Fly a boat exercise

Discussion in 'Boat Design' started by Saqa, Jun 3, 2021.

  1. BlueBell
    Joined: May 2017
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    Location: Victoria BC Canada

    BlueBell "Whatever..."

    Are you familiar with the Sea Sled design by Hickman?
     
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  2. mitchgrunes
    Joined: Jul 2020
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    Location: Maryland

    mitchgrunes Junior Member

    (BTW, given my failures to adequately control surf board, SUPs and windsurfers, I have not chosen to try hang gliders or kitesurfing. So much of this is speculative.)

    In general, I believe that most kites are actively stabilized by control lines under human control, rather than being inherently stable. Some degree of inherent stability may sometimes be a desirable feature in practical commercial and military craft, but much of the fun of human controlled craft comes because you have to stabilize them. (Think bicycles, motorcycles, wind surfers, downhill skiers, skaters, whitewater kayaks and canoes, tight rope and slack line walkers, etc. Even walking, for two footed beasties, is an exercise in active balance and stabilization techniques, using weight distribution, small time scale internal body part motions and internal tension pulls, etc., but we master that as kids, so it doesn't seem so hard.) However, the tail provides a degree of passive pitch and yaw axis stabilization.

    However, in front of a place on the Ocean City boardwalk that was (is?) called the "The Kite Store", I often saw kites that were attached to fixed points over the beach - taking advantage of a constant direction wind. (A great advertising technique.) (That was also the store where I first saw videos of kitesurfers.) I guess if you have enough control lines, that is possible, under the right conditions.

    Perhaps kitesurfers don't meet your full intent. Nonetheless, kitesurfers (see the Wikipedia description on kiteboarding), in which a human is flown in the air and/or pulled in the water, suspended by control lines, are often controlled using just 2 control lines between the human and the kite. That has me confused - in most aircraft, you do need to actively control all 3 attitude axis - roll, pitch and yaw. Since most kitesurfers don't have a tail, and the ones I have seen only have 2 control lines, I'm not clear how full three axis control over the kiteportion is established. In particular, there should be a degree of confusion between controlling pitch and yaw. (In contrast, for a hang glider, because the flyer is more firmly attached to the kite, the flyer's weight distribution and body configuration can establish some degree of pitch control, if I understand correctly.) I suppose the flow of the air across the width of the wing, (combined with the drag of the surfer in the water when they are in the water, and air resistance when the surfer is in the air), provides a small degree of passive pitch and yaw stabilization, but that intuitively seems pretty tenuous and indirect when they are in the air.

    Incidentally, athletic windsurfers do sometimes briefly jump or bounce off the the surface, and can sometimes somersault through the air. I do not know enough about them to know whether any have true hydrofoils, but many are certainly planing hulls, and under the right conditions (unlike my attempts which mostly rapidly ended with me in the water), can skim the surface at remarkably high speed, which is pretty close to flight. There too, active human control, using weight distribution, active tension pulls by the user, balanced against the wind, provide pitch and roll control. Hydrostatic interaction with the water, combined with the user's forward/back position provide yaw control.

    Fortunately, planing hull boats are not considered aircraft, and are not subject to FAA/FAC rules and control, even if they briefly leave the surface. :) (But to a significant extent kitesurfers and hangliders are.)
     
  3. Saqa
    Joined: Oct 2013
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    Location: Hervey Bay

    Saqa Senior Member

    I am. I read up all material I could find as well as everything on the TX18 and the sled madness thread. It left me with the impression that to work well it needs to be fairly large and heavy and very well powered to be stable and not skitish

    I do not know if the conclusions I drew on that is correct. It's just based on holding the entire 3D shape in my head and imagining the interactions with elements. Lol like a mental CAD running on intuition rather than algorithms. I know it sounds silly, but I am able to bring into physical being lots of complex items all from that 3D mental image

    One current project is a headless 4 string electric bass at sub short scale for outdoors practice. Outline hacked out with a twin cutter, then entire thing carved with scalpel and hand rasp from mental image. Timber is old spotted gum. Shape is a tribute to the impression of the body that I make sway with the bass lines and also one that I worship :) I used some off cut to carve the bass clef too
    [​IMG]TB004
    [​IMG]TB003
    [​IMG]TB002
    [​IMG]TB001

    I don't know the reasons why, but when I look at the undersides of my SW3500, it appears to be a twin sled structure optimised for higher weight to size ratio than other material boats in that size. My mind tells me that the sled and cathedral bottoms work well with some weight on it. Again when I see them, it just cries out that different exits needed for ultra-right built

    Mitch
    I observe kitesurfers a lot from Urangan pier in Hervey Bay. This was the inspiration for my original thread about kite driven WIG

