De Havilland PS26-6 Gyron

Why 0.45 Gy.Jr?

1954: “stand-off” bombs. Blue Boar chopped, Blue Steel, 100nm. range, initiated. More range for a successor would need a light turbojet. RAE was leading all this, as MoS had no faith that industry could cope with its aeroplanes and take on long range ASMs. (ex-Power Jets) NGTE saw DH Gyron as lighter than, say Olympus; MoS saw DH as more “spare” than ASM/Bristol/RR. The down-size was driven by the ASM berth (funding); Blackburn then plugged it into NA.39 hole. In Bristol T.188, as wet PS.50, it soon so diverged as to be a discrete type.

What did De Havilland have in mind when it decided on scaling down to 45% to produce the Gyron Junior, why not another figure?

The wing is at Cosford, the tailplane I think may have gone missing.

The Type 188 intended role was to;-
1 – Prove the viability of using stainless steel as a primary airframe material. i.e. obtain a practical structural mass fraction
2 – Prove the viability of the supersonic aerodynamic configuration intended for use on the Avro730 – i.e. obtain a practical supersonic drag and stability characteristic for the long slim twin engine configuration
3 – Investigate the thermodynamics associated with sustained supersonic flight – i.e. obtain practical experience of the kinetic heating and thermal stabilisation.
4 – Act as a flying test bed for potential supersonic engines

With the P1121 does anyone know if the Wing and Horizontal Tailplane are at Cosford? These items were reported to be at Cranfield.

Percentage completion or always a little difficult to estimate and interpret. A better rule of thumb is that, on most first of type programs, there is a year (give or take a few months) between putting the main airframe transport joints together and first flight. So I would have said the P1121 was 12 -14 months from first flight.

Can someone please educate me? What, exactly, was the intended role of the Bristol 188? I always thought the ‘Flaming Pencil’ was intended purely as a research airframe.

Whilst we are on the topic of engines and never weres/could have beens, does anybody know what the intended power plant for the Vickers type-581 was?:confused:

Thanks in advance sealordlawrence.

I believe it went to Cranfield to be used as an instructional aid.

Interesting stuff there Vega, thanks.
I didn’t realise the fusalage section was still extent, lets hope it stays preserved and maybe displayed.
The amazing thing is out of my window I have a view of an unused and incomplete Typhoon fusalage, it looks strikingly like the P.1121 fusalge in that photograph.

I always found the survival of the P.1121 fuselage weird, what on earth did anyone think they were going to do with it? Especially when you consider that the Supermarine Type-545 (considering this was the last aircraft from the company that made the spitfire it is truly weird!), which was far more complete than the P.1121 at the time of cancellation seems to have disappeared without a trace! One thing I will say is that the P.1121 legend owes alot to the internet I dont think it would be so well remembered if it was not for that and I mean that in a good way, people have been able to have serious discussions about where things went wrong and where they went right, the P.1121 could have been the latter.

Interesting stuff there Vega, thanks.
I didn’t realise the fusalage section was still extent, lets hope it stays preserved and maybe displayed.
The amazing thing is out of my window I have a view of an unused and incomplete Typhoon fusalage, it looks strikingly like the P.1121 fusalge in that photograph.

A mock-up was built and photographs of this are sometimes claimed to be the prototype – some sources claim the prototype was around 85% complete when the plug was pulled but I can only assume this was as a private venture because the government had shown an utter lack of interest.

Figures vary from about 60% to 85% depending on the source.

Its not true to say there was “an utter lack of interest”. Its fairer to say Sidney Camm was unofficially encouraged to spend Hawker money on it, as an insurance policy should F155T fail to get built.

is it me or does the Bristol 188 look remarkably similar to a certain American design we all know and love? Could this be another case of American strong-arming of the UK Aerospace industry?:eek:

Not likely.

The concept of the Gyron engine was quite sound. Frank Halford deliberately chose a lowish pressure ratio, as it allowed the use of less exotic materials in the construction and made the design rugged, cheap to build and maintain, typical virtues of De Havilland engines. He realised that, for high altitude Mach 2.0 flight, the intake would be greatly adding to the compression of the engine and allow large thrusts to be generated by a relatively simple design. Its not a dissimilar approach to the R-15 engine of the MiG-25, or the Atar engine of the Mirage III. The Olympus got greater fuel efficiency though its higher compression ratio, but its performance above Mach 2 would have been hindered by turbine entry temperature limitations.

Hawker believed that the P.1121 prototype with the Gyron would be able to exceed Mach 2.5 for short periods, perhaps even going as high as Mach 2.7.

A production P.1121 would probably have used an Olympus engine for good all-round performance, sacrificing the very high speed capability for more range and performance at lower levels, or a Conway with reheat if strike had become the primary mission.

This section of the P.1121 prototype is stored at Cosford now as stated above.

