could the Allison engine have done what the Rolls Royce Merlin did?

[buffnut453]

I remain perplexed at the persistence of the myth that the Supermarine S6B led directly to the Spitfire. After all, does anyone claim that the Macchi C200, C202 or C205 are direct descendants of the M52, M67 or M72 Schneider Trophy racers? How about the Curtiss P-36 evolving from the R3C-2, R3C-4 or the F6C-1? If there isn't any parental linkage within those manufacturers' lines, then why do we apply one to Supermarine?

Immediately following the 1931 Schneider Trophy race, the Air Ministry issued Specification F.7/30 as a proposed replacement for the Gloster Gauntlet. Supermarine responded with the Type 224 which is pictured below. A Spitfire it ain't:

The Supermarine Type 224 was powered by a Rolls Royce Goshawk engine and employed evaporative cooling. Note that the Goshawk was developed from the Kestrel and NOT from the R engines. It was ultimately unsuccessful (its top speed was just 228 mph) in competing for the F.7/30 specification. The winning aircraft was the Gloster Gladiator.

Mitchell had further discussions with the Air Ministry to try and sell the Type 224. He proposed a different wing, tail and engine configurations that theoretically would increase the top speed to 265 mph. However, the Air Ministry felt that an entirely new design was required rather than evolutions of the 224. This thinking was driven, in part, by growing recognition that "modern" fighters would need at least 8 rifle calibre machine guns and the Type 224 could only carry four.

Following the failure of the Type 224, Mitchell went back to the drawing board to create the Type 300 which was much more like what we know as a Spitfire. However, it was a completely different design from the Type 224, with retractable undercarriage, enclosed cockpit, and (eventually) the thin, elliptical wing that became the hallmark of the Spitfire design.

 

[GregP]

Uuhhh, Bufnut,

I wasn't the one claiming the linkage between the Schneider Cup and the Spitfire. It's all the pesky references saying that. Just FYI.

Maybe Vought-Sikorsky stole the Corsair's inverted gull wings from Supermarine? And moved the bullseye back a bit for pilot comfort.

 

[buffnut453]

Uuhhh, Bufnut,

I wasn't the one claiming the linkage between the Schneider Cup and the Spitfire. It's all the pesky references saying that. Just FYI.

Maybe Vought-Sikorsky stole the Corsair's inverted gull wings from Supermarine? And moved the bullseye back a bit for pilot comfort.

I know. My last post wasn't an oblique reference to you. It was a general rant about the common associations of the Supermarine S6 and Spitfire. IMHO, the Spitfire was descended from the S6 in the same way that the Hurricane was descended from the Sopwith Snipe.

Re the Corsair...you may be right. The wing/undercarriage set-up on the Type 224 also reminds me of the Stuka.

 

[Shortround6]

Lets see.

They both use a propeller in the Front.................................................................
They both use a propeller attached to the engine (no shaft).....................
They both put the pilot behind the engine........................................................
They both use a single vertical fin and rudder.................................................
They both use single horizontal stabilizer at the rear of the plane.........

They both use the same airfoil...............................................................................
They both use the same wing planform (shape).............................................
They both use the same wing contruction........................................................
They both use landing flaps....................................................................................
They both store fuel in the fuselage....................................................................


At quick look the S6B and the Supermarine 300 seem to have in common that they both are tractor low wing monoplanes with a conventional engine installation and a conventional tail.
At least this had a cantilever wing and had the fuel tank in the fuselage.

 

[Frog]

American tanks were rationed in their use of HVAP ammunition (tungsten cored) for the same reason.

Another reason was that, according US doctrine, the tank destroyers, tasked with anti-tank mission, had higher priority for HVAP resupply, while the tank job was infantry support.

 

[rinkol]

Why would one end up with a monster-sized fighter powered by a turbo V-1710?
The gas hog was patiently faster, more rugged and heavier armed than any fighter of ww2.

