How far into the future? An aircraft that launches from a runway and enters low

[publiusr]

Cite.

To start with, there is in flight refueling and familiarity with kerosene handling--that much should be obvious to you.
http://www.ai.mit.edu/projects/im/ma...mans-view.html
"The military is the only organization which really has experience with aerial refueling..."

Also look at figure 2 here http://www.ai.mit.edu/projects/im/ma.../spacast3.html
A quote from the article: "Space operations must become as routine and non-exotic as air operations." Folks are looking at hydrogen peroxide and jet fuel in that neither is a cryogenic.


In what I've read in articles over the years--the general desire is for kerosene spaceplanes.

Some talk on Skylon:
http://hobbyspace.com/nucleus/?itemid=11029

Japans challenges:
http://www.sci.waseda.ac.jp/english/...bject03_3.html
"The phase of the hydrogen in the pipes changes from gas, a saturated vapor (two-phase), to liquid, making it quite difficult to control LH2 mass to feed the engine due to dramatic density changes..."

One solution:
http://www.pmview.com/spaceodysseytw...lvs/sld039.htm

The anti Liberty folks here should enjoy this:
http://www.islandone.org/Launch/boron-sharp-article.htm

Then too, there was the TAV--but that would have needed a pad:
http://www.aircraftdesign.com/rockwe...plane1980s.jpg
http://www.aircraftdesign.com/acpix.html

I always thought it was to be top mount with only the spaceplane in a clamshell bay above ground. Now Antice brought up some good points. Korolov was still pro liquid ICBMs what with R-9 I think it was, saying that it could be fueled rather quickly. So if Skylon can cause folks to "warm" to LH2, that's perfectly fine.

[djellison]

I'll ask you again, publiusr.

Please show where the USAF has stated
"The USAF wants hydrocarbon **for spaceplanes** since it is easier to deal with on short notice"

Not another barely related link fest. Show us where the USAF say they want hydrocarbon fuels for spaceplanes because it is easier to deal with on short notice.

One link. That's all we need.

[publiusr]

And you ignored that link on in-flight refueling. You may not be familiar with the Journal of Spacecraft and rockets over at the AIAA and articles written by all kinds of folks both inside and out of the USAF. If you pay any attention at all, the desire is for non-cryogenics if at all possible.

http://www.theregister.co.uk/2011/01...ved/page2.html
"...hydrogen fuel is cripplingly inconvenient, troublesome and expensive to use: also its low density means that any hydrogen-fuelled vehicle has to be mostly fuel tank." Mark J. Lewis, the USAF's own man is behind hydrocarbon airbreathers--not LH2. If you don't believe what I have to say--then ask him what USAF's stand is.

More:
http://ntrs.nasa.gov/archive/nasa/ca...2001056924.pdf
http://seit.unsw.adfa.edu.au/ojs/ind...viewFile/31/10
http://www.scribd.com/doc/46040828/L...Fuel-1945-1959
http://www.airforce-magazine.com/Mag...paceplane.aspx

"Several factors combine to make the hydrogen engines proposed for the Spaceplane marginal for their task of sending the one-stage airplane into orbit."

From "Future directions of Supersonic Combustion Research" by Julian M. Tishkoff
"With the demise of NASP, the Air Force (AF) has focused its high-speed propulsion effort on storable hydrocarbon-fueled vehicles."

Kay, I. W. et al., "Hydrocarbon Fueled
Scramjet, Vol. VIII, Piloting and Flame
Propagation Investigation," AFAPL TR 68-
146, May 1971.

[djellison]

That's the opinion of the journalist. No where in the quotes from the USAF do they make the statement you're inferring they've made.

I happen to agree that using RP1 rather than H2 makes sense. I am not, for one moment, arguing that statement I just don't want to see you make unsubstantiated claims.

So - I'll ask again - please show me where the USAF have stated ...

""The USAF wants hydrocarbon **for spaceplanes** since it is easier to deal with on short notice""

Not a journalist, not 'all kinds of folk'. Simple request...cite where the USAF have stated that, and we can all move on.

