Page 23 - Nov24

With great trepidation, the stall tests were initiated. Fearing what might be found, the test airplane had the standard tail cone replaced with one that housed an explosively deployed drag chute. As the stall series progressed, moving from forward to aft CG, lead test pilot Bud Francis found that everything was quite conventional. Although the burble from the wing missed hitting the high horizontal tail such that there was very little pre-stall buffet—making the stall horn a requirement—every time the stall break occurred, the nose dropped at its own accord. But as the CG finally reached the aft limit, Bud related that not only did the nose not automatically drop at the stall break but it pitched up about 10 degrees higher! “Thank goodness for the chute!” he said silently.
But, voila! When he pushed the wheel forward, the nose came down and recovery was easy. This led to a statement made in the “Associated Conditions” portion of the Stall Speed chart that carries more significance than most readers realize. It goes something like this: “A normal stall recovery technique may be used. The best procedure is a brisk forward motion of the control wheel to a full nose down position. Recovery should be initiated when airspeed has increased approximately 20 knots above stall speed.” So the shaker and pusher went away, found not to be required.
It was thought that this new big rudder might well require more than 150 pounds—the FAA maximum allowable—to fully deflect, and hence the installation of the rudder boost system on the prototypes. The final tests showed the actual worst-case force to be 147 pounds, so the rudder boost also could be eliminated. However, it was retained as standard equipment since Beechcraft airplanes are supposed to be the “Cadillacs of the Air” and who wanted to apply that much force anyway? However, the MMEL (master minimum equipment list) allows operation without a rudder boost in the 200 series. (Not in the 300 series, where the maximum force can reach about 180 pounds.)
A few other benefits were found to follow the T-tail. First, there was much less pitch trim involved when the flap position was altered since the changed airflow from the wing mostly missed the tail. Second, the airplane was smoother in flight and during ground run-ups since the prop wash wasn’t hitting the tail. Lastly, and perhaps most beneficial, by moving the horizontal stabilizer up it was also being moved aft due to the sweep of the vertical tail, which led to a longer moment arm to the elevators. Now, with a much smaller horizontal surface than on the 100, they could revert to simple conventional trim tabs on the elevators and achieve a 4-inch greater CG range for the same cabin dimensions! Amazing!
NOVEMBER 2024
KING AIR MAGAZINE • 21