While in East Africa in 1970, I had the pleasure of sharing a cockpit with F.W. (Bill) Woodley, the chief game warden for Kenya's mountain national parks. Woodley used a 1965 Piper Super Cub to rescue lost mountain climbers, spot poachers, direct firefighting countermeasures, and conduct law-enforcement activities.
Woodley had a reputation for being an extraordinary mountain pilot. It was said that he could coax performance out of an airplane that exceeded even the optimistic claims of its manufacturer. This included operating the Cub from a short, unimproved strip at the 14,000-foot level of Mt. Kenya and routinely nursing it to substantially above its service ceiling.
My stated purpose in accompanying Woodley on a simulated mountain rescue was to research an article about him for a local magazine. My underlying reason was to determine whether Woodley's reputation was justified or just a fable.
Prior to climbing into the front seat of the Cub, Woodley removed his boots and socks. No, this was not to avoid soiling his pristine airplane. He claimed that this helped him to better feel what the Cub was doing. My skepticism needle pegged.
After departing Nanyuki Airstrip, Woodley pointed the nose toward Mt. Kenya, an extinct volcano that rises abruptly to an elevation of 17,058 feet, the second tallest mountain in Africa.
At 15,000 feet, the Cub's rate of climb was nil, and it appeared that the summit of Mount Kenya was beyond reach. Woodley fine-tuned the fuel-air mixture once again and moved to within less than a wingspan of the mountain's ragged features.
He soon spotted a pair of eagles soaring over the edge of a bluff and moved the Cub in their direction. The birds held their ground as Woodley joined the formation and followed them. We began to climb, hugging the sunlit slope and occasionally lifting a wing to avoid a boulder as we did so. Moments later, we were skimming above the glacier that defined the summit of Mt. Kenya, and the Cub was still climbing.
After returning to Nanyuki, Woodley told me that the techniques he used to milk the last drop of performance from an airplane are not mysterious. "All I do," he said, "is pay attention to my surroundings. There is so much we can learn from the animal kingdom. For pilots, this means studying birds, the masters of soaring flight. They know how to avoid sinking air and take advantage of rising air."
None of this is particularly new to sailplane pilots. Capitalizing on currents and remaining aloft without power assist is a challenge accepted during every flight.
But as Woodley demonstrated, the principles used to sustain the flight of birds and sailplanes also can be applied to improve airplane performance. For example:
- When flying along a valley (narrow or wide) with a crosswind, alter course to the downwind side. This places the aircraft in rising air and, by maintaining altitude, increases cruise airspeed. Those who fly on the upwind side of a valley lose performance even when winds are light.
- Whenever practical, conduct flights along the windward sides of rising terrain and avoid the leeward sides.
- When climb performance after takeoff is likely to be anemic (such as when heavily loaded and/or at high density altitude), visualize how the local wind is influenced by the terrain to determine where up and down currents are most likely to occur. After takeoff, alter course to avoid sinking air and head for rising air.
- Rising air usually can be found beneath cumulus clouds, while sinking air often is found between them.
- Expect the strongest thermals over dry, light-colored, sunlit areas; sinking air is most typically found over terrain that appears moist, darkly colored, or shadowed.
Although power pilots understand these principles, only a few take advantage of them when aircraft performance is marginal. The idea is to establish a mind-set that keeps you aware that these survival tools are available for immediate use. They can even be used during normal flight when additional performance is desired.
Consider a pilot flying VFR on a turbulent summer day. Upon encountering a downdraft, he attempts to maintain altitude by raising the nose and adding power. When flying through an updraft, he maintains altitude by lowering the nose and reducing power to prevent airspeed from becoming excessive. Although these are the accepted procedures for dealing with up- and downdrafts, they prevent us from getting the most out of our airplanes.
Maintaining altitude in a downdraft is counterproductive. Reducing airspeed prolongs the time it takes to pass through the downdraft, which erodes performance further. Also, increasing power at such a time can result in excessive oil and cylinder-head temperatures. The idea is to pass through the downdraft quickly. Instead of attempting to maintain altitude, allow the downdraft to have its way and maintain normal airspeed.
Holding altitude in an updraft makes no sense. Lowering the nose increases airspeed (sometimes too much) and rejects nature's offer of free altitude (which can be used later to offset the loss sustained in a downdraft). And as every pilot knows, it is not wise to defy Mother Nature.
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