Engine Rotation Direction

I don`t know, but probably not. The output of the H Merlin is quoted as 3500 to 4000 hp, which is realistic for Merlin cylinders, 6500hp would be equivalent to a Merlin rated at 3250hp. The highest rating ever actually acheived reliably on the test-beds was around 2600. Do you have any more info on this 100H24?

Pete

Yes it was indeed the Merlin H I was refering to here’s a scan of the cutaway…………….

Once the manufacture of sleeves was sorted out…

Most of us know the story of Bristol sorting out the problems with the sleeves produced by Napier but I stumbled across some figures (that I’m not sure I believe) the other day.

If the five inch bore of the Sabre was scaled up so the bore was one mile in diameter (bear with me :o) the Napier sleeves would be about 100 feet ‘out of round’…

…the Bristol sleeves would be about 2.5 feet!

Frank Halford designed small aero engines for de Havilland and “mad” ones for Napier. Once the manufacture of sleeves was sorted out the Sabre was impressively powerful with virtually identical capacity to the Griffon.

RR did mad too, the Eagle was also H24 and sleeve valve but 10 litres larger in capacity than the Sabre. One that fascinates me was the Crecy V12, sleeve valve, 2 stroke.

http://en.wikipedia.org/wiki/Rolls-Royce_Crecy

Would that be the 100H24 producing 6500hp? apparently never built, just as well really!

I don`t know, but probably not. The output of the H Merlin is quoted as 3500 to 4000 hp, which is realistic for Merlin cylinders, 6500hp would be equivalent to a Merlin rated at 3250hp. The highest rating ever actually acheived reliably on the test-beds was around 2600. Do you have any more info on this 100H24?

Pete

No it isn`t Andy, I think he is referring to the H-Merlin, based on Merlin 100 series components and with vertical cylinders like the Napier Dagger. I am not sure if it was actually built though. Rolls-Royce do have a scale model of it somewhere.

Thanks for the heads-up by the way, I am going to keep an eye on that eBay seller and see what else comes up.
Will you have the Lion runninmg in 2010? (please!)

Pete

Would that be the 100H24 producing 6500hp? apparently never built, just as well really!

Hi Pete, Minimans and all,

I didn’t know about the RR “H” pattern engine !, I honestly thought that RR left all the mad engine’s for Napier to build !

It look’s like that chap has some odd stuff.

I am working on the Lion as much as possible, I have a lot more I can do now the main assembly is done. next time you are passing.

Andy

Hi miniman, the 24 cylinder engine you are refering to was the vulture x-24 which was related to the peregrine.

Andy

No it isn`t Andy, I think he is referring to the H-Merlin, based on Merlin 100 series components and with vertical cylinders like the Napier Dagger. I am not sure if it was actually built though. Rolls-Royce do have a scale model of it somewhere.

Thanks for the heads-up by the way, I am going to keep an eye on that eBay seller and see what else comes up.
Will you have the Lion runninmg in 2010? (please!)

Pete

Hi miniman, the 24 cylinder engine you are refering to was the vulture x-24 which was related to the peregrine.

Andy

For those interested in the inner workings of old aero engines I can highly recomend the large book of sectioned Drawings put out by the Roll-Royce Heritage trust by Lyndon Jones, it contains details of gear set’s and those Quill shafts!!! I got my copy through the aformentioned Rolls-Royce heritage trust.

Until you take a look at these drawings you will never understand just how amazing these Engines are, did you know they made a 24 cylinder Merlin? now there’s complicated wee beastie!! Or the Kestral with sleeve valves………………..

The earlier Sabres were certainly a nightmare, but by the time they got to the Tempest engines they were very reliable and powerful.

Interesting page here on Christer’s site: http://www.hawkertempest.se/NapierSabre1.htm

Wow thanks chaps!
Creaking door. You mention the Napier Sabre’s complexity. My apprentice master at Farnborough worked on them for a short while after the war. He recalls them as being a nightmare to keep working well and said that nobody was either sad or surprized when they were withdrawn! It makes me smile when people sugest say thaey want to get one airworthy again.
Hears a question How many Sabres exist today?

Rgds Cking

A good reason to get one flying again would be the sound. Serviceable engines do exist but the problem has been getting a company willing to sign them off or do overhauls.
At least one company is keen to get into them but nothing has happened for ages.

The list of survivors is here:
http://forum.keypublishing.co.uk/showthread.php?t=87317&highlight=napier+sabre

Pete

Wow thanks chaps!
Creaking door. You mention the Napier Sabre’s complexity. My apprentice master at Farnborough worked on them for a short while after the war. He recalls them as being a nightmare to keep working well and said that nobody was either sad or surprized when they were withdrawn! It makes me smile when people sugest say thaey want to get one airworthy again.
Hears a question How many Sabres exist today?

