A2

What goes around comes around.

The artist\’s impression looks like something out of a science fiction film. But a hypersonic passenger plane that could fly to Australia from northern Europe in less than five hours has been designed in Britain. With funding from the European Space Agency, a team of engineers and scientists has come up with the A2, a plane they believe could carry 300 passengers at a top speed of more than 3,000mph.

This looks to me like a retread of the HOTOL concept: it\’s even got the same person designing the engines, Alan Bond. The thing is though that we now know that hypersonic engines do indeed work: we\’ve even supplied bits for a US military version of one that has been tested. Whether they are economic is of couse another matter.

Have to admit I don\’t get this:

A spin-off is that liquid hydrogen is potentially much greener than conventional fuel – rather than producing vast amounts of carbon emissions it gives off water vapour and nitrous oxide.

Given that NOx has a carbon equivalenteffect 296 times greater than CO2 I\’m not sure that\’s much of an advance. But, umm, how does burning H2 in O2 from the atmosphere create NOx?

Any chemists out there?

4 comments on “A2

  1. Because you can combine atmospheric nitrogen with atmospheric oxygen to make NOxes. It just requires energy (in the form of heat: effectively “burning” the nitrogen). The NOxes break down again (they are unstable like ozone is) but it takes time and they do their nasty heat-up-the-planet job before then.

    “The thing is though that we now know that hypersonic engines do indeed work: we’ve even supplied bits for a US military version of one that has been tested. ”

    Hmmn. I think the real interest in hypersonic stuff is more to do with guided inter-continental missiles rather than taking besuited chubby people to Australia in a few hours.

    Tim adds: Indeed, hypersonic cruise missiles. You coat the inside of the engines with hafnium carbide.

  2. hafnium carbide – I can imagine it being a bugger to manufacture; what with that density and melting point. Tricky.

    As for the NOx generation dead on; N2 is one of the main components of air so there’s plenty flying around when you burn hydrogen in air.

    Fraid my background in chemistry fails a bit there – I was a organic chemist.

    Tim adds: I don’t really know how it was done either. Got boffins for that. But I think we baked hafnium oxide with fine carbon powder. The melting point is what they were after of couse: the insides of a hypersonic engine get pretty hot!

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