Boom supersonic jet readies for rollout • Hacker News Board

Re: Boom supersonic jet readies for rollout

#51

Post by pedalpete » Fri, Jul 10, 2020, 12:52 AM UTC

galacticaactual wrote: post #23

As a (pre-Covid) extreme frequent flyer, supersonic and other rapid point to point initiatives are thoroughly unenticing. Part of the reason I loved long flights was the ability to put away the laptop and zone out to a book or movie with some wine before landing, dealing with immigration, hotels, Ubers, and days of frenetic, high stress meetings afterward. The prospect of trying to optimize how fast we can jump from…

You're not doing Sydney->Los Angeles, Santiago->Tokyo type long-haul, are you. When you're continent jumping (excluding Eastern US to Europe) 7hrs at supersonic is long enough to get a movie and relax a bit. When you're getting 16 hour flights on a regular basis, you get used to it, but when you've seen all the movies, you realize how much time you've wasted on a plane.

Re: Boom supersonic jet readies for rollout

#52

Post by mauvehaus » Fri, Jul 10, 2020, 12:56 AM UTC

ceejayoz wrote: post #47

orbital-decay wrote: post #17

Earlier quoted context omitted.

"Privately built", so it's technically accurate, even if there's still an elephant in the room. Similar to that amusing SpaceX marketing speak with the Falcon Heavy being "the most powerful orbital rocket since Saturn V", which was also technically true because both Energia flights were payload-assisted. (they changed that line since then)

That's not the issue. It's the third supersonic airliner, not the second; the Soviet Union had the Tu-144.

I think anybody would be hard-pressed to argue that the Tu-144 saw meaningful commercial passenger service. Neither has Boom yet, to be fair, but it at least isn’t provably a failure at this point.

Re: Boom supersonic jet readies for rollout

#53

Post by graycat » Fri, Jul 10, 2020, 12:56 AM UTC

Their engines are a version of the General Electric J85 that dates from the 1950s. It's been very widely used in both military and commercial aircraft. One version was used in the Dassault DA-20 executive aircraft used at the start of FedEx after FedEx cargo door, etc. modifications.

Re: Boom supersonic jet readies for rollout

#54

Post by redis_mlc » Fri, Jul 10, 2020, 12:57 AM UTC

abeppu wrote: post #33

Can anyone here comment on the kinds of things you can and can't learn accurately from a scaled prototype? I'd guess that for something that flies, changing the surface area/volume ratio makes a big difference.

I study aerodynamics, and haven't heard of problems from scaling down the models.

The main problem with supersonic wind tunnels is ensuring there's no interference from shock waves bouncing off the sides of the tunnel, which is why the X-plane program used actual airplanes. So wind tunnels are rated to a certain Mach, and above that, like for hypersonic, actual airplanes are still used.

FYI: I believe the DC-3 was the first passenger airplane designed with a wind tunnel, and as a result was efficient enough to be the first twin-engine commercial passenger airplane to fly over the Rockies with a safety margin to fly single-engine, and adequate to be the first proposed Shuttle wing design.

Re: Boom supersonic jet readies for rollout

#55

Post by chemeng » Fri, Jul 10, 2020, 12:58 AM UTC

kgermino wrote: post #46

Alupis wrote: post #38

Earlier quoted context omitted.

NOE flying is designed to come in fast and low, to avoid radar coverage. Announcing you're coming, and your heading, by breaking everyone's windows for miles around is quite noticeable.

(Big fat disclaimer: I don’t understand anything I’m about to say) Wouldn’t the windows be broken _behind_ the plane? In my mental model, you’re flying below radar so anyone on the ground will know you’re there anyway. If you’re sub-sonic people hear/see the plane and you hope they don’t have time to do anything before you strike. If you’re supersonic they hear/see the plane, their windows break, and you hope they do…

You would leave a long trail of broken windows and reports from the moment you went supersonic in their territory, charting your trajectory. Threat detection is a network, not a single point.

However, if you're moving fast enough and the target is close enough, your premise is valid. They would not have time to react. Cruise missiles tend to be used for those mission profiles.

