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Old 20th July 2011 | 08:43
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Trim Stab
 
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A400M supra-divergent props

Looking at this photo of the A400M, it would appear that props 1 & 4 are supra-convergent (as one would expect to minimise P-factor) but that 2 & 3 are supra-divergent.

http://www.flightglobal.com/airspace...eglo-marks.jpg

Why has it been designed like this? There is presumably a substantial advantage of making the centre props supra-divergent, otherwise one would expect all props to be supra-convergent to minimise P-factor.

If the aircraft had a low tailplane I would hasard a guess that it would help reduce tailplane drag at some flight regimes, but surely the high T-tail is not affected by prop upwash from the middle engines?

Or is it to reduce the total prop downwash over the wing to reduce dihedral effect?

Last edited by Trim Stab; 20th July 2011 at 10:25.
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