New High Performance Monofoilers

Discussion in 'Sailboats' started by Doug Lord, Dec 19, 2008.

  1. Chris Ostlind

    Chris Ostlind Previous Member


    You don't see any serious discrepancy in the bold faced statement?

    When something requires MUCH practice to get under control, that very process does not, typically, allow one to make definitive predictions as to "it will be slightly faster".

    There must be a hundred different variables in the mix, the biggest being the sailor's eye-hand motor skills, coupled with an inherent potential savvy. Maybe you've never functioned at that level of sporting skill before, but there's no guarantee of anything simply because you slap on the flavor of the day, go-fast setup.

    You build it, you prove it by kicking the crap out of everybody out there with that "slighty faster" potential after all the many hours of practice... and someone will sit up and take note. Breathing heavy in the microphone does not make for a done deal.

    Sounds like you better get out to that shed, or Bill B is gonna get on the water with the gadget long before you do.
     
  2. Doug Lord

    Doug Lord Guest

    High Performance Monofoiler Design

    I've already sailed a manual system on my first foiler and on three rc test boats-it is doable and will allow the kind of crash free control that will allow a bi-foiler to fly higher as Beaver suggests. Others have also experimented with manual control including David Lugg/Alan Smith the R class guys and a Swiss Moth sailor(just recently). Not only is it potentially a faster way to sail a bi-foiler but it is a lot of fun-full size or rc.


     

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  3. Chris Ostlind

    Chris Ostlind Previous Member

    You've cut and pasted your own post from one hour ago? This does what?... make the things you wrote somehow more magically correct?

    I wish I could do that and make it stick in my work. I could retire yesterday, simply because I said it enough times.

    Sheesh.

    Shall we call in the Moth foiler crew from SA to put down this vapid claim of manual control, once again. You rode around on that bag of bones idea over there and got your fanny whupped but thoroughly by the guys who actually do sail and design twin foilers. What is it, Doug.... a slow news day for you and now you are reaching back for a six month old doughnut to tide you over?

    Tired claims and oblique references do not make for a substantive argument.
     
  4. Doug Lord

    Doug Lord Guest

    ===============
    How can you call manual control a "vapid claim" when you've never done it on model or full size? Very,very few foilers have but that will change because the quest for speed in development classes like the Moth will go after that last nth degree of speed. And, people who have NEVER SAILED A FOILER with manual control don't make particularly good advocates for the "aw hell it will never work" point of view.
    I have foiled with manual control on both rc test boats on my 8 year old 16 footer-I know it works and I believe it can be mastered to a race winning level.
    I think it will be used before long in the Moth class and not long after that in the R Class.
     
  5. Chris Ostlind

    Chris Ostlind Previous Member


    Yes, Doug, Vapid.... because that's exactly what it is right now. You know the truth here, my boy. Take a look around you and pay very close attention to the foiling boats that are in production, Essentially, you've got Prowler, Bladerider and the Mach2. Yeah there are lesser players but they are onesy/twosey outfits right now. Of these players, which production foilers are actually using a manual control system right this moment for their boats?

    I know the answer if you are reluctant to look bad in spite of the boasting.

    Try ZERO

    Yep, that's right, this killer technology is batting exactly zero in the marketplace. Yet, the use of a manual control has been known for many years. Zero manufacturers who have the absolute best riders on their teams. Riders who would give their left stone to get an edge on their rivals. Not one major player in the bunch is interested in the manual system.

    Now, I wonder why that is so? Hmmmmmm?



    Get over it, please. They know about it, it's been tested a lot by guys who have that zeal and the verdict is.... not interested. If you like, I'll go over to SA and get the quotes from the manual control thread and the midship wand thread. Remember that one? You know, the one where you said that it was going to be the salvation of the Moth foiling movement. Something very much like you are saying here with this bit of manual cotton candy.

    So, make up your mind, will ya?





    Well, the claims are still unsubstantiated as far as the 8 year old boat that nobody else saw foiling. And then wonder of wonders, the boat that could foil just stopped being sailed and then BAM! it was taken apart and shuffled off in pieces.

    That manual control boat is your substance?

    You speak as if this were a seminal moment in your experience and yet.... there's not one photo, or video clip of this majestic foiling event of which you speak. Not one. One would think that the whole thing would have been documented as if it were the world turning over on its axis, the way you continuously speak of it for reference.

    Not one photo.
     
