Crossbow fl

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Thanks, sharpii-I'll give it some thought.

 

Doug:

Best wishes with your medical issues. Keeping the vision of a project in my head has helped me with rehab/recovery in the past. Rather than focusing on my problems of the day, I focus on better days ahead. I just keep repeating to myself "I have to get through today to get to where I want to be tomorrow".

I have to say although I appreciate your determination to go "all in" and do everything at once, I have some reservations. Dr. Speer's approach works well when you are a third party directing the money of the absurdly wealthy and unlimited paid labour of other people, but most of us are limited in one or both of the above. As frequently mentioned here I'm a fan of breaking projects into reachable milestones and achievable goals, rather than bringing too many variables and concepts into play at once.

At this point in my life I am sharply aware of every clock tick and the importance of a good ground game. "Hail Mary" development, much like Hail Mary football is the preferred strategy of the doomed.

I for one would rather see you on the water sooner, incrementally refining and proving one concept at a time than never getting wet with an uncompleted massive project and the time clock (or money clock) run out.

--
CutOnce

 

Over the last few months I've come to realize that the whole "essence" of this project is the Trapwing movable ballast system. I think, for my own sake and for the sake of others who could benefit once this system is proven, that I need to focus on the original concept 100%.
I believe that this concept has the potential of allowing physically restricted/disabled people to enjoy planing dinghy performance in a self-righting boat whose safety meets or exceeds the safety standards found in any other singlehander used for disabled/physically restricted sailing. Those same people have no self-righting planing dinghy available to them anywhere on the planet.
It's very important to me to try to prove that this system is viable for a full size performance dinghy.

 

Just found out from Julian Bethwaite that the SKUD 18 two person disabled lead assisted dinghy is now using an electro-hydraulic system to cant the skipper to windward. This is the first use of a system like this on a dinghy or boat under 20' that I'm familiar with-pretty cool!

 

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A remarkable thing happened 3 weeks ago-I woke up one morning with zero pain -1st time in 7+ months. I played it easy-not believing that anything really changed or could have changed!! But I remain 100% pain free today. I saw my Doctor in Orlando a week ago and the surgeon in Melbourne
today. Nobody has any idea how that could be since I've had a high level of agony since June. Now it's gone, but how? why? No answers. Last week knowing I was going to see the surgeon today I went out in the shop and rolled my 16 footer out of the garage ,moved a couple of big boxes and folded up a 50lb table and carried into the house to facillitate building the SRT model. I figured that: 1) I'd wake up in agony the next day, 2) I'd wake up with no pain. No pain. Might have been stupid to do that in some ways but I have the opportunity to have this back operation 100% paid for by Voc Rehab and I don't want to lose that opportunity. But the surgeon rules and after putting me thru some bending and walking tests today he said the only reason for this operation is to relieve pain and since I have no pain-no operation.
He said he would explain that to Voc Rehab and hopefully I won't lose out they'll just put it on standby for a few months.
I'm going to go ahead and finish the SRT model(http://www.boatdesign.net/forums/mu...lf-righting-trimaran-test-model-36058-18.html ) since I just spent about 3 grand on it. I intended to do it during my recovery from the operation , now I'll be at it half a day+ every day until its done.. And next, God willing, is the Crossbow fl.

 

Glad to hear the news.

I would try to be careful to not put the back at risk (lift with the legs and all of that stuff) but at the same time consider staying active enough to retain/recover muscle health.

We can just hope the back stays good and you eventually get the chance to sail at least one more new full sized prototype.

 

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Thanks, Paul! I "tested" my back-maybe foolishly- but it has given me a lot of confidence. Fl Voc rehab says they'll help if things go bad so I feel good.
One less big problem -at least for now.......

 

Based on my own experiences I would suggest going to a physiotherapist, explain the situation and get some exercises, then do them exactly as prescribed.

Great news Doug, welcome to the ranks of the pain free! I too am getting used to normality after about 2 years fighting off poly-myalgia rheumatica, which is very painful and potentially dangerous as the body is destroying protein; I understand eventually it would have chewed through my organs and then . . . Anyway it took a while to find the right specialist and after a battery of tests I got the medication I needed. I just stopped it after 15 months of interesting side-effects, looking good so far, now to get my strength up and weight down, plus some flexibility from doing the exercises I got from the physio.

Glad you seem to have made it through your problem too!

 

Thanks, Terry! and good luck.....

