Need your thoughts- Hobie Trifoiler/Dared Kiteboat/Self Design Frankenstien

Discussion in 'Boat Design' started by LeeDesign, Jul 11, 2018.

  1. LeeDesign
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    LeeDesign Junior Member

    I think its about right. Maybe. The center of effort, which translates to the pilots rear end in the seat since hes hooked up to the kite, should be located just behind the center of lateral drag, which is just behind the front foils. Right?
    So this kind of limits where you can move the CG. I would almost like to move the seat back a bit more, but since the cross arm utilizes the space beneath the pilots knees the arm would need to go backwards too; I don't really want to move the front foils back, as I'm trying to keep them in line with the cross arm to minimize torsional strain on the beam. This leave me with a kind of goofy looking central hull. Nothing to be done about it I guess?
     
  2. Doug Lord
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    Doug Lord Flight Ready

    The location of the CG* ,relative to the foils, on a foiler is absolutely critical. Nothing else matters as much.
    * kite load and CG=space place.
     
  3. LeeDesign
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    LeeDesign Junior Member

    More information please. Im not quite picking up what your putting down :)
     
  4. Doug Lord
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    Doug Lord Flight Ready

    See post #2 again. The line from the kite should fairly closely intersect the position of the center of gravity.
     
  5. MurphyLaw
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    MurphyLaw Senior Member

    Yes, I was wondering how the venturi effect would effect it, if I remember from physics the hole must be small in relation to the surface, I was thinking about doing away with the foam ball and just measuring the pressure at the bottom of the foil using the same hole. The 9axis sensor I have can measure speed and acceleration very accurately so I presume any venturi effect can be removed from the equation if you know the speed.

    I have the 9axis sensor and SBC already and a swimming pool, that ultrasonic sensor is crazy expensive, a non waterproof version only cost $3
    HC-SR04 Ultrasonic Sensor Distance Measuring Module https://www.pishop.co.za/store/sensors/hc-sr04-ultrasonic-sensor-distance-measuring-module
    I think I might order this one for $3 and pot it in epoxy, I already made a infusion leak detector using ultrasound so I think I will look at that.
    I think the best version for height sensor will be to use like autonomous cars use more than one sensor. Light and sound together or light,sound and pressure.
     
  6. MurphyLaw
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    MurphyLaw Senior Member

    Awesome! do you have the 3D file....

    What 3D package are you using I have 3DS max, I also have ANSYS 17 for the CFD

    I want to allow the hulls to point into the wind like the Sail Rocket, I think that is one of the reasons they were able to break the 40kts limit
     
  7. MurphyLaw
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    MurphyLaw Senior Member

    Here is an infrared distance measuring module for the Pi computer it can measure upto 80cm which should be enough. This is only $2

    Infrared Obstacle Avoidance Sensor https://www.pishop.co.za/store/sensors/infrared-obstacle-avoidance-sensor

    Here is an Ultrasonic distance measurer accurate to within 3mm. Will pot it in epoxy resin to make it waterproof along with the infrared one. This is only $3

    HC-SR04 Ultrasonic Sensor Distance Measuring Module https://www.pishop.co.za/store/sensors/hc-sr04-ultrasonic-sensor-distance-measuring-module

    Just finshed my concept hull design, will have 2 solid wing sails only 3m high. Cockpit is located level with the top of the mast can lower and raise the cockpit, cockpit has 2 ground effect wings to generate lift. Want to break the round the world record, the sail rocket could do 60kts in flat conditions, if I can take the same technology and get 40kts in rough conditions then it's in the bag. Doable, by keeping everything high, nothing apart from the floats and foils below 3m, the top of the masts will rotate 360degrees so if it capsizes then you can just rotate the wings to right again. Going to refine this over the week then take it into ANSYS and do CFD on it next week.
     

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    Last edited: Jul 22, 2018
  8. LeeDesign
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    LeeDesign Junior Member

    Hey Murphy, had a busy week so just now saw your posts. Im using Solidworks atm, prefer it over Inventor these days by a mile. How is your testing going? An electronic route would be very cool, if it could be worked out. Just a simple distance from water measurement taken from ahead of each foil, used to control angle of attack for said foils.

    Especially cool, and something ive been having a hard time incorporating into a mechanical linkage, is a way to allow the hulls to abruptly 'pop' up. Imagine a low wind condition day, and your trying to get up on your foils. With mechanical linkages the foils would be adjusted to max angle of attack, causing alot of drag, right? But with an electronic approach you could have an override setting, allowing you to set AoA to zero, get some hull speed up, and abruptly activate the system, popping up on the foils. This would be simple to do with electronics I imagine.

    Those range finder units you posted seem ideal to test with, especially at that crazy high price. The only issue i might forsee with them is the spray issue. But perhaps you could take several range readings over a period of, say 100 ms, and average them, then use that measurement to set AoA? I cant imagine a spray droplet being within the 'beam' too much longer than that, but perhaps my imagination is wrong. If so, perhaps you could mount two units side by side, say 5 inches apart, and average the readings between the two over a period of time.....

