Crossbow fl

Discussion in 'Sailboats' started by Doug Lord, Jun 21, 2012.

  1. Baltic Bandit

    Baltic Bandit Previous Member

    So if righting moment is the be all and end all to generate SA/D - what does a Circular cockpit do other than decrease RM as you move from the extreme outer points to different positions which in a circular cockpit are necessarily closer to midships and hence generate less RM?
  2. Doug Lord
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    Doug Lord Flight Ready

    Crossbow fl-Original and New

    Here is a comparative shot of both versions of the boat(done to the same scale) clearly showing the larger rig, longer hull and higher freeboard of the new version. Beam and hull draft do not change.
    I'm really liking the the mods and the performance gain for relatively little modification-at least from a cost standpoint it's not much of a difference. No significant weight difference. The rotating seat makes it all possible by allowing a lot more RM from the same crew weight.
    Summary of the probable changes: (see post 177 with new version changes in red)
    1) new hull is one foot longer,
    2) upwind SA is increased by 30 sq.ft plus the wing mast,
    3) room for Trapeze Movable Ballast System to slide fore and aft two feet.
    4) SCP/boat weight=.3 (up from .2 and at the threshhold for upwind planing.) SCP/boat weight including the RM from the DSS foil upwind increases the ratio to .34 )
    5) SA/D goes from 31.6 to 42.48 upwind.
    6) SA/ws goes from:
    --2.77/1 to 3.7/1
    --including DSS foil from 2.58/1 to 3.48/1
    7) DLR from 67 to 55.6
    8) RM from crew goes up four times(125 to 500 @ 10 degrees).

    click for better view--

    Attached Files:

    Last edited: Feb 24, 2014
  3. Baltic Bandit

    Baltic Bandit Previous Member

    Well that sailplan looks like a handful. With the heavy use of gaffs and essentially a telephone pole approach to the mast, this is going to be a high drag, hard to depower sail that would be a handful for a top-notch 18' skiff sheethand to manage, much less someone who's got some disabilities and is also having to control the trapwing with the same hand as the sheet hand.
  4. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Crossbow fl--Powered Up!

    UPDATED SUMMARY: 2/23/14
    This is a detailed summary of the boat and its systems-some of it posted once before. When I'm finished the MPX/SRT model this boat will again become priority #1. Funding will be sought and looks real good right now. I believe that this technology can open up a whole new world of singlehanded performance monohull sailing to people who might otherwise never get to experience a planing reach with an asy flying! There is nothing like it anywhere and it would pioneer a whole new way to sail a fast monohull dinghy.
    IMPORTANT: the decision has been made to go with the powered up version of the Crossbow fl and this summary has been modified to reflect the changes described in the previous post. The rotating seat is the key to making the powered up version work and I'm now convinced that "we" can make it work-and work well.

