Earlier Tempest/No Typhoon

[mexchiwa]

My question concerns the Hawker Typhoon/Tempest:

How early could a Sabre Tempest have been developed? How soon would Camm know that the Tiffie's wing would be a drawback at high altitudes, and what would earlier availability of the Tempest mean? Anyone have any thoughts?

 

[jtm55]

Hi All

@ Mexchiwa, here's a website that should help answer some of your questions The Hawker Tempest Page

 

[GregP]

The Sabre almost cost the plane it's production life as it was. I do not believe any earlier would have been possible unless a dedicated development effort could have started years before it did. The possibility of that is about zero or close to it.

 

[kool kitty89]

Putting higher priority on the Centaurus (and likely canceling the Taurus) and/or Griffon would have been much better options for timely development of a heavy single-engine fighter. Or they could have nixed all engine development other than the Hercules and Merlin and opted for a twin-engine heavy fighter/interceptor (fighter-bomber came later) instead. Or just pass Peregrine development and production on to Napier and keep the Whirlwind in production with added developments. (with up-rated engines and working wing slats -along with the improvements already made historically, the Whirlwind would have likely been a more capable fighter than the Typhoon, reliable sooner, and possibly developing into something more potent than the Tempest)

The Peregrine also seems like a good fit for Napier as it would fill most/any roles the Dagger had been intended for with far less trouble. (and should also fill most roles the Taurus was applied to historically -the Mercury, Pegasus, and/or Perseus could fill remaining gaps in that range along with imported R-1830s)


As for Hawker development of a single engine heavy interceptor, they certainly could and should have gone with a thinner, lower drag wing much sooner. Thick wings have engineering advantages (strength and internal volume) but were obviously bad for drag even without a proper understanding of the transonic flight regime. A scaled up Spitfire style wing would have worked as would something less extreme with the wing root more in the 15% thickness/chord range (like the P-40, P-39, Whirlwind, Fw 190). A larger version of a P-39 style wing would have fit rather well for that timeframe in general. The Spitfire's wing was 13% at the root, the Typhoon's 19%. (Hurricane was also 19% but used the less efficient clark Y airfoil compared to the variety of NACA airfoils used by the others above)

 

[KiwiBiggles]

I really don't think they could have done anything much earlier, given the amount of other work they had on. Hawker first began investigating a laminar-flow wing for the Typhoon in March 1940, which is pretty much the same time that North American started talking about the NA-73 (later P-51).

Presumably the delay between that time and the spec being issued (October 1941) and then the prototype flight (September 1942) can be put down to the huge load Hawker had at the time, with ongoing Hurricane development, and working the Typhoon up. Really, the only way to get the Tempest out much earlier would be to completely abandon Typhoon development some time in 1940, and transfer all Typhoon resources to the new design. That might get the new airframe out a year or so earlier; but you'd still be stuck with the troublesome gestation of the Sabre.

 

[kool kitty89]

I really don't think they could have done anything much earlier, given the amount of other work they had on. Hawker first began investigating a laminar-flow wing for the Typhoon in March 1940, which is pretty much the same time that North American started talking about the NA-73 (later P-51).

You don't need a laminar flow wing though, just one that's significantly lower drag than what Hawker used. Making it thinner would be the main consideration, but short of laminar flow airfoils there were still other NACA airfoils to use with lower drag (and lower lift) for potential better compromise in drag relative to internal stores capacity. Bell used the 0015 airfoil for the root of the P-39, that has zero chamber (symmetrical cross section) with less lift than the 2215 section used by the P-40 and more strength and internal capacity than the Spitfire's 2213.2. Unlike the Spit and P-40, the P-39 changed airfoils in the outboard portion of the wing, tapering to a 23009 at the tip. (the same high-lift 23000 series airfoil used on the Fw 190 and USN fighters as well as the Lockheed transports and the root of the P-38)

Scale up the P-39's wing by 23% (322 ft area) and you'd end up with similar wing loading on the Typhoon as the P-39D with significantly lower drag at high speeds and an 86% increase in internal capacity over the P-39. (likely a good deal more in practice given you tend to end up with proportionally more empty space when scaling things up -especially for fuel tanks)

 

[Shortround6]

The Typhoon's wing wasn't just a drawback at high altitude. It was a drawback at all altitudes. Unfortunately the boffins at the RAE were giving everybody bad information about drag and thick wings in the late 30s. Few, if any, British companies had their own wind tunnels. British also had some feild performance requirements (landing and take-off) that favored high lift (thick) wings. A few companies didn't believe the RAE and went their own way.
In 1937-40 a thin wing Typhoon might have meant a big wing Typhoon to keep the landing speed and take-off run down.

