Cirrus aero engines

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steelpillow

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The ADC Cirrus was the first reliable and affordable aero engine and together with the de Havilland Moth, in the mid-1920s it created the golden age of private flying. It was also the first of the mass-produced small air-cooled four-cylinder inline light aircraft engines. And it has a curious, intriguing and only patchily-known history, its developed variants embracing a staggering quarter of a century in production and at least six manufacturers.

Aircraft Disposal Company (ADC)
Geoffrey de Havilland was mulling over what would become the Moth and realised that there was no suitable engine available: it had to be around 60-80 hp, but lighter and more reliable than the old workhorses. Meanwhile Major Frank Halford had revamped the old Renault V8 engine for the Aircraft Disposal Company, who had acquired hundreds if not thousands of them as WWI surplus. Its power doubled, it was being sold as the Airdisco. De Havilland had the bright idea of taking half the Renault and performing a similar miracle on it to create a four-cylinder inline. Halford took some persuading, and the result was the ADC Cirrus. The DH.60 Cirrus Moth launched it into the skies and into history. Developed variants the Cirrus II and III soon followed.

American Cirrus Engines Inc.
With the appearance of the III in 1929, American Cirrus Engines Inc. was set up to license-manufacture its own improved Cirrus III for the US market.

Cirrus Aero Engines Ltd
Presently de Havilland asked Halford to develop a more modern equivalent from scratch, which would become the Gipsy series. The engine designer had already severed his relationship with ADC, who were beginning to run out of the old Renaults and so Cirrus Aero Engines Ltd was formed, operating from the same address as ADC but without Halford, to start manufacturing the Cirrus range from scratch. They launched the improved Cirrus Hermes in 1929.

Cirrus-Hermes Engineering Company Limited
In 1931 the Cirrus-Hermes Engineering Company Limited was set up at Croydon, where they further developed the Cirrus-Hermes II and III. They next turned the Hermes II upside down as the II B, launching it early the next year and selling it alongside its upright sibling for a while. It put the cylinders below the propeller line, greatly improving the pilot's view, and the upright soon faded from their sales efforts. All future versions from the Hermes IV on would follow suit, as would Halford's de Havilland Gipsy range.

Cirrus Hermes Engineering Company Limited
In 1934 the company was bought up by Blackburn and moved to their base at Brough in Yorkshire. It remained a separate company under the same name but without the hyphen. Two new variants, apparently rationalising the range, were probably already under development and the Cirrus-Hermes Engineering Company Limited presently introduced the Cirrus Minor and Cirrus Major, in the same power ranges respectively as the Cirrus and Hermes types.

Blackburn Aircraft Cirrus Engines Division
With the new range in place, Blackburn swallowed the company into its own organization as its Cirrus Engine Division. The scaled-down Cirrus Midget was a development which was mentioned a few times in Flight but did not enter production. By the end of WWII Blackburn's range covered the Cirrus Minor II and Major II and III. Then in 1948 it introduced the ultimate fuel-injected version, the Cirrus Bombardier. By the late 1950s Cirrus manufacture seems to vanish from sight, eclipsed by the structurally more efficient and hence lighter flat-four arrangement.

Information is hard to find, especially on the post-Halford years. Much of this history comes from four sources; early history from Taylor's biography of Halford, Boxkite to Jet, and Sharp's history of de Havilland titled simply DH, with the fuller picture from Gunston's World Encyclopedia of Aero Engines and the many advertisements for Cirrus engines in the trade press, archived by Aviation Ancestry and findable at http://aviationancestry.co.uk/?searchQuery=cirrus&startYear=1925&endYear=1957
But that is just about it. Who took over the development after Halford left? I have heard that Philips and Powys of Miles aircraft fame were involved, but is there any truth in that? Who owned and ran all these various interim companies? What were the technical changes introduced with the post-Halford variants? Were 1929 contemporaries the American Cirrus III and Cirrus Hermes technically related? Did any others besides the Midget fall by the wayside? What obscure planes did they end up in - or not - after all? All snippets gratefully received!
 
