Earlier Tempest/No Typhoon

[Shortround6]

I saw you post above Shortround and find the reasoning sound. We still would have the maintnenace and overhaul chain for the Spirfires, etc. that had large numbers made, but your idea of 50 fighters for one squadrom for 6 months ain't bad at all. If that was the case, the Whirlwind did OK to stay solid for about 2 years with only 116 odd aircraft. I do NOT know if they sortied at the same rate as other fighters or were sort of lightly used. Anything I say along those lines would be conjecture.

I have two books that go through the operations of the two squadrons but since I have not read similar descriptions of other fighter squadrons I too, would be resorting to conjecture or speculation. It certainly seems like the Spitfires accompanying the Whirlwinds were used in much greater numbers but then the Whirlwinds were operating over a rather wide area and were escorted by a number of different Spitfire squadrons. Of course a History of Whirlwind No 263 squadron does not tell you what Spitfire squadron XXX was doing when it was not escorting Whirlwinds.
It was somewhat common for small groups of Whirlwinds to stage through (refuel and/or wait til the next day) a number of different airfields on some of these missions which countered the early argument that it's high landing and take-off speed would limit it to only a few airfields. Of course I have no idea how many of these airfields grew in size from 1939/40 to 1942/43 or how many had the trees around the field "trimmed" (cut down) so that argument can go both ways.

 

[GregP]

The Whirly came in at about 8,500 pounds or so empty and about 10,000+ pounds loaded, so the Thunderbolt of about a year later was half again as heavy. My bet is the fields got longer because the T-bolts were good planes, but nobody would ever accuse one of being a "short field" aircraft. I'd guess they used up more runway than a Whirlwind.

 

[Greyman]

Whirlwind take off figures (max weight)

early test +6.75 boost (10,072 lb)
Take-off run: 375 yards
Distance from rest to clear 50 foot screen: 710 yards

later test +9 boost (10,263 lb)
Take-off run: 325 yards
Distance from rest to clear 50 foot screen: 550 yards

 

[Shortround6]

Whirlwind take off figures (max weight)

early test +6.75 boost (10,072 lb)
Take-off run: 375 yards
Distance from rest to clear 50 foot screen: 710 yards

later test +9 boost (10,263 lb)
Take-off run: 325 yards
Distance from rest to clear 50 foot screen: 550 yards

The last set of figures are false, the engines would have blown up before the plane made it to the screen using 9lb of boost

 

[GregP]

A P-47M had a takeoff distance over a 50-foot obstacle of 1,800 feet or 600 yards when using 2,800 BHP, so if the Whirlwind had trouble getting on or off, the P-47 would have apparently never made it.

I haven't found the distance yet for the P-47D, which is more important than a P-47M.

The takeoff distance over a 50-foot obstacle for a P-47N was 2,350 feet or 783 yards and change. That was with less HP.

The Thunderbolt Mk.I over a 50 foot obstaclew as 1,000 yards!

I think we have our answer ... the fields got longer.

 

[Greyman]

I haven't found the distance yet for the P-47D ...

British Data Sheets over at P-47 Performance Tests give 1,050 yards for clearing a 50-ft screen for the Thunderbolt II (P-47D-25).

 

[GregP]

So I'd say that if the Whirlwind didn't fit into many British fields, they must have been very busy guys to get fields ready for the Thunderbolt!

They probably had to build the pubs first and then lengthen the fields. The workers had to have somewhere to go, after all. Perhaps there was a frantic "prefabricated pub" design contest and some modern technology was used to set them up all at exactly the same time.

The existing fields were giong to be pushed at 400 yeards and they needed 1,000+ yards, so the pubs were probably located some 300 yards from the end of the then-existing runways, but rapidly were approached by the runways as the T-Bolts' time to get there got near.

They could then use the remaining Whirlwinds to cool the beer by flying it up to 30,000 feet for a short stay. It wouldn't haul many bombs, but I bet it could haul 2 - 4 kegs of beer and still defend London. Natually, being Germans, the Luftwaffe pilots would never target a beer keg.

 

[Greyman]

... they must have been very busy guys to get fields ready for the Thunderbolt!

The Eighth Air Force of the US Army Air Corps had arrived in England. They had been preceded by the Corps of Engineers, who, to the amazement of the English, constructed air bases for them in three months. These bases included runways longer than any of those on the Stations in Bomber Command; interconnecting taxi-ways and hard stands for aircraft; living quarters, hangars and sundry out-buildings to American specifications. As this first rumble of American know-how and military capability was attracting England's attention, I made myself unpopular by reminding the English boys that it had taken the union-restricted Works and Bricks Department more than six months to build a twelve-by-twelve brick 'sh** house'.