Re: Boom supersonic jet readies for rollout

#56

Post by taneq » Fri, Jul 10, 2020, 1:00 AM UTC

nscalf wrote: post #40

galacticaactual wrote: post #23

As a (pre-Covid) extreme frequent flyer, supersonic and other rapid point to point initiatives are thoroughly unenticing. Part of the reason I loved long flights was the ability to put away the laptop and zone out to a book or movie with some wine before landing, dealing with immigration, hotels, Ubers, and days of frenetic, high stress meetings afterward. The prospect of trying to optimize how fast we can jump from…

This sounds like you need a career change. People who want to get where they are going will absolutely welcome a faster plane.

But what if you just enjoy flying? I still get a thrill out of it even in cattle class. (Getting up at 3am to make the 5am flights they put us on is a whole different matter, though...)

Edit: These are 1.5-2hr intrastate flights, though. If I were going nonstop to London every week I would be all there for the supersonic. Actually who am I kidding, I wanna fly supersonic just for its own sake.

Re: Boom supersonic jet readies for rollout

#57

Post by starpilot » Fri, Jul 10, 2020, 1:01 AM UTC

abeppu wrote: post #33

Can anyone here comment on the kinds of things you can and can't learn accurately from a scaled prototype? I'd guess that for something that flies, changing the surface area/volume ratio makes a big difference.

https://i2.cdn.turner.com/money/dam/assets/170324152006-boom...

This is a tech demonstrator and not quite a "scaled prototype." Two occupants vs ~40 makes it pretty much a completely different aircraft. What it's probably demonstrating is some key design aspects like inlet/engine interactions, sonic boom mitigation, thermal resistance on various points, and overall validating simulation data. It won't show anything about extrinsic performance like range or takeoff distance of the final passenger jet, at least not directly.

Re: Boom supersonic jet readies for rollout

#58

Post by Alupis » Fri, Jul 10, 2020, 1:06 AM UTC

starpilot wrote: post #48

Alupis wrote: post #35

Earlier quoted context omitted.

I trust Boom has smart people working on these things, but... model aviation doesn't scale up[1]. It's interesting they're going with a scaled-down model instead of a full-scale testbed. The article seems to incidate they're wanting to go from the scaled-down model as a PoC, then onto an actual airline that JAL want's to fly. I'd think they'd need a full-sized PoC first... > “They want to enjoy a first-mover advantag…

Quadcopters don't scale up. Flyable scale models have used extensively in other aviation research: https://www.youtube.com/watch?v=pgDRkNseNxU

There's nothing special about a quadcopter.

An airfoil is an airfoil.

Re: Boom supersonic jet readies for rollout

#59

Post by tedunangst » Fri, Jul 10, 2020, 1:06 AM UTC

taneq wrote: post #56

nscalf wrote: post #40

Earlier quoted context omitted.

This sounds like you need a career change. People who want to get where they are going will absolutely welcome a faster plane.

But what if you just enjoy flying? I still get a thrill out of it even in cattle class. (Getting up at 3am to make the 5am flights they put us on is a whole different matter, though...) Edit: These are 1.5-2hr intrastate flights, though. If I were going nonstop to London every week I would be all there for the supersonic. Actually who am I kidding, I wanna fly supersonic just for its own sake.

I'm sure there will still be some slow flights for the people who just like flying for the movies.

Re: Boom supersonic jet readies for rollout

#60

Post by orbital-decay » Fri, Jul 10, 2020, 1:08 AM UTC

ceejayoz wrote: post #47

orbital-decay wrote: post #17

Earlier quoted context omitted.

"Privately built", so it's technically accurate, even if there's still an elephant in the room. Similar to that amusing SpaceX marketing speak with the Falcon Heavy being "the most powerful orbital rocket since Saturn V", which was also technically true because both Energia flights were payload-assisted. (they changed that line since then)

That's not the issue. It's the third supersonic airliner, not the second; the Soviet Union had the Tu-144.

Which is what I meant - it was designed and built by the state, not a private company, so the careful wording is probably correct.

Although come to think of it, Sud Aviation/Aerospatiale was also a state-owned company, and the BAC wasn't private either, so the nitpicking can go on forever.