Crossbow fl

I thought it was an equity site.

Rav V is a very interesting boat. On another thread I was saying the V sail rig could work well and got abused. I wish they had a prototype.

 

Crossbow fl---new type DSS "L" foil

A few weeks ago I spotted a new type of DSS foil in a post on SA. I didn't think it could be Hugh Welbourn because the foil was a retractable "L" type foil with the vertical being used for lateral resistance. I had learned , from Greg Ketterman, a few years ago that an "L" foil pointing outboard is a bad idea when the horizontal portion is used for vertical lift and the vertical portion is used for lateral resistance. The reason is because the foil then has high and low pressure on the same side and where they meet is a vortex generating drag. Greg tried it on his Trifoiler and the boat with the outward pointing foils was slower than the one with inward pointing foils. At any rate, Hugh responded in that thread that the illustration I had seen was not for every boat but was a refit to an older Open 60 and despite the drag associated with the pressure problem the result ,for that specific boat, was a net gain on the VPP.
So something about that kept nagging at me and I finally figured out that if the vertical fin was set at zero degrees to the flow while underway or close thereto there would be no lift and therefore no induced drag and no drag associated with high and low pressure on the same side most of the time. The Crossbow would still require a daggerboard for lateral resistance. Last night I e-mailed Hugh with the sketch below and he agreed that it was a good idea. What this means is that one of the biggest drawbacks I had considered to using DSS on a light planing dinghy has now been removed. The Crossbow hull was specifically designed so as to get the DSS foil low enough for it to work and it was just barely ok. Now, with my new found knowledge I can get the foil down significantly further with no hull design compromises due to DSS. Not only that but the potential performance increase just got better because the DSS foil can now lift the hull completely clear of the water if the designer wants it to. If choosing that option the boat would probably be better with a small rudder T-foil-something I was planing anyway. Another aspect of this concept that I just discovered is that the mostly horizontal foil can be angled so that it sails with a 10-15 degree up angle allowing the foil to unload the daggerboard a bit. This really opens up tremendous potential from a high performance perspective!
I'm still deciding on whether or not to build a large RC model of the boat to raise money and either way I'm likely to change the hull design.
The new version of the foil will still be retractable( vertically-not horizontally) but both foils would easily be removed.

Left illustration by Hugh Welbourn for a specific Open 60-vertical fin used for lateral resistance, Right illustration illustrates the basic concept of the DSS "L"/dinghy version in which the vertical fin is designed to work at zero degrees to the flow and develop no lateral resistance- both Hugh and I agree it should work well:

 

Crossbow fl ---Decisions

I've pretty much decided that my only viable option right now is to build a fully functional model of the Crossbow fl. I don't have the money to build a proto myself which would be ideal. And I don't want to attempt to raise money on the strength of the 24 year old(I think) models that worked real well but where there is no video of them sailing with the Trapeze Power Ballast System. This boat is a combination of new technology that people need to see function-and they will.
The design freedom the new version of DSS gives is just tremendous and will result in a completely new hull design. The current design was specifically done to suit the "old" version of DSS and that needs to change.
It will probably take a year or more to complete the model since I've got a fairly tough schedule as it is. I need to complete the cat and get to the point where I go sailing that model at least twice a week and Dan and I have some great video of the Fire Arrow yet to shoot.
I believe more strongly in the Crossbow than I ever have because of the design freedom the new foil enables and because I believe it can allow a new kind of sailing to a for a wide spectrum of people. The model seems to me to be the key in getting development started and since it will be fairly large(approximately 1/3 size) much of what is learned will have direct affect on the fullsize version. So there you have it-a major improvement to the boat and a plan to get going.

 

Long ago I told you that DSS is a keel boat thing and is not easy to apply to a dingy because the hull is too shallow. When the foil is too close to the surface it loses energy to wave creation. This L foil addresses that problem.

about project status:

I don't think that another model does anything to move the project forward to real prototype. If you are serious about a real boat you should demonstrate some real human size features. The ballast could easily be demonstrated in full size faster and for less cost than a model. You could mount it to a kayak with a sail to demonstrate even more. Building full size in marine ply would be a couple thousand tops and I am confident that could be crowd funded after the sail kayak. There are several treads going now that are sit-in sailers -your ballast shifter should be considered for all of these. Maybe you don't even need to be the one to create the first proto. You just need to contribute to one of those designs in exchange for the use, demonstration, testing video and whatever else you need for the crowd funding. Building another model just reinforces the notion it is not ready for a real boat.

 

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Hugh and I went over the problem when he was here. The current hull design takes into account the suggestions he made. The new DSS type has advantages and disadvantages-like everything. The current DSS foils were hand removable-the new version might be able to be as well-from a vertical trunk.
I'm not sure I agree about the model, but I'm really not sure. I'll know more when the cat using a Trapeze Power Ballast System sails in a month or so and I can decide if it will work with the extra weight needed for the Crossbow fl.
Frankly, I'm having "model building fatigue" and even if I build the model the beam of the hull is too much even at a 5' length to allow realistic planing*.
You've seen how people react to new technology by saying that "even if the model works that don't mean the full size boat will". There's only one real way to fight that level of ignorance and that is with a full size boat that does what the Crossbow fl is supposed to do. DSS of any type won't work on a canoe unless it was an IC.
* there is science behind that but also 55 years of sailing models
So right now, I'm up in the air. I've even considered (and am still considering) building my second RC Moth using the Fire Arrow foils and the TPBS from the cat. To that end I went to a quad site to see if I could get help adapting a quad stability system to the TPBS. Didn't get any real help except that everybody agreed that the system could work but needs a programmer to modify the software. Oh, well. Thanks for your suggestions.

