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Boom supersonic jet readies for rollout

airlineratings.com

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Re: Boom supersonic jet readies for rollout

#181

Post by kolinko »

gorgoiler wrote: post #178

Is there an intuitive everyday explanation as to why the sound barrier is so hard to break? I know that the forces in an airframe change a lot as you go faster, and that the controls invert for some reason, but I’ve never really had a good feel as to why. Perhaps something related to swimming?

Hm, imagine your ship made really big waves when swimming. Below the speed of waves you don’t really need to worry about them because you don’t really experience them - they just run ahead of you.

If your speed is close to the speed of waves, the waves that you produce get stuck on top of one another, so you have this huge wave ahead of you.

If you want to break through that barrier, you need a really strong ship to plow through that huge wave, but once you’re through it, it gets smoother - you don’t encounter your own waves any more.

But now the problem is: the moment you slow down, or make a turn, all the waves you produced will hit you from the back.

We don’t get that with water due to various reasons, but we get that with air and sound.

Re: Boom supersonic jet readies for rollout

#182

Post by ivalm »

iso947 wrote: post #176
catalogia wrote: post #123

Earlier quoted context omitted.

> (very very close). Eh, within 15 miles or so. 4MPH * 24h = 96 mile circumference circle, 96 miles / 2pi ~= 15 miles.

You are going to struggle to walk at 4mph in Antarctica

That’s why we need global warming!

Re: Boom supersonic jet readies for rollout

#183

Post by kolinko »

TylerE wrote: post #101
JKCalhoun wrote: post #68

Earlier quoted context omitted.

Yeah, much more excited if there were talk of high-speed rail criss-crossing the U.S.

High-speed rail isn't high speed enough. Even with way faster than current tech and NO stops you'd still be looking at taking 12+ hours for what a plane can do in 5. That's ignoring the trillions it would cost. The US does not have the population density to make HSR viable.

12 hours is a lot, but for shorter distances most people would prefer a good train to a plane. Living in Europe, I will take 4-5 hour train ride compared to a 1h flight, most of my friends as well. Many people will also prefer 5-8 hour 100mph train ride to 1h plane ride due to comfort, price and carbon footprint.

Re: Boom supersonic jet readies for rollout

#184

Post by philjohn »

masklinn wrote: post #165
alfalfasprout wrote: post #118

Earlier quoted context omitted.

The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient. Great for a fighter jet where you need a sudden burst of extreme thrust, but not something you want a long-haul airliner to use. Boom uses turbofan engines to reach supersonic speeds which are much, much more efficient. In fact, many airliners could theoretic…

> The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient. Concorde didn't use afterburners "at speed". The afterburners were used for takeoff, and to go through the mach wall. Concorde burned insane amounts of fuel on the ground because turbojets are very inefficient at low-speed. Not unlike the SR-71's really (th…

Didn't SR-71's also leak fuel when on the ground?

Re: Boom supersonic jet readies for rollout

#185

Post by notahacker »

phire wrote: post #139
flyGuyOnTheSly wrote: post #115

Earlier quoted context omitted.

The concorde didn't fail because it was expensive. It ran profitably for 27 years. [0] It failed because it crashed and killed 109 people 3 years before they threw in the towel. [1] [0] https://en.wikipedia.org/wiki/Concorde#Operating_economics [1] https://en.wikipedia.org/wiki/Air_France_Flight_4590

The main reason the airlines managed to run Concorde at a profit is because they bought the planes for quite cheap. At one point the British government even sold two planes to British airways for £1 each. [0] The airlines might have profited, but the R&D and manufacturing programs were a more or less write offs. [1] https://simpleflying.com/british-airways-1-pound-concorde/

It also ran on only two routes for most of that time, with all others shut down because airlines lost money operating Concorde on them even without having to pay off the capital costs.

Re: Boom supersonic jet readies for rollout

#186

Post by jlg23 »

kolinko wrote: post #183
TylerE wrote: post #101

Earlier quoted context omitted.

High-speed rail isn't high speed enough. Even with way faster than current tech and NO stops you'd still be looking at taking 12+ hours for what a plane can do in 5. That's ignoring the trillions it would cost. The US does not have the population density to make HSR viable.

12 hours is a lot, but for shorter distances most people would prefer a good train to a plane. Living in Europe, I will take 4-5 hour train ride compared to a 1h flight, most of my friends as well. Many people will also prefer 5-8 hour 100mph train ride to 1h plane ride due to comfort, price and carbon footprint.

Well... price-wise, in lots of Europe, taking a plane is cheaper..

What really made the difference for me is that the 4-5 hour train ride is done after 4 to 5 hours. My 1 hour flight starts 3 to 3.5h before the flight to get to the airport and through security and at the destination, after de-boarding, I'll spend another hour for security and to get from the airport to my actual destination.

Re: Boom supersonic jet readies for rollout

#187

Post by dotancohen »

> Boom’s first major airline partner in the development of the > first privately built supersonic airliner and the second ever > after Concorde, retired in 2003, is Japan Airlines with an > option for 20 aircraft.

How could any reporter, especially one writing for a publication called "airlineratings", not research the topic at hand? It is widely known in the aviation community that the Soviet union flew the supersonic TU-144 even before the Concorde flew.

Re: Boom supersonic jet readies for rollout

#188

Post by dotancohen »

paulmd wrote: post #154
alfalfasprout wrote: post #118

Earlier quoted context omitted.

The reason for that is that the concorde used afterburners (basically, pump fuel into the high speed exhaust for extra thrust) which are incredibly inefficient. Great for a fighter jet where you need a sudden burst of extreme thrust, but not something you want a long-haul airliner to use. Boom uses turbofan engines to reach supersonic speeds which are much, much more efficient. In fact, many airliners could theoretic…

Concorde itself could have been much more efficient, there were plans for a "Concorde B" with high-bypass engines that would have carried a larger payload with additional range at higher efficiency. https://www.heritageconcorde.com/concorde-b

Warning: That page contains a background animation that cannot be disabled, even when disabling page styles. I had to open it in W3M, which I'm glad I did as it was very informative.

Re: Boom supersonic jet readies for rollout

#190

Post by [deleted] »

agurk wrote: post #171
DomenicoMazza wrote: post #18

If I recall correctly the Concorde used about 2 tonnes of fuel rolling on the ground alone.. I wonder how this new aircraft fares for fuel consumption? I believe the Concorde is a marvel. You could travel faster than the rotation of the earth in it! However I don’t think we need more environmentally unsustainable travel.

Looking at the Concorde's fuel usage taxing is only part of the picture. All turbine engines are very inefficient at low power outputs due to the need to use energy to create sufficient compression for them to function. On top of this the Olympus engines generated a lot of thrust at idle, so much so that only two were used for taxing and it was still apparently tricky to control. While cruising at supersonic speeds t…

[deleted]
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