How Radial Engines work

[earl1937]

   I ran across a couple of u-tube video's of WW2 type radial engines which I thought you guys might enjoy seeing.
http://www.youtube.com/watch?v=EyPvpdy4dgg   This is the same engine which is in the F4U series of aircraft. A good explanation of the working parts and etc.

The next video shows how the radial works, when viewed from the front. See if you can figure out which is the "master" cylinder and which are the slaves.
http://www.youtube.com/watch?v=HGKXdYCksAQ

Some may ask, "well, what is the benfit of this info in Aces High?  My answer would be: If you are a aviation nut, the more you learn, the better the pilot you would be, both in RL and AH!

[pembquist]

is that a planetary reduction gear at the front end?

[earl1937]

is that a planetary reduction gear at the front end?

All radial engines had a reduction gearing system in the nose section. The props never turn the same as the RPM, except fixed pitch props, and the only one of those in this game is the Storch.

[bustr]

Why did Great Britain go with the sleeve valve when we were getting good results with poppet valve? Or is that like asking why we drive on different sides of the road?

[Bruv119]

Why did Great Britain go with the sleeve valve when we were getting good results with poppet valve? Or is that like asking why we drive on different sides of the road?

left is the right side !

[Saxman]

left is the right side !

I thought I read somewhere that's biologically due to right eye dominance.

[nrshida]

Why did Great Britain go with the sleeve valve when we were getting good results with poppet valve? Or is that like asking why we drive on different sides of the road?

In England it was mainly Harry Ricardo's work on this is design. The first British tank had one of his sleeve-valve engines in it. We weren't getting good results with poppet valves, they were all plop back then. It's a Betamax / VHS thing. The poppet valves just ended up having more development work and once you reach that certain tipping point other designs, even arguably superior ones, tend to get abandoned.

[Greebo]

One of the reasons for going with sleeve valves before the war was to prevent knocking associated with poppet valves. As it turned out the development of high octane fuels helped cure this problem for conventional engines anyway, but the designers weren't to know this at the time. Sleeve valve engines gave very good performance and were eventually made reliable too. Their main hassle was in mass producing them, a problem that wasn't given sufficient attention in Britain pre-war.

[earl1937]

One of the reasons for going with sleeve valves before the war was to prevent knocking associated with poppet valves. As it turned out the development of high octane fuels helped cure this problem for conventional engines anyway, but the designers weren't to know this at the time. Sleeve valve engines gave very good performance and were eventually made reliable too. Their main hassle was in mass producing them, a problem that wasn't given sufficient attention in Britain pre-war.

One main reason the U.S. engine producers used the valves in their engines was one of "cooling"! They found it was easier to cool the poppet valves and was less a problem with warping filling the insides of  the valves with "sodium". Might be other reasons as well, but that is what I was always told by AF engineering officers. I am not sure, but I think the sleeve type valve had a solid stem, which if the engine over heated just a little, they would warp!

[morfiend]

One main reason the U.S. engine producers used the valves in their engines was one of "cooling"! They found it was easier to cool the poppet valves and was less a problem with warping filling the insides of  the valves with "sodium". Might be other reasons as well, but that is what I was always told by AF engineering officers. I am not sure, but I think the sleeve type valve had a solid stem, which if the engine over heated just a little, they would warp!

  Earl,sleeve valve engines don't have valve stems,they use ports in the sleeve,much like you find on a 2stroke engine. The sleeves usually move up and down but can also rotate,depends on the design and application.

  The sodium not only cools the valve it also reduces the weight over a solid stem,I always wondered why no one made a desmonic drive valve train in aero engines!


   

  PS: maybe they did and I'm just not aware of it!

[MiloMorai]

http://www.youtube.com/watch?v=_vrvep_YOio

Bristol Hercules sleeve valve radial animation

[nrshida]

Especially the exhaust poppet valves are a problem. Actually poppet valves are pretty cack if you look at the gas flow, but you can see how much superficial development has been done if you look at the revs of a modern formula 1 car.

One of Harry Ricardo's motivations for working on the sleeve valve was the upper limit of output he foresaw with the poppet valve. The ports of the sleeve valves make for much easier aspiration. With modern materials you could make a really nice engine. But no one's going to bother now, the end of the piston engine is arguably in sight. 

I've got a very rare book somewhere hereabouts entitled 'Some Unusual Engines'. Took me seven years to track a copy down and cost a lot of money. I can post some of the material if anyone's interested. Went out of print years ago.

[pembquist]

Please post. I'd never seen sleeve valves like the ones in that animation until now.

How well did they seal? I would have thought that the interstitial space would be subject to scorching and loss of effective lubrication. Also does the piston block the valve port on part of its stroke.

[Brooke]

If sleeve valves were better, i think that they'd be used predominantly.

[Wayout]

See if you can figure out which is the "master" cylinder and which are the slaves.

I give up. Which one and why.