DARPA: You didn't think we could make a Mach 6 spaceplane, so let us have this MACH TEN job In this post-Space Shuttle world, it often seems that the dream of a spacecraft which could reach orbit without expensively throwing most of itself away is receding rather than drawing closer. Last time DARPA went for a spaceplane - the X-30 SSTO concept of 1984 Sure, there's the tiny X-37B "space warplane", carrying out …
Not a rail gun per se, but a magnetic launcher (aka 'coilgun') has potential. These are the key factors:
1) The advantages are in potential launch frequency and cost, which is mostly related to fuel and not having to throw away hardware.
2) don't try to do the entire launch package from the railgun, use it as the first stage replacement.
3) without a lightweight heat shield, you are limited in the maximum speed until you get most of the way out of the atmosphere to avoid burning up. But even getting to mach 5 (3800 mph, 1.7km/s) saves about half the fuel. It's been said that 50% of the fuel is used getting to the first 100 feet off the launch pad.
4) if you want humans on board, it's going to be a very long coilgun. I ran similar numbers a couple of months ago - at 10G to reach 5km/s would require a 12.5 km coilgun and 50 seconds. That's beyond what most humans can take, but would be fine for most cargo. I'm too lazy to redo the numbers for 5G and 2km/s but using thumbnail math, 5G to 2.5km/s would also be 12.5 km but 100 seconds?
5) don't forget the mass and handling of the 'carriage' - the thing that the vehicle rides on going up the launcher - you don't want to launch that
The bottom line is, if you look at the coil gun as a cost saving system (long term), it could work. And Ecuador actually does have a space program, so there's an opportunity for someone to work out a deal. Having such a launch system right on the Equator is certainly advantageous. I would think that such a launch system would cost a few $billion.
Maybe "it's been said", but that is crazy on the face of it. Think how fast the typical rocket is moving when it reaches the 100 foot mark, and explain why you would believe such a wild assertion when you're only traveling a fraction of the speed you need to reach after only 100 feet. If this was the case, rather than lift all that extra fuel off the pad for only 100 feet, they'd have the rocket connected with a breakaway hose to supply it and make the first stage half as large or use that reduced weight to massively increase the lifting capacity!
Disclaimer: I'm not a rocket scientist, but I'm able to recognize off-by-at-least-a-factor-of-ten errors in logic when I see them.
MechJeb's attitude hold makes achieving orbit much easier, but the fuel margins are so tight you can use space planes for hauling kerbals and not a lot else.
That said, taking one from the runway, refuelling at an orbiting station and then landing back* on the runway is seriously satisfying.
* Or, you know, crashing on the runway.
SSTO Spaceplanes aren't too hard to get into orbit in KSP (hint: smaller planes are vastly easier to use)... but their payload fraction is so small that they're not much use for anything other than ferrying crew. They don't scale very well, either. It is one of the ways in which KSP is rather like real life, in fact.
We shall soon see.. the next Falcon 9 Launch is the full size stack (60% larger than the current dragon launchers) it's using the octoweb engine configuration and it'll attempt a soft landing over water.. (which may or may not work depending on the radars ability to see water, as it's designed for land)
This is the first step in combining grasshopper into a real rocket. There are still many things that could go awry in just the rocket nevermind the soft landing. But its an awesome system nonetheless.
It's currently sat on the launch pad at Vandenburg afb, and is due to launch very soon (in days).
Agreed.
"So it might seem to many observers that the dream of re-usable, affordable access to space for the human race remains as far off as ever."
Seems an odd statement to make , esp. as it follows the paragraph about the grasshopper, which to me seems a great step forward towards reusability.
1) Can we use it to kill people, preferably enemies (i.e. any foreigner)?
2) Will it cost at least $1 billion for each person we kill with it?
3) Will the cost be at least 100 times the amount of campaign contributions needed to get it approved?
4) Could the money be better spent on more socially useful projects?
If the answers to the above are all YES then go ahead and build it.
...I think I'm getting a wee bit cynical
>You'd have canned the whole CERN thing too, wouldn't you
I don't see the comparison between DARPA and CERN
DARPA is military and top secret for the US only
CERN is multinational, all discoveries are open to all.
<goes back to my Higgs field ant-gravity space-plane research>
the US did cancel it's very own "CERN thing." it was the SSC in Waxahachee. 40TeV collider vs 14TeV for the LHC. could have been run at 1/3 power back in the late nineties and grabbed the Higgs then. all the talent and money that went to CERN could have stayed in the US for a few billion more. what will 10-15 more years of research into actually knowing what mass and inertia are, rather than just describing them, bring?
the US government broke an unwritten agreement with the scientists when they canned that particular project. the agreement was that scientists would work like dogs for short money and the government would pay those salaries and pick up the cost of equipment. this type of thinking has done as much to cripple the US economy as sending all the manufacturing jobs overseas.
> How much in the world of medicine has its roots in military R&D do you think?
