Mini air boat

[Basstronics]

Another project! Yippee!!!

Looking to build a mini air boat. I want to use my Mystery D2632 3000kv outrunner & 30A esc.

Im looking at 16" long 8" wide.

Trying to get an ideal prop size worked out so I know how to build it.

Going to work on the CAD model tonight some.

[damfurst]

I'll be interested to see how this goes. I think that you might only be able to run a 6 inch prop on your mystery motor. I have an Exceed 1800kv motor that anything over a 7" will heat the motor. I think I'm going to try and put it on the back of a extra Mini-C hull I have. Hope you post pics.

[sailr]

If it is a 26mm x 32mm outside dimensions, 3000KV, it should swing a 8 x 4.7 apc electric prop. My Storm outrunners that size but 1250KV will swing a 10 x 4.7 all day long on 3S lipo.

[Diegoboy]

For reference...

[bwells]

What about using an EDF (electric duct fan)? They are cheap and a lot safer. There was a build on here using one of these a while back.

[Chop]

For reference...

Hey! I have that boat now!!!

What about using an EDF (electric duct fan)? They are cheap and a lot safer. There was a build on here using one of these a while back.

Hey! I built that boat…
https://forums.offshoreelectrics.com/...ad.php?t=11893

[Basstronics]

I think I will stick to a prop.

10-4 on that 8" prop size. I want to order parts this weekend.

Its going to be a balsa-lite ply construction. I will end up putting a thin layer of fiberglass on the under side once I prove it in the pond.

CAD model coming soon.

[Basstronics]

I got the basic hull design done for now.

Going to order the prop adapter and a few props this weekend.

Attached is a PDF of the CAD file. Its still rough as far as the CAD goes. I have all the pieces figured out.

The boat will have a 2 degree included V- 178 degrees. There is also a 1 degree on the rear. So if you build the motor flat to the top and use the design as is, the motor will be 1 degree angle towards the sky.

Thoughts on these angles? I dont want to much lift but I would like to reduce drag- hopefully 1 degree is good enough.

[Chop]

In your section views you show the sides to be almost 90 degrees from the deck.
If you put the sides at about a 55 degree angle to the top deck the boat will slide around the corners rather that having to sharp edge to bite into it (making it more likely to tip).

[Basstronics]

Ah OK. I built this kind of like my lil swamp buggy...

I will put some angles to it tonight.

[Chop]

Ah OK.

Sorry, I'm no expert; build it the way you see fit.

I do see an obvious difference in the way the two boats (pictured in post #6) turn. The small one has straight sides and tips badly in turns; the large boat has angled sides and slides through them (the ducted fans lower C.O.G. helps with this too).

[sundog]

Yes, tipping. It would seem that 2 ducted fan units would do the same, only with a lower center of gravity. But I don't like the slow 'get up and go' in airboats. Was thinking of incorporating 2 ducted fan units on a jetboat (or a jet drive in a ducted fan boat) for quicker response.

[Basstronics]

Ok I got it done today and I got the parts printed out. Im going to start cutting wood now.

Attached is the overall then 3 sheets of 8.5" x 11" paper printouts. So if anyone else wants to build this they can.

I upgraded the wood to 3/32" Balsa. I added some 3/32" x 1/4" Balsa runners to help stiffen things up.

Will post pics later.

[Basstronics]

I just discovered the hard way that I bought 1/8" and 3/32" thick Balsa...

Dangit!

[Basstronics]

Update.

I need to build the motor structure now. Also have to figure out how I am going to do the rudder.

This is going to be a puller. Should I go with one rudder or two?

[Basstronics]

Is there any balance rule I need to be mindful of? Every airboat Ive seen is the engine way in the back...

Does the design of the uprights that hold the motor up make any difference? I can make them about 2" apart and straight up off the hull- or I could angle them so they are about 2" at the top and 4" at the bottom. Or will this factor in with 1 rudder vs 2 and the placement of those rudders?

[monojeff]

Not sure if you have ever seen this forum before but a lot of great info on here you can look through http://www.rcairboats.net/phpBB/index.php

Boat is looking

[Chop]

You've got a real nice start there!

I have 2 airboats, one with 1 rudder, and the other with 2. The profile of the single rudder is much bigger than the profile of the dual rudder boat.

I believe that the single (larger) rudder is less stable and more prone to influence from cross winds (tipping, blowing off course, plus a higher center of gravity). My personal opinion is to go with 2 smaller rudders.

Keep up the good work.

[Basstronics]

Ok Im gonna go with two rudders then. Gonna work on it tonight some more.

[Basstronics]

What a wicked fail today.

I decided to just see what this thing could do. So I mount the motor, put the spinner and the prop on. Go at it with 2S (this is a 3000kv motor).

And I fire it up. Got it going right. Get on it a little, man that thing was pulling some air... Then...





The mount was epoxied onto the uprights only. I have two layers of real light fiberglass down to the hull. One layer of glass over the hull deck/front lip. The uprights are 1/16" birch ply. Should I remove the mounts and do something different??? Or just reattach and add more wood behind it?


The motor is a total loss- good thing I have another.

[bwells]

The uprights are 1/16th or 1/8th? It looks to be 3 ply. Get an EDF and ditch that flyboy crap!

[Basstronics]

The uprights are 1/16" with two layers of super light glass cloth.

[bwells]

Can you still clean up the uprights and do the same thing and add 2 pieces of ply to the uprights, above and below the motor fastened front to back? That should hold it. Just a thought.

[Basstronics]

Well I need to go back to the drawing board on this.

Here is a list of props I bought- would like to use the larger props:
7x4.5E
6x5E
6x4E
8x5E
8x4E

I need to figure what the optimum RPM for these props are and get a motor/spinner setup to accommodate that. Im sure my boat size plays into all of this but getting info on something like this is much like pulling hens teeth.

Im probably going to have to cut my uprights off and start over on those. Thats OK to me. After seeing the output on this setup and I was quite shocked. After seeing the power after it ripped itself apart Im now scared.

I dont really want to do an EDF. I kinda wanted the prop look.

[bwells]

Can you chop off the uprights below the original mount and add to them and beef up the mount area? It looks as though the hull to upright connection was good and took the pressure.

[Chop]

Any progress on this lately??

It's been a fun build to watch.

[Basstronics]

Well I bought a new motor and some wood.

Just havent had the time or felt up to messing with it lately.

Heres the motor:
http://cgi.ebay.com/ws/eBayISAPI.dll...m=120449687355

Upringhys are going to made from 1/8" ply, with the motor mount forward keyed into the other wood so it cants just fly apart. Going to give it two layers of super light glass on both sides of both uprights. Somewhat considering a single upright also...

Gotta figure out a rudder scheme.

Lots of thinking to do.

[Basstronics]

Success finally!

My new motor mount structure has held up to a 6" and now a 7" prop. Not trying an 8" until on the water.

I bought the flex cable styled push rod. I have 1/2A mini horns. I had to special over some .032" micro clevis and ball links. not sure which I will end up using.

Today I fired it up. The 6" prop wouldnt pull it. The 7" would move it along the floor but not much. The battery isnt fully charged either...

Heres some pics. Not how I did the rudders. The piano wire on the actual rudder is like .015" undersized so it floats real good

[bwells]

Your vane hinges are top of the line, good job!

[SweetAccord]

HK has one now:

http://www.hobbyking.com/hobbyking/s...dProduct=17899