Plane & Pilot
Tuesday, April 21, 2009

Looking For 200 Knots

Forty years ago, the goal was 200 mph. Today, it’s 200 knots.

knottsFast feels good. For those of us obsessed with clocking along at the velocity of a Lamborghini, speed is the kinesthetic equivalent of beauty.
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F8F Bearcat Rare Bear
The turbocharged Corvalis benefits from the same engine as the Acclaim S, but it’s rated for 310 hp rather than the Mooney’s 280. TBO remains 2,000 hours, and Cessna claims a cruise of 235 knots at 25,000 feet—with fixed gear.

The Cirrus SR22 TN easily races along at better than 215 knots up high, 200 knots down low. Cirrus’s SR22 TN employs the identical engine rated for the same horsepower, but boosted by a turbonormalizer produced by Tornado Alley Turbo ( of Ada, Okla. The brainchild of Alan and Dale Klapmeier, the Cirrus features all-composite construction plus a whole-plane parachute, the latter is a feature none of the other models offer.

The Cirrus’ combination of a clean design and essentially the same 310 hp Continental IO-550 engine results in an optimum cruise speed of nearly 220 knots, making it easily competitive with the Acclaim S and 400TT.

Semi-finally, the venerable Piper Malibu and Mirage have been 200+ knot airplanes since the type’s introduction 25 years ago, longer than any of the others. The new Piper Matrix, at its roots a depressurized Mirage, is the latest airplane to join the 200+ club.

The Malibu represents the old order of 200-knot machines. Introduced in 1984, it was the result of the dedicated efforts of a design team led by aerodynamicist Jim Griswold. The original Malibu featured a roughly circular fuselage, designed from the outset for pressurization and high-altitude operation. Better still, there was no taper, as the fuselage translated aft, so all six occupants enjoyed the same head and elbow room.

The Malibu first flew with a Continental TSIO-520-BE engine churning out the familiar 310 hp, and once again, the fuselage and wing were as slick as Piper could make them. The wing was 43 feet wide (try fitting that into a standard T-hangar), designed with a relatively short chord to provide a glider-like high aspect ratio, and optimized for high-altitude flight.

Piper’s original spec for the Malibu was 216 knots, and most of the airplanes would reach that number in the thin air at FL250. The newer, heavier, post-1989 Lycoming-powered Mirage features 350 hp and can manage more like 213 knots.

Perhaps equally impressive to many of the older folks who can afford the currently million-dollar Mirage is the fact that the airplane’s 5.5 psi pressurization system allows the airplane to fly at nearly 200 knots at 12,500 feet, where the cabin altitude is still practically at sea level. Similarly, the Malibu/Mirage offers a six-seat, semi-cabin-class environment with a double-clamshell door for entry/exit.

The Piper Matrix enjoys all the benefits of the Mirage except the inflatable cabin and offers a lower empty weight, improving payload. Cruise speed is in the same class, 210 to 215 knots, with almost 200 knots available at 17,500 feet.

Despite the above, not everyone is willing to pay the penalties associated with flying fast. Climb can be laborious and subject to ATC step-ups; all the aformentioned models burn between 19 and 22 gph at high cruise, and engine-overhaul shops suggest that engines run at max cruise and high altitude have less chance of making TBO. Still, there’s little question that speed sells. For many pilots, speed isn’t the most important thing. It’s the only thing.


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