- Hugh Godefroy RCAF

 

[Edgar Brooks]

It is statements like this that raise the hackles of "defenders of the faith,".

I'm fully aware there are people, in this world, who are completely devoid of a sense of humour; that's for them to live with, not for me to tiptoe around their sensibilities.

What is meant by "Peregrine could not run on 100 octane on a regular basis (whatever the Whirlwind Pilot's Notes say.)"

It means precisely that; Rolls-Royce said that the Peregrine, as it stood, could not run on 100 octane on a regular basis. The engine could run on 87 octane, at around 6 psi, but, on 100 octane, if 9 psi was used, every instance had to be noted in the engine's logbook.

Does that mean that you could not put 100 octane fuel in the tanks and fly it for dozens of hours while never exceeding 6lbs boost

What would be the point? Why waste precious 100 octane, when you can get the same results with 87?

The Phrase uprating the engine to take 100 octane 100% of the time is also rather confusing.

Can't see why; if use of 100 octane, at its higher boost, caused damage, the Air Ministry are hardly likely to look favourably on a flood of damaged engines returning to Rolls-Royce for repair.

Early Merlins could only use the extra power/boost that 100 octane fuel allowed for brief periods of time and in emergencies yet seemed to run for hundreds of hours on 100 octane without self destructing.

Rather shows the wisdom of concentrating on the Merlin, instead of the Peregrine, doesn't it?....

Now maybe the Peregrine was fatally flawed (or had multiple flaws) that prevented the use of even 9lb boost let alone 12lbs. Or maybe it needed a new crank, rods, crankcase, cylinder blocks, etc to get to 16-18lbs of boost. I have no idea.

Then why keep on about how it should have been retained?

Each engine is different but if you could run Bristol Mercury engines at 9lb of boost for short periods there must have been something really wrong with Peregrine if it could not. An strangely, what ever this flaw or collection of flaws was, it never gets spelled out or listed in commonly available materials (books, magazine articles, internet sites).

Maybe the authors should spend time looking at the files held in the National Archives and by the Rolls-Royce Heritage Trust

 

[GregP]

Thanks Greyman,

That was a joke ... but I appreciate it anyway.

 

[Greyman]

Can't see why; if use of 100 octane, at its higher boost, caused damage, the Air Ministry are hardly likely to look favourably on a flood of damaged engines returning to Rolls-Royce for repair.

Is there any reason to believe the Peregrine I couldn't handle +9 boost as well as the Merlin III could handle +12?

 

[Edgar Brooks]

You either believe Rolls-Royce, or you don't.

 

[pbehn]

You either believe Rolls-Royce, or you don't.

I thought the difference between using for a short time and being able to use for unlimited periods was the thousands of hours proof testing that Rolls Royce would need to do. Wasnt this development the reason why the peregrine was abandoned?

 

[Edgar Brooks]

Testing times get no mention in the files; the Air Ministry reported to the government that Rolls-Royce had said that the engine would need so many modifications it would be a virtually new engine. They also said that it could only be built at one factory, and that each engine would cost 2 or 3 Merlins, or would mean long delays to the introduction of the Griffon.

 

[Greyman]

'So many modifications' to achieve what, specifically?

 

[Edgar Brooks]

An engine capable of handling 100 octane at all times.

 

[Greyman]

Were there specifics given? "Can't handle" casts a wide net.

 

[pbehn]

At various stages the Merlin couldnt handle many things. After many hours of testing and modifications it eventually could handle them. There were many versions of the Merlin eventually producing 2030 BHP the engines in between the PV12 and the 133 could all be termed "different engines".

The UK was facing an enemy with the Bf109 powered by a 35.7L swept volume engine, the Merlin was only 27 L. Rolls were having to run to stand still against the Bf 109 swept volume advantage, souping up the Peregrine to the same performance of a Merlin just to keep the Whirlwind in production would be a massive folly.

 

[kool kitty89]

Of course they preferred the Typhoon. A single engined fighter with 2000BHP v a twin engined fighter with 1,600BHP. And eventually they were correct, the Sea Fury was the ultimate progression of the Typhoon/Tempest/Fury as up there with the best of piston engined fighters. Any theoretical progression of a peregrine twin fighter would be eaten by a Tempest or Fury.

I cannot think of an example of a twin fighter out performing a single in the front line. There is much debate here about the P 39 .....but in Europe it was not a success.

