|Aeronautical engineer Joe Hutterer received a patent for his hybrid powered aircraft concept. Propulsion for the craft comes from a turboprop pusher engine and retractable jet in the nose. (photo by Randy Dufault)
|Hybrid airplane with jet extended (photo by Ric Wolford)
By Randy Dufault
July 29, 2013 - Over the course of a long career with the likes of Mooney and Beechcraft, aeronautical engineer Joe Hutterer became convinced there was a better way to build a business aircraft.
His concept is a hybrid propulsion system, though not the typical hybrid-gas system seen in today's automobiles and in some experimental airplanes.
Hutterer explains that hybrid simply means two different propulsion systems on a single vehicle. In the case of his concept, the two systems are a pusher turboprop engine in the back of the airplane, and a retractable fanjet engine in the nose.
"My initial concept was to lower the noise level and improve safety," Hutterer said. "I knew it would be more efficient and went through the numbers, and the number was 40 percent."
"My thing is to get the prop [off the wing]," Hutterer said. "But then you end up with a single-engine airplane, and what happens when the engine quits. Usually the answer to that question is another engine.
"I'm saying okay, we can put in a backup engine. A cheap jet, if there is such a thing.
"I started modeling this on the computer, and I started noticing that as a pilot, if you use both of these together for takeoff you get about 40 percent more power. The back engine is sized for cruise anyway. That is the main engine...so when you put on this other engine, it is only used for about five minutes. With all that extra power you can get up to 10,000 or 12,000 feet in about three minutes."
With the configuration Hutterer believes he achieves four goals: better safety since there is no asymmetric thrust; better aerodynamics since the wing design is not compromised with engine installations; better performance since each engine is sized specifically for its role; and substantially lower noise levels in the cabin of the airplane.
Overall he projects a 40 percent savings in fuel over conventionally configured aircraft, a corresponding 40 percent reduction in exhaust emissions, and he also believes the concept easily scales from aircraft seating as few as six, to ones that seat 50.
The concept is patented.
"I was kind of surprised when I got the patent," he said. "Over the years everything has been done before. We've had retractable engines in sailplanes.
"This particular combination I would compare to when in 1988 a Northwest airline captain took a suitcase, added wheels and a retractable folding handle. He invented the [roll-aboard]. There was no new technology. The wheel had been invented long ago, and he just put it together. Now I don't think you can buy a suitcase that doesn't have wheels."
Hutterer is seeking investors to help fund development of a flying prototype. He acquired a Cessna 421 to use as a base and is partnering with Air Plains Services of Wellington, Kansas, for the modifications.
The changes include moving the wing, constructing a new tail section to house the turboprop engine, building a new tail, and modifying the nose to house a retracting surplus jet engine. Assuming work begins soon, the somewhat strangely configured aircraft could be flying in 2015.
Hutterer is manning a booth in the Innovations Pavilion at EAA AirVenture Oshkosh 2013. He hopes to attract enough interest so what he believes is a far better way to build business airplanes, can become a reality.