Rebuilding the Pratt & Whitney R-4360

[3393RP]

This video is a compilation of photos taken during the rebuild of a R-4360. There's no commentary, but the Vivaldi accompaniment is nice. The size of the engine is striking when compared to the mechanic assembling it. It's freekin' huge.

Before watching this, I had never noticed solder beads on cylinder heads that stabilize the fins. Is this common on other big radials?

There are also photos of a Continental R-975 rebuild in the video.


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[Tom-D]

Before watching this, I had never noticed solder beads on cylinder heads that stabilize the fins. Is this common on other big radials?

YES Wright uses a baked in ceramic strip. Don't know what P & W uses.

OBTW, 4360 was the first engine built by stacking, most of the jets now days are built by stacking one section on top of the pile.

 

[Omalley1537]

Those engines are huge.

When the Boeing museum of flight had the Super Corsair on display, they had a cutaway version. It was amazing to see all the moving parts.

 

[3393RP]

Tom, after studying photographs, I think the material on the 4360 fins is also ceramic, not solder. In the photo below, you can see that part of it missing on one of the cylinders.

I've seen a cutaway of the engine before. I think it was at the New England Air Museum, located at BDL, or maybe the National Museum of the United States Air Force in Dayton. Maybe it was both. Anyway, it's an impressive engineering feat.

The engine has 28 cylinders. Does a cylinder fire every 12.85°, or does more than one cylinder fire simultaneously?

One of the most interesting parts of the engine is the propeller reduction gear assembly. It's wonderfully complex, and must be really stout to transfer that much horsepower. I think the turbosupercharged version produced more than 4,000 HP.

 

[Tom-D]

The engine has 28 cylinders. Does a cylinder fire every 12.85°, or does more than one cylinder fire simultaneously?

No two cylinders fire at the same time. It requires 720 degrees of rotation to fire all cylinders in any 4 stroke engine, so it fires a cylinder at each 25.7 degrees, so you'll have 2 cylinders on power stroke at any given time.
there are two types of ignition one is 4 rows of 7 cylinders each. 4 mags one for each row.
The other is a low tension ignition where there is a coil on each spark plug, and a distributor which only delivers excitation to the coil.(32V) timed by a set of points. 4 distributors 1 for each row.
There is a formula for finding the firing order This is off the top of my head from 60 years ago.
it goes something like this, Start with1, 22, 15, 8, 17, 10, 3, 24, 5, 26, 19, 12, 21, 14, 7, 28, 9, 2, 23, 16, 25, 18, 11, 4, 13, 6, 27, 20.
The formula is a chart.
row A
1357246
row B
5724613
row C
2461357
row D
6135724
See the pattern?
All the odds, then all the evens, start with a different cylinder each row.

My brain just fried, Think I'll go night night. and have a nightmare about changing plugs.

 

[Tom-D]

The prop reduction is a simple planetary gear set. sun Gear is crankshaft, propshaft is the planetary gears, the ring gear is the torque meter, as the crankshaft rotates, the planetary gears walk around inside the ring gear. the more horse power you apply the ring gear wants to turn the opposite direction, it is mounted on a spring set which allows it to move varying a orifice, metering oil pressure to a gauge in the instrument panel.

 

[Tom-D]

I think the turbosupercharged version produced more than 4,000 HP.

No turbo charged, they all had 2 stage superchargers, there were a few that were turbo-compounded, with 3 power recovery turbines, I forget their horse power ratings.

Remember you'd be lucky to get 1000 hours from one of these before it ate its self for lunch.

 

[ktup-flyer]

This is the 4,300hp version.

 

[3393RP]

Tom, I found the turbosupercharged R-4360-51VDT was supposed to power an updated model of the B-36 but it was cancelled, and the engine was also used on an experimental B-50 but there weren't many built.

I think the only engine with three PRTs was the R-3350 used on the Super Constellation and DC-7.

Ktup, thanks for posting that image.

 

[Tom-D]

Tom, I found the turbosupercharged R-4360-51VDT was supposed to power an updated model of the B-36 but it was cancelled, and the engine was also used on an experimental B-50 but there weren't many built.

I think the only engine with three PRTs was the R-3350 used on the Super Constellation and DC-7.

Ktup, thanks for posting that image.

That concept doesn't make much sense, considering they all had 2 stage 2 speed superchargers.
Compounding the 3350 Wright jumped the horse power from 3000 to 3650.
think what that would do for the 4360.