 

[davebender]

If RAF have a reliable 24 cylinder engine in mass production prior to 1944 it's likely to power more then just the Tempest.

 

[kool kitty89]

The Typhoon's wing wasn't just a drawback at high altitude. It was a drawback at all altitudes. Unfortunately the boffins at the RAE were giving everybody bad information about drag and thick wings in the late 30s. Few, if any, British companies had their own wind tunnels. British also had some feild performance requirements (landing and take-off) that favored high lift (thick) wings. A few companies didn't believe the RAE and went their own way.

Westland and Supermarine were both among the exceptions (ironically dropping back to a thick wing with the Welkin). Gloster went thin when working with jets and the F.5/34 was at least slightly thinner at the root and thinning out more dramatically at the tip than the Typhoon. (2218 to 2209 vs 2219 to 2213)

In 1937-40 a thin wing Typhoon might have meant a big wing Typhoon to keep the landing speed and take-off run down.

Hence why I suggested one of 322 ft area. The Hurricane and Typhoon also managed well above average wing aspect ratios in part due to the thick airfoil, but that lift/drag advantage only holds useful for take-off and low-speed cruise performance.

Going with the spitfire's thin wing route may have been extreme, but going along with nearly everyone else using airfoils in the 14-16% thickness/chord ratio at the root seems sensible. (or using a thick section only very near to the root for strength and internal space like the F4U and F2A did, among several others -the P-38 seemed to have more problems with that in spite of only using a 23016 section, but had other aerodynamic issues complicating matters and less of a drag problem and more critical mach problem)

 

[Piper106]

If RAF have a reliable 24 cylinder engine in mass production prior to 1944 it's likely to power more then just the Tempest.

If the Rolls Royce Vulture had been built essentually as two Peregrines with two crankshafts on a common crankcase, rather than historically (single crankshaft) they very likely would have had a 'reliable 24 cylinder engine'. A doubled Peregrine would have been a little bigger and little heavier than the historic Vulture, but I feel comfortable that the Tornado / Typhoon / Tempest would have handled it with ease.

 

[GregP]

The Peregrine was withdrawn from service in the Whirlwind after experiencing protracted development problems. Why on earth would they try to base another engine on one that they were were going to discontinue and remove from service?

 

[Shortround6]

The Peregrine had 2-3 major troubles. 1 was over heating due to improper settings of the flaps and exit doors. Solved with better training. 2 may have been leaks due to 100% glycol coolant, a fault shared with several other liquid cooled engines until the others switched to a water/glycol mix. 3, and probably the most troublesome was the problems with "Exactor" engine controls which worked using hydraulic pressure (low pressure, not connected to the normal hydraulic system) instead of rods and bell cranks or cables.
'EXACTORS to throttles, mixture and pitch controls. Prime before starting engines and again before landing. To do this move each lever to the full extent of its travel and hold at least 10 seconds. Return slowly. Repeat if necessary. Always move Exactor controls slowly'

Perhaps not such a good idea for a fighter engine control? They were used for pitch control on Whitleys and for engine and prop controls on early Sterlings and Sunderlands.

If someone knows of any other specific problems with the Peregrine please post.

 

[GregP]

Doersn't much matter what the problems were. They couldn't solve them in a reasonable time so the engine was withdrawn from service along with the Whirlwind. So my question still stands, why on earth would they base a new engine on one that ws being withdrawn due to protracted development problems?

Answer is obvious. They wouldn't and didn't, even in a what-if.

 

[kool kitty89]

Doersn't much matter what thge problems were. They couldn't solce them in a reasinable time so the engine was withdrawn from service along with the Whirlwind. So my question still stands, why on earth would they base a new engine on one that ws being withdrawn due to protracted development problems?

Answer is obnvious. They wouldn't and didn't, even in a what-if.

