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Pulse Jet Go-kart 96

An Anonymous Coward writes: "For those who liked the jet-engine beer cooler, here's another back-yard inventor from New Zealand who likes playing around with jets - he's not looking at the more common turbojet, but instead seeing how he can improve the long-neglected pulse-jet engine. For some background, see his homepage or just look at the go-kart he built to try out his jet." Pulse jets are an inefficient design that has been entirely superceded by other engines - but wow.
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Pulse Jet Go-kart

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  • by Anonymous Coward
    What? Can't he build a Battle Bot?
  • by Anonymous Coward
    I'm afraid you'll have to ask your parents about Santa Claus.
    Nah, just ask The Sun. [barricksinsurance.com] (Quick answer: "Yes, Virginia, there is a Santa Claus.")
  • by Anonymous Coward
    If you did anything vaguely related to jet provisioning, you'd know that the Allison 250 is just a _little_ more expensive. This guy is doing a low-budget backyard project.
  • by Anonymous Coward
    The first well known use of the pulse jet engine was with the V-1 used by Germany in World War II. They were fairly successful although they could be shot down. As far as being low tech, there is some evidence of a pulse jet being used in a classified US military program. People have seen in the sky pulse jet like contrails (instead of the solid contrails created by normal jets, add puffs to the contrail). These contrails are supposedly connected to a SR-71 replacement.
  • by Anonymous Coward
    If you follow his links a little bit you get to this page: http://aardvark.co.nz/pjet/turbinenuts.shtml My favorite has to be the MR-2 with 3 jets on it. At 80mph top it might not be the king of the road, but anyone coming to near its rear is going to end up with a melted frontend.
  • by Anonymous Coward
    Well yes, but Star Trek is not real. I'm afraid you'll have to ask your parents about Santa Claus.
  • by Anonymous Coward
    Hey, I'm posting for the first time in weeks to echo the praise that others have already expressed for this and the other ("Jet Powered Beer Cooler") article. Slashdot used to have fun and cool links like this every day, but has degenerated in the past year-and-a-half to the sad state it's in today, where 90% of articles are pointless Microsoft-bashing, lame "Ask Slashdot" product placements, and doomsday reports of layoffs and the stock-market. It would be great if Slashdot could regain some of its former innocent light-heartedness. I can't stand most of the crap here:
    • I know you guys hate Bill Gates, I don't need to hear about IIS bugs and .Net every fscking day! It's funny, this place is like a Microsoft news site now.
    • Save your anime reviews for AnimeFu, Rob. I was watching anime before you even knew how to spell it (actually, I sort of doubt you do now!) and if you think that crappy domestic dub releases rate as "news" among real otaku, you're even more out of it than we thought.
    • Jon Katz, please kill yourself! You're no more entertaining as "Mr Movie Review" than you were as "Mr Columbine." You ripped off the Slashdot community once by trying to sell a book with our insight, and no one who remembers that will ever read your articles again.
    • Michael, you fucking NAZI, I don't know how you ever got on Slashdot in the first place. Go on, mod down this post now, before anyone sees it!

    I prefer Slashdot's old style:

    • Lots of Linux, UNIX, and Mac stuff.
    • Very few Microsoft stories.
    • Insane, bizarre hacks -- often related to beer or video games.
    • Quickies. Frequent quickies.
    • OS/window manager/shell/CPU/architecture flamewars. C'mon, they were fun!
    • The yearly Xmas-list blowout
    • Decent polls.
    • Taco and Hemos posting more than once per week.
    • Et cetera.

    I know that you guys say you'll post whatever you like, but fun articles like this one are what made Slashdot a success. If the past year's change is indicative of things to come, I believe that I speak for many Slashdotters when I say that we'll take our hits elsewhere. If you're really just doing this site for yourselves, why even bother posting stories at all?

    -- The_Messenger

  • Posted by madcow15:

    It is quite obvious to me that you my friend are either in-bred, or were born without a fully functioning brain. New Zealand is actually not all sheep farms they are quite civalised and have a rugby team that would destroy any of your weak head gear wearing cotton-ball protected footballers that the your pathetic NFL could throw at them. Nice comment :(
  • Wired printed a pretty cool version of the rocket car story [wired.com] a while back. man i wish they'd put more articles like that in the mag again, it would be worth buying rather than browsing the web archive occasionally.
  • by drix ( 4602 ) on Sunday July 29, 2001 @09:10PM (#2184189) Homepage
    Roger that. Here's some more stuff you might be interested in:
    • No one is really sure what the bike's top speed is. McIntyre had a pair of Sheriffs radaring him at both ends of an airport runway, but their guns maxed out at 199mph :) He theorizes probably above 250mph, though (!)
    • My Dad knows Jay through business and is a fellow motorcycle enthusiast. One day my Dad & some friends were at The Rock Store, which is a small restaraunt/biker hangout on Mullholland Drive in the Hollywood Hills. Lo' and behold, Jay pulled up on his "jet bike" so of course everyone wanted to go take a peek. Jay starts talking about his trip over and about how some guy in his shiny new BMW pulled up extra close behind Jay so he could get a look at the bike. The thing is, the exhaust from Jay's bike started melting the front bumper off of the guy's car (Jet exahust = 1500+ degrees Fahrenheit)! Jay said he tried to warn the guy but he didn't get it and since they were parked at a red light he just had to sit there and melt the front end off this guy's car till it turned green :)
    • Manufacture's site [marineturbine.com]
    • NPR story about the bike [npr.org] (RealAudio). Cool because it has a phone interview with Jay, and you get to hear the thing starting up! Gives you a sort of "what hath God wrought" feeling when you realize someone's about to hop on that monster and drive it around :)

  • Don't mind them -- it's all part of the technically-arrogant too-serious-to-play faction that swoops down on any /. story about non-electronic hardware tinkering. You have to wonder how many of the snotty, cynical posts about the Darwin Award are coming from people who might themselves be eligible for one if they were imprudent enough to use simple power tools. (No, Dremels don't count as "power" tools.)

  • I agree that the article was good, but you don't
    know slashdot very well if your complaints are honest....

    I can't stand most of the crap here:

    What bothers me most is most of the "Dear God how
    did this website become so sucky" compaints. Too
    bad I can't just mark a box in the (*cough*,*cough*) preferences that would somehow filter those comments out.