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There was a guy named A.H.Caple that Flight says was designer at Cirrus-Hermes Engineering Co. He joined GAL's engine division in 1934, presumably when Blackburn bought the company.
 
Thank you. That has led me to another Flight commentary at https://archive.org/stream/Flight_I...nternational_Magazine_1935-02-28-pdf_djvu.txt

"Readers will remember that last year the Cirrus-Hermes Engineering Company left Croydon and was to a considerable extent re-formed, under the chairmanship of Mr. Robert Blackburn; large, modern and spacious works were erected at Brough, adjoining those of the Blackburn Aeroplane and Motor Company.​
​
"Some little time before the move to Brough, Mr. C. S. Napier, younger son of the well-known aero engine designer of that name, joined the company as technical director, and one of the first things he did was to produce, in collaboration with Mr. A. H. Caple, a very clean and eminently practical inertia engine starter. Some time before that Mr. Napier himself had under construction a small aero engine of low power, and it is therefore not surprising to find that the first engine from the new factory is one of 70-80 h.p., called the Cirrus “Minor.”"​

It goesd on to give a full technical description and, by the way the text column widths shrink, photos as well.
 
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Schneiderman said:
There was a guy named A.H.Caple that Flight says was designer at Cirrus-Hermes Engineering Co. He joined GAL's engine division in 1934, presumably when Blackburn bought the company.
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Oddly, he's listed as 'A.N. Caple' [sic] when author of Aeronautical Journal pieces like "Cirrus Mk III, by A. N. Caple. Journal of the R.A.S., London, May 1929, v. 33, no. 221, p. 386-'91". But, I believe, the Royal Aeronautical Society itself listed him among its members as Alfred Henry Caple.
 
Yes I noticed that. These errors creep in from time to time, which makes searching for people with more common surnames a little tricky. Luckily there aren't that many Caples around

EDIT. Just checked the patent database and that confirms that he was indeed Alfred Henry Caple
 
steelpillow said:
.....How I wish they'd get their proper archive back on line!
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Couldn't agree more, I've wanted to consult it so many times in the last few months and now that I cannot get to a library to consult bound volumes either its getting really annoying
 
I got sidetracked into the roots of all Halford's early piston aero engines and those derived from them. They are legion, it is quite astonishing the influence this man had, and I haven't even looked at his fancier stuff. Besides a few outliers they fall into two main families of which the Cirrus lineage forms the heart of the main one. I drew up a chart of them all, see attached.
 

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SP: Phillips&Powis. RR bought in and provided a Joint MD, 5/36-3/41 (to promote Miles M.9 Kestrel Trainer, to be Master Mks.I/IA).

Blackburn operated Elementary Flying Schools and tried to compete v. DH Tiger Moth with metal B-2, offered with DH Gipsy (Duh!) and Hermes, so they had bought Cirrus-Hermes Eng'g Co. in 1934.

Control of Blackburn was taken 4/36 by the Cowdray family (numerous Aero interests, inc. General A/c who in 1935 licenced Hispano-Suiza 12Y). Cirrus II/III were not relevant, so were licenced to (Phillips&Powis) F.G.Miles, who also took a licence for Menasco C4. Do we suppose FGM, too, was bothered by power dependency on an airframe competitor? These licences lapsed about when RR sold to the Miles family, 3/41.

P.Amos,Miles/II,P.26 has (P&P) 5/42 running an own-design 1,740hp flat 6 aimed at X-types.
 
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Um. Phillips & Powis are not mentioned in Gunstons' World Encyclopaedia of Aero Engines. There was a Lord Cowdray involved in various aeronautical matters, but I can find no involvement with Blackburn. According to the BAe Systems Heritage website the 1936 venture was with one Maurice Denny, a Dumbarton Shipbuilder. Nor does an own-design flat six seem relevant here, even if I could figure your cryptic citation. What are your sources for all these incongruous claims?
 
