No swing-wing aircraft?

[tomo pauk]

(I know this is not ww2, but it is a what-if )
For the sake of discussion, let's assume that aircraft with variable geometry wings don't materialize, apart of those in experimental form. No F-111, MiG-23, B-1 or Tornado as we know them. Any great loss for the military aviation's capability back in cold war and 1990s? How might've look the most prominent 'medium bombtrucks' that Su-24, F-111 and Tornado were historically? Big 'modern' bombers? What instead of F-14? The TSR-2 gets the lease of life?

 

[MIflyer]

Well, we would very probably not have built the F-111 as it was done. Boeing proposed two different aircraft for two different missions for the TFX competion. Not having swing wings would not have enabled the illusion that the same airplane could do two very different missions. Ironically, something like the A-6 probably could have done those two missions as originally envsioned. The USN wanted a missile platform, not a dogfighter, and the USAF found out that supersonic speed at low altitude at night just made it a lot easier for the enemy to find you.

 

[nuuumannn]

Out of interest, the prototype of the Sukhoi Su-24, which has variable geometry wings, did not. It had a cropped delta wing with down turned tips allegedly "a la TSR.2" according to Russian sources. Here it is at Monino 20 years ago.

Sukhoi T6-1 001

 

[tomo pauk]

Out of interest, the prototype of the Sukhoi Su-24, which has variable geometry wings, did not. It had a cropped delta wing with down turned tips allegedly "a la TSR.2" according to Russian sources. Here it is at Monino 20 years ago.

Sukhoi T6-1 001

For the alternative Su-24, the wing similar to the one on Su-15M, or perhaps the crescent-shaped wing? Granted, payload capability will not be as good as on the original Su-24.
In case the swing-wing is all-together discarded, we'd probably see the boundary-layer control - compressed air supplied by engine being blown over the flaps and wings - rise in prominence; same for drooped ailerons. Those techniques were used on the Blackburn Buccaneer, for example.

 

[swampyankee]

Variable sweep wings do offer a combination of good subsonic and supersonic performance, with low-speed performance aided by flaps being more effective on unswept wings. The combination of low aspect ratio and sweep also helps ride quality in low-altitude, high-speed penetration.

BLC would certainly be a viable alternative if take-off and landing performance were the main concerns, but doesn't address the contradictory requirements of subsonic efficiency (loiter) and supersonic performance.

 

[tomo pauk]

Variable sweep wings do offer a combination of good subsonic and supersonic performance, with low-speed performance aided by flaps being more effective on unswept wings. The combination of low aspect ratio and sweep also helps ride quality in low-altitude, high-speed penetration.

BLC would certainly be a viable alternative if take-off and landing performance were the main concerns, but doesn't address the contradictory requirements of subsonic efficiency (loiter) and supersonic performance.

The loiter time was probably, if not certainly, very low on list of priorities when F-111/Su-24/TRS-2/Tornado were being designed. Those were supposed to get in, bomb enemy, and get out. Not the case for MiG-27 and Su-17, granted, although I suppose that either of those two was no better overall than Jaguar with it's tiny wing.
Supersonic performance will still be there with wing shapes, sizes and profiles of the day. Ditto for the ride quality & low gust response. The TSR-2 was a step in that direction - small wing that combined blown flaps for good payload capability and low-speed abilities.

 

[GrauGeist]

With no swing-wing B-1, I'd imagine that the USAF would have either brought the B-58 back in service or turned to the XB-70 for further development.

 

[MIflyer]

In the actual production version of the B-1 finally produced after Carter cancelled the original design, the speed was reduced considerably.

 

[GrauGeist]

In the actual production version of the B-1 finally produced after Carter cancelled the original design, the speed was reduced considerably.

There was a trade-off, actually. They lowered the top speeds in order to reduce it's radar signature: the variable aspect intakes of the B-1A had a considerable signature.
However, the B-1B's subsonic speeds were higher than the B-1A's by about Mach .07

 

[swampyankee]

The loiter time was probably, if not certainly, very low on list of priorities when F-111/Su-24/TRS-2/Tornado were being designed. Those were supposed to get in, bomb enemy, and get out. Not the case for MiG-27 and Su-17, granted, although I suppose that either of those two was no better overall than Jaguar with it's tiny wing.
Supersonic performance will still be there with wing shapes, sizes and profiles of the day. Ditto for the ride quality & low gust response. The TSR-2 was a step in that direction - small wing that combined blown flaps for good payload capability and low-speed abilities.

