ths@lanl.ARPA (09/24/85)
Well I sure received a bunch of replies to my question about what causes an airplane to climb in a constant airspeed ascent. I also added some fuel to the fire when I used the term "all fources are equal" instead of "all forces are in equalibrium". The "trick" in the question is simply that few text books for the private and commercial pilot discuss this aspect of flight. It has only been in recent years that Jeppesen has paid more attention to the drag curve, but they still don't adequately explain the relationship of the four forces. I received a number of interesting explanations ( and a few unfriendly comments) but the bottom line is the "the vertical component of thrust" as explained so effectively by Oscar Strohacker. Going on the Cessna flap (no pun intended), the official statement by Cessna was that with 40 degrees of flap at gross weight, the aircraft had little if any ability to climb. This situation tended to get some pilots into trouble during a go-around or if the flaps became inoperative in the fully extended position. The Cessna flap is so effective that reducing the travel to 30 degrees did not significantly degrade the landing performance which was outstanding to begin with. I believe only the 172 has the notice in the handbook about "avoiding" slips with full flaps extended. It does not actually "prohibit" slips. With respect to "dropping the nose" in lieu of slipping with full flaps, this can be used effectively. HOWEVER, my experience with Many Many pilots is that they arrive in the flare with an excess of 10 knots or greater airspeed. If they were trying to execute or demonstrate a short field landing they will then try to force the airplane onto the runway resulting in wheelbarrowing and/or porposing. My suggestion is to use the most appropriate technique and if you grossly misjudged, demonstrate a full-flap go-around. Ted