Rgds Cking

To damp out uneven loads, as one manufacturer says…..

A quill shaft, by definition, is a thin, solid shaft which is strategically designed and carefully machined so that it carries the same torque that a larger shaft would handle by operating at higher stress levels. In carrying torque the quill shaft acts like a torsional spring, twisting along its length.

But some types being hollow, and hence springier, would be a better explanation of the name.

I wonder why they are called “Quill drives”????

Because they are thin and flexible like a quill pen…..at least that’s what I’ve always understood.

One thing they seem to be used a lot for on aircraft engines is to damp-out torsional vibration; a quill shaft will transmit the same torque as a larger–diameter hollow shaft but will twist more readily, evening out instantaneous differences in rotational speed.

I think the Napier Sabre used quill shafts to drive the supercharger; they ran the whole length of the engine inside the hollow sleeve-valve driveshafts!

Even the pistons would have to be redesigned (or reversed :confused:) if an engine was run in the opposite direction, the same magnetos could be used (with the plug leads reversed) but don’t forget the oil and coolant pumps.

Cking is right about accessory quill shafts, but the true meaning is a floating shaft, usually splined at both ends which connects two items together each of which is supported in its own bearings, and this allows for differences in alignment and thermal expansion. The bloody great quill which couples the crankshaft to the reduction gear for example, is not necked down.

I wonder why they are called “Quill drives”???? Designed by Mr Quill?? made by Quill and son’s???
Interesting to hear of a shaft inside the engine called a quill though. My knowledge of the inside of a Merlin is…..well….er…..nil!:D
Perhaps it’s one of those terms that has become *******ized over the years.
Thanks for tha info

Rgds Cking

Hornet 130/131 and 134/135 engines

The Hornet Merlin 130 series engines were indeed handed. This was achieved on all production aircraft by reversing the direction of propeller rotation on the right hand engine, by the use of an additional idler gear.

This extra idler gear made the RH engine nacelle approximately 3/4″ longer than its LH counterpart. In both cases the crank rotated in the same direction.

The additional length of the RH engine was accomodated with an extension to the front edge of the engine nacelle as shown below.

Or a Whirlwind. The entire Peregrine engine was handed. Until recently I understood that was in all cases but according to an article in FlyPast or Aeroplane (I think) in the last couple of years, it was abandoned before the production run was completed.

Only the 1st prototype Whirlwind had handed engines. The 2nd prototype and all production examples had a pair of right-hand rotation engines.
The use of handed engines was abandoned when comparative flight tests with the 1st and 2nd prototypes revealed no appreciable differences in handling or stability.

Niall

The burrs left after grinding are very small, and I think that it is only an issue to get the maximum life from an engine; it may be possible to polish a crankshaft in reverse rotation, but that problem is compounded with RR cranks, because they are hardened with nitriding.

I have tried to find out about the R engine mentioned but I can`t find anything. Don`t forget though that the marinised version would be driving straight from the crank rather than through the reduction gearbox, so to reverse it by using gears would have involved building a reversing box, or did the engines have reversing boxes anyway, as with MTBs, and therefore easily set up to drive the propshafts opposite ways?

Pete

Pete,

Miss England II had twin “R”s, ungeared as you say, R17 running counter-clockwise and R19 running clockwise. They were mounted in the stern with shafts running forward to a gearbox which stepped up the revs and powered a single prop. Frankly I’ve never understood why you would bother with counter-rotating engines is you then drive a single prop. But then again I know nothing about powerboats.

Cheers

Ralph

As for “lefties” and “righties” it is usualy just the very last bit of the gearbox that turns the other way UNLESS you have a P-38, then the whole thing turns in a different direction!. Supposedly you can change one to another but it involves stripping it down into tiny pieces in an engine shop.

Rgds Cking

Or a Whirlwind. The entire Peregrine engine was handed. Until recently I understood that was in all cases but according to an article in FlyPast or Aeroplane (I think) in the last couple of years, it was abandoned before the production run was completed.

A car petrol engine can run (sort of) backwards, if it’s overheated enough, when it’s switched off. It will have no power and run like a pig, but that’s a matter of timing.

Discounting reverse machining, which I’d never heard of – it must be almost at a molecular level – if it was just a case of setting the backlash up in the opposite direction and revising the valve and ignition timing, surely RR wouldn’t have abandoned it so quickly.

Thanks for the quill shaft info, although I already knew what they did. What I didn’t know what was different about them from just any old shaft. Pete’s explained that, (thanks Pete) so now I understand.