The Fury came too late to be useful in WWII and the Tempest itself was only useful late war. Compared to the P-38 (which I assume you meant rather than P-39) the Whirlwind had MANY fewer teething problems and with the level of support the P-38 got, would have been a highly competitive fighter far sooner than that American twin AND without the same issues of being much larger an dheavier than single engine counterparts or having poor roll response without boosted ailerons. (IMO the P-38 should have gotten spring tab boosted ailerons from the start like the F4U -no hydraulics needed- ... a stick might have offered better response and leverage than that yolk too)

Aisde from that you ALSO had Gloster's twin designs and Supermarines ones among others that went unexploited and left on paper while the Typhoon got forced along with poor high speed aerodynamics and a very troubled engine.

The Typhoon had NO engine in reliable mass production in 1940 ... or 1941, the Whirlwind did in 1939.

I'm also not talking about super powered Merlin or Peregrine engines, I'm talking about the existing 800~1100 hp class engines of 1939 (1310 hp WEP in the BoB -I'm sure higher on RR bench tests) that had SOME obvious potential for growth and at very least could be expected to maintain existing production quality. In 1939 the Peregrine was likely better off than the Taurus in reliability terms as well.

Banking on new, unproven engines is a massive risk that twin engine fighters consistently avoid using existing lower powered engines to achieve their performance.

The Sabre was retired as soon as the war ended but the Spitfire and the Griffon served for years after

The Griffon and Merlin deserved the most of RR's development attention for sure and an earlier Griffon would have been more useful than the Peregrine BUT there's still a great deal of engineering commonality between all three engines so it's not so clear if canceling any one earlier or developing one more aggressively earlier would have helped. The Vulture shared less in common design wise and would be a more rational design to drop early on.

It might have been good to compromise with a rationalized mass-production capable Rolls Royce R that omitted some of the refinements the Griffon targeted (including smaller frontal area) in favor of quicker time to production.

The Taurus was showing problems early on that had some commonalities with the Aquila, I believe, and some new problems on top of that while the Hercules was developing more smoothly and in a more useful power range, so even in 1939 and 1940 there was plenty of rational reason to kill the Taurus and focus on the Hercules.

The problems with the slats were only identified much later, after the type had been operational for some time. I imagine it was a case of pushing things a bit farther in combat than in initial testing.

For example, while testing the Whirlwind, the A&AEE listed a limiting dive speed of 420 mph IAS. The official Pilot's Notes list a maximum diving speed of 400 mph IAS.

The CO of 263 Squadron, however, said they had dived them to 460 mph IAS.

Had the Whirlwind been deployed more aggressively sooner, that should have been exposed sooner as well (enough to get worked into the Mk.II I'd think). As it stood, it might have made sense to use a locking mechanism that could be applied and removed depending on the mission profile. Fighter-bomber loads would seem more worth the risk for the improved take-off run, while fighter patrol and interception duties would make more sense to keep wired shut. (if they had more planes, having some wired shut and others left unlocked would probably be easier)

Now maybe the Peregrine was fatally flawed (or had multiple flaws) that prevented the use of even 9lb boost let alone 12lbs. Or maybe it needed a new crank, rods, crankcase, cylinder blocks,etc to get to 16-18lbs of boost. I have no idea.

But there is a world of difference between cruising at 7-10lbs of boost (running at 100 octane levels) 100% of the time and cruising at 2-4lbs boost and using the 7-12lbs boost for take-off and emergencies.

I suspect RR might have been using excessive caution with the Peregrine due to the very limited number of spares and spare parts, somewhat like was discussed for the V-1710 recently. (though more legitimately extreme)

Now before I get accused of saying Rolls Royce was lying, IF Rolls Royce was saying that in order to make 100% use of the potential of 100 octane fuel then they could very well have been right. To make full use of 100 octane would require the engine to operate at 16-18lbs of boost and would require quite possibly a new supercharger

The exact same thing is true of the V-1710 at the time, both the -39 and especially the older -33 (more contemporary with the Merlin III and Peregrine). They required 100/100 octane fuel, but ran pretty much entirely in envelopes 87 octane likely would have been fine with the possible exception of running extremely lean. (most 87 octane fuel was much closer to 87/100 than 87/87) American 100 octane was of course chemically very different from British mixtures with almost no aromatics and considerably less lead.

The -33 (C-15) ran at Military/Emergency power of under +4 psi boost (37"), though overboosting (which that official USAAC/Allison chart on Peril's site shows) clearly showed potential for going all out at sea level and pulling around 66" (+16.6 psi) and nearly 1700 hp at 3000 rpm without using ram. Detonation was not a limiting factor there, but engine structural integrity was. Allison warned that pulling max boost on the later F3R (39) and F4R (73) could destroy the engine (in reality I believe it was the F3R more seriously vulnerable and Allison was always a bit more cautious than Rolls Royce with both boost and limiting RPM).

