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Launching Spacecraft From Aircraft
Embedded Geek writes: "New Scientist has an article on a proposed launch scheme named 'Bladerunner' (presumably, someone is a P.K. Dick fan) that would
use a pneumatic launcher to shove a launch vehicle out the back of a military transport aircraft at high altitude (40,000 feet/12,000 meters). As with all the new systems (such as this one) the goal is to reduce launch costs to more reasonable levels (to about $6K/kilo from today's $11-44K). An existing Pegasus system uses dedicated B-52s with the vehicle slung underneath, but Bladerunner would be an improvement by not requiring dedicated planes (the launcher could be set up on a transport in 24 hours) and also could accomodate larger vehicles (since it wouldn't be slung underneath)."
...but this won't work with larger spacecrafts ?
I can see them using this for smaller satellites
but they'll have a hard time to fit a shuttle into a military transport (ok, they might saw off the wings)
Owner of a Mensa membership card.
According to the Pegasus link in the submission, the Pegasus system uses a modified Lockheed L-1011 airliner jet named Stargazer, not B-52s. Methinks someone has overdosed on CNN again...
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Instead of on massive boondoggles like the ISS. What people don't seem to get is that it all comes down to price per kilo to orbit - if we can't get that price down we are never going to have a sustainable presence in space.
NASA has absolutely no incentive to reasearch alternative (and cheaper) launch methodologies because they are politically committed to the space shuttle (another massive boondoggle).
I say we tell NASA they can keep the ISS, if and only if they can produce a launch vehicle which is capable of sending a thousand pound payload into orbit for 1/10th the current cost. Then we might see some progress on this front.
IIRC, airships are much cheaper per kilo than other aircraft, so surely they would be more suitable for slinging great big pneumatic guns on if you're going for the ultimate cheap solution? Of course, airships are quite slow, but they can carry heavy loads - e.g. the CargoLifter, mentioned here.
Of course, a space-lift would be both much cooler, and much cheaper (ISTR figures of $210 per human for an up-trip, or $40 for a round trip, as on the way down your delta-GPE could be converted back into electricity; presumably this is ignoring R&D and build costs). NASA was mumbling about this about a year ago, but surely such a project would cost billions (and with the US governmental system, it probably won't happen unless a forthcoming, insightful (gasp!) President decides it's important for the future of the US, and can convert/convince a whole lot of people...
James F.
The term "Bladerunner" is imho not a P.K.Dick-Term. The Story is entitled "Do Androids Dream Of Electric Sheep", the title "Bladerunner" was first used in the movie by R. Scott.
Can anyboy enlighten me where it is from?
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Could be worse. Could be raining.
Orbital uses their own L-1011 to launch the Pegasus these days. The B-52 was used during their X-Plane phase before they knew it would work and could make them money.
-- Instant Karma's gonna get you! [320848 = 2*2*2*2*11*1823]
How does the pilot of the launching aircraft deal with the huge changes in the center-of-gravity when a large missile (Pegasus XL weighs about 50,000 lbs) is ejected from the rear of the aircraft.
Mea navis aericumbens anguillis abundat
Because they used all base 11 numbers for cost statistics. Which means some engineer just did an off the cuff calculation. Which means the bean counters have not thrown in their 600% markup for administrative costs. And the congressmen have not thrown their 50 state's billion dollar pet rocks aboard "for safety" and doubled the cost again.
If voting were effective, it would be illegal by now.
The US Military (who else?) tried this in the '60s with Minuteman ICBMs. Except they used a C5 Galaxy transport and a parachute. I believe the few tests worked well enough, but it was never adopted as an operational launch method: to be effective for nuclear deterrent would have required a fleet of C5s (only ~50 were built and they were built for heavy airlift), continuously airborne. Turns out to be cheaper to stick the Minutemans on the back of a train and drive it around the country (who'd a thunk?).
Anyway, as a commercial enterprise for smallsat launches, this would appear to be a workable solution - use a ram instead of expensive parachutes, and fly the transport down to the equator before launch (same trick that SeaLaunch uses). I just hope the launch vehicle is a bit more reliable than the competitor - Pegasus. They've had a bit of a run of bad luck recently...
--
I'd rather have a bottle in front of me than a frontal lobotomy
The space shuttle originally was supposed to operate this way, with one plane carrying the spacecraft part to high altitude and then rocketing from there. It was rejected because it required developing a big plane as well as the shuttle. This method may be an improvement over that proposal.
So long and thanks for all the fish . . . !!!
