DIY twin motor mono build 'G-Force'

[Dirk Jan Cozy]

Here's the video of the entire process, from mold making to finished product:

 

[Dirk Jan Cozy]

I made good progress with the build. I installed both esc's, reinforced the lipo tray, made a servo mount and modified the hatch for the gps.




Here's video part 8:

 

[Mike Bontoft]

Very nice work! My last build with counter rotating props on a mono had too much lift at the rear. I will be very interested in how yours works.

 

[Dirk Jan Cozy]

Thank you Mike. I'm curious too, and if the boat does not perform as expected, I might try shorter stinger drives. I hope to find out soon

 

[Dirk Jan Cozy]

I finished the second stinger and got the motor wiring sorted. Soldering these motor wires was a pain. They are lacquered and need thorough cleaning before they can be soldered.
I hope to do the maiden run next weekend.

 

[Flemming Breil]

VERY cool. Congratulations on the patience!!

 

[Dirk Jan Cozy]

Thanks Flemming, patience is the key factor

Here's the next update. 2nd stinger is finally installed! Wiring and motor cooling is sorted as well.

The ponds are frozen here, but I hope to run it in the next few weeks

 

[Dirk Jan Cozy]

The G-Force had it's maiden run this weekend.
I ran 2x 2 lipo's and the boat handled pretty good. It has a little bounce and it spins out in tight corners, but I will work on that for the next run.
I got 62 ad 64mph on the runs. It's a good baseline, from where I will work on increasing the speed.
The Speed goal is 87.5mph (140km/h) so the tuning journey starts now.

 

[Dirk Jan Cozy]

I made some improvements on the G-Force.
I added a brace to the rudder arm, and I sharpened and balanced the propellers.




I can't wait to take her out again and set some speed numbers. Here's the video of the modifications:

 

[XtremeRcBoats]

Looks great again.
What I've seen with long rudder brackets is to add a horizontal brace for stiffening instead of vertical.
Do you feel it was going up and down?

 

[Dirk Jan Cozy]

You got a good point there.. I might add a side-brace too, as the rudder is actually more slim sideways.
I didn't notice any rudder movement. I added the brace to protect the rudder from breaking when I flip the boat.
I appreciate your input!

 

[Dirk Jan Cozy]

This weekend I ran the G-Force and I got some good results. I fine-tuned the stinger angle for the 43mm 1.6 golden props and I got a new speed record for this boat.

After that, I ran with the 44mm 1.9 pitch props. The G-Force runs very stable with these props. Maybe a bit too wet, so I will move the lipo's to the back of the boat a bit more, next run.

Here's the video:

 

[Dirk Jan Cozy]

I broke the rudder blade on a recent run of the G- Force. I made a new one, and took the boat out again. She ran pretty good, although this pond is too small too fully stretch the legs of this boat. I got 74mph with twin 3670 Rocket motors and 44mm 1.9 props. Basically a very budget setup.
Unfortunately, I had a nasty crash and I blew the hatch off. The boat sank halfway, but luckily no big damage. Just the hatch and the hatch mounting.

Video here:

 

[XtremeRcBoats]

Dirk-jan, too better protect the electronics you can also spray/soak them with CorrosionX. That is what I normally use.

 

[Dirk Jan Cozy]

Thanks for the advice Xtreme I will do that.
The issue is, the brass tube holding the flex shaft is well below the water line, if the boat lays still in the water. In the beginning, with a freshly greased flex shaft, water is kept out. But after some running, grease is pushed out of the teflon liner, by the thread of the flex shaft and I guess that's where the water starts to come into the boat.

I checked the water cooling systems, and it's leak free. The flex shaft / brass tube showed leaking water after a while in the bath tub.

 

[Peter Wibe Enevoldsen]

Thanks for the advice Xtreme I will do that.
The issue is, the brass tube holding the flex shaft is well below the water line, if the boat lays still in the water. In the beginning, with a freshly greased flex shaft, water is kept out. But after some running, grease is pushed out of the teflon liner, by the thread of the flex shaft and I guess that's where the water starts to come into the boat.

I checked the water cooling systems, and it's leak free. The flex shaft / brass tube showed leaking water after a while in the bath tub.

Sometimes the teflon does not fit perfectly and it leaks between it and the brass tube ive had that a few times and its fixed by just adding some tape to the outside of the teflon
I hope you find a good solution, leaks suck

 

[Dirk Jan Cozy]

Thanks for the advice. I will try that

 

[Dirk Jan Cozy]

Here's the video on making the hatch and the hatch mounting on the hull:

 

[Dirk Jan Cozy]

The G-Force got some paint. Just the 2k clear coat is left.

 

[Luis Oliveira]

The G-Force got some paint. Just the 2k clear coat is left.

View attachment 325111
View attachment 325112

Awesome paint scheme. Looks great!