I am about the least Santa Claus looking guy around. (Well, okay, my hair is getting to be about the right color.) I did chuckle when I saw that frame myself, though. I had on a blue shirt, and a red fleece sweater that I got in the boys' department at Old Navy because the mens' department didn't have anything in stock that fit me. It fits okay in the chest, but the arms are a tad short, and sometimes they ride up. _________________ H4 + various skills (only foot-launch so far)
WW UltraSport 147, WW Falcon2 170, PacAir Vision Mark IV 17
My HG wiki profile and my flying blog
Here's my first VERY ROUGH CUT at a set of build instructions for the cart. It's really not much more that a bunch of pictures and some of the notes I thought were important. I'll be improving the doc soon.
BTW, just so Rob knows he's in a lot of very good company (and I do use that term loosely), we're getting called "bozo's" all over the internet by guys like this PhD.
BTW, just so Rob knows he's in a lot of very good company...
I admit there are plenty of people that think this cart can't work. But I think Rob might be alone in his ability to come up with a video of a barrel rolling toward him when he pushes it away.
Wow, the scienceblogs crowd sure includes a lot of people who are willing to toss out demeaning names ("bozos") without thinking things through enough to realize that they're flatly wrong. And apparently at least one PhD who nees to send back his degree. I was going to open my mouth over there, but it's just not worth it... _________________ H4 + various skills (only foot-launch so far)
WW UltraSport 147, WW Falcon2 170, PacAir Vision Mark IV 17
My HG wiki profile and my flying blog
It's kind of fun taking a tour around the web (scienceblogs, boingboing, randi) to see the ranting directed against you people and your witchcraft-powered cart. Also nice to see that some people are able to step back from their stubbornness, understand the real answer, and apologize for calling you bozos (though disappointing to see that others are able to get dragged past their stubbornness, understand the real answer,and claim that they now understand it but you don't. )
Anyway...
A few comments if you decide to go ahead and build a big, rideable version:
- I've seen comments elsewhere that you're thinking of using a "one-shot" spool transmission. While this does nicely solve the 90-degree twist problem, in my experience this approach usually turns out to be a headache that causes more problems than it solves. I know of a couple of human-powered devices that tries this, and neither worked very well.
- Think about going with shaft drive, like you did in the little cart. Depending on which axle you decide to drive from, you might need two sets of bevel gears, but you might be able to find some ready-made gearboxes that will do the trick, just like you did with the tail-rotor gearbox. I'm thinking about whatever is used by shaft-drive motorcycles at the rear wheel, maybe, or the differential from some tiny car.
- Weight isn't really an issue for a component like that (although efficiency and low drag are). You probably don't need to worry much about weight at all. In fact, if Mythbusters were to build one, the best way to save weight would probably be to put Kari Byron in the driver's seat rather than Jamie or Adam. Which would probably be a good idea on several levels.
- One nice feature of this is that there's no need to worry about fairing the chassis, since the airspeed of the chassis will never be very high.
- You will probably want the biggest prop you can swing, and that will be limited only by how high off the ground you can manage to put the hub. Bauer's cart was as big as it was for a reason.
- Prop efficiency may be a very big deal. If it turns out that you need a really good prop, I know the ideal guy to design it. He's an MIT prof, perhaps the best propeller designer in the world, and he likes oddball projects like this. Designing the ideal prop might take him literally 15 minutes. I can put you (or Mythbusters) in touch with him if need be. I have no idea how busy he is these days, but I don't think this would take him much time. (He could also do a phenomenal bog of actually building a prop, but it's far less likely that he'd have time for that.)
This may well be stuff that you already have a solid handle on. I'm impressed by what you have done thus far, and will be pleased if you do more. Hope you don't mind the unsolicited kibitzing. Carry on. _________________ H4 + various skills (only foot-launch so far)
WW UltraSport 147, WW Falcon2 170, PacAir Vision Mark IV 17
My HG wiki profile and my flying blog
Over on the Randi forum, a critic continued to disbelieve us and was convinced that it was only running on kinetic energy (for 2 freakin' minutes off of a 1oz prop?).
Anyway, he build a single wheel version and a turntable (endless treadmill).
Of course as everyone knows (well, everyone but Rob and a very special GTech professor) it goes round and round until someone turns the power off.
Lots of great points there. I particularly like the idea of the motorcycle shaft drive.
We have a guy that can probably give us a good prop design, but I sure wouldn't mind getting the input from your MIT guy (that's like the GA Tech of the north - right?).
Before we contact him maybe you should check and make sure he doesn't think this is perpetual motion.
quote="spork"]Lots of great points there. I particularly like the idea of the motorcycle shaft drive.
We have a guy that can probably give us a good prop design, but I sure wouldn't mind getting the input from your MIT guy (that's like the GA Tech of the north - right?).
Before we contact him maybe you should check and make sure he doesn't think this is perpetual motion. [/quote]
though disappointing to see that others are able to get dragged past their stubbornness, understand the real answer,and claim that they now understand it but you don't. )
We found this analysis of his particularly entertaining. Fortunately, the digs against JB and I are well documented (and copyrighted). Here's a copy for anyone that might be interested, since he had the good sense to take it off his website. Of course it remains as the crown jewel at the "DDWFTTW FAIL Museum".
though disappointing to see that others are able to get dragged past their stubbornness, understand the real answer,and claim that they now understand it but you don't. )
We found this analysis of his particularly entertaining. Fortunately, the digs against JB and I are well documented (and copyrighted). Here's a copy for anyone that might be interested, since he had the good sense to take it off his website. Of course it remains as the crown jewel at the "DDWFTTW FAIL Museum".
...amazing...a fan blew his contraption up an incline. i wonder if he was able to measure down wind faster than the wind. (or up an incline powered by a fan...) i want documentation!!! all he has is photographic hand waving and unobtanium...
i really look forward to seeing mythbusters make this thing and see it go dwfttw! this is gunna be cool. _________________ "Never Land On Your Face"
H3
FL~FSL~CL~AWCL~AT
The Hangar--> Moyes Litesport 4~Vision Mark IV 17~UP Gemini
Mylar balloons will maintain buoyancy for a long time, much better than rubber ones. When they first came out, I think I trimmed one and had it hanging out in the middle of a room for a day or so.
We predict the need to control the altitude of the balloon simply because of the swirling winds and changing temperatures of the real world.
Make a balloon absolutely neutral and try to hang it head level while it blows a mile down course -- not a chance. It will hit the ground now and then (and blow the test) or rise too high and gain and advantage above the gradient.
Not sure the control method, but I predict we would need one.
JB
Probably already been said, but I think the streamer on the back, that other youtube guy had was pretty self explanitory. The only way that streamer can point backwards is if it's going faster than the wind, but I wouldn't place it directly behind the prop, that could be seen as suspect. _________________ C4 13, KTM 300 2-stroke.
Probably already been said, but I think the streamer on the back, that other youtube guy had was pretty self explanitory. The only way that streamer can point backwards is if it's going faster than the wind, but I wouldn't place it directly behind the prop, that could be seen as suspect.
If you look closely you can see that Jack's streamer was actually well off to the side. Unfortunately this is not evident from the angle at which the video was shot.
I'm more inclined to use smoke canisters so you can see a bit more "history".
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(or up an incline powered by a fan...) i want documentation!!! all he has is photographic hand waving and unobtanium...
this is gunna be cool. 