    What's that, you say? You don't know what the
    preferences are? That's right, it's a way to filter
    out most of the topics that you don't like! Let's
    see if there's a way to exclude the stories that you can't stand!

    I know you guys hate Bill Gates, I don't need to hear about IIS bugs and .Net every fscking day! It's funny, this place is like a Microsoft news
    site now.

    Look! There is a topics category for this! You
    could exclude all microsoft news from your reading!

    Save your anime reviews for AnimeFu, Rob.

    Is there a checkbox for this category? Why yes,
    there is!

    What is the sound of one checkbox clicking, otaku?

    Jon Katz, please kill yourself! You're no more entertaining as "Mr Movie Review" than you were as "Mr Columbine." You ripped off the Slashdot community

    OK, Mr. High and Mighty AC: some phrases are funny,
    but "please kill yourself" just ain't. Thank goodness we aren't letting a person who can't figure out slashdot's preference system decide who lives and dies in this world.

    Oh, wait, did I mention that Jon Katz has an AUTHOR
    box you can use to exclude his stories?

    Michael, you fucking NAZI, I don't know how you ever got on Slashdot in the first place. Go on, mod down this post now, before anyone sees it!

    Michael may seem a little overzealous at times, but in a world where most people never hear about half the gradual erosions of their freedoms, care more about the latest Wal-Mart sale than the elections, and don't know the WTO from the WWF, I can hardly blame him for trying hard.

    Bonus question: Does Michael have an Author box?

    I prefer Slashdot's old style: Lots of Linux, UNIX, and Mac stuff...Very few Microsoft stories...Insane, bizarre hacks -- often related ...

    You've been around long enough to remember an older, better slashdot, but you haven't learned to use the preferences system? Get an account and learn to use it to transform this site into what you like -- all without having to change it for everybody else or inflict diatribes like yours (or mine) on everyone..

  • If you really feel as strongly about Jon Katz' writing as to tell him to "go kill himself" -- even as an expression of speech rather than a literal directive -- one assumes that you really wouldn't lose sleep over the good stories you MIGHT be missing by checking his author box.

    If you really feel that better anime news is found elsewhere, then the same thing applies.

    As for Michael and Microsoft and other topics/authors you find vary in quality and relevance to you: no one is forcing you to read any of them. I myself have a special filtering system in place... I simply scan the headlines and those I don't find interesting I don't pay any attention to. For those I think might be interesting, I read the paragraph of and then decide.

    It sounds like you're almost complaining you might have to resort to this actual sorting of information on your own.

  • My favorite line:
    Another problem I encountered was that the aluminum strap I used to secure the tailpipe of the engine to the kart frame just melted away. I'll have to make a new one from steel.
    This guy is nicely insane. You get the Darwin prize for things like strapping a jet engine to a go-cart. I'm jealous.

    And, by the way, Boston roads aren't any better than New Zealand ones :) -m

  • Now that would be a go-cart worthy of a GLH designation. GOES LIKE HELL!

    More like Darwin award to me :)

  • ooohh a grammar flame. you really zinged him.

    besides, language evolves. "doh" is now considered a word (see a previous /. article). i get sick of ye olde brits trying to hold on to an outdated form of language. i imagine it is largely because we have taken their language and propigated it world wide.

    whatever, it is sort of like bitching about typos. couldn't you find anything better in his post to respond to?
  • Do not even attempt to try to do ANY of this stuff until you have read up and fully understand the consequences of failure! Once you understand that, start experimenting, and take as many precautions as you can to protect your body.

    I had an email conversation with this guy on Friday (7/27), and I can tell you that I still have a ton of questions. He did say that a pulse jet engine could probably be built using off the shelf parts (steel piping and exhaust piping) - but it wouldn't last as long as using stainless steel piping (read: expensive) - but that much of the rusting and corrosion could be slowed by using high temp engine header paint.

    Typical pulse jets use a form of spring steel (or blade steel) reed or flap valves - that tend to wear out after a while (because of the flexing). In his conversations, he told me that he had hit upon a way to make a new type of valve (in both design and materials used) that actually lasts many times longer than common designs - in effect, advancing the state of the art for pulse jet engines.

    These devices can be dangerous - he shows one engine that he built that "exploded", but ripped down the side of the exhaust pipe as planned (he welded it to fail that way). Even so, it caused a lot of surrounding damage - buckling a nearby garage door. Had he not designed the pipe to fail (say, instead he had used common steel pipe) - it most likely would've caused significantly more damage - possibly lethal damage.

    Valved pulse jet engines are harder to build, mainly because of the machining of the valve. The valveless designs are much easier to construct - I am willing to wager that such a design could be built using common pipe and parts found at an Auto Zone and Home Depot. Probably take a few hours to put together (weekend project?), then a little longer to tweak and "tune" the engine to running resonance (once more, I must mention that reading up on how these engines work is important - better to build an engine than a potential bomb).

    Realize that pulsejet engines tend to glow red, sometimes near-white hot (actually, if built from standard, non-stainless steel pipe, it will fail before it gets that hot - blowing apart in a shower of hot steel first) when in operation for an extended (>5 min) period of time. They are LOUD - louder than you can possibly imagine. Being around one of these running engines for too long can desensitise your nerve endings - then when they resensitise afterward, they become hyper-sensitive for an extended (> 3 days) period - where every sound/touch/etc - is PAINFUL. Just ask Mark Pauline from SRL (I helped him set up for a pulsejet demo here in Phoenix last year - that engine was valveless as well - and quite powerful).

    So, in short - learn about them as much as you can, see one in operation first to know what kind of power you are dealing with (I heartily recommend an SRL demo, if at all possible), then learn some more - finally, buy the best parts, take the right precautions, keep a fire extinguisher and another person nearby in case of emergency - work outside or in a WELL ventilated large area. Know what you are dealing with - and maybe, just maybe - you will only walk away with a few burns, if you are lucky.

    Worldcom [worldcom.com] - Generation Duh!
  • Rolls-Royce product page for the Model 250: /default.htm []

    Not very good, but there it is.

