Curiousity Regarding MiG-25 Top Speed

nele

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Hello, this is my first post here ::)

While SR-71 is true M3 aircraft, MiG-25/31 is/are true Mach-2 aircraft.
If the meaning for both is "can fly that speed at most of the operational flight time".

M2.83 limit on RB is determined by engines, heat-load of airframe and stability of the -25. Roughly in that order (although 2.83 is aerodynamical limit). Also, engines can get in runaway, in spite of electronical fuel system, and can achieve temperatures after which they have to be promptly changed.

MiG-25R did fly faster than M3 over Israel. Pilot Bezevec (Russian) did it, accidentally and very shortly. It was not M3.2, but 3, engines stripped, checked, without damage.

To make it operational... have I mentioned that it was MiG-25 pre-series, supervised by MiG Buerau, and Bezevec was test-pilot? And because of death of General Kadomtsev in-25 , MiG Buerau had to "prove" itself?

With engines changed (on -25M prototype) it could do M3 with ease, but its fuselage integral tank blew when they tried to make it sustai ned. The inert gas system had had to be modified, too. As well as lot of other things that might seem irrelevant (fuel system could not "follow" the engines, for example).

But, it would not be cheap enough then to make 500 of them... ;D
 

r16

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while this always carries the risk of being banned or having the topic locked , ı think ı should have one more fling as I will be the first to accept that my posts are really unsupported and even though ı could well claim their authenticity I still owe it to the seriousness of this forum to display my whole range of style to enable those who bother to check them to evaluate their reality .

ı had written a couple of posts at home and I wholeheartedly agree that they can be deleted if unsuitable.
 

r16

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from Air Forces Monthly December 2004

Swedish radar posts knew the SR-71 flights usually about an hour before it arrived . The plane would make a tour over the Baltic Sea that took 30 minutes to fulfill and always flew the same pattern . It would be around 70 to 80 thousand feet (21.3- 24.3 km of altitude ) At these heights according to Swedes it was under threat by Su-15s while Mig 21s and 23s were not up to it .Rolf Jonsson ,a retired Swedish officer says this about the Migs :

"... their trails on our radar screens in Sweden were so harmless it was painful ! "

on the way back SR-71 would cross between two Swedish islands though it would be still in international airspace and I think the Swedish Viggens were also making practise runs on it .

so far no Foxbats but as the Blackbird was going out of Baltic , a single Mig-25 would be in the air and it would intercept the USAF plane flying at about 72 000 feet .The Russian plane would climb up to 63 000 feet ( 19.2 km) approaching to 1.6 nm and return .The precision impressed the Swedes for the 10 years of Blackbird operations over Baltic between 1979 and ' 89 . The author of the article Paul F Crickmore thinks :

"... the simulated attack consistently terminated when the interceptor was at 63 000ft (19,202m) and 1.6 nm (1.8 miles or 2.9km) behind its target This would seem to suggest that these were the parameters necessary for its weapons systems to effect a succesful intercept if the order to fire were ever given .However this , of course ,will forever remain merely supposition."

ı'd say this was the Russian way of saying "You are dead" to Americans . 3 km is approximately the minimum launch range for AA-9 and it might well be the norm for the AA-6 Acrid , the standart Foxbat weapon .And it is the maximum for AA-8 .Breaking at that range signifies the mission is over .

This is of course not the SR-71's limit . If it was Viktor Belenko wouldn't have said that SR-71 flies too fast and too high and it is uninterceptable by the Mig-25 as the missiles are limited to 27 000 metres and " as you know , the SR-71 cruises much higher ." These are statements contradictonary to what I have so far preached and you can take my word that I don't believe the conclusion . While it may be true that Acrids lacked power to overtake the Blackbird in a tail chase and the fuses to down the American plane in a head on engagement , they would have killed their target most of the time . If they weren't capable of doing it ,the Russians wouldn't hung them up on the Mig - 25 .

