Small Tri Test Platform

Discussion in 'Multihulls' started by P Flados, Sep 30, 2014.

  1. P Flados
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    P Flados Senior Member

    Starboard foil mod in progress. Here is the cross beam, amas and foils pre-mod.
     

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  2. P Flados
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    P Flados Senior Member

    Here are some photos of the in progress mod
     

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  3. Doug Lord
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    Doug Lord Flight Ready

    Looks good, Paul! Are you relying on the ama foils for lateral resistance as well as vertical lift?
     
  4. P Flados
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    P Flados Senior Member

    The lateral resistance force is an issue I have thought about a lot.

    The angle portions of the ama foils are asymmetric and have some 'toe in".

    In reaching foil assist mode, 80% of the lee foil angle section will be submerged and should do fine for lateral resistance.

    This mode may eventually result in a full fly, only 1 foil + rudder T foil wet, up-tip stable config. This would probably need to have more heel than desired (hurting lateral resistance) to keep enough foil in the water with the main hull just clear. I can shim under the foil pivot to offset heel if needed. I can also add some very small turn down extensions to the foils (this would get me into a weird Z foil).

    For upwind brisk conditions, I think I should rotate the upwind foil out of the water and see if the lee foil works well solo in foil assist mode. I really do not think I could ever get good upwind VMG full foiling with this boat.

    For light upwind, I have an easy secret weapon. Both amas foils can be rotated up out of the water and my combination paddle - lee board (currently just a rectangular planform NACA 0012, but adjusted for a nice high aspect ratio and good planform) set up for lateral resistance.

    For more downwind, I am not sure what will work best. I have plenty of options to try.

    Project updates:

    I did order a used Etrex Vista GPS off of E-bay for under $40. Should help me evaluate what it really happening. I think can set to display heading, current speed, vmg and peak speed all at the same time.

    I also worked out adjustable stops for my rudder and port ama foil. Starboard foil adjustable stop will come after the foil mod is finished.

    The Starboard foil mod is more than half way. Most of the structural carbon addition is done. The bottom was done night before last and a bunch of carbon tow added added to the top (main portion and joint) yesterday. A little more carbon was added today to the top side of the extension to stiffen the tab (fixed flap) on the trailing edge and some other misc areas.

    I am also toying with the ability to change the cross beam mount to include a pivot and provisions for adjusting ama foil AOA while out on the water. Possible options include a rotating adjustment knob, a manual operating hand lever, a foot pedal, a linkage to a central feeler out front, or planing ama floats mounted to act as feelers (credit to the Ketterman brothers for inspiring the last 2).
     
  5. P Flados
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    P Flados Senior Member

    Starboard foil with extension is ready for testing. The extension "Up Tip" angle is a little less than I was trying to get, but this and other side to side differences may actually yield interesting comparison data.

    Tomorrows forecast for wind (just over 10 mph) is Ok but little lower than I want for this boat.

    The GPS I ordered will not be here until next week and I will not be sailing next weekend. Good sailing conditions may get less likely quick. I am hoping to get some good data before it gets too cold. Last year I did some sailing when the air was decent but the water was cold. Since the testing I want to complete may be pushing the envelope of boat structural abilities, I will probably need to be more cautious this year.

    I also did a "quick fix" to allow of rotation (should be about ± 4°) of the cross beam using the 4 wingnuts that secure the two brackets. This can be done on the water, but not while sailing. This will allow me to try adjusting foil AOA between runs.

    I can also slide the beam side to side. All along I had planned for this. With a longer beam to Lee, I can increase effective beam by 3 - 4 feet when I am sailing with only the Lee foil down.
     

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  6. P Flados
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    P Flados Senior Member

    Got in some sailing today.

    Did not break anything for a change.

    Tried alternating between one and two ama foils down. The two foils down mode seems faster.

    The ama foils generate a lot of roll stability. When the sail is loaded and the boat moving, it will sail with no heel and crew withing 6" of center line.
     
  7. rcnesneg
    Joined: Sep 2013
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    rcnesneg Senior Member

    Videos and pictures of it sailing please!
     
  8. P Flados
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    P Flados Senior Member

    Videos are not likely soon. I sail solo and the only video devices I have are the non-water resistant phone my employer provides me and my wife's non-water resistant camera.

    Also, I am betting actual performance is not really worthy of videos at this point.

    Right now, I need to focus on a steady progression of things I want to try. At some point, I should probably put some effort into getting some on the water video. We will see.
     
  9. Doug Lord
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    Doug Lord Flight Ready

    Tri Test Platform

    Thanks for keeping us informed, Paul-this will be a great thread! If and when you want video there are very inexpensive video cameras available-like between 30-$70. Used on model aircraft and sailboats among other apps.

    Here's is an example of a small cheap video camera-there are many more in this price range: http://www.nitroplanes.com/86p-988-dice-minicam.html
     
  10. P Flados
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    P Flados Senior Member

    Yesterday I did a re-work of the cross beam mount to allow better ama foil AOA adjustments. I now have a range of adjustment that goes from 0° AOA (left photo) to 15° AOA (right photo) for the ama foil horizontal sections.

    Today I took the boat out. Initial wind condition was too strong for my comfort zone and at a not so good angle. It took more than a few runs to start getting settings dialed in.

    Wind started to let up about the time I started to feel in control and smooth with some fast reaching back and forth (actually "upwind" some as there was a strong cross tide) in foil assist mode.

    The tide was also in the same general direction as the wind, so apparent wind speed over water dropped the more I headed down wind. Got one broad reach in with enough wind such that I was able to confirm that the boat was willing to full foil (or close to it). I did not get full foiling due to excessive AOA (rise up too fast, ventilate & crash back down a couple of times).

