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V8 Power Brings Economy and Speed

A high nose and substantial landing gear fairings give Altitude Group’s V8 powered P85 a classic race plane appearance.

By Randy Dufault

July 23, 2015 - Power systems developed for vehicle propulsion outside of aviation have one thing going for them that the aircraft industry, amateur-built or otherwise, cannot typically offer: sheer volume.

“I can’t even imagine how much money GM has invested in developing these engines,” Jeff Ackland of Altitude Group LLC said about the V8 LS engine he is using the company’s new P85 kit design.

The P85 is a derivative of Altitude Group’s Radial Rocket. That aircraft is designed to use the Vedeneyev M14PF Russian nine-cylinder radial engine.

“If you do an all-bells-and-whistles 400-hp M14P, get a constant speed prop, and buy your engine accessories—all that jazz, realistically you are going to spend about $75,000 for the firewall forward,” Ackland said. “Which really, for 400-hp these days, is, believe it or not, a good deal for the total power plant package.

“This V8 package is $20,000 to $24,000 firewall forward. Actually horsepower for horsepower, with the same gear configuration, [the airplane will be] 25 mph faster than with the M14.

“And, of course, we can burn 91 octane mogas. I think there are some things here that will draw people to that installation.”

The fixed-gear, taildragger version of the P85 Ackland has here at EAA AirVenture Oshkosh 2015 is, like a similarly configured Radial Rocket, reminiscent of the Granville Brothers Gee Bee race planes. The nose stands high and the generous landing gear fairings evoke a very classic appearance.

For the time being a rough coat of primer covers the craft’s composite airframe. Ackland said that the unfinished appearance is due to the project’s development stage. He expects some more small airframe changes as refinement of the cooling system is completed.

A marine version of the GM LS3 V8 powers the P85. Marine duty cycles, where high continuous power levels are required for extended lengths of time, are similar to what is demanded in an aircraft application.

Much like he did with the engine, Ackland turned to another vehicle type for the reduction drive system necessary when connecting an automotive engine to an aircraft propeller.

“We have a redrive that is built by a company called Ballistic Drives,” Ackland said. “It comes out of the airboat world. They are based in Kansas and it is a beautiful, well-engineered, very stout shaft, very stout gear redrive. It has been engineering analyzed for use in airplanes and it has got plenty of margin. The airboat guys beat on them with 1,500 hp for racing.”

A fixed pitch prop rounds out the economical power package. Ackland expects some builders will opt for a constant speed prop, but he wants to demonstrate that fixed pitch can still deliver performance at a dramatically lower cost.

Other landing gear configurations are planned for the design as well.

Overall Ackland believes the P85 is meeting the goals the company set out to achieve.

“The initial philosophy for this airplane is to show how much performance you can get out of a very simple, very cost effective, propulsion system and airplane,” he said. “I think with fixed gear and a much less exotic engine, this airplane will be capable of 300 mph straight and level.

“That works for me.”
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