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Brian Walker (aka Rocket Guy) Fires Back
1) Exotic Fuels
by cybrpnk2
Amateur rockets don't get to space or orbit because they're generally limited to low specific impulse solid fuels. Is there much of a gain in specific impulse to be obtained by further research into hybrid (ie, plastic/nitrous oxide) propellants? How about exotic chemicals (buckyballs, multi-atomic nitrogen, fluorine for example) - any route for amateur utilization of these?
Brian Walker / Rocket Guy: I am using 90% H2o2 because using it as a monopropellant is the safest method of propulsion for my particular rocket. There is no chance of a catastrophic explosion or fire. This alone eliminates about one half of all standard problems that are encountered for any rocket flight.
2) operational testing?
by Nehemiah S
What kind of testing have you done for your design(s)? Wind tunnel tests, computational fluid dynamics, flying scale models, etc? I've also noticed that your design has changed considerably since the first time you were featured on Slashdot, and as an aerospace engineer myself it would be interesting to know what your design criteria were and how you arrived at them.
RG: My design has changed because I do not profess to be an aeronautical engineer of any sort, and as I have proceeded, I have allowed myself to make the necessary changes resulting in a better design. A number of people have a called me on several design concerns, and I listened. As for wind tunnel tests and the like, no. The rocket is near perfect in its shape, and for what I require it to do (go up and down in a relatively stable manner), it is fine.
3) Cowboy hat?
by micromoog
In case something goes wrong, are you planning to take with you a large ten-gallon cowboy hat to wave around on reentry?
RG: No, I'll be wearing a space suit, and a cowboy hat would not be a wise fashion accessory.
4) What about John Carmack's project?
by tswinzig
Have you discussed rocketry with John Carmack and his friends at Armadillo Aerospace? They plan to eventually fly a manned rocket as well.
RG: Met John in Arizona back in April. I have a great deal of respect and admiration for him. We are opposites -- he is very methodical and is a computer genius. I am not. Between my Dyslexia and ADHD, it was a miracle that I made it through school at all. I simply don't have the same mental drive as Mr. Carmack does, so I do things the way that work best for me, and 18 licensed toys have served me well.
5) Funding vs technology
by Andy_R
How much of your project requires technological innovation on your part, and how much is just a question of raising funding to duplicate existing technology that governments have already researched?
RG: 90% of what I am doing is the result of simple refinement from what has been done, time and again, over the past 50 years or so. Remember, I am not trying to orbit the earth. It is a simple elevator ride for 20 minutes.
6) Rocket Industry Efficiency
by Local Loop
Which parts or subsystems did you make, or have made, yourself, that you wish could have been purchased off the shelf for a reasonable price?
Which parts or subsystems do you think are candidates for standardization in the coming personal rocket industry?
RG: I have purchased (and will purchase) a number of components like parachutes, valves and fluid handling components, and the like. There are a great deal of parts that can be used right-off-the-shelf. As for which parts could become standardized for personal rocketry, I am not really in a position to know.
7) What's Next.
by DA_MAN_DA_MYTH
Say you are successful, and I hope you are. What's next? Do you try it again only higher? Also any plans of donating your rocket to the Smithsonian? This would definitely be considered Air & Space history and be worthy for all to view. Or on the other hand after are you looking for monetary gain? Something like pay 12 bucks to see Rocket guy's Rocket?
RG: I want to move on to a commercial launch operation which would allow a "for profit" venture to begin producing money for future development funds. The first step is "Rocket Skydiving" -- simple, catapult launched giant water rockets that can take a load of skydivers to 15,000 feet in under a minute. This would be safer than airplanes. As time progressed, we would introduce bigger and higher flying rockets, which would eventually allow non-skydivers access to 80-100 thousand foot high flights in small winged return vehicles with pilots. I would be happy to donate my capsule to Smithsonian.
8) Engine Work? by Anonymous Coward
Seems like you've done lots of mockups and landscaping, but I haven't seen any work on the actual engine (other than a single picture of it).