Cowdray was Br.Pacific Trust, involved in the 30s with Br.Airways, Blackburn, General et al. Recapitalised Blackburn entered a collaboration with Denny/Dumbarton which saw Sunderlands built during the war and continued post-war. Peter Amos's AirBritain Miles volumes has the flat 6 in Volume 2 as noted.
 
alertken said:
Cowdray was Br.Pacific Trust, involved in the 30s with Br.Airways, Blackburn, General et al. Recapitalised Blackburn entered a collaboration with Denny/Dumbarton which saw Sunderlands built during the war and continued post-war. Peter Amos's AirBritain Miles volumes has the flat 6 in Volume 2 as noted.
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Oh yes indeed. The machinations and wider interests of the various investment funds, trusts and major shareholder groups is overlooked far too often in the history of the industry, especially in the '30s.
 
Thank you. Still no references to the relevant claims (any P&P flat-six is not relevant to Cirrus), pardon me if I reserve judgement on their validity. By the way, Viscount Cowdray was a title, there was no such thing in this context as the "Cowdray family".
 
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The Cowdray title has been held by the Pearson family since 1910.

In that year John Churchill Pearson, became Baron and then in 1917 becoming a Viscount. He set up Whitehall Securities in 1907 and served as President of the Air Board in early 1917, switched the family business S. Pearson & Son Ltd. away from construction and into publishing during the 1920s. Died 1927.
The title of Viscount passed to Weetman Harold Miller Pearson, he was involved in the foundation of Whitehall Securities alongside his father. Died in 1933.
Then Lt Col John Churchill Pearson took the title. He lost an arm during the early part of WW2 and served as Parliamentary Private Secretary to the Under-Secretary of State for Air, Harold Balfour during 1941-42, became Chairman of the family business S. Pearson & Son Ltd. in 1954.

It was the 1st Viscount's second eldest son (his third son being killed in 1914), Bernard Clive Pearson, who took on the chairmanship of Whitehall Securities in 1935, although notably its acquisition of airline shareholdings had already begun by the time of his tenure.

I don't know much about the British Pacific Trust, it seems to have been founded by Canadian Alfred Taylor out of his British Pacific Securities founded in 1928 for investments in British Columbia and British Pacific Properties Ltd. which had the backing of Lord Southborough, the Guinness interests and a lot of other British investors. The Depression Years seem to have been boom time for Taylor and British Pacific Securities. Taylor also served as a technical advisor for the Ministry of Aircraft Production in both Canada and Washington. Canadian WW1 pilot/ radio entrepreneur millionaire William Stephenson was also involved in the Trust, I have seen online references to the Trust's shadowy 'British Industrial Secret Service' of paid informers etc. which saw Stephenson getting involved with MI6 in 1939.
Airlines of Australia was another BPT-funded enterprise, and the motorcycle company Douglas was also recapitalised, it was the Douglas factory where General Aircraft would exercise their Hispano-Suiza licenced production.
 
In my #11 I muddled my vultures.

Cowdray's Whitehall Securities (owning Lazard Bros, the Finance House):
1933: control Saro,
April,1936 float and buy equity in Blackburn (who had bought Cirrus-Hermes, 1/3/34),
(soon: ) decide Cirrus II/III are non-core and sell (?licence ?more) to P&P (RR equity+Jt.MD, 4/36): {1942:}"Geo.Miles had been interested in aero-engines for many years" Amos/II,P.25.

Br.Pacific Trust (Guinness money) 4/10/34 float and buy equity in General A/c,
20/6/35 float GAL subsidiary Aero-Engines Ltd, licensee for Hispano-Suiza range.

(Here comes muddle: 1938 BPT sells (GAL lease on) Hanworth Air Park to...(Blackburn, funded by) Whitehall Securities).

So: sp's Q was: why were P&P/Miles (so RR) involved in Cirrii? My surmise is that in 1934 Blackburn was uncomfortable with dependence on DH to power their trainer, while competing with it. Robert B found the capital to buy Cirrus and invest in new facilities in Brough. By 1936 new investors' interest in Blackburn had nothing to do with Elementary trainers and their engines, but was all to do with the (then-equivalent of the dot.com bubble: ) Rearmament turret fighters, Coastal patrol, Sharks.

