Hi Steve!

I remembered having answered that question before on the “old forum” and I found that the old thread had been transfered and did a copy/paste:

I was borne in the swedish town where Enoch Thulin had his aeroplane factory in the early twentieth century. It so happens that, in our club house at the flying club, we have a LeRhône rotary engine and this is what I know about it.

First of all, engines are stupid. They don´t know if the crankshaft or the crankcase is supposed to turn. It really doesn´t matter and if you start any engine and let it loose on the floor the crankcase will rotate in the opposite direction of the crankshaft.
So if you fix the crankshaft to the airframe the crankcase will rotate.

The crankshaft was hollow to allow the air/fuel/lubricant mixture into the crankcase.
The principle was four stroke with two valves. The exhaust valve is in the top of the cylinder with an outside actuating rod. The inlet valve is an automatic valve in the top of the piston. At the top of the exhaust stroke the exhaust valve closes, when the piston travel down the cylinder an underpressure is created which opens the automatic inlet valve and the mixture is sucked into the cylinder.

This wasn´t very efficient so, soon the inlet valve was moved to the top of the cylinder as well and it too was controlled by an actuating rod. On these engines there were tubes running along the cylinders connecting the crank case with the inlet valve becuse the mixture was still ingested through the crankshaft.

Neither this arrangement was efficient and to allow further developement in terms of HP the rotary design was abandoned.

Hope this helps,
Christer

Janie,
thanks for sharing!

This probably …… :rolleyes: …… put an end to speculating!

Christer

I have actually read a few accounts about pilots “who were there” remembering but remembering wrong. In this particular respect, to mix up what happens behind a Griffon with what happens behind a Merlin is not unheard of.

As I said earlier, I don´t know who Eric “Winkle” Brown is/was and I won´t dismiss anyone without at least the benefit of a doubt:

British carriers had the bridge/island on the starboard side, right?

On which side was the bridge/island on US carriers?

I do know, however, that the co-axial contra rotating propellers on the Seafire 47 made the damned thing go straight, unless the pilot kicked in a bootful of rudder …… :rolleyes: ……

Christer

dhfan,

I thought that too but as I’m not a pilot and can never remember which way the effect works, or work it out, I thought it was brain failure on my part.

It was no brain failure, a propeller which is rotating counter-clockwise, as seen from the cockpit, will make the aircraft torque-roll and yaw to the right – commonly known as swing to the right.

Christer

dhfan,

As Mark12 said, we should be talking about crankshaft rotation.

To be honest, I have never ever seen a crankshaft on an aero engine rotate, a lot of propellers though.

When I view a propeller rotating, then I can deduce;

if epicyclic reduction gearing the crankshaft rotates in the same direction,

if spur reduction gearing it rotates in the opposite direction, unless it is one of these specials for twin engined aircraft.

Strangely, the ‘R’ apears to have conventional rotation (can’t find a picture of a Buzzard) so it was obviously a conscious decision to reverse the Griffon.

The development line was the H engine, the Buzzard, the R engine and the Griffon, which would imply that they had the same direction of rotation.
A closer look at the picture of a S6b reveals a right hand tractor propeller so as You say …… strange ……

Looks like the Sabre had epicyclic reduction too.

If I remember correctly, it was more complicated than that.

The Sabre consisted of two flat twelves on top of eachother. The two “halves” of the engine had separate crankshafts. The power to the reduction gearing was taken off the camshaft drive gears which means that the centrally mounted propeller shaft was driven by four gears mounted around it.
It looks epicyclic but isn´t.

When searching for an answer, I found Rolls-Royce Spitfire which was new to me. There´s a nice video of PS853 in-flight.

Christer

I´ll throw in my two eurocents.

Mark12,

Very intrigueingly it seems, if I am reading this correctly, the propeller opposite rotation was achieved by gearing on the 131 and by crankshaft reversal on the 133!

I doubt the crankshaft reversal on the 133.
According to my information, all righthand tractor Merlins had the idler gear in the reduction gearing.

The Peregrine, developed for the Westland Whirlwind, was planned to come handed. This was the only engine to be completey mirrored, no use of an idler gear in the reduction gearing.
This was abandoned due to prohibitive production costs and all production Whirlwinds had the same type of engine on both sides.

That is the reason that I doubt the crankshaft reversal on the 133.

One possible reason for the Merlin departure from common RR rotation, might be that the PV.12 started as an inverted engine. If they came up with the idea to build it inverted, why not rotating in the opposite direction.

Christer

About rarity, if I recall correctly, some 60 T.20’s were built comparing to 7 T.61’s. Five of the T.61’s were bought by Pakistan and the other 2 by Iraq.
The main difference is the separate canopies on the T.61’s. Rare or not, if I had the chance to buy one (dreaming again) I would convert it a.s.a.p. because it´s so ugly ……

Christer

Thanks Comet!

I´m having difficulties finding local news on the web, not only in my native country Sweden but even moreso in England …… 🙂

Christer