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

MPX Test Model

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Welcome to the forum and to this thread! Thats a good idea-thanks. I'm going to test sail it before too long but if I have trouble I will do what you suggest or tow it behind an outboard.
I have access to three video cameras(one of which is a go pro) and hope to have video of the first sail and every one after that. And it looks like I will have help that first day so I don't have to sail and take video at the same time.
The main wand controlled foil is completely adjustable as are the two ama foils. One of the things that will become apparent pretty quickly is how well the experimental ama foils work-going to be real interesting. The TNZ type foil is designed to provide vertical lift and lateral resistance at the same time. The MPX version of that foil(see picture below) will not be the sole source of lateral resistance on this boat so it's going to be interesting how well it functions-I expect(hope) it works well-we'll see. But the problem with towing the model is that there is no requirement for lateral resistance so the "leeway coupling" that may exist(and/or be required) to some degree won't be present.
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PS-Navygate, how much do those winches cost?

Pictures, L to R : 1) first rig fitting-this showed up problems with the jib and main clew that have been rectified, 2)-3) Final float test and first float test with the 5.5" main hull extention and added buoyancy-noticeably less drag in pulling or pushing, 4) MPX ama foil inspired by TNZ but different in that it should not require more than one angle of incidence adjustment thruout the speed range.

 

At that scale would a rod and reel not serve as well after calibrating the speed of the wind?

 

MPX Test Model

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Since I (almost)never fish I don't know how fast you can reel in? It would have to be -at a very minimum- 7.3 ft./sec.-is that realistic? 7.3ft/sec=5mph(4.35 knots)= minimum takeoff speed.

I found this RC Glider launching winch-$850: http://www.irfmachineworks.com/lbwinch/lbworderinfo.html

 

High expense unnecessary, Doug, just simple rod and reel, secondhand, maybe 5 dollars; here's Jim Young's power foiler model he did a decade or more ago - you get the idea, although print quality is down, has been copied too many times

 

MPX Test Model

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Thanks Gary. I guess I don't see how any rod and reel that I've had very,very limited experience with would pull this boat at takeoff of speed: 7.3 ft. sec..
Consider a 4" diameter reel: it would have to be turned at 7 revolutions per second--and thats 420 RPM! A 6" reel would still require 4.7 revs per second. Unless you have some special reel in mind I don't see it working at all.
I certainly would not pay $830 for a winch-or even a tenth of that!

 

An open spinning reel with a wire bail will pull the line faster than a fly reel.

 

MPX Test Model

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Thanks Hoyt-any idea of actual speed OR reel diameter?

 

MPX Test Model

Heres a link to the MPX on a German RC forum: http://www.rc-network.de/forum/showthread.php/431908-MPX-Fire-Arrow-RC-Trimaran-Scale-Test-Model
Lots of interesting stuff on this moderated multihull forum!

 

Thank you.

You are most welcome, my pleasure.

Costs can vary widely. You could certainly improvise though.

 

No but I am sure it is faster than your requirements. You would need to time it with a stopwatch across a marked course.

 

Bridle to amas off center with rudder trim to go straight, try for 3 to 5 degrees for leeway. Hook to fishing scale behind outboard for drag numbers?

 

MPX Test Model

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Thanks, Jim. I don't expect to have to pull it to test the foils ,but you never know. If I did, it's pretty important that the boat is pulled from a mast stump with the line attached at the vertical position of the center of effort.That assures that the pitching moment of the rig is accounted for in the tow test. The rc gear would have to be aboard for steering. It would probably be possible to "crab" the boat using the rudder but that would have to be done very carefully. If the ama dug in at a sideways angle the rudder might become ineffective and all hell could break loose with the operative word being "break".
I was really lucky when I first launched the F3 years ago. Most people including Dr. Sam thought I should tow it first like I described above, but I decided to put it in the water and sail it. I had built two of the boats and took the red one down to the pond with a friend on the camera. It was very light air-the Davis wind meter said between 4-5 mph. The thing foiled right off the bat! The only thing that had to be fixed were the wands-they were round and vibrated very loudly with a buzzing sound. So they were squared off and worked fine.
The "moral" of this story is that the F3 went right from the building board to foiling 13 years ago and though it is much more complex in some ways I want to see if this boat will work right the first time! If it doesn't I will fix the problem(s),but I sorta think it will.

 

MPX Test Model

I found this(for the first time in my lifetime) on another thread and it was so moving to me I had to post it here-it's relevance to me and to this thread cannot be overstated. My Dad and Mom and another good friend have said as much to me at various times-words to live by:

Kipling's IF...

If you can keep your head when all about you
Are losing theirs and blaming it on you,
If you can trust yourself when all men doubt you,
But make allowance for their doubting too;

If you can wait and not be tired by waiting,
Or being lied about, don’t deal in lies,
Or being hated, don’t give way to hating,
And yet don’t look too good, nor talk too wise:

If you can dream—and not make dreams your master;
If you can think—and not make thoughts your aim;
If you can meet with Triumph and Disaster
And treat those two impostors just the same;

If you can bear to hear the truth you’ve spoken
Twisted by knaves to make a trap for fools,
Or watch the things you gave your life to, broken,
And stoop and build ’em up with worn-out tools:

If you can make one heap of all your winnings
And risk it on one turn of pitch-and-toss,
And lose, and start again at your beginnings
And never breathe a word about your loss;

If you can force your heart and nerve and sinew
To serve your turn long after they are gone,
And so hold on when there is nothing in you
Except the Will which says to them: ‘Hold on!’

If you can talk with crowds and keep your virtue,
Or walk with Kings—nor lose the common touch,
If neither foes nor loving friends can hurt you,
If all men count with you, but none too much;

If you can fill the unforgiving minute
With sixty seconds’ worth of distance run,
Yours is the Earth and everything that’s in it,
And—which is more—you’ll be a Man, my son.

 

MPX Test Model

Comparison of "old" main hull to new. 5" added length, 3.5lb added buoyancy and 1 lb added weight. L/B ratio increased from 5.7 to 6.2/1:

 

MPX Test Model

Here is a shot of the stern deck "decorated":