Go Back  RCU Forums > RC Boats > RC Airboats
Reload this Page >

9th RC airboat build - Selph Inflicted .40 series Tapered Flat Bottom

Notices
RC Airboats Discuss R/C Airboats here!

9th RC airboat build - Selph Inflicted .40 series Tapered Flat Bottom

Old 10-03-2015, 05:21 AM
  #1  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default 9th RC airboat build - Selph Inflicted .40 series Tapered Flat Bottom

This boat will be named "Jacob's Ladder" for my son. When he's old enough and if he wants it, it will be his boat.

This is the beginning of a new build. I am building an SI Tapered Flatty. I need a dry ground/dedicated air rudder boat and this should fit the bill. I have a whole pile of engines ranging from wimpy PeeWee Herman to big and beefy like Hulk Hogan on steroids. So it will be a fun boat to experiment with... Maybe 55mph on land??

I couldn't find 1/16" plywood any bigger than 1'X4' so I had to make my own. I took 1/8" Maple plywood pulled off an old door from my house and sanded it down with a floor sander to halve the thickness. It worked beautifully plus it'll have the character of old growth 75+ year old wood. I'll be marking out the other pieces over the weekend and hopefully get some pieces cut out.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	245
Size:	1.75 MB
ID:	2123317  

Last edited by 1QwkSport2.5r; 10-09-2015 at 11:10 AM.
Old 10-04-2015, 06:57 PM
  #2  
crispyspa
Senior Member
 
crispyspa's Avatar
 
Join Date: Nov 2004
Location: onalaska, WI
Posts: 1,791
Likes: 0
Received 0 Likes on 0 Posts
Default

This should be good.
Old 10-05-2015, 03:18 AM
  #3  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Now to decide if it needs to be a step hull or a regular flatty...

Oh yes, this will be good.
Old 10-05-2015, 05:32 PM
  #4  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

I'm taking the Tapered Flatty plans one step further (no pun intended?) and adding a step to the keel. This will greatly reduce the wetted surface when running on water and hopefully increase the speed potential. I'm going to cut the main runners out tomorrow and look at them to see if I want to do another stepped hull or not. I think I will, and if it totally sucks, chop it off and re-skin the bottom.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	197
Size:	1.20 MB
ID:	2123840   Click image for larger version

Name:	image.jpg
Views:	174
Size:	1.47 MB
ID:	2123841   Click image for larger version

Name:	image.jpg
Views:	162
Size:	1.45 MB
ID:	2123842  
Old 10-05-2015, 08:02 PM
  #5  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

I cannot find any information on step hulls and where the hell your supposed to have the step located? My last step hull flatty was a bit of a flop as I put the step in the middle of the hull. That boat seems to suck itself down and doesn't go nearly as fast in a straight line as it does in a turn. I don't want to have another flop like that... SO where the heck do I put the step?
Old 10-06-2015, 05:57 PM
  #6  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

I decided to scrap the step hull idea for now. I'm gonna build the boat according to the plan and add a step later on if I feel so inclined.

Main runners are rough cut - still need to cut the bulkhead slots, rake, and rudders. I have the bulkheads marked out and ready to cut. I'm using Liteply for the bulkheads which I'll reinforce with balsa and fiberglass at the seams. A few more pieces to cut and I can start assembling the hull.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	160
Size:	1.45 MB
ID:	2124114  
Old 10-06-2015, 07:56 PM
  #7  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Got a few more pieces cut out and test fit together.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	153
Size:	1.58 MB
ID:	2124171   Click image for larger version

Name:	image.jpg
Views:	149
Size:	1.39 MB
ID:	2124172  
Old 10-07-2015, 07:24 AM
  #8  
asmithnc
 
asmithnc's Avatar
 
Join Date: Feb 2004
Location: Lexington, NC
Posts: 919
Likes: 0
Received 0 Likes on 0 Posts
Default

I could have sent you my templates of the Cajun Gator flatty.
Whats the measurement between the uprights?
Old 10-07-2015, 08:18 AM
  #9  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Originally Posted by asmithnc View Post
I could have sent you my templates of the Cajun Gator flatty.
Whats the measurement between the uprights?
I wanted to build an SI Flatty. Paying homage in a way...

