Dominion 2-HW ,a Self-Righting Foiling RC Keelboat/ One-off Design & Build Project - Page 4 - RC Groups
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Oct 01, 2015, 10:05 PM
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DLord's Avatar

Foiling RC Keelboat Scow


Did stability calcs today to find out how much pressure it will take to fly the windward part of the hull with the movable weight centered and it is: .11 lb/sq.ft. on 11.9 sq.ft*. of sail("A" rig) which corresponds to a 5 mph wind-and that is ideal. That is also the wind speed that the boat is designed to start foiling.
One of the cool things about Hugh Welbourns foiling system is that the foils don't only lift the whole boat, they create tremendous additional righting moment(RM) because the center of lift on the new boat is about one foot to leeward of the center of the boat. It's unique to the DSS system that he invented and these foils are a refined version of the original invention.
* UPDATED 10/24/15

Illustration from Hugh Welbourn(lift and WL by DL) :

Last edited by DLord; Oct 24, 2015 at 11:00 AM.
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Oct 02, 2015, 03:59 PM
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Dick L.'s Avatar
Yeah, Doug - about 20 of these in a nice strong breeze and at the starting line. If the starboard foil doesn't take out the committee boat/starboard line end float, then I think hitting about 10-15 will open up the port boat like using a can opener or box knife. This IS NOT a class for sailors who like to barge at starts .... or tight mark roundings. !!!!

There is a reason most race boats using curved boards have the tips in side or under the hull - not sticking out like an airplane wing.
Oct 02, 2015, 04:20 PM
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Foiling RC Keelboat Scow


Right, plenty of real time incentive to keep clear of other boats, the marks or the committee boat.
Oct 02, 2015, 04:28 PM
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I think the famous French yachtsman Marcel Chevalier used something similar to this.
Oct 02, 2015, 04:53 PM
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DLord's Avatar
Right-he must have been at the cutting edge......... https://en.wikipedia.org/wiki/Marcel_Chevalier
Last edited by DLord; Oct 02, 2015 at 05:49 PM.
Oct 02, 2015, 05:08 PM
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Foiling RC Keelboat Scow--DSS


There are dozens of DSS* boats with foils that stick out from the side racing all over the world. All of them, including the Q23 have retractable boards.
It's still up in the air whether or not the model will have retractable foils.
* Dynamic Stability System invented by Hugh Welbourn.
Oct 02, 2015, 06:00 PM
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Dick L.'s Avatar
Not too many of these are round-the-buoy type of racers. If you have a rather unlimited starting line length and spread them all over the ocean, I see no problems, but for R/C sailing ( which this forum is all about) I'm not so sure it makes much sense - like trying to race a foiler in a weed infested pond instead of an ocean.
Oct 03, 2015, 04:00 PM
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DLord's Avatar

Foiling RC Keelboat Scow


SEE Post 66 which supercedes this post with Sailplan 3-10/24/15
==========
Here is the sailplan. Sail area may be decreased or increased at any time as the design progresses. The rig may be reefable so multiple rigs wouldn't be required.
The layout shown below is designed to have the quarter chord of the main foil line up with the mast-though it will be adjustable. The mainfoils are designed to lift 77% of the load, either singly or together with 23%, initially, on the rudder T-foil. The Trapeze Power Ballast System will carry up to 2lb and move F&A as well as side to side. The boat will be self-righting. The rotating carbon gaff includes an adjustable upper outhaul. The gaff may be changed if I determine that the boat needs masthead buoyancy.

Sailplan 2, 10/4/15

Last edited by DLord; Oct 24, 2015 at 11:05 AM.
Oct 04, 2015, 12:08 PM
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Foiling RC Keelboat Scow


This post is updated in post 67, next page.

A bit more detail with Sailplan 2:
1) Max heeling moment before depowering= about 11.67 ft.lb.
--
2) Max wind before depowering= about 9.5mph(8.26 knots)
After depowering with increased wind, the rig will be reefed or a "B" rig will be used.
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3) Maximum righting moment=11.77 ft.lb..This occurs with the Trapeze Power Ballast System fully extended to windward and the boat at a 9.5 degree angle of heel.

For reference:
a-about the same RM as a 6lb square Mini 40 trimaran,
--
b-2.44 times the RM of a Marblehead heeled 30 degrees with a 22" fin(from the boats CB) and a 7lb bulb.
Last edited by DLord; Oct 24, 2015 at 11:10 AM.
Oct 04, 2015, 05:04 PM
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Foiling RC Keelboat Scow


This model can be sailed with or without its hydrofoils, so here are the SA/ws(sail area divided by wetted surface) ratios for various configurations. Wetted surface considers both sides of every immersed foil:
1) Static-no main foils(includes rudder T-foil): 3.37/1
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2) Static-all foils wet: 2.71/1
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3) Flying: 12/1
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As soon as the boat begins to move the ratio changes for the better up to the least wetted surface when flying.
Foil areas are tentative and based on a foil loading of .188lb/sq.in. for the main foils. This is the loading that allows the boat to takeoff in a 5mph wind as well as to have high speed potential.
My first RC foiler, the F3, used this same loading and took off in a 5 mph wind and was clocked at 12mph in that breeze. She was was clocked at 18mph + in a 22mph wind reefed maximum. The Fire Arrow does the same thing but we don't know her top speed yet. Initially, she did twice wind speed in a 5mph breeze on her first day of full flying.
Next job is to design the foils.........
Last edited by DLord; Oct 10, 2015 at 10:37 AM.
Oct 06, 2015, 07:24 PM
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Foiling RC Keelboat Scow


The foils will be 16.5" span from the bottom of the hull to the tip with an 8- 9% t/c ratio. Chord will be constant at 1.75". The section will probably be symmetrical for the first couple of inches(below the boat) transitioning to an asymmetrical section. Area of one side is 28.875 sq.in.. One foil will be able to carry 77% of the load which at 7lb displacement is 5.39lb. Foil loading then will be .187lb/sq.in.. Initial foil loading(both foils) before takeoff will be around half that.
Foils will not be retractable but will be removable. The boat can be sailed in real light air(under 5mph) w/o them. Rake will be manually adjustable. There may be some twist to the foil over a portion of the span -maybe as much as 3 degrees-still working on that.

