Warbird Information Exchange

Hello,

I was wondering if anyone out there knows the current status of the Tempests under rebuild in the UK? If my memory serves me right, Kermit Week's Tempest is under active restoration still.

Thanks!

Ron

There was some news of this over on Flypast fairly recently. When the site's back up you should be able to find it.

Rob

Seems like the Tempest jinx is still working.

No aircraft even close to groundrunning yet. Has the engine of the one being closest (forgot the serial) already been worked on.

We do need a Tempest up there, round or inline doesnt matter.

Cheers

Cees

Cees
my understanding is that the Sabre engine is still awaiting re-build.
No Sabre-no Tempest V.

Let's face it. It's nearly impossible at present to get even a Centaurus to work, let alone a sleeve valve Sabre.

My guess is the first Tempest to fly will be in the big country across the pond--probably with a 3350 and several (many) years away.
Cheers
Andy

I've no idea what the problem is with Centaurus and Sabre engines but I guess it's the lack of parts and expertise.

The original problem with the Sabre was the actual sleeve valves. They had terrible trouble getting them right until Bristol were ordered to hand over details of their centrifugal casting process.

If you don't know anything about sleeve valves this http://www.sciencedaily.com/encyclopedia/sleeve_valve
gives a simplified summary. Some of the links on the page may help more but I haven't checked them.

I believe it was originally designed on that side of the pond by Willys-Knight in the twenties. The idea was used by Daimler in the UK shortly afterwards for a huge V12 which was apparently virtually silent but left a substantial cloud of blue smoke in its' wake.

The above may sound extremely knowledgeable but I'm about out now!

The Tempest 'jinx' is really more related to the actual value of the machines in the first place. No airworthy Tempest has ever come on the warbird market so it's no surprise that the type isn't that well regarded
yet. If they were Spitfires with a quite clearly defined value they would have been rebuilt years ago. As for the 'jinx' - well I was closely involved
in the rebuild of Tempest G-BSHW and the death of her owner David Martin whilst incredibly sad wasn't anything to do with his ownership of the Tempest. Similarily the death of Philipe Dennis who was her French owner was a heart attack. I hardly think there is a 'jinx' around the type.
The problem with spares for both the Sabre and Centaurus is that
there was no real need for the engine types once the Tempest V and II
left service hence they were mostly scrapped. The later Centaurus engines have very little commonality hence the reason why hybrid engines don't exist for them.
The first Tempest to fly will be undoubtedly Gerry Cooper's machine in the Midlands. Last picture I saw she was fully assembled on her wheels with engine installed. Gerry is having problems sourcing a couple of decent magnetos but once that is sorted I should imagine 2005 will see her airworthy.

Hi all
it's encouraging to hear about the Tempest II in the Midlands. I'll look forward to seeing that.
However, going back to sleeve valve engines and the associated problems. The sleeve valve engine was developed in Britain in the late thirties to try and counter the problems that engine designers were encountering when they tried to squeeze more power out of engine designs.
The designers started to encounter engine 'knock' and pre-ignition caused by the low octane fuels then available.
This was traced to conventional valves overheating and causing fuel ignition problems. The answer was to do away with conventional valves and the sleeve valve was what engineers arrived at after much trouble. In Government circles the design was promoted by Harry Ricardo the noted British expert on internal combustion engines and also by Roy Fedden of Bristol Aircraft. There was always a considerable amount of doubt in the minds of designers, engineers and scientist's about sleeve valve engines, for instance Dr David Pye, Deputy Director of Scientific Research at The Air Ministry was sceptical, remarking, "The single sleeve valve engine has been a sickly child ever since it was brought to birth and it might have better if it had been a case of infant mortality".

Of course, the pre-ignition problem in reciprocating internal combustion engines was eventually overcome by higher octane and better quality fuels, along with liquid-sodium-cooled exhaust valves leaving the sleeve valve engine as rather a dead end development.

I think personally and admittedly with hindsight that the whole program was a waste of very limited resources in wartime Britain and Bristol radials worked out in cost terms at almost twice as much per produced horsepower than a Rolls Royce Merlin.

Even Harry Ricardo himself in the end doubted it had been worth the effort writing later in life that " so many years... elapsed between... the research... and it's practical development... since the advantages of the sleeve valve were most apparent in the early days when we were using relatively low octane fuels."

I believe that sleeve valves were made to work by the traditional British method of getting a sick project to go--the simple expedient of chucking labour at it.
Not something many warbird owners have access to, whereas a Government in wartime can direct the whole R&D potential of a nations industry at something if it wants to.