Most of the listed problems were with the airframe or control linkage mechanisms used in the given aircraft, not the engine and some of them were problems shared (to some extent) by the merlin itself. From what I understand, the main reason the Peregrine was dropped wasn't because of development troubles, it was because splitting production between Merlins and ANY other engine would severely compromise total engine output and cost MORE merlins than Peregrines (or Kestrels for that matter) than you'd get. And since production was canceled, further development was pointless. The fact the Whirlwind was the ONLY plane in production relying on the Peregrine also helped.

Honestly, there was probably equal motive to do the same to the Taurus except Bristol ALREADY had production divided among several engines and the Hercules wasn't as critical as the Merlin during the BoB. Still, most of the bristol engines were of the same bore and many of the same stroke- so canceling the Aquila and Taurus and focusing on the Mercury/Pegasus/Perseus size cylinders would have made sense and all the aircraft relying on the Taurus were fairly -or extremely- drag-heavy designs that could have soldiered on with Mercury, Pegasus, or Perseus variants. (given the state of affairs performance-wise when the Pegasus, Mercury, and Perseus stopped major development, it seems like the Mercury was the best off and the Pegasus's main advantage was its 2-speed supercharger -give that to the Mercury along with 100 octane fuel, and you'd close the take-off power gap a good bit)



Bottom line with the Peregrine is it should have been a good deal less trouble to get into reliable production through Napier and Son than the Sabre was, and further development might (I'd hazard a guess at likely) even be vaguely competitive with that of the Merlin. (I seem to recall Hooker contributing some to the Sabre's supercharger design too, and if the same improvements applied to the Peregrine that went to the Merlin, there's be a pretty straightforward path to the Peregrine becoming an 1100 hp class engine due to supercharger improvements alone -upwards of 1250 hp WEP if it went anywhere near as well as the Merlin 45)

The Vulture had more problems than the Peregrine and while it might have been less trouble than the Saber in the long run, probably wouldn't be as useful as a developed Peregrine. (I still say the Peregrine might have had a place on the likes of the Beaufort with better reliability and lower drag than the Taurus -probably the closest thing to a 'high speed' design that ever used the Taurus in production, the F.9/37 would count had it reached production)



Other than that, the best bet is to just build more merlins and cancel all designs not suited to that power class. (gloster's merlin engined twin interceptor/heavy fighter concept based on the F.9/37 might have seen greater interest in that case and probably would make more sense than trying to redesign the Whirlwind to house Merlins -being a much tighter design ... apparently more so than the 109 or Spitfire even)

 

[Shortround6]

We are back to 304 engines keeping 2 squadrons of twin engine planes going for around two years. And that is two years after the engines not only stopped development but had stopped production. Spare parts were how common?

The Peregrine's main fault was it was too small. So was the Jumo 210, the P&W R-1535 and the Taurus. Maybe a few others. Peregrine was 1296cu in. Lycoming had a 12 cylinder flat 12 of 1230 cu in. When they realized it was too small they doubled it into a 2470 cu in H-24.

This "what if" also seems to be proposing a double Peregrine instead of the Vulture which would
Put the timing 3-4 years before the Peregrine was withdrawn from service. Which happened to be well after the Vulture was withdrawn from service.

 

[GregP]

The Whirlwind went out of service for a reason and it wasn't the airframe. The Peregrine was a dead end without the potential for a big power increase and without enough power to make it as a fighter engine.

It ain't the cables and pulleys that did it. Pure and simple it was the Peregrine's lack of enough power to make a good fighter engine. It might have been able to run well at times, but the power fell short of contemporary fighter engines and absolutely wasn't going to get a lot better. End of reason for no more Whirlwinds.

The power was maxed and there was little to NO potential for significant further development without power. Had more power been avilable in the Pergegrine engine package, who knows?

Certainly nobody today. The best engine designers of the time couldn't get it figured out and development of these types of engines today is nil. So we are left to speculate, but I wouldn't bet too heavily on a Peregrine development since it never happened in the real world.

 

[kool kitty89]

Where are you getting this information? The Peregrine had less potential than the Merline, true, and it lacked the power to be useful as for new generations of SINGLE engine fighter aircraft, but the same was true for the small Bristol radials and a number of other designs (several of which -like the Taurus and Sabre- required a good deal of resources to get anything useful out of them and even then remained unreliable for much of their service lives).

