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RR Crecy

 
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jjuutinen



Joined: 13 Jul 2003
Posts: 180

PostPosted: Thu Dec 22, 2005 04:36    Post subject: RR Crecy Reply with quote

I was rereading the RRHT book on the Crecy and it refreshed my memory of how great potentiatl it did have. So, how about an engine:
-that had potential 5000 hp from less than 2000 lb weight
-cruising SFC of .35 lb/hp/h
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raustin
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PostPosted: Tue Dec 27, 2005 15:26    Post subject: Reply with quote

Hi Jukka, I have this book too, and I'm convinced that it would have been a great engine. I particularly like the developments that Tresilian had come up with, from his calculations to get the engine down to 7 1/2 litres, 16 cylinder 'X' configuration and still put out 2500 hp. David Birch's musings on a 24 cylinder 'X' engine with a Griffon bore and 3 1/2" stroke would certainly put it into the other thread posted here, on the ultimate piston engine. with a calculated output of 8100 hp.
Cheers, Robert
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gryan
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PostPosted: Tue Dec 27, 2005 18:58    Post subject: Crecy sounds Reply with quote

The RR Crecy would have sounded pretty good as well. I've read that it made a fantastic noise. Is there a tape?
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dbirch



Joined: 30 Apr 2007
Posts: 14

PostPosted: Thu Dec 13, 2007 03:42    Post subject: Reply with quote

Sorry, no recordings of the Crecy (you would have to have stood well back with the microphone!) Believe or not, testers used to stand at the side of the engine making adjustments, etc, with the most basic of earplugs in their lug 'oles.

Glad to see that we have some Crecy-lovers out there. Doesn't the 90-degree cylinder block configuration look just right!

Dave Birch, RRHT
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gwhite



Joined: 13 Jul 2003
Posts: 58

PostPosted: Thu Dec 13, 2007 08:47    Post subject: Reply with quote

I'm sure Dave won't mind a slight clarifiaction; lug 'ole for the non Anglophile is the ear..!!
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jsewell



Joined: 28 Mar 2006
Posts: 4
Location: Little Rock, AR

PostPosted: Mon Dec 17, 2007 09:37    Post subject: Reply with quote

bought the book a while back myself, mostly to learn about the 2 cycle, sleeve valve operation.
a marvelous engine design the Crecy. i do find the counter arguments about its potential interesting as well.
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gwhite



Joined: 13 Jul 2003
Posts: 58

PostPosted: Thu Dec 20, 2007 06:33    Post subject: Reply with quote

Although the Crecy had great potential, insurmountable problems stymied its development. After R-R wisely threw in the towel to concentrate on gas turbines, Ricardo soldiered on but to no avail. According to Ricardo, the greatest problem was piston cooling. He tried many ideas including his “cocktail shaker” which is used to this day for piston cooling. However, none of the remedies were satisfactory for the Crecy.
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jjuutinen



Joined: 13 Jul 2003
Posts: 180

PostPosted: Thu Dec 20, 2007 08:03    Post subject: Reply with quote

Were e.g. copper alloy pistons tried to improve piston cooling? How high oil flows were injected to the undersides of the pistons?
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jwells



Joined: 16 Sep 2003
Posts: 55
Location: Victoria, AUSTRALIA

PostPosted: Sat Dec 22, 2007 22:24    Post subject: CRECY INVERTED. Reply with quote

I've always wondered why some consideration wasn't given to developing the Crecy as an inverted V-12. Such configuration might have solved some problems including:
1/ forward visibility problems in single-engined installations. As a 90 deg. Vee, the Crecy was about 28% wider than a Merlin which, from all accounts was not easy to see over so, inverting the engine might have helped in this respect.
2/ piston cooling was a major difficulty with the Crecy, as is mentioned several times in the book. Operating as an inverted Vee, the piston interiors would have been constantly bathed in engine oil which could have resulted in no need for the pumping of oil along the con-rods, as was tried.
3/ sleeve lubrication would have been enhanced if the cylinder blocks were pointing down instead of up.
4/ combustion chamber 'bulbs' were there to contain the sprayed fuel from the injectors momentarily thus creating the 'stratified charge' effect which was crucial to the operation of the Crecy. If the engine was inverted, the fuel would have been kept in them slightly longer by gravity which would have little effect in normal operation but might have made starting and idling a little easier.
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szielinski



Joined: 13 Jul 2003
Posts: 96
Location: Canberra, Australia

PostPosted: Wed Jan 02, 2008 22:07    Post subject: Reply with quote

Jerry,
I think the visibility aspect would not be much of a problem as the height of the cylinder banks would not be as great as an OHC 4-stroke such as a Merlin or Griffon.
Having said that, the main engines never got past sleeves and pistons overheating, which overshadows the fact that something would have to be done with all the injector/plumbing leaks eventually. I think it is (was?) possible that they may have needed to go to a cam-driven injector pump above each cylinder; thus removing the goldilocks piping but adding to engine height and negating my above point.
All,
The other disappointment was that there wasn't much 'done' with the air that went through the engine. In the book you may remember the guy who was involved in supercharger development, he opined that in his opinion the main problem with the Crecy was the lb air/hp consumption, ~4x that of the Merlin from memory.
Overall I think it was an awesome engine. If only they had listened to Hives and "gave 'er more oil", we might be driving reliable, economical diesel "Crecys" today.
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jjuutinen



Joined: 13 Jul 2003
Posts: 180

PostPosted: Thu Jan 03, 2008 08:55    Post subject: Reply with quote

I have a feeling that those injection piping leaks were solvable. They definitely were in those 100,000+ German engines from DB, Jumo and BMW. Perhaps Bill Gunston did have it right when he decsribed that British industry could not have mass produced those injection pumps.
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szielinski



Joined: 13 Jul 2003
Posts: 96
Location: Canberra, Australia

PostPosted: Thu Jan 03, 2008 15:02    Post subject: Reply with quote

You might be right, the German injector set-up had as long a route from the pump, and they didn't use the stress relieving bends.

ja, das english fadenscheinig installationen und zapfendusen??
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