OT: Radial Aircraft Engine Cutaway Pics

[stephen thomas]

the only one piece block and head construction engine that I have ever heard of was the Offenhauser race engines.

After Harry Miller went broke & his head machinist Fred Offenhause took over, in some sense in order to get his back pay; in the depths of the depression, he (Fred) built his follow-on business back up starting with Harry's cheapest, simple 4 cylinder boat motor design, to become the might Offenhauser race engine. But before that, all the Millers had integral block & head, and barrel crankcases. More than a few other early race engines were built that way, including the Euro engines that influenced Harry.

smt

 

[EmanuelGoldstein]

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.

There's the danger in universal statements about radials Someone has built a six cylinder, too. And another one has individual camshafts for every cylinder (but it's a cheesy one, shouldn't count.) Seems like round engines are fascinating to a lot of people.

 

[jerholz]

A couple from the Udvar Hazy museum.

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[jermfab]

There is generally a cam ring each, for Ex. & Int. Either machined as one piece, or rigidly assembled.

smt

I see it now:

I circled the two cam-rings. I wish I had taken a bunch more pictures…

All of my experience has been with typical gas engines for cars and motorcycles, if there’s a cam, it runs half crankshaft speed. I didn’t think about the next cylinder in crank rotation needing a valve event as well. The cam-lobes are still only opening the valves every two revolutions of the crank, there’s just a totally different timing trickiness than what I was thinking…

I’ve read the Gordon Jennings book a number of times… even so it took a while to wrap my head around the two-stroke diesel concept. I’ve never taken the time, or had so many examples in front of me, to really consider radial engines before.

I imagine that while the continental radial might make enough power to lose a cylinder and still fly, I cannot imagine they run long without oil-pressure?!? Next time I get the chance I plan on looking closely at the oiling system! I imagine scavenging equally sophisticated to oil delivery.




Be safe



Jeremy

 

[Kevin T]

The OP and topic are the reason I cant go to certain museums with my wife. I get all caught up on stuff like the engine cutaways and can study them for a good long while and she wants to move on to some other area!

 

[adammil1]

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.

Are there companies that can still support making new parts and castings for those engines, or do they tend to fly until critical parts break and then get put on static display? I have to imagine if the patterns are gone reproducing those things may be difficult but with 3D printing maybe it isn't as hard as it used to be?

Or are there enough static display pieces to rob the occasional part if needed?

Pratt and Whitney is an interesting story up here in Connecticut. I am told in one day when the war ended they lost almost all their orders and laid off something like 20-30K employees in the Hartford area (well over 2/3's of the company)!

The other interesting story is how they just barely got into making Jet engines. Towards the end of the war it was clear the radial engine was on its way out but the war department didn't want to distract P&W with making the new engines when what they were making worked, so contracts for Jet engines went to GE and Westinghouse I believe who were already making steam turbines for the power generation. I can't recall the whole story but I gather it was a miracle that Pratt ever caught up, and it was a good thing too as here in Connecticut there's a lot of houses including mine that are at least partially paid for thanks to Pratt.

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[plastikdreams]

When you look into the makings of a radial engine the design breaks down into 3 parts, luck, magic, and skill. The way everything moves and comes together there's no other way to explain it. But radial engines, especially multi row, had cooling issues, some more than others. This is why as soon as turbine technology (jet and propeller) became available the radial engine was dropped like a stone.

Ps: turbine engines have some magic in them, it's just more reliable magic I see the blades and vanes...there's no way someone designed some of these things without some juju on their side, it's freaking impossible.

 

[standardparts]

Pratt and Whitney is an interesting story up here in Connecticut. I am told in one day when the war ended they lost almost all their orders and laid off something like 20-30K employees in the Hartford area (well over 2/3's of the company)!


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In 1980's there was a real fossil still around who was was the Navy rep for R2800 production at one of the subcontracted auto plants. Great stories regarding testing and production of a facility that produced upwards of 18,000 R-2800 engines in less than three years.

Anyway...on VJ day most all workers involved in R2800 production were let go. Workers included a large number of women. Crews were maintained while the gov't decided what to do with all in process engines along with associated equipment. Ultimately unless it was a complete engine ready to go to test everything else was scrapped, much of it going into a pit. Later during the Korean war there was some production and testing of R2800s. In the 1980s one test cell still had an R2800 in place. Ultimately that cell was needed for tool and die storage. The engine and many parts were removed and delivered to the an automotive proving ground as scrap. Someone had a brain and contacted the EAA and they came and removed the engine and parts. The test cells and plant facilities were demolished in the 1990's.

As a side note...there is a vid on youtube that shows an engine plant in Chicago where the shutdown cam so fast than a film being done showing production had to be completed in the shut down, deserted plant....

Engines for Superbombers - YouTube

 

[GregSY]

As for the 6 year old....I know what you mean. When you have a kid in tow, they are the focal point....not the museum, zoo, or whatever you are doing that day. I went to the very nice Pacific War (WWII) museum in Fredericksburg, TX and probably saw 20% of it....spent the rest of the time managing kids.

 

[GregSY]

The Valkyrie....while impressive....was intended to replace the B-52, an exercise that ultimately proved futile. What's impressive is the B-52 has been in service for over 60 years now and is expected to be in use until 2050 (or so). Talk about a lasting design.

