Hovercraft

Be Patient..  This is a pretty big page!

Welcome to my hovercraft page. I'm am currently in the process of building a UH-10F hovercraft.  Since this is supposed to be the easy one,  I wanted to try it first before I pour a ton of money into a real fancy one (like the UH-19)! 

(click on the pictures to see a bigger version)

(6-5-01) Here's a picture of the completed hull: 

You can see in the background the workbench that I built so I could start this project.  Also, you'll notice the fan running since in Texas, during the summer, it gets mighty hot!  Why do I always do these projects during the summer!?  

If you've built a UH-10F before, you'll notice that I've got an extra sheet of plywood on the bottom.  Well, when the instructions call for lots of weights to be placed on the hovercraft when gluing the foam to the top-deck, they are not kidding!  I didn't get a very good  bond, so I epoxied another piece of plywood to the bottom for structural reasons.  Also, if I do happen to hit anything while hovering around, it'll keep my foam from being ripped to pieces.

(6-10-01)  The plywood for the thrust duct is completed and the thrust duct foam is in progress.

  Front view of UH-10F with plywood portion of thrust duct sitting in lift air duct as a temporary storage location.

  Rear view of the same.

Duct foam getting ready to be fiber-glassed and shaped.

Making the plywood disks was not as easy as I thought it would be.  I traced out the circle and then used a jigsaw to cut as close the line as I though prudent.  Then, I used a belt sander to clean up the circle.  However, I never was able to really get an exact circle.  Hopefully, it will be good enough.  Next time, I'm going to try something different.

Also,  getting the plywood to wrap around the disk was a bit tricky.  It turns out that one end of the plywood was actually thicker than 1/8th of an inch for some reason.  It took some creative gluing and strapping work to get it secured in place.

Next, shaping the foam and attaching it to the thrust duct!  

(7-1-01)

Since I had to run out of the country on a business trip for the last two weeks, not much work has taken place on the hovercraft.  However, here is a picture of what I did on the weekend while I was away.

 

(7-26-01)

Here's a picture of the thrust duct attached to the hull:

And a side view with the side air box pieces installed.

The thrust duct took way more time than I planned!  First, the UH-10F plans are not correct.  It says to fiberglass one side of the foam and then sand/cut the airfoil shape.  This works fine until you try to bend it around the plywood part of the duct!  Because you are not only bending the foam around a circle, but also at an angle (angle side of foam goes on to the plywood), there is no way in the world that it will go around correctly!  I ended up cutting a ton of grooves all the way through the foam and through the fiberglass, so that I could get it mounted.  Once I finally got it attached to the plywood, I had to go and fill in all the cuts and all the indentions that I made while trying to force the foam on the plywood.  It took two weeks of glassing and molding to even get a poor-to-OK looking duct.

From now on, I'm only looking to the plans for suggestions and overall directions.  The actual detailed instructions aren't all that correct.  I guess any blueprints that cost only $20 have a right to be pretty much wrong!

(8-4-01)

Front view with air box completely done and with the side cockpit panels installed.  The engine and engine-mount supports are just laying in place.  I laid them in place to make the picture more impressive! :-)

Rear view picture of the same.

Well, the air box is completed.  It took a little bit of work, but it wasn't too bad.  I still need to sand it and pretty it up before painting.  Also, I need to finish cleaning up right in front of the duct where the expanding foam was used to glue the duct to the hull.  I think that I'm going to just smooth the foam out from the duct to the hull and fiberglass over the whole thing to kind of blend it all together.

Also, I installed the engine mount and the cockpit side panels today.  I didn't use the same type of center engine support that the plans called for.  I had a piece of 2"x6" exterior decking material laying around that I decided to use.  It's quite a bit more sturdy and most important, free!

For the actual engine mount, I glued two pieces of plywood together with a sheet of aluminum in between.  The two sheets gave the proper thickness to the mount and I figure the aluminum will add a bit of safety and strength.

(8-23-01)

Things have progressing slowly since I've been out of town quite a bit.  However, quite a bit of sanding and Bondo work has been done to smooth some of the rough patches.  I also attached the engine for a test run a few days ago. Even at just idle speed, there is a ton of air coming out the back end!

I started the rudder and assemblies this week, but I don't have any pictures as of yet.

(9-9-01)

Ok, after a long time with no pictures (working on the hovercraft took higher priority), I now have a bunch of pictures to show.

      

You can see from these two pictures where I used Bondo to smooth out certain areas of the hovercraft.  You can also see the rudder mounting blocks.

    

Here you can see the rudders after I primed them so I could see the imperfections. The other picture shows the upper rudder mounting pin.  The plans call for the rudder pin to be permanently mounted in the rudder.  However, I wanted the ability to remove/replace the rudders without tearing apart the hovercraft, so I made them removable.  To do this, I first drilled out the 3/4" hole in the top of the rudder.  I then took the upper rudder mounting pin and covered it with plastic. Next, I took a large piece of fiberglass cloth and wrapped it around the mounting pin.  Then, I covered the fiberglass with epoxy resin and shoved the whole thing down into the 3/4" hole in the top of the rudder.  After the epoxy resin dried, I pulled the mounting pin (and the plastic) out of the hole.  I now had a waterproof hole in the top of the rudder to stick the mounting pin into. The second picture shows the hole and cotter pin that I put into the mounting pin to keep it from falling out during operation.

