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View Full Version : Discussion building a hovercraft for $100?


Surnia
Jan 24, 2009, 12:09 PM
Hello everyone, been lurking around this forum a lot, and along with my local Archery club we've decided to build a mobile target, possibly built upon a hovercraft design. However, our limitations are under $100, and we're stuck with some... less than ideal RC materials for durability and electronics armor concerns (with the arrows and all xD).

Having no experience with scratch built RC, we're looking at using some rather interesting designs I'm hoping some of you can help us on? We're not quite sure about the limitations on hovercraft designs, and would appreciate some input!

The current design we've come up with is a main lift fan, a forward thrust fan, and instead of rudders, we use a set of 4 computer fans for directional control.

Radio
- some cheap 6ch radio with 100m range found on ebay, not designed for RC vehicles (looks like a garage remote but with 6 buttons) but it suits our needs and price bracket.

Motors + Fans
- 24V motor attached to an impeller fan for lift
- 24V motor for forward thrust, i'm assuming a regular fan unit
- 12V computer motors for left/right turning, and lateral movement

Batteries
- two 8000mAh lead acid batteries for the lift/forward fans, 24V
- single lower mAh battery for the directional controls, we haven't settled on one yet since it was a later decision (we tried to wire two to each lead acid battery, but it led to issues with the circuit diagram)

Dimensions
- we're going to attempt to use a 80x60cm base due to size constraints at our range
- height will be 1.5m total (not hovering), including target block (foam target for weight concerns)

Materials + weight
- 5kg total estimated weight
- plywood base for the electronics to sit on, and the air channels for the skirt
- 2x4 wood armoring for the batteries and radio (our target butts are made from 2x4, so its an easy replacement for us)
- old pants for skirt, sealed with something rubbery (we haven't figured that one out yet, but one idea was rubber cement). repairs will hopefully be done and sealed properly with duct tape >_> We're going to seal it to the body by sandwiching it between the plywood base and another piece of wood, and clamping it down as tight as we can.

Now with these specs, we don't know how fast our motors will run (haven't been purchased yet), but can anyone give a ballpark idea how much air we'll need to be moving to lift a 5kg mass? also we're not quite sure about battery life running such a setup (we do have 16000mAh total though...).

Also we're not quite sure how to design the air channels for the skirt, how close does the air need to come to the skirt for proper inflation and hover? We're guessing they need to be channeled pretty close to the edge to accommodate for stability and proper skirt inflation, but we have no idea how close it actually needs to be.

Many thanks for reading, and any help is appreciated!

Xmodgeek
Jan 24, 2009, 08:26 PM
Hahaha my archery club had a similar idea wanted if for 3D practice, we pondered a hover craft so it could move in all directions and worked on different teran. But that was 4 years ago before I moved from Ohio... but any ways we didn't do much with the idea some kid did tape a foam target to his gas R/C car and we took pot shots at it but that was about it. Back then tho I knew vary little about R/C stuff.

That said and with my recent hovercraft endeavors, I think it doable but the base would probaly needs to be bigger with the high CG from the target. I can't really say any thing about your motors tho, not vary much info but I don't think PC fan will help you much expeshaly outside if a slight breeze comes along it could take the target with it. We were thinking of using a leaf blower as a lift fan. Have you bought any thing or have any thing for the project yet? I'm wondering how you plan to controller the motors.

Could you link the radio page from ebay and any mor info on the motors and props please

Surnia
Jan 24, 2009, 08:55 PM
6 channel remote (http://cgi.ebay.com/RF-Wireless-Remote-Radio-Control-Switch-6-Channels-NEW_W0QQitemZ280305209494QQcmdZViewItemQQptZLH_Def aultDomain_0?hash=item280305209494&_trksid=p3286.c0.m14&_trkparms=72%3A1205|66%3A2|65%3A12|39%3A1|240%3A13 18|301%3A1|293%3A1|294%3A50) which we are likely using

the thing's going to be used indoors, and we're not too concerned about wind gusts. We pondered over the dimensions for a while and i somewhat agree on the base size (i was thinking about 1m instead of 80cm), but the target's relatively light, and we do have two 8000mAh lead acids on the base...

Xmodgeek
Jan 25, 2009, 04:45 AM
Ah indoors, that should make it much easer and that's a neat radio, it has the relays and all built in.

Surnia
Jan 25, 2009, 09:16 PM
Ah indoors, that should make it much easer and that's a neat radio, it has the relays and all built in.

Yup, although we're still not sure about the airflow being enough or not. Does anyone have an idea of how much output we'd need to float this thing?