Why didn't the Americans develop a match for the Merlin?

Somebody had forgotten to close a hatch properly, so it was full of water as well!

Here is the Danish Army Specific: The Centurion MK III was received as part of the MDAP program in 1953 (216), some of them after participating in the Korean War. To compensate for the notorious fuel-consumption a fuel trailer was delivered along with the MBT.

Weight: 50.800 kg (111.760 lb.).
Armor: 51 – 152 mm (2 – 6 inches).
….Engine: V12-cylinder Rolls-Royce Meteor Mk IV B, 27.027 cm3 (1648 cubic ….inches) displacement, liquid cooled.
….Horsepower: 650 at 2.550 rpm.
Transmission: 5-speed Merrit-Brown Z51R Mk. F gearbox.
Transfer case: 2-speed.
Electrical system: 24 volt, negative ground.
Brakes: N/A.
Fording depth:
without preparation: 1.40 m (54 inches).
with deep water fording kit: N/A.
Fuel type: Petrol.
Fuel capacity: 550 liters (121 gallons).
Range: 100 km (62 miles).
Crew: 4.
Armament: 84 mm gun with 64 rounds, Besa machine gun, 2 x 6 smoke dischargers.
Additional: Mounted with SCR-508 or SCR-528 radio.
The CFE-treaty, the result of the Negotiation on Conventional Armed Forces in Europe in 1990, stated that Denmark were allowed to posses 300 MBT´s. As a result 146 Centurions have been destroyed from 1993 – 95. 18 of the 146 MBT´s have gone to museums (2), static display (8) and range targets (8).

And one day there was a flying tank here! It should move a few hundred meters. The tracks etc. were rusted together, so it had to be lifted. But the crane had troubles. Even considering the extra concrete poured into the engine room as CFE compliance?

(55 tons?)

By redesigning the supercharger, Hooker increased the power of the early Merlins by a substantial figure virtually overnight.
One good thing came from the Vulture. It’s supercharger was used as the second stage for the 60 series Merlins.

The Rolls-Royce (Rover) Meteor was the tank engine. No supercharger and simpler carburettor. I’ve read 600hp, but I don’t know where. I’ve put Rover as the factory was part of the deal for Rolls-Royce to take over the jet engine.
Would this be the same engine used in MTB’s? Any naval types about?

Many years later, in collaboration with other retired designers, Hooker was responsible for turning the RB211 around and effectively saving Rolls-Royce.

The difference between the Merlin and the Allison can be summed up by saying that without the Merlin Britain would have been invaded, but the US without the Allison would have survived. The Allison got no development money until the US was at war. Rolls Royce had all the experience of the R in the S6 to call on to develop the Merlin during the 30’s in readiness for war.

The Merlin III’s and 45’s and their relatives that powered the Mk’s 1 to V spits had simple single stage, single speed superchargers and generally had a rated power @12lbs boost of 1300hp at 12,000 feet. The Allison V1710 was not too far from these ratings. Were the Merlin was different is that Rolls produced a range of Merlin’s within the 45,46,50 and 55 model range with different supercharger speeds and supercharger sizes that gave the engine a wide rage of available power options at different altitudes.

For example some of the low attitude engines produced 1500 plus hp @18lbs boost at 3000 feet. These powered the clipped, cropped and clapped series of Mk5’s. They were unmatched below 5.000 feet but totally out of it at 15000 or 20000 feet. Others were rated to produce 1000 plus hp at 20,000 feet but were sitting ducks at lower levels.

Enter the 2 stage supercharger designed by Stanley Hooker. This allowed the Merlin 61 to combine the best of both worlds. Take off power was only 1200 hp, but at 30,000 feet the pilot still had 1000hp available. It was this more consistent performance that was the critical factor.

