Speaking of the Merlin vs. Allison thread

[GRNDP51]

I was just wandering around on Google and came across something I never knew existed.

http://en.m.wikipedia.org/wiki/Allison_V-3420

Considering the weight of the Griffon compared to the weight of this, and considering the horsepower of the two, would planes such as PM benefit with the 3420??? If some of them actually existed to be used, would it be worth it?? I think it's too heavy but hey, can you do some things to an Allison that you can't do to a griffon?? It's fun finding new things

[88SC]

Re: Speaking of the Merlin vs. Allison thread

You were probably unaware of this too:



http://en.m.wikipedia.org/wiki/Boein..._Superfortress

As far as racing goes, there was one unlimited hydroplane that used a 3420, but I don't think it was very successful.

[boomtown]

Re: Speaking of the Merlin vs. Allison thread

I think this powerplant was tried in Unlimited Hydroplanes. Maybe Big Jim can chime in.

[fastpace]

Re: Speaking of the Merlin vs. Allison thread

What a fantastic thread, a lot of well know name's, me I am just an old RC pylon racer that love's Reno and for sure a Mustang lover because I help build them at the Inglewood NAA factory thread

[CJAM427]

Re: Speaking of the Merlin vs. Allison thread

It's actually funny this came up, I was going to post this in a thread itself.

I just visited the P-75 at the Air Force Museum.
A real beauty, too bad it had handling issues.

[AAFO_WSagar]

Re: Speaking of the Merlin vs. Allison thread

Conner, thanks so much for sharing! I see you figgered out a way round the image limits of this board.... you have a bunch of space now but I'm not sure that the software here would do justice to your photos!

Love it when you guys share museum and other stuff, keeps us couch potatoes informed and in touch

Thanks again.

[CJAM427]

Re: Speaking of the Merlin vs. Allison thread

Conner, thanks so much for sharing! I see you figgered out a way round the image limits of this board.... you have a bunch of space now but I'm not sure that the software here would do justice to your photos!

Love it when you guys share museum and other stuff, keeps us couch potatoes informed and in touch

Thanks again.

Thank you Wayne! I appreciate the complement as well!

I'll post some other AF museum air-racing related stuff in another thread as well then.

[ignomini]

Re: Speaking of the Merlin vs. Allison thread

Had no idea there was a P-75 in existence. How cool is that.

I don't think the 3420 was an efficient engine. Probably has too much weight and frontal area to be a candidate for an Unlimited.

Seeing the XB-70 reminds me just how long it's been since my last trip to the AF museum.

[CJAM427]

Re: Speaking of the Merlin vs. Allison thread

Had no idea there was a P-75 in existence. How cool is that.

I don't think the 3420 was an efficient engine. Probably has too much weight and frontal area to be a candidate for an Unlimited.

Seeing the XB-70 reminds me just how long it's been since my last trip to the AF museum.

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I'ts very cool, I didn't know it existed till it was right in my face last week.

Those are cool photos, at the museum's Airpark I presume? I think all of those aircraft are now inside one of the many buildings, and the airpark is full of other treasures.
It'll be cool when the 4th Hangar opens up, we'll all have a much better view of the stuff currently in the R&D hangar, it is packed right now! In order to get this much of the Valkyrie I was up against the doors at 10mm, and still couldn't get the whole thing.

[L.E.D.]

Re: Speaking of the Merlin vs. Allison thread

I'ts very cool, I didn't know it existed till it was right in my face last week.

Those are cool photos, at the museum's Airpark I presume? I think all of those aircraft are now inside one of the many buildings, and the airpark is full of other treasures.
It'll be cool when the 4th Hangar opens up, we'll all have a much better view of the stuff currently in the R&D hangar, it is packed right now! In order to get this much of the Valkyrie I was up against the doors at 10mm, and still couldn't get the whole thing.

I remember my first visit to NMUSAF; the B-70 was still in one of the main hangars. I wandered around until I was foot-sore on the concrete floors, and found a bench to park on for a few. After a minute I realized that next to me was an *enormous* landing gear leg, and that I was under the B-70, and not a normal height ceiling. From that position you can just see the end of the engine inlets - no hope of seeing the nose.

Between that and having parts of the B-36 loom over the WWII and Berlin Airlift exhibits, it was hard to keep a sense of proportion...