the Belenko case has always been played only for propaganda ; afterall he really landed at where he should have intented but the book I have tells it as if it was some kind of a miracle . And the crowning part is probably where they build a road of 4 miles for the defence minister to be driven to the airbase from the helipad .Why doesn't he land directly on the base I will never know . Maybe Russian helicopters can't land on airbases due to design deficiences and general Russian backwardness . Anyhow to cut it short the entire airfield staff , including the aviation personnel do the deed in great expense and even cover the sides of the road with hundreds of trees .It is July and hot so the a second batch of trees are planted .By August the minister is ill and the visit is cancelled . But as the pilots have lost their proficiency since there were so few flights since May , one of them has a mishap overrunning the runway and slicing a passing bus , killing 10 . So Belenko defects in September.

really ?
 

r16

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ı don't have the time to write at web cafes , so ı type my "papers" at home , and the problem then becomes that they do fall short of the subject being discussed at that particular moment . With apologies if this is once more a serious diversion.

Alan Dawes in his December 2002 article in Air International says that it was "possibly" for maskirovska purposes that the MiG-31 was called product 83 compared to Foxbat's 84. I object .

the "big MiGs" are weapon systems first and it would be most realistic to assume that MiG-25 /31 series were conceived at least simultenously , but as it was unpractical at the time due to deficiencies in avionics the Foxhound was discarded . The Russian industry could not provide the necessary means to conduct autonomous operations in the Far North .Yeah ,the Tu-128 you might say but I don't think the Fiddler's objectives include interception of high speed targets .When it comes to the demands of Nuclear War ,the B-52s are small fry.

the Foxbat on the other hand was a simpler option as it depended on GCI and the infrastructure was already there.On the performance issue I have a long winded explanation .In a Bill Gunston book I have somewhere ,he mentions the Mig-31 illustration might be wrong since it shows water methanol pipes for the inlets , presumably to cool the air in the inlet in a similar way to PCC method that could have given a Vmax of mach 3.2 to Phantom. But as the Foxhound is known to be slower it doesn't need them . Now I have to admit that I wouldn't know a water/methanol pipe even if it came up and bit me but the sole reason for their presence on the Mig-25 should be because of the fact that Foxbat needs them to perform its mission . It is a weapon system and the airframe is a part of the greater sum ; with the weaker rocket motors of the era the plane has to be faster to overcome deficiences in the weapons themselves . As soon as the Russian industry could provide the necessary items , the Foxhound would take over . Article 84 is an interim solution.

just like the analogy of Spitfires .While waiting for the ultimate Griffon engined XXs , XIVs and the far more familiar case ,IXs rushed into service before the ultimate Merlin Spitfires, the VIIIs.

starting from documented real cases to what I presume to be reasonable analysis. Anyhow it is got to be the first time that you have seen such a claim.
 

r16

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such a drastic action of getting a second best at huge cost could only be justified by the magnitude of the thread .From the same issue of AFM we learn a Blackbird had an engine explosion and had to get lower .The pilot of the American plane , Maj .Duane Noll said

"We later found out that the Soviets had launched numerous fighters with orders to force us to land in Soviet territory or shoot us down."

which is Cold War mentality at its normal .I can't see Soviets opening fire on an aircraft of the other superpower in 1987 .They did shoot down the Korean airliner but it had penetrated Soviet territory plus the Su-15 had a Mig-23 escort since Russians would expect the humanistic West to care for its people ; there was even an US senator on board .The 747 had no escorts.

but it would be a nice photo opportunity with Migs flying rings around the target . Swedish pilots took pictures of the wounded plane with handheld cameras and for sure Soviets would be delighted to shoot ... Pictures .For the Blackbird was something that really had an impact on Russian aviators.

Mikhail Myagkiy was a Mig-31 pilot . Taking it verbatim from the article

"... the procedures for a succesful intercept were crazy and completely inadequate when considered against the threat posed by the SR-71's spy flights. The speed and the altitude of the American aircraft simply hynotized everyone . Consequently ,each attempted SR-71 interception was considered a top priority ,not only for the fighter aviation but also for the PVO's entire 10th Army...A mistake at any level - by a pilot ,by ground personnel , a command post or a ground vectoring station brought with it the threat of a military tribunal [court martial]."

