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Subject: How to fix the design defects of the Spitfire airplane of WW-II.
Shooter    5/26/2005 5:12:16 PM
Given 20-20 hind sight, It is easy to see where R.M. went wrong with the Spitfire! The following list of items is my idea of how they should have done it, IF THEY HAD READ ANY OF THE COMMON TEXTS instead of designing a newer SPAD for the last war! 1. Start with the late Seafire or even better the Martin Baker MB-5! they have contra props and wide track gear. The MB-5 also has a much higher LOS out of the pit forward. This is also one of the Spits larger problems. 2. Change the shape/planform of the wing and eppinage from eliptical to trapiziodal. The eliptical surfaces caused the construction time and cost of the Spitfire to be more than double that of the Mustang and almost as much as the P-38. 3. Reduce the wing cord and thus area by 35-40%! This reduction in surface aria will increase the cruising speed substantialy! This is probably the single biggest defect in the design. The change in aspect ratio will also help fuel ecconomy! 4. To compensate for the increased landing and take off speeds install triple slotted fowler flaps with a long hinge extension. This gives a huge increase in wing area and changes the camber for supirior "DOG FIGHT" ability, should you ever need it! ( because the pilot really screwed up!) At full extension and deflection, they would reduce the landing speed by 11~13MPH? (Slip Stick calcs!) 5. Remove the wing mounted radiators and install a body duct like the P-51 or MB-5! This one change would add ~35MPH to the plane? 6. use the single stage griphon engine and install a "Turbo-charger" like the P-38 and Most American Bombers had. This would increase power and save weight, both significant contributers to performance. 7. Remove the guns from the wings! This would lower the polar moment of rotation and give the plane snappier rates of roll! It also makes room for "wet wings" with much more fuel. A chronic Spit problem. It also fixes the Spit's gunnery problem of designed in dispersion! 8. Install the Gun(s) in the nose! Either fireing threw the prop boss/hub or on either side 180 degrees either side of the prop CL. This fixes the afore mentioned dispersion problem. One bigger gun between the cilinder banks or upto four 20MMs beside the engine or both, depending on what your mission needs were! 9. Make a new gun based on the American 28MM or 1.1" Naval AA ammo! This shell was particuarly destructive, had a very high MV and BC and was all ready in service. A re-engineered copy of the existing gun to reduce weight and increase RoF is a faily simple task. Pay the Americans for it if British spring technology is not up to the task! it also frees up much needed production capasity for other things. 10. Design a new drawn steel "Mine" shell for the above gun! Spend the money to load it with RDX instead of the TNT used for the first 4/5s of the war. 11. Pay North American or Lockheed to design it for you, since the Supermarine staff was to tied up fixing the origional spitfire design to get it done any time soon. Did I miss anything?
 
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AussieEngineer    RE:Cross Post - Critique of the P38 - link instead   2/4/2006 9:23:41 PM
 
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larryjcr    RE:Cross Post - Critique of the P38 - link instead   2/4/2006 10:47:56 PM
The graph for the standard wing Spitfire shows a maximum roll rate of 105 deg./sec. which is slower than the one I quoted from a Spitfire site (140 d/s.) Actual combat pilots in Europe agreed that the two best rolling a/c were the FW and the P47, which makes the graph for the latter seem odd. Pilots who flew P47Cs against MkV and MkIX Spitfires found that they could out roll it by better than 2 to 1.
 
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MustangFlyer    RE: Roll Rates   2/4/2006 11:35:10 PM
Great document. Shame the Me-109 isn't there. Consitent up with some other stuff I've read. Yes the P-47 was better than a standard wing Spit at high speed, same as the Mustang, which was even better. Given the mass of a P-47 a very respectable result. The big issue for the Spit was wing twist, a price paid for being so thin. I didn't know just how good a clipped wing Spit really was. I'd read some reports and stories about them (Spit XII and clipped IX and XVI paticularly) but nothing definitive. Must have made a late model IXB/XVI with 25lb boost a formidable opponent. For Larry, further backs up the P40 being pretty good at low altitude and lower speeds. Probably a match for a Me-109 up to 5,000 ft (maybe a bit higher).
 
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AussieEngineer    RE: Roll Rates   2/5/2006 3:57:56 AM
you can read the whole report if you want http://naca.larc.nasa.gov/reports/1947/naca-report-868/
 
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AussieEngineer    RE: Roll Rates   2/5/2006 7:56:16 AM
I've posted this before, it's the chart from report 868 but with a few extra aircraft added. http://img461.imageshack.us/img461/7789/7151128252798bf109roll50lbs4mx.gif">
 
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AussieEngineer    RE: Roll Rates- This was actually the one I wanted to post   2/5/2006 7:58:59 AM
But the last one is pretty good as well http://img461.imageshack.us/img461/6066/rollchartclr2w1098xg.jpg">
 
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AussieEngineer    RE: Roll Rates- This was actually the one I wanted to post   2/5/2006 8:02:04 AM
That is what makes me suspect something is out of kilter with the 200 deg/s P-38 roll rate, this chart and the one I posted previously show it struggling to make 100 deg/s.
 
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MustangFlyer    RE: Roll Rates- This was actually the one I wanted to post   2/5/2006 8:08:47 AM
Yeh thats makes sense. Higher angular momentum. You can see the effects of the boosted ailerons at high speed. Note how the planes with Freise (or is ot friese?) ailerons have that characteristic hump. Clever work laddie. You've overlayed the Me109 & P38 on the NACA chart. Where did you get the other data from?
 
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AussieEngineer    RE: Roll Rates- This was actually the one I wanted to post   2/5/2006 8:55:08 AM
Can't take credit for it,I didn't do the overlay. I pulled the pics from another forum. I'm not sure what their origin is but I'm fairly sure the data is accurate.
 
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larryjcr    RE: Roll Rates   2/5/2006 10:55:03 AM
Yes, I recall. I was somewhat critical of it because it wasn't for maximum roll, but rather, for the roll at one particular control force level. Since more force was possible (note the force level for the '109) and the Spitfire had notoriously sensetive controls, it rates higher compared to the others than if it was a maximum possible roll rate test.
 
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