PDA

View Full Version : Hover Project



Big K
31 Mar 10,, 11:09
i am starting to build a homemade RC Hovercraft.

approx. 50-65cm long frame.

i ll use a 90mm ducted fan with a 1800kv brushless for lift,

2x 60-70mm ducted fans for thrust.

i ll use a bag+finger skirt combo made from kite fabric

what are your thoughts?

Andrey Egorov
01 Apr 10,, 14:40
Judging on the scheme pressure losses between fans and skirt will be huge. I'd take a couple of smaller fans to propel the craft and the bigger one to directly inflate the skirt.

omon
01 Apr 10,, 15:46
i don't see how you will get air under the skirt, i see you inflating the skirt like a donut, , but no air actually lifting the craft.
i also don't see why, you even need skirt itself inflated, cuz unless you drive this thing on smooth surface or water, you'll loose all air cushion as inflated skirt hits first obstacle, like a stone for example
am i missing something?

Andrey Egorov
01 Apr 10,, 16:10
Inflated skirt will recover its shape after any collision not strong enough to rip it into pieces. Still the scheme itself is overly complicated to me.

I'd suggest a skirt consiting of set oh hoses sewn together side by side. Air will get inside the skirt through hoses.

Big K
01 Apr 10,, 16:36
my main problem is if 2xtandem fans will be any good for air pressure.

the skirt design will be like a bag+finger skirt.


James' Hovercraft Site: How a Hovercraft Works (http://www.jameshovercraft.co.uk/hover/html/hovercraft_concept_theory.htm#momcurt)


http://www.jameshovercraft.co.uk/hover/images/theory/momentum_curtain_principles.png

here you can see the same principle with my drawing.

Big K
01 Apr 10,, 16:53
Ian's Astounding Hovercraft (http://www.astounding.org.uk/ian/hovercraft/mark1.html)

Mark's Model Hovercraft - Home (http://www.model-hovercraft.com/index.html)

very good projects about RC Hovercraft.

see there are 2 main types about lift&thrust combos.

first one is this:http://anggun3.files.wordpress.com/2008/05/hovercraft.jpg

big, heavy, that needs a separate lift engine and thrust fans,

second is this: http://www.rhevans.co.uk/hovercraft.jpg

light, fast, can use its only engines 1/3 power for lifting and the rest for going forward.


my design philosphy was to create a high power/weight ratio craft able to hover without going forward. also i do not want to build a conventional version because i did it 2 times in smaller scales.

thats why i wonder if 2 horisontally tandem fans would create a powerful air flow.

then that air flow would be directed by simple servo powered panels through the lift or lift+thrust.

Andrey Egorov
01 Apr 10,, 17:22
Since you use two motors anyway there's no obstacles to make the weaker one to maintain the the skirt and another one - twice more powerful - to move the whole craft. You can control them independently.

From my experience in computer cooling tandem fans are equal to single one, they just producing more noise.

On servo panels - I always thought that turning the whole propeller-motor unit is more effective. There's big dead weight in your design, I think. All these airducts and panels. Could you please show your idea how air will flow inside?