Plane & Pilot
Tuesday, November 6, 2012

Light-Sport Chronicles: The Wizards of Alpha


Insider glimpses of Pipistrel’s sky-breaking new trainer


Flight Design and other composite makers have had to deal with this challenge, too. "Fuel tanks are the biggest weakness in a lot of LSA designs," says Michael. "For the Alpha, we built a special standalone fuel tank, with coatings made by the Rhino company. Rhino does liners for pickup truck beds. The coatings are impervious to ethanol and other fuel additives. And the beauty of the system is that the 15-gallon tank is mounted in such a way that there's very little chance of rupture even in a very bad crash. The tank is designed to absorb impacts from a variety of directions, too."

Much ado has been made of Alpha's beefed-up undercarriage. "We redesigned the nose leg. It's shortened for better forward visibility for shorter pilots. We also reduced the angle so it's more vertical. That increases its strength by 140%. Now, even if you pancake the plane into the ground, impact forces transfer into the engine mount and shock absorber, where they're designed to go, rather than pushing the undercarriage forward into the prop.

"They really did some hard thinking about this aircraft," he says, wrapping up our talk. "The prototype had negative flaps for cruise drag reduction. That can be confusing for a new student, so we simplified it back to three settings."

The usual max flap limit on other Pipistrel models has been around 18 degrees; with Alpha it's 25. Another design consideration was making sure the slippery airframe didn't permit flight beyond the 120-knot LSA full-throttle limit. Special wingtip design created greater drag at higher speeds, in congress with the proprietary Pipistrel wooden/aluminum prop. The tips also create greater drag with flaps deployed, which helps degrade glide ratio. Otherwise, this clean glider-like bird would ride ground effect for quite a ways.

Another note on the prop: Since it's made in house, the fiberglass-covered wood core fan only costs $350 to replace. Compare that to the typical $1,000-plus price tag for other LSA props.

I'm betting you'll see Alphas showing up all over the country in the next couple years. Michael Coates and his ever-growing network of Pipistrel dealers are doing their best to make sure you do.



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