Earlier Tempest/No Typhoon

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About the early Allisons, I have the following:
1) V-1710-7: 1,259 lbs dry. NA-F7C Carburetor.
2) V-1710-9: 1,300 lbs. dry. Extended shaft for pusher prop.
3) V-1710-11: 1,300 lbs. dry. Similar to -7 except feathering prop. 6.23 : 1 S/C gear.
4) V-1710-13: 1,310 lbs. dry. Similar to -11 except extended shaft for pusher prop and AN-F7F1 carb.
5) V-1710-15: 1,305 lbs. dry. -11 with left-hand rotation.
6) V-1710-17: 1,350 lbs. dry. First "E" series engine for use with driveshaft and remote gearbox.
7) V-1710-19: 1,320 lbs. dry. Basically a -11 with PT-13B carb and higher S/C gear (8.77 : 1).
8 ) V-1710-21: 1,330 lbs. dry. Basically a -11 with PD-12B carb.
9) V-1710-23: 1,350 lbs. dry. Basically a -13 with PD-12B6 carb.
10) V-1710-25: 1,320 lbs. dry. None procured by AAF.
11) V-1710-27: 1,305 lbs. dry. First "F" series engine. PD-12G1 carb.
12) V-1710-29: 1,305 lbs. dry. Basically a left-turn -27 engine.
13) V-1710-31: 1,360 lbs. dry. Similar to -17 except PT-13B1 carb.
14) V-1710-33: 1,340 lbs. dry. Similar to -19 except PT-13E1 carb.
15) V-1710-35: 1,375 lbs. dry. Similar to -17 with gun synchronizer gear and latest distributors.

There's a lot more and if there is interest I can post the spreadhseet.
 
Nice figures on the Allison, Greg. It seems I was mistaken about my weight assumptions and that Allison document on Peril's site is mistaken or lacking in context (omitting reduction gear weight or some such?). Granted, I also don't know the context of the merlin or peregrine weight figures.



pbehn said:
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?
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This is the sort of thing that I suggested be passed off to Napier. You could even retain some of the core engineering development resources at RR for Peregrine design work while passing off all prototyping, testing, and production to Napier. (the Peregrine, Merlin, and Griffon had a lot in common design wise, so most of the added development work would continue to be useful and a 'Peregrine Mk.II or Mk.III' might end up skipping a few steps and go straight to a more or less scaled down Merlin XX or 45 -45 would be better for size/weight restrictions)

If the 3000 RPM limit is retained, such a miniature Merlin should maintain roughly 79% the performance of the full sized Merlin which would mean around 1160 hp WEP for a 'little Merlin 45' making the Whirlwind a 2300+ hp class machine. (it should be making that power before the V-1710-39 is entering service on the P-40D/E with 1150 hp military rating at 12,000 ft using 44.2" MAP or +6.25 psi -again, the V-1710 may have always been rated for 100 octane fuel but its official boost ratings were consistently very low for the first half of the war, but mind you those are official ratings and not representative of any inherent inferiority to the Merlin, Allison and the USAAF were consistently using far higher and more conservative standards than RR or the RAF)



Do bear in mind that that quote from Rolls Royce was from a letter (a persuasive essay if you will) strongly arguing for the discontinuation of Peregrine development and manufacturing (and possibly technical support) in favor of concentrating on the Merlin and Griffon. It was NOT a fair and balanced appraisal of pros and cons of the engine or potential for its future (or qualities relative to the Merlin itself) but focused on detailing all the disadvantages with minimal context and maximum implications towards inducing exaggerated inferences by the reader. It's not outright lying, but it's pretty well typical lying through omission inherent of most strongly worded persuasive essays.

