Liberty's high speed RC OutRigger boat build thread

[Camaroboy383]

Have to love abc for that.. a casted back cut and a de-tounge right from the rip... That saves some serious work for sure ...

 

[LibertyMKiii]

ABC 1817 is a bit of a turd compared to the Dasbota prepared x645 prop. (wrong sort of prop for a mono hull)
Pulls around 2x the amps and the speed was lower. Rather disappointed. I may be able to improve the results by raising the stinger and a slower throttle pull, but in general, boats don't need a long run-up as cars do. Clearly the gims Ace 5000 mAh lipo really sucks. Check out that voltage sag LOL

 

[jkflow]

I wouldn't poopoo the lipo, you are pulling 450A

 

[LibertyMKiii]

I wouldn't poopoo the lipo, you are pulling 450A

Yeah that prop is really loading the amps bad.
Just comparing to my car speed run setups this lipo is the worst I have experienced and I have pulled 650+ amps on some lipos.

 

[Camaroboy383]

ABC 1817 is a bit of a turd compared to the Dasbota prepared x645 prop.
Pulls around 2x the amps and the speed was lower. Rather disappointed. I may be able to improve the results by raising the stinger and a slower throttle pull, but in general, boats don't need a long run-up as cars do. Clearly the gims Ace 5000 mAh lipo really sucks. Check out that voltage sag LOL

View attachment 244934

Is this prop cut on at all? Or just sharpened and balanced?.. There are several cuts you can make to relieve a lot of that load your seeing while still benefiting from the pitch..

You can obviously reduce the diameter, this will only get you so far in the unloading process.. I would refrain from anything over a 2mm total reduction..

You can also start to back cut the prop from the hub out onto the trailing edge, reducing the length of "spillway" will free up load.. you can start pulling that edge back as far as half the trailing edge..

Also as you said you can start to lift the strut to free up load, a certain amount of cavitation can really progress prop performance in certain situations...

Unfortunately it would take more than one prop to find what the combo likes.. still, this can completely be wasted effort and money if it never pans out.. But on the flip side, you could stumble across a prep that is above the rest... We would typically go through 6-8 props to find the proper prep for any particular setup..

Any way you go about it your plenty smart enough to make it happen man.. just keep at it..

 

[LibertyMKiii]

Is this prop cut on at all? Or just sharpened and balanced?.. There are several cuts you can make to relieve a lot of that load your seeing while still benefiting from the pitch..

You can obviously reduce the diameter, this will only get you so far in the unloading process.. I would refrain from anything over a 2mm total reduction..

You can also start to back cut the prop from the hub out onto the trailing edge, reducing the length of "spillway" will free up load.. you can start pulling that edge back as far as half the trailing edge..

Also as you said you can start to lift the strut to free up load, a certain amount of cavitation can really progress prop performance in certain situations...

Unfortunately it would take more than one prop to find what the combo likes.. still, this can completely be wasted effort and money if it never pans out.. But on the flip side, you could stumble across a prep that is above the rest... We would typically go through 6-8 props to find the proper prep for any particular setup..

Any way you go about it your plenty smart enough to make it happen man.. just keep at it..

I think this prop would probably perform great with a strut setup on a catamaran or rigger. This mono with a stinger is so limited....
I have a x645 prop that pulls under 200 amps at the same speeds so I am going to swap back to that one and try a higher kv motor on it.

In the end I was just shocked with how good the prop looked that it didn't go faster and a little frustrated with the 4hrs of working the prop and another hour at the pond for bad results. Hopefully, that time prepping the prop can be utilized when I setup this rigger noted in the thread.

My final goal for this ancient 80's mono is to get it up around 70 to 80 mph. I believe working with the x645 prop that is working really well with this hull is the best path forward versus spending hours at the pond trying to make this other prop work correctly.

