Russian-Aircraft Variable-Geometry Inlet Use (Cold-War Predominantly)


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13 February 2008
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I remember reading awhile back that no russian aircraft used variable geometry inlets during the cold-war era and for some reason it was technology they didn't develop much.

But more recently I've done a little research and it would appear that the Su-7, MiG-21, Su-9, Su-11, MiG-25, some of the Su-17/Su-20/Su-22, do have variable-geometry inlets although I'm not sure of the exact details. From what I read the MiG-21's inlet was a two-position inlet controlled by the pilot. I would assume the Su-7, Su-9, and Su-11 are probably very similar since they're of the same era about. I'm not sure about the Su-17/Su-20/Su-22 designs -- they look very similar to the Su-7, MiG-9, Su-9, and Su-11 though. The MiG-25 actually uses a moveable ramp system much like some of our fighters do. It even has slots and holes and such (porous to control turbulent flow although those holes are pretty big) in the ramps. Whether it's a two position, or multiple-position set-up, and whether it's pilot-controlled, or automated I have no idea. I would assume the MiG-31 would because of it's high-performance capability and it's roots in the MiG-25 design.

I don't know about the Su-15, Tu-28/Tu-128, MiG-23 or MiG-27, Su-24, Su-27, (and/or all it's derivatives) and MiG-29.

Anybody know for sure?
The Su-15, MiG-23, MiG-29 and Su-27 (as well as most later derivatives, excepting the Su-34) have variable inlets. So did the Su-24 originally, they were fixed on production airframes however. No idea about the Tu-128.
Then where did this myth come that the Russians didn't have the technology? A sizeable number have them.

KJ, I've never heard of this "myth", hence I can't really comment on it. Its patently absurd, as plenty of Russian aircraft used variable geometry inlets. Indeed, they stuck with them on Su-27 and MiG-29 when the US was going to fixed inlets.
I would assume the same would apply to the bombers -- the Tu-160 uses variable geometry inlets. Does the Tu-22M?

Also does the Tu-144 or any of it's variants use variable-geometry inlets?
Yes on all counts.

It has been suggested that the MiG-23's variable intake was loosely based on examination of a crashed F-4 from Vietnam. Early conceptual models of MiG-23 used semicone bodies in their intakes, F-104/Mirage style. The MiG-25 wedge variable intake was inspired by the A-5 Vigilante.

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