A period of mechanical improvement resulted in engines that could produce more power for longer periods. Merlin 24’s for the Lancaster, 25’s for the Mossie and the 66 (266) for the spit IX (XVI)

The Merlin 66 that is often quoted as the MkIX engine did not enter service in significant numbers until 1944 and had a much lower rated attitude than most people realise. It could produce 1750hp at 5000 feet at plus18lbs in low blower or 1625hp in high blower at 12,500 feet. These figures are for 100/130 fuel

If 100/150 fuel was used 25lb boost could be used and 200hp added to the ratings, but the low blower attitude went down to 3000 feet and the high blower rating to down to 11,000 feet.

The above figures suited the environment that the spitfire found itself fighting in during the latter part of the war.

As for the Americans, the US air force wanted to use turbo supercharges, and as the Allison was primarily an Airforce engine no money was expended on a decent mechanical supercharger. But the Technology did exist and one has only to look to the US Navy and the Wildcat, Hellcat, and especially the Corsair to see some magnificent 2 stage supercharges. The Post war F4U5 Corsair had the most magnificent 2 stage variable speed supercharger for its R2800, its size almost that of the engine.

The Allison’s in the Lightning could produce 1500 hp at 30,000 ft with their Turbo’s, but again not enough money was spent sorting out the controls to stop the engine detonating and destroying itself in the European environment. The intercooler / after coolers were completely inadequate. It was easier to ditch the Lightning and substitute the Mustang.

Originally posted by VoyTech
Mark, your statement is only true with regard to the air combat over Western Europe, i. e. strategic bombings of Britain by the Luftwaffe, and then strategic bombings of occupied Europe/Germany by the RAF/USAAF.

Yes VT – that was what I had in mind, I was thinking about the Merlin in its original geographical context!

The centurion main battle tank engine was called Rolls Royce Meteor (650 BHP @ 2550 rpm). Wasn’t this a version of the Merlin. Without supercharge apparantly. Any tankers here? Also seem to remember a trailer with fuel for the Centurion to “extend” range.

Best regards

I think there is a view that the late Allison models, such as in the P-63 had got their supercharger limitations well and truly sorted out – indeed they had infinitely variable automatic adjustment rather than 2-speed selections as on the Merlin. However, by this time, there were very few aircraft to take advantage as the US was using either radials or Packard Merlins and the P-63 had a stigma from looking like the P-39.

The survival of the Allison in non-aviation activities such as boat racing and tractor pulling, not to mention incorporation of various parts and ideas in the current 3000+HP racing Merlins must say something about its fundamental merits.

Originally posted by Mark V
The general trend in WWII was for air combat to take place at increasingly higher altitudes and the Merlin met this challenge.

Mark, your statement is only true with regard to the air combat over Western Europe, i. e. strategic bombings of Britain by the Luftwaffe, and then strategic bombings of occupied Europe/Germany by the RAF/USAAF. If you look at any theatre where ground forces were involved, low altitude combat was the norm. The Russians, for example, preferred the Allison-powered Airacobra to the Merlin-powered Spitfire in their combat units.
The only decent high altitude fighters (I mean those used operationally) were developed:
1) by the Brits for defence (Spitfire variants)
2) by the Germans for defence (109 and 190 variants)
3) by the Americans for bomber escort duties (Merlin-powered P-51s and P-47s with supercharged radials).

Coming back to the original question, wasn’t it that the Americans didn’t need (in their own opinion) a good high altitude engine for their fighters? They obviously didn’t think (quite right) about air defence of their own territory from strategic bombings. And by the time they saw the need for a high altitude fighter to escort their bombers, they had the Merlin and the supercharged radials (developed for their heavies originally) to choose from.

Over 2000hp for the Merlin in the Hornet, exact figure depending on which book you read.
It was fortunate, as Mark12 said, that (Sir) Stanley Hooker was in the right place at the right time. He was probably the world expert on supercharging, it’s just that nobody, including himself, knew it to start with! He was a pure mathematician, with a particular interest in fluid dynamics. I’m confused just writing it down but apparently it’s perfect for improving superchargers.
Autobiography, “Not Much of an Engineer” is an excellent read.