    Crossbow fl

    Part 1--The key to this boat is the wing. The wing is sealed and allows ballast to slide side to side as the wing slides. The cg of the ballast(80lb) moves nominally 13' (slightly less in practice-about 12.5' in 3 seconds/ 4.17 feet per second/2.84mph) from the center line of the boat. Same weight movement as if the wing was 24' long! Trapeze wires support the wing and a carbon "apparatus" holds the wing at the center of the boat. This apparatus allows the wing to pivot around a vertical axis, and a fore an aft axis parallel to the centerline. Weight is adjustable in 9lb increments. Everything is adjustable including the speed of wing+ballast movement. The system will be electric with battery capacity enough for rapid and frequent movement of the ballast + wing over two 8 hour days w/o recharging. Capacity can be increased in special cases. Movement is controlled precisely by the crew using a joystick.
    Part 2- Another key to the boat is the buoyancy of the sealed wing and its wing tips which far exceeds the buoyancy required to float the ballast. That means the wing can be used to create righting moment( due to its buoyancy and not the ballast) in a knock down, righting the boat.
    Part 3- The prototype will test DSS foils which have worked very well -especially in the Quant 28 Sportboat(unparalleled race record) and in the Infinity 36. The foils will be used in an entirely new way -they will plug in rather than operate from a trunk in the boat. The other applications of DSS work in a trunk that allows the board to retract or partially retract. The new Quant 30 uses unique curved DSS foils that can be independently retracted and/or deployed. The Crossbow system allows the foils to be inserted and locked in individual trunks. The boat is designed to facillitate this by sailing at a 10 degree angle of heel keeping the windward foil clear of the water and reducing hull wetted surface. These foils appear to offer modest RM upwind and nothing short of tremendous RM off the wind. In a boat like this, the combination of DSS foils and the Trapeze Wing movable ballast system, offer lots of power to carry sail and planing performance with an extremely wide crew weight range. For DSS to be most effective, the hull must be designed specifically for it to allow the foils to be in the proper position when exiting the hull. The foils must be at least 1 chord below the surface at a 10 degree angle of heel.
    Part 4- One of the most important phases of the development of this concept and the refining of the Crossbow fl prototype design is complete-model testing. For over 10 years the concept of the Trapeze Power Ballast System has been extensively tested on numerous RC models as well as a few non-RC models. The results are conclusive: the system works and a prototype has an excellent chance of success.
    In different places in this forum an ongoing, uninformed minority lash out at model testing which is too bad. Julian Bethwaite, among many other's, has remarked that model testing saves time and money. Alain Thebault(Hydroptere), Dr. Sam Bradfield(Skat, Rave , Osprey and more), Greg Ketterman(Hobie Trifoiler and Longshot), Bill Burns(CBTFco), Hugh Welbourn(Dynamic Stability Systems), Yves Parlier(Mediatis Region Aquitaine ),Bernard Smith(40 knot sailboat), Paul Larsen(Sail Rocket) and many others have used RC model testing to test basic concepts and refine the design prior to building a full size prototype. It is one of the best ways to test-particularly so in regard to the Trapwing System.
    Testing the movable ballast system is one of the areas of RC model testing where the results can be 100% trusted and where the potential of the Trapeze Power Ballast System has been thoroughly tested. One difference in the model testing of the system is that the skipper has to have faster reactions than are required on the full size boat, since, as the system is scaled up reaction of the boat and the ballast take longer to happen. That means that the skipper of the RC boat has to have quicker reactions and more "anticipation" than the full size sailor on Crossbow-and also means that sailing a Trapeze Power Ballast System model is excellent preparation for sailing the full size boat.
    Part 5- The Rotating Seat- this is a system that will allow the skipper to sit facing the opposite side instead of facing forward like most small singlehanded keelboats do-and to be able to switch sides while remaining seated. I personally prefer to sail with the hiking stik in my aft hand and the sheet in my forward hand. On this boat the wing control/joystick will most probably be handled by the forward hand as well UNLESS there is a way to do it by using a twist grip on the extenstion tiller-but thats a ways off if it happens at all. The biggest advantage of the Rotating Seat is the fact that it increases the RM generated by the crew 4 times over what was possible with the fixed single or tilting seat both of which faced forward.The seat will be set up to be able to be moved manually or electrically.
    Part 6-The Development Team: (from post #1)

    - I retained the services of Eric Sponberg to help spot glaring errors and to help with engineering.
    - I retained Rick Loheed to build the DSS "plug-in" foils.
    - I'll use Falcon Marine, LLC to "carbonate" the hull and to provide a portion of an A Class Catamaran mast for the Crossbow(laid up for this boat out of his brand new mold). Matt McDonald does some of the finest work I've ever seen on the cats he builds.
    - I've retained Sharon Dixon of Rockledge Architectural to actually carve the hull of this boat from a couple of solid blocks of styrofoam. The "boxiness" of the shape reflects her capabilities-no compound curves-etc. Using this method and having Matt carbonate it saves above $1500 over having the boat built out of wood. UPDATE: Wood may play a greater role than originally intended but Sharons styro capabilities will still be vital for the large rub rail.
    - I've received a great deal of help from Hugh Welbourn in deciding on the foil section , placement of the foil , angle of incidence and other matters relevant to designing for a DSS system. This boat will use "plug-in" DSS foils that will be installed on the beach(or not) depending on conditions. Testing will be facillitated by simply leaving one foil off.
    - I'll use Rick Willoughby for design of the electrical system. Between Eric, myself and Rick we will choose a supplier in the states for the parts required for a first class, reliable Power Ballast System.


