“Flying By the Numbers”
Our EAA Chapter 92 speaker for March 2009 is Captain Bill Moyle. Bill is a 13,000+ hour multiengine turbine pilot flying Boeing 727 series and Douglas DC-8 series airplanes during his airline career. Bill also has couple of credentials of interest to the topic including: Citation Program Manager at Flight Safety International’s Long Beach, CA facility and FAA Safety Team (FAAST) Representative. Bill is great at turning wrenches on airplanes, via his experience courtesy of the USAF in Vietnam.
Bill’s topic is timely. We are coming into good flying weather and some of us are working on eliminating the rust from our winter hibernation from flying. We have all heard the great debate; stick/yoke managing airspeed vs. altitude. This debate has gone on since the third pilot came on the scene flying an airplane. The first two pilots Orville and Wilbur Wright were in complete agreement on how to fly an airplane.
The Bishop’s Boys knew they were power constrained (12 hp was considered high performance in 1903-1904) and at the limit of their power. Back at Dayton, OH trying to fly the next summer (1904), the rebuilt 1903 “Flyer” even refused to lift off for them. This was the first practical encounter with what we call density-altitude today. The flying field in Dayton (now Wright-Patterson AFB) is just over 800’ MSL. The Wrights found out empirically, the Flyer had a service ceiling of less than 800’ PA. If anyone knew about the concept of “Attitude + Power = Performance” it was the Wright Brothers. They just didn’t have it “packaged” in a simple formula, like we do today.
In the early days of aviation the Wrights commented about the “Fancy Fliers”; pilots who pulled back on the stick to maintain altitude. The Wrights knew these pilots were changing the airplane’s angle of attack to hold altitude. With limited power available, a pilot at the edge of the performance envelope is inviting a stall and most likely a spin, if the controls are not coordinated. With the instability and inadequacy of the early airplane designs, this was not the best way to operate an airplane. Spin recovery techniques were unheard at the time, let alone any knowledge of how to maneuver out of one. The Wrights knew all about “well digging”, which was their term for a stall-spin event close to the ground. Their experiments with the 1902 gliders convinced them to eventually add “coupled” and later “independent” rudder control to coordinate their turns. Again, all of this stemmed from their empirical seat of the pants flying with an engineering analysis and review after the lengthy repair and rebuilding process. Today we engage in a “post-flight” test review for a new design or craft.
When you have excess power and a very slippery designed airplane, or you have low wing loading, getting away with maneuvering without adding power can be achieved initially, but it will catch-up to the unwary pilot in the long run. When flying a light stick-loaded (low stick force gradient per G) airplane, like most of our higher performance experimental designs, BEWARE; you may be operating close to the performance envelope. You are inviting a stinging snap-role or at least a departure into an incipient spin due to mismangement That is one of the reasons the EAA encourages a session with a Flight Advisor before you venture off for a first flight.
We have also heard “pitch, power and trim” beat into our brains by our primary flight instructors. This information is published by the FAA in the “Flight Training Handbook”. While correct, taken literally without additional thought and poor trim skills, this technique can bite you. Consider the following as an alternative:
- Fly a trimmed airplane - allowing the pilot to remove his/her hands from the controls;
- The trimmed airplane will continue straight ahead level flight without a climb or descent.
- If you are climbing or descending (no power change), you were not trimmed and were holding control force against the elevator.
- Note your airspeed and power setting (we’ll get to configuration changes in a future article)
- Roll into a shallow turn and add a little power to maintain your altitude
- If you add the right amount of power in the turn, you will neither climb or descent
You will also note you DIDN’T have to re-trim the airplane. You just saved yourself some work (less distraction in the cockpit) and became a manager in the process. This is an example of the technique of “Flying by the Numbers”.
- When you attain your desired heading roll out and reduce power to the original setting.
- You have now flown “By the Numbers”.
It is that simple! The airplane is a repeatable and predictable machine – that is how we can build simulators. If you set the machine up properly (by the numbers), you can perform these maneuvers until a low fuel warning.
This technique is especially important when flying approaches or low level maneuvering. You trim the airplane for the desired airspeed and manage the glide slope with power. You can fly any and all airplanes with this technique and look like you have hundreds of hours in make and model. Very sophisticated autopilot systems fly this way with dual parameters. Simple autopilots use the reverse technique. Decoupling a single pitch control autopilot close to the ground can leave you with a big surprise.
The benefit of flying with this technique is that if the power plant fails and you are “Dead Stick”, all you have to do is go along for the ride at your selected and trimmed airspeed. While you may land short, you will be “flying”, which increases your chances of survival in the event of an off-field arrival.
Bill will provide more information on “flying by the numbers” and keeping the airplane with the pointy side up on landings. Have fun with your new technique.
Keep ‘em Flying
Ray Hecker
EAA Chapter 92 Flight Advisor
CFII, MEI, AGI & IGI
FAAST Representative (Aviation Safety Counselor)