The 'ramp head debacle' makes RR to cancel the Merlin. What now?

[tomo pauk]

The fellow forum member posted in another thread:

The heads were trash but was the whole engine?
The Ramp heads showed up on the Merlin B, the first two prototypes did not have them, we are also using the retrospectoscope as we KNOW what worked and what didn't

For sake of discussion, let's say that what is noted in the title happens. Waht are the RR's options, RAF's options, Allied options past 1939?

Now in 1933-36 nobody knew how soon or even if 100 octane fuel would get there. They knew it existed, they knew it was possible and in 1935 they knew it cost about 10 times per gallon what 80 or 87 octane fuel cost. Maybe they could get the price down but until the price came down a LOT it was not a commercial fuel. They had 87 octane (and not every country used quite the same 87 octane).
going from 885-955lb Kestrels to 1600-1800lb Griffon X (experimental) is a stretch.

If we go with the weight figure of 1600-1800 lbs, perhaps power of ~1300 HP at 5 km might be expected for initial service use? Certainly worthy of the price increase, IMO.

 

[wuzak]

Go all in on the Peregrine?

 

[GrauGeist]

Perhaps Allison's V-1710 to the rescue?

Also, what time frame are you looking at, Tomo?

 

[tomo pauk]

Perhaps Allison's V-1710 to the rescue?

Also, what time frame are you looking at, Tomo?

For RR ant the British in general - from the late 1935 on. For the Allies in general - 1939 and on.

 

[wuzak]

For RR ant the British in general - from the late 1935 on. For the Allies in general - 1939 and on.

Given that Rolls-Royce quickly redesigned the engine, I can't see why they would cancel it.

But if they did, that would give them far more resources to work on the Vulture and Peregrine.

The Vulture may have been actually ready for combat by 1940.

 

[Shortround6]

They had gone through the Merlin C, E, and F with ramp heads and knew there was problem and were working on the Merlin G with the flat head in 1936, passed type test in Oct 1936, became the Merlin II and was in production in 1937.
RR built 25 of the Merlin Fs and 172 of the ramp head Merlin Is to have something to stick in airframes.
They built 1,283 if the Melrin IIs in 1937-39 so whatever substitute you want to come up needs to available in large numbers.
Merlin III was in production in 1938 and the main change was different propshaft so some of the continued Merlin II production was to suit the propeller supply.

Allison was useless for this scenario.
Not only was the Allison several years behind in development at this time they were still figuring out how make it in 1939. In fact it took Allison until May 1940 to build the engine in double digits. And you have the reverse of the Packard problem. You have to change all the drawings over to British standards (order of projection).

Edit;
With the Peregrine you have to redesign the Spitfire/Hurricane to be smaller and only carry 4-6 guns, Defiant won't work at all. Battle ??? two Peregrines? Whitley is doomed and the list goes on.
With Vulture you need to redesign the Spitfire/Hurricane to take a 2400lb engine. Basically design a Tornado/Typhoon equivalent and have in production in late 1938/early 1939.
A Hurricane with Pegasus engine would go far to rival the French for ugly

 

[tomo pauk]

With the Peregrine you have to redesign the Spitfire/Hurricane to be smaller and only carry 4-6 guns, Defiant won't work at all. Battle ??? two Peregrines? Whitley is doomed and the list goes on.
With Vulture you need to redesign the Spitfire/Hurricane to take a 2400lb engine. Basically design a Tornado/Typhoon equivalent and have in production in late 1938/early 1939.
A Hurricane with Pegasus engine would go far to rival the French for ugly

RR should go on with Buzzard+/derated R/'crude Griffon'. Going conservative, 1-stage 1-speed S/C, perhaps having about 1200 HP at 16000 ft, weight 1500-1600 lbs? 1500+ HP on 100 oct fuel?
Such an engine should work well on the Battle, Spitfire (380 mph) and Hurricane (330 mph).
Two-speed version, mostly for the bombers.
By mid-1940, a version with better S/C with 2-speed drive, that mimics power curve of the BMW 801C/801D? Plus an 1-speed supercharged version, call it Mk.45 for all I care, 1750 HP with over-boost at 10000 ft, that also gets installed on the Mustang for testing.
In the meantime, DH makes an gun-less bomber, with a bomb bay that is long enough to carry even a torpedo (and later the 8000 lb cookie), while Packard gets the deal for making the engines in the USA.