You need ducting for air and exhaust gases and an intercooler in addition to the compressor/turbine combo. You either end up with a cockpit near the tail (XP-37) or run the ducting past the cockpit (Fw 190C and XP-60A). The latter spoils the advantage of the in-line engine in minimizing frontal area.

 

[GregP]

"Development" doesn't mean "looks like."

It means similar design and/or construction. As for the Schneider Cup engines becoming the Merlin, Rolls-Royce might not have known what WORKED, but they likely had a definite handle on what DIDN'T WORK. Many things built from Legos don't look all that similar, but all are just a collection of boxes stuck together.

Many design features of the Merlin came from the Buzzard and the Type R engines. The sum of what Rolls Royce had learned making production and racing engines resulted in the Merlin and Griffon (basically a bored out Merlin type engine), particularly the Buzzard and the Type R ... according to many sources that are not me. I'm old, but I wasn't around when the Merlin was being designed.

Moreover, I have no stake in whether or not the claim is true. However it came to be, the Merlin was and is a good one!

 

[markstuk]

Why would one end up with a monster-sized fighter powered by a turbo V-1710?
The gas hog was patiently faster, more rugged and heavier armed than any fighter of ww2.

Heaviest armament? 4 x 20mm hs cannons as in the tempest are significantly more destructive than 8 X .50's..

 

[Frog]

I know. My last post wasn't an oblique reference to you. It was a general rant about the common associations of the Supermarine S6 and Spitfire. IMHO, the Spitfire was descended from the S6 in the same way that the Hurricane was descended from the Sopwith Snipe.

Re the Corsair...you may be right. The wing/undercarriage set-up on the Type 224 also reminds me of the Stuka.

And the Stuka was developped around a RR Kestrel...

 

[Thumpalumpacus]

And the Stuka was developped around a RR Kestrel...

So was the Me-109, no?

 

[Frog]

So was the Me-109, no?

And also fitted with a RR Merlin...

 

[Shortround6]

the Merlin and Griffon (basically a bored out Merlin type engine), particularly the Buzzard and the Type R .

The Buzzard and the R and the Griffon all used the same bore and stroke. The Buzzard and R predated the Merlin (Merlin is a reduced bore and stoke R?) and the Griffin I was running in 1933. The RR PV 12 first ran in Oct 1933 which really makes it hard for the Buzzard and R to be a bored out Merlin, even basically, unless Dr. Who was on the design team.

Airplane engine makers were an lot less prone to boring out engine than they were to modifying engines of the same bore and stoke to operate at higher rpm or higher pressures or both.

You may have to go deeper into the details, like different numbers or types of piston rings. Any notes on valves or valve timing. We know that the R changed to articulating connecting rods. The Merlin went back fork and blade rods.
RR learned a lot, but that doesn't mean the Merlin was scaled down or modified in any large way from the early engines.
Rowledge had worked at Napier and had a pretty good idea of what it took Napier to get the Lion engine up to 900hp or more in the earlier Schneider trophy racers.
It doesn't seem like

 

[Reluctant Poster]

Its all explained here!

Rolls-Royce Merlin and Kestrel - Wonders of World Aviation

Representative of the name of Rolls Royce today are the Kestrel and Merlin types of engines, both of which are extensively used in high-performance service aircraft, and are described in this chapter.

www.wondersofworldaviation.com

 

[Reluctant Poster]

They probably did. Again, unfortunately, the effects of whatever the improvements they whipped up for the V-1710 seem to be very, very elusive until too late. If someone can correct me on this I'd be very grateful.



Agreed on the 2nd sentence there, too bad PPD disagrees (disagreed).



Army didn't 'discovered' that adding a turbo would greatly improve things while testing the early B-17 prototypes, they knew it will, since they were championing the research wrt. turbocharging through 1930s, and were using aircraft with turboed engine(s) in 1930s.
Engine on the B-17 is one thing, addition of turbo is another thing.



One is left to question of just how the under-staffed PPD was able to solve the addition of turbochargers for B-17s already in 1939. Also - was the solution of supercharger problems just due to the work of PPD, or someone else sould be mentioned, perhaps the company making B-17s, and/or company making turboes?



