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American Airlines agrees to purchase Boom Supersonic Overture aircraft

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Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#261

Post by jefftk »

chx wrote: post #201
Justin_K wrote: post #162

Earlier quoted context omitted.

You are arguing with a straw man. Nobody said driving to the airport will change. The claim is for the price of business class, get there in half the time.

What I am saying is that you can only save so much on the flight time over such a short range when the overall trip has fixed time segments. If we were looking at shaving off seven hours of a 20-21 hour London-Sydney trip then yeah, that's massive even if the flight itself is merely 19 hours of that.

In other words, running into Amdahl's Law [1]

[1] https://en.wikipedia.org/wiki/Amdahl%27s_law

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#262

Post by mmaunder »

Burning more Jet-A to get less people around the world faster has got to be the most tone deaf idea this decade. I'm a pilot, I just attended Airventure, and I love the history around SR-71, Concorde and the other incredible high speed planes we've built. But this is an idea that had its time and aviation has moved on to high bypass turbofan engines, reliability, safety, fuel efficiency and reducing our environmental impact.

There is so much opportunity for innovation in areas of aviation where we desperately need to innovate: Getting rid leaded avgas, moving away from fossil fuels altogether which includes fields like energy storage and electric propulsion, developing an efficient trainer to replace the piston lead-gasoline burning C172 that is so ubiquitous and makes up much of the 1500 required hours for an ATP license. So many opportunities.

Aviation is ripe for innovation. This ain't it.

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#263

Post by danans »

tgv wrote: post #182
phire wrote: post #116

Earlier quoted context omitted.

Are you saying that sustainable synthetic fuels can't exist? Or don't current exist? Because those are two very different statements.

Well, it requires a lot of power, so building a large plant will be difficult and expensive.

> building a large plant will be difficult and expensive.

Utility scale renewables are in pennies pwr kWh in Levelized Cost, and continually dropping.

There are 10kWh/liter of jet fuel. Utility scale solar is 3c/kWh LCOE today.

Assuming a pessimistic 10% efficiency in electricity to synthetic jet fuel conversion via H2 hydrolysis and the Fischer Tropsch process, that's a hypothetical $3/liter of synthetic jet fuel.

Current petroleum based jet fuel is $1.50/liter.

If you improve the conversion efficiency to 20% and lower the LCOE of utility scale solar to 1c/kWh (projected by 2050), and the hypothetical liter of synthetic jet fuel drops to 50c/liter, all while petroleum jet-fuel grows increasingly scarce and more expensive.

The efficiency of synfuel production could rise significantly as the efficiency of feedstocks like H2 hydrolysis (already 50%+) increase, and if if CO for Fischer Tropsch can be sourced from biomass instead of sourcing it from atmospheric CO2.

Finally, it's likely that in the future we'll switch to using hydrogen directly as an aviation fuel, bypassing hydrocarbons altogether, at which point the electricity to air conversion efficiency nears 80%.

At those prices, you can begin to afford to overbuild renewable capacity to drive a synfuel pipeline to store that energy chemically, which we will arguably need to do for seasonal energy storage anyways.

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#264

Post by cannaceo »

ISL wrote: post #24
akmarinov wrote: post #16

Earlier quoted context omitted.

Not only very expensive, but basically coach class all the way through, even for the rich people.

Rich people value time highly. Coach-class that gets you somewhere quickly can be worth a lot more than first-class that takes twice as long.

As someone who flies first class there is no way I'm flying coach to save time. Flying business is about the lounges, the meals, the service, and the ability to stretch out your legs.

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#266

Post by FredPret »

mshook wrote: post #193
ISL wrote: post #24

Earlier quoted context omitted.

Rich people value time highly. Coach-class that gets you somewhere quickly can be worth a lot more than first-class that takes twice as long.

Still, flying westbound fast makes tons of sense as you can arrive "before" you took off (local time) and thus you get a whole day in front of you. But eastbound makes a lot less sense, unless you're just trying to save time. Because flying at night eastbound won't make you gain much compared to a regular red eye and flying during the day, you'll land at night...

It always makes a lot of sense - time saved is time saved.

Flying east fast after a day of meetings means you get in bed on time.

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#267

Post by JohnJamesRambo »

jackmott42 wrote: post #93
JohnJamesRambo wrote: post #36

Earlier quoted context omitted.

Can someone do the math on how much sustainable energy we would be wasting so people could get somewhere faster than a normal plane?

Wind resistance is supra linear naturally, but its also a more aerodynamic plane than a normal one, but also carries less passengers. Its prolly something like 5x-10x worse.

Good Lord.

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#268

Post by adolph »

cjbgkagh wrote: post #108
replygirl wrote: post #88

Earlier quoted context omitted.

why the downvotes? the original design was trying to use 3x turboprops, and i can see articles on google about them switching to 4x turbofans after the xb-1 work edit: see parent edit, i was wrong. you guys are pretty good at making someone with misinfo feel bad though

You have to be mixed up; a turboprop has a propeller attached to the jet engine. No-one in their right mind would use a turboprop supersonically. It would make an insane amount of noise.

Define “right mind”

The Republic XF-84H "Thunderscreech" was an American experimental turboprop aircraft derived from the F-84F Thunderstreak. Powered by a turbine engine that was mated to a supersonic propeller, the XF-84H had the potential of setting the unofficial air speed record for propeller-driven aircraft, but was unable to overcome aerodynamic deficiencies and engine reliability problems, resulting in the program's cancellation.

[. . .]

Unlike standard propellers that turn at subsonic speeds, the outer 24–30 inches (61–76 cm) of the blades on the XF-84H's propeller traveled faster than the speed of sound even at idle thrust, producing a continuous visible sonic boom that radiated laterally from the propellers for hundreds of yards. The shock wave was actually powerful enough to knock a man down; an unfortunate crew chief who was inside a nearby C-47 was severely incapacitated during a 30-minute ground run. Coupled with the already considerable noise from the subsonic aspect of the propeller and the T40's dual turbine sections, the aircraft was notorious for inducing severe nausea and headaches among ground crews. In one report, a Republic engineer suffered a seizure after close range exposure to the shock waves emanating from a powered-up XF-84H.

The XF-84H design top speed was Mach .9 and probably made it to .7 in testing.

https://en.m.wikipedia.org/wiki/Republic_XF-84H_Thunderscree...

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#269

Post by Rackedup »

metadat wrote: post #244
Rackedup wrote: post #240

Earlier quoted context omitted.

> When reading the original title, I had the impression that the company was going to be acquired by AA. Same... at least they should put an S to aircraft... but then again maybe they hit the strict character limit...

The plural of aircraft is still "aircraft".

sometimes I don't get English...

Re: American Airlines agrees to purchase Boom Supersonic Overture aircraft

#270

Post by adolph »

ahh wrote: post #246
jseutter wrote: post #203

Earlier quoted context omitted.

As far as has ever been discovered - no, this won't work. You can think of a fan as just a prop enclosed in a housing (jet engine). A prop loses effectiveness at the speed of sound because the air passing the prop gets a high pressure shock wave that effectively makes the prop not prop-shaped, so it can't move air. Picture it as using a hammer on glass instead of pushing on glass with your hand, one works way better…

What about the Tu-95? It's famously loud due to (says Wikipedia) supersonic propeller tips. Do you know why they're still effective?

The Tu-95’s props are paired for counter-rotational torque balance. The second prop does not add additional thrust.
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