    - - - - -
  • Forget the Darwin Awards. This is my nominee for 'Slashdot Post of the Year.' We do have such a thing, don't we Rob?
    Alex Johns
  • I saw a similar system (not exactly the same one) on TV used to put out one of the oil well fires in Kuwait. The system I saw was basically a large jet engine placed behind the stream of a large water hose. This was a fire that other methods had failed to bring under control for several days. They put the machine about 60 or 70 yards from the fire, turned it on, and within 5-7 seconds, the fire was out.
    It got me thinking about why they don't use a system like this in conventional fires. I then realized that such a system would be increadibly destructive to a typical building, probably doing more damage than the fire would. (Imagine being sprayed with water travelling at several hundred mph).
  • Ever hear of vectored thrust? Take a look at the US Space shuttle as it is launched and at the various stages where it discards the boosters and the external fuel tank. Think the center of gravity doesn't shift about some?
  • Yep. Did you get a look at the thin tube steel he made the cart out of? That kind of stuff you can bend over your knee. I'd make a real cart to begin with, or even better get one of those old Honda Odyssey four-wheel RV things (not the new soccer-mom Odyssey - see here [angelfire.com]) with the full roll cage and work from there.

    And his newer verison with the high-mounted engine? Where's the reinforcement? If he's lucky the engine won't bend that tube forward and snap his legs off like a mouse trap. But only if he's lucky.

    Don't even get me started on the brakes. OK, he can use a lathe - but machinist != engineer...
  • by gad_zuki! ( 70830 ) on Sunday July 29, 2001 @07:09PM (#2184202)
    Now that would be a go-cart worthy of a GLH designation. GOES LIKE HELL!

    More like GBH - Grievous Bodily Harm
  • Why don't you read his home page [aardvark.co.nz] and find out? It's explained quite clearly there.

  • KFG - rarely do you see posts on slashdot that combine the humor, wit and obvious expertise that yours do here. I throughly enjoyed reading them. Well done!
  • I recall some kind of rocket or jet powered go-kart at Burning Man. I don't think it was the same guy. The first year I was there I heard, but could not see (because of the crowd), the cart going around The Man just before he was ignited. The next year I saw the guy cruising around the desert in it.

    Mike [goingware.com]

  • Can you ever imagine me living in the suburbs? I don't think so.

    Neither do I, you need to have urban areas in order to have suburban areas. And New Zealand is all sheep farms. All of it.
  • Damn, some of these guys ought to be submitted to the Junkyard Wars guys as possible "experts".
  • by cybrpnk ( 94636 ) on Sunday July 29, 2001 @06:52PM (#2184208)
    Since this is propane powered, he should mount a BBQ grill onboard and do "shrimp on the barbie" as he howls along.....At $3 per minute he needs a sponsor, maybe Food Network would sponsor him. He could start his own TV show, Jet Chef...
  • Survival Research Laboratories [srl.org] have had a pulse jet kart [srl.org] for a few years now, but it's nice to see they have developed a pulse jet hovercraft [srl.org]... hehehe ....

  • Right, before modding me down, this is continuing from the beer cooler story. We have, in order:
    1. Mac's Black.
    2. Monteith's Anything
    3. Speight's Original Ale
    4. Anything Not Made by Lion
    5. Still Not Lion. It's not beer, it's a punishment for stupidity.
  • by PaxTech ( 103481 ) on Sunday July 29, 2001 @06:50PM (#2184211) Homepage
    It's quite similar to the tale of the Rocket Car [geocities.com].
  • I know V-1s were shot down during the war, but I'm not sure if they did it with 50-cal.

    The weapon that worked against the V-1 was the first computer and radar-controlled gun system, the famous SCR-584 [skylighters.org], developed at MIT.

    "Up to the time we got those 584s working, the Germans had been firing in the order of 100 to 110 buzz bombs a day, mostly in groups. Roughly 95 percent of them got through to London. .... At the end of the two weeks when I left to come back to the USA we were knocking something like 95 percent of them out of the sky before they got to the coastline.

    Guns much larger than .50 were used for this job, and with proximity fuses.

  • How long until the DIY Buzzbomb kit comes out?
  • Yeah that's just what we need, someone building a jet powered beer cooler [slashdot.org] and then using the jet engine to power thier go kart once thier beer is cold/consumed.

    But on the other hand, atleast your beer will stay cold on a beer tour!
  • Bah! We're way ahead of that. You can just shoot those down with a 50 caliber [fcsa.org]. Of course, that site won't tell you, but you just know there are guys holed up in cabins with 50-cal machine guns, which can probably shoot down a buzz-bomb, and can certainly bring down those black helicopters. I know V-1s were shot down during the war, but I'm not sure if they did it with 50-cal.

  • In the latest Popular Mechanics, Leno (Jay Leno, of late night TV fame) wrote an article about a guy who takes old (by strict FAA standards) jet engines, rebuilds them, and builds custom motorcycles and trucks for them. Best of all, they run on diesel. I quote, "McIntyre claims 320 to 350 hp and a hefty 450 ft.-lb. of torque. His motorcycles are priced at $150,000. The truck's a lot less. Of course, as a member in good standing of the 'More Money Than Brains Club,' I had to have one." A little later he continues, "I've ridden a lot of fast bikes but nothing pulls like this. It's shaft driven, not thrust driven, with a homemade two-speed transmission. You don't need more than two speeds becaue you've got those 450 ft.-lb. of torque. The shaft redlines at 6600 rpm. Don't even try to compute the power-to-weight ratio. It's better than a Formula One car's." And the best part is, it has a whopping 8.5 gallon tank (big by motorcycle standards) But it gets 4 to 6 mpg. In case any of you actually have interest, they're made by Ted McIntyre at Marine Turbine Technologies LLC, in Franklin, LA.
  • Indeed, I put well over 100 lbs of thrust onto my bicycle pedals and it's all I can do to maintain 30 mph over level ground for any period of time, despite a direct mechanical connection to the drive wheel of 98% efficeincy and a MUCH lower rolling resistence.

    Not to mention the fact that I'd have to put over 100 lbs of weight in my panniers to match his all up weight.

    On the whole he dosn't seem to be in any more danger than embaressment and annoying the people at the golf course. And perhaps some sheep.

  • If I had moderator points and hadn't posted in this thread I would give you a "funny" point.

    Thank you, I needed the laugh.

    Oh, by the way, you mispelled "I."

  • As is it happens he is. . .wait for it. . .


    Who can't spell for shit and knows it.

    Sucks to be you.

  • Hey, I've got an idea, why don't you go on the web and find some pictures of karts. Guess what, they're all built like ladders. In fact "Ladder Frame" is an official engineering designation for such frames.

    A good example of a ladder frame, and how outright dangerous and against all good engineering practices the idea is, is the Shelby Cobra. Everybody knows what a piece of crap that is.

