| T.R | Title | User | Personal
Name | Date | Lines |
|---|
| 348.2 | | ARNOLD::TACKETT | | Mon Nov 02 1987 14:18 | 2 |
| Thanks Dan I'll look into that!
Mike
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| 348.3 | 1-hour hovercraft (no balsa needed!) | 38821::YERAZUNIS | Snowstorm Canoeist | Tue Nov 24 1987 17:45 | 68 |
| I built one VERY simple hovercraft in jr. high school:
Cut a 18" diameter circle of thin aluminum. Cut a 6.5" hole in the
middle of it. Cut a strip of the thin aluminum 4.5" high by 21" long,
and roll this into a stubby cylinder. Expand the cylinder to just fit
snugly into the 6.5" hole. Rivet it at this diameter (pop-rivets
are fine. Use the smallest they make).
Remove the cylinder, and cut short (1/4") slots every 1/2" around
one end, so that you now have a whole slew of little tabs. Bend
half of the tabs outward (alternating bent and unbent). Slide the
cylinder into the disk, unbent tabs first, and bend the unbent tabs
outwards, locking the cylinder into the disk. That's the main part
of the hovercraft!
You now have something that looks like a very wide-brimmed top hat,
with no top! This is as it should be. Now, cut a thicker (like .040
or .060) strip of aluminum, 1" by 8", and rivet it with your handy pop
riveter (and the tiny aluminum rivets) right across the lower apeture
of the cylinder. Drill this strip to mount an integral fuel-tank .049
and bolt the engine in. The engine should be entirely within the
cylinder, facing upwards. A <gaaakk> Cox spring rewind starter makes
the thing finger-startable. Can you say "Cheap ducted fan?" A 6x3
nylon prop is the order of the day here.
You now need the "skirt" that keeps the air in. I used soft vinyl,
though cheap is important here. Coated tent nylon would probably
work too. Epoxy a 3" wide strip of this stuff to the outside edge
of the big disk, so the cloth hangs down. If you leave a slot in
the skirt, it will propel itself around on the resulting air jet.
Even without the slot, it really boogies. It's essentially
frictionless on even rough pavement, and it WILL start sliding down even
the gentlest hill (it'll float down a hill that a basketball won't
even roll down).
I built one of these critters when I was about 13. It's still hanging
from the ceiling at my parents place. That aluminum-and-rivets
construction really stands up to abuse!
By the way, hovercraft make worse dust storms than helicopters.
They can also carry a much higher load.
---------------------
I've seen plans for hovercraft (even models) that used a more advanced
skirting system: retro-deflected air jets. They worked like this..
| |
| ~~~~~~~~ | fan
| MMM |
|--------------- ----------------|
\ /
\ \---------------------------------/ /
\ \ / /
-----------ground------dirt-------pavement------rocks------ants-----
The idea here is that air from the fan squirts inward, forming a
curtain that keeps the increase in pressure inside.
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| 348.4 | Ahem. | 38821::YERAZUNIS | Snowstorm Canoeist | Tue Nov 24 1987 17:48 | 7 |
| I should mention that the .-1 hovercraft works with the skirt lowest,
then the large disk, then the cylinder-and-engine topmost! It'll
dig a hole the other way 'round....
At least you don't need a pusher-style prop or a chopper-type
fan-cooled engine...
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| 348.6 | VERRRRY CAREFULLY....!! | GHANI::CASEYA | THE DESERT RAT (I-RC-AV8) | Wed Nov 25 1987 12:32 | 1 |
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| 348.7 | Hovercraft don't $uck they b10w | AKOV11::CAVANAGH | We don't need no stinkin badges! | Wed Nov 25 1987 14:05 | 34 |
| Instead of leaving a small slot in the skirt to allow air out, how about
a tube that is connected up like a rudder? By moving the tube to the side
you could cause a little spin in the craft and then straighten the tube
for forward motion.
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^ - -
==== O -
v - -
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Bad drawing but I hope you get the idea....
Jim
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| 348.8 | It's a lot more bovver wiv an hovver | RDGENG::NODDLE | Keith Noddle REO2-G/D8 830-3953 | Thu Nov 26 1987 08:54 | 26 |
| Funnily enough, I built a hovercraft when I was thirteen too - reckon
it's part of puberty?? I'd just finished reading a book on Christopher
Cockrell and was fired with enthusiasm to build and play with something
R/C in my own backyard. I didn't have the same luck however:
(i) It hovered but wouldn't move forwards even with holes
drilled in the back of the skirt (mine was made of plywood).
(ii) I tried to R/C it using my old Single Channel gear.
I used the principle of forward motion creating enough
slipstream to make a BIG rudder effective. Didn't work
either as it never went forwards at all!
(iii) The cylinder head of my trusty Enya 09 had never been
the same since - unburnt fuel from the carb seems to
caramelise on the head! and despite everything, the
engine gets HOT in the enclosure.
(iv) Lastly (and worst) the ariel lead from the RX dropped
into the fan - what a mess!
At this point I gave up.
I am of the opinion that the design shown in a previous reply which
involved an inner baffle (like some of the "real" ones) to create a
"curtain" of air would be the best - but then, given my success(?)
record, who am I to speak?
Keith.
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| 348.9 | Mild green Fairy hover | IOSG::CARLIN | Just discovered /personal=... | Wed Feb 17 1988 17:31 | 26 |
| Re .8
Funny you should say that. On reading it I was fired with nostalgia
for the hovercraft I built when I was 14 (I won't say how long ago).
If nothing else it was simple:
Take 1 plastic washing-up bowl
Cut round approx 2" from base
Invert base, cut hole in centre to clear 8" prop
Make two vertical cuts in remainder and rejoin to make a cylinder
with 8" internal diameter
Fix to base with plastic solvent
Fix in bearers and engine (ED 2 cc comp special, useless engine
but I've still got it, hadn't the heart to throw it away, perhaps
it's got antique roadshow value. It did work well pointing down
though)
Apart from the contra-rotation which built up it worked very well.
You could give it a slight push and it would easily cross a large
playground. It always used to surprise me that the leading edge
didn't dig in, even when you gave it a really hard push.
Sorry, I've just remembered the name of the notesfile.
RC? You must be joking, transistors had only just been invented.
Dick
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