UK Skylon spaceplane passes key review (from runway to orbit)

BBC ^ | May 24, 2011 | Jonathan Amos

[Talisker]

There is no way anything with that little of a wing can lift enough fuel & oxidizer to make it to orbit, let alone lift off only half way down the runway. With that long a fuselage aft of the main gear it could not have that much angle of THAT close to the runway.

Speed.

Speed, speed and more speed.

Which requires fuel, fuel and more fuel.

Unless, of course, they've got a large magnetic field torus rotating at about 10 million rpms in the center of the thing, to reduce it's gravitational attraction, and lessen its weight.

In which case they can do it right, and include a grand piano and a cocktail lounge.

: )

[Ol' Dan Tucker]

Not much for wings. Must have a REALLY high stall speed.

Fuselage lift contributes quite a bit. The F-104 was the same way.

[SunkenCiv]

Thanks decimon.

...its Sabre engine... is designed to breathe oxygen from the air in the early phases of flight -- just like jet engines -- before switching to full rocket mode as the Skylon vehicle climbs out of the atmosphere. It is the spaceplane's "single-stage-to-orbit" operation and its re-usability that makes Skylon such an enticing prospect and one that could substantially reduce the cost of space activity, say its proponents.

It'll cut the cost to put two astronauts into LEO from half a billion to about $100 million. Of course the $500 Shuttle launches put more than two astronauts up there, and also carry sizeable payloads, which this thing won't do.

Like all SSTOs -- as well as their staged brethren -- most of the weight lies in its fuel. Since there's just one fuselage, most of the interior of this craft will be fuel and oxidizer.

To make a hybrid engine work means variable inlet geometry to start with, and to cut weight, multiple-duty fuel system components. Bravo if they make it work, but it's not worth doing except to show off.

The point of reusability is reusability, it won't cut costs. The only thing that matters in a human-rated spacecraft is reliability, and the reusable STS hasn't quite delivered on that. Reliability doesn't increase costs, it reduces costs. And reusability doesn't increase reliability, but it does increase costs, despite claims.

[SunkenCiv]

http://visual.merriam-webster.com/images/astronomy/astronautics/space-launcher/cross-section-space-launcher-(saturn-v)_2.jpg
http://visual.merriam-webster.com/astronomy/astronautics/space-launcher/cross-section-space-launcher-(saturn-v)_2.php

[ZOOKER]

[SunkenCiv]

The nose (that canard-looking tip) looks like Von Braun’s proposed Mars vehicle; overall, it reminds me of the SR-71. The variable geometry inlet on the proposed engine appears to work the same way as the SR-71’s engine.

[KevinDavis]

[BwanaNdege]

Yea, raw thrust works when you don’t have gross mass!

“the mass fraction of an SSTO would have to be about 0.87, which means the structure and payload of the vehicle is 13% of the total weight of the fueled vehicle”

http://vorlon.case.edu/~jam64/work/ssto.htm

[GeronL]

Now for a manned vehicle

[decimon]

...overall, it reminds me of the SR-71.

The two humungo engines back there.

Don't know what you were saying in post #23 but I believe this thing is pilotless. Guess any useless humans would be cargo.

[colorado tanker]

Looks sorta like this:

[cruise_missile]

I meant the Airbus A380.

I was trying to point out the engineering prowess that we have lost.

[ZOOKER]

...“the mass fraction of an SSTO would have to be about 0.87, which means the structure and payload of the vehicle is 13% of the total weight of the fueled vehicle”...Since it breathes air until it leaves the atmosphere, they don't have to lift as much liquid oxygen and your calculations may not apply. Note the two large Hydrogen tanks and only one, smaller oxygen tank.

OTOH you add weight due to the complex engines, compressors, etc. Dunno if they can make it work but apparently they think so.

[SunkenCiv]

http://www.reactionengines.co.uk/images_skylon.html

http://www.reactionengines.co.uk/images_sabre.html

http://www.reactionengines.co.uk/lapcat_movieqt/LAPCAT%2016.mov

http://www.reactionengines.co.uk/lapcat_anim.html

[SunkenCiv]

Yeah, it’s pilotless.

Hence, the point of having a reusable craft with a 10 ton payload — a size handled by a number of today’s disposable boosters — vanishes, just like that.

The craft doesn’t have to return if there’s no one aboard. Every kilo of returning hardware represents payload that can’t be delivered to orbit.

[SunkenCiv]

Thanks BwanaNdege. Dang, Zubrin almost got it right:

...has concluded that there are three points necessary for a cheap reusable launch vehicle: it must "(a) have a high launch rate, (b) have a small ground staff, and (c) reuse the first stage." He goes on to say that the only way to accomplish both (a) and (b) simultaneously is to have an extremely simple launch system, and since adding additional stages adds complexity, the simplest solution is a single stage vehicle. Given a higher launch rate and lower operating costs, a single-stage-to-orbit vehicle will open LEO to human occupancy.

Reusing the first stage can result in a higher launch rate; the Saturn V booster could have been retrieved, inspected, serviced, and refueled. The F1 engines were stand-tested far longer than they'd have to burn in flight, so ten to fifteen launches wouldn't have been out of the ordinary. That was the workhorse that put literally every other needed system on its way to the Moon (and back).

SSTO adds complexity, lengthens turnaround time, raises operating costs, and reduces effective payload. So, once again, Zubrin's wrong.

[wastedyears]

Sounds like Cylon...

[wastedyears]

Just Googled that movie because I might have seen it years ago, I think the planet’s name was Bellas.

Turns out it’s being remade with a release date for next year.

http://www.imdb.com/title/tt0455856/

[SunkenCiv]

Bingo.

This proposal means added complexity, maintenance issues, cost spirals, all to reduce the needed amount of liquid oxygen.

Dumping the air-breathing nonsense, and using aerodynamics to substitute for part of the altitude gained through rockets (which are the most efficient chemical engines ever devised), regeneratively cooled 100% cryofueled engines pushing a winged vehicle would be cheaper, still reusable (to the extent that any and all machinery wears out), and would beat this Skylon / Sabre idea.

Rather than an SSTO, a staged vehicle — not unlike the original concepts that morphed into the Shuttle, and for that matter, not unlike Rutan’s suborbital system — would solve some problems, and greatly increase payload to orbit. The large winged mothership would take off, and could even be an air-breather, carrying only fuel and the winged upper stage or stages on its back, getting it to its max altitude. After separation, the mothership would turn around and mostly glide all the way back to the launch site. It would require some fuel to finish the trip.

The second stage of a two-stage version would have an engine that would use onboard fuel and oxidizer and wings to reach orbital velocity and altitude. In the two-stage version, if man-rated it would be a reentry vehicle, and might be anyway.

The third stage of a three-stage version would be a smaller, fast, expendible booster, with no wings as it would have ridden past the officially defined boundary of space.

I should point out that this approach was studied and was found to deliver less payload to orbit than just shooting it straight up there with a rocket. :’)

[r9etb]

He's predicting around $450/lb. to LEO, I think SpaceX will probably have a rocket providing that price to orbit before this ever leaves the ground.

Where have we seen those sorts of predictions before...?

FWIW, the price of SpaceX rockets is rising, and we can expect it to increase more as they find out that the market for their product isn't nearly so robust as they'd assumed. Infrastructure is expensive, and you've gotta keep it around even if nobody's buying this month. (And forget about that "commercial" stuff: most of their money comes from NASA....)