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jcline - n/a
27-Jan-07, 11:15 PM
Hi folks,



I am currently a graduate student in the process of designing my thesis project. After a conversation with my professor, I have decided to employ hover technology in my design. To give you a little background on my project; I was recently given the opportunity to design and build a functional, mobile artifice for our local museum. The hope is to explore the poetics of organization and the ritual of use. When complete, it will provide an efficient service platform from which to serve food and drinks during museum exhibitions and social functions. Once completed, the cart will be donated to the museum.



Basically I am going to create a bar from which to serve patrons drinks and food. The bar will only move from storage to the designated service area when needed. Think of it as a big rectangular box, approximately 3' wide x 3' high x 7' long. I haven't exactly decided on materials yet but I'm hoping to keep the cart to around 600 lbs.



So this is where I need your help. I have decided instead of using standard caster wheels to move the cart, I want to make the cart hover just above the ground (approximately 3/4"). When needed an employee can simply start her up and push her to the designate area. Once in place everything will be turned off and the cart will rest on the floor. After the event, the cart will be started up and pushed back into storage. The design and interface has to be completely user friendly because I will not always be there to instruct.



Since my experience in in this sort of thing is well non-existent, I am wondering if anyone in this community might be willing to offer some needed advice. One of my first concerns is selecting a type of motor or motors to use for this application. I will also need a batteries, fans, throttle, ??. Since weight is an obvious issue, I need to keep the 'powerplant' as light and efficient as possible. I have not decided if I will use a skirt on this thing. Oh, and I figure the fans will only need to run for a short period of time (maybe 20-30 minutes) for each charge.



By the way, I read through "Electric powered Hovercraft..." thread posted a few months back. Some of it was very helpful but my application is so specific I found it hard to apply the tips to my project.



Last thing, this all has to be done by middle of April. =)



Thank you for your time!



John

tonybroad - n/a
28-Jan-07, 11:25 AM
your design is possible from an engineering perspective but i suggest you consider the following:



to lift 600lbs over a 3'x7' area needs a fan to produce a pressure of 1370 Pa by my calculations (Pressure = Force/Area) which is a lot more pressure than we produce in our hovercraft skirts(because we have more area and less weight), stability may also be an issue but any more than 3' width and it wont fit through a door



consider what happens if there's a step in the building or a slope ?



air escaping from the skirt will blow dust and anything else in it's path all over the place



an electric powered fan will be very noisy at the duty you'd need to run it



in my opinion (as a university lecturer of engineering) it is not viable for the reasons above, however you might add value if you have considered Hover technology as an option but then rejected it with justification for it's rejection rather than just abandoning it as an idea



i think you have a bit more work to do before you can explore the poetics of organization and the ritual of use



you're not the last undergraduate to leave a thesis to the last minute - middle of April !! you're going to be busy i wish you good luck



Tony

darwin - n/a
28-Jan-07, 12:21 PM
Have a look at this site





http://www.taunton.com/finewoodworking/ToolGuide/ToolGuideAr (http://www.taunton.com/finewoodworking/ToolGuide/ToolGuideArticle.aspx?id=27031) ticle.aspx?id=27031



Geoff

Keith Oakley - n/a
28-Jan-07, 12:24 PM
I agree with Tony that the dust and noise issues might make the idea untenable. However assuming you only want to move it across a flat museum floor with no steps the higher pressure you need (3 times the app 10 lbs/sq ft we use) might not be an issue - you just need to find a compressor that can deliver the pressure and airflow you need. Assuming you use a very small bag skirt (say 1-2 inches high) at high pressure the stability might be acceptable given the low speed and maybe someone walking alongside to stabilise it. I'd aim for mains power on a lead given the application.

jar2 - n/a
28-Jan-07, 01:51 PM
John,



Have a look at this:

http://amasci.com/amateur/hovercft.html (amasci.com/amateur/hovercft.html)



One of my kids built one (not exactly a major project!) and it will hover a surprising amount of weight (around 700lbs) on asmooth surface.

jcline - n/a
28-Jan-07, 08:18 PM
Thank you all for your help and insight. As I continue to do research and gain valuble feedback from people such as yourself, I am constantly trying to adapt it the design of the cart.



The cart will not have to travel over any steps in the museum. There might be one instance where it will have to go down a handicap ramp but it is only about 6 feet long with an elevation change of about 10 inches. The noise is relative. It will only be noisy in the time it takes to move the cart from one place to another. I figure the museum to be relatively dust free. It is a museum after all! It will be only traveling at walking speed at best. The employee will be pushing the cart to the desired location. Once in place it will rest on the floor.



I have access to a large format laser cutting machine and am thinking of building the cart entirely out of 1/2" acrylic. I feel it could be an incredible experience to see right through the entire cart, working parts and all. This is still in debate but for now it's what I'm trying to work with. The basic thinking behind the total weight I mentioned above is: a 4'x8'x1/2" sheet of acrylic weighs approximately 90 lbs. If I can build the cart out of 5 sheets, that's 450 lbs of "structure/storage space" potential. The other 150 lbs is allocated for powerplant requirements. I am hoping to start a full scale mock-up by the end of this week. I will use it for testing and tweaking the design and function.



The hoverpad you mentioned Geoff is almost perfect! Thanks for that link. The only issue I might have with it is that it cannot go over carpet. There is a small portion of carpet the cart will have to move over to get to the auditorium in the museum. I'll definately follow up on it though. Thanks!





Thanks for the link to the small hovercraft, John. I think I might try and build one of those this week to get a better idea of how all of this stuff works.



Can I get away with not constructing a skirt? I thought maybe there could be an air chamber on the bottom a couple of inches thick. The dischared air would flow into this chamber and out an evenly distrubuted set of holes cut into the bottom platform surface. The holes could be 1/4" in diamter at 1/4" spacing over the entire 21 square feet. Could this work or am I compltely off my rocker?



Thanks again guys. I think I'm finally starting to get somewhere with this!

jcline - n/a
28-Jan-07, 09:05 PM
So I've done some research into cordless leaf blowers. They seem to offer an "all in one" opportunity for my powerplant needs. I have found dozens out there but sadly it seems they have very little continuous operation time (no more than about 10-15 minutes).



John

jcline - n/a
29-Jan-07, 07:43 PM
how about one (or two) of these modfied with a proper fan?



http://www.blackanddecker.com/productguide/product-details.a (http://www.blackanddecker.com/productguide/product-details.aspx?productid=16345&toolview=2#details) spx?productid=16345&toolview=2#details

jcline - n/a
7-Mar-07, 03:01 PM
It's up and running...



http://www.youtube.com/watch?v=6GGlgD3qs3I