Having seen all the trouble with catalyst packs and such that other projects have had, how come you havn't done any test firings yet?
Have you even tested your pneumatic launcher?
RG: My facilities here are big, and I have had to continue to grow and improve things. "Landscaping" here has been minimal, and for the control of dust more than anything else (the Oregon High Desert is a dusty place). I have 15 rocket motors currently, one 2500 pound thrust motor, 6, 135 pound thrust motors (for capsule separation from fuel tank), and 8, 55 pound thrust motors (for capsule stability/guidance).
I don't know what is being referenced by "all the trouble with catalyst packs..." Peroxide reaction engines have been around for years, and follow specific scientific formulas. Some people are trying to make changes to get higher thrust, etc. As for the launcher, yes, it works perfectly. I have done the tests to demonstrate the amount of "push" it can develop. At 40 psi, it delivers 2000 pounds of push, and when the launch sleeves have cleared the launch tubes, there is only about an 8% loss of volume. As for a full test, there is a catch 22. In order to fully test the launching of an 1100 pound payload, I need to have a fully recoverable system on board, or I will destroy whatever is launched. I am in no hurry to do this test, and will do so when I am ready.
9) future of private industry space travel
by crystalplague
I, like a lot of people, are quite skeptical about the success of your project. However, let us assume that you have launched yourself, everything went perfectly, and you are resting safely back on earth.
What do you think this will do to the future of space travel? Do you think this will set a precedent for the private industry to get involved in space travel?
RG: Regardless of people's skepticism, I am pursuing what is (and has been my dream) for my own purposes. I appreciate the importance that so many other's have placed on this effort, but I would still do it if I was alone and no one was watching. However, due to the number of people who have made comments, I do expect my experience to encourage more private participation in the field of private space industry.
10) Had to be asked...
by Dirk Pitt
How does it feel to be the only person in history preselected for the Darwin Award nominations?
RG: I do not recognize any such nomination. To my understanding, the recipients of past Darwin Awards have been stupid people doing stupid things. My project is not a candidate for such. I am not doing this because i am bored and looking for fame and fortune. On launch day, if I've any inkling that I might not survive, I simply won't go.
11) Legal issues? by crow
Have you ran into any legal issues with your rocketry? Have the government had any significant impact (pro or con)?
RG I recently met with the FAA in DC, and they are very supportive, and want to be in a position of actually being able to issue me a launch license. They have been following my efforts for the past several years, and offered to be of any assistance I need to do things legally. I was very impressed and excited by just how receptive and supportive they were.
You what?! The parachutists will be dead, no questions. That is NOT survivable. Let's do the sums...
A catapult has no energy input once the projectile has left it. So if he wants to get to 15k feet, the projectile will need to leave the launcher at approximately 300m/s, ie. over 1000 km/h (from Newton, v^2 = 2*a*s, where s is 15,000 * 0.3 to give distance in m, and a is 9.8m for 1G).
Say the catapult is in contact with the projectile for 2s (for the sake of argument) and giving a smooth acceleration. That is probably way too high - planes launched off an aircraft carrier take less than 2s to leave the deck - but anyway. Then the acceleration is 150m/s/s (if the accel wasn't smooth, it could even peak higher than that).
That means that your parachutists are experiencing over 15G on takeoff. Which is well beyond the point at which every human (even top jet pilots) black out. So although the parachutists may make it to the top of the ride, they'll be unconscious and in no fit state to appreciate it! And since they'll be unable to pull their ripcords, they'll plummet to the ground and die.
Personally I think this guy should learn more fundamental physics, like basic Newtonian mechanics.
Grab.
The leading theory on what caused the explosion of the Kursk is the H2O2 propellant in a torpedo (NOT a warhead!)
(Here's another link)
...and another.
It was highly concentrated H2O2 that did in the Kursk. Nasty stuff.
Just thought I'd mention it.
"A microprocessor... is a terrible thing to waste." --
GeneralEmergency
Assuming constant acceleration, that'd be almost 3 Gs for sixty seconds. Fairly uncomfortable for the average joe.
