ISIRC10

Well, at around this time last year I started my previous project, so I figured why not start another one now? This time, using many of the lessons that I learned in the previous years, I will attempt to build a hovercraft. This will be a prototype that will serve as a proof-of-concept vehicle. It will be about 20" in length and about 10" in width. I will power it with a toy-grade RC unit that I got out of the trash for now - if it works then I will sink more money into it and use hobby grade controls. I have a centrifugal fan from a toy vacuum cleaner that I hope to use as a lift fan and I still am not sure what I want to use for propulsion. I want to keep this project as cheap as possible and use the materials/hardware that I already have. If this project is successful then I will add another weird vehicle to my collection - if not then I will have another learning experience under my belt.

I am basing my design off of the one on this website: www.model-hovercraft.com/2000tdx/2000tdx.html
As always, I will try to set aside time to take plenty of pictures
Please feel free to comment, your input is how I learn new techniques and methods. And if you see any noob mistakes, please tell me, I can garantee that I am younger than most of the people on this forum.

rcbif

Good luck with the hovercraft. I've made a few, but usually dont make them soldit enought to last a long time. For yours I'd suggest some type of shet foam depending on where you plan to run it. Here is a vid of one of mine.

http://www.youtube.com/watch?v=JkBlxeZAD3I

ISIRC10

The one that I am making will be made out of plywood - sturdy enough to compensate for my bad driving!
I will use pink insulation foam (1" thick) for floatation inside the main hull.

ISIRC10

Today I didn't get much done because I was trying to figure out how I would go about designing the hovercraft. I am still not sure about my final placement of everything so I guess I will just wing it and hope for the best.
I tested the centrifugal fan today and it didn't move as much air as I wanted so I will probably try to build my own, might even want to do a setup with twin lift fans.
On another note, I looked at the controller that I found in the trash and decided that the cracked plastic case had to go. Instead I started one out of wood. Estimated Work TIme: two days? This controller will be comfortable to hold and a bit less bulky, even though it may end up looking silly. So far I have used my router to create cavities for the 9v battery, control sticks, and circuit board. More updates to follow.

ISIRC10

Got more work on the radio done, it is finally beginning to look like what I want it to. I almost finished the top panel and have radiused the edges on the bottom half. There is a bit of sanding to do and some more carving/shaping on the top half. The areas where I have pencil outlines is where I will make depressions or bevels, which should make it a very comfortable grip in my hands.

All of this I have done with a router, drill press, and scroll saw. It just took a lot of planning out which areas I would have to router away first and which ones I could manage later (as you can see, I am not perfect and miscalculated my depth on the last picture, resulting in the hole under the left control stick. I will have to fix that some time). I should be done with basic shaping by tomorrow and go on to stain it. Then it is on to the main part of this project - the hovercraft! [8D]

asmithnc

Dude that is SOOOO sweet. Now thats thinking out of the box.

ISIRC10

LOL, thanks!

I figured that if I was going to go and make something original, then I was going to go overboard... At least it will look nicer then a hunk of black plastic!

ISIRC10

I haven't gotten much done these past two days as I have been really tired after work. (fixing boats isn't as fun as it seems when its 80 degrees or higher)
I still have not filled in the hole in my transmiter, however, I was able to carve out all of the areas that I wanted and now the transmiter is ergonomic, albeit a bit funky looking
From this point on, I will start working on the hovercraft, as all the cover needs now is final prep before I coat it with polyurethane. That can be done while I wait for glue to dry or I have other down-time.

Now the real fun begins! [8D]

crispyspa

That is one really cool TX!

jasperrc

I agree. A lot of work but very cool looking!

ISIRC10

Thanks guys, this IS a lot of work but I think that it is worth it (and I got a new router so this is a good way to test it out)

Now, the hovercraft...
will be 22 inches long, 10.5 inches wide, and about 2 inches tall (the base at least)
I have started to cut the pieces out of 5.4 millimeter thick plywood (this is the only stuff I have ready available to me ATM) Although the plywood is a bit thick and heavy, I plan to router out certain areas to make it lighter. I have done a test with one of the parts and have shaved off 2/3rds of its original weight while not compromising its strength and rigidity. For this build, I will make the two side assemblies first and then join them with the center sections, adding the skirt and fans later. Lastly, I will have to think of something to do for a cockpit/cabin.

Thanks for looking, hopefully you are enjoying this build as much as I am.

ISIRC10

Wasn't able to do much yesterday, as I went to the river (Delaware) with my family. I brought along my previous airboat, but when I got there, I remembered that my transmitter batteries died! [:@] DOH! So I just spent the time fishing, and it was a good day afterall.