"The appearance of an SR-71 was always accompanied by nervousness .Everyone began to talk in frenzied voices ,to scurry about ,and react to the situation with excessive emotion."

to see a Blackbird was nearly a religious experience for the Russians . This is what I got so far.

on January 31,1986 he was scrambled and he executed the "aiming run" starting from 16 000m climbing upto 18900 .The IR system picked up the target in 5 seconds .The weather was nice and the Blackbird was contrailing at 22 to 23 000m .He saw it from 60 km and he passed under the SR-71. Maj . Myagkiy has 14 intercepts to his credit .

he started at Mach 2.3 , was airborne for 15 minutes 40 seconds until he got out of afterburner and turned back .He flew for 30 seconds at 15 000m at Mach1.6 to cool down as the temperature could get upto 800 C. He was back at the airbase after a total time of 50 minutes .

check the one line paragraph above . What is the issue here ? We are talking of an aircraft capable of intercepting targets from 28 to 50000m . Surely and officially the Russians haven't been idle in the decade that seperates the service introduction of the Migs. 179 000 feet makes above 54500 m and probably the Americans did improve too .Who knows , I just speculate. I have a simplistic view of things and did learn it in school that energy totals have to be calculated as potential plus kinetic meaning you can convert your speed into altitude , though ı don't think the Blackbird is in the ballistics business , there should be a limit to where it can go.( Since you can't fire a M-21 at everyone coming at you , you may have to go up . Now how is that as speculating?)

coming back to set my feet back on the ground for a brief duration I want to say the '31 got a through engineering .But remember this is just a touch and go. If desired the '31 can probably go faster than a '25 .It should have the strenght , aerodynamics research to delay the adverse effects of high mach flight , control authority etc etc. If the DF-30 turbofans are a hindrance ,GE's F-120 like variable cycle engines are/were within bounds of a possibility for a Russia/Soviet Union either prosperous or feeling endangered enough to work on it .And that would give KJ Lesnick her Mach 3.4 capable Foxbat/Foxhound .

I am not saying it exists .It just could be.If there was a pressing need for it , it would have been done.

having the conviction that something is out there can't be bad . The failing - if there is anything that could termed as such - is more probably in insisting vigourously that can be taken as a flat denial of the fact . Such an assumption on the part of other posters might cause unresponsiveness .I think surely I am not the only person that can dig up that F-15 inlets offer 10% of the effect of the horizontal tails in pitch control in subsonic flight , rising up to 30% supersonically . Though I found nothing about the porous surface , isn't that for providing undisturbed air to the engines ?

and I am the guy who declared on the What if Speculative Modelling Forum that there has been no contact with extra-terrestials in recorded human history , though the possibility remains that they might exist ; I do have a colourful imagination and some amount of sense .
 

r16

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which can really be called insufficient when it comes to serious discussion but as I have described myself as unreliable , it doesn't mean much to me.

ı am not an expert on any particular subject and it shows when my ideas are examined in the light of sources .The water metanol pipes above are for engine cooling according to Mike Spick ; since turbofans are cooler outside compared turbojets , the Mig-31 doesn't have them. I can correct myself when proven wrong.

but my ideas are too originating from sources .The same Alan Dawes article in Air International has it the Mig-31 radar was developed in 1968 . Which is hard to believe as the the aircraft entered service around 1983 .A product of late sixties would serve on many platforms by then so it should be the date of start . Hardly a misprint since Bill Gunston repeatedly gives the date 1959 for the Foxbat radar in his Modern Air Combat page .

