Andersean

I am in the design phase of an rc hovercraft(LCAC) and i was told to post something in this forum about it. It will be 24"x13" and powered by edf fan units from a Guanli A-10 that i crashed. if anyone can give me some advice on the skirt and how to inflate it. i will post pics later on my design. i would post my sketchup work but my computer wont let me i will be doing a sketch on graph paper and i will scan it with my printer and upload.

ISIRC10

What you can do is export some views in jpg format... somewhere on the "file" menu.

subscribed, and watching progress! What advice do you want with the skirt?

Andersean

Materials(cheap) shape(finger and bag) inflation methods

Andersean

How do you insert pics in a response like this?

Andersean

Ok i figured it out. here they are

ISIRC10

okay, skirts... lets see...

Materials - anything that is relatively tough, waterproof, and holds air... for mine I used fabric from an old pair of athletic pants...
Cheap - use a heavy duty trash bag... you know the contractor bags?
Shape - while finger and bag is nice, it is complicated... just do a simple bag design, get the plans from the website I linked previously.
Inflation - I have tried almost everything short of a miniature jet... the best was a normal prop, about 7" in diameter in a close fitting duct

After seeing your design, base the bottom half of your build off of griffon 2000 plans so you can use the skirt layouts. However, instead of using plywood and balsa, use 2"-3" insulation foam board... the pink stuff. That saves a lot of money and is easy to work with. carve that to the general shape of the plans, should look like this:
___
( ___ ) from the top view. Then you cut out a hole in the front of the slab for your lift duct and route two canals for feeding the skirt. Put the skirt togethter with duct or gorilla tape, and then tape it to the sides of the slab... you have a hovercraft. Now just make the deck whatever you wish... an LCAC in your case.

ISIRC10

heck, If you don't want to mess with the curved surfaces of the deck on the griffon 2000, just have a foam square... that makes your skirts even easier to make!

Andersean

OK, i have some styrofoam 1'8"x1'3.5"x1/2" which i will put in the skirt for floatation instead of insulation foam. or you can draw a pic or youcan make a sketchup model and take a screenshot (like i did)of what you mean

Andersean

Someone is willing to give me a deflated excercise ball would that be a suitible skirt material?

ISIRC10

depends on how flexible the rubber is, whether the contours of its original spherical shape will interfere with making your rectangular pannels, and how you will join them together... but I think you can make it work! I will post back in a bit with some sketchup models... If you wish, Pm me your email so I can send you the skb files so you can look at them in sketchup.

Andersean

would you advise me in using construction garbage bags, an old shirt, or a painting drop cloth. im thinking garbage bag, because shirts get heavy when wet and drop cloths even more so

Andersean

Here is a cutaway of the port side of my hovercraft.

Andersean

I just looked at the setup that nitroplanes uses for the brushless a-10 and to upgrade i would need $118.80......i have 1/5 that...

Andersean

How do you waterproof brushed motors supposing they arent already waterproof. in case my hovercraft fails and i decide to build a boat with the like such

cowana

An EDF won't run under water. Well, it will, but you'll be lucky to get much more than 100rpm from it, and your boat will move at a very slow speed.

The reason EDFs work so well is that air is not very viscous - stick it in water and you'll get a really slow 'jet' of water.

Best to stick to a small two blade prop if you want to go propeller drive.

A

gulfstreamI

A company called Kinetics made an LCAC hovercraft years ago. I still have mine stored in a box after using it for three years both in winter and summer. It has dual lifter fans and dual thrusters. The lifter fans are 540 sized brushed motors and so are the thrusters. The skirt material is made of a very thin & soft nylon fabric that's similar to that of an umbrella. For flotation incase the batteries die out before the LCAC gets ashore a 1" thick styrofoam material was sandwiched in between the lexan/polycarbonate deck and fiber board material that also held the skirt.

You can find running pics of it here in an old thread called : "Pics of your airboat".

Andersean

Gulfstream can you give me a url for the thread so i canfind it?

gulfstreamI

Some pics of the Kinetics Hovercraft manual

Andersean

Do you have dimensions like length width shirt height overall height

gulfstreamI

The LCAC's total length is 29" from bow to stern and 14" in width. The skirt was prefabricated by Kinetics Inc. which made these hovercafts.

Andersean

hmmmm...mine is going to be 24 bow to stern and 13 in width but i dont know how much fabric to cut because i dont have a guideline or general size to follow; how deep is the skirt inflated?

gulfstreamI

I'm pretty sure the skirt was about 2" in height fully inflated. I remember this material was also similar to those "windbreaker" jackets that were water resistant.

Andersean

I found a dead umbrella and i think i will use that as my skirt material there are no rips just broken metal spars, and it is waterproof as well as very light i have a general idea of how i wil put it together, and inflate it. It will be cut into four to six pieces which will be sewn together and segmented into four seperate air pockets which will be inflated by the centrifugal fans. there will also be holes on the inside so that air can get underneath and keep it hovering.

gulfstreamI

Bottom view of the skirt material in relation to the lifter fans. About 50% of the lifter fans airflow is directed at the skirt (thru openings on both sides) to inflate it and the remaining 50% is expelled as lift. I found no other holes.

Andersean

Yeah i found a problem with the holes(more work) so i will probably just do that except im using centrifugal fans so 2 will provide inflation and 2 will provide the cuision of air that escapes underneath the skirt, btw i have the plans for the skirt panels i just made what i want the skirt to look like and flattened it out(long process) here is the hovercraft and the skirt panels