    Over 35 to 25yrs ago I used to be really into hobby DIY kites. Absolutely zero interaction with any kite shops or resources. It was all about cellophane, paper, bamboo, reeds, balsa as materials. Cotton and spectra lines. Lol, even milo tins with a stick through it spools for the lines. You won’t believe how easy it is to deploy and pull in a kite with a milo tin :D

    Made the first one by copying a other kids newspaper affairs with coconut leaf frond spines and flour n water batter glues. My latest one was a two-metre job in 20012 that I designed to sit stable in 25-30knot constant winds at the point of the Ellington Peninsula in Fiji. Only one line (160lb spectra run from a butterfly jigging outfit wearing a conventional lever drag reel carrying 300m), that one line shared to two attachment points only on the kite. I could get stable altitude from around 3m of line out to max out. I could keep it in the air all day

    For straight line stability, only one axis needs to be under operator control. The control for other axis is built into the shape of pressure areas and their exits. This tells me that if ballast in the form of optimised COG was placed at where the single line splits and appropriate thrust employed, she would hold stable. Steering with vertical and horizontal flap additions controlled by boat push-pull control cables and simple attachment to a handlebar. I could be totally wrong about the ability to control direction like that from onboard, as I have never tried that. It can be easily model tested though

    I am of the mind to first come up with a few options that can get the job done than look up regulation requirements and chase the appropriate tickets and things if I decide to proceed

    Anyway, thanks for your input guys. It is much appreciated
     
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  4. dreamingbarrierreef
    Joined: Oct 2018
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    Location: Colorado

    dreamingbarrierreef dreamingbarreef

    Wow... I just want to say thanks for sharing pictures of the bass! That's one piece of a fine art there.
     
  5. mitchgrunes
    Joined: Jul 2020
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    mitchgrunes Junior Member

    Oh I get it now. The control bar combined with COG placement gives you active pitch and roll control. Passive yaw stability is provided by airflow over the wing.

    Airflow over the wing is insured by air or water resistance on the human. (Or if you use a motor/propeller in the water to pull you forward, by that.)

    In principle, you don't even need flaps.

    A beautiful and elegant concept!

    Do you think a glider pulled by a air or water propeller driven by a waterborne motor would be easier to build then a plane driven by an attached motor?

    (Hmm. Control could rapidly evaporate if the motor hit a submerged object and stopped. Or if the lines between the waterborne motor became tangled in the propeller. But nothing is perfect.)

    If all you want is a skimmer, a surfboard, driven by waves and gravity, is a lot simpler.

    Given the recent interest in UFOs, you could have fun and experiment with a flying saucer shaped wing, inflated by airflow, somewhat like a sail. :) Flaps could give you active yaw control, so you could have full 3 axis active attitude control.

    (Yes, I know the difference between UFOs and UAPs- among the many unidentified objects that form the majority of objects detected by almost any remote sensing system, due to lack of sufficient information or detail - and hypothetically identified extraterrestrial aircraft or spacecraft - which would have been classed as identified objects, not UFOs or UAPs, and would presumably not have been listed in the recent report to the U.S. Congress on UFOs and UAPs. It was Congress's prerogative to waste time, money, and credulity learning about the former.)
     
  6. Saqa
    Joined: Oct 2013
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    Saqa Senior Member

    Thank you for understanding the crazy thots that I am mulling

    Don't be surprised if the drawing take on the modern cylon raider or treky bird of prey shapes ;)

    Drawing something that does look it should be wearing disruptors atm
     
  7. dreamingbarrierreef
    Joined: Oct 2018
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    Location: Colorado

    dreamingbarrierreef dreamingbarreef

    Also, (if I may add some pesty (safety related again) details I hesitated to mention) with a drone pulled kite method, there could be a serious issue if you drop the remote or if the link to drone is somehow broken, then you lost control of the rig. So this may need a plan B. The easiest way perhaps if you cut the lines, the kite could land safely. But then, the drone still become uncontrolled, potentially lethal, torpedo. More elegant way you may need to integrate a kill switch. But a kill cord type solution probably not quite reliable considering the length. The way I see is a digital type with a watchdog timed circuit to an immobilizer. Very complicated. As to a DIY at least. And still not guaranteed to be reliable.

    Skimmer definitely lot simpler.

    Or the RIB glider that's already proved.
     

  8. Saqa
    Joined: Oct 2013
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    Location: Hervey Bay

    Saqa Senior Member

    Take a look at some thundercat vids on youtube. See how they skim in the surf? I believe that optimising COG and increasing air dam area will provide longer, more sustained skims. A thundercat split and attached to either side of my single pontoon might just do that

    I have a new inspiration to look further into a WIG
     
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