 

This is a detailed summary of the boat and its systems. When I'm finished the SRT model(getting close) this boat will again become priority #1. I may have to try one of the "crowd sourcing" fund raising groups but I'm going to go for it.

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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 14' (slightly less in practice) from the center line of the boat. Same weight movement as if the wing was 28' 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 2 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 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, where the crew weight has little to no effect on RM, 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.

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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 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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Summary of features and specs:
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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) Skipper sits in a sliding seat that can also tilt 10 degrees each side so the the skipper sits upright at the designed angle of heel of 10 degrees. Seat can be fixed in center so it won't tilt while still retaining the capability of sliding fore and aft.( see illustration below)
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) Boat can be "turboed" to be capable of upwind planing with addition of a maximum of 62lb ballast and a 150 sq.ft. rig.
13) Boat has 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)
LOA-14.6'
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- 120 sq.ft.
-- downwind- 240 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(crew weight range is exceptionally wide on this type of boat since the crew contributes very little to righting moment)
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-
DLR=67
SA/D=
--upwind-31.6
--downwind- 63.3
SCP/Total weight= .2
Note 1: a ratio of at least .3 is required for upwind planing and could be achieved on this boat by adding 62 lb. to the ballast tray in the wing. Nice "turbo" idea for sometime as long as the buoyancy of the wing is enough for righting.
Note 2: an interesting side note to the application of Bethwaites ratio to this boat is that it is not clear to me that proper "credit" is given to the lift potential of the DSS foils. For the upwind RM calculation the lift from the foil was calculated based on a speed of slightly over 5 knots. If the upwind speed were, say, 8 knots the ratio would increase to .27+. A speed of 10 knots with the 250lb crew changes the ratio to .295 and with a 180lb crew that ratio changes to .35.
That adds a very interesting twist to testing in that it appears that reaching off a bit to increase speed may pay much larger than normal benefits on this boat. Speed increases the lift on the DSS foil expoentially and therefore increases RM dramatically. Sounds like fun to me.....
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Note on ballast mover-each segment is 1.5 seconds.

Pictures-click--

 

I'm root'n for you, Doug.
My advise is to partner with someone interested in racing it in Water Tribe events.

 

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I've been thinking of doing the Everglades Challenge or letting someone else use the boat for that-shallow draft makes it ideal and the DSS foils still work in shallow water!

 

I wish you the best of luck.

Though I have to admit I like your SRT idea better.

It seems to do almost as much with far less complexity.

What you are attempting to do is similar to what bomber and fighter designers attempted to do with 'swing wings'.

In theory, the concept worked.

In models, the concept worked.

In full size, the concept worked, but its performance gains were disappointing.

It was abandoned on all fighter designs and retained only for the B-1 bomber (which, IIRC, itself has been discontinued).

The problem ended up being weight issues

 

sharpii2, I like them both. I don't see the Crossbow as complex-the electric system it uses is fairly simple compared to systems available for disabled sailing. The electrics used in that application have proven to be rugged and well manered in the marine environment. Moving the weight electrically is the only way for some users but I'm going to test manual movement as well. A mostly in shape person may be able to move the wing by hand. 90% of the usage will be sliding a weight with very low friction track and wing retainer.
I don't think the whole potential of this thing is known yet-there is a lot to find out. One thing I did find out for sure was that, during model testing, using a joystick to move the weight was fun-big time fun!
So we'll see.......

 

My main concern was not the electrical complexity (you only need one motor) but the structural and mechanical complexity.

Moving the wing side to side is one thing. being able to pivot it aft as well is quite another.

It would be relatively easy to have the weight creep outboard as the wing is extended. Two lines, two pulleys in the wing, and one hard attachment point on the hull would do it. When the wing is centered over the hull, the weight would be as well. As the wing is extended to port, say, the port line tightens and the starboard line loosens, pulling the weight to port. When the wing is fully extended to port, the weight will be out to its furthest limit.

Simple enough.

But making this whole business pivotable implies a rotating sub structure which holds the wing and wing extension motor.

This sub structure must somehow be locked in place, once the boat is under way. Otherwise, wave impacts may cause it to pivot aft at the worst possible time.

I can see two reasons why you might want this rig to pivot aft:
One, so it can comply with maximum width trailering regulations, and
Two, so the skipper can move the boat's CG aft.

If you are mainly interested in the former, a simply two position locking system can be set up.

If you are interested in the latter, it may be simpler to put the skipper's seat on a moveable track and move him fore and aft, instead of the ballast.

Just thinking out loud.

Best of luck.