3 ms·
"The SR-71 was of course made of Titanium and dealt with (2) by taking off with as little fuel as possible and then refueling once it was up in the air -- an an
by rsync 4y ago
"The SR-71 was of course made of Titanium and dealt with (2) by taking off with as little fuel as possible and then refueling once it was up in the air -- an answer which isn't suitable for civilian use."
Couldn't we, in theory, slingshot the planes into the air to achieve the same relative fuel burn rates ?
I think this only exists on aircraft carriers ?
- rlpb 4y ago> Couldn't we, in theory, slingshot the planes into the air to achieve the same relative fuel burn rates ? The required release velocity would need to be so high that drag from air resistance (which increases with the square of velocity) would slow down the vehicle such that there would be no benefit. See: https://en.wikipedia.org/wiki/Max_q https://en.wikipedia.org/wiki/Max_q
- rsync 4y agoThank you - that's interesting. However, it then raises the question: What are they doing on aircraft carriers and how is that different ? https://en.wikipedia.org/wiki/Aircraft_catapult https://en.wikipedia.org/wiki/Aircraft_catapult ... I assumed those had some fuel-use benefit, but perhaps their only benefit is shortening the runway ?
- V_Terranova_Jr 4y agoCarrier catapults violently accelerate aircraft to the point they are going fast enough to lift their own weight, within the takeoff length on the deck. You could likely lessen fuel burn of a supersonic aircraft taking off (as you could with a subsonic aircraft) by accelerating it via a catapult of sorts, but you have to do so at acceleration levels tolerable to all passengers, which would make for a long, unwieldy catapult. Release speed is also obviously going to be very subsonic.
- rlpb 4y agoThe fuel needed to get to take-off speed is a tiny fraction of the fuel needed to get from take-off to altitude. In practice, the benefit is for runway length only.