As for the 'H' arranged Sabre engine, I'll make one final quote. This was taken from a memo written by a Ministry of Aircraft Production official written in 1945. By then the Sabre engine had been flying for four years in Typhoons and Tempests and was supposedly rectified of all it's problems.
"In the Sabre engine program, two incompatibles were brought together-an unusually poor producer and an unusually intricate article"
I have my doubts we'll ever see a Sabre powered aircraft fly again.
Of course, I'd be very happy to be proved wrong.
Cheers
Andy

Great explanation and history Andy!

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DBF

Thanks for the interesting info guys. The Typhoon/Tempest have always been favorites of mine. They are simply awesome!

Ron

Last question first -
Col - I believe: not in the UK (CAA design authority rules) perhaps in the USA... Rather like the Sea Fury question. Again, I think that Auz and NZ will be in the UK 'not acceptable' camp.



Sounds just as good a story as the 'cristals and Ommm folks' so called 'jinx' that affected the Carter / Tutankamen expidition. No jinx but it makes a good pub story.

David's excellent points are much more the real factors but don't get people going "Ah, yes, most mysterious. Mine's another pint of Champagne."

(Why, thank you. No, just a pint mug. The bubbles float up better I find.)

Scott, never mind these boring a/c, can we have a champers bottle emoticon please?

_________________
James K

"Switch on the underwater landing lights"
Emilio Largo, Thunderball.

www.VintageAeroWriter.com

Hi Rob
well not the Typhhoon but a Tempest II I think would take a 3350 in the same manner as the Sea Fury does. The 3350 fits well into the original Centaurus engine cowling on the Sea Fury so I would think the same could be accomplished on the Tempest. The Tempest would look better than the Sea Fury with a 3350 as the Tempest only ever had a four bladed prop (albeit one that rotated in the opposite direction).
I know there's at least one planned Tempest restoration in the States that'll most likely go down this road. It won't happen in Britain though as regulations won't permit it.
The thing that interests me about these restorations, apart from the engine problems is what restorers are doing about the Hawker tubular structure (similar to the Hurricane) that is used in part of the Tempest/Typhoon fuselage/centre section. Hurricane restorers have historically found the Hurricane an expensive and difficult aircraft to restore because of this structure. Hawker restorations in the UK had to produce all sorts of special tools and materials to restore the examples they have.
Any ideas,anyone?? The Sea Fury airframe was the point that Sidney Camm finally went to a complete monocoque structure.
Cheers
Andy

A little further research on the sleeve valve.

Sleeve-valves were invented by Charles Knight of Chicago in 1903. UK patent 1908 and US 1910. Many European licensees by 1913 but no real US interest until the Willys-Knight was introduced in 1914, also built in Toronto. Production ceased in 1932.
Looks like the Daimler I was thinking of was a relatively late one.

Andy,

It is because of the experience with Hurricanes that I believe all problems have been solved with Typhoon/Tempest Airframes. Their construction is very similar. There are also many parts/pattern aircraft to work from. I believe that we will see more of the Typhoon and Tempest (both MKV and II) in the next few years.

Hey guys, I'll try to answer part of this question..... Nelson Ezell and family do indeed own a Tempest... no secrets, just not well known.... they are not a group to "blow ones own horn", but you will not ever meet a nicer group of people in warbirds... Ashley Ezell tried to explain the issue with the sleeve valves..... You can take CNC machinery and mill new sleeves, and they work.....but not for long.... The original sleeve valves were spun. Ok guys be gentle with this next part as this may be completely wrong and I would love to be corrected, but here's a try. Say take a length of 4" diameter conduit and you wish to enlarge it to say a 6" diameter. You have this metal mounted to a spinning lathe head. Apply lots of pressure, heat. Then start forcing this spinning, open diameter end over a 6" stationery plug. You literally force the 4" opening to become a 6" opening. Ashley said simply, the technology will have to be re-invented to correctly manufacture new sleeves..... I know in conversations with Ellsworth Getchell, he always said the sleeves were the engines Achilles heel. The Ezell's Tempest has not been worked on in a while, they are always working on someones else's airplanes...... but yes, it is planned that the airplane will fly with a Wright 3350....... Alan

Not spun, centrifugally cast. The basic principle as I understand it is that the mould is spun as the molten iron or steel is added to it. This creates a very stable, even casting.
This was the trade secret that Bristol wouldn't part with until being ordered to hand it over. They were reputedly all made at a factory just down the road from where I live.