    How about the Corvette? Not even a ladder frame! Just ONE tube down the middle. My God, it's going to just break right in half sitting at the curb. There arn't any triangles, were going to DIE!

    Oh no, I just noticed my backyard deck is just a bunch of sticks with sticks across the top of them. There's no triangulation, everybody off in a hurry!

    And Stonehenge, my goodness the untriagulated horry of it all!

    Sorry Sparky, but sometimes a simple beam is the appropriate engineering solution.

    And get new glasses Sparky. The frame holding up the jet engine was triangulated, although in tension, which for some reason you don't like.

    Let me propose that you perform this little experiment. Get a friend on top of a ten story building. Have him tie brick to a piece of parachute cord and let him hang it a foot over your head. So far so good. There is the brick hanging on 9 and a half stories of cord. If he were strong to hold it you could grab the cord and climb up, parachute cord can support well in excess of the 100 lbs of thrust the jet engine can produce. By the way, that's an engineering principle figure out the load and use a material of appropriate strength. He could have used line from a Weed Whacker and had exceptable reserves of strength.

    Assuming, of course, he didn't try to use it under compression.

    To illustrate, let him now turn the whole thing around. He'll be up at the top * holding the brick* and the end of the cord will be dangling over your head. Grab the end of the cord. Now have your friend *release the brick* and hold it up with the compression on the cord. Wear a good helmet.

    You see, under tension the cord could hold up the brick, and you, and Yo'Mama! Under compression it couldn't even hold up the brick.

    Now you know why sailboat masts and and airplane wings and pup tent poles are braced under tension.

    Go compress yourself.

    "Hey, what happened to Harry?"

    "Well, he went skydiving, and fancying himself an engineer he decided it would be better if the shrounds were under compression rather than tension, and . . . well. . . "

    Ah yes, the IEEE.

    "Harry what went wrong with your bistable multivibrator?"

    "I don't know, maybe I should have put the capacitors under compression instead of tension, or maybe the resistor has too great a torsional load on it. Guess I'll weld an I-beam to it."

    Yeah, the IEEE know their karts.

    And finally, let me see if I've got this straight, it is your contention that if I WERE really an engineer I wouldn't say so and put my name to it but would just use inuendo to denigrate anyone who did so under the cover of being an Anonymous Coward?

    Make for an interesting business card.

    "I can't tell you what I do because I'm a professional but that guy down the hall that SAYS he's an engineer is really a putz"

    There's a technical phrase we people who pretend to be engineers because we're willing to say so and sign our names to it use to dismiss any niggling little problem that won't seem to go away.

    "Bugger off!"

  • Indeed, the kart is not safe, as the builder himself admits.

    The point is that it isn't safe for the reasons that the builder points out, not the reasons that that were pointed out in the post that I responded to.

    The little wheels happen to be nearly ideal for a gravel road. Indeed the little wheels are nearly identical to, and came from the same source, as the very first racing kart. That kart
    was built by a man who made Indianapolis roadsters for a living. He knew what he was doing, and why. Some of his welds are messy, but don't have any obvious signs of porosity or other weld flaws that would dramatically effect strength. Indeed, I've seen bicycles with messier welds. They seem to be quite fashionable these days. By the way, I've spent the past several years living with a professional welder and have learned to tell the difference between a really weak weld and one that is just ugly. ( She makes locomotives by the way, real ones. From scratch.)

    As a bicycle racer I've gotten a fair amount of road rash from spills much higher off the ground than this gentlman sits, and at much higher speeds than his vehicle is capable of, ( I can go up hills, his kart can't), with nothing to protect me than a wee bit of lycra spandex. It has yet to prove fatal.

    His brake may appear dodgy to you but has proven to be a method quite acceptable over decades for karts chain driven by 5 h.p. engines. Indeed, if applied it would be sufficient to keep his kart from moving at all at the full thrust of his most powerful engine. In fact you could keep his kart from moving by the simple expedient of standing in front of it and HOLDING it still.

    Did you read the article? Do you understand that the device has a FRACTION the performance capacity of a bicycle?

    The photos have many points of reference to determine the cross section of the tubing. Chief among these is the diameter of the handcart tubing. That is 99.9999999 per cent certain to be 1". The axle bolts are also a reference for size. These are of a standard size for handcarts. If you want a reference for 1/2" look at his steering shaft. That is 1/2", which happens to be standard for a kart. Standard for a 2 ton car at 100 mph is only 1/4" larger than that.

    By the way, wooden 2x3s would be quite safe for his vehicle. I've built quite safe and ridable pedal powered tricycles of higer performance than this gentlman's device from * 1x3s.* You would obviously be rather surprised at how strong and safe a cart frame can be if constructed from * discared broom handles harvested on trash day.* In know. I've DONE it to prove the point to sceptics. Quite ridable bicycles have been comercially produced from 1" diameter * bamboo.*

    The tubing used by Telecom for it's maintance tents, last I inspected one, ( yes, I have inspected them, I'm a geek with a special curiosity for how tubing is joined for various puposes, you should see me ogling awnings), was 3/4" electrical conduit. Electrical conduit is MUCH weaker than mild steel. Electrical conduit is not made square. In any case I can tell it isn't of that poor quality be observing the cut off end of one of the tubes. Yes, I CAN tell just by looking at it in the picture.

    Yes, the gentlman perhaps has a bit more bravery than is good for him. I'd advise him to install a standard racing kart seat before taking any more rides. At that point about the only way he could get as much as road rash, given the perfomance capability of his vehicle, would be to be hit by a meteor while he was driving it.

    Oh yes, if I ever get pompous about spelling, which is something I never do, I promise to use a spell checker.

    When I get pompous about engineering questions about which I have specific training and experience in I'll rely on engineering. The strength of steel isn't affected by my spelling.

    Surely you know that attacking a poster's spelling when arguing a technical point is generally taken as both bad form and evidence that you have lost the argument? It's the equivelent of " Yo' Mama!" For reference I spell better in Spanish than English. A much more sensible language when it comes to spelling.

    You DO remember that this is the * World Wide* Web, don't you?

    Oh, " Sure I hope it dosn't happen" is either poor punctuation or poor grammer.

    Look it up in your Strunk and White.


  • Beleive it or not for the best quick and dirty explaination of general engineering principles relating to beams I recommend " Your Engineered House" by Rex Roberts.

