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Rockets of Doom From Carmack And Friends
Clark Lindsey writes: "John Carmack of
Id Software fame has gotten deep
into serious amateur rocketry. His Armadillo Aerospace
web site gives regular status reports on the efforts of his team of mostly volunteers in building very
low cost VTVL (Vertical Takeoff, Vertical Landing) hydrogen
peroxide rocket vehicles. Last week he gave an impressive
presentation at the Space Access Society meeting
with a description of the progress made in their incremental
development of remotely controlled vehicles that will eventually
lead to a manned (suborbital) version."
The Space Access Society is worth checking out, anyhow, if you're interested in leaving earth without a NASA ticket -- their mission is to promote "to promote radically cheaper access to space, ASAP." The Armadillo Aerospace site also has one of the coolest-looking Linux machines I've seen yet, but there's no accounting for taste.
You can see parts of Carmac's Ferraris on this picture! http://www.armadilloaerospace.com/Vtvl2.jpg
The big deal about using hydrogen peroxide as fuel is the simplicity of the engine design. All you have to do is run the peroxide (which is, btw, far, far more concentrated than what you buy at the drugstore) over a platinum mesh, and there is a catalyzed reaction and the stuff goes off.
Combine that with a simple, pressurized fuel tank instead of turbopumps, and you have a rocket engine with the minimum of moving parts. Perfect for a technology demonstrator that's more about the other parts of the system than the rocket itself.
The late, lamented Beal Aerospace was building a big booster rocket by scaling up this technology, and with a fair degree of success. (Then NASA stomped them flat by announcing a "civilian space launch initiative" that would have amounted to subsidizing Beal's competitors. Beal closed up shop.) Read the Space Access Society's pages to see what they think of NASA these days.
For more fun with peroxide rockets, see here.
Jon Acheson
All opinions expressed herein are my own, and not those of my employers, who are appalled.
By itself a mono propellant has a horrendous ISP, which is a measure of the effeciency of a rocket motor. It does however make a good oxidiser for Hybrid motors, which have a liquid oxidiser and solid fuel in the chamber, plastic is a good fuel.
"Because we are not employing at entry level, offshoring will kill our industry stone dead."
ID did *all* of the commander keens, apogee was *only* the publisher.
Carmack, Romero and a third gentleman whose name i don't recall created ID so as to be able to sell publishing rights of Keen to apogee.
Keen was created to demonstrate a cool new scrolling algorithm which Carmack had come up with...
They did the game in 3 months on their spare time.
...
Yes, I know I ramble and my spelling isn't quite up to scratch. If you wish to complain,
I don't have an orbital timeframe. There are too many things I need to learn before I can make a credible estimate.
The timeframe I do have is:
Year 1: work out all the kinks in the VTVL demonstrator.
Year 2: manned rocket ships and ballistic flight, but still rather low altitudes.
Year 3: space (100km) shots, both unmanned and manned
John Carmack
The throttle is manual, but attitude control is computer managed. The joystick input gives a target angle, and the computer deals with rates and pulses to try and get it there. Manual control of a differentially throttled vehicle is extremely difficult (the simulator allows you to try).
CG/CP is irrelevent for this vehicle, because it isn't designed to go fast enough that aerodynamics are a factor.
Four fixed position engines can give full 3 axis control if you are tricky about it. Opposite pairs of engines are canted a few degrees so that one pair of engines gives a slight positive roll, and the other pair of engines gives a slight negative roll. This does mean that there is a cross couple for every pitch or yaw adjustment, but with an order of magnitude difference between them, it is easy to correct out.
The difficulty of guidance and control is overrated.
John Carmack
I should ammend myself, and say that the difficulty AT LOW SPEEDS is not that bad. Removing aerodynamic factors simplifies things a lot.
Doing something like hypersonic kinetic kill missile guidance still sounds, uh, non-trivial.
John Carmack
I should mention that really, all of this work can be traced back to slashdot.
Until a year and a half ago, I hadn't thought about space and (real) rockets since I was a kid.
I started reading slashdot for the open source coverage, but the occasional space story and the comments on them led me to the CATS prize and the other things going on in the space community.
