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Ye-8 to Mig 23?

zen

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I have to come clean first and say I do think the Ye-8 development of the Mig21 was a very attractive design, and also as far as I've read quite a potent one.

Yet sadly for reasons that seem somewhat unclear to me, this design failed to go beyond the prototype and I suspect that has much more to do with Soviet politics and relationships that anything wrong or right with the aircraft.

So what would happen if this was selected for production and perhaps if there is something flawed in the design what would that be and how would it be overcome?
 

stealthflanker

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It would have superior radar compared to MiG-21F/P series as it no longer have constraint on radome. On the history side it would made Soviet the first to deploy and operate Delta canard and Three-surface fighter aircraft. Far before Viggen. Soviet clients might be more interested in this aircraft compared to MiG-21P family. We might see India flying hundreds of these, armed with R-13 and R-23.

The clear and imminent problem to be solved would be providing mature engine for this aircraft. The early production version might have same R-11 engine as the MiG-21F/P family, with later production would go with R-13 and ultimately the R-25.
 
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overscan

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There were a few things that doomed the Ye-8.

First, and most important, the R-21 engine was technically too ambitious, and essentially ended the project mostly on its own. It tested fine on the bench but installed on the Ye-8 proved terribly sensitive. Well, allegedly the first Ye-8 used a non-flight-rated engine, and suffered a catastrophic compressor blade failure.

The Sapfir radar and the associated R-23 missiles also rather outgrew the MiG-21 sized airframe. In fact, the first stage Sapfir-I pulse radar antenna was shrunk enough to fit on the standard MiG-21, producing the MiG-21S, while the second stage Sapfir-II pulse-doppler radar grew in size sufficiently to require a larger design all round.

Ye-8 led instead to MiG-23, powered by the R-27 turbojet which increased power via larger size rather than advanced techology - technically it was just a scaled-up R-13.
 
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zen

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So there are two paths forward here....
1. With a cut down Sapfir I radar and R-11 leading to R-25 as a direct improvementon the Mig21.
2. Scaled up around the R-27 engine and full scale Sapfir-1.
 

dan_inbox

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Besides, the FOD-sucking ventral intake doesn't look very compatible with the rudimentary field conditions of the Soviet Union and its allies.
 

overscan

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Ye-8 led to the MiG-23 (first version). Somewhere between the two lies a viable design.
e8-1.gif
mig23pd-1.gif
 
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overscan

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Regarding FOD, with the nose gear position and nose height I think the ventral intake was acceptable.e8-1.jpge8-2.jpge8-4.jpge8-6.jpg
 
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overscan

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In 1963, the MiG-23 designation appeared again in the GKAT documents and in December of the same year another joint resolution of the government and the CPSU Central Committee appeared. The document prescribed to consider options for the MiG-23 with engines R21F-300 and R27F-300 (takeoff thrust 7200 and 8500 kgf, respectively) and a variable sweep wing.
Unknown MiG [Pride of the Soviet aviation industry]Nikolai Vasilyevich Yakubovich

Interesting to consider that there might have been a smaller VG MiG-23 based on R21F-300.
 
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overscan

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This is a transitional design between Ye-8 and MiG-23. Tail is still MiG-21ish. Delete the dorsal intake, move the intakes back a little.

MiG-23M.PNG
 
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zen

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I think I prefer the ventral inlet.

Though that said the side inlets seem to work well with the larger engine.

Another thought. ....surely they'd have looked at fitting said inlet to the Ye-150 series?
 

Arjen

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If I remember correctly, the dorsal intake was there to serve two lift jets for STO performance. Eventually the MiG-23 had a swing wing as another way to improve take off performance.
Something similar was done to one of the Su-15's prototypes, the T-58VD, which had three lift jets in the centre fuselage.
 
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Antonio

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In the MiG-23PD the centre fuselage lift jets feed from a lifting panel. No dorsal intakes present.

 
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Archibald

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I never quite understood why did North American moved the air intake afterwards ?
 

zen

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Supposedlythe airflow over the bomb recess was too disrupted by the inlet, making release of the weapon dangerous.

Otherwise the F100BI is among the more attractive and potent fighter/attack designs.
 

overscan

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The F-100BI, Ye-8 and P.1121 all used a very similar intake design based on some NASA work. In the Ye-8 case, the intakes could not be mounted on the side due to the use of canards, additionally the path of the air past and below the cockpit on the MiG-21 kind of of lends itself to ventral intakes as the easiest alternative to nosecone.
 

Hood

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I have always liked the looks of the Ye-8 and it was an interesting attempt to move away from the pure delta. As a concept it probably had more potential than the MiG-23PD, the lift-engines adding little additional capability for the additional weight and internal volume restrictions.
There is probably a lively debate to be had on whether what became the MiG-23 in this scenario should have been a canard delta or a variable-geometry design. Probably pros and cons for either.
 
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zen

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Odd too the lack of a twin engined version....
 

Archibald

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I have always liked the looks of the Ye-8 and it was an interesting attempt to move away from the pure delta. As a concept it probably had more potential than the MiG-23PD, the lift-engines adding little additional capability for the additional weight and internal volume restrictions.
There is probably a lively debate to be had on whether what became the MiG-23 in this scenario should have been a canard delta or a variable-geometry design. Probably pros and cons for either.
From a 2019 point of view the MiG-23 and VG were dead ends and failures, while the Viggen and what followed (Grippen, Rafale, Typhoon) were a little more successfull. YET before FBW delta wings had very long takeoff runs while VG was explicitely created for STOL. And since Russian airstrips were pretty rugged, a VG wing made more sense than a delta.
 
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