It's records like that that historians and government officials (or consumers ... or anyone in the business world) must be wary of and be very careful to try to read between the lines and pick up on what's NOT being said. That letter is very clearly playing dumb and trying to maintain a state of selective ignorance towards the Ministry to better sway them towards what RR wanted. (admittedly for OTHER, obnectively valid reasons, but NOT for many of the reasons that article actually details -as they're faults shared by most if not all engines developed during the war and problems more severe on many designs than the Peegrine -likely not the Merlin at that point, but possibly the majority of non-RR projects in Britain and the majority of new engines in the US and Germany)

It's all relative, and anything can be made to look good or bad without blatant falsification if you want to sway opinion ... AND if you're smart enough to pull it off. (this is very, very common in technical history and something I've seen a lot of in the electronics/computer industry too)

And who better equipped to slander a product than its own designers ... all that detailed inside information at their fingertips to choose from.



In short: it's very unwise to accept that document from Rolls Royce at face value, it's misleading and manipulative and only really useful as an example of the state of business at the time. (and how capable RR's writers/editors' word craft was)
 
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Greyman said:
Were there specifics given? "Can't handle" casts a wide net.
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That is one of the problems with trying to look at the Peregrine and the Whirlwind.
I would note that the Merlin of early 1940, the "III" was only rated to use 12lbs for short periods of time and each use over 6lbs had to noted in the log book for evaluation by the engineering officer as to how it affected overhaul life. This also casts a wide net as not all engineering officers may have used the same standard/criteria. It may have been shaded by experience/judgement (or even the availability of spare engines?). Merlin XX was held to 9lbs for a few months after introduction and then cleared to use 12lbs in low gear only, It may have been cleared for 12lbs in both gears sometime after that although it eventually (Nov of 1942, over two years after the engine was introduced) went to 14lbs in low gear and 16lbs in high gear.
How much was due to more testing at teh factory and how much was due to operational results form the field (XXX number of engines made to overhaul after XX hours at 12lbs so maybe we can push a bit harder?)

Given a limited ability to test/develop a number of different engines or models ditching the the Peregrine was the right thing to do.
A lot of the criticism of the Peregrine/Whirlwind dates from around 1940 when it was just going into service. It was valid then (somewhat) but may not have reflected what the plane/engine ws doing in 1942/43.

Lets imagine what the reputation of the Typhoon would be if they stopped production after the first batch of 250? Early Sabres lasting 20 hours, tails falling off, etc. Not to pick on the Typhoon do the same thing to the P-47B, Stop after 200-400 of those were built (no model C) and look at the operational record of engine failures and crashes. Or pick a few others. First 100 FW 190s?

The heck with combat, just look at the engine problems and flight problems (anything from landing/take-off to high speed dives) especially in the first 15-30 planes.
Even with better engines the Whirlwind was too small to carry on to the end of the war and compete with late model Tempests, Late model SPitifres or P-51s or P-47s. It was way to small to ever become an "early Hornet".
 
The great Whirlwind debate usually functions like two sets of rabid religious preachers.

One set is convinced that, with the same resourcesas the Sabre and Typhoon you could get a chain of improving Whirlwinds from the base 1,600 bhp 1940 fighter to a 2 stage 100 octane 2,400bhp 1944 one. Extremeists of this view hold that Merlins would be better (and yes they could be fitted) or even a pair of Welland jets.

The others believe that the Whirlwind was not able to do these things but wildly accuse each other of differing heresies of what should have been an alternative. In a variety of forums and threads I have never seen one party persuade the other that they are right. I came to the debate uncertain of which might be the more correct.

I became a Whirlwind believer when it occurred to me that a 2,000+bhp 24 cylinder engine could be two 12 cylinder ones as an X(Vulture)H(Sabre) or 2 propellor Vs(Whirlwind)and all were valid and the latter the simplest and most reliable. I then went on to the minor heresy of equating the base Peregrine with Mercury or Perseus power releasing the radiators space for increased fuel and optimising for the low level ground role.

Whatever the merits of either argument I have carefully sought out and read the reports of the actual service pilots. In none of these have I found that they had a problem using other fighter aerodromes (bar Roborough and Hurricanes found that difficult), nor that they had concerns over the engines when using the pilot notes correctly and all seemed comfortable in taking on 109s and 190s other than the increasing performance of their opponents as years went by and the Whirlwind remained in it's 1940 form.