          

Painting day finally arrived!  I took the hovercraft to East Texas so my Father could use his airless spray rig to paint the hovercraft.  We had a couple of problems with the spray nozzle, but other than that, it turned out quite nice.  We put an oil based exterior primer on the entire hovercraft and them used exterior latex paint for the top coat.  The rudders are sitting on a 2"x4" that we drilled two holes in so that the rudders would stay standing up.

          

The first two pictures are the steering stick.  I'm not using the pulley method for steering like the plans say, since every other UH-10F web site says that pulley method is pretty useless (again, what do you expect for $20 blueprints?!)  I'm using bicycle brake cable for the steering.  On the steering stick, I drilled a large hole, a smaller hole, and then used a jigsaw to connect the two holes together.  This way, the big lead knob on the end of the brake cable goes in the big hole and slides down to the little hole via the slit.  Once the hose clap is installed, the cable cannot come out of the steering stick.  The brake cable outer sheathing is 'braked' by a little tiny eye bolt that only allows the inner cable to go through.  The outer cable is also held in place by staples.  The throttle is simply a brake handle off of a bike.  The local bike shop was nice enough to give that to me for free.

The other two pictures show the top rudder mounting pin and the other end of the steering system.  I ended up switching to 1/2" EMT for the upper rudder pin since when I was bringing the hovercraft home from being painted, I had to drive through a thunderstorm that soaked the entire hovercraft and caused the upper rudder mounting arm to swell a little bit.  This made the original wooden pins too large to get through the hole.  The rudder end of the steering system is almost the same as the connection to the steering stick (eyebolt and staples), however I added a spring to help keep the steering stick upright when the engine is not running and there is a turnbuckle to adjust the tension of the steering cable.

       

Here is the hovercraft back sitting on four Home Depot buckets getting ready for the installation of the skirt.  I cut the skirt material in half to get the required 30" width, but I haven't actually cut the side pieces as of yet.

(9-30-01)

Ok! The hovercraft is done!  I finished up the skirt late on Saturday in anticipation of going out to the lake on Sunday afternoon with my buddy.  The skirt was a chore to do since I don't have a sewing machine, so I had to do all the corner sewing by hand.  I also mounted my mini-tach and did a little paint touch up.  Here are some pictures of the hovercraft at the shore and one while I'm hovering around.

    

However, disaster struck after only a few minutes of hovering!  When I first tested the hovercraft on my driveway, to see if it would actually lift me off the ground, it seemed to work perfect.  But, when I got to the lake it seemed to be vastly underpowered.  It couldn't lift me off the ground when I was on the grass.  When I got on the water it seemed to work fine, except that it was really slow and was hard to turn.  Then I looked at my tachometer and realized that I couldn't get more than 3100 RPM out of the engine (instead of the recommended 3600-3800 max).  Then, I hit the wake of a jet ski and the hovercraft started to tip to one side. Water came up the one side of the hovercraft and hit the prop, which de-laminated and grabbed the chicken wire guard and wrapped it around the engine shaft.

So, needless to say, that was the end of the day's hovering.  Luckily, the damage was minimal, so for the first trial run, it wasn't that big of a deal.  A little touch up paint, a little work to the prop, and maybe a new fan guard and I'll be back to where I started.  I'll then just have to figure out why I'm getting so little power.

(1-20-02)

Well, I don't have any more pictures right now, but I did get the UH-10F cleaned up.  I took it to my parents house in East Texas (old house since they just moved to Detroit) and let my Dad fly it around their huge concrete driveway.  It still doesn't want to turn very well and still won't lift me up when it's on grass.  However, I think the lift problem is with my prop.  Evidently, UH sells two types of props. One is a quieter one with not as much lift and the other one is the low pitch (hence higher RPM and noise) made for when you really need the extra static pressure under the craft.  Also, I'm going to extend the rudders a little bit to help out with the steering.  Right now the craft is stored under a big tarp on my trailer until spring comes back around.

(9-2-02)

Since I moved in February and have had to spend most of my time on the house, I haven't played with the hovercraft much.  I still need to order the new prop.

(12-24-02)

Still haven't ordered the new prop yet.  I did take it out in October and extended the rudders with some aluminum sheets and it made the turning much easier.  However, it only works on concrete for me and only barely on the grass for my much lighter wife.

(3/10/03)

It WORKS!!!  One of the neighborhood teenagers that I was paying to help me do some landscaping, looked at the UH-10F and realized the problem within 30secs.  The crazy prop was on backwards!  I somehow completely forgot all of my physics and mounted the thing so that the trailing edge was cutting the air.  It blew air in the right direction (just like an airplane wing will fly backwards if given enough thrust), but the drag was so great that the RPM's could never get up very high enough to do anything.

So, Saturday evening and Sunday afternoon, we drove it around the house and in the pasture (I had to mow the tall grass down to make it work).  Hopefully, I can get some video posted with it running around.

I feel better now that all that hard work that I put into the thing is actually paying off with some fun!

With some actual use on the craft, I'm seeing some areas that need some improvement and repair.  The abuse of learning how to drive the thing, especially in my yard where I have just planted 30 trees, has caused a few seams in the front cab area to come loose.  I'll have to fiberglass and glue them together a bit better.

3/21/03

I now have a video of my wife driving the hovercraft around!