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L/D of Virgin Atlantic GlobalFlyer
The subject says it all. Has anybody found information about L/D of
GlobalFlyer? My guess is that Steve knows it, because he is also known as glider pilot. Regards, Mika Koski |
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L/D of Virgin Atlantic GlobalFlyer
There was an article in Popular Mechanics I found on the web that
claims that the GlobalFlyer has "a lift-to-drag ratio of 37-to-1--topping even the Voyager's 27-to-1" (http://www.popularmechanics.com/scie...tml?page=3&c=y). There was another interesting piece of information on the GlobalFlyer website in an article (http://www.globalflyer.com/ScienceAv...ilotsView2.jsp) by Jon Krakow, the GlobalFlyer's chief engineer: "One of the characteristics of the aircraft is that it glides well. It glides so well that with the gear up and at light weights with the engine at idle, it cannot descend. Switching to ground idle helps reduce the idle thrust, but to descend at a normal 3-degree glide angle, the gear must be extended and the drag chutes deployed." Scaled Composite's website (Burt Rutan's shop - the designer/builder of the GlobalFlyer, the Voyager and the SpacShipOne) can be found he http://www.scaled.com Looks like on a final glide the GlobalFlyer would beat more familiar gliders such as a Grob 103 or an ASK 21... And you got a beefy self-launcher in case you blow it... Markus |
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L/D of Virgin Atlantic GlobalFlyer
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L/D of Virgin Atlantic GlobalFlyer
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? Marc |
#5
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L/D of Virgin Atlantic GlobalFlyer
On Sun, 12 Feb 2006 19:44:42 GMT, Marc Ramsey
wrote: 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? Any current airliner features an L/D better than 20:1 with engines off. Looking at the GlobalFlyers aspect ratio and design, I get the impression that it's probably even better than 37:1. Bye Andreas |
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L/D of Virgin Atlantic GlobalFlyer
Andreas Maurer wrote:
Any current airliner features an L/D better than 20:1 with engines off. Cite? Jack |
#7
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L/D of Virgin Atlantic GlobalFlyer
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. -- Bruce | 41.1670S | \ spoken | -+- Hoult | 174.8263E | /\ here. | ----------O---------- |
#8
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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 |
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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. Maybe they were factoring in a headwind. |
#10
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L/D of Virgin Atlantic GlobalFlyer
On the global flyers website, it says that it was sensitive to turbulance, at it might cause structual failure (certainly whilst full of fuel anyway!) so maybe a bumpy ridge or rotor may not be that fun...! It certainly looks better than ETA though. |
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