In balance, the more I learn of Westlands production (not quality) failings the more I understand why it was decided to ditch it. Pro Whirlwinders concentrate on improving it's performance but they might be better turning their attention to how one might have got a grip on Westlands actually getting the thing into service quickly. I wonder if one issue was that Lysanders were more profitable?
 

Just bought the Niall Corduroy book from Amazon looking forward to reading it.
 
Shortround6 said:
Even with better engines the Whirlwind was too small to carry on to the end of the war and compete with late model Tempests, Late model SPitifres or P-51s or P-47s. It was way to small to ever become an "early Hornet".
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Without a substantial redesign (ie more or less new aircraft with some related design traits) the Whirlwind wouldn't have developed directly into a late-war fighter like the P-38 did. The Typhoon didn't manage that either, though, and either a more advanced 'Super Peregrine' late war fighter or (IMO more realistically) more concentrated development on Gloster's Merlin engine twin engine fighter project would more likely make a 'earlier Hornet.' (though I wouldn't expect post-war hornet performance and likely a lower critical mach number)

In a scenario where the Saber is canceled, Hawker might pursue alternate single-engine large fighter designs and more aggressively pursue some of the advancements that resulted in the Tempest. With the vulture and saber dead that leaves the Centaurus to possibly pick up the slack if development could be pressed any further or (more likely) focusing on the somewhat lower power of the Griffon and/or considering a doubled peregrine derivative. (coupled merlin would be too big)

They could also still halt Peregrine production with the Mk.I but simply invest a hell of a lot more into Whirlwind orders sooner and have more peregrines built (and heavier testing and fixing of the -relatively minor, bu new engine standards- faults in fighter usage). If earlier operational testing of the engine and airframe had exposed some of the faults sooner, more modest Mk.II or perhaps Mk.Ia modifications might have been made to address those without real fundamental changes. (possibly addressing some, but likely not all of the problems like: throttle control linkage, lack of fuel system crossfeed, problematic wing slat operation, more extensive testing to properly define the structural limits of the peregrine at higher boost settings). I forget if the cannons had any jamming issues, but that should have been able to be addressed too. (usually it was due to mounts and temperature issues)

Honestly, a lighter Tempest (possibly even with similar fuselage and wing dimensions) would have fit pretty well with the Griffon 61 in 1943. (maybe well enough to actually displace Griffon Spitfire production)
 
Experimental armament installations:

L6844 - 12 .303" Brownings
another had a 37mm cannon

Hunting grounds:
#263 - Brest and Cherbourg Peninsulas and Western Approaches
#137 - the Channel and northern France
 
There was no 37mm canon. It is a trial installation of a 20mm. This has been mis identified many times over the years.

There was also a 2nd quad 20mm installation with the outer guns being mounted further back than the inner guns, the reverse of the pictures shown earlier. This set up did not have the three .303 guns mounted above.

I would note in the pictures presented earlier that the term "continuous feed" does NOT mean belt feed. The 60 round drum was an obvious limitation on the Hispano gun and simply building bigger drums wasn't really the best option. Several different belt feeds were being worked on (overlapping) as was the feed used in the Whirlwind set ups. This feed didn't use a belt but used a pneumatically powered magazine to feed the Gun (the Drums used a large spring), unfortunately ( or not?) the system used much more air in practice than in planning. On the ground a trial set up ran out of air and slowed down/stopped after 14 rounds fired. A much larger air bottle and compressor were going to be needed than originally planned and even then it was doubtful it could keep up with the demand of four such magazines. One of the Belt feeds was developed to a suitable state for operational use before much more time was spent on the pneumatic powered magazine.

The trial installations of this set up ( in the two different configurations) may have been test flown but not fired in the air. Ammo capacity was between 110-120 rounds per gun depending on which gun and in which configuration. While the Whirlwind may never have fired these high capacity ammo set ups the mock-ups and test flights mean it came lot closer than the paper proposals of the FW 187 or the Grumman XF5F and XP-50.
 