Considering 1000m/s as a minimum speed for scramjets, then you'd have to drop from 100km altitude to achieve this (very conservative) speed.
Doing the maths is the difference between science and science fiction. (With the exception of mars missions.)
Price per kilo to orbit is NOT the only hurdle! I can see three major obstacles off the top of my head:
No Funding: Who in this age of recession is foolhardy enough to finance such a venture after all the venture capital firms got burned in last years crash?
Payload design: Modern satellites are custom designed to match their launchers. Diameter, mass, etc are optimized during the design stages to the specifications of the intended launcher. Who exactly is going to redesign their multi-million dollar satellites for the unique constraints used in this design?
Market: Who will be buying? Any air lauched design is going to be limited by the launch aircraft, in Pegasus's (L1011) case by aircraft's undercarriage, and in Bladerunner's (Which aircraft? C131/C5/C17's? Good luck in convincing the USAF to lend you one, they are waaay overtasked already.) by cargo bay weight constraints. Since Iridium chapter 11'ed the market for lightweight sats in LEO has almost completely evaporated.
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Besides the wonderful loss of mass from dumping the payload - which I believe should not be a major issue, the article fails to tell how this pneumatic expulsion of the rocket will affect the launching aircraft.
.. un uh... no way
Wouldn't this put a lot of stress on the launch craft? Let alone the requirement of moving near the speed of sound (I would think 500+) would also be an issue for the plane.... I cannot imagine what happens to the plane if something if the pneumatic process goes awry...
IOW - I would not fly with it
* Winners compare their achievements to their goals, losers compare theirs to that of others.
For an orbit at 200km, the required energy to raise the satellite is 2MJ/kg. The required energy to accelerate the satellite from zero to the orbital velocity is 28MJ/kg, or only 24.5 MJ/kg for an earth-rotation assist from cape canaveral.
In any case the energy savings by lifting the payload to 20km are minimal at best. Most of the advantage comes from being weather independant, due to being above the clouds.
It's pretty clear why there's no great energy being directed at these systems.
The test firing (it was about this time last year I think) must have been important because all sorts of VIPs from NASA and the Air Force showed up, which didn't normally happen.
I've said it before and I'll say it again: Test firings are cool! The shockwave hitting you is really a unique experience.
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Another idea along this line is the joint MIT / US Air Force project called Black Horse. The key idea behind the Black Horse is that it can be aerially `refueled' from a tanker such as the USAF KC-135. This has caused some people to describe it as `stage-and-a-half' rather than a true SSTO vehicle. It will take off and land horizontally from a runway, and will be piloted by human pilots. Two demonstration vehicles were planned as stepping stones to the Black Horse, called the Black Foal and the Black Colt. The Foal would demonstrate aspects of the technology and provide proof of concept. The Colt would fly to half orbital velocity and utilize an off-the-shelf `kick-stage' to put satellites in orbit.
The task of getting it into orbit is likely somewhat trivial. As a cost cutting measure, I can see not having to use a booster stage.
but then you would not have all of those fancy PR events for Nasa to toot its' horn
"It is a greater offense to steal men's labor, than their clothes"
Though unfortunately not available online, the June/July 2001 issue of Air & Space has a nice article on NASA's B-52B that's used for launching experimental aircraft. According to the piece the plane is a vintage plane buff's wet dream, with the vast majority of the avionics dating back to the '50s, unlike its younger USAF siblings, whose electronics have been pretty regularly upgraded since rolling off the assembly line in the '50s and early '60s.
Apparently NASA has been in the market for a newer B-52 for some time since their plane is so old that spare parts are becoming something of a concern, but so far the USAF hasn't lent them a potential replacement that they've really liked.
Of course, a space-lift would be both much cooler, and much cheaper (ISTR figures of $210 per human for an up-trip, or $40 for a round trip, as on the way down your delta-GPE could be converted back into electricity; presumably this is ignoring R&D and build costs). NASA was mumbling about this about a year ago, but surely such a project would cost billions...
If you mean a space elevator as in "Red Mars" or that Arthur C. Clarke book, it'd cost a lot more than "billions", unless you mean "1000's of billions" by that. I don't think there's any material yet developed that could accomodate the engineering demands of such a project, and is available in such massive quantities. Plus all the orbital infrastructure needed to build the sucker, and all the spacecraft needed to transport things to orbit, and/or mine asteroids for raw materials. A vast undertaking, to say the least. Needless to say, it WOULD be the most economical way to reach orbit, on a per-kilo basis. Human society would be revolutionized - I hope to see such a project given serious consideration within my lifetime, but I suspect the political will to do so is lacking.
