Hovercraft- Let the cutting begin!
 

My four-year experiment of modifying a factory built hovercraft, the saga continues. Last time out it operated on ice and land, but not enough lift for deep grass or to operate over water. It was a real hog on water, not quite out of the water, pushing it out of the way like a wounded animal or like primitive boat/displacement craft.

I could not figure out how to put my Roto-Zip back together, so I put one of the drill type cutters into my cordless drill and it worked! Not real clean, fast or with any high degree of accuracy, but it worked.

One of the things I did was to cushion my seat and kneepads. I used flat sheets of 1/2" pool noodle material.

The domed clear vinyl air splitter was adapted from a basement window cover, ran about $12.

I also covered the inside of the duct with sill sealer, to help absorb sound and to make a tighter clearance with the fan. I hope the adhesive I used stays on, if not I'll use mineral sprits to remove it.

I also used Great Stuff to build up a foam diverter at the bow. This should direct the tunnel air for lift, need to cut-form and sculpt it yet...............another project, will let flay as it.

I'm going to add a few additional clips to the diverter/splitter, maybe make the edge facing the fan more consistent.

The original craft used 33% of its power for lift; I'm guessing the current configuration is about 44%, so it will be a little slower.

Photos of work done Friday, Saturday and Sunday.

Will it fly?

http://forums.pelicanparts.com/uploa...1154965702.jpg http://forums.pelicanparts.com/uploa...1154965715.jpg http://forums.pelicanparts.com/uploa...1154965726.jpg http://forums.pelicanparts.com/uploa...1154965735.jpg http://forums.pelicanparts.com/uploa...1154965746.jpg http://forums.pelicanparts.com/uploa...1154965760.jpg

More.
http://forums.pelicanparts.com/uploa...1154965814.jpg http://forums.pelicanparts.com/uploa...1154965822.jpg http://forums.pelicanparts.com/uploa...1154965831.jpg http://forums.pelicanparts.com/uploa...1154965841.jpg http://forums.pelicanparts.com/uploa...1154965849.jpg

Sitting on hard fiberglass, just getting too old for that anymore.

Bring on the foam!:D

http://forums.pelicanparts.com/uploa...1154966473.jpg

Wow. Wish I lived close enough to come over and help. that looks like a fun project (when it's not my $ involved, anyway).

Good luck.

JP

Reminds me to put out a call for help.

Last year I tried my best to patch a small exhaust hole in the black metal using Map gas. Big freaking mess, wrong tool for the job, plus I suck at welding. Tim Hancock offered to do a quick weld on it if I swung by, but it's a several hour drive (out of state).

Anyone in S.E. Michigan want to give this a try?

I'D rather not yank it off and go to a local auto shop, don't want to catch my craft on fire either.

What do you think?

The protective/perforated heat shield bracket is easy to remove, but there are a half dozen connections holding it all on.

The hole is where another bracket used to attach to it, smaller than a quarter in size.

The yellow skirt material will melt and leave a hole if a spark gets on it. Take it all off ?

http://forums.pelicanparts.com/uploa...1154971001.jpg

EDIT:
I had a local Auto repair shop weld a patch on the exhaust pipe/muffler. I then painted with a combination of black 1,200 degree paint and yellow 500 degree paint (red letters said "HOT"). The 500 degree paint blistered and turned an ugly brown in under 10 minutes of operation. Guess the muffler runs way hotter than 500 degrees, live and learn.

Re: Hovercraft- Let the cutting begin!
 

UPDATE: LABOR DAY 2006
I let this project sit for almost two months, but have the old 911 running pretty good.

To answer my own question, it did fly.

However the saga continues as it did not do very well.

The problem is two fold, I need both additional lift and thrust out of my old craft to make the new experimental skirt work.

My goal never was efficiency or performance for that matter. My goal was increased obstacle clearance and stability. I can still reach my goal, but have to toss more into the pot to make it go.

There are descriptions in the upper right hand corner of the webpage links which describes what I'm facing and my thoughts on how to deal with it all.

I just took a saw to the lower front bow of the craft, except for the aluminum supports it's 100% open now. I just pinched the air flow too much before it could enter the plenum under the craft.

I will also Gorilla-Tape up some of the side bag feed holes so more lift air actually gets under the craft. The craft is still too stable and will not lean into a banking turn. I don't need all that side pressure in the bags, I need a real air gap to reduce friction.

The videos..........

Part 1:
http://video.google.com/videoplay?docid=8306791101923106301&hl=en

Part 2:
http://video.google.com/videoplay?docid=-7414948022879099026

Part 3:
http://video.google.com/videoplay?docid=1013029571331310870

Part 4:
http://video.google.com/videoplay?docid=6657780685702543190

.................and the journey continues.:)

WOW, that thing is cool.

Thanks, it can be fun, it can also be a pain.

As promised more hacking and cutting photos.

Thinking of adding more surrounding supports (aluminum). I have to get the air flow sculpted much better than it is now at the bow, just starting the process.

I thought I only had a couple air holes each inflated sponson side to seal up. I can see where I need to seal up many holes, don't need the air in the sides, need to get it out the front and under the craft.

Tweeking may not cut it, but it will help. I'm more or less set on replacing the drive/lift fan. Plastic gets old and breaks down with age, probably a good thing to replace every 17 years, right?

