10 Incredible Soviet Fighter Aircraft that never entered service

[MigBuster 2,884]

Faced with such a mouth-watering menu of Soviet fighter projects that never entered service, it was almost painful to select a mere ten.

 

 

https://hushkit.net/2016/09/01/10-incredible-soviet-fighter-aircraft-that-never-entered-service/

[Sasin 0]

Apart from the Su-47 none of them are particularly impressing. Especially the Ye-15X series, which are basically horribly oversized MiG-21's. :D

 

To be honest the "mouth-watering" menu of Soviet (Pre-'91) planes are;

 

MiG-29M (Izd. 9-15),

MiG-25M with R-15BF2-300 engines,

Su-27M,

Yak-41,

 

And of course...

 

Lun-class Ekranoplan.

 

I'd like to think that the planes I listed here (and their fates) are pretty interesting.

[+Gepard 11,316]

I miss the Ye-8 here. It was a plane that was nearly as agile as a F-16, but 10 years before the F-16 program started.

[MigBuster 2,884]

The Ye-8 was an improved MiG-21 derivative that was supposed to radically improve on the MiG-21PF interceptor.........hence the larger nose with a bigger radar. The performance improvements were at high altitude supersonic over the MiG-21......there is no comparison with an F-16 - that had totally different design goals.

[JediMaster 451]

Where's the MiG 1.42/44? Too new?

 

Still DOA.

[+Gepard 11,316]

The Ye-8 was an improved MiG-21 derivative that was supposed to radically improve on the MiG-21PF interceptor.........hence the larger nose with a bigger radar. The performance improvements were at high altitude supersonic over the MiG-21......there is no comparison with an F-16 - that had totally different design goals.

 

Ye-8 was twice as agile as the MiG-21PF. Its very close the the first F-16s.

[MigBuster 2,884]

Ye-8 was twice as agile as the MiG-21PF. Its very close the the first F-16s.

 

According to what exactly? there are quite a few reasons why I stated there is no comparison (assuming the German translation of agile is not something totally different.)

 

Who has the performance data to compare......did they compare it against the MiG-29 9.12 and then come to some assumptions?

[Sasin 0]

So. Now I'm interested about Ye-8's and MiG-21PF's specifications.

----

Ye-8;

 

R-21F-300 engine: 46.05 kN dry and 70.55 kN with AF,

7.15 m wing span,

23.13 m² wing area,

 

PLUS!

 

2.16 m span moving canards.

----

MiG-21PF;

 

R-11F2-300 engine: 38.8 kN dry & 60.0 kN with AF,

7.154 m wing span,

23.0 m² wing area,

 

Of course, no canards.

----

I can see why Gepard is making such a seemingly outrageous claim. To describe the situation, I'll be quoting from Aerofax's "MiG-21 Fishbed" book, written by Yefim Gordon and Bill Gunston, pg. 72;

 

Addition of these "destabilizers" increased the lift coefficient by a factor of 2 at Mach 2 and by more than 2 times at Mach 1.5. At Mach 2 at an altitude of 15km the "destabilizers"  enabled maximum sustained turn to be increased from 2.5g to 5.1g, and there was every hope that their use would lead to a dramatically superior fighter.

Of course, I think that this evidence isn't enough, so I'm inviting someone to make calculations of Ye-8's overall wing loading (wings+plus canards), or publish the wing loading calculations of both aircraft from another source.

 

_{(Edit: I wish I had more precise statistics and calculations, the book is all I have for now. I'll look again when I'm feeling OK...)}

Edited October 19, 2016 by Sasin

[MigBuster 2,884]

----

I can see why Gepard is making such a seemingly outrageous claim. To describe the situation, I'll be quoting from Aerofax's "MiG-21 Fishbed" book, written by Yefim Gordon and Bill Gunston, pg. 72;

Of course, I think that this evidence isn't enough, so I'm inviting someone to make calculations of Ye-8's overall wing loading (wings+plus canards), or publish the wing loading calculations of both aircraft from another source.

 

_{(Edit: I wish I had more precise statistics and calculations, the book is all I have for now. I'll look again when I'm feeling OK...)}

 

It is easy to read the YE-8 section in Yefim and completely misunderstand what is written for sure.

 

All the data in there and what I have seen is at high altitude supersonic, including increased L/D and CL over the MiG-21PF so cant really dispute that without better data.