ı imagine things , I write them down. Sometimes they are right , sometimes they are wrong but they are always a product of some thinking and more dreaming . Two more posts follow. I had written them earlier and my track record should clearly show that I tend to be honest .
 

r16

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a huge radar to overcome jamming by the targeted plane calls for a big radome ; lots of drag and heating . The canopy is needed to positively identify the target as someone clever enough to build and brave enough to fly to Moscow can have ugly tricks ; drag and heat .( A TV camera and He-111 style raised pilot seating in landing phase might have been possible but the said camera has to be very resilient and when did Russians start to build real good TV equipment ?) It is a simple trick to let go off a decoy that gives higher returns of radar signals -At that speed chaff would have burned off , probably.So to ensure interception IR guidance also needed but the seeker uses a limited amount of coolant ; heat . Electronics dirt simple since if you are buying transistors from Japan how do you know they don't have backdoors build into them that will knock your interceptor fleet just as the intruders arrive? Electronics requiring coolant , vacuum tubes even more ; heat and this time inside the aircraft .Bill Gunston has mentioned the electronics in EF-111A required the capacity of a Spitfire's radiator , the Russian equipment will not need that much but the problem still remains .In Mig 25 this means 1.5 tons of alcohol though some amount is for brakes etc. Fuel to burn . Wings to carry all the weight to altitude . Since burnthrough range might be short enough to allow the target move out of radar's gimbal limits some amount of turning capability up there as there is no way that you will catch it in a tail chase unless you are lucky to have it pass over you in the proper direction .( Beam attack all the way, although reference to gimbal limits seems an exaggeration .) Since your advanced materials choice at the time is limited , your plane is made of steel ; Mother Russia is not rich enough to buy a proper Foxbat made out of titanium which is horribly difficult to work with for starters. Americans up to 90's practically carved a major part of Eagle's engine mounts instead of machining , so it is not a reflection on Russian industrial capacity .("We're scrapping probably 90 percent of the titanium it takes to build these airplanes because of the way the machines cut and drill and shape parts, and we've got to figure out what to do with that," Maj. Gen. Charles Davis the head of the Joint Strike Fighter program office .)And of course by using welded steel your plane doesn't sweat fuel as the SR-71 does .Wings , inlets , the fuselage all add up to the drag . And going faster should increase it many times .It becomes simpler to accept Mach 3.2 is enough .
 

r16

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and to Moscow part is also superflous ; Russians will probably barrage fire nukes if that kind of target is seen. 64 Galosh missiles are to keep the Kremlin safe enough for an hour and the failure of a decapitation strike will most probably ensure the end of human race . Thus was the logic of Cold War . Attrition over the hours or few days at most was the defined goal , knocking out defensive sites to open the airspace for massive conventional or normal aircraft strikes was the threat Russians were aiming to meet . The Red Army was offensive in nature to guard the Soviet state . Russians are avid history readers and they realised long ago that they didn't stand much of a chance in a protracted war started by a surprise Western attack while a succesful Russian surprise would only prolong the bloodbath . The probable cost of war for everybody concerned made it unlikely to happen .

by having the capacity to intercept the reconnaisance /strike complexes , the Foxbat gave confidence to Russian Leadership in trying to reform themselves instead of going the Hitlerite way . The Mig-25 is a Russian success that they have every right to be proud of . So what it has failed to down a single aircraft up to now ? ( Speicher was shot down by an SA-6.)

this post is not necessarily correct in its assesments.
 

r16

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so here it is ; from realistic to absurd , but ı have always taken myself as a honest guy. And this involves no feelings about anyone , my track record in every forum shows my presence is accepted but my claims are not . That is not a problem for me .
 
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I support you man , sometimes you gotta write what you gotta write. Of course it should not be deliberately provocative and oriented towards a particular person.
 

nele

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To:Avatar re: references

Main sources are autobiographies from Valerii Menitsky (My sky life) and Boris Orlov (Notes of test-pilot). Excerpts can be found at www.testpilot.ru and downloaded (Orlov) www.airwar.ru. Also, there are many other great articles and interviews (mainly in Russian).

There is also great forum at www.airwar.ru, where some participants are former "25" and other MiG/Sukhoi pilots.

And it is from former MiG-25 pilots words (MiG-25 vs. SR-71)-the targeting system in MiG-25 contained ballistic information of the R-40 missiles calculated with other spatial parameters of target and launching platform, and did not engage "lock" light until there was a firing solution with viable PK... and it was quite common to get "silent kill" on SR-71...
 

