V-3420 for P-47 variant

[wuzak]

During the war the USAAF requested that Republic fit a P-47 with the (nominally) 2500hp Chrysler IV-2220 V-16 liquid cooled engine.

If you believe some sources, this beast was capable of around 500mph.


Did the Army ever consider the V-3420 as an alternative power-plant for the P-47?

The advantages of the V-3420 over the IV-2220 are:

• Closer to production
• Could mount a cannon firing through the hub (I think - that was an original requirement of the V-3420)
• Shorter, but wider
• Easily configured for contra-props
• Much more power available - 2600hp without pushing by the time the XP-47H flew.

Disadvantages would be

• Heavier - though not by much
• Would probably require two B series turbos rather than one C series turbo

Compared to the R-2800 in the P-47 the V-3420:

• Would have a heavier installation
• Would be more prone to battle damage (the old liquid cooled argument)
• Would be longer
• But would offer much more power

So, could it have been done? Should it have been done?

 

[GregP]

The V-3420 in the P-47. Hhmmmm, let's see.

The Chrysler weighed 2,440 lbs dry while the V-3420 weighed 2,600 lbs dry, so we're seeing another 160 pounds, which means almost nothing. The R-2800 weighed 2,360 lbs dry, so it was in the same ballpark, weight-wise.

Instead of 16,400 lbs typical weight, we'd be looking at 16,680 lbs for takeoff plus cooling system weight. Might make the low 17,000 pound range.

The power level would have risen a bit from 2,600 HP for the V-3420 and it performed better in the B-29 conversion than its normal powerplant did. I see no reason to doubt it would have done the same in the P-47. I'm not much in favor of very complex engines but, in this case, it might have worked out well. I would not care to predict same, but it could be. With contra-props it could have been very much easier to fly and fight, but maybe I am making too much of the torque since the P-47 acquitted itself well in the event.

This one is interesting, and I'd love to try it, but would not care to predict the end result without more information. Still, it seems like a decent suggestion for a trial unit or two for evaluation purposes. It might well have looked similar to the real XP_47H aircraft.

 

[tomo pauk]

The tubo system of the P-47D was proven to handle air needed for 2600 HP, so we should stick with single C series turbo. The sytems in P-47M and -N were capable to cater for 2800 HP.
Any info about the turbo systems used at that big Lockheed fighter?

 

[wuzak]

The XP-58?

Not sure, but according to Joe Baugher the engines were rated to 3000hp.

The XF-11 and XF-12 with 3000-3500hp R-4360s both used two C-series turbochargers per engine.

 

[Shortround6]

Ok lets look at it.

Streamlining compared to the Chrysler is shot. view over the nose? While the R-2800 is as wide, it is a lot shorter.

Cannon through the prop? Maybe, maybe not. Gun has to go behind the engines. re-arrange supercharger and accessories? Gun tube is running within inches of the exhaust manifold.


When do you try and make this thing. Not all "C" series turbos are equal. There were 4 "C" series turbos and the later ones had higher rpm limits and airflow.

The V-3420 was never fully sorted out ( using a single large supercharger for both sides was probably a mistake) and use was delayed while they decided which turbo to use ( development was being done with a different turbo than either either the "B" or "C".).

 

[wuzak]

Streamlining compared to the Chrysler is shot. view over the nose? While the R-2800 is as wide, it is a lot shorter.

One would argue that the view over the nose of a P-47 isn't at all fantastic to start with.

I would also say that the height of the V-3420 is very much less than the R-2800, so that could help with the view over the nose.

Cannon through the prop? Maybe, maybe not. Gun has to go behind the engines. re-arrange supercharger and accessories? Gun tube is running within inches of the exhaust manifold.

I wasn't sure about the cannon through the hub. Just recall that it was a stated design goal.

 

[wuzak]

The V-3420 was never fully sorted out ( using a single large supercharger for both sides was probably a mistake) and use was delayed while they decided which turbo to use ( development was being done with a different turbo than either either the "B" or "C".).

It was also delayed because the AAF couldn't work out if they wanted it or not. It was one of those on again/off again projects.

Using a single supercharger for both sides meant that they had to develop a new supercharger. Using two original superchargers means two gear trains to drive them - may as well have both halves capable of operating independently.

 

[Shortround6]

They had distribution problems, the cylinder banks let alone cylinders were not getting the same amount of fuel/air. Perhaps solvable by a balance tube at the front of the engine?

Operating independently means either counter rotating props or clutches capable of handling 1200-1500hp.