 

[Deleted member 68059]

I suspect they would have gone for the Griffon.

 

[yulzari]

Rolls Royce Exe.

 

[tomo pauk]

Rolls Royce Exe.

Use 24 cylinders when 12 will do? What are we, Napier?

 

[Deleted member 68059]

I don't think the exe would ever have been very viable, and would just have turned into another five year sleeve-development saga, especially
being air cooled in V12 format (meaning high variation in cylinder temperature from front to back).

 

[z42]

I think UK was very lucky in the timing of the Merlin, Hurricane, and Spitfire. If the Merlin is cancelled, I think there's a big chance they're caught with their pants down once the shooting starts. Adapting the Spit and Hurricane to the Peregrine is, I think, a no-go; they would just be woefully underpowered. And the Vulture is just too big and heavy. That basically leaves the Griffon, in particular the detuned R "Griffon I". So put that into production, to be replaced later by the improved historical Griffon II.

 

[don4331]

Peregrine Rules!

In '38, Merlin was making 1,030 hp while Peregrine was making 880 hp - a little over 15% less. But it is also ~ 20% lighter. Note: Making 15% less power, means it is also burning 15% less fuel

The 15% power reduction might be significant on Battle/Defiant as there isn't a lot one may cut without impacting airframe performance but implementing 2 speed supercharger probably gets them off the runway and keeps them as competitive at altitude as historic. RR just has to pay royalties to Farman.

For Spitfire/Hurricane, you move radiator from wing/rear fuselage respectively to under the engine ala P-40/Typhoon to maintain balance. Then there are several additional ways to bring power back up on Peregrine.

Sooner implementation of 100 octane - Peregrine was cleared for higher boost, but never rated for same
Hooker puts his efforts toward Peregrine - less power to supercharger/cooler charge = more output.
Increased rpms - stroke on Peregrine is ~10% less than Merlin; increase the rpms by that same 10% and power is very close to Merlin

An 1,000 to 1,250hp Peregrine (Single Stage); 1,300 to 1575 hp Peregrine (2 stage, 2 or 3 speed) isn't that different from equivalent Merlin. And would keep RR in the game until one of their larger engines was ready.

Lie, damn lies and statistics:

If it costs you 1M £ in development & tooling to build the Peregrine, 880 £ in materials ( 1 £ per hp) and labour equals material (for a quick reference) and you build 300 engines, each costs ~5,100 £
If is costs you 1.25M £ in development & tooling to build the Merlin (it is 25% larger) 1,030 £ in materials and labour equals material (same as for Peregrine) and you build 3,000 engines, each costs ~2,500 £.
The accountants say the Peregrine is more than 2X more (because the tooling is amortized over so few engines). And they cancel the Peregrine.
But if you build 3,300 Peregrines (replacing 3,000 Merlins + historic Peregrines), the cost for the smaller engine is >400 £ less per engine.

If you want alternate engine:

Does RR make a broad arrow engine using 3 Peregrine heads (1,800 cid); the Buzzard/Griffon I not being "in the queue" in '38 and Battle needing something larger than Peregrine?

 

[wuzak]

Perhaps Allison's V-1710 to the rescue?

In what way?

Allison steps up to supply the RAF with V-1710s?

Rolls-Royce adopts the V-1710 design and then develops it to their needs?

 

[Shortround6]

In what way?

Allison steps up to supply the RAF with V-1710s?

Rolls-Royce adopts the V-1710 design and then develops it to their needs?

Timing it all off.

Do in large part to the US chronic underfunding of US engines during the 30s the Allison development time was dragged for about 8 years.