[440_Magnum]

Re: Speaking of the Merlin vs. Allison thread

You were probably unaware of this too:

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http://en.m.wikipedia.org/wiki/Boein..._Superfortress

And don't forget this, which IIRC was the reason Allison developed the 3420 at all:

http://en.wikipedia.org/wiki/Lockheed_XP-58_Chain_Lightning

I don't have any analytical data or reason to think this, but it seems to me that "coupled" engines created by in one way or another joining two existing designs never seemed to work out great. Especially for aircraft. The Tank Power Module (5 inline sixes coupled to a common flywheel) used in some versions of the Sherman Tank, but that's definitely the exception more than the rule.

[W J Pearce]

Re: Speaking of the Merlin vs. Allison thread

And don't forget this, which IIRC was the reason Allison developed the 3420 at all:

http://en.wikipedia.org/wiki/Lockheed_XP-58_Chain_Lightning

I don't have any analytical data or reason to think this, but it seems to me that "coupled" engines created by in one way or another joining two existing designs never seemed to work out great. Especially for aircraft. The Tank Power Module (5 inline sixes coupled to a common flywheel) used in some versions of the Sherman Tank, but that's definitely the exception more than the rule.

Actually, the V-3420 started out life as the X-3420 (one crankshaft) and morphed into the V-3420 (two crankshafts) to lessen developmental time and issues. The AAC was looking for large engines for its long-range bomber "Project D" initiative. Project D resulted in the XBLR-2 (XB-19). The engines were not ready by the time the XB-19 was (1941), so it was fitted with R-3350s—the first aircraft so equipped (I think). V-3420s were installed on the XB-19 in 1943 and stayed on till the aircraft was scrapped in 1949. Development of the V-3420 was well along before XP-58 development began in 1940.

The most successful "coupled" engine that I can think of is the Armstrong Siddeley Double Mamba used on the Fairey Gannett. Of course, that was two engines driving separate propellers on a common axis, so one could argue that they were not truly coupled. But then the engines of the five-bank Chrysler A57 were all separate, just driving a common flywheel. A failed engine would decouple, leaving the other four to produce power.

I think for most coupled engines, better ideas came along that made them obsolete or redundant. The V-3420 did not cause the failure of the XB-19, XB-39, XP-58, or XP-75—none of them represented a significant jump to justify their continued development.

[440_Magnum]

Re: Speaking of the Merlin vs. Allison thread

Actually, the V-3420 started out life as the X-3420 (one crankshaft) and morphed into the V-3420 (two crankshafts) to lessen developmental time and issues. The AAC was looking for large engines for its long-range bomber "Project D" initiative. Project D resulted in the XBLR-2 (XB-19). The engines were not ready by the time the XB-19 was (1941), so it was fitted with R-3350s—the first aircraft so equipped (I think). V-3420s were installed on the XB-19 in 1943 and stayed on till the aircraft was scrapped in 1949. Development of the V-3420 was well along before XP-58 development began in 1940.

The most successful "coupled" engine that I can think of is the Armstrong Siddeley Double Mamba used on the Fairey Gannett. Of course, that was two engines driving separate propellers on a common axis, so one could argue that they were not truly coupled. But then the engines of the five-bank Chrysler A57 were all separate, just driving a common flywheel. A failed engine would decouple, leaving the other four to produce power.

I think for most coupled engines, better ideas came along that made them obsolete or redundant. The V-3420 did not cause the failure of the XB-19, XB-39, XP-58, or XP-75—none of them represented a significant jump to justify their continued development.

Cool, I definitely didn't know any of the pre-history of the V-3420. Also agree on the "obsolete or redundant" part. Coupled designs were usually rush jobs to get *something* ready, whereas clean-sheet designs had fewer compromises. Another issue with the fact that the 3420 didn't go anywhere is that it came along just at the time turbines were taking over.

[88SC]

Re: Speaking of the Merlin vs. Allison thread

I suppose nearly all surviving V-3420s are in museums, but a few odd - and large - engines have come out of the woodwork as display runners (thanks, YouTube!). The '3420 is one I'd love to see this way.

[IcePaq]

Re: Speaking of the Merlin vs. Allison thread

He177 went into production and into service with the DB610 which was a coupled engine.

It's two DB605s with a common crankcase.