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OT: Radial Aircraft Engine Cutaway Pics

jermfab

New member
The little guy and I loaded up and headed to Warner Robins, GA. and the museum of aviation located next to the Air Base there.

Unfortunately the nearly 6-year olds attention span had worn thin by the time we got to the final building.

They had close to a dozen cutaways of WWII-era piston engines.

Leaving the pictures I managed to get here in hopes the community gets some enjoyment from them:

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Be safe



Jeremy
 

johnoder

Moderator
All made with pencil and paper (and slide rule) figuring - in enormous quantities

Both the 18 cyl R2800 and the 28 Cyl R 4360 were Pratt & Whitney Aircraft products
 

OlCat

Member
Jeremy; those pictures are wonderful, I’m looking at them on my phone right now. Will have to get on the bigger screen for more in-depth look.
I have always wondered how the valve train works on these engines, hopefully your pictures will help me understand it.
Thanks so much!
Bob
 

GregSY

New member
Those cylinders/head made as one piece are hard to fathom. Especially how they cut the seats.

Once I was shown a cylinder like that from some airplane that had come in for a full rebuild. One of the valves had lost its head in mid-flight. It's not like they could just pull over....the valve head had bounced around in there, getting slammed by the piston each time it came up. The whole thing was a mess of pecks and gouges. Finally, the valve head embedded itself in the top of the piston, edge-wise, and at least it quieted down.
 

Garwood

Active member
Those cylinders/head made as one piece are hard to fathom. Especially how they cut the seats.

Once I was shown a cylinder like that from some airplane that had come in for a full rebuild. One of the valves had lost its head in mid-flight. It's not like they could just pull over....the valve head had bounced around in there, getting slammed by the piston each time it came up. The whole thing was a mess of pecks and gouges. Finally, the valve head embedded itself in the top of the piston, edge-wise, and at least it quieted down.

I repaired a 16V149TI Detroit that had four cylinders like that. Interestingly, 149 Detroits use forged steel pistons so the valve heads had to work pretty hard to stick into them. Before we fixed it, we had to run that engine with it's full rated 1 megawatt load for most of a day. It did fine, couldn't tell anything was wrong except the pyro temps were dead on 4 cylinders.
 

boslab

Active member
Beautiful, thank you these people deserve to be remembered, my dad said to me his dad ( blacksmith in an ironworks) said all the hard work was finished before I was born, I think it’s easier for us than it’s ever been
Mark
 

Vecair

Member
Those cylinders/head made as one piece are hard to fathom. Especially how they cut the seats.

Once I was shown a cylinder like that from some airplane that had come in for a full rebuild. One of the valves had lost its head in mid-flight. It's not like they could just pull over....the valve head had bounced around in there, getting slammed by the piston each time it came up. The whole thing was a mess of pecks and gouges. Finally, the valve head embedded itself in the top of the piston, edge-wise, and at least it quieted down.

The cylinders are screwed onto the heads by a big clocking machine. The heads are aluminum and the cylinders are steel. If you look closely at pic 7 you can see this.
 

GregSY

New member
I don't mean that exact engine, just an airplane engine of some sort. But maybe it was also two piece.
 

plastikdreams

Active member
Those cylinders/head made as one piece are hard to fathom. Especially how they cut the seats.

Once I was shown a cylinder like that from some airplane that had come in for a full rebuild. One of the valves had lost its head in mid-flight. It's not like they could just pull over....the valve head had bounced around in there, getting slammed by the piston each time it came up. The whole thing was a mess of pecks and gouges. Finally, the valve head embedded itself in the top of the piston, edge-wise, and at least it quieted down.

I bet there was a decent pucker factor on that flight
 

jermfab

New member
All made with pencil and paper (and slide rule) figuring - in enormous quantities

Both the 18 cyl R2800 and the 28 Cyl R 4360 were Pratt & Whitney Aircraft products

One of the planes the little dude was most excited to see was the SR-71:
75894c80fb2396ada57b8911d89dc943.jpg


My personal favorite of the slide-rule era.