OR - rephrase it and say 'It would make sense for the USAF to persue hydrocarbons for spaceplanes as it's easier to deal with'

Back up your statement - or change it. Right now you're saying they've stated something...but you can't show us when or where.

[Garrison]

And you ignored that link on in-flight refueling. You may not be familiar with the Journal of Spacecraft and rockets over at the AIAA and articles written by all kinds of folks both inside and out of the USAF. If you pay any attention at all, the desire is for non-cryogenics if at all possible.

http://www.theregister.co.uk/2011/01...ved/page2.html
"...hydrogen fuel is cripplingly inconvenient, troublesome and expensive to use: also its low density means that any hydrogen-fuelled vehicle has to be mostly fuel tank." Mark J. Lewis, the USAF's own man is behind hydrocarbon airbreathers--not LH2. If you don't believe what I have to say--then ask him what USAF's stand is.

So all you have is one claim made by an author, who offers no citation for anything that might resemble a USAF source, in fact all he offers for support is his own comparison with the space shuttle. You make such an absolute claim and then produce such pitifully thin evidence to support it.

[Garrison]

That's the opinion of the journalist. No where in the quotes from the USAF do they make the statement you're inferring they've made.

I happen to agree that using RP1 rather than H2 makes sense. I am not, for one moment, arguing that statement I just don't want to see you make unsubstantiated claims.

It does make sense, if you can come up with an engine technology that will give you SSTO using Hydrocarbons. Scramjets are the obvious contender but they don't have that runway take off ability and you still need a rocket engine for orbit since they haven't figured out how to integrate air breathing and rocket modes in the way SABRE theoretically does.

[djellison]

Yup - until we can do with RP1 or others what Sabre does with H2 - I don't see another way of SSTO.

[swampyankee]

One thing to remember is that a USAF SSTO does not need any kind of economic justification, while a commercial launcher, even one which can only be expected to fly non-military government payloads does.

[Garrison]

One thing to remember is that a USAF SSTO does not need any kind of economic justification, while a commercial launcher, even one which can only be expected to fly non-military government payloads does.

True but there simply is no technology available at present for building a 'spaceplane' SSTO with Kerosene regardless of how poor a payload fraction you're willing to accept.

[swampyankee]

True but there simply is no technology available at present for building a 'spaceplane' SSTO with Kerosene regardless of how poor a payload fraction you're willing to accept.

True, but the USAF could also pull in a few tens of billion to develop the enabling technologies.

[Garrison]

True, but the USAF could also pull in a few tens of billion to develop the enabling technologies.

They've spent considerable sums on technology like scramjets; without so far getting any closer to anything that would resemble a Kerosene SSTO. As fas I can see no one knows what such 'enabling technologies' might be. This isn't about financial clout or a willingness to sacrifice efficiency for expediency, there just isn't currently even an idea how to do such a thing.

[NEOWatcher]

A couple of points re wingloading. ... If its wing is as good as a 747's, which is doubtful, it's takeoff speed would be about 280 knots.

I always like to see numbers when sometimes the conversation turns to opinion. Thanks.
I'm not sure what your statement concludes in though.
The takeoff speed of Skylon is almost exactly that (they state Mach 0.5). So; is this only a comment on the structure of Skylon's wings?

I suspect that the tire life is going to be rather short....

I agree. Or perhaps they will extend thier cryogenic cooling to the tires.

[Hal37214]

I agree. Or perhaps they will extend thier cryogenic cooling to the tires.

Seems it could be safer and more economical to launch from a sled, saving the tires for landing the light-weight return vehicle.

[kamaz]

USAF did study kerosene/H2O2 spaceplane in 1990s. The project was named Black Horse.

http://www.ai.mit.edu/projects/im/ma...ack-horse.html
http://www.astronautix.com/lvs/blahorse.htm
http://www.islandone.org/Launch/Blac...pTransfer.html

ETA: Somewhat related, XCOR Lynx runs on kerosene/LOX: http://en.wikipedia.org/wiki/Lynx_%28spacecraft%29

[Antice]

Seems it could be safer and more economical to launch from a sled, saving the tires for landing the light-weight return vehicle.

