Hello all,
I have a question regarding the notion of "pushing" down to extend a glide. As far as I knew, the only way to obtain the max power off glide range was to stick to the best glide speed (eventually adjusted for weight, wind, bank, density, ect).
However after flying in a Piper cub with a fellow instructor, he argued that when trying to extend the glide to clear an obstacle, you should "push down" pointing the aircraft straight towards the obstruction and then pull-up at the last minute in a zoom climb to clear the obstacle. When pushing down, the aircraft will be flying at a speed higher than best glide.
To me the above reasoning does not make sense. If you fly at the speed that gives you [L/D]max you should get the most efficient convesion of altitude into range. Any speed higher or lower than best glide should decrease your glide range. (hence the name best glide
)
Furthermore, any time you trade airspeed for altitude (and vice versa) you always lose energy since the conversion is not 100% efficient. Therefore pushing down to increase speed only to have to have to pull up again later seems like something you wouldn't want to do.
The same instructor claims that glider pilots regularly use this technique to extend their glide a little further and clear an obstacle. He calls it "learning how to push". I only have some 30 flights in a glider, 10 being solo, but I don't recall any of my instructors saying anything about "pushing".
Could somebody shed some light on this topic?
Am I missing something here?
Has anyone else heard of this practice? Is it only an aviation myth or is it actually true? (hopefully the explanation is more convincing though)
Could it be that this presumebly-incorrect notion of "pushing" to extend the glide has its roots in the fact that it may be necessary to "push" the nose down in the event of an engine failure after takeoff in order to accelerate to best glide speed and maintain an adequate stall protection margin? (assuming your climb speed was below best glide speed) Some people might have misunderstood this and believe that pushing down will extend their glide range.... just a speculation.
Thanks in advance for your replies.
palgia