Simviation Forum - Rolls Royce Merlin Aero Engine

Reply #15 - Nov 5^th, 2006 at 10:58am

Flying Trucker Ex Member

Gentlemen:

So what year, what aircraft and what was the first true fuel injected engine that entered RAF service?

Cheers...Happy Landings...Doug

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Reply #16 - Nov 5^th, 2006 at 11:15am

ozzy72 Offline
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Probably a late model Spitfire like the 21 or one of the Griffon engined Seafires at a guess. I'll have to look into it however...
Of course this would be mechanical fuel injection!

There are two types of aeroplane, Spitfires and everything else that wishes it was a Spitfire!

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Reply #17 - Nov 5^th, 2006 at 11:15am

Hagar Offline
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Only a guess but I suspect it was the RR Welland fitted to the Gloster Meteor F.1. Entered service with No 616 Sqdn in May 1944. http://www.enginehistory.org/r-r_w2b.htm

PS. Of course, most rotary engines have no carburettor so they could be said to be fuel-injected.

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Reply #18 - Nov 5^th, 2006 at 12:05pm

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Were the Napier engines carbs as well then? And the Bristol radials too I presume.

Edit: As the Napier Sabre and the RR Vulture engines had their cylinders in a H and X formation respectively, surely that meant that half the cylinders were upsidedown. And carbs don't work all that well upsidedown, so wouldn't they have been fuel injected?

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Reply #19 - Nov 5^th, 2006 at 12:15pm

Hagar Offline
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Quote:

Were the Napier engines carbs as well then? And the Bristol radials too I presume.

Indeed. From what I can make out supercharged variants used the carb injected systems like the later Merlins. Napier Sabre was fitted with the Hobson injection-type carburettor developed during WWI. http://www.localhistory.scit.wlv.ac.uk/Museum/Transport/planes/hobsons/hobson01....

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Reply #20 - Nov 5^th, 2006 at 1:20pm

Hagar Offline
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Quote:

Edit: As the Napier Sabre and the RR Vulture engines had their cylinders in a H and X formation respectively, surely that meant that half the cylinders were upsidedown. And carbs don't work all that well upsidedown, so wouldn't they have been fuel injected?

Just noticed your edit. The cylinder layout has no effect on the carburettor. The good old 'Dripsy' Major engines in my Tiger Moths have inverted cylinders & run quite happily on a conventional carburettor which is mounted the right way up.

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Reply #21 - Nov 6^th, 2006 at 7:27am

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Quote:

Probably a late model Spitfire like the 21 or one of the Griffon engined Seafires at a guess. I'll have to look into it however...
Of course this would be mechanical fuel injection!

Griffon 62 (Mk21 and 46) had a Rolls Royce fuel injection system as did the 88 (MkXIV? 21 and 47), the 89 (Mk22) and all thereafter (mostly Mk21 and 46/47). Everything else seems to have an injection carburettor of some kind, mostly a Bendix-Stromburg.
Rolls Royce claimed that the carburettor was better than direct fuel injection because of the drop in temperature caused by the air passing the venturi in the carburettor, thus giving better combustion, or something like that. I’ll leave it up to you technical folk to give the proper explanation on that one. Wink

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Reply #22 - Nov 6^th, 2006 at 7:48am

Hagar Offline
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Quote:

Griffon 62 (Mk21 and 46) had a Rolls Royce fuel injection system as did the 88 (MkXIV? 21 and 47), the 89 (Mk22) and all thereafter (mostly Mk21 and 46/47). Everything else seems to have an injection carburettor of some kind, mostly a Bendix-Stromburg.

Thanks for clearing that one up.

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Reply #23 - Nov 6^th, 2006 at 5:13pm

Flying Trucker Ex Member

Interesting reply's folks.

I would think the Allied aircraft operating in the Pacific Theater of operations would really welcome the fuel injected engine because of the type of weather they flew in.

I am not up on military aircraft or commercial jets to much but I would think most of the aircraft operated by Japan in the Pacific Theater were probably fuel injected but please correct me if I am wrong.

The last "Dak" Douglas DC3, C47 we lost in the Royal Canadian Air Force was due to carburetor icing and spun in on a Search and Rescue mission taking all the crews lives.

I picked up carburetor icing on the DC3s several times, always when training a new pilot and they learned real quick how fast they could run out of rudder, how heavy that rudder was and how quick that old bitch would roll. Shocked

"(not that I ever let it get that far)" Roll Eyes

Oh the days of flying the aircraft with "carburetor heat", the proper use of "RPM" and "Manifold Pressure", a good Flight Engineer are nearly done.
A good co-ordinated crew always had something to do.

AND:

Then some dam fool put a suck and blow thing on an aircraft and left off the props. Sad

Took all the fun out of flying they did. Tongue

Okay will stop rambling on and try to keep on topic.

Cheers...Happy Landings...Doug

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Reply #24 - Nov 6^th, 2006 at 6:29pm

Hagar Offline
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Quote:

I am not up on military aircraft or commercial jets to much but I would think most of the aircraft operated by Japan in the Pacific Theater were probably fuel injected but please correct me if I am wrong.