 

[kspitters]

I think this prop would probably perform great with a strut setup on a catamaran or rigger. This mono with a stinger is so limited....
I have a x645 prop that pulls under 200 amps at the same speeds so I am going to swap back to that one and try a higher kv motor on it.

In the end I was just shocked with how good the prop looked that it didn't go faster and a little frustrated with the 4hrs of working the prop and another hour at the pond for bad results. Hopefully, that time prepping the prop can be utilized when I setup this rigger noted in the thread.

My final goal for this ancient 80's mono is to get it up around 70 to 80 mph. I believe working with the x645 prop that is working really well with this hull is the best path forward versus spending hours at the pond trying to make this other prop work correctly.

Any updates? I love the project and boats! I had a blackjack 24 a few years ago, but it only went 40.

 

[LibertyMKiii]

Any updates? I love the project and boats! I had a blackjack 24 a few years ago, but it only went 40.

Sadly I have not done anything with this one. I did some testing with the mono doing a gear drive to increase prop rpms by 25% to see how things perform. It loads up the amps quite a bit more. (one test was a 60% increase in amp draw but there was no consistent throttle application)

I also bought some flex drive parts for this one, but that's about it. Too many projects and work has picked up at least 2x.

 

[kspitters]

Thanks for the fast response! I’m quite new to the forum, but with Traxxas forum scarcely used, and formatted weirdly, i decided to try this. Loving reading your builds and knowledge!

 

[Tex Koder]

Thanks for the fast response! I’m quite new to the forum, but with Traxxas forum scarcely used, and formatted weirdly, i decided to try this. Loving reading your builds and knowledge!

Hey there,
Glad you found us and joined the group!

If you haven't taken the chance to introduce yourself.. Have a go here >
https://www.arrmaforum.com/forums/member-introduction/


If you have some more free time and enjoy reading about Cool stuffs and Fast rigs ,then check out >>

https://www.arrmaforum.com/threads/arrma-forum-3s-speed-run-challenge-2022.52860/ ;

https://www.arrmaforum.com/threads/project-aero-max-arrma-6s-based-speed-runner.56513/ ;

or

https://www.arrmaforum.com/threads/project-srx.55715/ ;

https://www.arrmaforum.com/threads/...-super-stretched-dual-motor-6s-goliath.57694/

 

[LibertyMKiii]

Thanks for the fast response! I’m quite new to the forum, but with Traxxas forum scarcely used, and formatted weirdly, i decided to try this. Loving reading your builds and knowledge!

Thanks man, this forum is a really special place unlike any other online.
Glad you are here!

 

[kspitters]

Sure is unique! I love it so far. I’ll go do the intro, I was hesitant because I don’t have an arrma. I don’t dislike them at all, but the lhs that’s 2 minutes from my work doesn’t carry arrma. The only one that does is a hike! Thank you for the warm welcome.

 

[LibertyMKiii]

A lot has happened in the past year and I decided to get back into boats over the past few months.
I had focused on a mono hull, which is now going 90 mph on 6s. Another boat I picked up is a JAE Zip kits FE33 outrigger, which has been 88 mph on 4s. This boat should go 120+ on 6s and just waiting on low wind to give that a try.

I am still learning, but one thing that is now abundantly clear is that weight is highly critical on boats. This 3d printed boat in past pages of this thread is rather heavy. I still have it and will look at how I could continue to work on it but love to tinker and build and decided to start a new project which is an ultra lite rigger.

New project - Ultra lite rigger

The idea here was to let things take shape organically and utilize what I have learned so far with RC boats.
For this project, I picked up a small 3630 TP motor having weight as priority #1. The XLX2 won't fit the bill either. The plan is to use the marine version of the MMX8s which is very lightweight yet still plenty of power.

