Death Cruiser Flight Crew
Join Date: Jun 2001
Location: Vaucluse, France.
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Sorry sir.pratt, but with regard to the effect of weight (now known as mass) mm_flynn's is the correct answer.
I have dusted off my thirty-five year old copy of the BLAC Manual of Flying and Ground Training, and turned to the chapter on Descending. Section 2.5 reads: "Effect of Weight on the Glide. Variation in the weight does not affect the gliding angle, provided that the speed is adjusted to fit the A.U.W." It then shows the vector diagram to prove that the increased speed vector, acting down the inclined plane, is balanced by the increased weight vector, acting vertically.
The obverse side of this is the fact that, for any fixed airspeed, a heavier aeroplane will have a lesser gliding angle. This is why high performance sailplanes carry water ballast and a lightly loaded jet transport aircraft will take considerably less distance to descend from altitude compared with when it is heavy, given the same speed profile.
The lucky people in the Cherokee were therefore slightly better placed by being three up, the opposite of what some people might think!