whittling the wildthing - RC Groups
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Nov 07, 2010, 04:45 PM
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flying scrap's Avatar
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whittling the wildthing

hi guys i am building a 26" wildthing,i have built most of it and have
a 18 car engine to fit in it and a 40mm prop
my problem is how or what way to join them,a straight prop shaft
out the back or underneath ?
or a flexi shaft ? and what is the difference between a stinger
and a strut?
and does the prop shaft need to be level with the hull or would it
be ok having the prop point down abit
if you have any photos of the prop a setup i would be intrested
as for the prop setup
keep it cheap i am quite skint at the moment
thanks pete
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Nov 07, 2010, 08:10 PM
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coriolan's Avatar
This is from the electric forum but it also apply to IC boating for the difference between strut and stinger:https://www.rcgroups.com/forums/show....php?t=1321255
The Wildthing is a great boat in any size and do require a surface piercing set-up to run propely with a cable drive. 40mm might be a bit big for an .18 but being in the UK you can get all you need from Astec:
or if you don't mind importing:
Here is a picture of a typical Mono set-up similar to the Widthing, and Ron Olson's wild thing!
Last edited by coriolan; Nov 07, 2010 at 08:23 PM.
Nov 07, 2010, 08:40 PM
Registered User
siberianhusky's Avatar
This is the stern of mine, All home made hardware except the chinese rudder.
The finished length of the stinger is 2 1/8" from the transom.
.15 aircooled, 25" long.
Have not gotten it figured out yet, first day I ran it it snowed! Hasn't been a second yet.
So far I'v run a 1438, a seriously cut down 1440 and I think it was a x437/3.
With some tuning and perfect water I think the cut down 40mm prop could be fast if the hull is loosened right up. I think for all around reliable easy running the 38 maybe de-tongued to unload the prop a bit might be a better option. The little engines love rpm, unless you can get it screaming it won't have any power. There is almost no low end to them.
Flex cable and surface drive is the only way to go, keep the turn fin short enough so it is about out of the water with the boat going straight. Mine is a little long still.
Trim tabs are 1 degree positive on each side as of now. That will change as I get it up to speed.
I have a little positive angle on the stinger as well, about 1 degree as well.
I use a digital level to do set ups, if you keep notes it makes it really easy quickly set up your boat for different water conditions, or to get back to a good good setup after you try a change that doesn't work.
Hope this helps
Nov 08, 2010, 04:10 PM
Registered User
flying scrap's Avatar
thanks guys, i have ordered a stinger and a coupling
that cost a bit more than i expected, a normal propshaft is only
8 these bendy ones are dear
next i think is the rest of the bing hanging off the back i
will have to make these bits
does the rudder need to be short of the prop, as in between
the stern an prop ?
Nov 09, 2010, 08:46 AM
Registered User
siberianhusky's Avatar
Currently the back edge of the rudder is in line with the drive dog. Just where it worked out with the stock chinese rudder bracket. Running will tell if it needs to be changed,
All of that stuff was made with a hacksaw, dremel and drillpress, files, sandpaper and a 4-40 tap.
Even made the bushing in the strut, 7/32 brass tube with a flare on one end with a flaring tool, a few cuts made with a dremel to hold some lube, Garage at the end of my road let me use their flaring tool.
The chinese rudder works, about all I can say about it, up and down as well as side to side play, will be drilling it out for a bigger tighter rudder pivot and fitting a nylon washer to take up the vertical play. Cheap set screws that rounded out while I was trying to tighten everything up for the first time.
For the time it will take me to fix the problems I should have bought a name brand one. Only a few $ more.
At the same time I got a cheap hyperformance flex cable I didn't use, needs work as well, a big lump of brazing left on one side, needs to be ground down to round.
First time I tried a non Hughey cable and ended up buying one anyway. Not worth saving 4$ on!
this is the first boat I've used chinese hardware anywhere on and am not impressed with the quality control. Looks great in the pictures but not too good once it's in your hands.
Just measured the play in the rudder, at the bottom I get over 1/8" side to side play. Not acceptable!
Cheers, get her done and on the water! Have to live boating through people living father south for the next 5 or 6 months!
Nov 11, 2010, 01:26 AM
RC boat Rock Star
Here's some better shots of mine. I kept it simple and it ended up by running very well!
Nov 11, 2010, 06:47 AM
Registered User
siberianhusky's Avatar
Currently my tabs are all the way up, I'm going to try a run this weekend without them see how it works, If I don't ned them I'll remove them.
Nov 11, 2010, 09:41 AM
RC boat Rock Star
Note that there aren't any trim tabs on mine. I started off with using some but after finding out that it didn't need them they got tossed. I have a tiny turn fin also and wonder if that's really needed. Getting the CG right I feel is very important though for not using them plus a very flat bottom.
SH, I'd rotate the tuned pipe 180* as that will help from having oil build up in the pipe.
Nov 11, 2010, 11:18 AM
Registered User
flying scrap's Avatar
hi ron,thanks for the photos they are a great help,guess what
the post man turn up with today
a set of trim tabs and a stinger drive set no instructions an
no idea how it goes together,how far should the brass tube go
into the alloy bit ?and how close should the brass tube be to the
coupling and how an were do i bend it
as for the boat itself there is no mention on the plans as to what
goes on the bottom of the hull like spray rails? and something else
i can't remember the name of anyway
here is some photos
Nov 11, 2010, 11:31 AM
RC boat Rock Star
Good question. With some, the stuffing tube only goes as far as the transom where some others will either go maybe 1/8" or so outside of the transom but then some go all the way through the strut (i.e., Super-Vee 27's). For that one my best guess is to end it at the transom.
You can use the trim tabs for now and if you find out later that it doesn't need them, take them off. Look at my shots and you'll see that I did remove mine but left the screws in place.
If you built the stringer rails with a 3" gap use an Octura 3-30 mount.
Nov 11, 2010, 11:50 AM
Registered User
flying scrap's Avatar
If you built the stringer rails with a 3" gap use an Octura 3-30 mount.

i think mine are about 2 3/4" ,the brass does push in to the alloy a
bit maybe a 1/4" without much force
Nov 11, 2010, 12:14 PM
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wparsons's Avatar
Where can I find the plans for the wild thing in this size?
Nov 11, 2010, 01:22 PM
Registered User
coriolan's Avatar
Originally Posted by wparsons
Where can I find the plans for the wild thing in this size?
There is a plan in here for a 48" version (for gasoline engine)which is very similar to the original "Wildthing":
There was a thread a few years ago on this forum about a smaller version(maybe in the electric forum!). I still have the original article from the 90's for the A-class Wildthing and will scan it latter on. The plan from modelpowerboat can be scaled easily. This was the old thread for the electric wildthing, most apply to IC version:
Last edited by coriolan; Nov 11, 2010 at 01:44 PM. Reason: Add link to old thread
Nov 11, 2010, 01:57 PM
Registered User
siberianhusky's Avatar
Here ya go WP.
I would turn it but the pressure nipple causes issues! Blows out pretty clean if I stand it on its tail and blip the throttle a couple of times, Gets taken off and drained after a days running.
Want to ditch that pipe anyway, really heavy! it's like 1/16" aluminum!
Nov 17, 2010, 11:21 AM
Registered User
flying scrap's Avatar
hi guys, been doing a bit more ,i took a wild stab in the dark
and fitted the stinger it seem about right,i picked up some
turn fins on ebay, and made a rudder maybe a bit short but
i will try it before making another
need to find a prop, what size would be a good starting point
for an .18 motor

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