    For any concept relating to the strength of items assembled from beams, and in engineering terms tubing is a beam, you can't do much better than " Racing and Sports Car Chassis Design" by Costin and Phipps. It's quite readable, and fascinating to anyone with an interest in classic tube frame racing cars. If nothing else by the time you're through with it you'll understand that you really CAN build an actual car frame with *broom handles* and hollow core door skins if you understand the principles.

    For wood as it relates to engineering concepts, both how to use it and how to work with it, any good book on building boats from plywood will set you up to build ANYTHING from wood, including cars and airplanes. Books on building airplanes from plywood are good but less accesable to casual reading, but don't really do a better job of explaining things than the boat people do, who assume the reader is an " Average Joe." Boatbuilding includes a broad range of skills and topics from basic woodworking to fine cabinetry, from basic welding to precision machining, from working with stuff from the lumberyard, to the most cutting edge composites. Learn to design and build boats and you can design and build nearly anything.

    It's also a popular subject so your local library ought to have literally dozens of good titles. Look for "Instant Boats" by Dynamite Payson for a good start.

    Ok, it's a litte embaressing to say it, but the Time-Life series of books is unbeatable for getting the feel for nearly any subject.

    Steve Smith Publishing makes available a whole range of books relating to performance and racing cars. These include practical guides to welding and fabrication for the "home" scratch builder of racing cars.

    Oh, and I'd reccomend Eric Sloan's " A reverance for Wood," because I have, well, a reverence for wood. It is the most overlooked and mistakenly ignored engineering material.

    Most important though is putting down the books and getting your hands dirty. 3/4" wooden dowels and 1 1/2" angle iron are free for the taking, ( broom handles and bed frames on trash day), do anything you can use these materials for and you are free to play without worrying much about cost. If you're willing to put in a bit of effort fairly large quantities of sheet metal can be salvaged from discarded refridgerators and other home appliances.

    And of course bicycles. Discarded bicycles are a wealth of material.

    PVC pipe is abundant and cheap, as is electrical conduit.

    Become a mad scientist for a while and just " dick with shit."

    Kinda like learning Linux.

  • Not all about, just a considerable amount. I study it. Just as some people study operating systems. It fascinates me. I have a love of brackets as well. It takes all kinds to make a world you know.

    I know little to nothing about any kind of steak. Never touch the stuff. It's "ucky."

    Determining the speed and direction of a vehicle from skid marks is fairly elementary physics that anyone can learn fairly quickly. I picked it up in Physics 101 at college. The real tire geeks, ( yes, there is such a thing), can extract amazing amounts of information from a skidmark. I don't know how they do it. I think it's magic.

    Sorry, I'm not a troll. She prefers simple flats and slippers although she does have a taste for olive drab clothing which she prefers to get at, oh the shame, Deb. Go figure.

    Someone has to make the trains you know. They don't just grow like mushrooms in the night.

  • by kfg ( 145172 ) on Sunday July 29, 2001 @10:24PM (#2184224)
    And apparently you arn't an engineer either, using 'thin' as a synonym for 'small cross section,' a technical misuse of the language that an engineer would never make. When an engineer uses the word thin in reference to tubing he is refering to its wall thickness.

    Assuming of course that he is using tubing. For all you know they could be solid bars. Of course as someone who has worked as an automotive engineer and custom builder of bicycle frames, racing suspension components and. . . yes, karts, I know that would be silly.

    Givin the nature of his project and his obvious penchant for using common and inexpensive materials where such are appropriate it appears he has used common 1" mild steel square tubing such as can be obtained at any home improvement store.

    If you were versed in such matters you would know that square tubing is more rigid in bending than round tubing at that 1" square has about the same bending stiffness as the 1 1/4" round tubing used in the best full bore 100 mph plus racing karts. Indeed, 1" tubing is allowed by the rules and considered quite acceptable for such racing karts, even when using the round stuff.

    As it happens I have a stack of 4' lengths of it right here, as it is my prefered material for quick and dirty prototyping. I defy you to bend even a 4' length of it across your knee. In fact you probably couldn't bend it by resting each end on a bit of 4x4 and jumping on it. Oh, it'll flex, but it won't bend. Cut it in half and it won't even flex. He used two tubes, the mechanical equivalent of cutting to half the length. I've built a street luge out of single SIX foot length of such tubing. It hasn't " bent across my knee" or anything.

    To give an example that most people might be able to relate to a bit more the top tube of a cheap Huffy bicycle, such as you can by at K-Mart for under $100 American, is made of 1" diameter mild steel ROUND tubing, ( remember, round is easier to 'bend across your knee'), exactly like the kind you can buy at the home improvement store. I don't think are many out there can imagine bending it across their knee. Indeed I use just such a top tube sawn from a discarded frame as a "cheater bar" when I need to exert hundreds of pounds of leverage an a short handled wrench. I've never noticed it flex AT ALL when used as such.

    You might be surprised to learn that the frame of the Lotus 8 racing sports car was made from only 21 pounds of 1" diameter * 18 and twenty gauge*, ( thiner than what you get at the home improvement store, much), round mild steel tubing. The car is still in service over 40 years after its construction, the first several of which it spent in serious competitiion.

    By the way, your street car is constructed of 18 gauge mild steel sheet, which you CAN easily fold across your knee.

    The brake he constructed is admitedly crude, but basically the same as that used on the early racing karts, and essentially the same as that still used on "fun Karts" such as you can buy at Sears today. Quite acceptable for his purpose and in no way indicative of a future as a Darwin Award winner. Easily as effective as a bicyle brake, quite possibly more so, and certainly as effective as that used to stop street luges weighing nearly the same going 80 miles per hour. Those brakes are called " Keds."

    As for the likelyhood of the frame supporting the jet engine bending I would like you to perform a little experiment. Take a child's tricycle, ( which is likely made from 1" diameter * electrical conduit*, no, I am NOT making that up, it is actually electrical conduit, and I defy you to bend the tricycle across your knee), and apply 30 lbs of force to it.

    Does it bend? Does the seat post, made of even smaller diameter tubing of even more dubious lineage, bend?


    Ok, apply 100 lbs of force to it.

    Gee, still not bent even though we have applied the maximum amount of thrust his most powerful engine produces.