-- Minds are like parachutes... they work best when open.
I just did a few calculations, and unless my usage of math is way off, travelling a distance of 15,000 feet in 60 seconds corresponds to an average speed of 250 ft/s which should be about 170 mph. I haven't calculated the G forces yet, but it sounds like no one on that water rocket would be able to jump out much less live after the ride. I do recognize that the mortality rate depends more on the accleration than the speed, but for now I'm assuming an impulse.
I don't practice what I preach because I'm not the kind of person that I'm preaching to.
Erm, it's possible to build a plane which is fundamentally stable. Anyone who's built a paper plane can show that But it is NOT possible to build a rocket that's fundamentally stable. A rocket is fundamentally UNSTABLE, and what keeps it stable is a complicated control system. That control system requires a whole lot of maths to get it right.
As long as you're in the atmosphere, it's trivial to build a stable rocket (just put fins near the back; check Estes' model rocket building guide for the detailed CP/CM explanation).
Outside the atmosphere (above a few tens of kilometres), it still doesn't take more than second-year engineering. You have a device to measure your angle off the vertical (be it a gyro, laser gyro, or a horizon-sensing camera), and you have a classic feedback control system that tries to make that angle zero.
Two op-amps and 50 cents worth of parts and you have your control system. The trick is making sure it's damped enough not to destabilize itself, but that's not horribly difficult either.
In summary, as long as you're not trying to do anything complicated, "Rocket Science" isn't as hard as you're painting it.
I really don't want to sound insulting, but being a model rocket hobbyist alone does not qualify you as a rocket scientist except in the most basic sense (if you're also an engineer, my apologies). Contrary to your experience, building a stable rocket frame capable of lifting more than 100 pounds is not only not easy, it's never been done. One of the things you're not dealing with is liquid fuel. To find out how hard it is to stabilize that, do this experiment (which I've done several times). Build a 6 foot frame about 2 inches in diameter. Put as much engine on the tail as you wish, and put an eight ounce weight in the nosecone. make the center two feet of the rocket a plastic tank, and half-fill it with water. Then launch. If your rocket gets more than twenty feet off the ground before it falls 20 degrees off launch vector, you can count yourself one heck of a designer (and I'd love to see your tank design). The other thing you're not used to handling is fragile airframes. A cardboard tube doesn't seem like much, but if you want to try building a rocket where the power-to-stress ratios are the same as a full size launch vehicle, build your next rocket out of drinking straws and construction paper. Also, keep in mind that a model rocket turning twenty degrees off its flight vector will fly in the wrong direction, but a full size rocket doing the same thing will generally collapse from the shear force. This is what makes the ability to design a complex guidance system so difficult. He makes no mention of his methods, but someone who does not have any engineering experience cannot typically design a functional gyrobalancing guidance system. Hell, people who are rocket scientists work on these things for years, and most guidance systems are designed for specific frames, so it's not very easy to "borrow" someone else's design for your own frame.
I wish him all the luck in the world, but not calling in some engineering expertise for review is asking for trouble.
Virg
You don't need a flight "plan" to fly up, drop parachuters and fly back, and most certainly any pilot who does such trips has a schedule with the local field, and other jump clubs already. You do need a 'plan' as any pilot requires knowledge of everything pertaining to the flight, but so would any rocket launch.
:) And rockets are directionially challenged, they usually only go straight up.. great if your airspace is only ever for jumping, but these days victor airways are dissapearing and people are flying over everything that isn't TFR'd.
Flight "plans" are only required for Instrument flights, and VFR pilots can file, but not necessarily required.
You can get your sweet bajeezus that any rocket launch will require flight planning, imagine shooting up 15,000 feet and plastering yourself into a 747 flying overhead or what a single seagull can do to your aircraft.. atleast with an airplane, you can dodge that stuff
Aircraft MUST be well maintained, but so would any rocket, even MORESO. Aircraft easily get a million miles on them in a lifetime, you figure between each engine rebuild you get roughly 250k to 300k "miles" on them, and most trainers (ie, planes flown by INEXPERIENCED pilots) are already on there 3rd/4th rebuilt, so they too have last through alot of abuse and still kept there pilot alive and sent someone out into the wild blue yonder.
