ROLLS-ROYCE CRECY

[THE DOCTOR]

according to the RRHT book No. 21, the 2 stroke, V-12,

direct injection, sleeve valve CRECY. had an amazing exhaust

note!!!

That right; 2-stroke!!!!


Da Doc

[52eme]

the RR Crecy was indeed a beautiful piece of engineering.
V-12, 26.1Litre and.. 5000hp

it aparently had avery distinctive noise because the valves were set as to let the exhaust gaz exit the cylinder very rapidly and give additional thrust.

Click Here For Image

RR produced some pretty amazing engines in the 30s and 40s, the Exe and Pennine X-6 and Eagle H-24...

now Doc, what kind of power do you think you could get out of that Crecy ?


Regards
fred

(admin note *edited message to link to image rather than display image, which is a copyright violation*)

[THE DOCTOR]

IS THIS THE FRED THAT OWNS THE ROLLS-ROYCE KESTREL

THAT WAS TAKEN TO PECIES AT THE HOLLISTER AIRPORT ????

REGUARDING HOTTING UP THE CRECY, SIR STANLEY HOOKER

RELATES IN HIS BOOK "NOT MUCH OF AN ENGINEER"

THE TWO STROKE CYCLE WAS CAUSING SEVERE PISTON

OVERHEATING PROBLEMS DURING THE TEST PROGRAM.

OF COURSE TODAY WE COULD MAKE A CERAMIC/XXXX

PISTON!!!!!

IF WE ONLY HAD DA MONEY; WE COULD GO REALLY FAST.........


DA DOC

[52eme]

nope, not the good fred, sorry..
actually i'm the fred from paris, and Don B must have talked to you about me.. i hope you'll be able to join us for the SARH symposium next month..

fred

[Peashooter]

Here's more on the Crecy and other famous RR Aero engines. Peas

http://www.stobbe.dk/industrial-products/technical-literature/combustion-engines/rolls-royce/Rolls-aircraft.html

[Unregistered]

Re: ROLLS-ROYCE CRECY

<< THE TWO STROKE CYCLE WAS CAUSING SEVERE PISTON

OVERHEATING PROBLEMS DURING THE TEST PROGRAM.>>

This engine set the absolute thermodynamic record for several decades for piston engines at over 20 HP/sq. in. of piston area. RPM, BMEP, and all other factors not withstanding, This figure represents a SEVERE thermodynamic load (heat flux) to and through the piston. This is independant of the cycle (two vs. four stroke) and more dependant on the obscene amount of power and heat.

Difficulties existed in sufficient cooling oil spray to the piston back side and top ring welding due to very high maximum combustion pressures. The sleave valve also inhibits piston heat transfer to the cylinder. However, it is a fascinating architecture and may have possibilities with the application of modern materials and methods. As a two stroke, it would have only 60 to 70% of the mechanical stress of a four stroke with the same power. This would lead to a 5000 HP engine suffering the same physical stresses as the latest Thorn Merlins at ~3400 HP.

Cooling those pistons would be a real -itch though...

Eric Ahlstrom

[First time Juke]

Re: ROLLS-ROYCE CRECY

Model engines are 90 % twostrokes. Some of them can do 28 000 rpm. Italian Rossi for example can put out ca. 2.5 hp with 3.6 ccm ( .20 cuin ) displacement. Fuel contains the lubricant ( 20 % ) and fuel is methanol + 10 to 20 % nitromethanol.
I did put an 1.4 hp producing engine on 900 gram ( flyweight ) model and it flew so fast that I was experiencing very unfamiliar feelings ( like will I survive this ordeal ). That was over 1 hp / kilo power to weight ratio...I have become a lot better flyer since that, but never dared to put that powerful engine again on my small models ( no flaps etc. ).

Well this is far away from the topic.

[AirDOGGe]

Re: ROLLS-ROYCE CRECY

it would have only 60 to 70% of the mechanical stress of a four stroke with the same power.

The Napier Nomad was another impressive 2-stroker:

A 12-cylinder two-stroke turbo-compounded Diesel, the Nomad was one of the most complex and fuel-effecient engines ever built.

There's several large photos of the Napier on the NASM engines webpages...Check out the 36 cylinder Lycoming XR-7755 while you are there....what a beast!

http://www.enginehistory.org/nasm2.htm

.

