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The Tupolev Tu-95 "Bear" seems like an awfully cool piece of innovation with its unusual contra-rotating supersonic-tipped props. From what I've been reading it sounds like it's been the only mass production airplane to use props at those speeds (there were apparently a handful of American examples as test aircraft but NASA abandoned the project?).

I'm curious what profile of blades they used. I know there are lots of supersonic-capable airfoil shapes out there, but it's not clear which if any of these were used for the Tu-95 props, or even whether a fixed wing supersonic blade profile is appropriate for a prop. Any ideas?

Aaron Altman
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    Arguably, it was, in a way, something opposite: a safe bet technology chosen in preference to the true innovation: a jet engine (on a long-range aircraft). – Zeus Aug 06 '18 at 02:41
  • The TU-95 propellers are not the only ones whose tips operate at supersonic speeds. The catch is that doing so requires significantly more torque from the engine to overcome the drag from the supersonic tips. That's why the engines on the prototype TU-95's had to be discarded and replaced with more powerful ones when the aircraft entered production. I can't find any source for the airfoil used on those propellers. – Juan Jimenez Aug 08 '18 at 12:20
  • @JuanJimenez what are other examples? The XF-84H is the only other one I know of. – Aaron Altman Aug 08 '18 at 16:49
  • Every turbofan out there uses fan blades whose tips operate at supersonic speeds. The fan blades are just like propellers, except that they are "caged" in a way that overcomes the problems with propellers trying to operate at those tip speeds. Some turboprops can also operate briefly in that range but the problem is that it greatly reduces propeller efficiency and increases metal fatigue. – Juan Jimenez Aug 10 '18 at 07:50
  • The XF-84 was quite different: Spinning at 3000 RPM, most of the XF-84 prop blades' was at supersonic speed. The 850 RPM on the Tu-95 actually minimized the supersonic blade section. – Peter Kämpf Feb 01 '19 at 15:31
  • See here: https://i.stack.imgur.com/UhDpb.jpg – Pheric Feb 01 '19 at 16:52
  • @Zeus (I'm aware I'm replying to an old comment) arguably it was a damn good bet, not that many designs from that era are still in active use. The Bear has truly overcome the test of time. – Jpe61 Oct 05 '19 at 20:48
  • @Jpe61, …. except it's direct counterpart, which first flew earlier in the same year, the B-52! – Jan Hudec Oct 05 '19 at 22:24
  • Slight frame challenge, the tips might not be supersonic in cruise, only at maximum speed: "The propeller diameter is 5.6 m and their speed is 750 RPM, so the circumferential component is 5.6⋅π⋅750/60=220m/s. Add to this the cruise speed of Mach 0.67 (taken from this site — others list quite incredible numbers) at altitude, where the speed of sound is 295 m/s. Mach 0.67 equates there to 197.65 m/s, and vector addition gives 295 m/s for the propeller tips, exactly Mach 1.0. This means that the propeller is subsonic over its whole span." – AEhere supports Monica Oct 05 '19 at 22:39
  • @Jan Hudec yep, hence not that many designs and not no designs :) – Jpe61 Oct 06 '19 at 04:59

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The propellers were designed by OKB-120 headed by K.N. Zhdanov, type AV-60N. This type was used on a few other aircraft, but unfortunately I can't find any further details about it. Can somebody visit one and inspect it?

Camille Goudeseune
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