However, before I left I did glue my side assemblies together and attached them to the main hull. I need to sand this and then glue the top piece in. Then I will make the two lift fans. In the end, I think that I may coat the bottom with polyurethane and paint the top, but I am still undecided... I think the grain on the wood is just too nice to cover up.
Once I have the fans and skirt done, it will be interesting to see whether it will hover or not (that is the main challenge of the project) - Then I will have to decide how to make it move forwards

ISIRC10

Well, I got some more done today... my soccer game was cancelled so I had some extra time for the project. The hull is now finished, and weighs in at about 10 ounces. This may be a bit heavy, but I am not concerned as hovercraft can carry quite a bit of weight on them without greatly diminishing performance. All of the joints on this hovercraft are held together by CA and then reinforced/sealed with epoxy. Sometimes I mix the epoxy with fine sawdust, which thickens it up and allows me to use it as a gap sealer as well. Tomorrow I will make the lift fans if I have time - if not, I will at least start them. I have also found a suitable material for the skirt/cushion, in the form of old "sweat pants" which are air tight and are pretty tough. That will be the next thing on my to-do list after the fans.

So far, this project has gone without a hitch... lets hope I didn't just jinx everything [8D]

ISIRC10

Update:
I have made twin fans for the hovercraft, which I will install shortly. They took about four hours to build (without curing time for the epoxy) and I am fairly happy with the amount of air that they move. Hopefully they will be able to inflate the skirt and lift the craft - if not, then I will end up with a normal prop doing the lifting and two overly complicated cooling fans! (So lets just hope they work!)

The centrifugal fans are modelled off the ones used in real hovercraft and can hold more backpressure than a normal propeller. They are two inches in diameter and 3/4" tall. I started with a 1/8" thick piece of oak which I cut into circles with my scroll saw. Then I cut the blades out of 1/32" aircraft grade plywood which I glued in with CA along the angled lines I marked previously. With that done, I sanded the blades so they would be of equal height and glued the top "doughnut" on. Then I drilled a hole in the center and press-fitted the fans onto the shaft of the 380 motors. I reinforced this connection with CA and epoxy. Then I ran the fans on a 3.6v power supply against a block of sandpaper to ballance the fans.

To make the shrouds, I wrapped a piece of 1/32 plywood around a 2" pvc pipe and glued the edges together. This formed perfect ducts for the lift fans. I capped them with balsa "doughnuts" and let the epoxy cure. Then, using a dremel tool with a diamond cutting wheel, I cut out slots which were then surrounded with 1/8" pine cutouts. These were rounded and covered with thin plywood, creating channels for the airflow. This will be ducted into the skirts. Lastly, I attached a semicircular backplate and placed the fan inside the shroud. When this had been glued, I attached sturdy motor mounts which secured the motors while allowing me to adjust the distances between the shroud and the fan. For all of this work, I really hope these fans will work - I will be very dissapointed if they don't.

jasperrc

I hope they do, but even if they don't you should be very happy with your crafstmanship. I would never attempt something like that without carefully laid out plans (laid out by someone else).

ISIRC10

Thanks, I know for one thing, that if these don't work, then I will put them into a handheld fan and use is to cool down when we go camping in during the summer.
There were some plans for the fans on the website (in fact, here they are)
[link]http://www.model-hovercraft.com/srn4mk2/srn4mk2fans.html[/link]
However, they were not very clear so I ended up making the fans spontaneously, that is without much planning and a lot of luck. They were going to be layed down horizintaly at first but then I decided (I don't know why) that it would be better to stand them up and had to change the duct design halfway throught the process. The first one too about three hours - the second took one. Some may think that this is a bad strategy for building and that everything should be planned out, but I just like to build and then see how everything fits together. It is just how I design things.

Oh, and by the way, taking these pictures sure is a pita sometimes... I may have to limit them as I barely have time to grab a camera in between glueing, cutting, and messing up.

ISIRC10

Well, I have glued the fans into the hovercraft, and they fit nicely. The ducts had a few gaps here and there but I filled those up with epoxy. Then I coated the bottom and electronics compartment with polyurethane and attached a few peices of pink insulation foam. They should descrease the amount of air needed to fill the skirt and allow it to fill faster. With the fans installed, I am beginning to worry - the fans don't seem to be moving as much air as I would like them to. The only way to find out whether they will work is to make the skirt and try it out.

About the controller/radio system - I smoked the "esc" control board today while testing the fans (she looks well done[X(])... the system was never meant to draw so many amps and something went poof and released its magic smoke. Time to put in the 4 channel tx and use hobby grade equipment. [sm=idea.gif] I am kinda glad that it smoked right now, and not when I had everything installed, as it would have been a headache to reinstall the controls. Now I will be able to control throttle, lift fans, steering, and an auxilary channel! A bow ramp perhaps?