I spent a year learning the engineering aspects and funding a few things that I considered interesting (JP Aerospace, SORAC, Space Frontier Foundation, and XCOR), and the last six months actually doing something myself.
I was sort of planning on submitting an article about the whole process at some point, but it looks like I got preempted (and our site is slashdotted)...
John Carmack
Have a look at the water rocket page and a very nice page about the rocket equations. There is also a good page on howstuffworks
By posting news associated with Doom, Quake, and others, you are encouraging young readers of this site to take railguns and rocket launchers to school and shoot their classmates. That is a truly awful thing and I don't see how any of you can live with that on your conscience... And that's just sick, so you should all be ashamed.
I have to laugh everytime I read about the problems with guns in school. I shot on the school rifle team for 4 years. Thats right I shot a gun every day for four years in a school building. Yup in a school building, and before you jump on that its called a bullet trap it will safely stop a 30 caliber round. Right in the basement of the school Autitorium. The one thing I always found interesting is how all the other team sports seem to end up having a fight with the other team at some point during the year. But not the rifle teams.
Maybe if John is successful we can launch all the liberals to another planet so that the can run themselves and there socialist ideas in to the ground somewhere else...
Remember Peace through superior firepower does work!
I knew Carmack must have been scraping the bottom of the barrel for new ideas when he announced Doom III, but this is way too close to Commander Keen for my liking. Does he wear his big brother's football helmet while launching these rockets too?
(btw: was it Apogee or id (or both) that did the original Commander Keen?)
Yup, I'd imagine Carmack has a thing or two to teach those amateurs at NASA. Bet they'd be real interested in the portable rocket launcher, for instance. And I bet the US Army would be thrilled to lay their hands on a BFG2K.
^]:wq!^M
1. Providing 3-axis stability, given a limited number of vertical (or tangential) thrust vectors, as opposed to an almost unlimited number of external de-stabilizing forces.
2. CP changes caused by the expulsion of fuel
3. Difficulty in calibrating throttle response combined with slow control input/response cycles (made that much worse by the inherent latency of telemetry transmission)
I'd guess, that their ultimate intent is to provide some form of on-board stabilization system, with off-board control primarily manipulating the vehicles post-balance trajectory, while the vehicle itself controls pitch,roll, and yaw through some form of accelerometer feedback mechanism. The mathematics necessary for manipulating all those angular differentials ought to be enough to give even John a trial or three. Non-trivial.
The design of the vehicle itself should be interesting as well, since ideally, you'd want all the motors in the same plane with the CP - which unfortunately causes a wider sectional, and increases drag, thus increasing the fuel and power requirements.
Sounds like something that would be a lot of fun to work on though. I wonder who they have in mind as the ultimate first pilot? Flying this thing ought to make tooling up 635 in rush hour look like sleeping :)
The German U-791's used Hydrogen Peroxide for fuel, and I wonder if NASA altogether dropped this idea. Would be interesting to see someone power a car on peroxide and test the environmental hazards involved.
Well hopefully Carmack can get it up and going soon, maybe he can get people like Tito to give him 20 million to send them to space.
countdown continues
360 degrees of Karma
Somebody should stop him, we don't need anyone associated with Doom *anywhere* near our lunar or martian bases...
Certainly, Carmack's thoughts on timing for moderatly inexpensive (I think his "expense" standards are broken, but whatever) spaceflight are optomistic, but if the inventor of doom says I get weightlessness, I expect weightlessness.
I think the real problem, however, is in carmack's approach - he's aiming for a suborbital manned shot first, before he goes for a true orbit - whereas the prospace people (they have a good update here are aiming direct for a full orbital launch in the next 5-7 years at costs in the affordable range for well off people (as long as you don't get hit with the AMT as opposed to the incredibly rich (where it is now)
I'm the best IRC client ever.
I'd bet money his interest stems from a desire to shoot all remaining copies of "Daikatana" out into space, so future generations will have no record of the game's existence.
However, I don't think that's really the kind of impression we want to give aliens of Earth.