The problem is that there is literally no relationship between this and the rest of its flight envelope especially when we are talking about subsonic lower altitudes.  I don't know what temperature the data was recorded at but most late 50/60s interceptors (F-104, MiG-21PF / Lightning etc) could hit M2 at 49,000ft no problem. However there is not a production F-16 that can even get near M2 at 49Kft outside of a freak day in Siberia..only the downgraded F-16/79 could have even got there.

 

Why do I say that....one massive factor is use of Turbojets that put out a lot more thrust at high altitude high Mach and a requirement as interceptors for high altitude performance......

The 4th Gen jets went with Turbofans which provide far better subsonic performance and fuel economy at lower altitudes where they are expected to spend 95% of their time.....so at M2.0 49Kft even the F-104 and MiG-21 can apparently pull higher G than an F-16.

 

Here is maybe a good example.............. the F-16XL had a 25% higher L/D at supersonic over the F-16A.......but subsonic it totally reversed the F-16A had a 25% better L/D..............so making assumptions based on a few single data points at one part of the envelope only serves to mislead.

[Sasin 0]

It is easy to read the YE-8 section in Yefim and completely misunderstand what is written for sure... <snip> ...So making assumptions based on a few single data points at one part of the envelope only serves to mislead.

Sadly, you're right, but there's also the fact that the first Ye-8 prototype (Ye-8/1) got destroyed because of the overly juiced up engine (which led to severe loss of reliability), and the second one, while having a bit more than a dozen trouble-free flights, had to be abandoned because of the termination of program. So much of the flight data that could be obtained was either not obtained or not published.

 

I'm not shedding tears for the Ye-8 to be honest, because, MiG-23 turned out to be just as competitive, but, it had a really protracted maturity period.

[+Gepard 11,316]

One of the problems of the MiG-21 was the air intake. The plane itself could fly much smaller curves, but this ability was limited by the airflow, which the air intake was able to let through. This caused "pompage" in some flight regimes and in very sharp flown curves. (sorry dont know the right english term, pompage means, that not enough air arrives the engine and the engine sucks so much, that the fuselage is moving like breathing, the thrust is decreasing).

With the bigger air intake of the Ye-8 the problem was solved. Not with the first prototype, which had similar problems with the air intake, so that the design of the air intake was changed a couple of times. With the last design the air intake was able to solve the pompage problem and the engine got enough air at all circumstances. So the Ye-8 was able to outfly the complete possible flight envelope. The canards (destabilisators) additionally helped to increase the agility too.

 

There was everywhere on a russian forum the description of the official Ye-8 test report, with all shortcomings and advantages. I think i have a copy in my archive. I try to find it.

[Sasin 0]

One of the problems of the MiG-21 was the air intake. The plane itself could fly much smaller curves, but this ability was limited by the airflow, which the air intake was able to let through. This caused "pompage" in some flight regimes and in very sharp flown curves. (sorry dont know the right english term, pompage means, that not enough air arrives the engine and the engine sucks so much, that the fuselage is moving like breathing, the thrust is decreasing).

"Engine surge caused by intake air overflow" might be more understandable here.

[MigBuster 2,884]

One of the problems of the MiG-21 was the air intake. The plane itself could fly much smaller curves, but this ability was limited by the airflow, which the air intake was able to let through. This caused "pompage" in some flight regimes and in very sharp flown curves. (sorry dont know the right english term, pompage means, that not enough air arrives the engine and the engine sucks so much, that the fuselage is moving like breathing, the thrust is decreasing).

 

 

Yes one of the reasons the nose mounted air intake on jet fighters followed the TurboJet into history........for optimum airflow it clearly needs to be placed much further back.

 

The Canards on the Ye-8 according to Yefim et al were either mechanically fixed or flowed freely with the airflow so it could only provide increased lift in some parts of the flight envelope over the PF (especially over M1.5 it appears). This is nothing like the Canards you might find on a Eurofighter where they are computer controlled along with all the other high lift devices using FBW to optimise lift and drag over the entire envelope. This is something you could not do at the time of the Ye-8....... but they did improve some basic agility metrics over the PF in some areas of flight due to the increased lift.

 

The MiG-29/Su-27/F-16 also have fixed Canards of a sort..they are blended forebody strakes (sometimes called LERX) they can provide a large increase in lift but you don't get the drag or vibration issues suffered with uncontrolled Canards. When combined with FBW and the high lift LEF/TEF you get a significantly massive performance increase over conventional 3 Gen jets for the areas of flight they are designed for.

[RUSTYMORLEY 162]

Yeah some crappy Soviet stuff there and some interesting ones as well.