If quite a modest sum was sought by (Whitehall) to narrow their small-piston distraction, G.MIles could have persuaded RR of the benefit of power options other than DH.

Nothing came of any of this (H-S licence; lots of Cirrii; Nuffield trying to resurrect Wolseley in aero-engines; Fairey trying to get in) because Ministers saw the established Engine Ring as already overloaded, design+production, so discouraged (airframe and) engine new entrants. Scarce "draughtsmen".
 
The Nuffield story is told briefly by Arthur Ord-Hume in his piece on the Essex Aero Sprite. He ascribes its demise to Miles and Auster's enforced lock-in to Blackburn and de Havilland matching its Gipsy production to its own needs. I find it hard to explain why Philips and Powys would have bought engine designs off Blackburn, only to continue exclusively buying engines of their manufacture. Something is missing from the story.

Looking at Blackburn's B-2 trainer of 1932, its styling is such a rip-off of the DH Tiger Moth that it seems obvious that Blackburn acquired Cirrus Hermes so that he could oust the DH Gipsy from his B-2. Which, in 1937, he duly did. Unfortnately the Tiger Moth was immovable and he only sold a handful. Sure, with the Cirrus Minor and Major in production it would do no harm to make a little extra pocket money by selling off the obsolete upright variants. Those would more likely be the Hermes II and III rather than the long-dead Cirrus II and III, but all were upright.

So even if P&P did plan to develop their own design, why on earth would they want to base it on obsolete and awkward upright engines, when the B-2 and every similar-sized monoplane they would design for some years to come used the more modern and practical inverted types? That leaves a second inexplicable gap in the story.

I fear the cryptic sources offered above are beyond my willpower to decode, and there appear to be no others, so forgive me if I continue to doubt the veracity of the sale; a vague interest, somebody else's flat-four and an unconnected aside in some business tittle-tattle do not a Cirrus sale make. Nor can I see anybody putting Cirrus Majors in a turret fighter. Even if I could decode the reference and obtain a copy, I am not sure that I would believe it without independent corroborating evidence.
 
The proposed (a prototype was tested) Miles 6-cyl horizontally-opposed engine was designed for 1,740hp - somewhat more powerful than the kind of light aircraft engines this thread is talking about.
It was intended for the X-series of blended wing designs, its flat shape being ideal for buried installations compared with bulkier V-12s.
Apparently, according to Peter Amos' book, the prototype was run to 70% power on a dynameter, but I am sceptical that you could get 1,740hp from a flat-6 with 1942 technology.
 
Hood said:
The proposed (a prototype was tested) Miles 6-cyl horizontally-opposed engine was designed for 1,740hp - somewhat more powerful than the kind of light aircraft engines this thread is talking about.
It was intended for the X-series of blended wing designs, its flat shape being ideal for buried installations compared with bulkier V-12s.
Apparently, according to Peter Amos' book, the prototype was run to 70% power on a dynameter, but I am sceptical that you could get 1,740hp from a flat-6 with 1942 technology.
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That's comparable to a 12-cylinder Griffon! Somebody is not telling it straight (or, to perpetuate the pun, that it flatly unbelievable). ;)
 
Indeed, even the tenth prototype RR Crecy only managed 1,798hp without a supercharger!
I suspect there is far more behind the tale but only scant information is given in the book. I forgot to mention the engine was air-cooled to boot! Either the power rating was erroneously recollected or they were hoping to stick a big supercharger on it.

The design team consisted of four draughtsmen, one being Michael S Wooding who was responsible for the camshaft, poppets and valve gear; another was Sid Porter (former Autocar illustrator) and the team was led by Arthur Ham who was an expert on the design of ticket machines.
I would hate to harshly judge, but this hardly sounds like a cutting-edge team steeped in engine technology knowledge to pull off such an engine.
Either the power rating was erroneously recollected or they were hoping to stick a big supercharger on it.