    My AOA adjustment mechanism worked ok but it required 2 hands to adjust and was not quick and easy. I will re-work it before next time out.

    I started to work upwind to allow some more broad reaching, and by the time that I was ready for good run, the wind slacked off too much for any more fast runs.

    I also goofed up & left my GPS at the house. No real data to share yet.
     

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  11. P Flados
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    P Flados Senior Member

    Call me a glutton for punishment.

    Saturday, there was not much wind. I kept debating a sail. The Windfinder forecast said that there would be good wind at 5:00 pm. Eventually I decided to go to the large pond at a park in my neighborhood.

    I packed up and got there at 3:00 pm to setup. It was just dripping when I left the house, but became a steady light rain while I was setting up. The temperature dropped from 55 °F to 50 °F while I was there.

    I had hoped that the wind would increase from around 4:00 pm until the forcast strong winds at 5:00 pm. Instead, it went practically calm from 3:30 to 4:30. At 4:30, I was starting to shiver and the wind was still just a few puffs that I could not seem to catch.

    From 4:45 to 5:00, it was still calm 50% of the time and puffs of sailable but shifty wind in between. I was getting in a couple of runs fast enough to try to get the foil AOA dialed in. However, I was also starting to get too cold (hands starting to get clumsy). I decided to pack it in. As I was packing up the boat, the winds became much stronger and steadier of course.

    In addition to trying to get foil AOA dialed in, I was trying out a couple of gadgets. I now have a handheld Garmin that would have been nice for monitoring speeds while sailing. My not so new NiMiHi rechargeble AAs dropped to below required voltage before I really got to use the device.

    I also recently upgraded my cell phone to a cheap water resistant smart phone. I loaded an app (Move! Bike Computer) that would display speed and would record tracks. The speed display gave me trouble due to the rain. However, it did record the track.

    Using the track was a real pain. I tried all kind of free software to evaluate it. I eventually figured out the following sequence:

    • Export using the GPX file format
    • Open it in GPX Editor, edit it and then save it
    • Evaluate it in GPS Action Replay 3.3.3.
    Peak speed was 9 kts on a downwind run.

    Sunday, the rain was gone, the wind howling and only 50 °F. After I while I decided to go back out. I went out and set up in the cold strong/gusty wind. It was enough to cause some whitcaps on the pond. The launch corner was dead downwind. I got on the water and started working my way upwind. This boat is not great upwind. When making decent headway, the angle between tacks is probably ony 50° (kind of hard to tell on the pond as the wind direction shifts adjacent to each side due the ground slope and tree line).

    As soon as I got halfway up the pond the wind started to die off.

    For the entire sail after the first two tacks, it was mostly calm or light with a occasional puffs of decent wind. With it dry and sunny, I did not get a chill and was able to stay out longer. Peak speed was 9.8 kts on a reach (very close to 90° to true wind direction).

    The boat is definitely not "dialed in" and I have a lot to learn for getting the most out of this thing. Occasionally I hit a sweet spot and it just glides forward at good speed with low pressure on the rig. Other times, the rig has plenty of pressure, but the boat feels very draggy.

    With the undersized rig, I understand the need for strong winds to get the speeds I want. I guess I just need to be patient, and keep trying.
     
  12. Doug Lord
    Joined: May 2009
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    Doug Lord Flight Ready

    Congrads on keeping at it. 9+ seems pretty good-how are the foils behaving at that speed? Is the main hull close to coming loose?
     
  13. P Flados
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    P Flados Senior Member

    Thanks Doug.

    I am coming to the conclusion that my foils really do not extend far enough down into the water. It is probably capable of full foiling, but only if everything is perfect. I have had some ventilation issues when the horizontal sections get too close to the surface.

    Until I can decide on an upgrade that I want to do, just sailing this configuration to explore the limits is a worthy effort. I am pretty sure I can push it a lot faster if I can dial it in a little better.

    Although the wind is messy, the pond sailing I did this weekend gives me very flat water to sail on. Flat water really helps my prospects at getting lucky with some kind of full foiling with this version.

    Also, it is a great feeling to be zipping along at a good pace, get hit with a gust and have the "foil assist" kick in and keep the nose up. Foil assist it the only thing that has kept me from countless nose stuff events.

    The RM from the foils is also great. Even when pushing hard, by just sitting from 0" to 18" off of centerline, I have my choice. I can keep the boat vertical, lee ama skimming, or windward ama skimming. It also kind of "locks in" to a mast angle and tends to stay put with minimal effort on my part.

    FYI, you were worried about bad altitude data from you GPS. I am getting altitude numbers that are bouncing all around. This is what I call a high "noise to signal" ratio. I think it is safe to just ignore goofy altitude data from your GPS tracker.

    Also, what software were you using to evaluate speed data.
     
  14. Doug Lord
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    Doug Lord Flight Ready

    Paul, I'm using the software that came with the tracker "@tripPC".
    Next time we sail, I'm going to put my Velocitek speed puck on the boat and compare it to the iGOTU tracker's results. Then I may feel better about relying on it. The speed puck says my car is 5-9mph slower than the speedometer says it is. I know car speedo's are sometimes set a little slow but this seems ridiculous.
    Keep testing and good luck!
     

  15. P Flados
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    P Flados Senior Member

    Doug,

    Car speedos are set high by the makers on purpose. They do not want customers blaming them for speeding tickets.

    I have way more confidence in GPS based speed.

    I have compared several automotive GPS speed indications to the old standard, 1 minute per mile marker while going 60 mph. I have never found one the did not match up to within my start/finish uncertainty.

    For what we want, I consider a speed track evaluated with software intended for giving accurate speeds to be as good gold. However, some of the stuff I tried only showed speed changes in coarse (1.9 kts) increments. What I ended up with was recommended on a speed sailing (kite or windsurfer) site.
     
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