    How about *1000* lbs of force? 10,000 lbs? A million? An *irresistable force?*

    Why won't the damn thing bend no matter HOW hard you push on it? Because it isn't an immovable object. It has * wheels.*

    The harder you push, the FASTER it goes as the energy of the push is converted into the kinetic energy of the tricycle. The actual force felt by tube pushed upon is actually quite small. This is the same fact of physics that lets a man pull a 10,000 lb box car with his teeth, or for you to apply a 100 lb force to the 18 gauge sheet steel making up the trunk of your car without it "folding across your knee."

    The frame itself is constructed from a handcart, itself constructed from 1" ROUND, (easier to bend across your knee than square), mild steel tubing. Hey, go bend a handcart across your knee.

    Now we know, because * we actually read the article* that the thrust produced by the engine was either 30 or 100 lbs. This happens to be in the range of force producable by a 5'2" 100 lb woman of indifferent athletic ablility. This means that if he were worried that he might run into an immovable object while the engine was running and the the frame might then fold over on him he could take the simple empirical step of placing the front wheels against his garage wall and * pushing on it.* You can simulate this experiment yourself by taking a handcart putting the load bed under something immoveable and pushing on it. Gee, you're looking a little blue around the gills now and the handcart hasn't bent at all. In fact the sheet steel of the load bed will bend before the tubing of the handle will and I defy you to bend even THAT across your knee.

    Look, I'm not averse to smartass comments, as this post itself is ample evidence, and I'm sorry if this post is a bit derisive, but you set the tone by deriding a man, who is clearly an excentric, as most of us geeks here are, ( by the way, computer or software " engineer" =! engineer), but just as clearly has a pretty good idea of what he's doing and the accepted practices of empirical engineering for accomplishing it. Your smartass comment only served to show that it is you that is =! engineer.

    No one likes a Cliff Clavin.


  • Yah, except jackass wouldn't need to do anything this sophisticated, from the couple of times I've seen this "show".

    More like he'd get a shopping cart, mount a gas can on the back, get in, light a match and scream "wheee" all the way to the emergency room.


    Hi! How are you?
    I send you this .sig in order to have your advice

  • God I like slashdot again. I read a comment on the last rocket story to the same affect but I don't think enough praise can be stacked on stories like this. I can only take so much politics and bad news before I can't even read /. anymore. It is nice to engage in a heated intellectual argument on occasion but my Nerddom derives not from bludgeoning people with my mind so much as being an enthusiastic techie. /. Can involve itself in as many Linux -vs- Microsoft flamewars as they want to because having no social skills is a hallmark of being a geek. But geeks don't derive nearly as much pleasure from mocking each other as they derive from the enjoying the sheer coolness of understanding one man's quest to achieve a Darwin award through technology!
  • If I remember correctly, my Estes Enterprise model rocket mounted the solid fuel engine about an inch below where the impulse engine ports were. That took care of the center of gravity issue. That was a number of years back when they sold the model.
  • On the origional Enterprise, perhaps, since its impulse engines were mounted at saucer level, well above what you would take to be the ship's center of gravity (although I suppose you could surmise that the warp engines were heavy enough to offset this). The warp engines themselves didn't provide propulsion directly in the context of Newtonian motion, so this is a non-issue.

    The Enterprise D, however, seems to have had her main impulse engine mounted in about the center of the neck, which would seem to be much closer to the COG than the Ent/Ent-A.
  • not to mention on the roll bar above his head...

    Hate to see what would happen if he actually rolled it.. (already admits to doing 30+ mph with tough one handed steering and almost no brakes)

    Not to mention he had no one around to film... which means no one to get help when he is 50 yards into the woods pinned against a tree....

  • What some people do to get their jollies..
    Whatever floats your boat...

    So... I grabbed one of my midi-sized pulse-jets (about 30 lbs thrust) and bolted it to the side of the kart.

    As I mentioned -- the kart doesn't even have a seat yet so I clamped a piece of wood onto two cross-members to stop my backside from scraping along the cement.

    This board was also a handly place to lash the 20lb propane tank which provides the fuel for this jet.
  • by vectus ( 193351 )
    should we call the people who do the darwin awards, or do you think they'll find out about this on their own?
  • by IdahoEv ( 195056 ) on Sunday July 29, 2001 @10:10PM (#2184232) Homepage
    I work in the aviation industry, and I can think of a better type of Jet engine to use.

    I don't work in the aviation industry, but at least I read his site. He knows full well that pulse jets in many ways can't compete with turbine jets. He's researching pulse jets because everyone else dropped them in the 1950's and he thinks there's still interesting work to be done with them.

    If you read his full site, you'll note that he's also built turbine jets and attached them to the go-kart as well. He even re-engineered the casing of the turbocharger his turbine jet was made from so that it could drive a gearshaft and drive the kart directly instead of via thrust. Just as you describe, except that he built the thrust shaft himself.

    But he's really working on pulse jets, and has already made big advances on them. Pulse jets normally require very long tubes; he's cut the minimum length in half. He's designed a new type of valve that lasts much longer than previous pulsejet valves... etc. The list goes on. His work has even won him some large research grants and corporate sponsorship, fairly impressive for a backyard engineer.

    Yes, I'm sure you could build a more powerful go-kart than his, but that's not what his work's about.

  • Hey thanks.

    I meant to put the link to their page in my comment, but my dial-up connection was slower then molasses last night, so I just threw it together from what I remembered of the 250 model. Newer models actually generate almost 700 shp! Of course, if you didn't want to pay the big bucks you would have to find an older model. And with a used engine, using some backyard engineered gearing system, it would probably cut the amount of horsepower to the wheels, but it sure would be fast!
  • Well obviously. I was just throwing in an idea. Honestly, you might actually be able to get a few engines in bulk that were out of service for relatively cheap. From that you could probably put together a functional model. And granted, being older it would be less effecient but even if there was a 50% power loss going to the wheels that still would be a 200 hp go-cart!
  • Geez. Excuse me. I was just posting a comment on what my jet powered go cart would be. Honestly, the reason I didn't post more info was that my dial-up connection decided to drop down to speeds below 1k/sec last night. And considering the hits on this guys homepage at the time of the posting, I didn't have much chance of getting through. Building it from the ground up, well then yes a pulse jet makes sense. It's simple, has few moving parts, and doesn't require too many advanced parts. My idea was from the perspective of putting one together with as little work as necessary. cheers
  • Hey, I didn't mean to insult this guys work. It's pretty damn cool that he got a pulse jet to drive a go-cart. My perspective was if you want to build a Jet powered go-cart using off the shelf components would be fastest and the most effecient.
  • by Mac Nazgul ( 196332 ) on Sunday July 29, 2001 @06:54PM (#2184237)
    I work in the aviation industry, and I can think of a better type of Jet engine to use.

