mini Predator rigger I built for my son

[kwiktsi]

I just built this over the last couple of days for my 5 year old boy and got it out for a test run a little bit ago. I got the plans online, shrunk it down to about 17" and laser cut the pieces for it. My laser is smaller and will only cut up to about 11", so the longer sections were done as 2 pieces. It turned out much nicer than I had expected and is definitely a lot faster than I had planned, the 4200kv motor on 3S is a bit much for a 5 year old! I have a 2S I'm going to try next outing as well, see if we can get it a bit more age appropriate lol. I went with a straight prop shaft for simplicity and because resources are limited around here but at full throttle it want's to push the nose down and the rear starts hopping. I'm going to have to use a flex/wire drive and strut on it, which I'll round up the parts for. This was just a cheap quick toy to put together for him using spare parts and some hardware store brass but it seems to have a lot more potential than I had anticipated!

[kwiktsi]

couple more

[785boats]

Nicely done.
I hope your son appreciates the effort that the 'Old Man' has put in for him. Or did you do it more for you?
That motor is more a 2s motor than a 3s one anyway. 46000 revs is a bit high. Things will wear out fast.
Have the battery as far back as possible. Don't be afraid to add a bit of lead at the transom to keep the prop down. There are many straight shaft boats that work well with a bit of weight back there to counteract the angle of the shaft.
All the best.
Paul.

[Jeff Wohlt]

Yes, depending on his age it will be waay too fast for him. Go for a about 25,000 rpm. Yes, 46,000 is crazy rpm and drives and other items will not last long. Let me know your specs of the drive and I will get you one in the mail.

[kwiktsi]

Nicely done.
I hope your son appreciates the effort that the 'Old Man' has put in for him. Or did you do it more for you?
That motor is more a 2s motor than a 3s one anyway. 46000 revs is a bit high. Things will wear out fast.
Have the battery as far back as possible. Don't be afraid to add a bit of lead at the transom to keep the prop down. There are many straight shaft boats that work well with a bit of weight back there to counteract the angle of the shaft.
All the best.
Paul.

LOL, it was a little of both :). He wanted something faster than his Miss Geico 17" and I wanted to try laser cutting and scratch building something as I had never scratch built a boat before. The 3S with that motor was more for me though :D. I have a 2S pack I was planning on using for him, I just wanted to go right for the 3S to see if it would work knowing I can always go 2S if it did. You can't tell me you want "faster" and expect me not to over do it, it's just not my nature lmao. I also have another similar motor that is ~2400kv I was kicking around possibly trying on 3S as well. I was wondering if moving weight back would help, it gives me something to try.

Yes, depending on his age it will be waay too fast for him. Go for a about 25,000 rpm. Yes, 46,000 is crazy rpm and drives and other items will not last long. Let me know your specs of the drive and I will get you one in the mail.

I'll get the stuff measured up and over to you shortly. Thanks!



What would you guys say is a good weight for something this size? The boat weighs 9.6 oz without battery, 13.4 with a 1300 3S.

[kwiktsi]

Well, made him a display stand so he can keep the boat on his dresser.

edit- added a couple of better pics, the lighting sucked on the first one.

[785boats]

I've got no idea on what weight is best for that size.
But I do like the engraving on the stand.
It certainly looks good on display.

[NorCalZ71]

Got a pic of your laser? Home build or off the shelf? Looks like it cuts pretty smooth!. I have most of the parts for my laser build just no time...

Kevin.
Nsr customs.

[kwiktsi]

I've got no idea on what weight is best for that size.
But I do like the engraving on the stand.
It certainly looks good on display.

Thank you! He loves it too and looks good on his dresser for him :).

Got a pic of your laser? Home build or off the shelf? Looks like it cuts pretty smooth!. I have most of the parts for my laser build just no time...

Kevin.
Nsr customs.

I can take some. It is just the typical 40W chinese laser that is all over ebay and the like. It works pretty well but is starting to lose some power and is taking longer to cut the 1/8" birch than it used to. I know the lens is getting cloudy so I need to replace that, but I have a feeling the tube is getting weak too. The Moshidraw software sucks but is usable using Corel to design and such once you learn how to work around the faults. Tends to be glitchy at times though.

[NorCalZ71]

I'm working with mach3 at the moment trying to finish up a sherline 5400 Cnc conversion then ill use it to build the laser frame. I build all my drivers from kits or parts.

Kevin.
Nsr customs.

[kwiktsi]

That's the best way to go. The Moshi stuff is like a coloring book in comparison. Though, Corel makes it a LOT better since I can design stuff in corel or import my Autocad files and then export them to Moshi and cut. If I relied solely on the Moshi, I'd still be sitting there cutting circles or something lol.

[kwiktsi]

Well, figured I'd update this thread. I have since gone with a wire drive and made a strut for it. Performs MUCH better than it did with the straight shaft, though I feel the bend may be a bit too tight for the .062 wire and I should have gone flex with it. Not gonna bother right now though, maybe down the road I'll experiment with a flex. I also have to do something with the turn fin setup, too much flex in it and the sponson lifts out of the water and it rolls when I try to turn at speed.

Also, fun times with it the other day- flipped it over and had no radio control since it is 2.4. While waiting for the wind to blow it back, I decided to throw my pursuit in the water for a bit (same radio). After a few minutes of running the pursuit, I noticed the rigger was heading towards the tall grass, so I wanted to give it a little push with the pursuit to redirect it. Well, the push ended up rolling it back over and now I had two boats operating on the same radio with reversed steering on one. Took some serious concentration to get them both back to shore lol.

[Jdown26ty]

Quick question if I may. Everybody posts KV in their thread but what about motor case size? 28, 36, 40.... And how long do they need to be? I'm fed up with my nitro miss Budweiser stalling in the middle of the pond and have been collecting parts for FE. Where can I get size recommendations? 1/10 miss bud, converted to FE. 31" catamaran, and a predator rigger with a 23" tub. With 2s in the rigger and 4s in the others.

I know the knowledge is here but you keep it well hidden.

[NorCalZ71]

in a smaller hull like his rigger a 28mm can is suitable, in larger hulls like your 1/10th mrs bud a 3660 or 3674 would be suitable.. in larger hulls you would move up to 40mm etc...

[Jdown26ty]

in a smaller hull like his rigger a 28mm can is suitable, in larger hulls like your 1/10th mrs bud a 3660 or 3674 would be suitable.. in larger hulls you would move up to 40mm etc...

Thank you! In the 31" catamaran that I have, would a 3674 be acceptable or would that be considered larger hull and require a 40? I assume large diameter or length provides more torque. But wat is the cost? Higher amp draw?