Thanks for posting, my picture is from a different angle, but it more or less shows the same. Note the flat panels/gaps in the side of the fuselage just below and behind the cockpit, these were for rocket packs, the P.1121 would not have had a gun. A decision which in my opinion would have been reversed had the type ever made it to service.

This section of the P.1121 prototype is stored at Cosford now as stated above.

Which begs the question, why didn’t they put an early Olympus into the 188?
Even one of the more powerful reheated Sapphires or Avons seem a better proposition than the Gyron Jnr.

The Bristol Type 188

The 188 had four principle problems;-
1 – Mass growth during airframe design. It’s original OWE was planned to be about 20klbs but as the grim reality of using stainless steel became apparent this crept up to about 30klbs. Given the max flying weight (about 42klbs) is capped by the strength of the structure so such a large increase in OWE becomes quite a difficult problem to manage. The only solution, given by this stage the aircraft had been built, was to limit the fuel carried (only about 6-7klbs of fuel was carried with the remained being the flight data recording system). Hence in terms of fuel reserve, the aircraft was technically in a state of fuel emergency pretty much a minute or so after take off.
2 – The Gyron Jr. DGJ 10 was not optimised for fuel consumption (e.g. SFC tuned by root cord cut backs e.t.c). By the later stages of the Gyron Jr. development all the clever guys who designed the engine had left the project and the remaining technical staff struggled just to provide the basic flight clearance.
3 – The Gyron Jr. was very sensitive to compressor face flow disturbance. This presented a particular problem for the linear conical aero-spike intake control system (in itself not the best solution to the supersonic air-intake). Hence the engine would frequently surge when running much above 1.5 Mach.
4 – The project was cash strapped – Technically the engine nacelles and intakes had been sized to take a number of different engine types (note – this actually exacerbated the problems in points 2 and 3 above) but the budget was well overspent by the flight test phase. I have seen a very modest proposal to equip one of the aircraft with in flight refuelling but even this was rejected on costs grounds. This was a very low cost route to addressing all of the above issues and acquiring the original data objectives.

Did you know;-
· The aircraft was designed to be flutter stable up to 2.8 Mach but there was thought to be some conservatism in the prediction methods and hence it was hoped 3 + Mach would be possible when flight test results were analysed.
· The aircraft original flight test point requirement was only to perform about 10 minutes above 2 Mach, or 6 minutes above 2.5 Mach
· An enlarged tactical reconnaissance version was proposed with a radius of action of about 600 miles but was never taken up
· Following the aircraft’s display at Farnborough the Shah of Iran commissioned a study into an intercept version and a brochure was produced by Bristols
· The 188’s design take off weight was a fraction of the SR71 and the Titanium used in the SR71 produced a much better structural mass fraction.

Overall one engineer summed the project by saying at an excellent talk a while back “the best projects are the ones where you learn the most, and even if this project outwardly looked pretty disappointing, we learnt one hell of a lot………..principally never again to make an airframe entirely from stainless steel! ……So as a project to underpin basic Concorde technology it was worth every penny”

As for the P1121 both a mock up and a flight article were built (or partially built). I’m pretty sure the bits of 1121 at Cosford are a flight article. When the Gyron was tested in a rig with air drawn through the proposed P1121 intake, it suffered badly from compressor surge. The compressor face air flow instability issue again. When an Oly was similarly tested the engine ran perfectly.

In my opinion the P1103, P1116, P1121 type aircraft had four figure production potential and as such its loss was the single most massive loss to the long term UK aerospace sector. That’s why Camm was so bitter about it and kept the model on his desk for so many years.

There’s something about it in Project Cancelled. I think Sidney Camm said it was about 85% complete but the board wouldn’t fund completion with no RAF requirement for the beast.

I have an article from 1959 that shows a picture of the prototype under construction at the time of cancellation. It certainly looks near completion but as I said I dont know enough about aircraft construction to comment.

There’s something about it in Project Cancelled. I think Sidney Camm said it was about 85% complete but the board wouldn’t fund completion with no RAF requirement for the beast.

A mock-up was built and photographs of this are sometimes claimed to be the prototype – some sources claim the prototype was around 85% complete when the plug was pulled but I can only assume this was as a private venture because the government had shown an utter lack of interest.

A pic of the mock-up here – http://prototypes.free.fr/p1127/p1127-3.htm

It was a private venture. I dont know enough about aircraft construction to comment on how complete it was but there are definately photos of it unde construction (not the mockup).

That is an excellent website for experimental prototypes etc, looks well researched. Makes me wish I could read French

It never flew but it got as far as the prototype being under construction, IIRC the fuselage section still exists somewhere.

A mock-up was built and photographs of this are sometimes claimed to be the prototype – some sources claim the prototype was around 85% complete when the plug was pulled but I can only assume this was as a private venture because the government had shown an utter lack of interest.

A pic of the mock-up here – http://prototypes.free.fr/p1127/p1127-3.htm