Originally Posted by
Planespotta
Forget a published airspeed - L/Dmax is what you are aiming for, and because of this, Vglide is hardly ever its published value. I have always been taught (and will teach) to change speed when you have a head or tailwind. This has been confirmed by every DPE (4-5) I've asked about the subject, for whatever that's worth. You are trying to glide a certain distance over the ground, and hence your indicated airspeed should be adjusted to obtain a groundspeed that will produce favorable results.
Ever lesser known is to decrease Vglide by 5% for every 10% below max gross weight. Just a handy and surprisingly accurate rule of thumb. Make sure you know if Vglide has been calculated with or with out flaps, gear, etc., too.
Spotta,
Interesting enough (L/D)max will
only produce best glide in no-wind conditions. The change in the indicated airspeed changes the L/D. My understanding is that for best range the object is to lessen the time effect of an adverse wind condition (as it will relate to glide speed) - so increase the airspeed.
The airspeed/weight/wind for glide calculation is also a bit interesting and sorta ties into what you said.
- No wind - weight has no effect on range
- Tail wind - jettison weight for best range
- Head wind - retain weight for best range