 

So you understand that scale models are of limited value in convincing people -and not just people here -everywhere.

Engineering is using science and breaking down big problems into manageable tasks. That is what I think you need here. The ballast system is the real safety issue to prove here. It is also the unique feature. I still think you can simply start with a manual ballast system and show it working to safely stabilize a boat a human can sail. Then you can go for powering it, which is easy, then control that power.

DSS is Hugh's thing. It makes fast boats a bit faster. I don't think you need it to make something desirable. Think about the little AC and 2.4 boats -so much trouble and work to launch for limited performance. Over the surface ballast shifting could give similar but faster sailing in a boat that weighs 40 pounds and easily car tops. When the limits have been reached with the ballast shift, then you can offer DSS to the speed obsessed.

You suffer from "mission creep". You start with a good idea, but before you get to proving it out you add another feature, then another, and another.... Look at your trimaran from original concept to final. You started with the goal of not capsizing, you ended with the goal of flying and then flying better.

About "model building fatigue", I think you might be experiencing burnout and my question is if building something that gets you out sailing is a cure or do you need to step back from sailboats and do something completely different (which is the classic cure for burnout). If you look up self help for burnout they tell you to disconnect and do something fun that 'scares you'. When you have cleared work out of your head completely do you 'miss' it and want to go back?

FWIW a foiling RC moth would be cool but I just don't think it could be sailed without some on board control. And if you are going to on board control you might as well do the ballast full size. BTW did you ask the programming guys if they would be more interested working on a full size boat?

 

A word on the tri: it started out as a foiler with the ability to self-right. When I came up with the new foils it was my opinion that they were extremely significant and should be tested and proved as a priority. The ultimate goal has never changed-the boat is built just like it was originally conceived and the self-righting tests will still be performed. It was never a case of adding one thing after another-nothing was added at all-the only thing that changed was the sequence of testing and exact type of ama foil(UptiP vs "C").
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The guys on the quad site were made aware of the potential applications of the stabilization system. I was hoping a programmer would step up and say "I can do this using this basic hardware for x dollars" but that hasn't happened yet.
It's not a big deal since a lot of the fun of sailing the Crossbow-either model or full size would be adjusting the ballast.
But it would be a help to some potential handicapped users of the boat and would permit such things as an RC Moth. The Moth may be possible even without it if the new Trapeze Power Ballast System is powerful enough and fast enough which I'll know soon.
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PS- While there was no "mission creep" on the tri project after I started on the model, there has been a form of mission creep in the Crossbow FL design from the original to the souped up final version-from 14' to 15'.5' with more freeboard -mainly caused by my finding out that I couldn't sit in the center seat comfortably using a mock up. The higher rotating seat was a solution though so far not too satisfactory.
I'll probably revisit some ideas for a smaller version though I already went thru that pretty thoroughly and my basic feeling is that it should be done right or not at all.

 

Note that there is complete info on the Crossbow fl on the top of the previous page-specs, features etc. I believe in this concept and hope that a full size version can be built and tested.

 

Hi Doug,

I like your cross bow design.. would like to hear from you..

henry

hmccoy99@gmail.com

 

The new type of DSS foils(above) can work very well when designed to minimize lateral resistance when they are being used. Since I wrote the above material
Hugh and Michi have introduced the Quant 23-the first foiling keelboat in the history of mankind with unique foils that act as a traditional lifting foil and as a high aspect(wide) planing surface.
Quant 23 thread: http://www.boatdesign.net/forums/sailboats/quant-23-foiler-scow-53468.html

 

UPDATED SUMMARY: 4/5/16
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This is a detailed summary of the boat and its systems-some of it posted before. Funding will be sought and looks possible 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 . The rotating seat(along with the Trapeze Power Ballast System) is the key to making the powered up version work and I'm now convinced that "we" can make it work-and work well.

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Crossbow fl

Part 1--The key to this boat is the Trapeze Power Ballast System 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.
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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.
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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 facilitate 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.4/5/16--I'm looking at using a version of the foils mentioned above in post 257 which will operate differently than what I had originally planned.
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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 involved the function of the Trapeze Power Ballast System and not the electrical 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.
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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 a 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.
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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. Eric has since retired to go sailing but may still be able to help.
- 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 facilitated 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.

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Summary of Features and Specifications:
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Features:
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.
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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
--Trapeze Power 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.
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Ratios-
see Eric Sponbergs Design Ratio's PDF below
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DLR=55.6
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SA/D=
--upwind-42.48
--downwind- 76.78
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SA/ws-
--3.7/1
--3.48/1 including DSS foil
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SCP/Total weight= .3 and .34 if upwind RM from DSS foil is counted.
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Definitely decided to go with the "roto seat" which allows the crew to sit on the windward side and hold the tiller with their aft and and handle the main and Trapeze Power Ballast system with their forward hand.
The seat itself moves around a circular track. That gives leg room that would be eliminated if the seat was fixed in position.

Rough Sketch:

 

Crossbow fl 2017---- This boat has such great potential it needs to be seen now and again. At some point I will or someone else will build a fullsize prototype.

 

Crossbow fl 2017-- here are a group of pictures of models that have been tested over the last 20 years with a Trapeze Power Ballast System. The D2(Dominion 2-HW-4th picture down) a foiling keelboat/scow inspired by the original Dominion and Hugh Welbourns Quant 23 is the next model to use a Trapeze Power Ballast System:

 

Crossbow fl 2017-- based on another development, it seems it may be feasible to have radio control of the ballast inside the sealed wing-making the wing completely independent of the boat. It would use a portable transmitter and the whole system could be easily switched between different boats. Setup would be greatly simplified.