1937 Allison has made 16 engines to date starting in 1932. RR has built over 200 Merlins, most are ramp heads.
1938 Allison makes 14-16 engines, 2 are altered while building so numbers are bit difficult to track
1939 Allison builds 46 engines for the year. Now these are divided between Turbo engines with propshafts out the back for Airacudas, turbo engines for YP-37, Spare engine for the XP-39. One, yes ONE, engine for the P-40 program and one engine for Bell XFL-1. Allison is constructing the buildings to make the engines for the P-40 order.

So the Allison is way behind in basic engine development. It is behind in manufacturing engineering (how do you actually make it quantity ) and until the Spring of 1939, the US doesn't even know if they want the prop out back or the prop in front or the prop out the front using a drive shaft.

Allison did a wonderful job sorting through that mess in late 1939 and building over 1178 engines while sorting out test stand problems and improving the basic engine (in part with money from the French and British contracts, British got 833 of the 1940 engines).

But the Allison might as well have been on the moon as far as sorting out any engine problems the British were having before 1939.

 

[GrauGeist]

In what way?

Allison steps up to supply the RAF with V-1710s?

Rolls-Royce adopts the V-1710 design and then develops it to their needs?

Why not?

It happened with the Merlin/V-1650.

The V-1710 redesign in 1936 saw a performance and reliability increase, as well as a higher horsepower output of 1,000 at 2,600 rpm during it's 1937 150 hour acceptance test.

It's entirely possible that had Britain adopted the V-1710, they would have addressed the supercharger issue like they did historically with the Merlin.

 

[Shortround6]

The Spitfire prototype weighed 5,875lbs loaded.

It carried 1585 lbs of "load" which leaves 4290lbs. empty with cooling fluid.
The "Power Plant" of engine, prop, cooling oil, fuel tanks, exhaust pipes etc was 2,035lbs.

We can do a rough estimate of the Peregrine or other other engine just based off the horsepower. 2 lbs per hp seems fairly close.

Better props weigh more

Yes the later Spitfires weighed more but in the prototype stage a major engine change can often call for starting over.

 

[wuzak]

Why not?

It happened with the Merlin/V-1650.

The V-1710 redesign in 1936 saw a performance and reliability increase, as well as a higher horsepower output of 1,000 at 2,600 rpm during it's 1937 150 hour acceptance test.

It's entirely possible that had Britain adopted the V-1710, they would have addressed the supercharger issue like they did historically with the Merlin.

So Rolls-Royce gets the V-1710 to develop?

 

[don4331]

The Spitfire prototype weighed 5,875lbs loaded.

It carried 1585 lbs of "load" which leaves 4290lbs. empty with cooling fluid.
The "Power Plant" of engine, prop, cooling oil, fuel tanks, exhaust pipes etc was 2,035lbs.

We can do a rough estimate of the Peregrine or other other engine just based off the horsepower. 2 lbs per hp seems fairly close.

Better props weigh more

Yes the later Spitfires weighed more but in the prototype stage a major engine change can often call for starting over.

Nothing you're say changes my belief that a Peregrine could be fitted to a Spitfire ala Jumo210 was fitted to a Bf.110 while Daimler-Benz got their act together on the 601. Peregrine-Spitfire and/or Peregrine/Hurricane buys RR time to redesign the Buzzard/de-rated R/Griffon I into the historical RR "big-block" V-12.

p.s. Ramp heads weren't the only Merlin issue; the combined head/cylinder block was also and issue - corrected for Merlin XX onwards.

 

[GrauGeist]

So Rolls-Royce gets the V-1710 to develop?

The Historical timeline of the Merlin and V-1710 is fairly close.


However, in Tomo's proposal, the Merlin failed to go introduction - so why wouldn't Britain take a look at Allison's engine for a potential license?

And it doesn't necessarily have to be R-R who gets the license, there were several firms to choose from, but R-R had Hooker, who was brilliant and resolved several issues with the Merlin and I'm sure he would have done the same for the V-1710.

Bear in mind that it was the USAAC's requirements that led to the V-1710's poor high-altitude performance.

I'm sure that the RAF would not do the same.