Interesting. You keep asking about things I've never even thought of. Wink

I found a detailed Design Analysis of the Zeke 32 (Hamp) aka Misubishi A6M3 Zero here. http://rwebs.net/avhistory/history/Zeke32.htm
This was fitted with the Nakajima NK1F Sakae 21 also used on the A6M5 & other Japanese types.
Quote:

The Sakae 21 is a 14-cylinder, two row radial aircooled engine developing 1,020 hp. at 2,600 rpm. at 6,400 ft., turning a 10 ft. 3-in, diameter constant speed propeller which is very, very similar to Hamilton Standard design. As installed in Zeke 32 the engine has a down-draft carburetor and a two-speed blower in place of the older single speed. The installation has necessitated moving the. firewall aft eight in. and changing the cowling to put the air intake at the top.

This is just one of the many aero engines used by the Japanese forces in WWII. Here's a list of the others. Shocked

http://en.wikipedia.org/wiki/List_of_Aircraft_engines_in_use_of_Japanese_Navy_Ai...
Apart from the German ones I have no idea if any were fuel-injected. Wink

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Reply #25 - Nov 6^th, 2006 at 6:49pm

Flying Trucker Ex Member

Thanks for another site Doug.

Cheers...Happy Landings...Doug

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Reply #26 - Nov 8^th, 2006 at 10:19pm

Flying Trucker Ex Member

Just a quick thought folks....I am trying to rationalize why carburetors were used on the Rolls Royce Merlin Aero Engine when the weather is such as it is in England.

I would think the air would be heavy with moisture and that being a contributing factor to Carburetor Ice.

If fuel injection was already in use in Europe then why would Rolls Royce not have looked at that option right at the beginning of the "Merlin" development?

I read that there was a weight to ratio factor concern but I would think that fuel injectiion would have been a benefit right from the start of development.

The cost, no I don't think so, if you develop something right from the start it proves to be cheaper in the long run.

Don't get me wrong I am not knocking the finest engine ever developed, would love to have one in the Land Rover but the old girl has a heavy foot.

It is wonderful when one has so much time on their hands they get to think about little details like this, and the information and knowledge one receives back helps to fill in the blanks and time.
Again thanks to everyone for their time and wonderful input. Wink

Cheers...Happy Landings...Doug

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Reply #27 - Nov 9^th, 2006 at 4:42am

Hagar Offline
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I was never an 'engine man' but this fascinates me. I've never seen carburettor icing mentioned in relation to aircraft powered by the Merlin. I read somewhere that the butterfly on Merlin carburettors was automatically heated by engine oil to prevent icing. I don't know which carbs this applied to & can't find any reference to it on the WWW. If it's true I have to wonder why this idea isn't common practice now.

Quote:

If fuel injection was already in use in Europe then why would Rolls Royce not have looked at that option right at the beginning of the "Merlin" development?

I'm sure they did. http://en.wikipedia.org/wiki/Rolls-Royce_Merlin
Quote:

The use of uninjected carburettors was calculated to give a higher specific power output, due to the lower temperature, and hence the greater density, of the fuel/air mixture, compared to injected systems.

German manufacturers were/are noted for their precision & also pioneered the use of diesel engines in aircraft. These would have been fuel-injected so the technology would have been available for petrol engines. http://www.casa.gov.au/fsa/2003/nov/58.pdf
(Not so long ago diesel fuel would have been liable to freeze in the tank in sub-zero conditions without winter additives. I've never heard of petrol freezing.)

PS. It's a long time since I worked on them but if I remember correctly the carburettor on the Gipsy Major engine is automatically heated from the engine exhaust. Our Tiger Moths had no carb heat control in the cockpit.

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Reply #28 - Nov 9^th, 2006 at 11:09am

Flying Trucker Ex Member

Hi Doug:

Here is a theory I have believed in for decades...time seems to prove me correct...but someday I hope to be proven wrong.

An inventor/designer/architect comes up with a new perfect gadget, let us just say a new aero engine for example.

It then goes through several more steps and finally on to a manufacturer.

When this new perfect gadget hits the market it is not so nearly perfect as money can be made by stock holders and individuals to add modifications to make this product better over the next couple of years.

All products are nowhere near perfect and I would say that modifications are justifiable during it's production run.

I think all too often a new perfect gadget does come along and mankinds greed raises it's ugly head. Sad

War to me does three things, lowers the population, lowers the unemployment rate and increases the wealth of certain individuals and corporations.

Now getting back to our beloved Rolls Royce Merlin Aero Engine, was it not the perfect engine when it won all those races attached to a certain float plane we all love.

I am not sure but it sure does make me wonder.

Cheers...Happy Landings...Doug

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Reply #29 - Nov 9^th, 2006 at 11:34am

Hagar Offline
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Quote:

Now getting back to our beloved Rolls Royce Merlin Aero Engine, was it not the perfect engine when it won all those races attached to a certain float plane we all love.

I am not sure but it sure does make me wonder.

That's a common fallacy Doug. The Merlin was basically a new design* intended as a stop-gap to fill the void between the Vulture and the Kestrel. The Griffon was not a development of the Merlin as many seem to think but the derated production version of the R-type engine used on the S6 seaplanes. http://www.solarnavigator.net/aviation_and_space_travel/rolls_royce_merlin_engin...

*PS. I think the Merlin was developed from a much earlier RR engine but can't find any details right now.

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