KJ_Lesnick

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r16,

What's the PCC-method (Regarding the water-methanol pipe)? The F-4 can do Mach 3.2? Or was that a special model?
 

sferrin

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KJ_Lesnick said:
r16,

What's the PCC-method (Regarding the water-methanol pipe)? The F-4 can do Mach 3.2? Or was that a special model?

F-4 never went Mach 3.2. There was an F-4X concept with water/methanol injection that would have been able to- in theory. Not be be confused with the Skyburner runs. (There's info on the F-4X on this site somewhere.)
 
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did not engage "lock" light until there was a firing solution with viable PK... and it was quite common to get "silent kill" on SR-71...
do we have a SR-71 intercept thread?

If we don't I guess you can start one , starting by posting your sources, we can discuss the validity of what those sources say.
what do you think?
 
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F-4 never went Mach 3.2. There was an F-4X concept with water/methanol injection that would have been able to- in theory. Not be be confused with the Skyburner runs. (There's info on the F-4X on this site somewhere.)

you mean that Israeli program?
I think I read somewhere, that certain Israeli modified F-4s with newer engines and composites made it past Mach 2.6.
 

nele

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avatar said:
do we have a SR-71 intercept thread?

If we don't I guess you can start one , starting by posting your sources, we can discuss the validity of what those sources say.
what do you think?

I can give You only my hear-say in that case. That would not be nice from my side, being new here.
However, I can give You the link to the tread on that Russian forum

http://www.forumavia.ru/forum/8/3/226545629253379674951138094083_all.shtml?topiccount=466

where they discuss about it-among other things. Note, Alexander Garnaev is former test pilot of MiG buerau 8)
 

KJ_Lesnick

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Oh... Pre-Compressor Cooling, gotcha.

From what I remember MIPCC can add incredible amounts of speed to an aircraft without overheating the engines depending on the exact set-up. I remember seeing a design-proposal for a jet-powered booster that used Pratt & Whitney F-100's with MIPCC, and they claimed to be able to get Mach-5 out of them. (The P&W F-100 is *NOT* a Mach 5 engine!) I don't know for exactly how long MIPCC would effectively keep engine temperatures down (Like: 3-minutes, 5-minutes, 15-minutes, 30-minutes etc)


Kendra J. Lesnick
 

nele

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Ok, this is the translation from www.forumavia.ru , post by member "Slava" (I think one of the moderators there), that was MiG-25 pilot.

Both him and Garnaev look little bored with these repeated questions (M3 and SR-71) ::)

www.forumavia.ru Post from Слава: 25/07/2003 [11:19:34]

/Р-15 близок к прямоточному, и в отличие от других двигателей,с ростом скорости и растет тяга(до известных пределов разумеется)Если мне не изменяет память,у земли тяга-12-14 т,то на Н=20,М=2.35порядка 20т(из тех.описания часть 2-я)Существуют ограничения по отключению форсажа,поэтому надо было ждать пока скорость не упадет до М=2.2 .Если разогнать его до М более 2.6-2.7 дальше скорость нарастает гораздо быстрее и здесь главное не прощелкатью.Набором Н проблему не решить ибо число М только увеличивается,и психологически кажется ,что его не остановить./

T: R-15 is simmilar to ramjet, and unlike other engines, with growth of speed also grows thrust (up to the certain limits, of course). If memory serves me well, at the ground thrust is12-14tonnes, but on Н=20, М=2.35 is around 20tonnes (from „technical description“, part 2) There were restrictions on switching off the afterburners, therefore it was necessary to wait for while until speed drops below М=2.2 . While accelerating to M2.6-2.7 or more, speed grows much more quickly and at that point it is important not to overspeed. Getting at higher altitude does not solve a problem, because Mach number grows and it seems, psychologically, that it will never drop.

