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Fuel Loss May Cut Short GlobalFlyer's Journey
chris mazuc writes "Apparently the Virgin Atlantic GlobalFlyer has lost 2,600 lbs of fuel and might be forced to abort the attempt." According to the article, "Jon Karkow from Scaled Composites was unable to say whether it was due to leakage or evaporation. "We really don't know what it is... It's more than likely a system issue, such as a fuel venting line. It's been very puzzling for us, and we saw it quite early on.".
That is about 380 gallons of gas, if you calculate avgas at 6.84 lbs/gallon.
-ted
It was due to a defective fuel guage showing a full tankload, despite it being 2600 lbs short.
Just because you can mod me down, doesn't mean you're right. Shoes for industry!
The article mentioned they will have to decide before departing Japaneese airspace, but you can see from the current posit, they are several uhnder miles off the coast.
Guess they couldn't wait for the news conference. Looks to be a bit east of Japan...
Think of this plane as a one-shot deal. Reusability wasn't the goal -- getting around the world was.
Sure, pilot safety is a consideration -- in some emergency situations, the pilot could probably dump the fuel to land safely. In a worst case scenario, he could probably land with full tanks, but as I mentioned before that might not be without substantial risk to the aircraft. It might even be expected that the plane's airframe would fail if it landed full.
John
I doubt that the plane can land with anything close to a full tank. So, a fully loaded test flight would have been a 60 hour test flight. Doing this on a single seater without the excitement of breaking any records would probably be very dangerous.
That's kinda the nature of breaking a world record, you cannot do a test because the test would break the record.
Jack
Actually they are testing it at full capacity. Right now. If it works, they finish the flight. If it doesn't, they modify the system. If you remember, the voyager only loaded full fuel on it attempt flight. And they pretty much ground off both winglets. Yet, the craft was still ok to fly around the world and set the record. Sometimes you have to take some exucated risks to set records.
When learning to fly a Cessna 150, my instructor always made me not trust the fuel gage since what it reports can safely be confirmed another way -- I'd have to look in the tanks and dip a stick in the fuel to be sure there was enough. When flying, it's a different story as you must trust your instruments.
One other thing I failed to mention in the previous post: the fully laden wings droop substantially, and I believe they almost drag on the ground when full. It would be extremely difficult (if not impossible) to land a craft in a condition like that without accidentally dragging a wingtip.
John
There actually was a case back in 1983 when they loaded a Boeing 767 up with X pounds of fuel when it should have been X kilograms so they were short by a factor of 2.2. Luckily the captain happened to be an experienced glider pilot.
Video and story here
From my observation of the live takeoff video feed from the airport, I didn't see any drooping at all. At the end of RWY 35 where it sat a good portion of the day, the wings looked perfectly level in all shots I saw on the feed - including the moments immediately prior to takeoff. Once the takeoff roll was underway and especially once airborne, the wings appeared to have a slight bend upwards at the tips.
I would bet they have a way to dump extra fuel.
Detachable tanks would also have helped Voyager, but they aren't permitted by the rules; you have to land with all the airframe you took off with (fragments of winglets apparently excepted). If it weren't for this it would be possible to drop tanks, wings and engines like a staged rocket.
Sustainability and energy independence essay
Oh, shoot, that was the previous two-person around-the-world plane that had such droopy wings. Sorry, my error.
John
I read this on the website a while back, and my memory may be rough.
There may be more, but that is what I recall
It is very unlikely that running out of fuel is even a risk. An aborted attempt is the most likely outcome. What most people seem to be missing is this is a test flight.
See my blog http://ilovecookes.blogspot.com/ for light hearted technical information.
Actually, due to a design to keep the structural mass low and due to the mass of the fuel, it can't land safely with a full (or even half) load of fuel.
The plane just isn't strong enough. Making the plane stronger would make it heavier, and a heavier plane would require more fuel. Its a compromise that had to be made.
On a side note, they actually wanted to use a different turbine that was more fuel efficient but, were unable to locate one. So since the turbine they are using consumes more fuel, more compromises had to be made in the design.
With a flight like this, you have to get rid of every last once of weight possible.
----- If communism is a system where the government owns business, what do you call a system where business owns govern
The proper definition is slightly different, and is what most other bodies recognize (specifically those certifying records for sailors). The trip must cross over 2 points on the globe that are diametrically opposed, and it must cross every meridian (longitude line). It must end at or beyond the point of departure, so in the case of an aircraft, it's normal to overfly the departing airport prior to landing, just to void any possibility of someone showing that you landed on the runway at a point prior to the point of liftoff, so you didn't really go 'all the way around'.
To be technically correct, your quick circle of the north pole will qualify, if the same flight includes a pass over the south pole, and lands back at, or beyond the point of departure.
For the purposes of this trip, FAI has bastardized the rules, but, i suspect they actually do have diametrically points on the globe in the flight plan, so that the record can be recognized by other sanctioning bodies.
Extra fuel is not a problem for landing - you just dump it overboard at 10,000 feet before you descend to land. This is standard operating procedure on the boeing 747 - it isn't certified to land at a full fuel+passenger/cargo load (landing gear will collapse) so once it takes off it has to get rid of fuel before it lands again one way or another. So if some dude has a heart attack right after takeoff, they will climb the airplane up and dump the fuel before landing again (they have to be at a certain height to ensure that all the fuel evaporates on its way down and distributes evenly far from populated areas).
Why does everyone assume that *testing* the tank mean that it has to be flown?
1) fill with liquid (fuel, water, beer), look for puddles under tank (in case of beer, call party afterwards)
2) fill with pressurised gas (air, not *fuel*) monitor pressure
3) Test at alititude? fill with fuel and put in vacuum chamber (granted a *very* big one)
There are lots of ways of testing a system without needing to fly around in a circle for 3 days or drop 9 tons of fuel on some unsuspecting farmer.
Considering my education and that I have worked for a couple of aerospace companies and for NASA/JPL, and that I have been a licensed pilot for two thirds of my life, I'd say that I, random Joe Slashdot Reader know a good bit about the subject.
OTOH, indeed he does know what he's doing, he's building radical craft and flying them. What most readers don't seem to realize is that anomalous behavior does not imply a CRASH!
Good judgement comes from experience, and experience comes from bad judgement.
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