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Help designing/scratch building small airboat

Old 04-22-2016, 05:59 PM
  #1  
golf4two
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Default Help designing/scratch building small airboat

First, I'm an airplane guy...not much experience with boats except as a kid (which was many, many years (decades) ago!). I have over 25 years experience designing, building and flying aircraft but know nothing about boats except that most are designed to float and "motigate" across the water.

I have the electronics and motor from a "foamy" airplane that I won and didn't like very much that I'd like to put to use. Lots of ponds and a couple of lakes nearby and a kind of long drive to the flying field so I thought it might be fun to build a little air boat to piddle with. Here's what I have on hand:

(All EFlite stuff from a flying wing that was quite speedy)
BL180 2500 KV motor
4.5" pusher prop

8 AMP EFLA 7200 ESC

2 cell 450 MA 30C Lipo

A couple of micro servos

FUTABA 2.4 GHZ aircraft radio (I assume that would be OK).

Building materials would be balsa, ply, foam and fiberglass. I'm comfortable with all three.

My questions are many, but lets start with:
1. What basic dimensions should I shoot for given the above power setup?
(It needn't be a speedy little thing, just some fun at the airfield lake.)
2. I assume a 2.4 GHZ aircraft radio would be OK.
3. Are there any (hopefully free) plans or design links that would help me get started?
4. At what incidence to the main hull line should the motor be placed?
5. Any special considerations besides waterproofing the radio/battery compartment and its hatch?

That's all I'm smart enough to ask at this time.

Any guidance would be greatly appreciated.
Old 04-25-2016, 01:52 PM
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pinky_d_brain
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I did this up some time ago
Built up wing for design??
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Old 04-25-2016, 03:53 PM
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golf4two
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Thanks for the reply and diagram. But it seems that "dimension A" is not annotated, nor is "B". And what would the hull width be (looking from above). I'm still have no idea of what the approximate overall size should be.
Old 04-25-2016, 04:54 PM
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NEW222
 
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Look up 'Skimmer 400'. It will probably fit the bill for what you are looking for. I have just finished this build a little while back. It I a foam copy of the Dumas Lil' Swamp Buggy. AUW minus engine is about 13.5 oz. A 12" - 15" version would probably fit your bill.
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Old 04-25-2016, 05:13 PM
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golf4two
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Thank you kindly NEW222. between you post and PINKY_D_BRAIN's diagram I should be able to put something together. I'll look up the skimmer as well.

Thanks to you both.
Old 04-26-2016, 10:33 AM
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pinky_d_brain
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The A dimension is the Prop diameter. we start from there and work are way along. The B dimension is what you want it to be normal around 1". Width is about 1.5 x prop diameter. Angled sides help the boat slide in the terns without catching the water.
Old 04-26-2016, 04:09 PM
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golf4two
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PINKY, Thanks so much for the additional info. Should be easy to figure out dimensions now.
Old 04-27-2016, 07:18 AM
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pinky_d_brain
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Keep in mind this is a starting point not every boat works the same. It may have some strange performance problems when done but we can help you work them out. Its like a madden flight without the crash you have to work the bugs out of it.
Old 04-27-2016, 03:54 PM
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golf4two
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Thanks for the offer of help PINKY. Going thru my "stash" of available materials at the moment and "guestimating" target dimensions. Will let you know what I come up with.
Old 05-15-2016, 12:01 PM
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hi all i to am new to air boats i normally fly vintage helicopters
great advice thanks i will be posting pics of the build soon
Old 06-21-2016, 06:09 AM
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.Pinky, I'm sorry but as a total newbie I'm a little confused about the rudder annotation on your very helpful diagram. When you say that a higher rudder will flatten out a slide, do you mean a rudder of the same size but mounted higher up than shown on your diagram? And sorry if I sound retarded, but what exactly do you mean by "flatten out a slide?"

Also, if a shorter rudder will increase lean into a turn, and my starting point is a rudder mounted as in your diagram, do I get increased lean by taking material off the top or off the bottom to shorten it?

Your advice will be much appreciated.
Old 06-21-2016, 07:32 AM
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Originally Posted by pinky_d_brain View Post
I did this up some time ago
Built up wing for design??
i have just done a quick workout on your numbers as i am thinking of building a MK2 (to my Puddle jumper)
and i will be using an 11"prop on a 61 engine which would mean (if i have got i correct ) my next one would be 37"long x 17" wide and 1" hight
would this be correct

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