I'd expect the Peregrine to be in a similar situation to the V-1710-33 and possibly similar in ability to use 100 octane fuel for leaner, more efficient cruise. To get a 1200 hp class engine out of the Peregrine, it's probably going to end up at nearly as heavy as the Merlin III. THAT might be a problem for the Whirlwind: if the peregrine saw the same weight creep as the Merlin, and it was truly as tight a design as some authors imply or claim, that would mean it would be more difficult to adapt to new engines than the Spitfire. (honestly, the Peregrine to Merlin III swap shouldn't have been much more trouble than the Merlin VII to XX swap for the Spit III let alone the Merlin 45 to 61 transition ... or the Griffon)

Still, it should at very least tolerate a Merlin III => Merlin 45 style engine performance upgrade optimized around minimal modifications like the Spit V was.

 

[kool kitty89]

Hi Kool Kitty,

You can reckon the V-1710 at 1,480 pounds. When we ewere building them, they were all just under 1,500 pounds with starter before adding oil for run -in. Of course, we had a run-in platform that was a Ford F-350 truck with engine mlont, radiator, oil tanka dn pump, etc. I am not sure of the all-up weight of an Allison V-1710 with radiator and oil tank ... depends on the radiator and oil tank.

Yes, but I'm trying to discern the dry weight of the early-war (and pre-war) C-series engine like the P-40B/C and XP-38 used. The V-1710-39 (F3R) manual lists its dry weight at 1310 lbs, I'm sure later engines gained more weight from various strengthening (aside from added weight from larger radiators and oil+coolant header tanks) but I'm looking for the EARLIER engines. Most simplified museum sites (including the NASM) list the standard generic vague V-1710 weight that's almost certainly inaccurate for the V-1710-33 (C-15). I'm fairly certain the C-15 is significantly lighter than the F3R or Merlin III and XII, but I'm just not sure on exactly how much.

My thoughts were that the Allison ws a GREAT engine down low but suffered without the turbo when things got higher than 15 - 16,000 feet ... exactly the weakness the Peregrine had. So ... the turbo would address the altitude issue. The resulting aircraft would probably have been faster than the Peregrine-powered bird but, without the turbos, would probably start to suffer in the mid-teens verus a 2-stage S/C day fighter.

The V-1710-33 was actually pretty favorable performance/size/weight wise to the Merlin III, but the Merlin saw both more aggressive boost increases and general abuse of the engine along with much more attention to the supercharger with the 2-speed version of the older supercharger to the vastly improved Merlin XX and 45/50 series one to the High alt 46 to the 2-stage liquid intercooled one that had a lot of advances even Turbo'd Allisons lacked. (GE was behind in compressor efficiency and intercooler design while RR was at the cutting edge -they benefitted from RR compressor experience for the I-16 and I-40 jets too)

Fix the aerodynamic issues with the V-1710's intake manifold and lift the max RPM and boost limits and the F3R should have been on par with the Merlin 45 is not superior. You don't even need the 9.6:1 supercharger, just boost WEP to 3200-3300 RPM and that should cover it.


Edit:

I saw your post above Shortround and find the reasoning sound. We still would have the maintnenace and overhaul chain for the Spirfires, etc. that had large numbers made, but your idea of 50 fighters for one squadrom for 6 months ain't bad at all. If that was the case, the Whirlwind did OK to stay solid for about 2 years with only 116 odd aircraft. I do NOT know if they sortied at the same rate as other fighters or were sort of lightly used. Anything I say along those lines would be conjecture.

Agreed. The biggest problem with the Whirlwind was it was ordered in too small numbers with production priority too low from the start. More Whirlwind orders means more peregrine orders, more spare engines AND airframes to work with, more spare parts, more potential canibalization of parts even if production ceased, more planes flying sooner and more in-service testing to catch faults/flaws earlier, etc, etc.

Put the Whirlwind on par with the Spitfire and Hurricane priority wise (and ahead of the Defiant and Lysander) and it would have unquestioningly have been more useful to the war effort even if it ended up dead in the water production wise before 1942. Cut Lysander production to a few hundred aircraft and push Whirlwind orders over 1000 at least once war breaks out. (A modified fighter-bomber Gladiator with variable pitch prop might have been better than the Lysander in the close-support/attack role, but that's another matter)