Now I have to start making the skirt - I am not a tailor by a long shot, but I do know how to operate a sewing machine (Thanks Mom!) so things may get a bit ugly. I will try my best and see how things go. I will be using patterns on Mark Porter's website, scaled down to 1/2 size for the templates.

ISIRC10

I took a little vacation this weekend and my family visited some friends in conneticuit. It was quite fun and was a necessary break from this project. When we were there, we visited the mansions in Newport, the beach, and the aquarium. During my free time, I sketched what the hovercraft may look like when it is finished. I will post more progress on the build, I just didn't have time to do it before we left.

ISIRC10

Right before I left on Wednesday, I finished the sewing the skirt and glued it to the hull. While I was glueing it, I tested the fans and there didn't seem to be enough airflow and that got me worried. Nevertheless, I finished attaching it to the top plate of the hull and ran the fans once more. The craft rose to about five inches and then toppled sideways! That had to be one of the best moments of this build. I promptly attached (taped) the other side of the skirt to the bottom of the craft and tested it agian. The fans performed flawlessly! The skirt inflated and the craft could glide freely over hardwood floors and short carpet. Combined with a strong thrust fan, this hovercraft shoulf be able to traverse asphalt, sand, carpet, and even short grass. Here is a short vid, showing inflation and deflation times allong with a bit of gliding. There it was attached to a speed control so I was able to run it through a range of voltage. In the model, It will be running straight from the battery pack and will be controlled with a simple on-off switch and a servo.
[link]http://www.youtube.com/watch?v=NWKDLYdmMVc[/link]
Now I will see how well I can recreate my picture in the post above in real life. (they say it may look good on paper, but will it work? Who knows - there is only one way to find out!)

DONS BOAT WORKS

My Feedback: (3)

Nice vid.
I'm watching this build.

ISIRC10

Thanks Don!

This build is at a stage where pics may become scarce as there is a lot of one-off fitting and modelling.
I did not get much done after I came back from my trip (the drive wasn't very fun)
I was able to aquire a barbie doll for the driver (thanks to my little sis for being the donor) and decided that he needed to have his legs amputated for him to fit in the cockpit.
This project, with the newly thought-up top design is making me use the best of the space available as you can see. About 80% of the electronics are located in four square inches. I may come to regret this (with interference) but I can always move things... up to a certain point that is!

ISIRC10

OK, I have not posted here for some days now, as I have had to work a lot at the boat shop. People are coming in after the big weekend and all want their boats fixed at the same time and they don't seem to grasp the concept of a waiting line

Usualy I have about six hours to work on the hovercraft after work. These few days I have been so tired that I am only getting in about two a day.
Now for the update: I have made a removeable top for the craft out of plywood and 1/4" square pine rods (they were a pain to cut from the original 2x4). I have made the top removeable because I like to have access to the lift fans and r/c equipment when I am finished. On the removeable top section, I have also made a smaller hatch which is much easier to take off and provides quick access to the battery. The front console will feature a windsheild (plexiglass so it is bullet-proof ) and a steering wheel and guages. As of now, they still need to be made, allong with the rear console and thrust motor mount.

The duct for the thrust fan is made out of two peices of 1/32" birch ply sandwhiching 1/8" balsa strips. The ring is very sturdy so I have no worries about it being damaged. The 550 motor I am using for forward thrust may look familiar to some of you out there - It is the very same one I had in my first and second airboats, and is still running nicely. It will be spinning a 7x4 prop.

Hopefully I can get some more done on this project, I want to have a working hovercraft by Sunday, and a painted one by the end of next week.

ISIRC10

Got some more progress today, although I did have to stay and work overtime at my job.
The front console now has vents for the lift fan, now I need to make the rear cover. I am thinking of making it a tad lower than the front onein order to accomodate the motor hanging directly above it. That motor now has a shiny aluminum mount that I made out of a peice of 1/8" flat bar. It is strong and light. I also worked on the duct a little bit, beveling the outer diameter and installing vertical mounts for the triple rudders. They will also be beveled, and shouldn't block the airflow too much. I did a weight chech and she comes in at 3.5 pounds - with everything in her except for steering wheel and other negligable accesories.

Hopefully I can get the rudders set up tomorrow and have some test runs inside the house.Then it's off to paint! This project seems to wrapping up quite nicely and is coming together without any major hitches... that may be a bad thing...

At least I have learned to test my models for function prior to messing around with their form... kinda

DONS BOAT WORKS

My Feedback: (3)

"he needed to have his legs amputated"

Poor Ken!!!

Nice motor mount.

Don M.

ISIRC10

I can assure you he didn't feel a thing - and who needs legs when your butt is glued to a hovercraft?

Thanks about the motor mount... That was actualy version 2, the first one I tried to bend AFTER I drilled the holes and it snapped on me... Live and Learn