As I said Jezza, the graph wuld have to be correct. Nothing else had to be “accurate”.
My original post was to Felix and you included yourself in the discussion which I am fine with but you are overlooking two major points:
- In canada we CANNOT have an open propeller and his post resonated for that reason…
- Safety with 2-4 hp motor has to be the SPORTS number one concern
While I admire your ingenuity and everyone else’s on the forum, water in a control box that turns one of these prototypes into a blender with a propeller set loose among swimmers will create lots of fresh new laws for the sport…NOT A GOOD OUTCOME
THe us military uses them so for them it is the best for a composite of reasons
low speed is precisely what we are interested in compared to speed boats…that was my piont exactly…thank you for making it for me
again thank you showing me where the disconect is…
By reducing propeller blade tip losses, the ducted fan is more efficient in producing thrust than a conventional propeller of similar diameter, especially at low speed and high static thrust level (airships, hovercraft). … Ducted fans offer enhanced safety on the ground.
fluid dynamics is fluid dynamics. i Know at high speed it is the opposite but i dont consider 20 km/h high spped…
The additional shrouding adds drag, however, and Kort nozzles lose their advantage over propellers at about ten knots (18.5 km/h). (LUCKY GUESS BUT OUT BY 1.5 KM?HOUR not bad for a retired guy
I NEVER ONCE SAID HIGH SPPEDD>>>we are interested in more than a 25 minute ride
and lastly, a durajet configuration with the much larger impeller at half the speed of a normal jet ski because I dont believe they use gear reduction and I doubt durajets pull out the lower end gears and replace them for 1:1 gearing…so I strongly suspect my application of a durajet design will comply with the canadian ana american laws and once a few ppl with your design philosophty donate parts of their bodies to science, it will be a universal almost darwinian type of law because honestly open propellers for foiling seems like the ultimate high risk design compromise…but I digress…
so a much larger impeller than a jetski, at a slower RPM will make this far more efficient than the super tiny super high speed jet drives like the lyft or efoil…would an open torqueedo ultra high efficiency propeller be better yes of course…put that on your boat NOT UR EFOIL!!! unless you like meeting nurses at the ER…
anyway Jezza you do you, my goal is the sport be safer
If you think 10% efficiency is worth people being maimed then I cannot convince you something LIKE the durajet is an option and would not require royalties as it is experied IP
And if you want to as efficient as possible for the last (extra) 5 km;hour t at the cost of people being maimed keep up the good work!