MiG-25 Engines

[Globetrotter]

Does anybody have any further information about MiG-25's engines tearing down if put to full power?? I've read this somewhere but don't remember where and would like to confirm,
Thanks,
Thomas

[Raptor]

I think i've seen that somewhere, but not sure... Russian engines are not the best that there are.

[Cobra2]

Yeah I've heard the same thing from multiple places.

[Raptor]

Ok. I made HERO before you, Cobra. Ha.

But the 'if-put-to-full-power' bit scares me. Do you think it'll happen?

[Gripen]

I heard that somewhere too.. Apperently theres somethin similar in the MIG-31.. but its only full power for a long period of time.. like hours

[valkyrian]

Russian engines not good?

Well, even the ancient, crude built, tumansky engines on the Fulcrum can operate flawlessly at angles of attack the F100&F110 never have been nor will be. The bigger AL-31 are working even with the Flanker flying tail first and without any FADEC control. Surely the MTBO (Max Time Between Overhauls) is 50% worst than the American counterparts but that's due to different philosophy. Once, Tupolev and C.L. Johnson were having dinner and Tupolev said to him "You Americans make airplanes like a Rolex, you drop it and it stops" (From B. Rich "Skunk Works")

The Mig 25's engines R-31, if operated at speeds>Mach 3, they tend to overheat and finally destroyed. This is because the combination of the high rotational speed of the compressor rotors and the flight speed. The result is tremendous temperatures that will melt the metallic parts. They have short life parts, but they are cheap to make. The DF30 of MIG-31 are very efficient. I don't know any other turbofan that can work from 0 - 3.1 Mach.

[Globetrotter]

Yeah, that's right, different philosophies, that's why I opened a thread about it

http://www.milavia.net/forum/index.php?topic=543.0

[Joopey]

The Mig -25 and its engines were never designed for long term mach3+time. Its was made to counter the B-70 and A-11/F-12/SR-71 threat and therefore needed only to 'dash' to mach3 and fire its missiles.

[Webmaster]

Actually, I am not sure there is any combat aircraft capable of even sustained Mach 2+ flight... let alone Mach 3. Sustaining supersonic flight is difficult enough for most armed combat aircraft already.

The MiG-25 needed carefull throttle handling at  speeds higher than Mach 2.6, or the engine would overspeed and the pilot would lose throttle control. According to some stories the plane would accelerate up to Mach 3.2 before the engine starts disintegrating, unless fuel was cut or it ran out of fuel. The popular explanation for all this is that the R-15 engine was actually designed for a cruise missile, but maybe it just wasn't good enough and the builder lacked enough knowledge about these flight regimes. The bypass system was just too simple to deal with the huge air flow. Anyway, you still have a Mach 2.83 capable interceptor/bomber/recce aircraft, and it lead to the MiG-31/DF-30.

I think it's time a proper MiG-25 book is published with developers and pilot interviews, there's too much talk and rumours and with even the most 'authorative' sources being pulled into question more and more, I am not sure what to believe any more.

[valkyrian]

Yes my friend, that's what i have read about the Mig's 25 engines. Built for a cruise missile. Considering how well this hand made, welded beast can fly prolonged mach numbers over unity is just amazing....

[Globetrotter]

I guess you are right, this is difficult to know in detail as the URSS was so closed to the west. And there are things I believe we won't know.... Though a book on this would be the ULTIMATE present for me, even if I have to buy it

[valkyrian]

I guess you are right, this is difficult to know in detail as the URSS was so closed to the west. And there are things I believe we won't know.... Though a book on this would be the ULTIMATE present for me, even if I have to buy it

There is a good book by Yefim Gordon on 25/31 i think it is in rapidshare for free.........