DiY twin mono 'Cozy G-Force'

[Cozy RC]

Thanks Jerome, for your input 👍.

This hull is based on the Wildthing, but it has quite many design changes. To reduce lift, I narrowed the hull. Also, the deck has angled sides to reduce frontal area. The V-angle of the hull bottom is also bigger towards the bow, to further reduce lift.

I will try a bit heavier lipo's, as well as shifting the weight forward with the original lipo's. 

Hopefully I can run the boat this weekend again 👍

[Cozy RC]

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

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

 

 

[Cozy RC]

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:

 

[brushman]

Hello,

nice improvement with the sharpening of the propellers! I think the red propellers have too much of a diameter, the 42/1.9 might fit better. Maybe enough to go to 125? Changing kV is the way to go, but it means reducing the diameter of the propellers because these Surpass motors don't have a high power density. HET RC 650-68/ 2250 would be more suitable...

[Cozy RC]

Hi Brushman, Thank you for your inputs. I agree with your advices. The motor rpm is noticeable lower with the 44mm 1.9 props.

I do have 42mm 1.9 pitch props as well. With a higher rpm motor upgrade I will consider 1.4 pitch props 👍

I think I can get 120km/h with the current setup. Sharpening the red props, a hair of uptrim on the stingers and I will also try a single 6S big lipo with parallel connector, to see how that will perform. 

[brushman]

yes,

your boat will be faster with the actual motors and 42mm red props sharpened, I think....

I agree for Higher Kv and 1,4 P/D ratio

As you will try a single bigger battery, high C rate, a bigger connector should be needed, XT 150, QS8, AS 150

[Cozy RC]

Last weekend I ran the G-Force in a small pond and I got a new speed record at 118km/h, running the 44mm 1.9 pitch props. 

I also tried a single 6S CNHL 5200mAh 90C lipo, but unfortunately, I made a bad crash and the boat sank halfway, because the hatch blew off. Here's a video of that run:

https://youtu.be/ELAW_-Yigs0

I didn't find the hatch, so I'm making a new one. I will make 2, one with a cockpit and one just flat. I like the looks of a cockpit better! But for speed runs, I will use a flat hatch.

 

[Cozy RC]

The hatch is carbon laminated, with a glass fibre section for the gps signal.

The hatch is secured with 4x M4 thumb screws. Next is the paint job 😎

[jerome lefebvre]

Hi Cozy 

Nice carbone cowl. 👏👏 quite some nice job 👍

By looking out your cowl works 
I been Wondering about top Speed with it  !! 
We know for fact ! With your flat decking the top speed being 118 kmh  ( great shoot )😁👏

It will be knowledgeable to see your top speed with your carbone cowl  !! 👍🙏 also  ( if ) you can feel any change’s about handling behavior with the cowl  design 👍

Regards Jerome 🙏

[Cozy RC]

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

https://youtu.be/bxpKazYAnYg

[Cozy RC]

On 3/3/2024 at 5:32 PM, jerome lefebvre said:

Hi Cozy 

Nice carbone cowl. 👏👏 quite some nice job 👍

By looking out your cowl works 
I been Wondering about top Speed with it  !! 
We know for fact ! With your flat decking the top speed being 118 kmh  ( great shoot )😁👏

It will be knowledgeable to see your top speed with your carbone cowl  !! 👍🙏 also  ( if ) you can feel any change’s about handling behavior with the cowl  design 👍

Regards Jerome 🙏

Hi Jérome,

I'm curious about that too. So far, I ran the G-Force once with cockpit. Not in great conditions, but I got 108km/h. 

I couldn't notice a difference with the cockpit hatch. Maybe if I run with- and without cockpit back to back. I will try that!

[Cozy RC]

I nearly finished the paint. Only the clear coat is left!

Same color scheme as my T800 F1 Tunnel 😎

[brushman]

Hello,

MERCUR-E would have been more suitable but that's my humor, the decoration is simple and looks good to me! what are the next engine/propeller combinations?

[jerome lefebvre]

Il y a 18 heures, Cozy RC a dit :

I nearly finished the paint. Only the clear coat is left!

Same color scheme as my T800 F1 Tunnel 😎

Hi Cozy 

I love your design work. 
it’s nice and sharp looking boat ✔️

Congratulations 👏👏👏 

Also !!! Thanks for the math 🧮 

It helps to understand few things about aerodynamic 😁

 

@ brushman. 
What a way to go. Mercur E 😂😂 well thought 👏👏👏

Cdt Jérôme 

[Cozy RC]

16 hours ago, brushman said:

Hello,

MERCUR-E would have been more suitable but that's my humor, the decoration is simple and looks good to me! what are the next engine/propeller combinations?

That's a good one 😄👍. Did you know Mercury is actually working on electric outboards? 😉

I will continue testing the current setup a bit more. 

I did order 2x6S 4000mAh 70C lipo's. The boat will be 225gr heavier, but I think the voltage of these lipo's will drop less than the 6S 3000mAh 100C lipo's. I hope for 120+ km/h.

The next step is 2x SSS 3674 2075kV motors. About 12% more rpm compared to the Rocket 3670 1850kV motors. Probably more torque as well. I think the sound of these high rpm motors will be awesome!

I also got some 42mm 1.9 pitch props to test. Maybe later I will buy a set of 3 blade props... 

Lots of plans with this boat. I keep you updated!

@Jérôme: merci 😎

[brushman]

Hello,

yes , give a try with the 42mm prop, 3 blades props are generally slower but...

Good point for the  2x3S 4000 70C, but for speed run 2x3S 3000 G+ are as good and lighter.

Which brand was it for the 6s 3000? 

[Cozy RC]

Thanks for the advice. Let's see about the speed! Both are CNHL lipo's.

[Cozy RC]

Here's the video on how I painted the hull:

https://youtu.be/WJfL3HNCsO0