Freedom: "I won't!"
Half true. The shuttle is a huge political stone around NASA's neck, but there is still a strong desire in most of the agency to get launch costs down and reliability up.
The simple reality of the situation is that rocketry is hard. Here's a partial list of commercial enterprises trying to get in on it:
And of course the big boys like Boeing, Lock-Mart, and all the various non-Amurrican folks like Russia, China, Japan, and the EU.
Any of these enterprises would be, er, on top of the world if they could develop a low cost launch vehicle. It's much easier to grumble about how expensive access to space is than it is to actually do something about it. Whether NASA is going about it in a sensible way is a separate question, but it's not like all they're just sitting on their duffs waiting for the right incentive.
Yes, sorry, I meant English billions (i.e. units of 1e12 dollars).
James F.
I seem to recall that DoD experimented with a similar idea in the '60s. A Polaris-like missile was pulled from the back of a cargo aircraft (C-130 or C-141) and, once hanging suspended, fired. The idea was dropped for several reasons, one of which was that it was not possible the accurately position the missile (vagaries of wind, chutes, etc.) accurately enough for accurate targeting. Perhaps modern computers can compensate for this.
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I think that the shuttle needs to be privatised. But who would take it?
The way you sell it is to give a guaranteed launch contract i.e. all the dough the government would have paid out anyway for the next few years as a sweetner.
After the contract has run out, then the company will either have made the shuttle cheap enough to continue to fly, or THEY will shut the shuttle down. Either way the government has clean hands... and their favourite boondoggle the ISS can continue on and give something to launch TO.
It also gets the government out of the launch platform business- which is deeply unprofitable right now anyway for them; but that's Ok, the current contractors in the US can keep on launching fine; they're growing atleast.
-WolfWithoutAClause
"Gravity is only a theory, not a fact!"A Pegasus is carried under one wing, where it presents an asymmetrical load. There is only so much that an aircraft can carry that way. Its drag is also asymmetrical, and there are ground-clearance and interference drag issues. This limits how fast the carrier aircraft can fly, how high it can go before launch, and even if it can get off the ground with a heavier load (if it can't rotate to takeoff attitude without scraping the rocket's tail on the ground, you can't take off).
Putting the rocket inside the aircraft creates one problem, which is a mechanism to extend the wing; there may also be some issues with drag from the modified cargo doors. Other than that it's all positive:
- The weight is carried in the center, where it is symmetrical.
- Nothing extends beyond the aircraft; there are no new difficulties with ground clearance.
- Drag isn't changed much, so the aircraft can launch the spacecraft from a greater speed and altitude. This improves the spacecraft's performance and carrying capacity to orbit.
While the price drop probably isn't enough to create much new market for launch services, it's a good start.Scientists restrict study to entire physical universe; creationist
It's been done many times; it's called a "rockoon". It doesn't work so well for heavier rockets, though; high-altitude balloons can't support very much weight per unit volume. Launching the balloons can be a real challenge too.
Scientists restrict study to entire physical universe; creationist
The change in CG is temporary. If the rocket is ejected by compressed air at 1 G, it will be 145 feet behind its starting point in 3 seconds. The pilot can apply down-elevator to compensate for this, but it's probably not necessary. It may not even be desirable, as you want the rocket sliding out the back of the aircraft smoothly and not hanging up due to torque forces. For that scenario you could begin by flying a small arc with the nose pitching downward just as ejection begins, reverse the pitch change during ejection, and then pitch down again after ejection. Really figuring this out needs a bunch of aircraft experts with a good computer simulation, not a single-engine-land guy with a physics habit doing hand-waving on Slashdot.
Scientists restrict study to entire physical universe; creationist
Most of the fuel use by a modern rocket occurs just getting off the launch pad. Current launch systems work by placing the rocket in a vertical position on the launch pad before liftoff, and the rocket lifts straight up before performing what's called a "roll maneuver" (this is unmistakable on the Space Shuttle, but "regular" cylindrical rockets do it as well) to get into the correct attitude for the rest of the flight. This is an incredibly energy-inefficient method, but the rockets are designed to work this way.
Consider also that most launches take place from sea level (the Sea Launch converted oil platform is a perfect example) where the earth's atmosphere is thickest, causing a lot of reistance that has to be overcome by the force of the rocket motors. At 40,000 feet, the atmosphere is far thinner (consider that humans have to wear breathing masks above 10,000) so there's less fuel used just burning through the lower atmosphere.
