Rolls Royce Merlin Aero Engine

[FLYING_TRUCKER]

Gentlemen:

Had a little time on my hands so tried to do some research to find out if any World War Two Bombers were ever fitted with Counter Rotating Props or had engines that could turn opposite to each other.

I looked at the Avro Lancaster, the Avro Lincoln which came out at the end of the war but never saw World War Two service from what I read, the Avro Shackleton which had Griffon Engines with Counter Rotating Props and the American built Boeing Washingtons (B29s).

I might be a bit off topic but I did find some interesting information on the fuel injection/carburetor system used on the Griffon Engine on the Avro Shackleton.

The reason I am so curious about these engines is I do not understand why they did not have the engines on the port side turn opposite to the engines on the starboard side of the aircraft or vice versa.
It would have made more sense and made for much easier control of the aircraft on takeoff and landing or if battle damage/engine failure occured.

It is also interesting to note I believe on many light post war twin engine aircraft both engines still turn in the same direction.

I am sure that even on the "C130" four engined Herc the engines all turn the same way.

Now this does not make any sense to me in this day and age and all comments are most welcome.

Cheers...Happy Landings...Doug

[Hagar]

Hi Doug. The P-38 Lightning had counter-rotating engines (except for the version supplied to the RAF). I'm sure there were others but I think the reason this idea wasn't used by the RAF in WWII was a basic matter of supply & maintenance. It would have been far more trouble to keep stocks of not only left & right hand engines but also the props to fit them. I can imagine a situation somewhere at the back of beyond where they had plenty of left-hand engines but only right-hand props.

I read somewhere that the Allison engines used on the Lightning & other US types were designed to rotate either way depending on which way round the crankshaft was fitted. I'm not sure if they could be converted in the field.

PS. I believe they had problems converting the Merlin to run in the opposite direction. It's not just a simple matter of adding an extra cog to the reduction gearbox.

[ozzy72]

I think the PR variants supplied to the RAF had the original engines actually Doug. I seem to recall from reading the Adrian Warburton biography that the reason he liked the P-38 so much for PR stuff was it didn't swing on take-off.

[FLYING_TRUCKER]

Hi Doug:

Thanks for the info, never thought about the P38 Lightning, but with all the technology and engineering science available during World War Two one would have thought they "would" have done that.  
After all they could make a left wing and a right wing, why not a left turning and right turning engine?

Then to continue today still making engines which only turn one way in light twins seems odd to me as well especially when I look at the safety aspect  of it.

I realize that sometimes keeping it simple is better and supply, training and cost are all factors but so is safety as well.

I am sitting here thinking about going down a runway in a fully loaded Lancaster, Halifax or Stirling and loosing an engine just prior to lift off.
Since you are the only pilot, by gosh that would grab your attention wouldn't it?   [smiley=engel017.gif]

Cheers...Happy Landings...Doug

[Hagar]

I think the PR variants supplied to the RAF had the original engines actually Doug. I seem to recall from reading the Adrian Warburton biography that the reason he liked the P-38 so much for PR stuff was it didn't swing on take-off.

I should have said the ones supplied for evaluation purposes in the early days of WWII. The high torque on take-off was one reason it was rejected. The lack of turbochargers was another. http://www.channel4.com/history/microsites/H/history/a-b/battletwo10a.html

PS. It was the RAF that named it Lightning.

[Hagar]

[quote]Hi Doug:

Thanks for the info, never thought about the P38 Lightning, but with all the technology and engineering science available during World War Two one would have thought they "would" have done that.

[Hagar]

http://en.wikipedia.org/wiki/Counter-rotating_propellers

Counter-rotating propellers
From Wikipedia, the free encyclopedia

Counter-rotating propellers, are found on twin-engine, propeller-driven aircraft and have propellers that spin in opposite directions.

Generally, most conventional twin engines spin clockwise on the left and right engine (as viewed from the the pilot seat). Counter-rotating propellers generally spin clockwise on the left engine, and counter-clockwise on the right. The advantage of counter-rotating propellers is to balance out the effects of torque and p-factor, eliminating the problem of the critical engine.

Counter-rotating propellers should not be confused with Contra-rotating propellers.

Some common aircraft with counter-rotating propellers include:

Piper PA-31 Navajo
Piper PA-34 Seneca
Piper PA-39 Twin Comanche
Piper PA-40 Arapaho
Piper PA-44 Seminole
Cessna T303 Crusader
Beech BE-76 Duchess
Lockheed P-38 Lightning
The Wright Flyer

[ozzy72]

There are loads of cases of Lancs having an engine quit on take-off and doing the whole mission on three.

[Hagar]

I suspect it would have been just after take-off. The Lanc was a remarkable aeroplane but I reckon it would take a very skilled pilot to control a heavily loaded 4-engined type if it lost an engine during the actual take-off run. Most RAF bomber pilots didn't have the time to become highly skilled.

[The Ruptured Duck]

I didn't think that fuel injection was invented back then.

[ozzy72]

Aye, mechanical fuel injection. A lot of the German planes such as the 109 had it

[spitfire boy]

Spitfires had 'diaphragms' fitted to their carburettors from a certain mark (not sure which) onwards. This overcame the fuel starvation problem. And the Griffon engine had fuel injection, so the Griffon-engined variants never encountered fuel starvation problems.

Apologies if all this has already been said

[Ivan]

Don't forget Doug that the Meteor spins in the opposite direction to a Merlin (not sure why as tanks aren't really my thing).
A fully servicable Meteor tank engine will cost you 5000 quid.

Why? because you get 5 gears in reverse and one forward if your engine turns the wrong way

The question is of course cost. I know for instance that the Yak (1 or 3 can't remember which) being rebuilt in Russia at the moment is having an Allison lump thrown in. The new run of FW-190s don't have the original type engine either. For authenticity parts are needed....

Reason #2 is that the original Klimov usually has been demilitarized by placing a cocked grenade between the valve heads... You can't remove the cannon from the engine. There is only one left that still has the original engine (and the centerline cannon)

Also there are a few Yak-11s that have been converted to Yak-3s (it's the same plane but whitout a few meters of wingspan and a radial)

I suppose the cost of having counter rotating props on large four engine bombers was out of the question then but when you think about it, I believe it might have saved a lot of aircrew and battle damaged aircraft.

CR props = extra gearbox = power loss + added complexity

Only reason why the NK-12 is the only CR engine still in production is that it doesn't need a gearbox to change the turning direction, it uses a bunch of internal splitters instead... When the thing is off you can turn both props the same direction.

[spitfire boy]

Some late variants of spitfire were fitted with contra-rotating props - but I have a feeling they were post - war.

The supermarine Spiteful was originally intended for contra-rotating props, as well

[ozzy72]

Spitfire we're talking about paired engines rotating in opposite directions not contra-rotating props