Thursday, November 1, 2007
Aerostar 702: Still The Fastest
Forty years after its introduction, the Aerostar remains the world’s fastest, general aviation piston airplane—period
Cross-feeding cuts the center tank out of the system, and if you have a total electrical failure with one or both selectors in the cross-feed position, you may have a bit of a problem because there’s no way to change the selector position without electrical power. No matter how much fuel remains in the center tank, you won’t be able to access it in the cross-feed position.
In keeping with Ted Smith’s penchant for electrohydraulic nosewheel steering, the 702 employs what some pilots call thumb steering. There’s a small rocker switch mounted on the center console that provides a power-steering assist. Blipping the switch left or right deflects the nosewheel and even allows you to taxi with one engine shut down, something you couldn’t consider in most asymmetric-thrust, medium twins. It’s possible to taxi without using thumb steering, and most pilots rely on standard asymmetric braking for the actual takeoff once the nosewheel is lined up with the centerline.
Smith’s clean wing was deliberately designed with only one degree of incidence on the ground. If the main gear struts are pumped a little too high, this can translate to a slightly negative angle of attack. That means the airplane won’t fly itself off the runway. You must rotate the wing to a positive angle of attack. Once you establish the proper attitude, clean up the underwing and accelerate to the 117-knot Vy, however, the 702 climbs away at nearly 2,000 fpm.
Better still, though, the airplane’s cruise climb performance is excellent. The recommended high-speed climb is 145 knots, but in delivering a dozen or so 700s around the world over 20 years, I’ve used 160 to 170 knots and still seen an easy 1,200 fpm. Climb holds up well at high altitude, and you can jump from sea level to 25,000 feet in an easy 25 minutes.
Jim Christy likes to brag that the 702 will easily run 261 knots at max cruise. That’s because 261 knots equals 300 mph, and Jim likes round numbers. Yes, the Aerostar will do it. Back in the ’80s, Christy and I worked together on a segment of a TV series, ABC’s Wide World of Flying, and the airplane did indeed run along at exactly 261 KTAS at FL250.
The bad news at high cruise is that fuel burn is close to 25 gallons per engine per hour. Virtually all the Aerostar 700s and 702s have the optional 44-gallon baggage aux tank, so endurance with full tanks and max cruise is about three hours plus reserve, nearly 800 nms between pit stops. The better compromise for long range is 55% power, worth 225 knots in exchange for only 37 gph. That translates to more like 1,000 nm. Of course, if you have to ask how much it costs to run…
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Labels: Piston Twins