Saturday, May 1, 2004
Tradewind Turbine Bonanza
Adding more power to a Beech A36 translates to more speed and fun
Putting It To The Test
Starting a turbine is a little different from revving up a piston-powered engine. There is no priming or any of the tasks you need to do to coax the cold engine to life. Get the igniters going, engage the starter and give it some fuel. As the engine goes up to speed, watch the temperatures and switch the generator on line at idle. Simple. Just make sure there’s plenty of juice in the battery.
Taxiing is different in this plane, as well. Slip the prop out of Beta and the airplane will run briskly down the taxiway. Instead of brakes, just slip it back into Beta pitch to slow down. Forget about checking the magnetos; just line up on the runway and pour on the coals. Be careful about throwing in a bootful of rudder to counter the torque. It won’t need much. And be prepared to sit back in your seat because the acceleration is impressive.
During takeoff, there are two things you don’t want to do—over-torque the engine and over-speed the gear. A turbine operates using a percentage of rpm and torque, which is essentially the twist value as felt by the prop-shaft. At lower altitudes, think of torque as the red-line, not rpm. If you exceed it, you risk damaging the engine. And, yes, there’s enough power to accelerate quickly through your gear operating limits. Normally, gear speed for general-aviation airplanes only is a problem during the descent, but in the Turbines A36, if you don’t watch your pitch attitude, it comes along very quickly.
Cruise speed in the Turbines A36 also is impressive. At 25 degrees nose-high, the airplane will peg the VSI all the way to cruise altitude. For most airplanes, this is, essentially, an aerobatic maneuver. Plus, the Turbines A36’s yellow line really is the limitation for the airplane, not the lack of engine power. And the 65 db of noise level at cruise, according to Boyd, is much quieter than a piston.
For descents, you can go down as fast as your passengers will let you, just flatten the prop pitch. Mixing it up with the big boys at the bigger airports also is easier. Increase your speed, slow down or do whatever you need to do—fast and smooth are the watchwords.
But all this performance doesn’t come for free. After you put the Allison engine on the airplane, you have to feed it on the order of 28 gallons per hour. The 20-gallon tip tanks make up for some of its prodigious appetite, but with IFR reserves, it doesn’t quite have the range of a normally powered airplane. The simple truth is four hours is the upper limit for most passengers anyway. In a Turbines Bonanza, you’ll be able to go about 25% farther than in a piston-powered airplane in the same time period.
So, let’s see. One hundred times safer than a piston, the same comforts as a luxury airplane and easier flying and maintenance.... This Tradewind Turbines Bonanza can certainly show us that the sky is the limit.
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Labels: Turbine Twins