    Just from memory, the Allison 250 comes to mind. It is small enough to fit behind the seat of a go-cart, prolific enough to find used parts and engines cheap enough. It's also used in helicopters, so all you would have to do is hook up some time of gearing system to the rear axle, since it already has a power output shaft. Not to mention one or two people could easily lift it and move it about. I think it weighs around a hundred pounds or so. And it generates over 400 shaft horsepower!

    Now that would be a go-cart worthy of a GLH designation. GOES LIKE HELL!

  • Actually, the Japanese had serious studies about building a pulsejet-powered plane for kamikaze missions late in World War II.

    It's a very good thing that machine was never produced. Imagine a kamikaze plane flying at over 420 mph at only 200 feet off the ground--it would have been just about impossible to intercept given the speeds of carrier-based fighters and the quality of AA systems on US Navy ships in 1945. We're talking much lower altitudes than the V-1 buzz bombs used for their cruise altitudes; this would have resulted in the kamikaze plane being lost in the low-altitude clutter that plagued early radars.
  • you just couldn't resist, could you?

    /me goes back to chasing sheep like the hard Southern man that he is... ;)
  • by angry old man ( 211217 ) on Sunday July 29, 2001 @07:02PM (#2184240)
    Did anybody else notice that the jet was mounted *slightly* above the go-kart's vertical center of gravity?? If that thing was ever able to produce some real power, that guy and his go-kart would be sent off in somersaults.

    I always thought that the Star Trek Enterprise would have a similar problem.

  • if I remember correctly. So it's not a totally obscure form of propulsion.
  • by Anaxagor ( 211917 ) on Sunday July 29, 2001 @07:08PM (#2184242)
    Since when do sheep run that fast that New Zealand men need jet powered go-karts?
  • mechanics of materials by Gere and Timoshenko is used in my university for a first course in mechanics of materials. The book has it's flaws but for a basic introducting to mech. of materials it's alright, it doesn't really require prior knowledge of mechanics besides some basic physics and some math.

  • Except, you have to be able to do something with a fixed 6K RPM....

    No, your right - go like hell indeed....

  • My favorite has to be the MR-2 with 3 jets on it Wasn't that advertised on Ebay a few months ago? Can't remember how much it was going for (was cheap though).
    Has anyone seen this sig? If so, call +44 800 seensig
    Discuss wireless networking ...
  • I agree.

    It's easy attacking someone as "Annonymous Coward", no matter how cowerdly that may be.

    It's also interesting when these "elements" make Slashdot their HOME, and try to "ruin a good thing."

  • by Schezar ( 249629 ) on Sunday July 29, 2001 @06:45PM (#2184247) Homepage Journal
    Hmm... This has all the makings of another Darwin Award winner ;^)

    Cat-girls are the driving force behind my VR research.
  • Thats pretty funny, in the body of your comment you loyally defend the jet kart man against someone who apparrently didnt read the guy's site. Then in your tag you proclaim death to SUV owners because they waste gas and are dangerous.
  • The army has a system like this to decontaminate large vehicles like tanks and apc's, we just run the decontaminating solution into the exhaust of a helocopter engine! cuastic chemicals at serveal hundred degrees and traveling at several hundred MPH gets everything in every nook and cranny done in a couple of minutes. This would clean your family car PDQ, the bare metal would realy shine!
  • that way the saucer had propulsion if they had to seperate the disk from the rest of the ship, there was also a seperate command deck in the lower half. presumabley the crew could evac to either half in emergencies. I've seenthis in the tech drawings published way before Next Gen demonstated it.
  • browsing his entire site i found an interesting page about how a pulsejet works [aardvark.co.nz]. it's a brief explanation, considering a pulsejet is a pipe full of hot flaming stuff.

  • His Links Page [aardvark.co.nz] was an excellent resource. After the beer cooler story, I found this and then spent most of Sunday reading about how various folks built their engines.

    I highly recommend checking out some of the homebrew jet websites these guys have. Its wild to see the different approaches they take to reach the goal of self-sufficiency. One guy used plain old cast iron pipe [tripod.com] you could buy at Home Depot and got it working. Another is working on an engine that uses a turbocharger from an M-60 tank! [earthlink.net] He's also got one that has an afterburner on it with some REALLY cool pictures.

    This is quite the hobby. On guy built a really sweet engine [home.net] that used a PLC to help start the engine which is a multi step process. His worked so well he sometimes had trouble keeping his cart braked. Interesting to see how folks also try various fuels from K-1 to LP gas to Diesel.

    I honestly was blown away by the time and effort folks put into one of these just to have it run - but it really was a blast browsing all these sites all day - careful!! You might get hooked! :) Geeks with jet engines is a scary prospect!

  • Pulse jets are an inefficient design that has been entirely superceded by other engines - but wow.

    IANA Rocket (or Jet) Scientist, but off the bat I'd say that these Pulse Jets of his beat the pants off other jet engines in two categories: cost of manufacture and simplicity. So long as other parameters like thrust, weight, economy and whatnot are in a useable range, these pusle jets are viable alternative to more complex jet engines...within the proper niche.

    And heck, this guy managed to make significant improvements to the original design all by himself. Who knows what advances might come if a commercial entity invests in the research?

    Um...assuming, of course, that the guy hasn't Darwinized himself by then. ^_^;

    Hail Eris! All hail Discordia!
  • See if they get laid first... if they breed before they explode it really isn't Darwin fodder.

  • It isn't *all* sheep farms. Some of NZ is indoors.
  • by JoeGrind ( 324053 ) on Sunday July 29, 2001 @06:50PM (#2184256)
    Anyone seen that show "Jackass" on MTV? Sounds like an accident waiting to happen.

    "You'll shoot you're eye out!"
  • I don't think the reinforcement of his engine mount is going to matter heads or tails if he gets in an accident and there is nothing holding him into the kart. He is STILL running tests while sitting on a plank of wood. This is not indicative of proper highway safety. In a rollover situation (the most likely accident, it seems, considering his steering and high engine mount) his body will be thrown clear to roll down the highway at 30-60 mph without a helmet, gloves, or braces on all of those joints that could snap in the wrong direction. It appears to have all of the safety of a motorcycle, and you know what THAT means.

