Talk:Republic XF-103

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Is the tag "citation needed" by the text "which would have yielded spectacular acceleration and climb performance" really needed?

Any aircraft with a thrust/weight ratio of almost 1 would have had a spectacular performance for a plane from the 50's (The F-104's was around 0.75)

Diego bf109 (talk) 18:56, 2 February 2008 (UTC)

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Took out a sentence that said something along the lines of "It is not clear why the engine development was a problem, since the engines worked fine in Britain and entered service on the Avro Vulcan". The engines the Vulcan used were Bristol Olympus engines, not the Wright J67s the XF-103 was to have used, and I didn't want the two engines to be confused.

The J67 was indeed based on the Olympus, although I'm not sure to what degree. I've seen various sources with claims ranging from simply "based on" to saying that the J67 was a simple licensed copy. In any event, I'm not sure why Wright was unable to complete the J67, but I didn't want that engine (which didn't work) confused with the Bristol Olympus (which did, rather well).

Every reference I have states the J67 was a directly licensed copy. Thus the question about what went wrong. Maury 19:22, 6 March 2007 (UTC)

Maury, regarding the J-67, did it encounter any production delays in England?... For the time being, I re-wrote the article saying it was a liscence-built derivative of the Bristol Olympus.

AV Kent

Well that's what makes it all so interesting (IMHO). The Olympus went right through its development and test periods and entered service in 1953 -- while the F-103 was still under design. I don't recall any complaints about the engine at any point in its long history. It's really not at all obvious what happened when Wright took it. Lots of other designs had selected the J-67 as well BTW, they all ended up looking for other engines or just being killed. Quite odd! Maury 19:17, 13 April 2007 (UTC)

I hope the following goes some way to explainig why there were engine development problems. The Bristol Olympus 101 did indeed enter service in Vulcan bombers in the early 50's. At the time it had a thrust of 9800lbs and was not reheated (it was later developed to produce 20000lbs as the RR Olympus 301, also in the Vulcan). Curtiss Wrights J67W3 was intended to produce 15000lbs dry and up to 30000lbs when operated as a ramjet. To get to speeds at which the ramjet could operate it also had to have a reheat section. All this in 1954. It was not until the mid 60s that the British Olympus engine operated succesfully with reheat (for Concorde, first flight 1969, as the RR Olympus 593) and no attempts AFAIK were made to ramjet it. The Bristol engine was very reliable but it also had a long history of development to increase the available thrust as evidenced by the type numbers. So the J67W3 was a derivative, not a copy, of the Olympus. It would have been licenced to allow the development of the engine (intellectual property rights etc). Essentially the J67W3 engine concept was way ahead of its time and much too ambitious for the technology of the day. Efforts were made to achieve the required thrust levels by redesigning the reheat/ramjet assembly which gained its own engine designation of XRJ-55 whilst the engine became YJ67 and still unable to achieve the specified thrust. If I've read my sources right the engine was cancelled before te airframe Kitbag 23:46, 16 May 2007 (UTC)

Thanks for the insights Kitbag! Do you know if the J67 was significantly larger than the original, or featured a different number of stages? I'd really like a book on this, if you can suggest one. Maury 12:24, 6 July 2007 (UTC)

Speed claims

The designed expectations for near-hypersonic speed (Mach 5) seem a bit off, given the heating problems likely at that speed. Is there any referenceable statement that explains that the XF-103 would never reach those speeds even if it had the thrust, or was it actually likely to be capable of flying that fast? 166.137.210.44 (talk) 15:42, 14 January 2013 (UTC)

The expectations were for a Mach 3 interceptor (1,724 knots) between 45,000-70,000 feet in altitude. No idea where the Mach 5 figure came from, but clearly its been listed like that for a long time. Dangerousbuzz934 (talk) 22:18, 3 May 2021 (UTC)

Huh?

This article states: "Mach 3 performance in the 1950s was very difficult to achieve." It still is - how many mach 3 aircraft are there running around today (or have there ever been)? — Preceding unsigned comment added by 192.158.48.14 (talk) 12:13, 24 April 2015 (UTC)

It's not difficult to achieve now so much as it's prohibitively expensive to build and operate. We certainly know how to do it, which is what "achieves" means in this context. BilCat (talk) 20:44, 1 September 2022 (UTC)