They certainly did.
I've read a lot of NACA reports, just like a lot of other enthusiasts. Problem is when someone muddles the water for no particular reason, bar to paint the (any) institution in the best light possible. Nobody was twisting the arms of the writer to claim the things he claimed in the article quoted before.
A writer has test report(s) that prove that V-1710 was with 'basic flaws' making any improvement a waste of resources? Point out to the test reports, or don't mention that at all if there is no proof.



Thank you.
I guess both you any I know that a major performance jump for the Spitfires and Mustangs came from installation of ever-better engines after all.

I gathered together the NACA vs Allison reports I have and attached them as you note NACA were a little late for implementation

 

[Reluctant Poster]

I gathered together the NACA vs Allison reports I have and attached them as you note NACA were a little late for implementation

Hers a couple more.

 

[Reluctant Poster]

Per Dan Whitney in "Vee's for Victory"
XP-82 was to be powered with the Packard Merlin V-1650-23/25
XP-82A would have the Allison F32R/L V-1710-119/121 (Aircraft cancelled)
P-82B Allison offered the F33 R/L engine but the planes were produced with Merlin engines.
P-82C and P-82D were P-82B aircraft modified to add radar.
P-82E and P-82G originally to be Allison F36R/L V-1710-143/145 later changed to the Allison G6R/L also designated V-1710-143/145.

The F32 engine was two stage super charged with charged cooled after the engine stage (2 nd) supercharger, and Bendix SD-400 speed density (single point) injection. War emergency Rating was 2100 HP up to 4000 feet (grade 150 fuel required), 1720 HP at 20700 feet, and 1200 HP at 30000 feet. The G6 engines was however without the aftercooler but adding ADI (water) injection. The G6 was rated 2250 HP with water injection, and similar ratings at altitude as the F32..

The Bendix SD-400 was the Rolls Royce injection system built under license. Interesting it went on to have a long career in the big air-cooled V12s that powered the M46, 47 and 48 tanks.
Also note that the reliability of the G series engines left a lot to be desired

 

[Reluctant Poster]

A few corrections.
The Kestrels did not start with superchargers, in service, although designed for them. They were soon added but both supercharged and non-supercharged Kestrels were offered for quite some time during the same period. The Kestrel was even offered with two different compression ratios in the unsupercharged form depending on fuel and intended use of the engine. Instructions for the "F" engine said that full throttle was not to be used below 2,000ft in the moderate compression engine, below 3,000ft in the high compression engine or below 11,500ft with the supercharged engine. Later supercharged Kestrels offered different compression ratios and different supercharger gears.

The Buzzard was always supercharged although both compression ratio and boost were limited. Sales were also limited. Most airframe makers couldn't quite figure out what to do with it.
The type "R" was a considerably beefed up/modified buzzard and this is where the benefit of the racing program came in. Partially because it got RR into rapid problem solving and modification. The type "R" was not a group of slightly modified engines but a succession of modifications, some of which were major. In the series was the first use by RR of the sodium cooled exhaust valve.

What lead to the Merlin was the need for an in-between engine between the Kestrel and the Buzzard/"R". RR needed a large engine than the Kestrel but the airframe makers weren't quite ready for the Buzzard/"R"/ Griffon (all three used the same bore x stroke=displacement). With better fuels and the knowledge from the "R" racing program RR could build as smaller engine than the Buzzard in size while making nearly as much power. Granted the Merlin went through several design changes before they steadied down.
RR placed Buzzard/Griffon on hold in 1933. This derated R engine was run in 1933 but not flown in aircraft. In 1938-39 they started back up again with the reconfigured/smaller on the outside Griffon II engine first run in Nov 1939. This was the engine the RN was looking at in it's 1940-41 aircraft.

The racing program was useful to RR but it wasn't as direct connection that some might think. The 1931 racers could use up to 17.5lbs of boost and the record setting flight may have used even more. It used a different fuel blend than the trophy race. RR may have learned a lot about supercharge design compared to other companies at this time.