The distance between the uprights is 4.5". Overall hull length is 29.50" and widest part of the hull is like 17.50" or so.
Old 10-07-2015, 11:35 AM
  #10  
asmithnc
 
asmithnc's Avatar
 
Join Date: Feb 2004
Location: Lexington, NC
Posts: 919
Likes: 0
Received 0 Likes on 0 Posts
Default

Let me see what I have. If I have an aluminum engine stand that works I'll send it to you if wanted. What Engine size?
Old 10-07-2015, 01:59 PM
  #11  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Originally Posted by asmithnc View Post
Let me see what I have. If I have an aluminum engine stand that works I'll send it to you if wanted. What Engine size?
Sweet! It'll be a .46 sized engine of some sort. Thunder Tiger .46, Super Tigre .45 or Jett .56LX... The latter might make it go airborne, so I'm not sure about that yet.
Old 10-08-2015, 03:09 AM
  #12  
asmithnc
 
asmithnc's Avatar
 
Join Date: Feb 2004
Location: Lexington, NC
Posts: 919
Likes: 0
Received 0 Likes on 0 Posts
Default

It might take me a week or so to find out what I have...
Old 10-08-2015, 03:18 AM
  #13  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Originally Posted by asmithnc View Post
It might take me a week or so to find out what I have...
No worries Andy. Thanks for your help.


Tim
Old 10-08-2015, 08:36 PM
  #14  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Making a little more progress on the SI Flatty.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	152
Size:	1.67 MB
ID:	2124482   Click image for larger version

Name:	image.jpg
Views:	147
Size:	1.93 MB
ID:	2124483   Click image for larger version

Name:	image.jpg
Views:	122
Size:	1.62 MB
ID:	2124484   Click image for larger version

Name:	image.jpg
Views:	135
Size:	1.51 MB
ID:	2124485  
Old 10-09-2015, 12:33 PM
  #15  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Making more progress on the SI Tapered Flatty. I'm going to name this one "Jacob's Ladder" for my son.

Got the bow "nose" piece made. It's made of Ash. I also have the control cables plumbed and test fitted. I'll possibly start assembling the frame and bottom skin in the next day or so.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	146
Size:	1.15 MB
ID:	2124592   Click image for larger version

Name:	image.jpg
Views:	150
Size:	1.39 MB
ID:	2124593  
Old 10-10-2015, 11:53 PM
  #16  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

More stuff done on the SI Flatty. Added balsa triangle stock at all junctions on the keel and bulkheads for extra support. I have the top sheeting cut and fitted as well as the radio box supports.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	153
Size:	1.57 MB
ID:	2124843   Click image for larger version

Name:	image.jpg
Views:	142
Size:	1.72 MB
ID:	2124844   Click image for larger version

Name:	image.jpg
Views:	142
Size:	1.79 MB
ID:	2124845  
Old 10-12-2015, 07:52 AM
  #17  
asmithnc
 
asmithnc's Avatar
 
Join Date: Feb 2004
Location: Lexington, NC
Posts: 919
Likes: 0
Received 0 Likes on 0 Posts
Default

I do not have any extra pieces. Sorry! Great build so far!
Old 10-12-2015, 08:30 AM
  #18  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Thanks for looking and offering your help, Andy. Thanks for the compliments as well. This is a budget build - building it completely from stuff I already had on hand. Old plywood from a door, scrap flooring underlayment, and spare hardware. Trying to find hobby plywood wider than a foot is pretty tough and expensive, so using this stuff I have works well. The dimensions in the plans are a little funky - odd fractions of an inch - so I fudged some of them for ease of building. Overall, it's a nice design, easy to build, and it should be light and hopefully quite fast. The only pieces I have left to cut out is the side sheeting. Otherwise everything else is pretty much ready to go. If I'm lucky, it'll be RTR before the snow flies.
Old 10-24-2015, 03:35 PM
  #19  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

I finally got the side sheeting glued on. I should have made a jig to hold the sheeting in place instead of using masking tape; my sheeting moved a little bit after I taped it making a small gap between the side sheeting and the top sheeting. No big deal really, I'll just add a small piece of square wood stock of a different specie like I've done on other boats to accent it a little. As pictured, the hull is very light. Maybe 12-14oz so far.

edit: added balsa triangle stock around bulkheads and side sheeting. Added the radio box lid support also. Still a ways to go, but it's coming together nicely. As pictured with servos, hull weighs 2#11 3/4oz. I really really hope to come in less than 6# RTR minus fuel, but I'll have to wait and see. Beefing up the bulkheads and stuff for the top sheeting added some weight I'm sure. The engine and exhaust will be close to a pound, and I probably will have half a pound in the top sheeting, epoxy, and hardware. I'll have some fiberglass work to do yet too...
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	143
Size:	1.61 MB
ID:	2127386   Click image for larger version

