Rolls Royce Merlin coolant flow

[Centaurus]

Friend of mine in New Zealand is a keen aviation historian and would like to have an answer if possible to the following question of rate of coolant flow regarding Rolls Royce Merlin engines.
............................................................ ......................

Tally Ho gentlemen. You know lotsa stuff about Merlins so can you assist me?

I have one figure of 30 gp/minute and another of 240 gpm....so I am befuddled. The engine oil flow rate is about 20 gpm and I am guessing that coolant could be about 100 gpm at 2700 rpm.

Also, I hope that all is jolly with you.
Cheers,
Ye Feen....the fruitless searcher.
............................................................ .......................................

[Peter-RB]

Rolls Royce would say "Sufficient" but I have a pal with one working so will ask !
PeterR-B

[India Four Two]

Centaurus,

I received this via an aviation news letter. I don't know its provenance or whether it is correct, but it's a great read:
The Rolls Royce Merlin:
In one second, the V-12 Rolls-Royce Merlin engine would have gone through 60 revolutions, with each of the 48 valves slamming open and closed 30 times. The twenty four spark plugs have fired 720 times. Each piston has travelled a total of 60 feet in linear distance at an average speed of 41 miles per hour, with the direction of movement reversing 180° after every 6 inches.

Three hundred and sixty power pulses have been transmitted to the crankshaft, making 360 sonic booms as the exhaust gas is expelled from the cylinder with a velocity exceeding the speed of sound.

The water pump impeller has spun 90 revolutions, sending 4 gallons of coolant surging through the engine and radiators. The oil pumps have forced 47 fluid ounces, roughly one-third gallon, of oil through the engine, oil cooler, and oil tank, scavenging heat and lubricating the flailing machinery.

The supercharger rotor has completed 348 revolutions, its rim spinning at Mach 1, forcing 4.2 pounds or 55 ft³ of ambient air into the combustion chambers under 3 atmospheres of boost pressure.

Around 9 fluid ounces of high octane aviation fuel, 7,843 BTUs of energy, has been injected into the carburettor along with 5.3 fluid ounces of methanol/water anti-detonant injection fluid. Perhaps 1/8 fluid ounce of engine oil has been either combusted or blown overboard via the crankcase breather tube. Over 1.65 million foot pounds of work have been done, the equivalent of lifting a station wagon to the top of the Statue of Liberty.

In that one second, the hard-running Merlin has turned the propeller through 25 complete revolutions, with each of the blade tips having arced through a distance of 884 feet at a rotational velocity of 0.8 Mach. Fifteen fluid ounces of spray bar water has been atomized and spread across the face of the radiator to accelerate the transfer of waste heat from the cooling system to the atmosphere.

In that one second, the aircraft itself has travelled 704 feet, close to 1/8 mile, or roughly 1.5% of a single lap. The pilot's heart has taken 1.5 beats, pumping 5.4 fluid ounces of blood through his body at a peak pressure of 4.7 inches of mercury over ambient pressure. Our pilot happened to inspire during our measured second, inhaling approximately 30 cubic inches (0.5 liter) of oxygen from the on-board system, and 2.4 million, yes million, new red blood cells have been formed in the pilot's bone marrow.Four gallons per second of coolant matches your quoted 240 gpm number and 1/3 gallon per second of oil matches your 20 gpm number. I'm assuming these are US gallons, based on the references to the Statue of Liberty, spray bars and laps.

704 feet per second is 417 kts, so this is clearly a flat-out racing engine.

I42

[marianoberna]

Yes it is indeed a racing plane, here's the complete version

One Second in the Life of a Racer
by Tom Fey

The Unlimiteds go flashing through the racecourse, engines howling, air shearing, heat waves streaming. Four hundred eighty miles an hour is 8 miles a minute, and the elite racers take about 70 seconds to cover the 9.1 mile Reno course. If you could take a souped P-51 racer flying the circuit at Reno, slow time down, and examine just one second, what would you find?
In that one second, the V-12 Rolls-Royce Merlin engine would have gone through 60 revolutions, with each of the 48 valves slamming open and closed 30 times. The twenty four spark plugs have fired 720 times. Each piston has traveled a total of 60 feet in linear distance at an average speed of 41 miles per hour, with the direction of movement reversing 180° after every 6 inches. Three hundred and sixty power pulses have been transmitted to the crankshaft, making 360 sonic booms as the exhaust gas is expelled from the cylinder with a velocity exceeding the speed of sound. The water pump impeller has spun 90 revolutions, sending 4 gallons of coolant surging through the engine and radiators. The oil pumps have forced 47 fluid ounces, roughly one-third gallon, of oil through the engine, oil cooler, and oil tank, scavenging heat and lubricating the flailing machinery. The supercharger rotor has completed 348 revolutions, its rim spinning at Mach 1, forcing 4.2 pounds or 55 ft³ of ambient air into the combustion chambers under 3 atmospheres of boost pressure. Around 9 fluid ounces of high octane aviation fuel, 7,843 BTUs of energy, has been injected into the carburetor along with 5.3 fluid ounces of methanol/water anti-detonant injection fluid. Perhaps 1/8 fluid ounce of engine oil has been either combusted or blown overboard via the crankcase breather tube. Over 1.65 million foot pounds of work have been done, the equivalent of lifting a station wagon to the top of the Statue of Liberty.
In that one second, the hard-running Merlin has turned the propeller through 25 complete revolutions, with each of the blade tips having arced through a distance of 884 feet at a rotational velocity of 0.8 Mach. Fifteen fluid ounces of spray bar water has been atomized and spread across the face of the radiator to accelerate the transfer of waste heat from the cooling system to the atmosphere.
In that one second, the aircraft itself has traveled 704 feet, close to 1/8 mile, or roughly 1.5% of a single lap. The pilot's heart has taken 1.5 beats, pumping 5.4 fluid ounces of blood through his body at a peak pressure of 4.7 inches of mercury over ambient pressure. Our pilot happened to inspire during our measured second, inhaling approximately 30 cubic inches (0.5 liter) of oxygen from the on-board system, and 2.4 million, yes million, new red blood cells have been formed in the pilot's bone marrow.
In just one second, an amazing sequence of events have taken place beneath those polished cowlings and visored helmets. It's the world's fastest motorsport. Don't blink!

[Effluent Man]

That fuel consumption equates to around a gallon every 18 seconds at full power.Presumably the consumption at the most economical cruising speed of (say) 220 knots would be around 25% i.e. covering around twice the distance per unit used?

[India Four Two]

EM,

That's consistent with the 60 gal/hr number that I vaguely remember.

Out of interest, I looked up this:

Spitfire Mk I Performance Testing (http://www.spitfireperformance.com/spitfire-I.html)

Well worth reading. It includes a comparison with a Hurricane and an Me109E-3.

Although it's an early Merlin, consumption at 7000' was 24 gal/hr at 185 mph and 62 gal/hr at 280 mph (IAS)