[matt]

Re: ROLLS-ROYCE CRECY

i've heard that once a two stroke reaches a certain size in cu. in.'s it's ability to prduce more power than a four stroke dies, is this true?

if so, how did the crecy produce 5000 hp?

[AAFO_WSagar]

Re: ROLLS-ROYCE CRECY

i've heard that once a two stroke reaches a certain size in cu. in.'s it's ability to prduce more power than a four stroke dies, is this true?

if so, how did the crecy produce 5000 hp?

Matt, I might be blowin smoke out of an orfice, but, likely, that forumla, if it's right, would apply on a per cylinder basis. If I'm not mistaken, the Crecy had a TON of cylinders. Maybe each of them did not exceed the size?

Wayne

[AirDOGGe]

Re: ROLLS-ROYCE CRECY

5000hp / 12 cylinders = 416.666 hp per cyl.... Wow!

Considering that for an equal rpm the 2-stroker has twice as many power strokes most likely has something to do with it. Horsepower = torque x rpm. I'd like to find out what the max RPM of the Crecy was...

I haven't heard of the 2-cycle vs 4-cycle displacement problem, but it does state the 5000 hp horsepower rating at the RR engine website Peashooter posted:

Crecy – V12, 90°, sleeve-valve, liquid cooled, 26.1 litre, supercharged, two-stroke, mechanical fuel injection (from Focke Wolf 190) Otto-engine. The 1942 prototype had surprisingly low fuel consumption at the highest power output. In December of 1945, after eight years of development, work on the Crecy was terminated. At that time the Crecy was capable of double the horsepower of conventional 4-stroke designs of the same displacement. Only six Crecy engines were built, all with even serial numbers (2, 4, 6, 8, 10 and 12). This has led to confusion as to the numbers made. Crecy engine #10, achieved the highest test horsepower in December 1944, putting out the equivalent of 5,000 brake horsepower.

[Type327unreg]

Re: ROLLS-ROYCE CRECY

i've heard that once a two stroke reaches a certain size in cu. in.'s it's ability to prduce more power than a four stroke dies, is this true?

if so, how did the crecy produce 5000 hp?

Clearly you've been speaking to four-stroke bigots Most, if not all, of the really big engines out there are two-stroke. I'm talking here of engines with displacements up into the thousands and even tens of thousands of cubic inches per cylinder. No, those aren't typos, tens of thousands, per cylinder. These units don't actually produce a lot of power for their size (it's hard to make a lot of power when your redline is at maybe 200 rpm), but that's not what they're built for, they're built for torque. Torque up in the millions of lb/ft for the really big ones. Two-strokes of this size are pretty much uniformly diesel units, and I believe in the early design stages the Crecy was going to be a diesel, I may be thinking of another experimental Rolls Royce from the period though. With two-strokes dominating in the arena of small engines too, it's really just the bit in the middle where four-strokes are, for now, allowed to pretend they're king

Type327, posting unregistered because I changed my email address and forgot my password, I'm so organised

[AAFO_WSagar]

Re: ROLLS-ROYCE CRECY

Type327, posting unregistered because I changed my email address and forgot my password, I'm so organised

Three Two Seven... click on the contact us link on the bottom, send me an email with your username or reasonable facsimile, and or, your old email address, as well as, your new email addy and I'll get the board software to send you a reset notice. May have to wait till late tomorrow or the next day, as I'm gonna be in the air for a few hours comin up here tomorrow..

Wayne

[AirDOGGe]

Re: ROLLS-ROYCE CRECY

I'm talking here of engines with displacements up into the thousands and even tens of thousands of cubic inches per cylinder. No, those aren't typos, tens of thousands, per cylinder.

You mean like this house-size monster? (2-story house, that is...)

http://www.bath.ac.uk/~ccsshb/12cyl/ <--click here to see it!

-----------------------------------------------------------------

The Most Powerful Diesel Engine in the World!

"The Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine is the most powerful and most efficient prime-mover in the world today. "

"The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower."

"14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm
"

[Type327unreg]

Re: ROLLS-ROYCE CRECY

Three Two Seven... click on the contact us link on the bottom, send me an email with your username or reasonable facsimile, and or, your old email address, as well as, your new email addy and I'll get the board software to send you a reset notice. May have to wait till late tomorrow or the next day, as I'm gonna be in the air for a few hours comin up here tomorrow..

Wayne

Cheers Wayne email sent.

Eddie