Su-17s vs MiG-27?

[macelena 1,070]

I've been looking a bit into them, not being very knowledgeable on their specifics, and I don't know what difference, if any, they had in terms of their role within Soviet/Warsaw Pact doctrine. They seem to have have more or less equivalent capabilities and seem redundant to a certain extent

[+streakeagle 871]

Soviet development often worked in parallel. The Su-17 was a swing wing variation of the Su-7 while the MiG-23/MiG-27 was a swing wing version of the MiG-21. The Su-7 did not do well as a fighter and proved to be almost as bad as a bomber, so the Su-17/22 series evolved to make it into a good fighter-bomber. The MiG-21 was a far superior fighter to the Su-7 and even the Su-9/11 (which were aerodynamically upscaled equivalents to the MiG-21). It is quite accidental that the MiG-23/27 evolved into the same size/weight class as the Su-17. The attempt to turn the MiG-21 into a multi-role/radar-interceptor comparable to the F-4 led to the MiG-23, but to make the MiG-23 good at the fighter-bomber role, it was "dumbed" back down to the MiG-27.

If there were any differences in their doctrinal roles in Soviet/Warsaw Pact service, it would have been an arbitrary bureaucratic decision. On paper and most likely in reality, the two aircraft are nearly identical in functionality. I am sure the ground and air crews could cite important differences from a maintenance and operational perspective despite the overall similarity in specifications. The MiG-27 shares commonality with the MiG-23, which would be beneficial from a supply/maintenance standpoint. But the MiG-23 had its fair share of problems and the attempts to make it effective at ground attack ultimately required so many changes that it became the MiG-27. Interestingly enough, despite slightly less power, the Su-17 is slightly faster at sea level.

Rivalries and political interests of various factions such as the design bureaus, the Communist party, air force (VVS), and national air defense (PVO) determined the sometimes chaotic development and production paths of the USSR, not unlike the bizarre and wasteful military-industrial complex in the USA. So it is no surprise to me that the Su-17 and MiG-27 ended up functionally being the same aircraft. The F-16 and F/A-18 represents a very similar situation with tremendous overlap in capabilities other than the Hornet being twin-engined, a little heavier, and adapted to operate from aircraft carriers. The YF-17 and YF-16 were literally designed to the same spec with the F/A-18 being a navalized (larger and heavier) variant of the YF-17.

If you study the development of the Su-7/9/11/15 series, there is a pattern of struggling for decades to overcome major design flaws to make an effective fighter/interceptor. By the time Su had hammered out a decent interceptor in the form of the Su-15TM (Flagon-F), the US had developed the "teen" fighters. The response to the new US fighters, the Su-27, finally gave Sukhoi a real design win over Mikoyan-Gurevich. Prior to that, the Su-17/22 was unique in being the only Su jet that was comparable if not better than the competing MiG design. Production numbers might give a clue as to which one was actually liked better: 2,867 Su-17 vs 1,075 MiG-27. But that doesn't include MiG-23B/BN variants.

 

[+Gepard 11,356]

On 2.9.2021 at 3:38 AM, streakeagle said:

The Su-17 was a swing wing variation of the Su-7 while the MiG-23/MiG-27 was a swing wing version of the MiG-21.

 

The first part of your statement is correct. The Su-17 was the successor of the Su-7 and the early versions were very similar in design. Only the swing wing was the difference.

But the MiG-23 had nothing in common with the MiG-21 (only the MiG-23MS used the same radar as the MiG-21bis). The MiG-23 was much bigger. A MiG-21 was a very small plane, similar with the F-104, which was small too. But the MiG-23 had a much larger scale. The radar nose, the engine, the entire fuselage, the gear system. This was completly new on MiG-23.

Tomorrow more. Its to late in Germany now.

[+streakeagle 871]

The MiG-23 was an evolution of ongoing V/STOL work done on the MiG-21. I have the really big MiG-23 book that details the evolution of the MIG-21 that led to the MiG-23 that entered service. I won't waste my time scanning in the photos, but the MiG-23 is a derivative of the MiG-21 just as much as the F/A-18 is a derivative of the F-5. MiG spent many man-hours testing/changing the design to get the final form. Another example is the Su-15: it looks different, but it was an evolution of the Su-9/11. Another example of evolution that included a size change was: F-84F -> RF-84F -> F-105. 

Edited September 5, 2021 by streakeagle

[+streakeagle 871]

I found this photo of a model of the original lift-engine variant. The intakes were moved to the side to fit in the radar, just as was done on the Su-9/11 and the Chinese MiG-21s.

