NavList:
A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
From: Robert VanderPol II
Date: 2017 Jul 28, 15:59 -0700
A July landing would have led to an earlier touch down, the higher temp and lower air pressure would have decreased total lift and lead to a greater sink rate and glide angle, though as previously mentioned the IAS for optimum glide might stay the same.
There is no way to achieve a zero kinetic energy touch down. Zero kinetic energy means zero speed. If you pitch the aircraft up you increase drag, but then that falls off as the speed decreases, at somepoint you stall, lose lift and fall. If you stall the aircrat at altitude you could probably eliminate most of the forward motion of the aircrarft at the cost of increasing the vertical speed at time of impact. Also you might create a situation where the aircraft tumbles. I you just keep pitching the aircraft up while just above the water at some point it will stall and start tumbling since the tail will hit first, then you have a bunch of really short but very sharp vertical accelerations.
The ditching that actually happened was pretty close to optimum. Aircraft was almost stalling or may have started stalling when it hit so it was at or very near minimum possible forward speed. There was little vertical speed when it hit so folks were less likely the experience high vertical accelerations. By hitting nose first it presented less area to the water in the direction of travel, so there was less acceleration in the horizontal direction. The plane took several hundred feet to decelerate to a stop meaning accelerations on the passengers were minimized.
Re: Miracle on the Hudson
From: Herbert Prinz
Date: 2017 Jul 28, 13:36 -0700I don't believe what you are saying. There must be a way of dissipating energy while still in the air, by changing the angle of attack, or changing air resistance with flaps or whatever. Otherwise, how could a glider ever land safely? Gary was merely speaking about the optimum angle of attack with respect to gaining maximum distance. I see no reason why the plane could in theory not have touched the water with zero kinetic energy left.
