Thanks for the update.
Some interesting facts, FROM HERE - http://www.airvectors.net/idx_wmil.html* While the Merlin-powered Twin Mustangs derived from the XP-82 were only used experimentally or as trainers, the USAAF went ahead to production and operational use of derivatives of the Allison-powered XP-82A.
The USAAF knew that the jet fighter was the way of the future, but early jets didn't have the range for long-range escort missions. In February 1946, the USAF ordered 250 Allison-powered "P-82Es" as interim long-range escort fighters. The order was soon changed to 100 P-82Es, plus 150 night-fighter versions of the Twin Mustang, as detailed below. First flight of the P-82E was on 17 February 1947. In 1947, the US Army Air Forces became the US Air Force, and fighters were redesignated with an "F" for "fighter" instead of the archaic "P" for "pursuit". All P-82s became "F-82s" as a result.
Production F-82Es were slow in arriving, the problem being the updated Allison V-1710 engine. The Allison was selected because Packard had to pay Rolls-Royce a $6,000 USD royalty for every V-1650 the company produced. During the war, Rolls Royce had been lenient about license fees, but after the end of the conflict, Britain's economy was in the dumps and the royalty fee skyrocketed. There was also the fact that General Motors, which owned Allison, had a 40% share in NAA. GM had not been happy with the Mustang's switch to Merlin power during the war, but demand for Allisons by other aircraft such as the P-38 Lightning was strong and GM had not been in a position to protest. With the war over, aircraft production took a dive and GM wanted to sell more Allisons. There were few other reasons to use the Allison engine, since even the two-stage supercharged Allison V-1710 was inferior in power-to-weight ratio to the Merlin.
The souped-up Allison engine was also temperamental and unreliable, and Allison couldn't deliver product in quantity. NAA had completed the 100 F-82E airframes by April 1948, but wasn't able to deliver them all for another year due to engine shortages. In service, the Allison-powered F-82Es were marginally slower than the Merlin-powered F-82Bs and the reliability problems persisted. The V-1710 became known as the "Allison time bomb" due to engine failures. Spark plug fouling from backfiring was particularly acute, and spark plugs were often swapped after a single flight.
NAA engineers modified some Allison engines with Merlin components and fixed most of the problems, but Allison took a "not invented here" attitude and insisted on applying their own fixes, which never quite worked. Given the small production run of the Twin Mustang, even the steep license fee Rolls Royce was demanding for the Merlin was a bargain compared to all the troubles the USAF had with the Allisons. Pilots still found the machine pleasant to fly because its performance was so good even when its engines couldn't be run at their top ratings; in fact, they could lose an engine and hardly notice it. The Twin Mustang was also very agile for an aircraft of its size, and was a very stable gun platform. The battery of guns mounted in the center wing section provided highly focused firepower.
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moment when a new Twin Mustang update appears, but I must admit to getting a little misty-eyed when reading about Rivet. My parents had an old cat, who was my favourite, and one day he just never came in for dinner. That was about 18mth ago. We think he found somewhere comfortable and secluded to pass away. BUT I am sending positive feline vibes to the Reilly team for Rivet's sake.
