Paul, In gliding I was brought up on the notion of adding 1/2 the headwind
component to the best glide angle speed, although for high winds (amounting
to a major proportion of the best still air glide angle speed), the best
addition is nearer 3/4 wind speed. Quite how you extrapolate that to power
flying is a different matter all together! My copy of Darrol Stinton's book
says that for piston engined planes the optimal range is very close to best
L/D speed, although curiously rather different for jet planes. It's easy
enough to work out the best L/D speed with the prop idling, but it must be
something quite different without the drag of the prop. Fuel flow tests I
helped William Mills do on his Classic 912S at 7000 ft showed Nm/litre
dropping progressively from 8.2 at 100 kts to 7.3 at 130 kts. In my own 914
XS I once accompanied a 90 kt plane to Le Touquet and back and barely seemed
to use any fuel at all, although it did seem to take an awful long time to
get there!
Regards, David Joyce, G-XSDJ
----- Original Message -----
Sent: Thursday, July 13, 2006 2:08 PM
<paul.mcallister@qia.net>
>
> Hi all,
>
> I need to profess ignorance on this topic. My question has two parts.
> Firstly is the maximum endurance achieved at the best L/D speed ? Without
> getting Mr. Dykin's book out I seem to recall that was around 80 ~ 90
knots.
>
> For the second part of the question. Is my max range in a head wind
> situation achieved at the best L/D plus the head wind component ? So for
> example I wanted to get the most out of my tank of fuel and I had a head
> wind component of 20 knots, should I fly at the best L/D plus 20 knots.
>
> Paul
>
>
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