    That means we should start a fund on Slashdot to buy the boy a seatbelt and a helmet.

    Not that I'm deriding the project... It actually seems like a really fun, geeky hobby that will create something the neighbors will talk about for years. "My son's Bay-o wolf clu-star? I don't know anything about that, but this guy next door has a freight loader with a jet engine!"
  • Maybe GM will start perfecting this and put it in a car.
    These guys from NZ are do-it-yourself masters...
  • Fire fighting is another use of the jet engine, try this GAG [bullion.org.za]
  • Uh-oh... it looks as if the frequent running of my pulsejet and gas turbine engines has finally taken its toll on my nearest neighbor. This realtor's sign went up last week and it appears that they're now looking for a nice QUIET place in the city.

    This guy is all old and cool, he's gotta be SOMEONES grampa why not mine?
  • I don't get why all of you think this sounds so dangerous. 30 lbs of thrust is not that much, and he can easily shut it off by turning off the propane valve. Also, since he has experimented quite a bit with this jet (he actually makes and sells them), he knows what to expect.

    And of course there will be no Darwin award unless he dies (those are the rules), which seems MOST unlikely.

  • by mamba-mamba ( 445365 ) on Sunday July 29, 2001 @07:33PM (#2184262)
    The guy sells them in kit form. But since there is only one moving part I imagine the kits are pretty easy to assemble. They range in price from $120 to $390, depending on thrust. He also sells them assembled for slightly higher prices.

    Scroll to the bottom of this [aardvark.co.nz] page for more info.


  • This is pretty cool, and I would like to use it on my own go kart, but any idea how much it would cost?
  • A friend sent this link to me a while back. We started thinking about other applications this could be used on such as a snowmobile or a go-kart.

    Low-Budget Turbine Jet-Boat Project [gas-turbines.com]
    MPEG [gas-turbines.com]

  • I think he ought to consider spending a little more time designing real brakes and a more functional throttle before he bothers strapping more thrust onto that kart.

    If not, he might make it into the Darwin Awards [darwinawards.com].

  • by SixTwelve ( 451492 ) on Sunday July 29, 2001 @08:43PM (#2184266) Homepage Journal
    It's been far too long since a new gadget was added to shoes. In the halcyon days of footwear (that was the early and mid '80s for you youngins) we had a radically new pedal contraption every couple of weeks! Shoes with no laces [nike.com]?! That's a loafer! Shox? We've had spring loaded tennies for like a decade.

    No. What we need is power.
    I want to be the first kid on my block with pulse jet game!

  • I tried to accelerate my bicycle using a twin pulse jet once, right after I had read up on how a pulse jet works in a book on WWII airplanes.

    Let's just say it didn't work and I had a different bicycle afterwards.


    I prefer ramjets over pulsejets because they're generally more durable, especially when homemade (but you do have to take care of your materials). For ram jets, in retrospective, the bike would've been too slow anyway, however.

  • If the jet is mounted on the top of the rollcage, doesn't that move the center of mass dangerously high? Also, what happens if the roll cage is actually used as a roll cage (that is, the kart flips over)? The destruction of the jet is bad enough, but what about the ruptured gas line?

    It would seem to me (and I am not an engineer of any sort, so take this with a grain of salt) that a better idea would be so somehow mount the jet below and behind the driver. Say, you have the basic chassis of a wooden or metal platform on wheels, mount the engine on top of that, and then have another platform mounted above that where the driver sits, being careful not to obstruct airflow for the jet. Alternatively, couldn't this guy do a modified version of the original design, with the engine behind him and to the side, but with some sort of partition between the driver and the pipe? Either option should eliminate the risk of getting burned by the pipe, and would move the center of mass lower, as well as reducing the likelihood of the cart rolling onto the engine (assuming it still has the rollcage.

    I was also wondering, is a turboshaft engine really the best way to go to improve acceleration? This guy mentioned that acceleration improved markedly at 10 MPH, so why bother with the added mass and hassle, and failure risk of a turboshaft? Why not just add a small conventional go-kart engine to get the kart up to ten mph or whatever? Then just turn on the jet and shut down the IC engine. The ICE could also be used in a racing situation if the jet failed, or the slope was too great for it.

    USA Intellectual Property Laws: 5 monkeys, 1 hour.
  • He's been programming since god was a lad, builds custom PCs in his spare time, and is still a badass at god-only-knows how old.

    USA Intellectual Property Laws: 5 monkeys, 1 hour.
  • He already explained that the acceleration produced by the pulse-jet on this kart is so slight, you could stop the darn thing by standing in front of it. The brakes are more than adequate, and in fact are routinely used on the "go-karts" you buy at Sears. All this is explained in his series of posts - so read them.

    That said, the throttle does need work, but you have to admit there is something to be said for the adrenaline rush of trying to control a homemade jet engine that backfires like crazy while steering a go-kart one-handed at 30mph.

    USA Intellectual Property Laws: 5 monkeys, 1 hour.
  • Since the propane gas tank on the cart would be experiencing cooling effects, the guy really could put that tank in a large bucket of water and put beers in it. Of course, the water might slosh a bit...and the extra mass might be excessive.

    USA Intellectual Property Laws: 5 monkeys, 1 hour.
  • Its interesting to note that this thing is only capable of 50-60mph. While there's undoubtedly room for improvement, current normally powered combustion engines can assuredly match this speed. An interesting aspect of this would be to add wings, increase thrust, and improve aerodynamics... The first flying go-kart!
  • He's got some pics of cars with turbojet engines in the back. He lists some really low thrust for the first one (Honda) and I was wondering what your thoughts were. He mentions how part of the turbine was removed, but what part? If the row(s) of blades turning a generator were removed, I could understand that. I just don't see why someone would remove the turbine blades, but not the corresponding stators.

    Also, even with the remaining stators diverting flow inefficiently, I wouldn't think it would reduce the overall thrust so much.

    That's Mr. Eradicator to you.
  • Apparently you haven't heard of the latest New Zealand invention: indoor sheep farms!

    (And rumour has it that some bloke, building upon this success, is developing an indoor sheep farm, powered by pulse jets, that also cools beer!)


  • Did you read about his latest project, "The Ultimate Water Bomb"? He closes the page with "I'm just crazy -- not stupid ;-)"

"The number of Unix installations has grown to 10, with more expected." -- The Unix Programmer's Manual, 2nd Edition, June, 1972