Radial and Rotary engines

[Zak33]

Check these out

RADIAL....the cylinders dont spin..the pistons push the central off-set axle around....



http://www.aviation-history.com/engines/radial.htm

ROTARY.....it ALL SPINS!!!!!

Unreal.....all of it goes round and the prop is bolted to it! Can YOU spell inertia and can you spell torque twist ?



http://www.aviation-history.com/engi...ary-theory.htm

My mind was BLOWN

[Tumble]

Many people remark about the pleasantness of the odor of burnt castor oil. Out in the open where one's exposure is contrasted with other scents, it can be an enjoyable sensation. It is still nice if you are saying, "bye-bye" to the pilot before you go back to your mechanic's tasks. But to sit behind an engine that is spraying you with unburnt - as well as burnt - castor oil is quite another matter after a few hours. The oil is known for its purgative qualities. It would be impossible to expose oneself to such an atmosphere and not experience certain difficulties

LOL.. that paragraph cracked me up good style heheh

[Skii]

Yep - rotary engines had me scratching my head as well
'You mean the WHOLE engine goes around WITH the prop !?!?'

[Zak33]

Originally posted by Skii
Yep - rotary engines had me scratching my head as well
'You mean the WHOLE engine goes around WITH the prop !?!?'

YUP....ALL of it ! Can youimagine the inertia?

First thing I thought to ask the old boy who we were talking to, was how the hell do ya keep the oil in the engine? Its fed into the centre and the spinning engine makes it slide up the bores !

And I have to tell ya.....these things have NO EXHAUST PIPE!!! You can see the top of the cylinder, and the back of the valve is exposed and when the push rod opens the exhaust valve it vents striaght out.....no manifold at all......and its spinning!

Mind boggling!

[Nick]

That old boy also told us how it was a loss oil system. There's no sump, so the oil is kept in a tank and drip fed into the center of the engine. He said that most planes with rotary engines had a valve and flow rate guage so you could control how much oil went in...

Imagine having to force land becuase you'd not run out of fuel but of oil!!!

Another thought that struck was planes with rotary engines must have been damn easy to shoot down. A few good shots into the engine, unbalance the thing and it'd just shake itself apart.

The guy also reckoned that the rotary engined was only designed to solve to the cooling problem. I reckon he's right too. Their fiendishly complex and tricky to manufacture compared with a radial engine, they don't have any power improvements, but they do mean you could completely cowl the thing to improve aerodynamics and therefore performance.

ps. Zak, on the radial, the central axle isn't offset, the big end for the pistons is. (I know its not really a big end, but I mean the thingy which all the pistons are joined to in the middle).

[Private Pyle]

There must be other good reasons for having a rotary engine other than extremely fast banking in one direction

[Nick]

According to all the guys we spoke to, it was essentially just cooling... there were no power improvements and the engine was far more complex. But it did mean you could hae a more aerodynamic plane as the engine could be completely cowled in. The Ju-52 is a good example of a radial engine cooling solution, no cowl at all... the drag on all those cylinders is massive.

[Private Pyle]

Seems like both configurations have there downsides, either drag from the cylinder heads being out in the draft for cooling or inertia.

Suprised anyone really used it when there were plenty of inline engines around.

[Zak33]

Originally posted by Private Pyle
Suprised anyone really used it when there were plenty of inline engines around.

but the engine is so SHORT.....an inline engine takes up loads more room, AND needs water cooling....so radiators somewhere, such as under the wings.

The radial might be very "draggy" but if I was making my first ever plane and had no idea how to do it, cos it was a first ever, BUT had a choice of power plants, the radial would be my first attempt. It justs BOLTS onto the front.....doesn't need to be "integrated" into the nose, just bolted on

Well, thats a basic version of the truth, BUT it does work like that kind-of!

[Private Pyle]

Guess from an engineers point of view sticking it on the front makes sense, rather than having a long the fuselage.

Until someone had the idea of putting jets under the wings

[Zak33]

Hey....a P39 has the engine BEHIND the pilot and a drive shaft running under his bum, with a canon firing THROUGH the centre of the axle.....so they go in all sorts of places.

BUT, when it boils down to it, when aviation was new, cooling was essential, as was easy maintenance, and the power is really quite good for the era

[Private Pyle]

Im trying too picture the wright brothers plane now, think that was at front.