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Boom (YC W16) – Supersonic Passenger Airplanes

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Re: Boom (YC W16) – Supersonic Passenger Airplanes

#471

Post by bertil »

sounds wrote: post #265
bertil wrote: post #250

Earlier quoted context omitted.

Would it make sense for you to fly West from SFO, turn around, go super-sonic over the ocean and fly towards NY — then again, decelerate over the Atlantic, and turn back? i.e. what is the distance from the shore you can boom?

Everywhere the plane is supersonic, it emits the boom. Your question implies that the only boom is when you "go super-sonic." http://physics.stackexchange.com/questions/68354/is-a-sonic-... Would a Mach 1 plane hear a boom if overtaken by a Mach 3 plane? http://aviation.stackexchange.com/questions/17243/does-a-mac... I understand why you got downvoted, but I don't think the question was actually repellant. If it were…

Didn’t get down-voted overall so fine on that end.

I actually never though of the existence of a continuous cone of focus outside of the plane — the graph I had seen were all focused on the whether the plane heard it.

I guess an alternative option would be to find routes above the polar circle, or through the narrow of Central america — but the increased distance would make it less interesting at “just” Mach 2.2.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#472

Post by jessaustin »

ant6n wrote: post #466
azernik wrote: post #279

Earlier quoted context omitted.

Lots of hotels that cater to business customers already to this - go to the local Hilton and pay $XYZ to use their telepresence room for an hour.

But can I buy the guy on the other end a beer?

Sure, unless the hotel at his end is in a "dry" location.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#473

Post by jessaustin »

neurotech1 wrote: post #292
jandrese wrote: post #252

Earlier quoted context omitted.

A brand new advanced composite supersonic jet flying in a year's time? Color me skeptical. There are literally millions of things that need to be designed for this, and many of them will be bleeding edge. And this is from some tiny startup? A line like that sets off some big flashing red lights for me. Either they're incompetent and have grossly underestimated the amount of work needed to complete this, or it's a sca…

Lockheed Skunkworks have actually built prototype jets in under 2 years from go ahead to first flight. The A-12 (predecessor to the SR-71) went from contract to first flight in just over 2 years. Didn't Burt Rutan make a composite aircraft from design to first flight in a year back in the 80s? Getting the aircraft certified and into production is where most of the actual expense is.

A company like this that manages to produce a supersonic flying scale model will probably have access to the capital required for those later steps.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#474

Post by jessaustin »

esaym wrote: post #180
flavio87 wrote: post #112

This sounds awesome. However I'm a bit saddened that there is no mention of CO2 or climate change in this discussion. What about building solar planes vs just faster planes will do even more harm to the environment if people start flying more because time is now shorter?

Just think how much C02 you'd produce if you took a ship across the ocean for days on end....

Like, a sailing ship?

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#475

Post by jasonwatkinspdx »

designtofly wrote: post #453
jasonwatkinspdx wrote: post #353

Earlier quoted context omitted.

> but no amount of tweaking is going to make a turbofan work at supersonic speeds Sure they can. It's the inlet's job to slow the flow to subsonic. Turbofans have been used on supersonic military aircraft since the 1960's. Go read about intake ramps. Then learn about diverterless supersonic intakes. You're yelling scam pretty loud for someone that clearly doesn't know basics of the topic area. Edit: My guess is the e…

But those intakes don't work for free. You will encounter huge losses and drag penalties. And military jets aren't designed to fly 3500 miles supersonically the entire way. The vast majority of miltiary jets have a maximum supersonic time that can be measured in minutes.

This isn't quite so cut and dried: the ram effect can help or hurt depending on the exact context and numbers.

There are several 4th generation fighters with sustained supersonic cruise, as well as older aircraft like the B1. The basic technology has been around for decades. Nothing about the proposed supersonic small commuter jet is impossible from an engineering perspective, though aspects of it won't be _easy_, and it is entirely possible the business case doesn't work out.

I mostly replied above because of the categorical statement that supersonic flight with turbofans is impossible. The reality is that virtually all supersonic aircraft use engines with some bypass. The Concorde's engines oddly enough are one of the few zero bypass designs used in industry.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#476

Post by tempestn »

mark-r wrote: post #402
tempestn wrote: post #278

Earlier quoted context omitted.

As others have said, the boom is continuous. However, what you could (and presumably would) do is gain altitude at sub-sonic speed, then go supersonic only once cruising altitude is reached. That should help with volume. Also presumably they would avoid flying over major population centers.

Is the boom attenuated by flying through much less dense air?

Possibly! Certainly if the plane was traveling in a vacuum it would produce no boom, so one would assume that the boom would be reduced as the air became less dense. However my understanding is that most of the advantage from altitude comes from the attenuation (or really spreading out) of sound with the square of distance.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#477

Post by mark-r »

tempestn wrote: post #476
mark-r wrote: post #402

Earlier quoted context omitted.

Is the boom attenuated by flying through much less dense air?

Possibly! Certainly if the plane was traveling in a vacuum it would produce no boom, so one would assume that the boom would be reduced as the air became less dense. However my understanding is that most of the advantage from altitude comes from the attenuation (or really spreading out) of sound with the square of distance.

Since hearing response is logarithmic, the inverse square law probably isn't as helpful as you'd expect.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#478

Post by rwmj »

jessaustin wrote: post #469
rwmj wrote: post #436

Earlier quoted context omitted.

Why do you bother having pilots on board? Why not have the majority of the flight directed automatically, perhaps assisted by a ground manager dealing with several planes at once?

Savvy passengers might value someone with "skin in the game".

I think you may mean "naive passengers will be reassured by two men in suits". Savvy passengers would know how pilot error is the main cause of crashes.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#479

Post by jessaustin »

rwmj wrote: post #478
jessaustin wrote: post #469

Earlier quoted context omitted.

Savvy passengers might value someone with "skin in the game".

I think you may mean "naive passengers will be reassured by two men in suits". Savvy passengers would know how pilot error is the main cause of crashes.

That will be a fair statement once there are any commercial (or general aviation!) passenger flights for which all flight operations take place without human intervention. We don't live in that world yet. Saddling an already risky endeavor with the additional risk of having to invent a completely new class of control software is really too much to ask.

If you think this will be easy, why not just start by outfitting e.g. simple four-passenger Cessnas with your amazing new software that obviates pilots? There's got to be a market there, for something that works. Then when you've got that handled, move up to bigger and faster planes.

Re: Boom (YC W16) – Supersonic Passenger Airplanes

#480

Post by zeckalpha »

bvi wrote: post #304
bscholl wrote: post #192

Hi - I'm Blake, Founder/CEO at Boom. After watching no tangible progress in supersonics since Concorde was shut down, I started Boom because I want supersonic flight in our lifetime. Not just as a private jet, but something most anyone can afford to fly. Will try to answer as many questions here as I can.

Honest / naive question. How do you even start an aerospace company "in your basement"?

It's been done: https://en.wikipedia.org/wiki/Burt_Rutan
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