Delta Helicopter

Among the surprises at Avalon was Delta Helicopters’ all-new two-seater, powered by a 200 horsepower Delta Hawk two-stroke Diesel power plant, which is about as simple as an engine can get.

Its designer is well-known CAR 35 engineer Bill Whitney, who has already designed several successful Australian aircraft, says Graeme Smith, Managing Director of the private company.

Mr Smith represented Rotorway kit helicopters for about ten years, and first tried to respond to customer calls for more power by fitting the Diesel to existing Rotorway airframes. The engine startled him by lifting the tethered Rotorway helicopter and its trailer during trials, but he found the retrofit process too complex and beyond most owners’ skills and equipment, so he decided to design his own airframe.

The outcome has been a handsome and professional-looking light helicopter which is now expected to make its first flight by March 27, says Mr Smith, who plans initially to promote the aircraft as a kit build:

“Even though Bill designed it to comply with the FAR 27 regulations, we decided to offer it first as a kit for the amateur built experimental market, so owners can maintain it themselves, and the cost savings to them are considerable. We’ll be able to incorporate any improvements customers suggest, and with lots of people looking at it we can make any changes with a view of perfecting it. By the time we’ve been through that process over two years, we’d expect to have an aircraft that everybody loves and we can do any changes that we feel are warranted, and we’ll have had a lot of people looking at it with a view of perfecting it. So when we go to certification, after which you can’t change it, we’ll be almost there.

“We’re targeting the farmer who wants a simple-to-maintain helicopter because there’s already diesel available at any farm. The diesel also offers simplicity with no magnetos, spark plugs or complex electronic fuel injection systems, and fewer moving parts.

“We designed everything on this helicopter with the exception of the engine, and built everything else but the rotor blades which were built by a specialist company in France to our specifications. We buy standard aviation hardware, but every other part – the rotor head, the blades, the drive and control systems, gearbox, the body and undercarriage, are designed and built by us.”

The Delta Hawk water-cooled engine was designed from the ground up to be an aircraft engine that can be retrofitted into any aircraft that currently can use a Lycoming O-320 or O-360, or a Continental between 160 and 200 hp. The engine is available in 160, 180 or 200 HP variants, and the Delta helicopter uses the 200 HP model. The various engines have the same block, pistons and cylinders, and only vary in the sizes of their intercoolers and turbochargers.

“In the 200 HP engine, both the torque and horsepower curves are still climbing when the engine reaches its 2700 RPM limit, so we’re not anywhere near the peak capability of that engine.” says Mr Smith. “Because it’s water cooled we have a cooling system that is unique. The cooling radiators for water, fuel, oil, hydraulics and intercooler are all underneath the cowl, and are fed by two scoops on the top of the helicopter which also feed the engine, so one single hydraulically driven fan draws air through all of them and dumps it out the back. In forward flight we’ll get ram assistance, while in hover all the cooling is done by the fan,, remembering that a diesel engine doesn’t get anywhere near as hot as a petrol engine, so we can do all that quite successfully.

“The other aspect of the design is that all the air that’s used for cooling the engine comes from the top of the airframe, so we’re drawing in the cleanest possible air we can get.”

The cabin appears spacious compared with existing commercially built two-seaters, and the aircraft also has one dedicated cargo pod accessible from both sides built-in to the fuselage.

Rotor RPM is 436 and rotor head parts are expected to retire at about 5,000 hours. The rotor blades, designed by a design engineer who had been working for Eurocopter for the last 40 years, incorporate the latest thinking in aerodynamics, says Smith: “We haven’t calculated direct operating costs yet but we burn 35 Lit/hr at max power so fuel will be around $45, and Smith has guesstimated the replacement of on-condition parts as 5,000 hours for the gearbox, and bearings at 2,500 hours. The blades are on condition, so probably about $100 an hour for all maintenance. Engine TBO is 2500 hours but it’s only $4500 to rebuild it:

“To assist the pilot doing preflights, inspection covers along the boom allow them to see the tail rotor drive bearing supports, all of which have “teletemps” that indicate if a bearing is starting to overheat which may cause it to fail, and you can see all the bolts to check for cracked parts without a using screwdriver. Fuel tank sight gauges also allow the fuel quantity checking without even getting into the helicopter. Our carbon fibre rotor blades are on condition so if you don’t smash them into a tree they’ll be good for the life of the aircraft.”

Related Articles

• No Related Post