View Full Version : Rule of thumb fudge factor
Slick
July 3rd 06, 10:48 PM
What is the rule of thumb to reduce the L/D when plotting a cross country
flight?
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Half.
Slick wrote:
> What is the rule of thumb to reduce the L/D when plotting a cross country
> flight?
With experience you can evaluate the conditions of the day and adjust
accordingly. If winds are light and lift is good you can use 2000ft
margin to arrive at the next landable location. Even on a good day I
use 85% of the L/D plus a safety margin.
If you examine the flights of experienced pilots they at time appear to
take much larger risks but it is because they can judge the conditions
and anticipate changes that they are able to do this successfully.
Be careful at first as you can get into trouble fast especially on days
where the wind is blowing.
wrote:
> Half.
>
> Slick wrote:
> > What is the rule of thumb to reduce the L/D when plotting a cross country
> > flight?
BTIZ
July 4th 06, 02:14 AM
1/2 the planned L/d
BT
"Slick" > wrote in message
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> What is the rule of thumb to reduce the L/D when plotting a cross country
> flight?
>
>
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Eric Greenwell[_1_]
July 4th 06, 02:39 AM
Slick wrote:
> What is the rule of thumb to reduce the L/D when plotting a cross country
> flight?
My experience with gliders ranging from a Ka-6e to an ASH 26 E is a
McCready setting of 4 on the glide calculator gives me a very high
probablity of making it to my selected landing place (usually an
airport). I don't set the speed-to-fly at 4, but at 2 or less, depending
on the conditions. My arrival height setting is 1000 feet agl.
In areas with poor landing possibilities, like a glide over a forest,
lake, and other unlandable areas, I'll increase the MC setting to 5,
perhaps even 6. If wave is about, it can be a real guessing game, and
I'll generally use even higher settings. A setting of 4 is about 60% of
maximum L/D.
Be sure your planning allows for the usual winds.
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Eric Greenwell - Washington State, USA
www.motorglider.org - Download "A Guide to Self-launching Sailplane
Operation"
Jean
July 4th 06, 05:13 PM
I use 2 different calculations:
- Safety to reach a landable field: Typically 1/2, plus or minus according
to the wind
- Realistic transition (where a miss wouldn't be dangerous): 2/3
Jean
"Slick" > a écrit dans le message de news:
...
> What is the rule of thumb to reduce the L/D when plotting a cross country
> flight?
>
>
>
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