L/D of Virgin Atlantic GlobalFlyer

Bruce Hoult wrote:
In article ,
Marc Ramsey wrote:

Bruce Hoult wrote:
And yet they said yesterday that if he ran out of fuel he could glide
200 miles from 50,000 ft. Which is 24:1, assuming nautical miles.
Which makes one suspect that the 37:1 is with the engine idling, not
dead.
If someone was going to tow you out to sea in your Standard Cirrus,
would you determine how far you can glide back based on the
manufacturers advertised 37:1 glide ratio, or perhaps something a bit
more reasonable like, say, 24:1?

From 50,000 ft? If I was going for a world record and had a parachute,
people standing by to pick me up, and a wealthy backer? I would expect
that the probability of sink the whole way would be vanishingly low and
that working on 32:1 or 33:1 would be pretty safe but that there would
be a pretty good chance of using what atmospheric variation was
available to manage a good bit better than the glider's raw glide angle.

It was pretty late in the day when he landed at Bournemouth and would
have been later still at Manston. Good glider or not, I wouldn't count
more than still air, with maybe a bit of added sink, at that time of day.

BTW I agree it would be interesting to see how it performed as a glider.
Let's see now:
- restricted vis - I wouldn't want to share airspace with it
- it might run a cloud street, but could it turn tight enough to
core a thermal?
- with a design cruise of 250kts, it may be too fast to use
anything but wave or ridge lift.
- Anybody fancy running the Appalachians in it? A two hour 750
should be on in theory.

--
martin@ | Martin Gregorie
gregorie. |
org | Zappa fan & glider pilot