So again, continued peregrine production was only a bad idea if it cost merlins ... if it cost Napier engines, and Napier wasn't going to shift to Merlin production, then switching production to Napier factories would make perfect sense. Otherwise the argument is just to build more Merlins all around. (which is a valid argument in its own right) Or I suppose setting up licensed production for the R-2800 might have been useful as well, and Napier did have experience with air-cooled engines. (and that seems like the only obvious 1800-2000 HP class engine around entering production by 1940, but who knows if other production problems would have developed there especially with differing cast vs forged cylinder manufacturing techniques)

Vulture development had more potential too, quite possibly more potential than the Sabre and more potential to become reliable sooner, but it would have cost Merlin development and production resources too.

There are often problems when transitioning from prototypes to mass production, both the Vulture and (to lesser extent) Peregrine suffered with such teething problems while the Saber was still yet to be tested. (the Merlin had a lot more time pre-war to work though any teething troubles)

This "what if" also seems to be proposing a double Peregrine instead of the Vulture which would put the timing 3-4 years before the Peregrine was withdrawn from service. Which happened to be well after the Vulture was withdrawn from service.

This itself is interesting. Coupled engine units have their own sets of problems but did work rather successfully several times and seems like a faster and safer bet than adopting the X arrangement. Dealing with the inboard exhaust tends to be a consistent problem there, and if nothing else you loose around half the exhaust thrust and gain some weight for added exhaust manifold ducting.

 

[Shortround6]

I believe the original presenter of this idea may have been suggesting a stacked pair of Peregrines? one inverted?

Lets not forget that the Sabre was essentially a 'stacked' engine. Two flat twelves geared together to use a common propeller and common supercharger/accessories. Granted they didn't make things easy on themselves by using paired cylinder blocks.

The phrase "teething troubles" although often used, sometimes leaves a bit to be desired. Is the one of the teething troubles a poor control system from cockpit to engine or a tendency to put connecting rods through the side of the crankcase? Now either one could end a flight and cause the loss of the aircraft and crew but which one would be harder to "fix". A French Hispano Radial had a "teething trouble" in the 30s. The gear case tended to come apart in flight with the propeller parting company with the aircraft. Some American engines had "teething troubles" in high altitude flight with mis-firing engines. This was solved by pressurizing the magnetos. The thin air at altitude not acting as an insulator like the thicker low altitude air.
You have "teething troubles" and you have fundamental problems/flaws, like the Armstrong Siddeley Tiger and Gnome Rhone 14K&M engines having only two main bearings on the crankshaft which limited power (both rpm and cylinder pressure) without a major redesign.

 

[Edgar Brooks]

So again, continued peregrine production was only a bad idea if it cost merlins ....

Which it would have; according to Rolls-Royce, continuing with the Peregrine would have cost two Merlins for each Peregrine.
With the better-engined Hurricane II capable of delivering the same ordnance, with a single Merlin, the Whirlwind/Peregrine was a dead duck.
The (almost) year's delay in the Tempest was caused by the C-in-C Fighter Command's insistence on it having a universal wing, capable of having various combinations of guns. Hawker struggled for a year, and finally got the go-ahead for an all-cannon wing.

 

[GregP]

I'm getting my information out of books on WWII fighters. WHere are you getting yours? Just one source is British Warplanes of WWII.

"While new new fighter prooved to have excellent performance at low altitude, it was at a distinct disadvantage when fighting-against-fighter combat began to move to higher altitudes, and it was necessary to restrict Whirlwind operation to a lower level where, for a short time, the type proved useful for light bombing operations and fighter sweeps. It had become obvious by 1940 that the type had its drawbacks, engine unreliability being high on the list, while high landing speed restricted the number of airfields it could use."

Almost all the other sources mention the Peregrine first among its faults. The first prototype Whirlwing flew 11 Oct 1938 and the last productione xample came off the line Jan 1942. The British knew the engine was unreliable as early as 1939 and enver solved the issues.

So I still wonder why anyone in the world anyone would base anything new on the failed Peregrine that had reliability isuues as well as poor altitude performance. If you're going to start an expensive new development, start with an engine that is a winner or with a new design, but don't start with an engine having known performance problems.

It's like basing a new car on the Edsel. Not even Ford was dumb enough to do that.