UK Aircraft Diesel Engines, II
The last couple of years development in aircraft engines has been more or less concentrating on diesel engines. We have seen one off installations to fully developed engine production lines. A number of companies are active on this market primarily due to major concern of long term availability and the relative high price of AVgas (Europe).
Diesel engines are able to use JET fuel (avtur). This fuel is worldwide available and can also be made of renewable sources (biomass) which will contribute to a cleaner environment.
In the United Kingdom are a number of aircraft diesel engine manufacturers active: Wilksch Airmotive, Diesel Air Limited and Powerplant Developments. We will shine a light on each to see what they have to offer to the experimental aircraft market.
Wilksch Airmotive Ltd.
Wilksch Airmotive Diesel Engine
Wilksch has been developing their range of engines since the mid 90's when they flew a proof of concept engine in a J-3 Cub. This was a two cylinder model and capable of 80 bhp but was limited to 60 bhp. Late 1999 they had their three cylinder model flying in a Europa aircraft, this is the 120 bhp engine and is also used in a LongEZE, Thorp T-211, Murphy Rebel Elite and Vans RV-9. They also have a three cylinder 100 bhp model flying in a Pietenpol Aircamper.
Development is still going strong and a four cylinder 160 bhp is under test. We expect that more power is possible in these engines and that the current 120/160 bhp limitation could be raised to at least 130/170 bhp with proper engine cooling design.
Wide Bore
At this moment (early 2009) Wilksch have a 'wide bore' WAM-120 which develops some 140 bhp, ideal for RV-9 and Murphy Elite weight class aircraft. Source Wilksch.net.
WAM engines have a inlet port and exhaust valves and this is perfect for exact engine timing and tuning. We also have a diagram showing the Wilksch Diesel engine operating principle
Wilksch Diesel engine operating principle.
For engine startup a supercharger is fitted supported by a large truck size turbo for normal engine operations. Provisions for a hydraulic propellor control is available. The alternator is installed on the back of the engine and driven by gears. The engine features an intercooler and glycol/water cooling system.
Diesel Air Ltd.
Once working together with Wilksch Airmotive, they decided to pursue a different engine design. The DAIR-100 is of the opposed piston like the JUMO design and has two cylinders with two pistons each acting toward each other. There are thus two crankshafts driving the propeller through a gearset.
From the site: "The twin cylinder opposed piston engine has two pistons in each cylinder with the combustion chamber formed between the crowns of the pistons. It eliminates the need for a cylinder head, camshaft and associated valves and has in effect two half length crankshafts linked by a gear train driving a centrally mounted propeller. The cylinders are ported at each end with one ring of ports opened by the air piston supplying the fresh air charge, and the other opened by the exhaust piston and connected to the exhaust system."
The engine has flown in a Luscombe aircraft, power boats and on an Airship with good results. Power developed is 100 bhp without turbo charger, with a turbo power is increased by 20%. They sell the engine in licence through other manufacturers. Dieseltech sells this engine as the Powerlite-100.
Do keep an eye on these manufacturers, the future of aircraft diesel engines is really promising!