    Summary of Features and Specifications
    1) Self-bailing cockpit
    2) Boat rightable from 90+ degree knockdown by crew w/o crew movement using the wing regardless of the position of the sliding ballast.
    a. ballast wing is sealed and has buoyancy much greater than that required to float the ballast sliding inside.
    b. ballast+ wing can be moved manually or electrically faster than a crew on a trapeze could move.
    3) Rig utilizes modified rotating, A Class wing mast, sealed with masthead buoyancy to prevent turtling,
    4) Ballast wing pivots:
    a. to allow trailering
    b. to move ballast aft when required with wing extension.
    c. also pivots athwartship to keep weight low to windward and to keep lee side of wing clear of water.
    5) Ballast is adjustable in 10lb increments,
    6) Boat can be sailed off a beach,
    7) Boat features an asymetrical spinnaker, an underdeck spinnaker chute and retractable bow pole,
    8) Seating arrangement: (NEW) .
    a. The skipper will sit relatively low in the boat on a seat that will manually or electrically rotate 180 degrees. This will allow the skipper to steer with his or her aft hand and handle the single sheet and Trapeze Power Ballast system with their forward hand. For Class racing weight equal to the difference between 250lb. and the skippers weight will be carried in a ballast compartment under the seat. 250lb is the maximum crew weight for racing.
    9) Large, buoyant "spray rails" act to help provide a dry ride and knockdown recovery,
    10) Self-tending jib with variation of Swift solo single sheet system.
    11) Boat uses removable, "plug-in" DSS foils for greatly increased power to carry sail with speed.
    12) The new changes effectively "turbo" the boat even allowing for windward planing.
    13) Boat has an extremely wide crew weight range: approx 100lb to 250lb for normal sailing. All ratios are based on 250lb crew and would drastically improve with lighter crew weight. For class racing, it would be my desire to see a class adopt the maximum crew weight as standard with lighter crew carrying weight under the seat-or perhaps two "weight classes"-whatever it takes to encourage the widest participation.
    Specifications: (changes are to be expected)
    Hull length-15.6'
    Beam- 4.75'
    ---at waterline-3.75'
    Sail Area-(boat will use a carbon A Class wing mast from Matt McDonald/ Falcon Marine LLC, laid up specifically for this boat).
    --upwind- 161 sq.ft.
    -- downwind- 290 sq.ft.
    Weight-sailing weight w/o crew- 223lb which includes:
    --hull, rig, foils-124lb
    --Trapwing Ballast System:
    ---wing-21lb. @ 12'-16' length overall, pivots for transport, and moving weight aft.
    --- max ballast 78lb(8 pieces of lead-removable-.25" X 8" X 12"-about 9.72lb each)
    Max Crew weight: 250lb-boat is designed as a singlehander.
    All up sailing weight including crew-473lb
    DSS Foils: each 1.63 sq.ft.( 6" X 39") 6.5/1 aspect ratio, Welbourn section.
    Electrical System for moving ballast: Engineered by Rick Willoughby, who did the original "ballast mover" spread sheet.
    see Eric Sponbergs Design Ratio's PDF below
    --downwind- 76.78
    --3.48/1 including DSS foil
    SCP/Total weight= .3 and .34 if upwind RM from DSS foil is counted.


    Attached Files:

    Last edited: Feb 25, 2014
  5. Baltic Bandit

    Baltic Bandit Previous Member

    Ok for those who don't want to slog through the repeated post, the changes between this post and Doug's earlier post are

    1) that he's going to put the bigger and less controllable sailplan on the boat

    2) that he's going to increase the complexity by adding the rotating seat. (item #5, moving his team to item #6)

    No other changes
  6. Skyak
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    Skyak Senior Member

    A possible way forward

    based on your recent posts what you have are foils and the desire to make the boat that can use them. The hull that can use them is not that hard -marine ply with some reinforced areas. If you offered the foils as half the value of a boat build I think you would have no problem finding a builder. The resulting boat would be in your possession roughly half the year and in the builders possession roughly half the year. They might not even want the boat at all, just use a few weeks or months a year.

    A key item is that an able bodied builder/sailor will want to just shift his weight and not wait for the automated ballast shifter development. But the boat can easily have mounting points for both. While the boat is built, you build the wing development mule. With the boat in the water demonstrating performance, real measurements and demonstration of the wing mule, I think you will have what you need to go for funding the automated boat. The funding will be purely for adapting a performance boat to the disabled sailor -a worthy charitable cause.
  7. Doug Lord
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    Doug Lord Flight Ready

    Good thinking Skyak, but I won't make any deal that requires possession of the boat to change before all the development work is done and the boat proven. Afterwards, absolutely-in fact, in an earlier post I mentioned sailing in the EC or having someone else sail it. But only when she's ready.
    With the new sail area , the boat won't be able to be sailed in much wind without the Trapeze Movable Ballast System. We have a basic design for the system so it will be built as the boat is being built. And the DSS foils won't be much good without the RM provided by the system to get the boat moving fast enough for the foils to be effective. Also the Trapeze Movable Ballast System prevents the boat from capsizing and makes it self righting so it is critical for the safe handling of the boat. Everything has to work together to allow the boat to function well.
    Thanks for the ideas......
  8. Skyak
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    Skyak Senior Member

    What's important is recognizing that what you want from the boat and leaving plenty of room for value for the builder. The ultimate disposition of the boat could be donation to a disabled sailors asn. or it could revert to the builder after some period of time, or something else...

