Hypersonic Flight ‘Breakthrough’ Could Have Us in Tokyo by Lunch
wired.com
wired.com
The expansion stage of a brayton cycle engine maximizes exhaust velocity rearward and hence by Newton's third law creates thrust. Constricting the exhaust will only reduce efficiency.
If you're talking about an expansion duct with secondary combustion, that has nothing to do with ram effect and is just an afterburner.
By and large afterburners are hideously inefficient, but many military craft still include them because it is easier to manufacture an afterburner tolerant of secondary combustion temperatures than a turbine. SABRE erodes this motivation as the incident temperature into the flame holders (or rocket nozzles) is dramatically lower than common in a turbine engine, so you can get more of the energy possible from the oxygen density of the engine's intake flow without secondary combustion.
More likely you'll get there for dinner and a night out
At Mach 5 this will take 2h (not considering acceleration/deceleration times)
Of course the military will always be giddy about dropping bombs on whatever poor soul they want as promptly as possible...
The sonic boom however is an issue - Concorde was limited to a small selection of routes that passed mainly over water (e.g. London -> New York) because it was not allowed to go supersonic over a lot of countries. If you could fly supersonic all the way from London to Tokyo, or San Fransisco, or Sydney, then I'm sure it would be worth even more.
If 30% was at 50% of the speed, the total distance covered would be 85% less, adding about 20% flight time increase. Something that normally takes 8+ hours now take 3 or 4 hours. Did this kill the concord?
The linked-to http://news.bbc.co.uk/2/hi/business/2935337 says:
"British Airways […] was reckoned to make a £20m annual operating profit from its London-New York Concorde service."
But also:
"By 1975, the year before commercial launch, more than £1.2bn - at least £11bn today - had been spent."
So, their margin on investment was 1.6% or so, starting about ten years after the investments were made.
They would have needed a lot more planes to get their investments back. To fill them with passengers, fares would have to drop. Lower fares means they needed even more planes, etc.
Concorde also was limited to long distance flights. On shorter routes, its fuel economy did not compensate for a slightly shorter (boarding+flight+deboarding) time.
He's basically saying all that stuff about noise is mostly bunk pushed forward by Boeing to get rid of the competition. You'll note BTW the 747 and Concorde both came out around the same time and you probably also know the 747 was never designed to be a passenger plane. It was designed to be a military cargo plane but lost the contract to Lockheed's C-5A so Boeing needed it to sell as something else.
He, my dad, claims the NYC to LA route was the most lucrative and that without it Concorde didn't stand a change.
I have no idea if there's any evidence to back up his story. Maybe someone else out there has more info.
I'm sure the technology is cool, but would someone please solve the real problem? The real problem is that transportation hasn't improved since the 1960s. In the US, we call exorbitantly-priced, 130-mph trains "high speed", we use airplanes for mid-distance travel and it's ass-expensive as it should be because it makes no economic sense, and most of our transportation relies on burning fossil fuels in tin cans that can't be safely operated above about 90 miles per hour. Solve that one, please.
http://www.bbc.co.uk/newsround/20512131
Tesla is hard at work selling electric cars and making a profit. Google has a self-driving car that works. People are solving problems. Getting hypersonic jets to work would be great.
Now the problem of getting people to adopt any of this in the US? Engineers can't solve those problems. Someday the US will finally get a real high-speed train, but it looks like Japan will have maglevs first.
My malaise is more general. In the 1950s-60s, the economy was growing at 5-6 percent per year because people actually had the vision to invest in basic research and technology. In this day in age, we have a million IUsedThisToilet.com startups built to be acquired, but very little effort going toward real work.
Transportation has improved since the 1960 by a HUGE amount. Modern cars, trains, and airplanes are significantly better (safer, cheaper, more efficient) than those in the 1960s. I'm curious how much travelling you did in the 1960s compared to today?
Water vapor is the largest greenhouse gas, but it's a relatively constant contribution; it's not part of anthropogenic contributions to greenhouse gases (which is usually what people are referring to in this sort of context).
Yes it has. Guess what? There are a lot more people and they want to travel just like you, basic supply and demand. Planes are far more advanced then they were back then.
>>That's what I care about. If this Mach-5 travel costs the same as airfare currently does, and burns a bunch of fucking hydrocarbons to get there, then I'm not impressed.
It will cost more and burn even more hydrocarbons(Of course skylon is an unrealistic satellite launch system and this article makes no sense ). Engineering problems are hard, the development work done in the 1960s is child's play to what is being done now. If things suck so much you should be happy that you will change things for everyone and make a bunch of money in the process.
>> In the US, we call exorbitantly-priced, 130-mph trains "high speed"
They are exorbitantly priced anywhere. We don't get anywhere close to that over an entire distance because existing and even proposed systems (California) won't be fully high speed lines. That isn't a question of technology just simple budget and priorities. No country in the world has replaced mid-distance travel with high speed rail. France is barely finishing out its high speed network that covers a much smaller country than ours.
They'll simply use Evacuated tube maglev(Elon Musk's HYPERLOOP) for long distances, same hypersonic speed.
Looking forward to breakfast in San Fransisco, Lunch in LA, and Dinner in Washinton DC.
Whoops.