/Ресурс планера от скорости не зависит, если только не пошел гофрами( я вообще-то не инженер) Движкам то-же ничего не было, если не перешли ограничений по температуре.Случаев, когда снимали движки из-за превышения скорости М=2.83 я не знаю (если не было превышения ограничений по Т) Лично я сходил разок за ограмичения, но конкретно скорость истинную не определил,где-то3100,3200(было при наведении) М была 3. У других случаи за м=3 были,но не намного.
МИГ-25 был и создан для борьбы в том числе и с SR-71.А в варианте МИГ-25 ПД (с другой станцией БРЛС) это вообще не проблема.Проблема была в другом-В своевременном подъеме истребителя, и в грамотном его наведении , ошибка штурмана наведения стоила невыполнения задания./

T: The airframe fatigue does not depend on speed, unless it caused twisting(???) (I am not an engineer). Nothing would happen to the engines, too, unless temperature limits have not been exceeded. I don't know cases of engine stripping because the speed exceeded М=2.83 (unless temperature limits were exceeded too). I personally went beyond the limits once, but then I had not exceeded particular M3 airspeed (3100-3200kph), where- M was 3. There were other cases for M=3 was exceeded , but not much over it.
MiG-25 was built to fight, and that includes SR-71. And in MiG-25PD verion (with another radar) it was not a problem. The problem was in this-in prompt scramble of the fighter, and in the competence of (GCI) intercept guidance, as the mistake of the (GCI) intercept navigator would cause the failure of the mission.
 

r16

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from the Air International article in '84 or '85 , as far as remember the PCC Phantom was to be cleared for a Vmax of 3.2 and depending on water usage would cruise / take photos at Mach 2.4 at up to 10 minutes . I have seen the linked F-4x topic too and I think one of the primary reasons for its cancellation is that it would give Israel a capacity of intercepting SR-71s . While USA and Israel are undeniably close , it was a capability Washington preferred to deny to friends.

and I don't think I was sniping at anyone ... What is the reason that forces such an assumption ?
 

r16

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by the way I have been mistaken in Foxbat's alcohol load ; it has to be 0.5 ton.

foxhound IR system can spot SR-71 from 120 km.

between 1981 and 1989 there have been 11 SR-71 diversions to Norway.
 

KJ_Lesnick

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nele,

From what I remember, any engine with a properly working inlet at supersonic speed will build more and more thrust the faster it goes. It's called ram-compression...

The Foxbat's engines could produce 20 tons of thrust at altitude and speed? How the hell did they manage that (considering the air is so much thinner up there)!?


r16,

Alcohol load? The MiG-25 used alcohol as part of it's cooling system, I know that. Did the MiG-25 also use pre-compressor cooling as well, like on the MiG-31?


Kendra Lesnick
 

nele

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Hm, the diagram in MiG-25RB manual shows cca. 17T at 11,000m/M2.1... in AB1 (95% thrust).

AB2 regulates automatically according to conditions (above 95%). It rarely does below 11,000m, and from the diagram it seems it does not makes much thrust there. AB2 is the main source of thrust, and RB either accelerates or brakes on thrust input, kinda of speed-unstable (brief from the text).

There are some diagrams with "sea-level adjustment" of thrust, but I don't get those... I might upload them in a couple of days, so some engine geek can analyze them.

A trivia, unrelated; there is spin-description-anti spin procedure in the RB aerodynamic manual, including inverted spin... and it behaves well, too... kinda like doing wheelies in a drag-racer. Of the size of locomotive, I guess ;D
 

r16

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ı think alcohol is/was also used in brakes as the hydrolic medium .As for cooling PCC wise I really don't know .
 

KJ_Lesnick

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AB1 and AB2, is that like an afterburner with twin settings (min, max)? Or some other set-up?
 

r16

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sorry to bring this topic up but ı have mentioned that the F-15 had F-16 like wing-fuselage blending at the initial design , but it was not taken . I have based it on Bill Gunston's words in a book but I have never seen the exact drawings or pictures . I wonder if anybody has them ? Or should this particular post be moved to an F-15 thread ?
 

KJ_Lesnick

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r16,

I just wasn't certain I understood what you wrote exactly.

