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Proposed Lapcat II Hypersonic Airliner: Brussels to Sydney in Less Than 3 Hours
New submitter AG_2011 writes: Could an airliner that flies anywhere in under 3 hours be in service by 2030? One estimate puts the cost one way at €5,000 (£3,700) per seat for a Brussels to Sydney trip. The Lapcat-II project's Mach 8 airliner will be capable of 8,500 km/h (5,280 mph) and could take passengers on this trip in 2 hours and 55 minutes. The race is on...
"What’s more, liquid hydrogen fuel is not highly combustible mid-flight. Although hydrogen can be ignited, the risks of an explosion or fire are lower compared to conventional airline kerosene fuel"
Gaseous hydrogen is already a ridiculous explosive risk. Liquifying it only makes the resulting explosions bigger. They somehow think this is safer than Jet-A, which is actually less flammable than gasoline.
There are valid engineering reasons for the use of liquid hydrogen as a fuel, such as specific impulse or heat capacity. But safety is absolutely not one of them.
In other news, this is a blatantly obvious attempt to get funding for SSTO spacecraft development by disguising it as a less outlandish business plan. Seriously, this has much more in common with Skylon or VentureStar than with Concorde, right down to the choice of fuel. I wouldn't be surprised if many of the engineers are the same.
Why not Mach 22
If you first want to go fast, why not just use an intercontinental ballistic missile? It is really simple construction (read fuel tank with orifice), uses cheap fuel, and really need no fancy aerodynamics or control system. Just aim and fire.
The whole idea of pushing a vessel through air for hours and hours, wasting fuel, when it can glide with no friction a few miles higher seems dumb. It also consumes more fuel in total.
don't cut it off www.mgmbill.org
One correction to your math. At high Mach, the curvature of the earth creates a "virtual" L/D improvement. For example at Mach 22, you will have a L/D ratio better than 100 for a grand piano filled with tungsten.
don't cut it off www.mgmbill.org
Mach 2 engines *were* more efficient at the time the concorde was built. In the mean time however, more efficient engines have been built: compressors have got better, but crucially, people have figured how to make turbofans efficiently have extremely high bypass ratios. So while the core might be more efficient at Mach 2, the overall production of thrust isn't, unfortunately.
SJW n. One who posts facts.