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how much fuel would the other plane use
getting the supersonic in the air? |
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Not sure, but the range would definitely be greater. |
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It might also be able use smaller engines - if launched from altitude. It shouldn't need so many compressors and stators as it could nose dive to high speed and benefit from ram air compression in a kind of aerospace anaolgy to bump starting a car. |
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This would reduce engine weight and parasitic losses in the engine. |
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What would the max terminal velocity be - maybe it would be high enough to just use a ramjet. If not how many compressor stages could you lose if you started the engine at 400-500 miles an hour? |
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If the carrier plane was long enough, and the passengers were in comfortable enough seats, you could catapult the SST along the TOP of the carrier at high acceleration, to achieve ramjet speeds. |
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I don't think you've any chance of achieving ramjet speeds falling through air. |
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//The wings on concorde need to be very large to allow it to take off// And also, presumably, to land. [-] |
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[coprocephalous] That was covered: when it's landing, it's much lighter, because it's not loaded up with fuel. A large proportion of any aeroplane's take-off weight is fuel; this is especially true of SSTs. |
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Use a low altitude, high-lift vehicle to launch a higher altitude lower lift vehicle to launch a higher altitude lower lift vehicle to launch a ... |
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G.K.Chesterton? 8~) Ah, no, Jonathan Swift. |
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// when it's landing, it's much lighter,
because it's not loaded up with fuel // |
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a) Don't all transatlantic flights anyway
have to carry enough surplus fuel to get
half way back or something? |
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b) I would imagine that Concorde's wing
area is _already_ determined by its
landing speed and weight, allowing for
the expected residual fuel load. |
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Sadly irrelevant anyway, now that
humankind has regressed to the point
where, not only can we not put a man
on the moon any more, we can't even
carry him with his luggage at Mach2. |
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I thought the reason the concorde had
problems was that no American state
(US being world centre of wealthy air
travel) would permit sonic booms over
their territory.
If it was a problem of take off weight
why not take off inefficiently with a tiny
fuel load (say 5%) then climb to a nice
height and do in air refuelling (Military
refuel fighters mid air all the time). |
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Still I like this - if the plane could fly
very very high then this might be a cool
way of getting the wing right. |
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Allegedly, the real problem in the early
days boiled down to protectionism
(though that may be an Anglo-biased
viewpoint). There were protests based
on the noise, but these were probably
spurious and secondary to the main
motivation. The sonic boom wouldn't
really have been an issue, at least for
east-coast destinations, since Concorde
would have gone sub-sonic over land.
(As far as I know, this is what it did on
the London-NY route anyway). |
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The real objection to SSTs is fuel consumption (and correspondingly carbon dioxide production). |
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[MaxBuchanan] Is there some reason why you need bigger wings to land than to take off, for a given weight? |
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//The real objection to SSTs is fuel
consumption// True, perhaps, but
bollocks to that - Concorde was the
most beautiful thing in the air. |
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//Is there some reason why you need
bigger wings to land than to take off,
for a given weight// I'm not sure (I
often talk out of my arse), but I think
the point is that, on take-off, you can
just wham up the power and get up to
the necessary speed, using most of the
runway in the process. On landing,
there's a limit to how fast you can safely
decelerate, and you can't guarantee that
the pilot will hit the numbers and have
the full length of the runway to slow
down in. |
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Ah, maybe. I don't think Concorde had reverse thrust on the engines - but as long as the runway's dry, brakes can decelerate you pretty fiercely if needs be. |
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Interesting comment about landing accelerations compared to take-off. |
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I've just added a link to another possible use for this type of craft. Fast package delivery. I think most of the links refered to, deal with hypersonic flight and suborbital flight. But even if you only triple the speed of the airmail segment of a delivery you get a whopping 67% reduction in travel time. Going faster than this brings successively less and less benefit. So maybe there is a place for a 'more sedate' supersonic link in a global delivery network. |
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//I don't think Concorde had reverse
thrust on the engines// It did - there
were sort of air scoops which could
rotate to deflect the jet output forward. |
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I may be wrong about all this, but I
think the general idea is that you need
to be able to land in a shorter distance
than you take off in, without relying too
heavily on reverse thrust or brakes. |
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Also, it's probably best to land as slowly
as possible - you are making the
transition from air (soft) to ground
(hard), which is less forgiving than the
transition from ground (hard) to air
(soft). |
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It's also important to land close to the
ground. |
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