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

Looks a bit like something I built when I was a kid.. the tri popped onto its foils and planed! I may have a photograph somewhere.. unlikely

 

Doug, it is a neat looking boat but y o u a r e p r o c r a s t i n a t i n g.
C'mon mate, bite the bullet - and gopro it too.

 

MPX Test Model

Thanks guys. The boat will fly when it's ready and when the weather co-operates. And it's almost ready......
PS- Gary, there will be a lot of go-pro video after the first couple of tests. I'm going to try to use a carbon tube and extend the camera away from the boat. Another shot will be of the rocker arm that controls the main foil flap. And one aimed at the ama foil.....

 

D4Z experimental calculations/ for the fun of it

I have an F48 RC cat here-about 15 years old. It was designed by me to use a Trapeze Power Ballast System. I've noticed one cat on the German forum using a version of the TNZ pioneered UptiP foils and it foils ,though in the video I saw it didn't seem consistent. So it occurred to me to try to see how big an UptiP foil would be required to fly the D4Z with a 5 knot boat speed/ windspeed takeoff.
The existing trunks might have to be changed but they take a foil with a 2" chord. And the windward foil would almost always be retracted.
So I came up with a foil of 31.5sq.in. total area of one side. The calculations assumed that the cat and the F3 both sailed at a 7.5lb weight.
What is interesting is that the Bradfield system I used on the F3 had a total area of one side of the lifting foils of 34 sq.in.. Area of one side of the immersed portion of each daggerboard on the F3 added another 9 sq.in. which means that theoretically the UptiP foils would have about 26% less wetted surface than the Bradfield T-foil system! Just amazing.
That just convinces me more than ever of the probable value of well designed UptiP foils as compared to a wand based T-foil system.
Very interesting.....

The D4Z with Trapeze Power Ballast System(a minimum of 50% more righting moment than any RC cat w/o such a system) :
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MPX Test Model

Over the last week, as the weather permitted, I wet sanded all the foils and they turned out really slick. That encouraged me to wet sand, fill ,paint the bottom again to get it as good as humanly possible. That job is about half done but it will be finished tomorrow weather permitting.
I used a super slick paint back in the 60s when I was racing Windmills-I won the Southestern Districts with a large lead in 4 of 5 races. Of course it wasn't all the paint -my brother used the same stuff and wound up third! The paint was called Super Glide and was made with molybdenumdisulfide powder in it and had a sort of dark gray color. Can't find it anymore though there is one paint thats close.
I found the powder at Amazon and I'm going to try an experiment: I'm going to spray a small model with clear Krylon and then try sprinkling the powder on the fresh paint. I may try mixing it with clear laquer as well. If either of these work I'm going to use it on the boat.
Either way, this bottom will be very slick the next time it gets wet!
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Pictures-Right picture-just after the mods-the other two today. If the paint works the color will change to a dark gray.

 

MPX Test Model

Main hull sanding mostly finished and final or nearly final paint applied.
If my experiment works(last post) It will be coated one last time and either way it goes the bottom will be wet sanded one last time. Bottom getting pretty slick....

 

MPX Test Model-----Knockdown pressure

Trying to get as much comparative data as I can and this will be added to the Spec Sheet. Many who frequent here will know that I designed and built the F3 trimaran foiler about 15 years ago. It was very successful and never was knocked down during two years of two boat testing in winds up to 20 knots. Reefable rig. The two test boats never pitchpoled either.
So here is some comparative data between the F3 and MPX Test Model:
1) F3/reefable rig
a. Knockdown pressure with the full rig: .39lb/sq.ft
b. Total ama buoyancy compared with max displacement: 75%
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2) MPX Test Model/reefable rig
a. Knockdown pressure with:
----Code Zero: .375lb/sq.ft
----Main + Jib: .41 Lb/sq.ft.
b. Total ama+curved piece buoyancy compared with max displacement: 54%
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This means the knockdown pressure between the two boats is about the same even though the relative buoyancy of the MPX ama+curved piece is significantly lower than the ama buoyancy of the F3 as a percentage of total displacement. Thats because the relative beam of the MPX is greater than that of the F3. So the gust reaction of the MPX won't be much different than the gust reaction of the F3-and thats good to know.

 

More Mini40s

More news from Australia for you
We had more boats on the water this weekend. The link to the video is here.

https://www.youtube.com/watch?v=QrkMwzV_SDo

You will see that we have a number of different foil configurations being tested here. The white boat is my blue one and still has its kinked foils. The repainted Aardvark Shinobi "Bad Habit" has an extension of this concept with vertical foils in an attempt to improve windward performance, and the Nightmare Mk VIII (number 44) has horizontal toes on conventional foils

 

Thanks! You guys should consider trying the Bradfield foil system-it automatically provides all the RM you need. Would be a great test against the surface-percing foilers.

 

MPX Test Model-Moly Experiment

Got the powder in about an hour ago. I tried using the top from a salt shaker to sprinkle the stuff on wet clear acrylic paint and it didn't work. It's too fine and clumps up. Took the top off and spilled a little on the hull. Then I took a brush and brushed the powder down. I was startled by how well it mixed in. I know now that if I mixed it with a clear paint and applied it with a brush it would be likely to work. When the stuff I put on just now is throughly dry it may wet sand out-we'll see.
UPDATE-5/6/14-Not going to work ,at least for now. I'd have to spend close to $35 and take the risk of the laquer reating with the enamel on the boat now. For a future time the laquer mixed with moly is very likely to work and putting the stuff on over duratec would be the way to go.

 

F3 on foils-new information!

Just found out from a guy who sailed one of the production F3's up in Minnesota that they could tack the boat while on foils! For two years we two boat tested the F3's and only did that a couple of times, though we could gybe on foils routinely. This is what he said about the F3:

Having had the opportunity to drive one of Doug's foilers back in early/mid 2000 - but not in quite that much wind, I have yet to see any examples of foilers that "tend" themselves like his on a somewhat automatic basis. Also lake we were on didn't have open water waves, so there might be limitations on waves versus deeper foils.
I would go with the Bradfield wand system as a first step, mainly because I saw the stability in flight and ability to change tacks upwind without dropping off the foils. If you can build a Bradfield system, it will give a lot of instant knowledge without the need to worry about design faults.
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MPX Test Model--milestone!

As of today all construction work is complete-all sanding,painting,gluing etc.! Some assembly, a Dress Rehersal and then we start the final testing under sail.
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looks good - cant wait to see it sailing....

 

MPX Test Model

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Thanks! Me too...Sailing soon.

 

MPX Test Model

This is one of the nit-picking jobs I got to today: applying the red stripes to the foils at the tentative flight waterline. These will give an excellent reference to the actual flight altitude ,especially in pictures and video.
The stripes on the main foil are for an angle of heel of 10 degrees with the main hull about 6" off the water. The stripes on the ama foils are for a nominal flight altitiude of 3" but this will vary with speed.
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