Just when you think you’ve seen most variations of the old engines out there, along comes something like this, a 3 cylinder, opposed piston, two stroke engine from Vincent. It was built with the goal of powering air dropped aluminum lifeboats for World War II Royal Air Force aircrews downed in the ocean. The war ended before the engine project was completed, but it was finished afterwards. This engine turned up in the list of items for the Bonhams Las Vegas motorcycle auction.
The description is quite interesting, especially how the different cylinders worked:
Like many other companies, Vincent shut down motorcycle production after 1939 and the factory was turned over to the war effort, mainly the making of munitions. But in 1942 the Royal Air Force, expecting a protracted campaign against the Japanese, was looking for a lightweight, highly efficient lifeboat engine that could run reliably for extended periods of time.
Company boss Phil Vincent already held patents on a suitable design, which he turned over to Phil Irving for final engineering. The result was a 500cc opposed-cylinder design with three bores each containing two pistons. The outer two cylinders produced power, while the middle cylinder with double-acting pistons fed the other two. Unfortunately, this unique engine program wasn’t completed before the end of hostilities, though in final form the motor seemed to meet all of its design goals. Producing 15bhp at 3,000 rpm, with 50 gallons of fuel on board, the Vincent two-stroke should have been good for up to 1,000 miles at a steady 5 knots
per hour, which certainly beats swimming or fighting off sharks. One batch of 50 engines was produced, and it’s believed that this example is one of 12 to survive.
We mentioned the Vincent Picador drone engine some time back, so it looks like the company had every part of the land-sea-air triad covered. Very neat!
A big Thanks to Kim who found this and who was also responsible for bringing the Vincent drone engine to our attention many years ago.
Nyanman says
It’s interesting they went with using the one piston set to force feed the remaining cylinders as opposed to using a small blower of some sort like a Commer TS3, especially for war duties more cylinders making power is more power, possibly essential in lifeboat usage.
Chris says
Minor correction: “five knots per hour” is actually a unit of acceleration, since the word “knot” means “nautical miles per hour”. The “per hour” in this case is redundant.
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Paul Crowe says
Fixed. When I copied the description from the auction listing I should have caught that. Thanks.
Paulinator says
I love your articles on the novel engines. Given the posted numbers, this engine would be plodding along while making about 3 hp. That is completely reasonable for 5 knots headway in a slippery boat. Is there any more detail available on the internal architecture?
Dave says
Vincent engine ; my research found that there was about 50 of these marine engines built. I was fortunate to be able to restore engine number ’62’ !?! for a local aircraft museum in Doncaster, U.K.
It was used post-war as it was adapted to fit under the Avro Shackleton. The engine is a strange 2-stroke configuration, as both cranks are oil fed with pre-heated oil, this was found to help start a cold engine. The inner 2 pistons compress the fuel and feed the outer pistons. The engine would have been liquid cooled and had a range of about 1000miles, the small 4-cylinder car engines that were tested had a range of about 500miles, The few engines that i have seen on the internet all have a double Vincent logo on their crank cases as they could be fitted to either side, this made casting easier.
ps Vincent tried making cars to be powered by their 1000cc v-twin, a water scooter, called the ‘miranda’ a moped, called the ‘firefly’ i seem to remember it only had a 23cc engine, ideal for women, but just underpowered ! they also made rotavators, possibly other farm & garden equipment & finally the Picador aero engine that was used in drone aircraft, Picador drones that were not shot down had a parachute system & another novel feature was that when the engine was stopped by the operator it stopped in the horizontal position to hopefully avoid damage on landing.
all the best, Dave
Paulinator says
Interesting. I make my way over to the UK from time to time. Always looking for another good aviation / engine museum (recently did Hendon).
Thanks and Cheers!!!
Michael Kamper, Grevenbroich, Germany, Jan. 2016 says
Allthough patented for Vincents, the double-piston engine was already known before to reduce fuel consumption. Where fuel consumption is of utmost importance, is aviation, where costs of an engine is secondary to safety and/or running costs/consumption.
That is why during WW2, Junkers built a 6cyl.-12piston diesel engine of this design as aircraft engine. It was also used to power locomotives and, after the war, as twin-cylinder, as a tractor
engine. The idea was at first, that diesel has a higher specific weight than aircraft fuel, so using the tank capacity of any aircraft more effectively. Moreover, the self-igniting diesel engines ran at a lower consumption than fuel burning engines. Which delivered a longer endurance of aircraft. The disadvantage of this idea was – which lead to the failure of this conceipt in aviation – that diesel became solid in freezing conditions, which are standard in flying altitude of bombers out of reach of flak- guns. A problem, which no longer exists, as diesel is frost-safe, by now.
Probably the most developed “double-piston engine” is to be seen at the railway museum in York, the “Omega-Engine” which propelled a Locomotive – if I remember correctly, at some 3000 hp. This engine uses 3 V-twin crankshafts, aranged at a triangle with 3 angles of 60 deg., the six pistons running on the 3 sides of the triangle against each other.
Each system of 3 cranks could be coupled to another one, so that you could add as much perfectly balanced systems to any desired power configuration.
A most impressive conceipt in competition to the radial engine, which had a less perfect balance.
Of course, the Omega engine was later than the Vincent “Uniflow-Engine” as was its name in the patent text, but the idea was older and lasted longer, than the Vincent patent.
Another interesting doublepistonengine was a motorcycle race engine, developed by the german ADLER factory, who made two strokes of 100, 200 and 250cc after WW2. This engine never left test conditions, but outperformed any contemporian 500cc two- or forstroke race engine. One example was found in the cellars of Braunschweig University in the 1980ies
and brought to operating condition and helped some young engineers to qualify for business life, delivering app. 80hp as a 500cc!
All the best Dave, with your Uniflow Engine at the Doncaster Aircraft Museum, I will surely come and have a look on it!
Michael Kamper, Germany
dave says
to Michael ; the diesel locomotive engine @ the National Railway Museum was used in the Deltic and was built by Napier, there was 22 Deltics built {excluding dp1 & dp2} they weighed 100ton and often travelled at 100mph all the Deltics had nameplates of famous racehorses or military regiments, several are still working, some under restoration some of these can be found at Barrow Hill ‘Roundhouse’, Stavely, Chesterfield, U.K.
regards dave