I have always wondered how the valve train works on these engines, hopefully your pictures will help me understand it.
Thanks so much!
Bob

To be perfectly honest, even looking at them in person it’s DIFFICULT to really tell what is doing what. Granted, the nearly-six-year-old bouncing off the walls didn’t help matters…

Best I could tell, there’s either a cam per cylinder, or that one cam opens exhaust and intake of two adjoining cylinders. I am certain the cams are gear-driven. I’m not sure where the reduction happens though?!? Cams spin 1/2 crank-speed, the gear on the crank appears to be machined into the counterweight. There’s a small gear from that goes into what I assume is cam-drive, not sure where/how the rest of the reduction happens.

I didn’t take too many more non-kid pictures, as there are lots of better pictures out there of the planes that were on display. Beyond the cutaways, I imagine the community will appreciate these as well:

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The B1-B is nearly as impressive as the SR-71, both in scope and capability. About the only plane I can look at longer is the ONE remaining XB-70 Valkyrie. The Valkyrie takes the cake, in my opinion, as the most elegantly brutal piece of engineering the US has ever produced. Another plane designed primarily by slide rule, intended, effectively, to penetrate enemy radar, drop its nuclear payload and fly out the other side before the enemy even got its interceptors in the air…



Be safe




Jeremy
 

plastikdreams

Active member
One of the planes the little dude was most excited to see was the SR-71:
75894c80fb2396ada57b8911d89dc943.jpg


My personal favorite of the slide-rule era.




To be perfectly honest, even looking at them in person it’s DIFFICULT to really tell what is doing what. Granted, the nearly-six-year-old bouncing off the walls didn’t help matters…

Best I could tell, there’s either a cam per cylinder, or that one cam opens exhaust and intake of two adjoining cylinders. I am certain the cams are gear-driven. I’m not sure where the reduction happens though?!? Cams spin 1/2 crank-speed, the gear on the crank appears to be machined into the counterweight. There’s a small gear from that goes into what I assume is cam-drive, not sure where/how the rest of the reduction happens.

I didn’t take too many more non-kid pictures, as there are lots of better pictures out there of the planes that were on display. Beyond the cutaways, I imagine the community will appreciate these as well:

c10a5860500d87222fe872da31c0e7cd.jpg

cd95b96b30f859f07122dd71b7980bf2.jpg

7237a9e31e6c21bbd9ae5d2c1a0e370c.jpg


The B1-B is nearly as impressive as the SR-71, both in scope and capability. About the only plane I can look at longer is the ONE remaining XB-70 Valkyrie. The Valkyrie takes the cake, in my opinion, as the most elegantly brutal piece of engineering the US has ever produced. Another plane designed primarily by slide rule, intended, effectively, to penetrate enemy radar, drop its nuclear payload and fly out the other side before the enemy even got its interceptors in the air…



Be safe




Jeremy

I dunno...the buff is one mean machine, and produces an unforgettable sound.
 

Bill D

Active member
My understanding is each bank of a radial engine has one exhaust and one intake cam that drives each valve in turn. For this reason each bank of cylinders is a odd number of cylinders. Often 5, 7 or 9.
Bill D
 

john.k

Active member
Back in the day when it was legal to scavenge relics,some friends of mine brought back semi loads of WW2 airplane stuff that had been in the bush since the end of the war......dozens of weathered and burnt Wright radial engines .....some of the engines had the effect of a cutaway as fires had melted parts of the heads away exposing valves and guides,and the steel cylinders had corroded and disappeared ,leaving half pistons and rings frozen in place without any support.....They also salvaged a near complete DC2 ,that had belonged to KLM ,who subsequently took legal action against them to reclaim it.
 

EmanuelGoldstein

Active member
Best I could tell, there’s either a cam per cylinder, or that one cam opens exhaust and intake of two adjoining cylinders. I am certain the cams are gear-driven.
The cam is a big ring with lumps on it. It runs half engine speed: as the cam ring rotates one lump will lift a valve every other revolution. The lobes are not per-valve, they lift every valve in turn as the ring rotates. Usually different tracks for intake and for exhaust. (Have to say "usually" with radials because there are so many weird designs, like the rotaries where the crank is stationary and the cylinders spin.)
 

stephen thomas

Active member
The cylinders are screwed onto the heads by a big clocking machine. The heads are aluminum and the cylinders are steel. If you look closely at pic 7 you can see this.