Quite a lot I suspect, particularly the techniques dealing with the effects of injuries caused by all those clever gadgets developed by DARPA and the rest of the world's Merchants of Death (TM)
"How much in the world of medicine has its roots in military R&D do you think"
Actually plenty, especially in the world of trauma medicine, those skills are honed and refined on the battle field..
Even vaccinations were often first tested with the military.
Then we have the exciting limb replacement field of research, and I am sure that the fancy ultrasonic bleed stopper thingy they are working on will be a life saver for paramedics once they get it down to commercial cost.
And I thought those skills where developed on the streets of our big cities, I understand that the US military train a lot of there surgeons by getting them to work in some the Big West cost hospitals (I suppose that is one advantage of america's policies on guns - well trained trauma surgeons).
And here in the UK, a lot of our trauma care practises were developed in Northern Ireland by civilian hospitals.
"And I thought those skills where developed on the streets of our big cities, I understand that the US military train a lot of there surgeons by getting them to work in some the Big West cost hospitals (I suppose that is one advantage of america's policies on guns - well trained trauma surgeons)."
Actually quite a few of those techniques were developed on the streets of Belfast during "The Troubles," as the UK liked to call the low key civil war it fought for 38 years.
"How much in the world of medicine has its roots in military R&D do you think?"
Reconstructive Plastic Surgery
The military R&D contribution to Reconstructive Plastic Surgery consisted entirely in supplying horribly injured patients for surgeons to work on in civilian hospitals. So their contribution was not dissimilar to that made by Burke and Hare in an earlier era.
"How much in the world of medicine has its roots in military R&D do you think?"
Off the top of my head.
Antibiotics WWII. Historically infection has killed many more wounded that the original injuries. They only started to become available to civilians after WWII.
Surgical methods to operate on beating hearts (shrapnel wounds in WWII)
Reconstructive surgery (Look up "The Guinea Pig Club," or watch parts of the film "Battle of Britain.")
Improved amputation, antisepsis and prosthesis development. Every war.
Use of cyanoacrylates to glue wounds together without stitches and reduce trauma. Vietnam.
Direct injection to the heart through the breastbone. Vietnam.
"Smart stretcher" technology to give better monitoring of patient conditions with fewer qualified staff..
And IIRC developing ways to wash out living cells from things organs leaving a scaffold to act as a template for a patients own "precursor" cells to populate, eliminating rejection issues.
That's just my 30secs of thought.
You might be surprised. It's focused but significant
I always find it funny how military R&D is promoted as a positive thing because it has helped non military people......
Think about this for a few seconds;
Broad estimate, 150 million people killed in wars last century, and far more wounded, these wounded are the reason to get better at medicine, but how about, don't have war? all those people, all that lost potential, what could they have done? what if all of the people who lost limbs in the war didn't lose limbs? isn't prevention better than cure? is burning a house down a positive thing as it helps us learn how to put out fires?
Yes, absolutely, through need, we learned so much more - but that's because so many died and suffered, imagine if we didn't pile the billions into killing people ($700bn a year for defence in the US), imagine what we could do instead, the education we could pay for, the infrastructure we could build - the rovers, the rockets - imagine if we stopped thinking "what can this kill" and started thinking "what could this tell us", yes war gives us developments, some of which have good spinoffs - so why not just look at the spinoffs.
"1) Can we use it to kill people, preferably enemies (i.e. any foreigner)?"
True.
2) Will it cost at least $1 billion for each person we kill with it?
False.
The "Tactical Technology Office," of which this is part, may be a $Bn operation but individual DARPA projects are much smaller, 10s-100s of $m. The goal is High risk/High return. In fact very high risk.
3) Will the cost be at least 100 times the amount of campaign contributions needed to get it approved?
Wrong. This is more like an old Hollywood B picture operation. Fast turnaround, long shots, minimal costs.
4) Could the money be better spent on more socially useful projects?"
It's the DoD. They employ millions of staff and spend Trillions of $.
What's not "socially useful" about that?
Please stop hugging the tree and return to your lentils and brown rice.
Building a nuke is easy. Building rockets is hard. Building space planes is dark fucking magic.
Seriously. "North Korea built it's own nukes." Annnnnnnnnnnd?
Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.) Even a basic implosion device is simple, assuming you're okay with it being the size of a house. (The chances that these are miniaturized enough to fit on a missile are slim to none.)
"Possible feasible and affordable" take a back seat to "comprehensible." An iPad is "possible, feasible and affordable." Yet, if you weren't allowed to do commerce with the rest of the world to buy one and didn't have knowledge of the past 50 years of intermediate technologies, that iPad simply isn't "comprehensible." It takes massive amounts of infrastructure, engineering and high-tech capability to make an ipad.
It takes some C4, a couple slabs of U-235 rich(ish) uranium and some scrap metal to make a nuke.
Wake me when North Korea can make an iPad using technologies it didn't have to steal. Then I'll believe that there is a chance of anyone but DARPA developing a SSTO spaceplane within our grandchildren's lifetimes.
> Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.)
Ok, that means you need U235. Do you know of an easy way to get that?
Do you need an initiator for your design? What will you make it of, and how large is it?
What is your critical mass? What amount of explosive do you need in the gun to avoid a squib explosion? Is there any danger of the explosive shattering the uranium that it is propelling?
@Scott Wheeler, whilst this isnt a step by step DIY guide to making a nuke in your shed theres some interesting insights into building a plutonium implosion bomb here:
http://wlstorage.net/file/penney-report.pdf
Although I would dock them points for using a polonium-beryllium initiator (PoBe) a plutonium-beryllium initiator (PuBe) has much more scope for mirth and giggles.
I believe that building a nuclear bomb is at least as difficult as building a space plane. I read somewhere that, even if you have the plans, you can still fail your design if you don't have someone with experience in the project. Blowing up a charge of plutonium is easy, making a proper nuclear blast is one of the highest-level techs there is aside from rocket science.
And that's a good thing too, otherwise there would be much too many madmen with a twitchy finger on a launch button.
Nuclear Bombs are neither Rocket Science, nor Brain Surgery.
That is why those two maintain a duopoly in that particular cliche market. Building a working nuclear bomb is very very hard, no doubt about it, but if a small bunch of septics could build one in the 1950's, with no computers to speak of, and with no 'prior art' then it is little more than a matter of effort these days. (And access to fissile material)
Building an implosion type nuke is about as hard as a space plane. Building a gun type nuke is child's play.
An implosion type nuke is what you need to put on a ballistic missile. It also can theoretically scale up to at least a hundred megatons. A gun-type nuke is something you'd be lucky to get a handful of kilotons out of.
They are completely different devices.
>Basic nukes aren't hard. They require zero engineering experience (for a gun-type nuke.)
If I remember correctly, New Scientist published a spoof article (around 1982 +/- 2 years) which suggested you could build one in a terraced house if you didn't mind what the neighbours would say about you using an old pram to ferry raw ingredients around while all your hair was falling out and the walls started dimly glowing in the dark....
(If anyone can point me to this article, I'd love to see it again. Yes, I have looked for it before now ...)
1) I live in Alberta. Strikes me that a good chunk of the world's supply can be dug out of the ground not far from here. It doesn't take much to find a mining company with some rights to prospect up there and piles of equipment either. IIRC NK has deposits of it's own, and they can buy from the Chinese.
2) You don't need a neutron initiator for a gun-type nuke. They make it more efficient, but if you wanted efficient (as opposed to a self-spreading dirty bomb that makes a small crater) you wouldn't be using a gun-type nuke in the first place.
3) IIRC, it's about 20 lbs of Uranium at 80% for the design I know best. Yes, there are all sorts of risks to the design for things like squib explosion and shattering the bullet, but to remember that you don't have to ram the pieces together very large. You need to get subcritical mass A into subcritical mass B such that they go supercritical all on their lonesome and they make a boom.
If you really wanted to point to the difficulty of making a nuke you'd talk about refining the Uranium. Going from raw ore to even 20% enriched U238 (let alone the 80% needed for most primitive gun-type designs) borders on dark magic. You're basically talking about needing a gas centrifuge. How - exactly - one goes about that without killing everyone from Uranium hexafluoride poisoning - let along the possibility of inhaling some of the radioactive fun stuff - I have only the barest inklings of a clue.
Gas centrifuges are fair simple. Gas centrifuges that have to deal with something that corrosive and can't be allowed to leak even the smallest amount at any stage due to the radioactive nature of the product? Crazy stuff, right there.
http://nuclearweaponarchive.org - nearly all you need to know about basic weapon design and construction, it's fairly easy to make a nuke. Weaponising it takes a bit more effort, harder still to get it to fit the pointy end of a missile. However it is not like you want it to come back and land for reuse once you've lit the blue touch paper.
Making a reusable & reliable rocket/space plane takes mathematics, engineering, physics, chemistry, materials science, electronics, computing etc. AND more political desire than for using these to make bombs.
A lesson from history -
“ All modern aircraft have four dimensions: span, length, height and politics. TSR-2 simply got the first three right. ”
— Sir Sydney Camm
Not applied science. Their job isn't to develop commercial products, it's to develop new technologies which are too expensive or where the payoff is too distant or too uncertain for commercial companies.
Which, effectively, is all technologies which can not be monetized in less than five years.
So I like DARPA.
One should however remember that their prime goal is military. The hypersonic aircraft they're researching aren't intended to shuttle businessmen from New York to London or cargo to the ISS, they're intended for rapid deployment of bombs and troops anywhere in the world.
Don't count out Skylon yet!
the pre-cooler works it is the primary new technology they needed..
They are funded right now, I am positive as soon as they get a working Sabre engine finished, they will get more backing...
And since they plan to sell them rather than run them, they don't need the capital to go all out and build a fleet, just get to the point buyers are confident!
I really hope the UK gov decides to fund it soon
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