    Anyways, if your software is compatible with solidworks assembly/parts files, i could put it up on grabcad or something.
     
  9. MurphyLaw
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    MurphyLaw Senior Member

    I worked on a project for underwater headphones so I know the manufacturer in China who makes the waterproof stuff. It will be no problem to waterproof the sensors, high frequency sound does not need a lot of movement to make it so you can coat the diaphragms in tough coatings.

    I am going to get 3 different sensors, Infra-red, Laser and Ultrasound. I will mount above my swimming pool and then get a paint mixer to splash the water around and see which position, height,location etc. works best. Hoping to get the sensors next week.

    I am working on the CFD in ANSYS for the foil controls, you can use the simulation to see what electronic control to use, you could use it to find the ideal solution of pitch to apply for getting up on the foils as speed is increasing. Here is my very first foil CFD that I produced from my own foil shape.
    This is showing the pressure of the water around the foil. Hoping to use this to produce my entire boat. Give me a few weeks and I should have the hull shapes designed and tested. I might go for a scale Radio Controlled model first, I have a swimming pool and there is also a RC Lake just a few km down the road. I want to use wing sails and it's one thing making a full size test foil and another thing entirely making a test wing. I want to test the sailing ability before I commit to making full size 4m high wing sails. If you have a drop box or I can use my google one then we can share info
     

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  10. MurphyLaw
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    MurphyLaw Senior Member

    Just found this, so looks like ultrasound is the best way to measure distance to water. Hope to order the sensors tomorrow, should get here by Friday, I've also ordered a 25kg strain gauge to I can test the foils in the swimming pool, put them on a motor going in circles and attach the strain gauge to the top and can accurately measure how much lift they are producing you could get away without using a distance to the surface measurer if you could accurately measure the lift because long before the boat starts to rise or sink the strain gauge will pick up the change in lift from the foil, actually probably a better way of controlling the foils because you can adjust the pitch directly from the lift it is producing and not long after the fact in the boat changing height.

    If you got a second strain gauge( they are only $10) an mounted it in the direction of the boat, then you could also measure drag, you can quickly work out the drag and lift of the foil in real-time and adjust the pitch, this would work very well because it would always get you up foiling in the quickest time independent of the load on the boat. It would be the easiest to program for the best performance and reliability.

    How to Make a Water-Level Indicator With Arduino | Arduino https://maker.pro/arduino/projects/ultrasonic-arduino-water-level-indicator

    Here's the 25kg load sensor, they work in one direction only, you stack 2 above the foil, one pointing in the y direction for lift and the other in the x direction for drag. Need to find a 500kg model for full size boat, but 25kg is fine for a swimming pool scale foil and I don't want to spend the $100 for the larger ones if the idea does not work.
    [/URL]
    HX711 Module 20kg Aluminum Alloy Scale Weighing Sensor Load Cell https://www.pishop.co.za/store/sensors/hx711-module-20kg-aluminum-alloy-scale-weighing-sensor-load-cell


    Here's a waterproof anti jamming proof ultrasonic distance measuring device for only $25.

    DC 5V Waterproof Ultrasonic Module Distance Measuring Transducer Sensor https://www.pishop.co.za/store/sensors/dc-5v-waterproof-ultrasonic-module-distance-measuring-transducer-sensor
     
    Last edited: Jul 30, 2018
  11. LeeDesign
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    LeeDesign Junior Member

    Sounds like youve got a party going :) Let me know how the tests go, im quite interested.
     
  12. MurphyLaw
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    MurphyLaw Senior Member

    I just tested the ultrasonic detector with water and it worked fine and wasn't put off with splashing, it codes the signal it pings so it is not fooled by any other source of ultrasound, it doesn't just look for a return signal it looks for a return with the same code as was sent.
     
  13. LeeDesign
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    LeeDesign Junior Member

    How thick was the spray that you put up between the detector and the waters surface? This could be really cool if it works out. Sorry on my delayed response, life has been busy lately
     

  14. MurphyLaw
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    MurphyLaw Senior Member

    I'm not sure about the ultrasonic detector, it seems to be sluggish in it's response and would not be quick enough. I might take it apart and re-engineer it, I think the principle is sound of encoding the ultrasound and only reacting to ultrasound that returns with the correct encoding BUT I left it running for 6 hours connected to a servo and it fired off twice in response to sounds like door's slamming etc. I have since found a laser detector which seems awesome in comparison but have yet to run any proper tests.
    I am going to now test both the ultrasonic and laser detector together, I am writing the project up at this link.
    Open Source Boat Controller Project https://www.boatdesign.net/threads/open-source-boat-controller-project.60821/page-3

    Here it is together with the laser detector which is not much bigger than the cable it is attached too.
    MK1.jpg
     
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