  6. Doug Lord

    Doug Lord Guest

    Manual Altitude Control of High Performance Monofoilers

    For those designers and experimenters interested in looking closer at manual altitude control here is a comment from Tom Speer ,post 355 of "Foiler Design". And I would like to hear from anyone with on the water manual foil control experience and/or experience with modelling it by computer or rc testing :
    -------------------
    " If you look at the conditions for stable flight, the forward foil must have a relatively higher heave stiffness than the rear foil, and the rear foil must cause a greater change in pitching moment with a change in angle of attack than the forward foil. This is why wand feedback to the forward foil and a fully submerged aft foil work so well together. The heave stiffness of the aft foil is virtually zero, so it does all the job of stabilizing the craft in pitch. The forward foil then is totally responsible for controlling the craft in heave.

    Manual control of altitude via the forward flap makes sense, since that is the surface that really controls heave. But the big difficulty is having enough control power to handle both the dynamic change in lift needed by the control system, and being able to trim out the change in lift due to speed. With direct gearing between the wand and flap and the boat flying at a constant pitch attitude, the only way for the control system to trim out the increase in speed with lift is to deflect the flap upward, and because of the gearing between flap and wand, this means flying higher.

    If the boat is trimmed bow down as the speed changes, then the reduced angle of attack will compensate for the speed and the boat can fly at its design height with the foil centered (on average). One way to get this pitch trim is with manual control of the stern flap. The speed changes less rapidly than flying through waves or even being hit by gusts. So pitch trim with speed makes sense for manual control.

    It might be possible to get some automatic speed trim by clever manipulation of the hinge moments on the rudder flap. Aircraft use a device called a "down spring" to augment their speed stability. A spring with a low spring constant is used to apply a near constant nose down force to the controls. This has to be trimmed out with the trim tab. But the force from the trim tab depends on speed. So as the speed increases, the tab effectiveness increases and moves the elevator in the nose-up direction. This makes the aircraft climb, which reduces the speed.

    The opposite could be applied to a hydrofoil. If the rudder flap were deflected upward with a spring, increasing speed would reduce the deflection. This would make the boat trim more bow down, reducing the flying height in much the same way as the manual pitch trim described above. You could also divide the rudder flap into two parts - one driven by the spring and the other under manual control.

    Naturally, the spring force would control the amount of automatic trim change. It's better to get the force from deflecting a long, weak spring a lot, than by deflecting a short, stiff spring. This makes a bungee cord ideal for the purpose.
    __________________
    Tom Speer "
     
  7. bistros

    bistros Previous Member

    Chris:

    Doug is a very troubled person, with some serious reality issues given his behavior over the past few years online. His complete lack of social radar and non-responsive method of dealing with reality make him impossible to reason with, and a very frustrating person to deal with.

    From history you know EXACTLY how Doug is going to respond to every situation. From history you know exactly what effect reason and logic will have on him - none, zippo, nada.

    Doug has not surprised me with a single thing he's written in five years. The single event that did raise my eyebrows is that Doug did manage to get his emotional outbursts under control at Sailing Anarchy enough to be allowed to rejoin posting. I honestly thought that controlling his emotions was too much of a challenge for him.

    Save your hairline and forget about him. I'm trying to. He is beneath you.

    --
    Bill
     
  8. alans
    Joined: May 2004
    Posts: 50
    Likes: 2, Points: 8, Legacy Rep: 27
    Location: Australia