    This idea for designer/builder collaboration did not originate with your project. I have more design concepts than I can finish in my lifetime and my yard and garage are full. With all due respect you are older than I am and have less work and storage space. I have been toying with the idea of a site to bring builders together with sailors, recognizing that there are many prolific builders pushing the limits of spousal patience. Linking them with partners willing to pay for materials and do some work in return for majority use of the boat could get more projects going.
  9. Doug Lord
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    Doug Lord Flight Ready

    While I think you have a good idea it may not work for the Crossbow fl project
    for the reasons in my last post but also because there will likely be more than one company involved in building.
    If I go with EPS the hull will be computer cut by the Architectural firm and Falcon would do the carbonation.
    If I go with the 1/8" Okume, a guy that Eric has recommended will do the woodwork and, again, Falcon will do the carbonation.
    I'm leaning toward the wood version right now.
  10. Baltic Bandit

    Baltic Bandit Previous Member

    So what if there is a PLC controlling the cutter. what matters is the design. And with any new hull shape, unless you either have years of experience in lofting great hulls like Paul Bieker, or you are a CFD jock like Paul Bogataj, your basically rolling the dice on the behavior characteristics of the hull.

    And this is one area where models just do not scale directly to full sized boats.

    Furthermore its a massive violation of basic engineering principles to change too many things at once. there is no need for a new hull. An existing performance hull like a Laser II can be used to prove out the concept and iron out the bugs.

    In fact the first step would be to build a working model of the Trapwing bolted to a picnic bench table so that you can validate is motion. the need for a Hull design is years away.
  11. Doug Lord
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    Doug Lord Flight Ready

    I've had a suggestion that I like very much: first job in building the boat would be to build a full scale mock up of the rotating seat. So much of the
    new version of the boat depends on this thing working the way it is envisioned to work that the mock up is a great idea and will be done. After the MPX Test Model is complete, I'll build a model of the rotating seat to "flesh" it out which will help a great deal followed by building it full size.
    The powered up version of the boat will allow the concept to be well demonstrated-beyond a shadow of a doubt and it will be an exciting boat to sail for crews weighing around 100lb. on up to 250lb(under review). The key to that, of course, is seeing to it that the rotating seat can carry the required ballast so that the seat is always carrying the max "crew" weight.
    If the ballast, for a light crew, is not used (and the weight in the wing not increased-max 78lb with the standard system) the boat won't be able to be sailed properly-the ballast in the seat making up the difference between the lightest crew and max crew weight is essential for the best performance of the boat. Minimum crew weight will be adjusted ,if necessary, to insure that the proper ballast can be carried.
    I'm convinced that the wide crew weight range is one of the great advantages of the Crossbow concept but the RM equalization system is critical to making it viable.
  12. Baltic Bandit

    Baltic Bandit Previous Member

    Doug typically the first job in any engineering design is to get the fundamentals to work first. As far as I can tell the rotating seat does nothing to add RM and even if you mock it up completely, you will not be able to test it since you will not have a boat that is stable enough.

    Seems to me that this is a way to almost guarantee the project never reaches fruition.

    I strongly recommend that you mockup the Trapwing at a scale suitable for a Laser II hull
  13. motorbike
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    motorbike Senior Member

    Doug I don't understand your posts or your logic or reasoning. It seems you are using a lot of important sounding "buildy/designy words" without actually knowing anything at all about real world design and build processes.

    This craft is a prototype with more than one radical idea to prove in full size. I am not fazed by builder babble or designer babble or reference to this builder or that designer that you have "engaged" I suggest you get an existing hull and get the trapwing to work full size before anything else.

    In fact I suggest you go sailing on a skiff like a 49er and get some 1st hand experience rather than youtube or pond model experience before you commit disabled people to being launched at 20 kts into the main from your 21st century interpretation of a trebuchet.

    If you were serious about helping disabled sailors go fast on a stable dinghy like platform, this design is not really suitable, but it is an expensive, complicated Heath Robinson affair when you consider how much simpler the project would be if you used a cat.
  14. Doug Lord
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    Doug Lord Flight Ready

    I couldn't disagree more emphatically with you. You make statements about me that are false-you have ,apparently, no knowledge whatsoever of my experience but you're willing to speak as if you do! I've been sailing since I was 7 -I've sailed mostly high performance boats all my life and have designed and built numerous boats including production boats I designed and did the tooling for that sold over 300 units.
    When you approach me with that kind of attitude there is nothing really to say except that you're wrong and further, that you don't know what you're talking about!
    And let me tell you: people with far greater experience than you evidently have, given your uninformed comments, have praised the boat and concept. It is potentially a great boat for disabled and physically restricted sailors to enjoy fast, high performance monohull sailing in a self-righting speed boat the likes of which doesn't exist right now.
    When you even mention a cat in the same breath as disabled sailors you give yourself away as woefully uninformed and completely without a clue as to the advantages the Crossbow fl offers in safety coupled with high performance.
    Sorry pal, but you got it completely wrong!

  15. Baltic Bandit

    Baltic Bandit Previous Member

    Doug - do you have any formal training in any engineering discipline whatsoever? If so to what level?

    what is the last high performance craft that you sailed and when did you sail it?

    What is the last high performance monohull that you sailed and when did you sail it?
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