Pilot

July 2002

 

"First flight behind the Wilksch diesel engine"

"Cooling trials of the Wilksch Airmotive (WAM) diesel (in a Europa) were halted by poor weather, so journalists were given the chance to fly some quick circuits. As it happened, I was the only one who could make it.

When I arrived, the WAM powered Europa was taxiing to make a short flight, so I had a chance to listen to the engine from the outside. I was expecting something unusual, but it sounded to me like a well-silenced Lycoming. A Vedeneyev, Gipsy or VW engine has a unique sound, but I doubt whether anyone will be able to detect a Wilksch diesel in this way.

There was no visible exhaust emission.The top cowling was removed so that I could have a look.

The WAM diesel has three inverted, in-line cylinders.Air is sucked in from the port side, speeded on its way by a turbocharger driven by exhaust gases.This heats it, so it is passed through a cooler at the front of the engine. Also at the front is the water radiator - the diesel is liquid-cooled.

The air is then passed to a blower on the starboard side - this one has engine driven rotors and doesn’t rely on exhaust gases - and finally released to the cylinders. Here it is joined by fuel, squirted neat through injectors using a mechanical system chosen for its compatibility with JET-Al fuels.

The WAM engine does not sound at all like a petrol two-stroke.Mark laughed when I said this, a diesel two-stroke being quite different. The WAM ‘CITEC’ concept is constructed just like a conventional four-stroke engine, with a wet sump and valves operated by an overhead camshaft.

There is a simple box for the exhaust silencer.

As it’s a diesel, there are no magnetos.There is an electric starter and alternator.

Having no need of air ducting round the cylinders, and no magnetos, I thought the installation looked cleaner and simpler than for an air-cooled Lycoming of the same power.Simple installation could be one of this engine's selling points.

The prototype has produced over 130 hp, but has been de-rated to 100 hp for these flight trials. Production models should be allowed to develop the full, designed 120 hp. According to Mark, the price will be the same as the equivalent Rotax, and weight comparative with Lycomings and Continentals in the 90-120 hp range.

The engine was fitted with a ground-adjustable three-blade MT propeller (direct drive, not geared). A hydraulic, variable-pitch option will be available for the production engine.

Cockpit controls couldn’t be simpler, and this is one of the WAM team's most significant achievements. WAM's engine is also claimed to have the best power-to-weight for a diesel, allowing installation in aircraft as small as the Europa with growth potential for four-sear aircraft.

All the pilot has to contend with are:- a start switch that is turned anti-clockwise for five seconds' pre-heat, then clockwise to engage the starter motor;- a power lever;- ­a pull-to-stop lever;- a torque gauge that does the same job as an rpm gauge.

That's all: no carb bent, no mag switches, and no mixture control.There are the usual temperature and pressure gauges, but these will be replaced with a single small LCD screen.

I was able to make two circuits.The engine started after three seconds' cranking.It responded immediately when I opened the throttle (actually, the 'torque control'). Not much noise through my headset in cruise or at take-off.Throttling back to land, engine tick-over was smooth, but set rather fast. (I was told that this was just a matter of adjustment, and not a characteristic of the engine.)

The engine did everything I asked of it, and did it well.

The main point of the Wilksch diesel is its lower running costs through cheaper fuel and reduced fuel consumption.If it can match ‘conventional’ engines for simplicity, cost and power to weight, then by definition, it has to be a winner.

Wilksch Airmotive has taken the first order for its four-cylinder 160 hp rated engine. Like the WAM-120 the -160 will be a turbocharged in-line inverted engine with integral oil and cooling system. Mountings will be identical to the WAM-120 using WAM's patented 'ParaFocal' system. A WAM-160 will be on display at the PFA Rally at Cranfield.

The WAM-160 price has set at £15,000 (less 10% discount for the first ten customers).

Wilksch Airmotive are planning to have the first WAM-160 engines running in Spring 2003 with first customer deliveries scheduled for Autumn 2003.

Nick Bloom"

 

"Right: Compact design of the Wilksch Air Motive (WAM) Turbo-Diesel engine and intercooler (front) will endear it to builders."