I dunno if P & W were more pre-emptive, but modern cylinder/head assemblies are screwed together before the cylinder base flange is machined to a hex (or whatever) and drilled. So the stud (assembled cylinder/head) "clocking" to the engine case is done last.

Best I could tell, there’s either a cam per cylinder, or that one cam opens exhaust and intake of two adjoining cylinders. I am certain the cams are gear-driven. I’m not sure where the reduction happens though?!? Cams spin 1/2 crank-speed,

There is generally a cam ring each, for Ex. & Int. Either machined as one piece, or rigidly assembled.
There are various methods to gear them, forward or (generally) backwards to crank rotation. Not 1/2 speed. Usually a lot slower than that, since each bump works on each cylinder in succession. So for, say, a 5 cylinder 4 stroke radial, it fires 2.5 cylinders per crank revolution. If there are 2 intake bumps on the cam ring, each can only fire half of that, or 1.25 cylinders per bump, per crank rev. So it's going to take 4 crank revs: 1 cam ring rev with that set up. Designers can (& did) use different numbers of bumps, compelling different ratios. I don't know for sure, but i believe the cams usually run backwards mostly because it is easier, only one additional set of gears between the pinion, and the ring.

Once I was shown a cylinder like that from some airplane that had come in for a full rebuild. One of the valves had lost its head in mid-flight. It's not like they could just pull over....the valve head had bounced around in there, getting slammed by the piston each time it came up. The whole thing was a mess of pecks and gouges. Finally, the valve head embedded itself in the top of the piston, edge-wise, and at least it quieted down.

I've never lost the entire head off a valve (knock on wood).
However, i lost the entire guide around an exhaust valve, once. (Discovered later - in the event we assumed, or maybe chose to believe, it was an advanced intractable case of carb ice or other carburetor malfunction)
Apparently a Continental GO300 makes enough power on 5 out of 6 cylinders, to keep two grown men in the air for an additional 1/2 hour or so, at low altitude over varied terrain. But it was "interesting." The biggest chunks of the guide turned up in the muffler.

smt
 

Bherzog

New member
If you want to know more about aircraft engines, visit the website "Historical Aircraft Engine Society". A fantastic amount of information

Bruce
 
Absolutely astounding and fascinating, the complexity of radial engines.
The story of Frederick Rentschler, the genius behind Pratt & Whitney engines, is well told in the book published, for I believe their 25th anniversary, in 1950, The Pratt & Whitney Aircraft Story.

In 2006 Graham White put together a very in-depth and detailed story of the 4360, from developments, to variations and the machining processes used to create the parts, as well as where the factories were and includes many drawings, diagrams and photos.
I really don't like that R-4360 Pratt & Whitney's Major Miracle was printed in China, though....

He wrote..
"With its unique fore and aft valve locations, the R-4360 required the use of two cam rings per row-five in total. A split gear mounted on the crankshaft transmits power via a train of gears mounted in the main bearing cap and the crankcase section."
patent.. US2426879A - Radial aircraft engine
- Google Patents


Pratt & Whitney was very proud of their R-4360 and made a hardcover sales brochure in the early years of production, with beautiful airbrushed artwork.
Here are a few pictures from it.

Mike
IMG_3599.jpgIMG_3598.jpgIMG_3597.jpgIMG_3596.jpgIMG_3600.jpg
 

OlCat

Member
Mike, thanks for the heads-up on the patent for the PandW. I will check that out.
Greg, the only one piece block and head construction engine that I have ever heard of was the Offenhauser race engines. I believe that they dated back into the 1930’s. Although I am not sure of that timeframe.
The Evergreen museum is a fantastic place to visit, I was truly enamored with it.
Bob
 

garychipmaker

New member
Mike, thanks for the heads-up on the patent for the PandW. I will check that out.
Greg, the only one piece block and head construction engine that I have ever heard of was the Offenhauser race engines. I believe that they dated back into the 1930’s. Although I am not sure of that timeframe.
The Evergreen museum is a fantastic place to visit, I was truly enamored with it.
Bob
Denver Airport had a cutaway of a radial engine. That's where I learned that all radial engines have an odd number of cylinders radialy. Some have more than 1 row of cylinders. An interesting radial engine is a 42 cylinder Russian diesel engine. I think it was rated @ 6000 HP.
 








 
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