    alans Alan

    To clarify a point and add to the debate(s). When David Lugg and I were developing his foiled int 14, we dismissed using any sort of add on device to measure height because it was clearly outside the class rules. Hence, we went the manual route. From my manned and unmanned flight background I was very well aware that it was necessary to have the CofG forward of the CofLift of the combined foil pair(wing and tail plane) for the aircraft to be aerodynamically stable and for man in the loop control of an aircraft via elevator to be satisfactory. This criterion limits aircraft to a relatively small CofG range. Once autopilot control is introduced and provided it be designed correctly for each aircraft type then the allowable CofG range can be extended well into the unstable region. Modern fly by wire fighters are deliberately designed to be “aerodynamically” unstable. This results in both wing and tailplane lifting in concert and hence an improved aerobatic performance. Aircraft are traditionally control in pitch via the elevator; using the elevator to change attitude and hence climb rate at when at the height required level out, again using elevator control. It transpires that one way to fly aircraft is the technique used in flying gliders and that is to use pitch attitude to control speed (mg sin theta is normally many time better at providing thrust than the propeller) and engine power to control rate of climb. I get off the subject! There are of course some aircraft, which are canard controlled, and unstable canard is superior to unstable elevator control when it comes to aerobatics.
    Stability is best understood by analysis of dynamic motion through differential equations, Laplace transforms and review of results in the complex plane or the frequency domain. When all the (4) roots of the denominator of the resulting transfer function are negative (i.e. in the left half plane) the system being analysed is stable. To achieve aerodynamic stability with a canard configured aircraft the forward flight surface is usually smaller than the wing and the CofG is somewhere near the leading edge of the wing. In developing the 14 this configuration was not further considered as we saw the incompatibility between the rig demanding a specific CofLateral resistance and the position that would be necessary for the main foil. In addition, in the early stage of developing the 14 manual control via flap was also ruled out in favour of a simpler engineering solution enabling control from out on wire on both tacks without having to graft a third arm onto the skipper. One outcome was that man in the loop control with an unstable configuration was not as difficult as in the aircraft case as the damping of any pitch perturbation is much better in water than in air and David was able to reduce the rudder foil area considerably from where we first started. Manual control will always necessitate more rudder foil area than automatic wand control via flap. There have been a few pilots capable of flying an unstable aircraft by they are rare. Another outcome is that manually flying the foiler was very exhilarating to the extent that the extra workload was not conducive to successful top end competitive racing.
    The questions are can a foiler i.e. moth be manually controlled via the flap on the forward foil and is a canard system feasible i.e. large rear foil smaller front foil. The answer is definitely yes. However, before investing a lot of efforts in proving this consider first that the existing wand to flap control is, from a control system stance, extremely robust. Because it is automatic and robust it is stable over (compared to an aircraft system) a very wide range of speeds and CofG positions. For those considering canard or manual control or both, it is possible to answer the questions precisely with mathematical analysis and this is the way any aircraft designer would go long before cutting metal and trialling the hardware. You cannot expect to again achieve Fastacraft success with “suck it and see”” add hoc” methods.
    Bottom line, I see manual control as a fun exercise but where class rules permit, automatic control as absolutely necessary for competitive racing. As far as canards are concerned, I cannot see a configuration that does not add wetted surface area and the two best ways of improving performance are to reduce all up weight, increase the span of the foils and reduce the total wetted surface area. Selection of foil sections and windage drag are secondary issues but become important as a class of foiler becomes or virtually becomes one design. On the question of all up weight, I think the international moth guys should consider weight correctors so that the heavier guys have some chance of winning in light to moderate conditions.
     
  9. Doug Lord

    Doug Lord Guest

    High Performance Monofoilers Manual Control

    Thanks, Alan. I had such interesting results with my 16' foiler with manual control and with three different models that I think the "“suck it and see”” add hoc” method" holds some promise-at least for me on the new boat. The major change I will make is to add simultaneous control of the main foil and rudder foil with 100% adjustable mixing. I have a hunch ,based on the first boat and models, that this could make a major difference in terms of improving control and "feel". It is so simple to try that nothing is lost if it doesn't work as well as I think it can.
    At any rate, the mathematical analysis of the system is beyond my skill set-and experimentation is not-we'll see.
     
  10. sigurd
    Joined: Jun 2004
    Posts: 827
    Likes: 8, Points: 18, Legacy Rep: 65
    Location: norway

    sigurd Pompuous Pangolin

    the moth auto system seems robust but they do crash at times. i've seen vids where the front foil surfaces and ventilates and then crashes. A manual control override could be faster than moving your body - if this issue (if it is an issue?) cannot be fixed by more gain in the wand system? Or is the (perceived) problem due to no more AoA/flap range in the main foil?

    Why does a canard system have more area?
     
  11. alans
    Joined: May 2004
    Posts: 50
    Likes: 2, Points: 8, Legacy Rep: 27
    Location: Australia

    alans Alan

    Doug

    I don't say suck it at see will not work ; this technique has not been applied to aircraft for near a 100 years. However S and S is much more fun specially if you strike gold. Go for It.

    alans
     
  12. Doug Lord

    Doug Lord Guest

    High Performance Monofoiler Design

    Alan, just to help me understand more: a wand moves the mainfoil flap several times a second in waves-if you had an altitude control system that eliminated that flap movement would there be a significant reduction in drag?
     
  13. alans
    Joined: May 2004
    Posts: 50
    Likes: 2, Points: 8, Legacy Rep: 27
    Location: Australia

    alans Alan

    Doug
    The simple answer is yes, but once you are at speed the increase in induced drag is small and the "flapping" contribution is about 10% of the small number. What the best solution is, is a much more complex question? The answer can be found by running many hours of simulationor or many hours of sailing an instrumented boat either in a test tank or the sea. Reducing the gear ratio wand to flap will reduce the magnitude of the osscilation but possibly also increase the drag of both foils. The drag is also effected by the heavy motion of the water the foils are running through. For a longer wave maitaining a constant angle of attack relative to the water motion will be the lowest drag solution. In short chop the reverse will be true. It is a good thesis topic for a stability and control masters student. The solution will require independen control of height bias and wand to flap gearing in order to manage the wide range of conditions experienced.
     
  14. Doug Lord

    Doug Lord Guest


  15. Doug Lord

    Doug Lord Guest

    High Performance Foilers:"..one of the premier dinghy classes.."

    The foiling 49er has finally flown under sail! More coming up....
     
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