3 ms·

Lift to drag is interesting - but without dividing by seats or tons is incomplete. You’re not really measuring work being done (actually transporting goods or

Lift to drag is interesting - but without dividing by seats or tons is incomplete. You’re not really measuring work being done (actually transporting goods or people). These problems are hard. Lift induced drag goes down as velocity decreases, parasitic drag goes up as velocity increases. There’s there’s wave drag to contend with. Yes there’s weird places where going faster is helpful, but I doubt we’re going to see real net efficiency gains going faster than Mach .8-9 anytime soon.

credit_guy 4y ago
Glad we got to this point. So, can Boom compete with subsonic airplanes. Where can they have an edge? They have two actually: 1. they are a startup. Boeing and Airbus are old and ossified. Smaller manufacturers are probably not as ossified, but they already have a niche, so their risk appetite is different: they prefer to put their research money to work towards incrementally improving their current designs. Boom is in a life and death situation, they have a huge fire under their feet, and so they'll get more research done for the same amount of dollars 2. Clean slate. All current civilian airplanes are cylinders with flat wings. It's a proven formula. Manufacturers don't want to move too much from a proven formula. But Boom does not have this type of fetters. In particular, they can design a body that follow the Whitcomb area rule [1]. Which is what they are actually doing [2]: Contoured fuselage: According to the principle of area-ruling, Overture’s fuselage has a larger diameter toward the front of the aircraft and a smaller diameter toward the rear. Boom has applied this design technique to minimize drag and maximize fuel efficiency at supersonic speeds. In addition to that, Boom plans to use wings that are not flat (they call them gullwings). Presumably, they know what they are doing, they say they used 26 million-core hours of compute between the first and the second iteration of their Ouverture. Will the manufacturing costs explode? I guess they should be higher than for traditional geometries. But that works to their advantage: it keeps the current manufacturers from trying these non-standard geometries, and keeps them in a local optimum from which they find it harder to move. But it won't be a dealbreaker for a premium aircraft. That's basically the Tesla Roadster gameplan. [1] https://en.wikipedia.org/wiki/Area_rule https://en.wikipedia.org/wiki/Area_rule [2] https://boomsupersonic.com/news/post/boom-supersonic-reveals-refined-overture-and-announces-landmark-market-expanding-alliance-with-northrop-grumman-and-new-tier-one-suppliers https://boomsupersonic.com/news/post/boom-supersonic-reveals...

credit_guy 4y ago

Glad we got to this point. So, can Boom compete with subsonic airplanes. Where can they have an edge? They have two actually: 1. they are a startup. Boeing and Airbus are old and ossified. Smaller manufacturers are probably not as ossified, but they already have a niche, so their risk appetite is different: they prefer to put their research money to work towards incrementally improving their current designs. Boom is in a life and death situation, they have a huge fire under their feet, and so they'll get more research done for the same amount of dollars 2. Clean slate. All current civilian airplanes are cylinders with flat wings. It's a proven formula. Manufacturers don't want to move too much from a proven formula. But Boom does not have this type of fetters. In particular, they can design a body that follow the Whitcomb area rule [1]. Which is what they are actually doing [2]: Contoured fuselage: According to the principle of area-ruling, Overture’s fuselage has a larger diameter toward the front of the aircraft and a smaller diameter toward the rear. Boom has applied this design technique to minimize drag and maximize fuel efficiency at supersonic speeds. In addition to that, Boom plans to use wings that are not flat (they call them gullwings). Presumably, they know what they are doing, they say they used 26 million-core hours of compute between the first and the second iteration of their Ouverture. Will the manufacturing costs explode? I guess they should be higher than for traditional geometries. But that works to their advantage: it keeps the current manufacturers from trying these non-standard geometries, and keeps them in a local optimum from which they find it harder to move. But it won't be a dealbreaker for a premium aircraft. That's basically the Tesla Roadster gameplan. [1] https://en.wikipedia.org/wiki/Area_rule https://en.wikipedia.org/wiki/Area_rule [2] https://boomsupersonic.com/news/post/boom-supersonic-reveals-refined-overture-and-announces-landmark-market-expanding-alliance-with-northrop-grumman-and-new-tier-one-suppliers https://boomsupersonic.com/news/post/boom-supersonic-reveals...