Plane & Pilot
Tuesday, May 7, 2013

Prius With Wings

Two-fisted thermal grabber, fuel-sipping cruiser and trainer—in one airplane!

The bird enjoys the gift of a 30:1 glide ratio and 202 fpm sink rate from that high-aspect-ratio (18.3:1) wing—excellent soaring potential. What makes the Sinus a fairly remarkable motorglider, though, is its long range and fuel-sipping personality. Vollmer, round-tripping to Oshkosh Airventure last year, averaged under three gallons per hour.

That economy comes from two prime origins: 1) gorgeous, clean aerodynamics, even though the landing gear (tailwheel or optional trike) live in the slipstream, and 2) the 80 hp Rotax 912 UL engine, which turns a 15-gallon (26 gallons optional) fuel load into an impressive range 650 nm (or 890 nm) reach.

And that's at a cruising speed around 110 knots. Many S-LSA don't cruise that fast...and on 100 hp! And that's at MTOW: Rand Vollmer and I weigh in at close to 400 pounds of passenger/clothing payload, yet right now, we're humming along at 105 knots on 4,800 rpm. And that's at full fuel (26 gallons), with 44 pounds of baggage more possible—max MTOW is 1,210 pounds.

The load factor spec is +4/-2G. Max tested load factor was +7.2/-7.2G! Strength doesn't take a backseat to performance at Pipistrel.

Considering those power specs, you'd be tempted as I was to conclude Sinus is a tad underpowered. Au contraire! In our climb from sea level to angels 8.5, we throttled back to a cruise climb of 80 knots at around 4,800 rpm. Our climb rate was still nearly 800 fpm! Another time, climbing from 6,500 to 8,500 to cross the ocean en route to Cedar Creek, Fla., we ran at 4,400 rpm at 90 knots. Climb rate? Better than 400 fpm.

Pipistrel specs max climb at an impressive 1,280 fpm at 65 knots...but still 1,240 fpm at 84 knots! We didn't quite reach the top value—it was a 70-degree day—but I saw 1,100 fpm, and our optional trike gear is more draggy than the standard tailwheel version.

Labels: LSAsPiston Singles


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