Name:	image.jpg
Views:	147
Size:	1.88 MB
ID:	2127430  

Last edited by 1QwkSport2.5r; 10-24-2015 at 09:02 PM.
Old 10-25-2015, 01:03 PM
  #20  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Not much different than the last photos... Fiberglassed outer sheeting seams and coated most of the inside of the hull with thinned finishing resin. A few more loose ends to take care of and I'll glue the top sheeting down.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	160
Size:	1.84 MB
ID:	2127657  
Old 12-01-2015, 03:59 PM
  #21  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Progress has been slow due to health reasons. I have gotten the top skin sheeting glued on, engine mount assembled and fitted, and I put the first coat of dyed epoxy on the bottom keel of the boat. I didn't dye the epoxy real dark for the first coat since it'll need more than a couple thin coats to be well waterproofed. I'll dye one or two more coats and do a final coat of clear. All surfaces of the boat will be just clear epoxy except for the keel. The reason I'm dying the epoxy on the keel is because I had to make 1/16" plywood from 3/16" plywood and the top ply got a little thin allowing the glue that holds the separate plies together to show through the top veneer.

I'm still planning to use a .45 SuperTigre Diesel conversion engine on this boat which will either have a 3-blade 12x6 or 13x6 2-blade prop.
Attached Thumbnails Click image for larger version

Name:	image.jpeg
Views:	100
Size:	1.29 MB
ID:	2133429   Click image for larger version

Name:	image.jpeg
Views:	107
Size:	1.93 MB
ID:	2133430  

Last edited by 1QwkSport2.5r; 12-01-2015 at 04:03 PM.
Old 12-01-2015, 07:55 PM
  #22  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Second coat of dyed epoxy on the keel. I went a little heavier with the pigment this round just to get it done. I'll do one coat of clear over the top after a light sanding and thorough cleaning. My process to mix the epoxy is pretty easy - mix equal parts resin and hardener and thoroughly mix. Add pigment and mix thoroughly again. Add about 10-15% methanol to thin and mix. Brushing it on thin is important as epoxy has a bad tendency to fisheye, especially with additives in it.

It looks nicer than it would have with just clear on it given that dark brown glue showing through.
Attached Thumbnails Click image for larger version

Name:	image.jpeg
Views:	105
Size:	2.14 MB
ID:	2133499  
Old 12-01-2015, 09:01 PM
  #23  
crispyspa
Senior Member
 
crispyspa's Avatar
 
Join Date: Nov 2004
Location: onalaska, WI
Posts: 1,791
Likes: 0
Received 0 Likes on 0 Posts
Default

Hope you're doing OK. Nice job on the boat. coming right along.
Old 12-02-2015, 04:03 AM
  #24  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

I am doing okay. I get to wear a heart monitor for two weeks to rule out other issues.. As of now, the doctors say the issue I'm having is benign, but it could be a precursor to other things if the right circumstances happen at the same time. Not likely, but possible. I'm knocking on wood for now.

As as for the boat - all I really got left is getting the hull all coated up and re-installing rudders and linkages. I have some trim work to do on the outside edge, but that's the worst of it. Most of what's left is easy - I just need to find the time to do the work.
Old 12-04-2015, 06:59 PM
  #25  
1QwkSport2.5r
Thread Starter
 
1QwkSport2.5r's Avatar
 
Join Date: Oct 2006
Location: Cottage Grove, MN
Posts: 10,030
Received 27 Likes on 27 Posts
Default

Put a first coat of thinned finishing resin on the hull sides and radio box lid (not pictured). The dyed epoxy looks pretty good against the natural clear coated sides. The keel is Baltic birch and the sides and top skin is old antique carmelized birch plywood from an old door. I thought for a long time that it was maple, but the more I look at it, the more I see the birch in it. I love the color it gets when it ages. Anyway, here's a couple of pictures. I wanted to get two coats on the bottom before I trim the top and coat the top and engine stand.
Attached Thumbnails Click image for larger version

Name:	image.jpg
Views:	109
Size:	1.69 MB
ID:	2133973   Click image for larger version

Name:	image.jpg
Views:	101
Size:	1.48 MB
ID:	2133974  

Thread Tools
Search this Thread

Contact Us - Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service - Do Not Sell My Personal Information -

Copyright 2021 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.