Regarding the moving of this particular post, I would not mind if this post was moved to an F-15 thread


Kendra Lesnick
 

sferrin

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r16 said:
sorry to bring this topic up but ı have mentioned that the F-15 had F-16 like wing-fuselage blending at the initial design , but it was not taken .

North American's entry did but not the McDonnell Douglas version AFAIK.
 

KJ_Lesnick

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sferrin,

Thank you for clarifying that, I just checked on google and found an image of it.


Kendra Lesnick
 

overscan (PaulMM)

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FX studies are here:

http://www.secretprojects.co.uk/forum/index.php/topic,519.0.html
 

KJ_Lesnick

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nele,

R-15 is simmilar to ramjet, and unlike other engines, with growth of speed also grows thrust (up to the certain limits, of course). If memory serves me well, at the ground thrust is12-14tonnes, but on Н=20, М=2.35 is around 20tonnes (from „technical description“, part 2) There were restrictions on switching off the afterburners, therefore it was necessary to wait for while until speed drops below М=2.2 . While accelerating to M2.6-2.7 or more, speed grows much more quickly and at that point it is important not to overspeed. Getting at higher altitude does not solve a problem, because Mach number grows and it seems, psychologically, that it will never drop.

I thought all engines produce increased thrust in response to increased mach number? I would assume that the Tumansky R-15's thrust increases in an unusually extreme manner in response to an increase in mach number?

I remember reading somewhere that the Tumansky R-15 had some kind of supersonic compressor, although I've never been able to get clarification in terms of exactly what that means -- There actually are multiple types of supersonic compressors

- A compressor which is designed to operate at supersonic-speeds with supersonic airflow straight-through the compressor (at least one compressor-stage): An example of this would include the Lyulka AL-7, which featured supersonic flow through it's first compressor-stage

- A compressor which spins at a range of RPM's in which most of the blade is subsonic (except the tips and such at high-power settings); As the mach-number of the airflow going into the engine reaches around Mach 0.3 to Mach 0.7, the RPM combined with the airflow produces supersonic conditions (the blades are largely if not totally supersonic): Such a set-up I've been told allows more compression to be accomplished per stage, allowing a shorter compressor and improves stall resistance.
An example of such a supersonic-compressor would include among others the Rolls Royce Olympus which powered the Concorde.

I'm honestly not sure exactly which one the the Tumansky R-15 fits into (Is it possible for a jet-engine to fit both criteria?)?


The airframe fatigue does not depend on speed, unless it caused twisting(???) (I am not an engineer).

The MiG-25 had problems with wing-twisting/aileron-reversal problems at certain airspeeds....


KJ Lesnick
 

bagera3005

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it Bern throw its compressors at 3+ mock number an it have wing-twisting/aileron-reversal is a good brid but only at mock 2 unlike sr-71 that's true top is still not public an f-15 an 14 can out maneuver it
 

kengeorge

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Not sure if this will help anyone, but I recently read a book by the author James Barrington called 'Foxbat'. The plot line involves a series of thefts of Mig-25's from various countries,whereupon these aircraft ended up in a certain country not a million miles from South Korea. In the book, it was mentioned that the Mig-25 was obsolete, because it's avionics used valve technology especially it's radar.
The explanation from one of the book's characters was very interesting. The reason they gave was that the Mig-25's primary mission was not to counter the U-2 & SR-71 threat, but as an anti-ballistic missile interceptor!
The Mig-25 would use it's mach 3 dash speed to position it's self near the re entry path of an incoming ballistic missile warhead & shoot it down with it's missiles.
The Mig would survive any resulting EMP burst & not fall out of the sky purely because of its antiquated avionics.
A fascinating idea, which does follow some kind of logic when you think about it.
I look forward to your comments on this & hope I haven't confused you all.
 

KJ_Lesnick

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KingGeorge,

I have reason to doubt that as the MiG-25 and it's Vympel R-40/AA-6 Acrid missiles couldn't keep up with the closure rate of an SR-71, let alone a Ballistic-Missile...

It would seem the MiG-25 was designed for exactly what it was said to be designed for, to take out the A-12, and probably high speed bomber threats we had.


KJ Lesnick
 

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