View Full Version : Mystery light aero engines

20th Jan 2004, 00:37
Richard Riding, in his excellent book "Elstree Aerodrome", refers to a company called Monaco Engines of Kings Langley who had hoped to develop a range of light aircraft aero engines in the 1940s. The picture shows a very "Lycoming" type of engine.
I also would like to know what happened to the light twin cylinder engine that was being developed for the Lotus Cars chief Colin Chapman's microlight.
Finally AC Cars had a flat four and flat six under development in the late 1940's though this was for automobile use I assume.
Any info on these 3 engines would be gratefully received via this site. It does seem that we missed the boat at this time but hindsight is always 20/20.

20th Jan 2004, 04:10
Monaco was developing two flat-fours, a 3 3-litre and a 3.6-litre, producing, respectively, 75 hp and 100 hp at 2,200 rpm. A prototype bench ran, and was due to have been flight-tested in an Auster Autocrat, but I don't think this ever took place. The Monaco was to have been supplied as a firewall-forward ‘power egg’, complete with cowling. At the same time the Engine Branch of the Nuffield Organisation was developing a 3.82-litre, 100 hp flat-four that was to power the two-seat, magnesium-skinned Essex Aero Sprite. And Roy Fedden Ltd was developing direct-drive and geared flat-sixes of 160 hp and 185 hp respectively. They were low-profile engines (just 14 in high) and could have been ‘buried’ in wings of twins driving propellers via extension shafts. Erco, manufacturer of the Ercoupe, had a development contract with Fedden, but the loss of a Ministry of Supply contract to develop the Cotswold turbine engine, and Erco’s withdrawal from the flat-six project, led to the Cheltenham’s based company’s closure in the summer of 1947.

20th Jan 2004, 17:50
Thanks for that Aerohack. The Monaco "power egg" would have gone down well with today's PFA homebuilders particularly with a company designed cowling. Some of the designs at the PFA Rally do seem a little lacking on the aerodynamic front but what would I know, I'm a civil engineer not an aero engineer.
If all the designs had gone ahead there would have been a really good range of UK-built engines from 75 to 200 hp. Opportunity lost I guess.
Your reference to the Essex Aero Sprite was a new one on me. Do you have any further info?

20th Jan 2004, 18:56
The Essex Aero Sprite was a two-seat, low-wing design with fixed tricycle undercarriage and a V-tail — bit like a small Navion with a Bonanza’s tail. I think the major parts of the whole airframe were magnesium, not just the skinning. A retractable gear version was also planned. The prototype was built at Broxbourne and was reportedly well advanced, but it never flew — one of a number of now all-but-forgotten post-war British light aircraft projects that came to naught.

21st Jan 2004, 00:43
Some years ago, in Southampton's Hall of Aviation, I saw an aircooled flat-6 on display with a Rolls-Royce badge/logo on it (maybe it's still there). I remember it because I thought at the time how neatly it would appear to fit in the back of a 911, and what a unique combination it would be.

I have not come across any mention of it in print either before or since - was it a literal case of badge-engineering, or maybe somehow connected with those already mentioned?

21st Jan 2004, 01:14
R-R Crewe licence-built Continental Motors' flat-fours and -sixes from 1961 until 1981 or thereabouts. I suspect it was one of those. Lots of Reims-built Cessnas and other types about correctly wearing 'RR' plaques on their cowlings. Never seen a 911 with one though...

21st Jan 2004, 19:02
I'm intrigued by the reference to the Essex Aero Sprite. I'd never seen a mention of it and Google doesn't come up with anything. Are there any pictures to be had? I wonder why the 40's engineers went for magnesium. There was another a/c called the Planet Satellite that was mainly magnesium, I believe, and that didn't progress either. Essex also seems to be an unlucky county for light aircraft designs as I rememeber seeing a thing called the Tawney Owl at Stapleford years ago. It was a low-wing pusher with twin booms and it apparently failed to get airborne on it's maiden flight. Heard a rumour that it was being considered for a re-engine and a re-build. Any truth in that?