WofRussia04_Mig_23-01.jpg (464×349) (impdb.org)

This is the prototype in flight:

mig23pd-1.jpg (600×296) (bp.blogspot.com)

Early MiG-23 development concepts were based on the Ye-8, which was the MiG-21 with the intake under the nose and a small canard. The Ye-8 variants progressed into the 23-01 variants, which were barely flying before they were canceled in favor of the swing wing redesign that became the MiG-23. So, they didn't start with a blank sheet of paper and build a design around the idea of the swing wing and F-4 style intakes... they started with a MiG-21 variant and kept making changes until they got an acceptable design. The time frame was about: 1963-64 for Ye-8 with lift engine concepts, 1966 for the flying 23-01 prototype, and then about 1969 for several flying MiG-23 prototypes. They spent so much time figuring out what wouldn't work that they were left with almost completely different airplane than the starting point. That is what you can see in the development of the F-105 and F-17 (F/A-18) as well. But that doesn't alter the fact that the design started from an existing aircraft and gradually evolved over time. The Super Hornet is one more case to consider: while it looks very similar to the legacy F/A-18A/C Hornets, it is essentially a new aircraft, yet the first thing the Wiki entry says about it is that it is ultimately a derivative of the F-5. 

Edited September 5, 2021 by streakeagle

[+Gepard 11,356]

MiG-23PD was the designation of the Ye-230 development aircraft line. It had similar wings like the MiG-21, that is true, the gear system was similar. But it was a dead end development line. The same was Ye-8, which based on MiG-21PF. The intended service designation of the Ye-8 was in fact MiG-23. But it had nothing to do with the real MiG-23. The MiG-21PD, which you mentioned, was only a technology demonstrator. It had only fuel for 10 minutes or so and was unable to retract the landing gear.

The MiG-23 based on the Ye-231 development aircraft line, which had not much in common with the MiG-21, beside some electronical equipment.

Back to Su-17 vs MiG-27.

Both planes were developed, because the soviet frontal aviation realized in the 1960th, that there was no dedicated CAS aircraft available. To modify the MiG-17 and Su-7 from fighters into fighter bombers helped not very much. Thatswhy the construction bureaus MiG and Sukhoi got the task to build a fighter bomber plane which should be able to fly CAS missions and tactical nuclear strikes.

Sukhoi took the Su-7 plane and changed the wings in that kind, that the outer wings could swing. This was simple and clever. The development risks were low. The plane was easy to handle for the pilot. Existing weapon stations could be used. Sukhoi decided to add additionaly electronic, like ECM, Laserdesignater etc, as pods on one of the weapon stations. With the last versions this was changed, the Su-17 got the humpback, with enough space for a powerfull electronic package. The latest versions Su-17M4 and Su-22M4 were mighty planes. They were so big and strong, that east german pilots, who after the political change switched from Su-22M4 to Tornado IDS said "In contrast to the "Susi" the "Tony" was a fragile plane!"

The Su-17 was a plane with the major focus on CAS. The MiG-23BN was a little bit different.

The MiG-23BN was smaller than the mighty Susi. Electronical equipment like Laser or ECM were built in internally. The MiG-23BN had thick armour plates on the sides of the cockpit. The Autopilot, the weapon control system and the navigation system were networked. Thatswhy a MiG-23BN was able to follow a flight path along programmed waypoints automatically and was able to fire weapons automatically and was finally able to land automatically. Only for start the pilot was needed, the rest the plane was able to do it alone, without pilots help. Of course, the accuracy of the automatical weapon release was not good enough to hit small targets with conventional weapons, but it was good enough for hitting a target with a 30kt nuclear bomb. And this was the main task for the MiG-23BN. The CAS role was rather secondary and there the MiG-23BN was not really good. The KH-23 missile was more or less crap and without this missile the MiG-23BN was only a dumb iron dropper.

So you can say while the Su-17 was more focused on CAS, the MiG-23BN was more focused on nuclear strike.

The MiG-27 was the attempt to implement modern weapon systems into the MiG-23BN airframe. The electronic was much better, the autopilot, for instance, was not longer dangerous for the pilot of the plane. The air intake system was modified, the engine changed. The plane got the ability to defend itself against air opponents. And so on. The MiG-27 was a much better CAS plane than the MiG-23BN, but finally the latest versions of the Su-17 or Su-22 were the better planes.

Edited September 5, 2021 by Gepard

[macelena 1,070]

I had the gutfeeling that Su-17/20/22s seemed better for CAS and the MiG-23BN/27 looked more suited for interdiction and attacking targets beyond the front, thanks a lot for your replies