28 Oct to 8 Dec 2012
Here is an update on my flying. I’ve been flying the AT-6 in a military certification program and the Baron for trips. The Baron trips have been basic flying, but the AT-6 has been all flight test. We just finished the flutter envelope expansion for all the stores and have moved into engine certification.
In flutter envelope expansion, you take the aircraft to the limits in Mach and airspeed and ensure there are no adverse dynamic problems with the aircraft. Additionally, we have evaluated the high speed handling characteristics along with other detailed certifications. The AT-6 chews up everything you can throw at it and spits it out. It is easy to fly at the limits of the envelope, but that doesn’t mean it is easy to get to those limits. That’s what makes the aircraft inherently safe and predictable for the pilots. It takes a lot of planning to get a really draggy configuration out to the limits of speed. In the field, a pilot will not see those limits. If he or she does, the aircraft will not just handle it, it will be responsive and safe. Some of the limit points require taking the aircraft above the altitude limits and making a very steep dive to achieve the desired Mach and speeds. When I flew operations, I would never think of trying to get an aircraft there. To get the data for flight test, you have to hold the conditions for an extended length of time. Additionally, the pilot will receive warnings when he or she reaches those limits. For flight test, we shut off the warnings so the pilot would not have to contend with "bitching Betty" while trying to hold the limits. Also at the end of each high speed run, we pulled the aircraft into a high G recovery to gain altitude and to set up for the next point. Literally, during the tests, I went from a face full of ground to a face full of the heavens. During flutter certification, we made stick raps and had flutter exciters on the wingtips. The flutter exciters ran in symmetric and antisymmetric modes to excite the vibrations on the aircraft. On the ground, the vibrators in the wingtips would make the entire aircraft shake. I was hoping to get a little vibration during flight to ease my weary back. In the air, however, most of the vibration gets absorbed by the airloads–oh well.
For engine certification, you check out everything on the ground and then take the aircraft to various altitudes and basically abuse the engine in ways few pilots would even try. The engine just keeps ticking. It is perfectly carefree and reliable. During the last three days of testing, the weatherman was completely wrong about the weather, and I had to fly approaches to minimums to get the aircraft back to base. The problem is that our test boom is supposed to be kept dry (not flown through clouds). You can’t fly an approach in the weather without being in the clouds. The AT-6 has the same awesome navigation systems as the T-6, with the addition of WAAS GPS. So, on the AT-6, we can fly even more approaches and get to lower minimums than most military aircraft. All in all, flight testing the AT-6 is a great experience. It is really an outstanding aircraft.
I’ll try to keep you updated on the flying–and the flying is great.