enginehistory.org

jjuutinen · Joined: 13 Jul 2003 Posts: 180

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

raustin · Guest

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

gryan · Guest

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

dbirch · Guest

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

gwhite · Joined: 13 Jul 2003 Posts: 58

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

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

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.

gwhite · Joined: 13 Jul 2003 Posts: 58

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.

jjuutinen · Joined: 13 Jul 2003 Posts: 180

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

jwells · Joined: 16 Sep 2003 Posts: 57 Location: Victoria, AUSTRALIA

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.

szielinski · Joined: 13 Jul 2003 Posts: 94 Location: Canberra, Australia

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.
_________________
“Make everything as simple as possible - but not simpler” – Einstein.

jjuutinen · Joined: 13 Jul 2003 Posts: 180

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.

szielinski · Joined: 13 Jul 2003 Posts: 94 Location: Canberra, Australia

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??
_________________
“Make everything as simple as possible - but not simpler” – Einstein.