Except that when REL did a study of that for the HOTOL system, they found that a sled added both complexity and cost compared to just having a beefed up landing gear.
It all depends on how beefed you need to go, so this is propably a case by case thing.

[Garrison]

USAF did study kerosene/H2O2 spaceplane in 1990s. The project was named Black Horse.

http://www.ai.mit.edu/projects/im/ma...ack-horse.html
http://www.astronautix.com/lvs/blahorse.htm
http://www.islandone.org/Launch/Blac...pTransfer.html

ETA: Somewhat related, XCOR Lynx runs on kerosene/LOX: http://en.wikipedia.org/wiki/Lynx_%28spacecraft%29

Well Lynx is suborbital, and seems to have a worse payload fraction than its Virgin Galactic counterpart, which is what you would expect. Blackhorse seems to be a workaround on the carrying fuel issue but it doesn't seem to have gone anywhere; unless there's a Black Project out there that's remained a secret.

[swampyankee]

I always like to see numbers when sometimes the conversation turns to opinion. Thanks.
I'm not sure what your statement concludes in though.
The takeoff speed of Skylon is almost exactly that (they state Mach 0.5). So; is this only a comment on the structure of Skylon's wings?


I agree. Or perhaps they will extend thier cryogenic cooling to the tires.

Not bad -- eyeball the aspect ratio and get pretty close to the expected take off speed. (pats self on back). No; my comment was on the aerodynamics of the wing.

[mhutiubih]

Yes, this is an extreme possibilty and could be done right now. The proplem would be stering the craft once in the upper atmosphere and also in outer space with the same control as if it were still in the atmosphere. Then we would need to make a propulsion system capable of both inner and outer atmospheric thrust. An electrothermal propulsion system would do just fine.

spacepropulsion.blogspot.com

here you can find not just electrothermal propulsion being explained but also other electric propulsion devices possible for use in a trans atmospheric shuttle.

[Garrison]

Yes, this is an extreme possibilty and could be done right now. The proplem would be stering the craft once in the upper atmosphere and also in outer space with the same control as if it were still in the atmosphere. Then we would need to make a propulsion system capable of both inner and outer atmospheric thrust. An electrothermal propulsion system would do just fine.

Or the SABRE, which seems rather more plausible.

[danscope]

In space, you require attitude thrusters. No question.

[Jens]

In space, you require attitude thrusters. No question.

You don't really need attitude thrusters. You do need them if you want to control your attitude, of course. If you're happy to tumble away with no control, then they're not really necessary.

[kamaz]

There are also reaction wheels...

[danscope]

When you design spacecraft, and quite a few other things, you have to be concious of "the weight" .

[Ara Pacis]

When you design spacecraft, and quite a few other things, you have to be concious of "the weight" .

"The mass" fyp

[danscope]

Yes, well put. In space, it's mass.

[Antice]

Yes, well put. In space, it's mass.

What was the point of your last 2 posts?
and what relevance does this has to do with skylon?

[danscope]

Even the X-15 had attitude thrusters.

[Antice]

Even the X-15 had attitude thrusters.

So does the planned skylon. The system is going to be mounted in the tail end of the vehicle. it's going to have it's own little set of fuel tanks and all. It's pretty much a requirement for any orbiting device to have some sort of reaction controll system after all. even if one do try to mainly control attitude trough the use of gyroscopes. Gyroscopes runs the risk of becoming saturated after a while after all.

[swampyankee]

Gyroscopes are not likely to be fast enough (or produce large enough moments) during reentry.

[Antice]

Gyroscopes are not likely to be fast enough (or produce large enough moments) during reentry.

It's my understanding that gyroscopes are best used for long duration stability needing vehicles like satellites, where fuel mass is a major limiting factor for service life, and not for a rapidly maneuvering short duration vehicle like capsules and other launch vehicles. you always need to have RCS thrusters on your vehicle. those are the engines that get you into your final position, as well as giving you the capability to desaturate the gyroscopes you might have if they are present. For a short duration mission like that witch a skylon is designed for you don't save nearly enough fuel mass to justify the added mass and complexity of command gyroscopes tho.