Typhoon aerodynamic tests

Back in the office after the holidays I did a quick search of the QinetiQ records and came up with references to a RAE Report from the Aero Department (Departmental Note No136) on the Flight test of Typhoon R7576 to reduce CO2 contamination.
There were also another 12 reports on Typhoon CO2 contamination and other serials mentioned in the titles were. R7595, R8925, R7617, DN409, EK271 and EK286.

If so why were the Sabre engined Tempests ( 80 of them) used as Target tugs by the RAF, the last ones converted in 1952, finally withdrawn in July 1955 ? Must have been some reason to use them for 10 years after WWII, well into the jet age.

Availability and performance would be my guess.

The fact is, as soon as the war ended, virtually all Sabre-engined machines were disposed-of out of hand, even many, many brand-new a/c (Very telling.). This was not the case with the Merlin (Or Griffon.) which continued into the Jet-Age.

If so why were the Sabre engined Tempests ( 80 of them) used as Target tugs by the RAF, the last ones converted in 1952, finally withdrawn in July 1955 ? Must have been some reason to use them for 10 years after WWII, well into the jet age.

According to Pete Pavey very detailed article “The war time link between Bristol and Napier” in the Rolls Royce Heritage publication “Sleeve Notes”, no 50, the Napier Heritage records indicate the final sleeve material I.e the Sabre V, VI, & VII (as a result of Bristol’s recommendation) was centri cast DTD 306 (En 40v) a 65 ton/sqin Nitriding Steel. The article confirms that Napier got priority on American production equipment.

Thanks for the Update on sleeve material. The Sabre V was the engine for the Tempest 6 and the Sabre VII was an updated version with ADI.

Sabre sleeves were finally made from nitrided austenitic forgings and machine tools (sunstrand centreless grinders) were diverted from the new P&W plant in Kansas that was to make the R-2800 C.

According to Pete Pavey very detailed article “The war time link between Bristol and Napier” in the Rolls Royce Heritage publication “Sleeve Notes”, no 50, the Napier Heritage records indicate the final sleeve material I.e the Sabre V, VI, & VII (as a result of Bristol’s recommendation) was centri cast DTD 306 (En 40v) a 65 ton/sqin Nitriding Steel. The article confirms that Napier got priority on American production equipment.

You live up to your name. 🙂 Thanks for taking the time to post!

I don’t believe it was the finish on the sleeves that was the major problem, it was distortion. All sorts of materials were tried and it was only when Bristol were instructed to reveal their methods the problem was solved. Bristol sleeves were machined from centrifugal castings which were very stable. When Napier switched to the same the reliability was transformed.
I was told some years ago that Sabre sleeves were made by GKN in Chesterfield and have no reason to doubt it.

Sabre sleeves were finally made from nitrided austenitic forgings and machine tools (sunstrand centreless grinders) were diverted from the new P&W plant in Kansas that was to make the R-2800 C. This gives an indication of the importance politically that was attached to the Sabre. So not only was Bristol beaten into submission but also the Americans.

But I repeat from above that there were many issues of assembly to overcome, and then of miss adjustment in service by fitters. By 1944 the engine was out of the woods and able to deliver its phenomenal power just as reliably as any other allied engine. A family friend now sadly passed away flew Typhoons and flew 60 missions from the beachhead in the same aircraft without an abort. But he was an exception pilot, and hated anyone else flying his aircraft. He never rated any of the piston powered aircraft as reliable, and was more than happy when the jet came along.

A production Sabre passed a 100 hour type test at 2500hp towards the end of the war, and the engines that went into the Tempest 6 were type tested at 3500hp. Finally a version with ADI was run at 4000hp. These power outputs were from std production engines rated at between 2500 and 3000 in service. These power outputs have never been matched by any other production piston engine.

The fastest Fury was powered by a Sabre, it was significantly faster than the Centaurus powered Sea Fury. By comparison with the woes that Wright Aeronautical suffered with the R-3350, the Sabre was a model of reliability.

http://naca.central.cranfield.ac.uk/reports/arc/rm/2603.pdf

Not high speed, no.

I don’t believe that the UK had a tunnel big enough to carry out high speed trials, but yes tufting is used in wind tunnels.

I don’t believe it was the finish on the sleeves that was the major problem, it was distortion. All sorts of materials were tried and it was only when Bristol were instructed to reveal their methods the problem was solved. Bristol sleeves were machined from centrifugal castings which were very stable. When Napier switched to the same the reliability was transformed.
I was told some years ago that Sabre sleeves were made by GKN in Chesterfield and have no reason to doubt it.

Tufts don’t necessarily relate to flight trials. The RAE had a large wind tunnel capable of mounting a full-sized airframe, as per reports on Hurricane and Whirlwind. No need for a Hampden to observe anything!

I think there is too little care has been taken above in separating the early years of the Sabre, where it did indeed show appalling unreliability, with the later years of its service. It is simply untrue that the Sabre was rushed out of service at the end of the war. The Typhoons were, but then so were other types including RR Merlin Spitfires. Postwar the Sabre Tempest became the RAF’s standard tactical fighter in RAF Germany and in the Middle East, with some service in India.

