Why I dislike IL-2 games..

[Soviet Ace]

Originally Posted by Robotic Pope

A P-51B/C/D with an Allison engine? Ive never seen one. I'd need a photo to believe that one.

I'm sure you are right about the weight though, that armour plate behind the pilot alone must weigh a ton.

I'm pretty sure, that if you've ever seen a P-51 flying today, it's powered by an Allison... similar (if not the same) to the Allison that powers the Yak-3s of today.

[Robotic Pope]

Originally Posted by Soviet Ace

I'm pretty sure, that if you've ever seen a P-51 flying today, it's powered by an Allison... similar (if not the same) to the Allison that powers the Yak-3s of today.

Well I know the Allison engine needs an air intake above the engine as you can see on this Yak3 and P-51A. I have never seen a P-51D with this intake. Find me a photo of this, only then will I believe it. I can't find any info on the internet of a P-51D ever being "downgraded" in this way either. I'll add that all the P-51D's that I have heard have clearly sounded like Merlins.

[David603]

Originally Posted by Robotic Pope

Well I know the Allison engine needs an air intake above the engine as you can see on this Yak3 and P-51A. I have never seen a P-51D with this intake. Find me a photo of this, only then will I believe it. I can't find any info on the internet of a P-51D ever being "downgraded" in this way either. I'll add that all the P-51D's that I have heard have clearly sounded like Merlins.

This is one of the Spitfire replicas powered by an Allison V-1710, and as you can see, there is no air intake above the engine.

I'll try to find a picture of an Allison engined P51D for you.

[Soviet Ace]

I believe the P-51D at Wanaka in New Zealand, is Allison powered.

[Robotic Pope]

Well there you go. I learned something new lol.

Did a bit of searching and reading. Can't find any mention on why the allison engine suddenly didn't need to have then airscoop on top rather than underneith the engine. It seems to me to be part of the modification that gave the allison a two stage supercharger though. I now know that most the Twin Mustangs went back to using Allisons (even though they were weaker) for political reasons. I expect these fake engined Mustangs are from old F-82's and are all in the US then and why Ive never come across one.

One thing I can't understand. I still count 6 exausts in the photos?

Production F-82Es were slow in arriving. The problem was 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.

The F-82Es were externally indistinguishable from the F-82As except for minor details. One of the giveaways was the engine exhaust stacks. On the Merlin-powered aircraft, there were six exhaust stacks on each side. On the Allison-powered aircraft, there were duplicate exhaust stacks for each cylinder, for a total of 12 exhaust stacks on each side.

[Robotic Pope]

Haha found it. I was right. Page 13 http://www.enginehistory.org/Convent...ingAllison.pdf

The post war, two stage supercharged allison engine doesn't have a carburetor and so doesn't need the air intake. Well that was fun detective work, gave me something to do while watching Le Mans 24h lol

[Balderz002]

Why I dislike IL-2 games..

Because I just got beaten by some bloke flying an A-20 on a realistic dogfight with my useless ass sat in an La-5FN.............. boo hoo. He beat me 5-4.......

[David603]

Originally Posted by Robotic Pope

Well there you go. I learned something new lol.

Did a bit of searching and reading. Can't find any mention on why the allison engine suddenly didn't need to have then airscoop on top rather than underneith the engine. It seems to me to be part of the modification that gave the allison a two stage supercharger though. I now know that most the Twin Mustangs went back to using Allisons (even though they were weaker) for political reasons. I expect these fake engined Mustangs are from old F-82's and are all in the US then and why Ive never come across one.

One thing I can't understand. I still count 6 exausts in the photos?

Perhaps the exhausts from the Merlin are still being used? It should be possible, since both engines are V12s of a similar configuration. It would also make the V-1710 sound more like a Merlin.

Something else I found out about civilian Mustangs is that removing the military equipment (guns, armor, surplus fuel tanks and WWII vintage radio equipment) shaves off around 2,500 lbs from the Mustangs weight, which is roughly a quarter of the loaded weight of a wartime P51D. If the guys who made the Flight 1 P51 for FSX used one of these Mustangs for their flight characteristics, then no wonder it flies so well

[Soviet Ace]

Originally Posted by David603

Perhaps the exhausts from the Merlin are still being used? It should be possible, since both engines are V12s of a similar configuration. It would also make the V-1710 sound more like a Merlin.

Something else I found out about civilian Mustangs is that removing the military equipment (guns, armor, surplus fuel tanks and WWII vintage radio equipment) shaves off around 2,500 lbs from the Mustangs weight, which is roughly a quarter of the loaded weight of a wartime P51D. If the guys who made the Flight 1 P51 for FSX used one of these Mustangs for their flight characteristics, then no wonder it flies so well

For randomness, I still stand that my Yak-3 could chew up your lovely Griffon powered Spitfire any day.