There is also a velocity bonus that comes from launching this way. A rocket lifting off from the earth's surface is only getting a "free" boost from the speed at which the ground moves at that latitude, explaining why the equator is the best latitude for launches and why Sea Launch tries to get as close to it as possible. An air-launched rocket like Pegasus gets the "free" velocity bonus from the launching aircraft in addition to that from the earth's rotation.
So... let the aircraft, which costs far far less to operate (we don't have rockets in every garage, but I know a few pilots) do most of the hard work and then let the rocket literally piggyback on that. (Yes, I know full well that Pegasus rides under the L-1011!)
i am a soviet space shuttle
- Civilian planes don't have military power; a likely aircraft for this would be an older Boeing 7x7.
- The article said that the rocket would be ejected by compressed air. This means that gravity doesn't have to do the job, and the spacecraft and carrier plane will have what is known as "positive separation".
- A shift in attitude at such altitudes wouldn't be a big deal; there is plenty of airspeed and time to recover even if the wing is stalled. The two things that have to be respected are maneuvering speed (the indicated airspeed below which the wing will stall before the airframe is overloaded), and that the worst-case upset doesn't move the aircraft to an attitude from which it cannot be recovered.
- Ejecting a center-mounted load directly rearward isn't going to apply a yaw torque, so a spin is extremely unlikely (a spin requires an asymmetrical stall condition in the first place).
Just some questionable wisdom from a pleasure pilot.Scientists restrict study to entire physical universe; creationist
That's Buran, the Soviet space shuttle. This photo is showing the Russian/Soviet equivalent of the U.S. Shuttle Carrier Aircraft. I do believe the An-225 might have been custom-developed for this purpose, an extremely expensive proposition. The United States, on the other hand, transports the shuttle orbiters on a widely-available commercial aircraft -- in fact, the early photographs of the SCA clearly reveal American Airlines markings faintly visible on the skin of the plane! (Both 747s have since been repainted white with a blue stripe.)
They are not stock, though:
Modifications to tail to counter increased wake turbulence from Orbiter
SCA without orbiter, displaying attachment fittings like those on External Tank
SCA carrying orbiter Enterprise about to land
N905NA served with American until 1974. The other, N911NA, is from Japan Air Lines and was acquired by NASA in 1988.
I've got pictures of one of the Buran test articles if you're wondering how this Soviet version of the Space Shuttle looks from up close.
i am a soviet space shuttle
Slashdot has reported on the Canadian entry into the XPrize contest. The DeVinci project intends to raise there rocket to high altitudes via baloon and launch from there. Perfect example of the KISS principle well applied.
Good Luck to them.
- When a rocket takes off from the ground, it is throwing away gas at many times the speed of sound while it's moving very slowly. If you calculate the amount of energy which actually accrues to the rocket versus what disappears as heat and noise with the exhaust gas, the efficiency is dismal. Launching from an aircraft allows the rocket to begin operating at a much higher efficiency; indeed, the air-launched rocket starts at a speed and altitude that the ground-launched rocket may have to burn half of its mass to reach.
- Nozzles cost about the same, but a nozzle with a bigger bell can expand the gases more and get more thrust out of them. More thrust for the same fuel means more payload to orbit, and costs go down. You can't use a large-bell nozzle on a launch from the ground because the gases would be over-expanded, separate from the nozzle walls and cost you badly in efficiency and thrust. This means that the rocket launching from high altitude has an advantage which goes well beyond starting a bit higher.
- The payload at the end of a rocket burn is an exponential function of the delta-V (the more speed you have to put on, the more of your vehicle has to be fuel and the less is payload); getting a 550-600 MPH or so head-start helps a lot. So does the aerodynamic lift of the wing, which is effectively "vertical thrust" that comes for a fraction of the fuel required to produce the same with rocket fuel.
Hope that helped.Scientists restrict study to entire physical universe; creationist
Funding: there's ways of developing it that don't cost too much money. They're slow, and they require volunteer time from engineers (which can be obtained for working on a cool project, so long as there's not too much pressure from management), but they can be done.
Payload design: ok, so build your launcher to the same specifications as existing ones, and treat them as de facto standards. That's what standards are for: to allow people to build to then instead of vendor-specific specifications.
