John All of that would be true in level coordinated flight. But in a slipping descent as in ANY maneuver while DESCENDING, IF a pilot does NOT attempt to remain level, but rather continues the descent, than the maneuver does NOT increase the load factor on the wings. Load factor is what increases the stall speed. The descent has already reduced the angle of attack. This is why you are descending in the first place; lack of enough lift to remain in level flight. What killed those pilots you spoke of is the classic crossed controlled stall, usually on the base to final turn, but could happen at any point, where the airspeed appears to be high enough, due to what Larry pointed out, a misalignment to the relative wind, as compared to normal flight. The exposing of the fuselage side to the relative wind causes an increase in drag, which if the nose is not lowered to counter, can cause a TREMENDOUS loss of airspeed quickly. A Tiger Moth has the added problem of being a biplane, already with a high drag configuration, and limited visibility, so the sight picture during the approach is aggravated, by being blocked more. Increasing airspeed will only undo what the slip is doing for you. Adding POWER to assist in maintaining the same airspeed may make it easier, but will make the transition tricky, especially if you happen to forget about the added power.
There are two primary reasons that commercial aircraft crab way down final, and then "kickout" into the sideslip touchdown: 1) Passengers do NOT like to be pointed at the ground! That is a big NO NO! Big bank angles when on final, or while descending is gaurunteed to get the "You can't fly, worst landing I ever had"! remarks from de-planing passengers 2) Many air carrier aircraft cannot lower the wing enough to compensate for the higher winds on final and still clear the ground with the engines or wingtips. The volume of buildings and surface friction tend to lower the surface winds, so that the large plane can lower its wing enough during the "kickout" procedure. So they crab until just before touchdown, then "kickout" into the sideslip to take advantage of the slower windspeed, and quick touchdown where the wheels will take over directional control. Thrust reversing and spoilers make sure that the aircraft remains controllable by slowing quickly and reducing lift even more. Since we don't have these devices, "kickouts" are tricky and not recommended for lower hour pilots. Although it is a procedure that commercial pilots, even for single engine rating are taught to add to their bag of tricks, other pilots are normally not taught, and are discouraged from using it. The FAA prefers using what they call a stabilized approach. That is, crab for correction at all times while in normal flight, except on short final. When established on final, and still at approximately 200 to 300 feet off the ground, transition smoothly from the crab correction, to a wing low stabilized attitude, and maintain this attitude with corrections as the wind changes, until touchdown, and all wheels are down, and then transition into the appropriate taxiing wind correction until shutdown. Ken Jones: Thanks for the heads up! Went to the wrong FAR/AIM! Got to throw that one away! Colin M Rainey First National Mortgage Sources Lending Solutions in All 50 States 386-673-6814 o 407-739-0834 c co...@firstnationalmortgage.org
