On Wednesday, April 15, 2020 at 11:48:48 PM UTC-7, 2G wrote:
On Wednesday, April 15, 2020 at 4:10:28 PM UTC-7, Eric Greenwell wrote:
Dan Marotta wrote on 4/15/2020 2:30 PM:
You're right, Tom.

I recall the time we got low over an airport about 60 nm from home. Rather than
land, I started the engine and discovered that we were low on fuel.Â* Rather than
give up, I climbed straight ahead under power, watching the glide back to the
airport, until I had a certain glide home.Â* I had enough fuel, though not enough
to make me comfortable.Â* I now won't take off with less than about 3/8 of a tank,
or about 12 gallons.

On 4/14/2020 7:38 PM, 2G wrote:
When you are flying a motorglider the FAA considers it to be a glider and fuel
reserves don't apply. The point is that planning launches or retrieves w/o
factoring in reserves is a bad idea. You will NEVER get the promised performance
for a variety of reasons. It would be like planning a final glide using the max
L/D.

Tom

Contest pilots often start their final glide even lower than a max L/D glide, when
they know the conditions on the way to the airport have some rising air.. Uvalde is
well-known for that kind of planning. I don't think it is always necessary to
factor in reserves, either, as long as you have a safe place to land if it doesn't
work out. That seems to be what Dan did: not enough fuel to provide an adequate
reserve, but a bail-out plan if he didn't get lucky.

I do agree with your point in general, however, which applies to all glider
flying, powered or not.

--
Eric Greenwell - Washington State, USA (change ".netto" to ".us" to email me)
- "A Guide to Self-Launching Sailplane Operation"
https://sites.google.com/site/motorg...ad-the-guide-1

I don't worry about what "contest" pilots do - they are trying to win a contest. I would NEVER plan a glide at best L/D where the consequences are a crash - and neither should you or anybody else.

Difficult to state maxims about XC flying, but I would think most western flyers start their final glide before the computer says you have the numbers.. If you have been flying though lift the entire day, why wouldn't you take into consideration the amount of lift you are likely to hit on the way home. Now if the air is getting still and the day dying, one should not plan on finding additional lift. There is rarely a right answer in xc soaring, but there can definitely be a wrong answer.