls way to good at high speed..I belive even better than the 109 or Spitfire I, while in real life it was almost unmovable above 300 mph...
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Then it is the spit Mk1 that needs to be fixed and not the 109 :)
The zeke is a weird plane, quite often capeble of outdiving many faster planes...
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What's the source for that chart in the link :confused: :confused: ???
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