The Centaurus was delayed because of the redesign from forward-facing exhausts Bristol fashion to aft-facing exhausts following a study of the excellent engine/airframe integration of the Fw190.

The tufts may well have been to do with the shroud, but the shroud was there to stop CO re-entering the fuselage. Same thing, really. In the bottom line, my comments were only suggestions that I believe suitable to address known problems, not the only possibilities nor knowledge of the specific tests.

Thread creep or what ….? I too have seen figures that show that in 1945 the Sabre was more reliable than the Merlin but can’t lay my hands on them at the moment, so I will not bang that drum. I would, however, say that in common with many of these ‘pantomime’ threads (oh yes it was … oh no it wasn’t) the true deciding factors such as cost, production capacity, demand and timescales are often ignored.

So back to the originator’s query. First a health warning. Anything using the artwork in those early Profile publications as a source must be treated with caution. There are 6 other Typhoons on the same page as our tufted test aircraft and five of them exhibit serious flaws.

Some 30 years ago I transcribed RAE’s record cards on Typhoons. These detailed all flights, pilots, and gave a brief description of the tests carried out. There were 24 different aircraft used. Many could be eliminated for our purposes (if the published image was correct in its detail) and of the remainder, bearing in mind the arguments from my erudite fellow posters, one seemed to be the best candidate; R7589.

Although this had been one of 56 Sqn’s original equipment in October 1941 (US-U), it had gone back to Hawker for mods in April 42, which would have given it a canopy as shown in the profile drawing. It returned to Duxford and took part in ‘Jubilee’ with 266 sqn as ZH-T and was handed on to the first Typhoon bomber squadron (181) in October 42 with initial training on the type. On 7 Nov 42 it was flown to RAE but no tests seem to have been carried out until it had been to Langley for mods between 9 Dec 42 and 26 Jan 43. During this period it would have acquired the identity stripes shown in the drawing.

R7589 commenced ‘rudder control’ and ‘rudder trim’ trials on 6 Feb 43 flown by Flt Lt Moffet; these continued until 14 March 43. From 18 March the trials were frustratingly described as ‘Investigation’. Other pilots were briefly involved and from the end of May and through June the flights were all by Sqn Ldr Tobin. The flights went on until 1 October 43 and on 3 Oct R7589 was flown to Rearsby where it was broken down for use in Taylorcraft’s repair program.

There is also a note in AVIA 15/2601 (Typhoon accident file) that R7589 was used for ‘deflection of tail’ trials, during which it was photographed. Until someone can locate the original test report with photos of the tufted Tiffie, this identification remains a guess.

I always thought that the Sabre was made by a company called ‘Recalcitrant’ ?? 😮

At least that was always how it was written – “… the Hawker Typhoon, powered by the recalcitrant Sabre”……

I’ll get my coat………..

Ken

Interesting that the Typhoons were operating from 41 through to the end of the war, they were never phased out and had become quite reliable and very effective at ground based offensive and lower altitude aircraft fights. The Tempests never supplanted the Typhoon.

Rolls-Royce were indeed in a race to get their version of the hyper engine into the Typhoon/Tornado as the pre-eminent supplier for fighter engines. Their version of two Kestrel V12 engines married together in an “X” configuration using a single crankshaft had several problems, some were based on whip in the crankshaft, some on the yoke and blade conrod clamping bolts failing, piston rings and a heap of failures they had not seen before. The engine was not a straight marry either, it needed a longer crankshaft for wider main and conrod bearings, and added counterweights etc. It was 42L and finally produced 1980HP in the Model V in August 1941 giving (0.76HP/cuin) (2850rpm and 2613ft/min) vs Napier Sabre engine 37L – 2250HP (3700rpm and 2929ft/min) June 1940 (1.10HP/cuin) which became an embarrassment to RR. Hence I think it became their desire to wrap it up at the end of the war after purchasing English Electric engine manufacturing which included Napier.

As it turned out, the radial engined Centaurus from Bristol hardly got into the war – provided to two squadrons as Tempest II’s late in the war in 45. This engine was huge at 53.6L (cf RR Merlin at 27L) and had huge torque which became a problem in itself during taxiing but did have good HP. Version VII developed 2520HP in ’41 (0.77HP/cuin) (2700rpm and 3150ft/min).

Sorry – a bit off topic with comparisons…

I refer to the Merlin and Sabre because they were rivals within the RAF in terms of their application(s). The eventual disposition of the company (and their product) showed the intense rivalry that existed between the companies and their product. When you look at what happened to the industry after the war and some of the tactics that were used between rivals it is not illogical to say that the reputation of the Merlin was partly built up at the expense of the Sabres early issues (I am not talking about this being in recent times). Rolls effectively wanted the Sabre to disappear and made it happen.

I will leave it there….I am not going to get into posting reams of figures or information and besides I haven’t got the time, Typhoon items take up most of my spare time.