Supercharger design was not stagnant but with low octane fuel in service engines a lot of potential problems did not show up.

According to Schlaifer in Development of Aircraft Engines "The 1929 engine was changed principally by the use of a higher supercharger gear ratio and a larger air intake; still more power was to be got by running the engine at higher speed. This increased output meant, however, that changes had to be made in virtually every Stressed part of the engine. It was necessary to replace the blade-and-fork with articulated rods, and salt-cooled exhaust valves were used for the first time on any Rolls Royce engine."

 

[don4331]

RR placed Buzzard/Griffon on hold in 1933. This derated R engine was run in 1933 but not flown in aircraft. In 1938-39 they started back up again with the reconfigured/smaller on the outside Griffon II engine first run in Nov 1939. This was the engine the RN was looking at in it's 1940-41 aircraft.

Just to nit pick:
Isn't the de-rated R/Griffon (no version) the engine from '33.

Then you have the '38 request from FAA for an engine larger than Merlin (to accommodate additional weight of naval accessories - dingy, observer, wing fold, arrestor gear, catapult spools, naval radio), which results in the Griffon I of Nov/'39 with ~1,300hp.

But Merlin development is already on course to surpass that power/Air Ministry would like to see the engine in Spitfire. Which gets you the redesign resulting in the Griffon II which 1st runs in June/'40.

 

[wuzak]

Just to nit pick:
Isn't the de-rated R/Griffon (no version) the engine from '33.

Then you have the '38 request from FAA for an engine larger than Merlin (to accommodate additional weight of naval accessories - dingy, observer, wing fold, arrestor gear, catapult spools, naval radio), which results in the Griffon I of Nov/'39 with ~1,300hp.

But Merlin development is already on course to surpass that power/Air Ministry would like to see the engine in Spitfire. Which gets you the redesign resulting in the Griffon II which 1st runs in June/'40.

Griffon I was the detuned R.

Griffon II was newly designed engine starting in 1938 or 1939, which changed during development to allow it to be used in the Spitfire. The main changes, IIRC, related to the disposition of the accessories.

 

[wuzak]

"Development" doesn't mean "looks like."

It means similar design and/or construction. As for the Schneider Cup engines becoming the Merlin, Rolls-Royce might not have known what WORKED, but they likely had a definite handle on what DIDN'T WORK. Many things built from Legos don't look all that similar, but all are just a collection of boxes stuck together.

Many design features of the Merlin came from the Buzzard and the Type R engines. The sum of what Rolls Royce had learned making production and racing engines resulted in the Merlin and Griffon (basically a bored out Merlin type engine), particularly the Buzzard and the Type R ... according to many sources that are not me. I'm old, but I wasn't around when the Merlin was being designed.

Moreover, I have no stake in whether or not the claim is true. However it came to be, the Merlin was and is a good one!

One of the main design differences between the PV12/Merlin I and the Buzzard/R was the use of the "Ramp Head". This was like a pent roof style chamber/but angled, and owed its design to Rolls-Royce car engines.

The use of the Ramp Head meant that the PV12/Merlin had separate cylinder heads, whereas the Kestrel/Buzzard/R all had block and head as a single casting. Early Merlins also used a single casting for upper crankcase and cylinder blocks.

The Ramp Head did not live up to expectations, and there was difficulty in producing the single piece crankcase/block casting, so both were dropped and the Merlin was redesigned for the Merlin II. This was redesigned along Kestrel lines - single piece block/heads, separate crankcase, flat combustion chamber with parallel valves.

It was found that there were issues in sealing the cylinder liners in these castings, so the block and head were redesigned again, this time to have separate block and head. This was being done about the time that Packard was setting up to produce the Merlin, so they started with the separate block and head design.

The Griffon II was a vastly improved design compared to the Merlin. It had the bore and stroke dimensions of the Buzzard/R/Griffon I, but shared very little else.