A build with a feminine touch?

foilmore · February 3, 2021, 10:13pm

Is it the original foil fish that came with that mast? I started foiling on that one 4 years ago. I weight just under 200 pounds, so it could be different for you. Below 12mph and it stalls. Above 20 mph it gets quite difficult to control. The speed that is most fun to me and easiest to control it is ~15-17mph.

3rd_ave_Lien · February 3, 2021, 10:48pm

This is really useful information. So, if I am lighter than you, in what direction will it affect the cruising speed?

By the way, how did you measure your speed? I want to have it built into my display.

I’m checking with the previous owner of the foil for the model. I haven’t used it much, I was keeping it as a spare. It has a very low aspect ratio.

My 13.5 mph cruising speed estimation is totally theoretical, I used my friend Dmitry’s java application with my actual wing shape and mast as a parameter, and assuming a total weight of 220 lb for rider and equipment.

foilmore · February 4, 2021, 12:01am

The best way to familiarize with different riding speeds on foils is using a boat with ski rope.

I have towed it behind a large (more than 20) and varied assortment of watercraft. At least 5 of them have GPS controlled speed to the .1 mph so I got pretty familiar with barking out a speed to the driver and adjusting it in very small and precise increments.

I believe that the more the wing is loaded, the faster it needs to fly. Your overall weight with electronics will be higher than mine with just bodyweight being towed on an unpowered board. If you post a pic of the wing, I can tell you if it is the same one. It most likely is.

3rd_ave_Lien · February 4, 2021, 12:13am

The previous owner also told me cruising speed was 17 mph.

foilmore · February 4, 2021, 4:43am

Yes, that is it. If you have not learned how to ride it yet, I can tell you after toughing it out behind boats and kites that adding a larger stabilizer with winglets and a vertical fin will really make it easier to ride and probably also help it fly at lower speeds. All of the LF wingsets have the same bolt pattern and will work with that fuselage.

3rd_ave_Lien · February 4, 2021, 5:44am

Actually, I’ve used it a few times. I found that I had to re-learn how to get started, but that otherwise it was pretty similar to my Cabrinha foil (also a beginner’s foil).

It’s just that I have no clue of what my speed is when I am out in the middle of the water…

3rd_ave_Lien · February 4, 2021, 5:12pm

Based on several inputs, my cruising speed is now

7.6 m/s (17 mph, 27.4 km/h)

which will require a good propeller if I want my motor to stay within reasonable limits for:

voltage (< 50V)
current (< 50A)

Is it achievable with a 3D printed prop ?
Or not even close? From my friend Dmitry’s (him again) marine prop calculator, I see that this is achievable with, for example, the expensive LiftFoil folding prop.

What is people’s experience with the performance of 3D printed props? I have printed a few props shared in this forum after adapting them for my splined motor shaft, but I don’t have a setup to test them yet.

I am also planning to use JavaProp and design a few props.

3rd_ave_Lien · February 4, 2021, 7:52pm

UPDATED Feb. 23, 2021

So here are my cruising requirements:

motor MTI65162 operating at around 3500 rpm
speed: 17 mph
thrust: 15 to 20 kg (theoretical 10 kg)
current: < 50A
volts: < 50V

Using Dmitry’s marine prop calculator, I gathered the following data for different props (D=diameter, P=pitch)

 PROPELLER        SPEED   Volts  RPM  Current (Power)  Dynamic thrust
1. Maytech 7.5X7 16   mph 30V   2700  50A (1450/1250W) 29 kg
2. Same but 6X6  17.4 mph 35.5V 3400  28A (990/860 W)  20 kg
3.          5X6  17   mph 34V   3200  15A (500 W)      12 kg
4.          5x5  17   mph 41V   4000  17A (700 W)      13.6 kg
5.          6x5  16.4 mph 40V   3850  36A (1500 W)     26 kg
6.      5.5x5.5  16.3 mph 36V   3500  20A (700/600 W)  15 kg

So with a 7" diameter, the RPM is kinda low, I get more thrust than needed and waste power. The current required is too large.
With 5" diameter, the thrust is on the low side, not much margin for error.

A 6x6 or 5x5 prop seems adequate. I’ll start with 6x6 to be on the safe side, and try 5.5x5.5 later if I can, to reduce power consumption.

This is Dmitry’s beautiful Xcel marine prop calculator I’m using:

JetboardCologne · February 4, 2021, 8:40pm

this is the LF Rocket Foil , not Happy Foil.

Happy Foil is smaler
i used it on a intflatble Mala Board with 6s .

greetings Frank

sat_be · February 4, 2021, 8:42pm

D=6" P=6" Seems a good choice, I would not go below 6” Pitch, especially with the 100KV motor. The Flying Rodeo Alu prop has the same diameter and pitch and it even works well with the 120KV motor.

JetboardCologne · February 5, 2021, 9:26am

Rocket

Happy Foil

foilmore · February 5, 2021, 2:40pm

How does the Happy foil compare to the rocket?

Valhalla · February 5, 2021, 3:53pm

I believe if you aren’t happy with either wing you can switch to the first gen cloud IX. I believe they used the liquid force mast to save costs before switching to their own in house carbon masts.

JetboardCologne · February 5, 2021, 4:17pm

Rocket and Happy only for light drivers…
Happy brought 3km/h more too lift, but he is faster 2 - 3kmh
Greetings Frank

foilmore · February 5, 2021, 5:22pm

Yes, I have the Impulse/Cloud IX wings too and am very happy with them. I was just curious since I had not tried the happy foil yet.

brycej · February 5, 2021, 5:56pm

Happy foil needs a ton of speed to get going but was slightly faster compared to slingshot speed skate and infinity 84mm. Happy foil is much more finicky as well, I wouldn’t want to learn to foil on it.

Fun to have different things to try though!