True Rotorheads - A visit to Diamond MarK Wrathall - 14/MAR/2004A Paul Lamar organised a trip to Wiener Neustadt, to visit Diamond Aircrafts new rotory engine facilities. Luckily I got to tag along. (No Link) Paul Lamar with Martin Rühe, the manager of diamond engines. Martin is a true Rotorhead. He proudly showed us his Hercules W2000 which he has been riding for years. Powered by a Sachs KM 914, the internal parts are interchangeably with the Diamond Engine components. A chemist by profession, he joined Mid-West Aero about seven years ago, and made the move to Wiener Neustadt when Diamond decided to take it over. Richard Negus has been a rotorhead about as long as I have been alive. He joined BSA in 1964, and after the merger of BSA, Triumph and Norton, got involved in the Rotory powered Norton racing team in 1972. This project peaked with over 100 people involved in 1991-92, by which ime Richard was burnt out. He left the company, but after only a few months was drawn back to the rotory to work for Mid-West Aero. He has been involved ever since, having bought the spare parts assets of Norton a few years ago, and consulting for Diamond. Richard gave us a fascinating overview of the family tree of the Sacks KM 914 derivatives. A completed R2 (The internal reference to the 100HP two rotor), ready to go out the door to some lucky home builder. Mid West production was slow but pretty consistant. The main customer was Schliecher, who used the R1 in high performance self launching gliders. This R2 will go to a UAV helicoptor. Note the drive belt pulley. The main feature here is the blower used to cool the rotors, bearings and side housings. Consuming about 3-5HP, it is the price you pay to avoid a recirculating oil system. Best economy peaks at 260g/kW/h, with average fuel consumption around 300g/kW/h. An off the shelf oil injection pump is used to provide metered oil flow. Oil to fuel ratio works out at about 1:110. Although the engine has a total loss oil system, actual consumption is less than the falls within the normal range for a Rotax 912. About half the oil is sprayed in a port in the end housing, where is mixes with the cooling air to lubricate and cool the main rotor and e-shaft bearings. The rest of the oil is injected into the throttle bodies for apex seal lubrication. As the rotor bearing temperature is the critical limiting parameter on TBO, the engine has been certified for use only a select few oils, which interestingly enough are not two-stroke oils. A balanced assembly. Rotor, E-shaft, Flywheel, Counterweight and bearing become a matched balanced assembly. The Balancing machine used. This engine is still set up for low volume production. Here is a rotor which has been quarantined due to unattractive balancing by a sub-vendor. A batch of raw rotor housing castings. These housings are water cooled, with the waterjacket enclosed (The end housings are air cooled). There is no need for O-rings between housings. These were previosuly ground on a cam driven rotor grinding machine at Norton (the one built by Sachs in the early sixties). With the final termination of the Norton factory building leases last year, this machine was sold for 45GBP, to a fellow who didn't even try to haul it away once he saw how massive it was. They have just had a trial batch CNC ground, which have come out the most accurate rotor housings ever. This housing is out of an engine which has run for ~400 hours in a Diamond Katana, and was removed for engineering analysis. The highest time engine that they know of is an R2 in Italy which was last reported as having 780 hours. The vast majority of the R1's used in the self lauching Schleichers will never accumulate many hours due to the nature of that operation. One of the Schleicher motor gliders has flown from Europe to South America three times!!! (Sore butt!) As you can see it has a very light chatter pattern in the Nikasil, but it is bearly perceptable to touch. There were rumours of issues with the Mid-West Aero engines Nikasil coatings. Martin informed us they had used two different vendors in England, one of which was dropped due to an unsatisfactory batch. Diamond have designed a new engine with a displacment of just under 400cc/rotor (up from 294cc for all Fichtel and Sachs KM914 derivatives). Here you can see the difference between the rotors. Martin and Richard were very gracious hosts, who generously gave us three hours of there saturday. They were very open about the engine and obviously proud of it. Diamond is currently not producing it's Rotax 912 powered two seaters for the european market (the Katanas for the North america are made in Canada and have Continental IO-240's), so we have to hope that the next batch of Katana's and Dimona motorgliders have Rotary engines.