I mean car tires should be replaced every six years no matter how many miles on them, right?

http://forums.pelicanparts.com/uploa...1157463715.jpg http://forums.pelicanparts.com/uploa...1157463733.jpg http://forums.pelicanparts.com/uploa...1157463742.jpg http://forums.pelicanparts.com/uploa...1157463750.jpg http://forums.pelicanparts.com/uploa...1157463759.jpg http://forums.pelicanparts.com/uploa...1157463769.jpg

A few more pictures.
http://forums.pelicanparts.com/uploa...1157463844.jpg http://forums.pelicanparts.com/uploa...1157463855.jpg http://forums.pelicanparts.com/uploa...1157463866.jpg http://forums.pelicanparts.com/uploa...1157463876.jpg

So was that a kit or did you build it from stuff you had???? Why not just get a bigger blower to force more air into the skirt and under the craft??

Factory built 1989 Scat II, 35 hp, 30 inch fan.

Bigger blower can mean three things:

1. Improved replacement fan.

2. Bigger engine with better fan, and more blades and higher degrees of attack.

3. Add a dedicated lift engine and fan, and convert the rear fan into thrust only...........aka "Air Commander" hovercraft style.

More into the pot anyway I look at it.:cool:

The challenge at this point will be getting it to work without major changes. There is a slight chance I can tweek it and get it to work. Then all I have to do is to get it to work BETTER.:)

Hey George,
I have about got mine back together, ( SCAT 1 )
I'm dropping in a Rotax twin Cylinder water cooled rotary valve 536 pulled from a Ski Doo snowmobile. I got my motor mounts finished. All I need now is a little time to finish things up and run the lines for the radiators.

The Dark Side water cooled it is.

:D

http://35heures.blog.lemonde.fr/phot...rized/yoda.jpg

I'll never be able to keep up with you now.

Get good at it and you will do good when racing it.

Air distribution is unequal, looking at adding a foil like scoop to balance it out.

What do you think?

http://forums.pelicanparts.com/uploa...1157967526.jpg

UPDATE 09-25-2006

Took it out for a third test flight using the heavy yellow skirt fabric. This is the second time out on water, the first time with video of the stren wake condition.

Below is a sketch to show the design and proposed fix to the design flaw(s).............which may be more than I'm attempting to fix at this time. One problem and one fix at a time, just so I can equate results, actions and reactions.

http://www.hoverclubofamerica.org/fo...81_6_42848.jpg

Links to three videos, the last video is of most importance if you have time to click just one. The hovercraft just about leaps into the water just to encounter massive drag at the stern moments later. Watch for the vortex of water billowing in the form of wake between the twin tails.

Part 1:
http://video.google.com/videoplay?docid=2874026733268022464

Part 2:
http://video.google.com/videoplay?docid=5341781496606431296

Part 3:
http://video.google.com/videoplay?docid=2182246473369429912

During water operation the partial stern bag which is fed supply air from pressure under the craft, has been found to act like a drag chute under real life conditions. So much for theory alone. A large central drail hole was unable to get the water out fast enough. I don't want the water getting in there at all, need to rethink this portion of the design - again.

Items in blue marker are proposed changes which have been on my mind since I started the project. It's time I made these changes while it's still warm enough to work outside in Michigan.

What do you think?

The sail like splitter I installed worked very well. Almost too well, I now have slightly more air coming up to the starboard supply air lift hole than to the port side supply air lift hole. It was once double the air on the port side prior to the diverter/splitter modification.

The craft had more lift and more thrust than last time out. This improved on-land performance, but was you can tell at-sea performance is still lacking.

I could not turn into the wind, nor with the wind, so I went across the lake and used the shore to do a 180 degree turn. I then ran out of gas 2/3 rd's of the way back, one guy (DNR) got my spare gas can, but his boat was too small to tow me. On the way back another but much larger boat gave me a tow as I was not quite up on cushion with the drag chute holding me back - made lots of spay though.

Perhaps if anyone ever wants to develop a sea anchor or brake drag chute for hovercraft they will look up my little experiment here. :D

I'm learning a lot, so I guess that means I'm having fun.:D

Wow, that thing is really moving now

In it's current condition it will perform great on ice. The heavy skirt material should hold up well against that abuse. However once I hit the water the rear bag acted as a drag chute or anchor. The fix is pretty easy, having the time to tinker with it is not so easy.

So many toys, so little time.:D

UPDATE:
Ford Lake, Sunday October 08, 2006.

Took it out three or four times into the lake, same result everytime. Gets out there, starts to slow down, nose starts pushing water.

From what I can figure the lower front bow skirt drape edge where the pool noodle is, is being sucked down.

The bow drape going straight across, and the pool noodle addition were not my first configuration choices for this craft. I wanted to slope it inward like a boat but all the extra cutting and fitting would of taken more time than I wanted to spend this spring.

Worked great in the parking lot, and getting it on the trailer was pretty easy to.

I think it work just fine on Gun Lake this winter. Come spring time, I'm doing some major modifications for water operation. It's going to look like a boat by the time I'm through with it.

The sharp lower tail/sponson corners with their weep holes are catching water too. You can see it in the second video pretty clearly (and in the parking lot video). If I can shape it like a canoe, that's what I'm going to do.

6 Videos:

http://www.youtube.com/watch?v=QQkzh0Yd0qE

http://www.youtube.com/watch?v=Jq6yx7061lI

http://www.youtube.com/watch?v=0S8rW3cmhT0

http://www.youtube.com/watch?v=_eghLJ0dU0w

http://www.youtube.com/watch?v=p7YHk0hq7Ek

http://www.youtube.com/watch?v=NNUioMLU1_A

How much weight has been added by your mods, and are you calculating that into your power requirements?

Why don't you just buy a factory skirt, they work fine. I must be missing something???