The altitude/supercharger issue is the key. The general trend in WWII was for air combat to take place at increasingly higher altitudes and the Merlin met this challenge. There were of course exceptions, for example the Spitfire XII with a single stage superchaged Griffon (not a Merlin but it illustrates the point), more than adequate in meeeting the low level raiders that were a significant problem at that stage of the war

Supercharging

Without doubt the Merlin’s success was down to a basically sound core capable of handling an increasing range of multiple speed and stage Superchargers delivering ever more power at higher altitudes.

The key is the fantastic supercharger development and we have to thank Sir Stanley Hooker and the team for that.

So under 1000 h.p. on the Mk I Spitfire rising to 1720 h.p. on the Mk XVI. Still 27 litres – no change to the frontal area – a few inches longer – brilliant.

Mark

Not being an engineer, I’m reluctant to make a comment, however, I understood it wasn’t as simple as Merlin = excellent, Alinson = no good, but about the altitude that the engines operated at. Alinson Mustangs / A-36s were popular with their pilots at LOW level, weren’t they? Many engines were designed for low altitude performance, and few cut it at high altitudes. Anyone able to explain this better?

Cheers

Well, this thread managed to create some discussion, which pleases me no end. It was never intended to spark the US -v- the rest debate as I have no time for that crap.

Given that Allisons failed to reached the heights of performance achieved by the Merlin, were there any other attempts to develop American in-line engines during the war?

With the Packard-Merlins, were they developed separately from R-R built engines to create separate model identities, and were they more or less powerful than the R-R engines?

Finally, were P-51’s fitted with British built Merlins apart from the prototype ugly looking thing recently shown on another post?

Regards

Wombat

oops, forgive my ignorance, I thought it was only Packard….

Still, good to learn one thing new everyday…

Only 30,000 or so. 🙂

So, did Ford end up licence-building Merlins ?

Andy,

I would be happy to post some pictures of my airplanes, but I haven’t got a clue how to do it.

You can see my Sea Fury at www.warbirdsresourcegroup.org

Look under the Sea Fury registry for “Southern Cross” and you can see some current pictures.

I also fly an AT-6F Texan (Harvard) for my trainer piston, an L-39C for trainer jet (and formation work…I have 5 friends with L-39s and we get together and fly whenever we can), and a MiG-17F for fighter jet. The MiG, at 300+ gallons per hour is a thirsty beast, but with a climb of 16,000’+ fpm nothing else comes close. God love the good ole USA for allowing us to fly these airplanes after 9/11.

I think there is a web site somewhere with the following motto, “Communism, bad politics, good airplanes”. My thoughts exactly.

Any information on Sea Furies would be most welcome. Mine was one of the Iraq AF planes brought over in the 1980s. Anyone know anything more about these airplanes?

I wouldn’t know about the relative merits of RR and Packard. A recently deceased ex-RAF engine fitter complained bitterly about the Packard, but, (a) he was a grumpy old s*d, and (b) I’ve never heard of anybody else complaining. As an aside, I understand the toolkit supplied with the Packard engines was superb.

However, there were problems when Ford were asked to make the Merlin at Trafford Park. They said they couldn’t make them, Rolls-Royce said “Not surprised. Tolerances too tight for you?” Ford said “No, the opposite. Far too lax, everything would have to be individually matched”. I can’t look up the exact details at the moment, the book(s) I think it’s in are still with the estate of the aforementioned grumpy old s*d.

Further to the above, the Merlin was re-drawn to motor industry tolerances. I would assume, with the Ford production coming first, it’s likely that the revised drawings were sent to Packard.
If so it’s probable that the Packard was built to tighter tolerances.

Sea Fury

Hello Mr SR Patterson.
Why not post some pictures of your aircraft?
I for one would be glad to see them.
And I’ve been posting here for a little while and it’s usually quite polite.
Here’s another question about Merlins though.
Who built them to the tightest engineering tolerances–Packard or RR??
I’ve heard both sides of that argument put forward over the years.
Any thoughts anyone?
All the best
Andy.

I thought my Boutros didn’t show? More cream nurse!:D