Skylon

[tartare]

V interesting read here - the ESA report on Skylon and SABRE.
Quite a positive document.
Given they talk of the development cost being ~12bn euros - not far above the A380 development cost - what's the view of people here on whether it'll get built?

[Jane-DoH]

I thought Skylon was cancelled a long time ago? I'm pretty sure this design will go through simply because the price tag is reasonably low (not much different than the A-380), and being unmanned it appeals to all the right elements involved with aircraft design, and politics.

1.) Those who are obsessed with economics
2.) Those who don't want to take any risks ever
3.) Those who like to push the limits of automation (regardless of whether it's needed)

[tartare]

I think it was it's predecessor HOTOL that was cancelled. As far as I am aware, Skylon is still a live project.

[Genghis the Engineer]

Reaction Engines have been pursuing this singlemindedly for a couple of decades - you've got to admire their persistence, and that they keep pushing the best possible technical solutions.

Will it get funded? Frankly, I doubt it, too high cost and too high investment risk - that combination only gets funded by government bodies (e.g. Concorde). That just isn't going to get funded in the current political and financial environment.

Which is a shame, I'd love to work on it.

G

[Jane-DoH]

I assume a turbo-accelerator cycle is an engine-cycle that uses a turbine-based engine to accelerate an airplane up to a higher speed at which it functions as a ramjet, correct?

[Jane-DoH]

For Skylon and for the LAPCAT program, I'm wondering why they didn't put an annular aerospike type nozzle on the design? As far as I know, the technology to make this work had at least been undergoing testing in the late 1960's (it was proposed for the engines used on the Saturn V), it provided something like a 30% improvement in efficiency, and it would be completely compatible with the SABRE, and could probable be incorporated on the Scimitar.

[911slf]

Showing my age here but is anyone taking bets on whether it will fly better than its namesake? Skylon (tower) - Wikipedia, the free encyclopedia)

[Jane-DoH]

Well the fuselage looks like the Skylon tower a lot

[Jane-DoH]

I have two questions

Question One: When was the first time that the ability to produce a sufficiently light-weight pre-cooler came into existence? While Reaction Engines is talking about how advanced their design was, I'd almost swear I read about something McDonnell/McDonnell Douglas did in the past involving pre-cooling the airflow then simultaneously increasing the RPM to improve ram compression efficiency.

I'm not sure if they used a pre-cooler or a MIPCC system or something, but I distinctly remember hearing something about this and a mention that it was similar to Skylon in nature. It was described by an aerospace-engineering professor by the name of Paul Czysz.


Question Two: (Assuming anybody has an answer)
What hypersonic propulsion system has the best power to weight ratio period. How does a PDE boosted ramjet, or a strut-jet RBCC type system compare?

[WillDAQ]

When was the first time that the ability to produce a sufficiently light-weight pre-cooler came into existence?

When Reaction Engines developed it.

The pre-cooler is a very complicated bit of kit and as far as i'm aware RE haven't released the full details of how to get it to work.

[Jane-DoH]

WillDAQ

When Reaction Engines developed it.

Then how is it that Paul Czysz talked about a proposal from McDonnell/McDonnell-Douglas cooling airflow into a gas-turbine, while simultaneously increasing the RPM as the mach number increases (Mach 6, IIRC)?

While I'm not sure if the proposal he was talking about included a precooler or a MIPCC scheme; regardless, there is the Japanese ATREX which also made extensive use of an advanced pre-cooler.