 

[stephen thomas]

I imagine that while the continental radial might make enough power to lose a cylinder and still fly, I cannot imagine they run long without oil-pressure?!?

Oops-
If that is referring to my Continental GO300 story, the engine is a flat 6, geared, engine. (not radial)
My anecdote referred to losing critical parts, that went through a cylinder. In my case a complete exhaust valve guide, gradually beat into smaller fragments and expelled into the muffler. Engines, including the one mentioned by somneone else that gradually embedded a valve head into the top of a piston, and (apparently?) kept making power on the rest of the cylinders, often seem tougher than might be imagined. Or the operators luckier.

A lot of people build decent sized model radials. There used to be a smattering of them up to 9 cylinders, among all the other model gas engines, including V-12's, running at Cabin Fever Expo. A few people have built full size engines, including a German guy who built one based on VW cylinders. They can be seen running on you tube. I have not seen mention of any actually being used in an airplane, though. As has been mentioned, Verner makes radials of all sizes in the Czech Republic and they are becoming popular here. IIRC, the heads on the Verners are, or were originally based on, Honda MC singles. Rotac makes geared 9 cylinder radials that had a run of popularity before the Verners. Rotac has a very contentious reputation on media, it seems.

smt

 

[DrHook]

I can tell you that when a 0-300 kicks a rod out of the block, the spinny thing out front doesn't keep doin it's thing for long...

 

[TGTool]

I was doing business with an outfit in Tulsa maybe 20 years ago and got an interesting insight into the engine technology. My contact mentioned work they did on cylinders for an aircraft engine (Continental maybe) in which they received the castings rough machined. They were plated with copper all over, then the copper was machined off the inside so the whole thing could be carburized and finally wind up with only selective carbon addition and hardening. One of those things you'd never learn from inspection until you talk to someone who knows the process.

 

[Clive603]

If anyone wonders why the drum cam system operating several sets of valves per ring was used on poppet valve radials they need only take a look in the gear case of a Bristol sleeve valve radial. Each sleeve needs its own set of drive gears so, as this 14 cylinder 2 row Hercules shows, you tend to end up with something that a watchmaker might find eerily familiar. Just big, very big.



Complete engine sectioned shows how it all goes together



I have a personal soft spot for the Hercules because for most of my childhood the out leg of one of the cross channel air ferry routes passed pretty much straight over our front garden at Crowborough. So the long summer days would be regularly punctuated by the smooth sleeve valve boom of twin Hercules slogging hard to haul a portly, distinctly un-aerodynamic, Bristol Freighter with its load of cars and passengers up to cruise height. Short hauls, hard work and rapid turn round, up to eight flights a day, made for proper engine (and airframe) killing duties. At around 3,000 hour time between overhauls the Hercules was up to the task. The four P&W Twin Wasps on the DC-4 "Carvair" conversions intended as a larger replacement didn't fare so well which probably hastened the demise of the service. I saw very few Carvairs and recall some sounding rather unhappy with their job.

Clive

 

[Cyclotronguy]

DrHook

The spinny thing out front has only one job and that's to keep the pilot cool

 

[plastikdreams]

The Valkyrie....while impressive....was intended to replace the B-52, an exercise that ultimately proved futile. What's impressive is the B-52 has been in service for over 60 years now and is expected to be in use until 2050 (or so). Talk about a lasting design.

The b52 is without a doubt my favorite plane of all time. It's old, ugly, loud, and can lay a hurting of biblical proportions...anything that has dual nuclear capable missile turrets and still carries a shit ton of ordinance inside is ok in my book.

But it's the sound, 8 tf33s makes a lasting impression. Just the sound alone of a flyover can be a deterrent.

 

[EmanuelGoldstein]

Oops-
If that is referring to my Continental GO300 story, the engine is a flat 6, geared, engine. (not radial)

Continental also made radials, I had a W670 from a school auction that was going to go on the front of the van one day ... but luckily, never did It finally got the fan taken off (was used in some sort of tracked vehicle ?) and went back into a home-built aircraft.

 

[Cyclotronguy]

Clive

By any chance do you know how one might get higher res photos of that Bristol Hercules. And in case anyone is curious as to why sleeve valve vs poppet valves. Poppets run hot, to avoid detonation the trend is to run very high octane fuels and rich mixtures. Sleeve valves run much cooler allowing for better thermal efficiency and leaner mixtures. Which is to say lower fuel consumption. There are however trade-off's the sleeve valve engine is tricker to rebuild properly.

 

[moonlight machine]

Radial engines are interesting machines.

Interesting fact, hydrolocking was a big issue in the lower cylinders.

That is why the ground crew turns the propeller backwards 7 blades or so before trying to start the engine, this clears the oil that has leaked past the pistons and rings, turning the engine backwards pushes any oil that threatens a hydro lock event out the exhaust valve. We used to do the same thing just before starting a Indy Car. Back in the day before EFI you could hydro lock the engine with methanol. So before starting put it in 5th and push it backwards a few feet.

 

[EmanuelGoldstein]

We used to do the same thing just before starting a Indy Car. Back in the day before EFI you could hydro lock the engine with methanol. So before starting put it in 5th and push it backwards a few feet.

Dirt drivers must be better trained, they know to turn off the fuel and let the engine run it out before turning off the sparks. You guys and yer fancy starters and fancy gearboxes and fancy clutches ...