High Performance MPX Foil/Self-righting Trimaran-The Test Model

I'll second that!

Anyone who is as obsessed with sailing as fast as Doug wants to go is ok in my book!

 

You guys are allright!

UPDATE- there is a bit of news: I got the specs to my sailmaker for a quote on the SRT sails. He has made sails for me for around 10 years including model sails and the sails for the 16 foot aeroSKIFF foiler which will serve as the first rig on the full size version of the SRT. The model sails will reflect a max SA of 350 sq.ft. on the full size boat and be reefable by removing the jib and rolling up the main(secured by velcro). This is a system that was first used on the F3. The idea is maximum power for light air with the ability to configure the boat for heavier conditions. Still tied up with Real work for the rest of this week(probably) but then back to the boat.

Sails Scott has made:

 

High Performance Self-Righting Trimaran: The Test Model

Did a full size layout today to experiment with crossarm dihedral, ama clearance and mainhull sailing angle. Here are some notes that include some changes:
1) Overall beam of model=79.875"(6.65')
------------fullsize tri= 23.7'
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2) Beam = 1.31 times length
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3) ama clearance with boat level= 4.25"(model), 15"(full size),
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4) Designed max sailing angle with mainhull 2.5" (9"full size) in air=12 degrees(8 degrees when ama foil kicks in),
-----------windward ama 13.5"(model),4' fullsize clear at this angle
-----------mainhull clearance more than doubles as lee foil kicks in
-----------will go with an experimental initial(ama bottom on water) angle of 18 degrees(13 degrees with foil working)
-----------sailing angle is controlled by dual "wands"(used one at a time) and can be set to maintain the two angles(one at a time) above by controlling the flap on the main foil which allows the foil to lift up or pull down.
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5) Mainhull can heel enough before ama touches to reduce wetted surface in light air,
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6) Ama foil does NOT have to be retracted tack to tack due to high dihedral!
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7) Ama dihedral coupled with the buoyancy in the "curved piece" is critical to the "self-righting" capability of the boat.

 

Surprise, surprise!

I've been a fan of Hugh Welbourn and his DSS foil system for years and we have e-mailed back and forth for some time. The other day he e-mailed that his sister in law lives on Cocoa Beach and he was coming to visit-and would I like to get together(!). So we did today at my place and we talked boats for an hour and a half. I showed him the SRT and explained the MPX foil system.
He thought the concept was great and especially thought the MPX system was "really good thinking". Needless to say I was thrilled that he thought so highly of the theory behind the boat!
What a great guy-one of the modern pioneers in the application of foil technology to sailboats.

Pix: Hugh holding the main hull of the model-

click on image-

 

Awesome!

 

Thanks, Raps...

 

ETA until launch? I am looking forward to seeing it go

 

High Performance Self-Righting Trimaran

Absolutely no idea. Real Life keeps slowing things down. As soon as I can-I'm anxious to see it fly!

 

You are not the only one who wants to see it fly! There is at least a couple of people here in forum land who would love to see this Mad Scientist Machine Fly!

 

High Performance Self-Righting Trimaran: The Test Model

Updates on mainfoil:

1) Main foil: liftoff-
a. Fullsize-7.6 knots with ballast; 6.5 knots w/o ballast
b. Model- 5.6 knots with ballast; 4.6 knots w/o ballast
c. Mainfoil area-4.1 sq.ft.(46.7sq.in model)
d. Main foil loading(fullsize)-max 146.34 lb. per sq.ft. @ takeoff-foil begins to unload immediately after takeoff.
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Is the ballast removable or fixed?

 

High Performance Self-Righting Trimaran: the Test Model

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On the model, the ballast will be removable by just changing out the main t-foil. Initially, the ballast will be "clipped" on to the daggerboard for static self-righting tests. That could save some time because I'd only have to build one t-foil so I could get to the MPX part of the testing under sail quickly. If the boat passes the static self-righting test then after the MPX foil testing I'd build the second t-foil with the ballast at the juncture of the daggerboard and mainfoil. Then the two could be easily swapped out.

 

High Performance Self-Righting Trimaran: The Test Model

Update on Curved Ama Foil:

Curved ama foil notes:
a. Decision: this foil, like all others, will be a symetrical section. Reason-I will be doing experiments that will require this foil to lift vertically up and down.
b. Curved foil is designed to support 100% of the weight of the boat. The model version will do this at 6 knots. The full size foil will do this at 13 knots.
This is key to the "MPX" system because when this foil is fully loaded the mainfoil is unloaded and the mainfoil and rudder foil 100% control pitch/ heave. Of course, when this happens is fully adjustable.
c. Overall length of curved foil is 7.25' fullsize( 24.5" model). At max deployment, 5.8' of foil are under the boat(19.5" model). Max draft for curved foil at max deployment with ama bottom at surface is 2.5'( 8.5" model)
d. When fully deployed full size, nominal vertical lifting portion of foil is 4'(of the 5.8' of foil under the ama). Chord is .83'. Same proportions on model.
e. Curved foil loading full size will vary from about 175lb.per sq.ft. to around 280lb. per sq.ft. while supporting the total all-up weight of 750 lb. because the foil will have less area in the water as speed increases. This is completely adjustable since immersed area is variable(board can be retracted in increments) and angle of incidence of the lifting portion of the foil is fully adjustable. Note: because of the unique design of this foil system the main foil is unloaded when this foil is fully loaded.

Picture: "lofted" model foil-drawing done full size to facillitate building plug and as a double-check/update to original design(shown earlier)-red line is CL of foil:
click on image-

 

any news?

 

No. Still bogged down with "Real" work.