A combination of .303s and one or two vickers S guns might be good for ground attack/strafing and maybe some use as an anti-bomber weapon. (I'd think the quad 20 mm would be better there, though)

Larger drums also may not have been very practical, but a compromise for 90 round drums (possibly at the expense of some bulges in the nose) might have been a realistic compromise.
 
The Vickers S gun could certainly be destructive if it hit. It weighed about 2 1/2 times what a Hispano did and ammo was even worse. It also fired at around 100-140rpm depending on source but lets say about 20% of the rate of fire of a Hispano, very few rounds fired per attack.
 
I used to work with a guy who was crew on a 75 mm cannon-equipped B-25. He said the palne would lose about 10 - 15 mph for each shot! The ealry ones didn't have much recoil absorption and tended to oval shape the rivet holes after 10 - 15 flights. They were scrap after that, so only war-weary B-25's were so field modified.

On the early ones, the recoil could hurt you, so everyone had to be ready for a shot. It you were sitting with your head against a bulkhead, you could be knocked out! Doesn't sound like a mission for skittish people.
 
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The Vickers S is a fairly similar class of gun to the American 37 mm M4, though the feed system seems to be limited to a drum arrangement. Like the American gun, the value as an air to air weapons is somewhat limited and almost better used as a semi-automatic or short burst-fire weapon. It might have some use against bombers and other heavy aircraft, but otherwise it seems more useful for attacking heavy but lightly armored (or unarmored) 'soft' ground targets like the Hurricane IID tended towards. (I believe the effectiveness of those cannons was considerably better than rockets against similar ground targets, and the centerline arrangement of the Whirlwind should have favored that a bit more)

Carrying any more than two in the nose likely wouldn't be practical, one might even be more practical in spite of the more limited rate of fire (better if the ammunition capacity could be expanded at least a little) with supplemental .303 guns for strafing and possibly limited air to air use. (but I'm thinking more in line with a better alternative to both the Hurricane and Typhoon for ground attack, possibly even avoiding the use of rockets if the 40 mm shells continued to prove effective -far more accurate and much less of a performance hit)

Of course, similar armaments would have been useful on other twin engine fighters, but I'm not sure the Beaufighter would have fared even as well as the Hurricane IID in that regard. The Mosquito is probably too light and vulnerable to ground fire to be effective in a role like that, but Gloster's twin might have been more interesting. (putting a pair of M4 cannons on the P-38 might have been useful in a specialized fighter-bomber configruation, the high velocity M9 cannon -found to be too large/heavy to be satisfactory on the P-63- might have been useful in the P-38 as an anti-armor weapon as well)



As far as belt-fed cannons in production pre-war go, the 23 mm madsen comes to mind again. 300~400 RPM isn't stellar, but far better than the M4 or Vickers S while also higher in muzzle velocity (more in line with the .303), but the belt feed would have been the big selling point. The British didn't seem particularly interested for a variety of reasons, but the USAAC certainly was. It might have come to something if they'd secured a license for it before Denmark fell.
 
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Greyman said:
A self-driven belt feed was developed and successfully tested in a Beaufighter during June '41.
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Were the drums just a better fit to the pods mounted on the Hurricane IID?

An in that case, a combination of hispanos and a single Vickers S cannon might be a better combination for an alternate Whirlwind armament (or Gloster twin). Might be useful for interceptor work too, but seems like a lot of trade-offs between that and a pure hispano armament. (flatter trajectory, shorter time in flight, higher rate of fire, better effective range, but the 40 mm might be good for popping off a couple heavy shells at close range near the end of a pass right before breaking away from the target -really a similar case for the P-39's M4)
 
kool kitty89 said:
Were the drums just a better fit to the pods mounted on the Hurricane IID?
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Yeah the belt feed system was pretty bulky. The 'pods' on the Hurricane were just fairings that streamlined the guns, which hung under the wing. The drum magazine was inside the wing for the most part.

A 30-round, armoured magazine was developed in 1943 but the RAF were moving over to rockets at that point, and I'm not sure if it was ever used in combat.
 
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