I think in anything related to Miles it must be borne in mind that the Miles brothers were extraordinarily interested in everything technical, from assembly lines, variable pitch propellers, novel aerodynamics, glassfibre construction, Brio pens, photocopiers, simulators, engines - the list is endless. They were mechanical wonderers and tinkerers. They always wanted to investigate the new and play around with it and see what could be done - very much like the pioneer aviators were. It was this drive that made them build unsanctioned prototypes in the M.35 and M.39B. But sadly the 1940s and beyond were no time for tinkerers who had good ideas, you needed money and resources and above all commitment to see it through to the end. I don't think its any coincidence that despite the wide array of designs that they drew up, that Miles always remained essentially a producer of trainers and light aircraft - the MAP just never had the confidence in them to really take the next step to become a serious large manufacturing concern (in fact at the end the Biros and photocopiers were making them more money than aircraft!).

The reality is probably that Miles secured the Cirrus rights as it seemed a good idea at the time for whatever plans they had for the engine but later the idea faded away.
 
It's difficult to see why they would want the rights to the Cirrus when they already had a licence deal for the broadly comparable Menasco engines, unless there were issues around constructing engines of non-British origin. As did down Alvis' aspirations.

One of the Miles brothers weaknesses was that the brochures and projects they submitted were short on detail, the AM commented on this and an independent consultant's report in 1947, as the company was ailing, said "For each of the types considered an illustrated brochure has been issued. These brochures have been reasonably attractive in form......But they have not contained the technical information and details which a normal operator would expect to find and which he must have before deciding to adopt the type.."
 
Schneiderman said:
It's difficult to see why they would want the rights to the Cirrus when they already had a licence deal for the broadly comparable Menasco engines
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The Menasco Pirate series, of which the aforementioned C4 is an example, were licensed derivatives of the Cirrus III, courtesy of Menasco's acquisition of the American Cirrus Engines (ACE) assets. The design had by now been inverted by ACE (as the American Cirrus Hi-Drive) independently from both Napier at Cirrus-Hermes and Halford at de Havilland.

Indeed it is difficult to see the attraction of collecting Menasco's ancestral fossils. Possibly there could have been some technology license or similar wrapped up in the Cirrus/Hermes deal, which was of more value than the overall engine design.
 
Hood said:
The proposed (a prototype was tested) Miles 6-cyl horizontally-opposed engine was designed for 1,740hp - somewhat more powerful than the kind of light aircraft engines this thread is talking about.
It was intended for the X-series of blended wing designs, its flat shape being ideal for buried installations compared with bulkier V-12s.
Apparently, according to Peter Amos' book, the prototype was run to 70% power on a dynameter, but I am sceptical that you could get 1,740hp from a flat-6 with 1942 technology.
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There were definite, albeit tentative, plans to produce a horizontally opposed engine of ~1740hp for the X aircraft, the original blueprints in Amos' book show that in the specification box. As one of the original design team say a 6-cylinder engines was bench-tested, that has to be taken as true too. However I very much doubt that the test engine and the one destined for the aircraft were one and the same, as I share your scepticism.
 
steelpillow said:
The Menasco Pirate series, of which the aforementioned C4 is an example, were licensed derivatives of the Cirrus III, courtesy of Menasco's acquisition of the American Cirrus Engines (ACE) assets. The design had by now been inverted by ACE (as the American Cirrus Hi-Drive) independently from both Napier at Cirrus-Hermes and Halford at de Havilland.

Indeed it is difficult to see the attraction of collecting Menasco's ancestral fossils. Possibly there could have been some technology license or similar wrapped up in the Cirrus/Hermes deal, which was of more value than the overall engine design.
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Not sure which Menasco engines were in the licence deal but it certainly included the B.6.S Buccaneer and C.6.S Super Buccaneer
 
Just been trawling the Espacenet patents site. Can't find anything spectacular, but these help:

Alfred Henry Caple took out several patents on inertia starters, jointly with the Cirrus Hermes Engineering Company, applying for the first in 1932. GB377810A and GB417128A give London addresses, GB425264A was applied for in 1935 and gives Brough, the home of Blackburne's.

Carill Stanley Napier was a son of Montague Stanley Napier, at least according to WikiTree. Together with Blackburn Aircraft Ltd. he applied for GB480576A, also on inertia starters, in 1937.
 

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