When flying, you will most certainly notice non maintained runways, infact you will probably land on a few "doosies" and grass strips, that are simply mowed down hills.
And with an airplane, if things go bad, an AIRPLANE FLIES!!! Pilots are TRAINED to find the best GLIDE RATIO.. and you figure 10 feet forward for one foot of altitude loss and 15,000 feet with catastrophic engine failure you have more then enough altitude to glide back to the very airport you took off from or find another.. in a rocket you certainly hope you can get out before those 3GS of falling back to earth hopelessly pin you inside.
Aircraft are safe, because your trained to fly them safely. People don't jump from leerjets or 747's, they jump from aircraft with a proven track record.
I know i can rent a jump plane for $150.00 an hour wet (fueled) and take 6 jumpers up.. i would only have to charge $25.00 a head to break even.. i can't imagin a rocket that cost effective.
If anything large gliders, towed behind a piloted aircraft would be the safest.. no motors, excellent glide ratio back to earth, quiet jumping, and re-useable without re-fuelling or rebuilding a motor.
"Think about it... better than 90% of the launch vehicle's mass is fuel and oxidizer."
Not true in this instance. This sucker is a monopropellant rocket-- it uses Hydrogen Peroxide which won't blow up. No volatile chemicals either-- it just reacts with stainless steel producing steam.
The best part is that you can throttle it up or down and stop the engine completely-- something that's very hard to do with solid rocket engines. I hope that he makes it and shows the world the capability that this rather simple technology can provide. Hell, I'd love to power my minivan on the stuff and it can be extracted from seawater!
Best of luck I say!
> ...missiles using similar liquid fuel using only aerodynamic surfaces and relatively simply gyroscopic guidance systems.
Both of your examples are not capable of getting high enough for this guy.
> None of this technology is new or complex by modern standards.
Nor is it very useful for this guy. The guidance systems used by V-2 rockets were (unsurprisingly) designed to stabilize V-2s, and as I said before, simply lifting a design from a different frame usually doesn't work.
> I don't believe I suggested making a full size rocket out of cardboard tubes either I'm fully aware of the fact that as the scale increases so do the stresses on the airframe.
The example I provided was more to illustrate that one of the major problems with big-scale rockets is that the guidance system can't be "good", it has to be "great" because the stress forces from pivoting just a tiny bit out of flight line are sufficient to demolish all but the heaviest designs, something model rockets simply don't suffer from.
> Try taking your tube - filling it with a sponge like material and then adding the water. Not such a great design problem when you think about it.
This one is actually on the books, because a few builders thought that a saturated medium would make for low-splash fuel tanks (when it was proposed, sloshing fuel was a major guidance problem, as most rockets at that time burned kerosene). However, the design failed miserably, for two reasons. First, it was very difficult to get the fuel out of the medium when you needed it to burn (something my experiment doesn't address, but that a liquid-fueled engine must do). Second, When the medium was subjected to the G-forces of launch, it would simply squash down to the bottom of the tank, which caused the top portion of the tank to be only liquid (back to the sloshing fuel problem) and putting severe stress on the bottom of the tank (which caused more than one tank rupture with resultant kaboom). So, it's a good idea, but I must send you back to the drawing board.
Virg
Sigh...
I've met Brian, and he's legit. He DOES do his homework. When he claims not to know much about engineering, he's really being modest. Anything he doesn't understand, he learns. Anything he thinks he needs to make his project successful, he does. Example: Cosmonaut Training.
I have a friend who helps him from time to time, and my friend is a veteran of aerospace design, from his father being an aircraft mechanic, to him working for companies like Aerovironment, and working on experimental NASA craft.
I have also personally seen Brian's equipment, designs, engines, and facilities, and am quite confident in his ability to make his project succeed.
"Alcohol, Tobacco, Firearms, and Explosives" should be a convenience store, not a government agency.