Fine Graham. My amusement only comes from the fact that it is one thing to say flutter relationships are known/understood and another to say that every learnt that! Flutter still catches people out. Sometimes it may be a modification or store or whatever that could have an undesirable/’foreseen’ consequence. I have my notes from 1984-89, but I don’t think we are really disagreeing. I have been out of fixed wing flight test for 18 years now – firmly entrenched in rotary wing!

I still don’t think the nose tufts are to do with CO….more to do with the shroud. I will dig out my old Tyffie accident report.

Have fun!

Really?

@DaveR;- It wasn’t my proposition that ‘the Sabre was more reliable than the Merlin by the end of the war’…it was yours…where is the evidence? 🙂

“(I am not saying that it doesn’t deserve every accolade it has, just not at the expense of the Sabre)”

Illogical.The Merlins reputation has never, ever, been at the expense of the Sabre…I think that’d be a new concept for most folks to start the New Year with. There were many, many other aero-engines that flew in the 1940’s. Few had the poor reputation of the Sabre…why single out the Merlin??? You can hardly blame the Merlin for the Sabres poor reputation.

I think the Sabre had it’s moment, it just didn’t last very long.:)

______________________

Anyway, we digress. My original question was to ask if any of the Typhoons shortcomings were transferred-across to the Tempest…

not to get into it too much further but I wonder where you got your information from re: reliability of the Sabre vs Merlin. There are many accounts that the Sabre would easily reach its 50 hours and I even heard somewhere that 100 hours was on the cards….I have heard many a criticism of the Merlin due to its reliability (or seemingly lack of), its ability to ditch its oil at a whim and it inability to reach its scheduled service. It was the sheer numbers of Merlins in use that allowed it to gain the reputation (I am not saying that it doesn’t deserve every accolade it has, just not at the expense of the Sabre). With modern rebuilds, tolerances, oils and knowedge all these engines are and can be far more reliable than they ever were before…plus the fact they are expensive toys they are very pampered!!

As for why they disappeared…ummmm….would it have something to do with a certain manufacturer buying Napier? I have heard that there was a big push by that certain company to ‘bury’ (almost literally) anything to do with the Sabre as there was more money to be made on the tails of the Merlin and the Jet Age and they didn’t want to have to deal with the Sabre (support, development etc) at the cost of the development of jet engines…cynical, me? never….

Wishful Thinking.

I’m not a statistician, but I’d be more than a little surprised if any figures can be found to support the idea that the Sabre was more reliable than the Merlin…. I’m very sceptical…:) but I’ll be wonderfully amused if wrong.
That the Sabre was clever, novel and unusual is well known. It was also capable of a very high power-output, it also had undeveloped capacity to develop much, much more power. (Doubtless it’d have been eve less reliable then….). However, the Sabre didn’t get it’s poor reputation for nothing. Nor is it’s mixed reputation something dreamt-up by latter-day ‘experts’, it is entirely contemporary with it’s service career. These opinions were formed by people very much at the sharp, or oily end. I suspect that admiration for the beast today may be a tad rose-tinted…..:)
Talking to Typhoon pilots years ago, they related that to get a/c started reliably for early ops, meant that the hard-pressed ground-crews used to run the a/c-up late at night to get them hot, then cover the cowlings with blankets & sheets to try and keep some heat in them so they’d start on the morrow. I think a cocked-up start at any time meant a long delay before another attempt could be made…. Pilots would not only have to use Oxygen from start-up, but they’d normally have to taxy-out and run up the Sabre without strapping-in, just so that they could reach to wipe-off the copious amounts of oil from the windscreen… Never a huge problem with Merlins unless they were getting very clapped. I seem to also recall mention that the cockpit used to get very hot.
There is no argument whatever that the Sabre was introduced to service before it was sufficiently developed.
There is also no dispute that some of the early issues were ameliorated – by dint of huge efford at every level from government right down to the erks on the flightline. Was it ever ‘sorted’..? I doubt it.
The fact is, as soon as the war ended, virtually all Sabre-engined machines were disposed-of out of hand, even many, many brand-new a/c (Very telling.). This was not the case with the Merlin (Or Griffon.) which continued into the Jet-Age. (In the case of the Shack’ until relatively recently.)
As for correlating the RPM at which the Sabre produced it’s power – it’s totally irrelevant, except in so far as the monster wore-out more quickly…..! (Most Napiers revved their balls-off.) The Sabre did everything at higher RPM. Tempest-Nut is under the misconception that the Sabres RPM equates to it’s performance, when speed’s merely a function of the engines power-output versus drag.
In the annals of piston aero-engines, it’s something of a truism to say that lower-revving, long-legged engines have been better suited – and much more reliable. Even over recent decades, there have been many high-revving geared aero engines that have fallen by the wayside. No names, no pack drill….;)
Despite all their novel features, Napiers aero-engines all seem to have been viewed with justified caution. All of which, quite reasonably, does nothing to lessen the interest they generate.