Avro 710

I've been reading about V-bombers and interceptors this weekend - mostly but not just in British Secret Projects - and a question has sprung to mind.

In OTL, the British ordered four strategic bombers in the immediate postwar years (Victor and Vulcan as the actual bombers, Valiant as the insurance and Sperrin as the insurance for the insurance). That's fairly unique in RAF history - unlike with the Hurricane and Spitfire they didn't need to order both to get the numbers, one would have been quite sufficient.

At the same time they were also ordering an interceptor to shoot down incoming Soviet nuclear bombers. Interestingly, the specification for the V-bombers was issued on the 7th of January 1947 compared to the 24th of January 1947 for the specification that led to the Javelin. More bizarre still, the Javelin specification called for an aircraft capable of intercepting an enemy at 40,000 ft and no more than 480 kts - right after they've issued a bomber specification for 50,000 ft and a continuous 500 kt cruise.

All of this means that the V-bombers would actually make formidable bomber-interceptors and would handily beat the Javelin specification (indeed, the Vulcan was always claimed to be capable of out-manouvering any aircraft in the world at it's operational height).

Now in OTL, the Javelin requirement was bid for by De Haviland, Gloster, Hawker and Supermarine - the companies bidding on the V-bombers were simply too busy to be interested. However, if they had decided a bit earlier than they did to cut down the amount of insurance they needed (say to two aircraft), an opportunity arises.

Of the OTL bids, the Vickers Valiant was always regarded as pretty low risk, and indeed was in service long before the Victor or Vulcan. So it makes sense to continue with it as per OTL, perhaps discarding the Sperrin completely to save money. Of the others, predicted performance was much the same but the Victor was generally regarded as the more advanced, so it makes sense to drop the Avro Vulcan.

Now comes the interesting bit. As part of the Vulcan development process, Avro built two smaller versions of the Vulcan. The Avro 707 was to test out low-speed handling while the Avro 710 was to explore the high and fast edges of the envelope. The 710 was a half-scale version of the Vulcan, flying on twin Avons and capable of 500 kts at 60,000 ft. While that's a little slower than the Javelin ended up at (although some sources suggest the 710 could reach 0.95 Mach at high altitude, faster than the Javelin ever managed), it's much the same as the Javelin's ancestor was capable of at the time - and the 710 would have room for an enormous AI radar and a lot of fuel. Gloster and Avro were both owned by Hawker Siddeley at the time, incidentally.

Does this sound remotely plausible, and if it had happened what else might have followed? The projected Avon of 1947 was ~6,500 lbs thrust - by the late 1950s we have the RB106 which is designed as a drop-in replacement with over 20,000 lbs thrust. It was cancelled in OTL, but not very much money was ever spent on it - had it continued the Avro 710 would have potentially had truly remarkable performance (and in turn might just have saved the Avro Canada Arrow by both de-risking the design and saving the engine).