The other issue is that the center of pressure tends to migrate rearwards as an aircraft exceeds Mach 1, which means that there's a lot of trim drag. The variable sweep wing alleviates that. The other way is to accept negative stability in the subsonic regime, which is part of the reason the F-16 was designed with "relaxed" static stability. Except for a couple of specialized aircraft, like the YF-12A, SR-71, and Concorde, supersonic efficiency was not a driving factor in the design. Even without this some military aircraft could supercruise (i.e., cruise at M>1 without afterburner, iirc, this group included the Grumman F-14 Tomcat, the BAE Lightning, and the F-104)

 

[Admiral Beez]

Perhaps we'd see earlier arrival of the canards.

 

[tomo pauk]

For the Amercains, we might see perhaps A-5 lookalike as a bomber? Another option - delta wing, probably from GD since they have had most extensive experience in that field. Basically the American take on Mirage IV topic.
Canards are indeed interesting add-on that improves things at low speed, even the fixed canards are good.

 

[swampyankee]

Certainly, something like an enlarged A-5 would be an alternative configuration to the F-111. While its linear bomb bay was a virtual complete failure, the aircraft's aerodynamics and overall performance was quite good.

 

[Admiral Beez]

Certainly, something like an enlarged A-5 would be an alternative configuration to the F-111. While its linear bomb bay was a virtual complete failure, the aircraft's aerodynamics and overall performance was quite good.

F-111 was originally intended as an interceptor, so perhaps different variants of the North American F-108 Rapier can do both the F-14 and F-111 roles.

 

[GrauGeist]

The F-106 was the last USAF interceptor in service.
Not only was it one of the fastest single engine air craft of it's type, it was a delta wing, too.

 

[FLYBOYJ]

Great discussion...

A few comments;

As many of you have seen me post, my father in law was the production test pilot on the B-1B. He flew every one at least once from either the left or right seat. He said the B-1B flew like a fighter and posted top speeds didn't mean the aircraft just topped out, it meant that if you kept power levels full open the aircraft would continue to pick up speed until it basically started to self-destruct. He said the same for the F-111 and the F-106, two other aircraft he had several hundred hours in.

A major disadvantage of swing wing aircraft is the complexity of the structure and systems to pivot the wings. IIRC the pivot structure on the B-1B made up 60% of the structural cost of the airframe. Something else to be considered.

Bob is on the right...

 

[tomo pauk]

Great discussion...

A few comments;

As many of you have seen me post, my father in law was the production test pilot on the B-1B. He flew every one at least once from either the left or right seat. He said the B-1B flew like a fighter and posted top speeds didn't mean the aircraft just topped out, it meant that if you kept power levels full open the aircraft would continue to pick up speed until it basically started to self-destruct. He said the same for the F-111 and the F-106, two other aircraft he had several hundred hours in.

A major disadvantage of swing wing aircraft is the complexity of the structure and systems to pivot the wings. IIRC the pivot structure on the B-1B made up 60% of the structural cost of the airframe. Something else to be considered.

Bob is on the right...

Thank you, Joe.

The last paragraph is very interesting. For many airforces, costs of both purchase and maintenance were a real issue. The time needed to design, test and debug was also a factor - one cannot buy time, and it again increases the price of purchase.

So without the VG wing, we'd probably see the alternative MiG-23 introduced a few years earlier, talk 1970 vs. 73? Shape when looking from above probably resembling Mirage F1, or Su-15M minus one engine. The earlier availability, capacity for much more fuel & other payload than MiG-21, as well as capacity for better electronics to be installed probably means more of the 'alt MiG-23s' to be produced at expense of MiG-21 production. Similar fate for the MiG-27 and Su-17?

 

[tomo pauk]

An interesting wing's planform and size was that of the wing on the later EE Lightnings, with a slight 'kink'. As-is, it should've been interesting to see on the alternative MiG-23/27 and Su-17.

 

[Graeme]

IIRC the pivot structure on the B-1B made up 60% of the structural cost of the airframe.

Interesting, especially when you consider authors in the early/mid 70's were predicting 3% of the gross weight.

Edit - sorry Joe, just realised now you were talking about cost.

 

[The Basket]

The MiG-23 had to have better take off and landing characteristics than the MiG-21.

So some interesting ideas could have happened. Lift jets like a Yak or maybe a mini MiG-25? Or maybe a Fishbed but bigger? Or maybe the Su-15 would have been a standard fighter?

Take away the VG and the Flogger ceases to exist. MiG-27 ceases to exist also and the USSR is very short on tactical bombers. May have to invent VG to match the needs.