Market: this is the most significant of these three challenges, though there are solutions even here. Space tourism, for instance, though you need to really get launch costs down (to below $100/lb) before this becomes viable. And if you've designed to, say, NASA"s specs and can outperform NASA, there may well be some US gov't contracts who wouldn't mind not dealing with another beauracracy - so long as you can put up with their beauracracy, of course.
Most of the fuel use by a modern rocket occurs just getting off the launch pad.
Incorrect, if you mean "getting from the launch pad into space before acquiring orbital velocity". Less than half of the fuel is used in that stage; it's actually more like a third. Still non-zero, true.
I seem to recall this sort of system being considered for use with the Avro Arrow - at least during the CBC 'Arrow' docu-movie, mention was made of it. At 70,000 feet, though!
Does anyone remember the Avro Arrow?
I seem to remember that these guys toyed with the launch vehicle concept back in the 1950's. The Arrow had a huge internal missile bay, larger than that of a B-29.
Yes, it was scrapped, and the people there mustn't have had much talent. After all they did end up contributing to the Concorde, Mercury program, Gemini spacecraft, Lunar Orbit Rendezvous (LOR), lunar module, Apollo program, and Mission Control.
Learn all about what almost was... courtesy of your neighbors to the north:
http://www.exn.ca/FlightDeck/Arrow/
The MX-Missile's steam cannon launch already works economically and reliably. Scaling it up should be relatively straight-forward, as long as you avoid the fate of Gerald Bull.
Seastead this.
Of course, it's not without risk: the day before the demo I saw a C-130 took an excursion into the woods when they did it. Killed everyone on board. Then again, you're doing major CG shifts 50 feet off the ground...
"Seven Deadly Sins? I thought it was a to-do list!"
To reach orbital velocity of several times your exhaust velocity, about 80 percent of your rocket needs to be fuel (and you need high specific impulse fuel to boot). Engineers build rockets that are 20 percent structure and 80 percent fuel, but you have to launch 'em verticaly because you can't lay 'em on their sides. And you have no payload.
So you stage two 80 percent mass-fraction rockets, the second stage being itself 20 percent of the first stage, and the payload being 20 percent of the second stage. Your payload is about 4 percent of the whole shebang, but at least you get a payload. Your payloaded mass fraction is down to 66 percent for each stage, and taking inefficiency of the vertical launch and less-than-ideal specific impulse, you reach orbit.
Since the rocket equation is logarithmic and since each ''payload'' is in the same ratio to the stage underneath, your booster stage (fuel, structure, and motor) is about 80 percent of the whole stack. Owing to the inefficiency of the vertical launch and air resistance in the lower atmosphere (which you are climbing like a bat-out-of-you-know-where to get through with as little loss as possible), the first stage does not take you to quite half of orbital velocity, but it takes you well out of the atmosphere and at many multiples of the speed of sound. This is well beyond the performance of any jet plane.
In fact, the early 2-stage Shuttle proposals followed this ratio of stages quite closely. The consequence was that the first stage was this behemoth -- roughly the outlines of a 747 but much heavier when loaded with fuel -- that had to fly an exoatmospheric and hypersonic flight profile much like the X-15. The real show stopper on the 2-stage Shuttle was not ol' Dick Nixon's parsimony and hatred for Kennedy-Johnson lead space programs. It was that no one built something with the performance of the X-15 (and with comparable reentry thermal requirements) that was several times heavier than the biggest aircraft ever built.
When they built the current Shuttle, they went with solid rocket boosters with not nearly a typical first stage performance, but they had to go with a disposable tank and with really stressed rocket engines to essentially make a single-stage to orbit, with the SRB's giving the rocket thrust to lift the thing off the ground. Even so, those SRB's are a larger mass fraction than you think because they are denser than liquid fuel rockets, and they take the Shuttle well past the flight envelope of that plane we are talking about.
When you are talking single-stage air-launch, you are really talking single-stage to orbit with a little help from the air launch, and you have to achieve 80 percent fuel mass fraction with a vehicle that has to be carried on an airplane.
If you are interested in the space-launch problem check out http://www.ghg.net/redflame/launch.htm. If you are interested in a much more practical solution see
http://www.fourmilab.ch/documents/rocketaday.ht
it's not about b52's.
This is about C17's and other heavy transports.
the b52 pegasus launches are old news
And for all Galaxy and Starlifters carry troops around you'll find that across their lives they've done far more disaster relief around the world.
'There is a Light that never goes out.'
Actualy there were about 120 C5A's built. I think 2 have been destroyed in operations over the years.
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Can't remember if the energy saved from the gain in altitude was enough to offset the other problems.