Last edited by DLord; Oct 10, 2015 at 10:36 AM.
Oct 08, 2015, 08:56 PM
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Quant 23-Worlds First Foiling Keelboat


Very informative article here from Yachting World:
http://www.yachtingworld.com/yachts-...keelboat-67953

Excerpt:

“The idea behind it is simply a boat that Joe Bloggs can leap into and ten minutes later he’s flying, without having to learn a whole myriad of complicated systems, loads of adjustments or anything like that,” declares Welbourn, agreeing that the boat could be described as a ‘gentleman’s foiler’.

In line with this ethos, the boat is very simple to foil. Yes, it is possible to change the rake of both the rudder T-foil and the main DSS foil by five degrees, but both the boat and its foil are designed so that these don’t need active controls such as rake as you typically find on other foils. During the 12 years he spent in R&D on DSS Welbourn has come up with a secret blend of variable foil section, positioning, rake, etc, so that as he puts it: “You let the boat do the work for you.”

Saying this, the Quant 23’s foil configuration does allow different modes of sailing, depending on what is required. It can be sailed without the foils, purely as a scow keelboat. With the foils fitted, but not fully lowered the boat can sail in displacement mode yet still with the usual DSS benefits of added righting moment, or the foil can be fully lowered (by a further 300mm) for full foiling mode.

The all-important aspects of ride height and heave stability require no user intervention. Depending on the point of sail and heel angle, the DSS foil will reduce its lift from either the inboard or outboard end of the foil the more it lifts out of the water as the boat accelerates, in a similar way to a V-type foil."


Specs:

LOA 23'11"/ 7m
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Beam 6'3"/1.9m
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SA:
a. upwind 344sq.ft./32sq.m
b.downwind 646 sq.ft./ 60sq.m
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Boat Weight 584lb / 265.4kg
a. sailing displacement +2--3 crew
b. bulb 143lb/ 64kg



Last edited by DLord; Oct 08, 2015 at 09:26 PM.
Oct 09, 2015, 11:35 AM
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Just out of curiosity I wanted to compare the SA (upwind only) and sailing displacement(with 3- 175lb crew) scaled down with the actual figures for the model. The SA varies as the square of length and displacement varies as the cube of length. SA on the model is only suitable up to around 9mph wind( 7.82knots). Above that the rig has to be depowered and/or reefed. Hopefully, we'll have enough sail area to foil in a 5mph breeze.

1) Upwind SA:
a. Q23-344sq.ft
b. FKS -10.45sq.ft. (actual 11.9sq.ft/1713 sq.in..)UPDATED: 10/24/15
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2) Sailing Displacement:
a. Q23-1109lb (584lb boat weight + 3-175lb crew)
b. FKS-5.87lb (actual 8lb.(target))UPDATED: 10/24/15
-------
FKS=Dominion IIRC(UPDATED: 10/24/15
Last edited by DLord; Oct 24, 2015 at 10:49 AM.
Oct 12, 2015, 08:20 PM
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FKS(Foiling RC Keelboat Scow)


This show is about to get good: I'll be ordering all the balsa and glue on Wednesday from National Balsa and getting the 3/4" X 2' X 4' building board from ACE Hardware. Hopefully, I can find an untwisted straight board. If not I'll have to screw it down to my existing table. All bulkheads have been traced and reduced at the "hulls" for 1/8" planking. And reduced where necessary for 1/16" sheets for the deck and cross structure.
I'm going to glass the balsa with 4oz. "S" glass and the foils will all be made with carbon fiber.I have a left over fin mold for the keel and I may have a mold for the rudder and rudder T-foil. I'll have to make two one-off molds for the main foils. Part of the cross structure aft may be open like on a "real" cat but done here just for lightness. I have the mast and main & jib booms and may have enough winches/servos to move everything but I'm not sure about that. One glaring thing I don't have is any of the ceramic molds I had for some of my production boats to use for the keel bulb. I'll have to try to find a 2lb long, skinny bulb someplace. Any ideas would be appreciated-I've looked all over so far with no luck.
Last edited by DLord; Oct 14, 2015 at 04:19 PM.
Oct 14, 2015, 11:24 AM
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Foiling RC Keelboat Scow


Just got the building board from Ace-2' X 4' X 3/4" which makes it 2" shorter than the boat. So II'll add a piece to one end to bring it up to 51". It's excellent quality and not bent or twisted.
I'll order the balsa and glue in an hour or so.....
-----
Update- just ordered $150 worth of balsa from National Balsa-that should complete the boat and the foil molds. Also ordered a .875" diameter,2.95lb cast lead rod from here: http://www.rotometals.com/product-p/...m?1=1&CartID=0
By the time it's shaped it will be around 2lb or so. Price was $10 for the rod and the same for shipping.
Last edited by DLord; Oct 14, 2015 at 03:09 PM.


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