I really enjoy building and sculpting from scratch and had always wanted to try my hand at hot wire cutting foam.
I'll admit it is hard to cut a clean straight line. What I found works best is to use clamps holding a ruler to the piece so you can run the wire across that straight edge. I also cut larger than I need and then sand the shape down to size. I am using traditional styrofoam which is ultra light, but is very sensitive when sanding. You have to apply very little pressure

At first I was playing with the idea of something very very very small. I bent a piece of aluminum to 13 degrees and cut a box down to the dimensions of the Castle Hydra X8s ESC.

After learning and talking to some knowledgeable RC boat guys my initial idea here was not good.
I left no room for the lipo batteries and was thinking maybe I could put them in the sponsons and route the wires through the boom tubes. Cool idea but not a good idea

This meant revising the shape to include room for the batteries in the main hull of the boat.
I picked up some BSI glue ideal for foam and was able to just glue additional pieces onto my existing shape.

There are plenty of wood made riggers out there and I didnt want to make mine square. I also wanted to retain the same idea of the trialing edge of the rigger being very slim and aerodynamic. 2 goals here is to make things rounded and add some contours which add strength. A large flat surface is flexible but curvatures add considerable strength with thin light materials. Given that light weight is the goal I will be having a thin composite layer on this boat.

At this stage you can see all the glued on additions and it looks much like a bullet train in some ways.

 

[LibertyMKiii]

By the way the sanding of this foam makes a giant mess and sticks to walls, you.... just everything!!! LOL

After further re-working the shape and smoothing.
In this picture I was looking at motor positions green in the back and black in the front.

If I go with a flex drive then the green rear position will work. If I go with a wire drive I would have to use the black motor position to reduce the shaft angle.

Sponsons are under construction also.

This one gives you an idea of how much shaping I do by sanding. A little more work is needed but overall the shape is looking great.

 

[jkflow]

What's your motor/prop combo on your JAE rigger?
I struggle to get above 55 with 2000kV on 4S, have a bunch of p-rops to be tried but advice is always welcome.

 

[LibertyMKiii]

What's your motor/prop combo on your JAE rigger?
I struggle to get above 55 with 2000kV on 4S, have a bunch of p-rops to be tried but advice is always welcome.

Well that setup was not ideal and should be slower. The knife blade rudder was barely touching the water and it pulled to the right pretty bad.
So far that rigger has only seen the ABC 1817 prop and loves it.

I am not sharing the KV because it might be a record-setting boat soon and I am listing it in a competition with prizes. https://gpsspeedrun.com/speedlist/2023

I will also say the LiPo makes a massive difference. With my mono hull I picked up 10 mph going from CNHL G+ to Onyx lipos (I was shocked!!!). Those RPMs are worth big MPH
The 4s run was the Onyx 8k Mccoy pack which is a monster. Based on the speed calculator on OSE's website you are right in the correct ball park. You just need more RPMs (higher voltage) to go faster.

 

[LibertyMKiii]

Doing a test tonight if different fabric weights and combinations over foam to see what works good and has enough strength.

The 6oz fabric does not like to confirm to tight curves. This has more to do with this specific fabric than being a 6oz fabric.

I'll have to keep that in mind on where I want to use it.

 

[LibertyMKiii]

I cannot perform a strength test just yet till it cures for 24 hours, but feeling the weight differences between them it is very clear the 6oz is heavy.
That tightly woven 6oz fabric does not wet out easily and needed more resin which is more weight. The 1.5 oz fabric clearly is the way to go and can wet out nicely with very little resin. I just hope it is strong enough!

 

[BIG TUNA]

I cannot perform a strength test just yet till it cures for 24 hours, but feeling the weight differences between them it is very clear the 6oz is heavy.
That tightly woven 6oz fabric does not wet out easily and needed more resin which is more weight. The 1.5 oz fabric clearly is the way to go and can wet out nicely with very little resin. I just hope it is strong enough!

View attachment 329383

What about using carbon fiber?

 

[Tex Koder]

@LibertyMKiii

I've got some 8mm CF rods if you need..
Just let me know long you need them cut.