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

There's nothing from T.S. either on the previous page or in the post #2465 of this thread, Doug... A typo?

 

Tom Speer

Sorry! Post 2460, page 164-----last post on that page.

 

My thoughts;
these complicated unique amas add lots of cost, surface area, complication and weight. They were an interesting experiment back when you started this thread years ago, but when foiling was added their function was all but eliminated. You have the original MPX model to experiment with -you could pull off the lifting foils and see how it behaved and checked the self righting. Now that you are creating a second RC model proto for a real life boat, why not go with cheaper, lighter, conventional floats?

 

WOLF---daughter of fire arrow

What can be done after the planing tests is simply to reduce the expanded aft planing area(cut it off) if there is no other reason to keep it there. Testing the planing area on the Fire Arrow would not be as effective as testing it on WOLF. I have a hunch that that planing area may have more benefits-such as roll damping at slow or no speed-testing full size will prove or disprove that. The other elements of the two stage amas are critical to the overall performance of the boat-like the increased height of the center of buoyancy of the whole TSA(two stage ama) . And the TSA shouldn't be heavier than a conventional ama and probably won't be more expensive. However,regardless, it is far more effective for a small foiler than a conventional ama would be.
The concept model of WOLF is not an rc model-it is being built to show what the fullsize boat will look like.
Thanks for the comments.......

 

Wands / Speer

Slavi, whats your opinion of the two posts Tom wrote?

 

WOLF---daughter of fire arrow

Looks like max beam will be somewhere around 16.5' with the limitation being how the amas will fit when folded-will fold to a max beam of 8'. I have to experiment with it some more but I don't think I can go any wider. That will work-its still slightly oversquare. The more beam the better the mainfoil/ ama foil will work when the main foil develops downforce and the ama foil has an equal and opposite increase in vertical lift. I'll get back on it in the morning and see what I can do. Part of the limit is how high the thing sits on the trailer-right now it would be close to 5' from the bottom of the boat.

1/12/17--UPDATE: I may get almost 18' max beam including the planing surfaces. The amas would fold one on top of the other for a total height of about 5'4" from the bottom of the boat. This will be perfect if it continues to work out. I'll ask my sailmaker to measure his trailer which is identical to the one I'll get.
If the beam was proportionately equal to the Fire Arrow beam it would be 18.48'. It all depends on how it fits the trailer......

1/13/17--UPDATE: Going with 18.3' beam overall. Folded that won't fit in the garage(no vertical clearance) but neither will 16' and I won't go that narrow. So, I talked to Scott (sailmaker) and he said he could make a cover for the folded boat which with the 18'+ beam will be 8' off the ground with the boat folded.

 

WOLF---daughter of fire arrow

Updated specs and notes:

LOA 15.458' (4.7m)
---
Beam max-18.3' (5.58m)
-beam folded-8' (2.4m)
-main hull beam on deck: 2.625'(.8m)
-main hull beam at wl: 2.125'(.65m)
-main hull L/B at wl:7.27/1 (planing)
---
Two Stage Ama-11.3' (3.5m)
-ama hull-7.7' (2.35m)
-ama hull beam .58' (.18m)
-ama hull L/B=13.3/1 (planing)
- curved piece-5.7' (1.74m)
- overlap- 2' (.61m)
- two stage ama canted bottom out 12 degrees.
- two stage ama buoyancy(not including crossarms)=252lb(61%)
---
Weight:
-boat-200lb (91kg)
-crew-215lb (97.7kg)
-sailing/flying weight: 415lb. (188.7kg.)
---
Sail Area:
-main + jib= 160sq.ft(14.9sq.m)
- spin/screecher about 150 sq.ft(13.9sq.m)
-pounds per sq.ft./SA:
--upwind=2.59
--downwind=1.34
---
Designed flight angle of heel: 5.5 degrees to 15 degrees. Standard 10 degrees.
---
Main hull flight altitude at centerline: .5'(.15m)---2'(.61m),Standard 1.19'(.36m)
---
Righting moment:
-crew 215 @11'= 2365ft.lb.(3206.5 N/m)*
-boat 200 @ 7.5'=1500ft.lb.(2033.7 N/m)
TOTAL RM= 3865ft.lb (5240.2 N/m)
Downforce from main foil(if used) approx. 1500ft.lb.(2033.7 N/m)
* N/m conversion done from online converter
---
Foils:
-uptip foil in each ama, adjustable AOI and up/down(mostly retractable). tentative AOI-3-5 degrees over twisted foil.
-mainfoil wand altitude control, adjustable AOI(nominal 2.5 degrees),up/down(mostly retractable).
-rudder T-foil, adjustable AOI(nominal zero degrees).
---
Planing surface on lee ama hull is designed to be flat when main hull is just clear of the water(6") and that will occur at an angle of heel of 12 degrees.

-------------

 

WOLF---daughter of fire arrow

The folding system on this boat will make set up extremely fast since it is only a matter of sliding the inner tube and releasing a latch on each crossarm and then fold. Eric Sponberg helped with the original work on the slide system and came up with the latch on the bottom of the tube. The hinges are glassed and carbonated to the two tubes so that the carbon doesn't touch the SS hinge.
The new tubes will likely be smaller than those shown in the illustration-probably 3"-3.5" OD carbon. And the push-pull rod will go toward the center of the boat. The ama cant angle and position and type of foil are also different on WOLF.

 

WOLF---daughter of fire arrow / Ama cant angle

The amas on this boat are at a cant angle of 12 degrees and when the boat is loaded and level they are 6"(152mm) above the waterline at the aftmost centerline of the ama hull.
The ama hull is planing and the aft planing surface is parallel with the water when the boat is at an angle of heel of 12 degrees(off the foils)-and the main hull is just above the water.
--
The nominal flying altitude of the main hull on foils is a little over one foot(304mm) at an angle of heel of 10 degrees. At the same flight altitude and angle the ama is 9"( 228mm) above water. The flight altitude and angle of heel are completely adjustable. At 10 degrees the windward ama foil is well clear of the water(and most waves). And that is a big deal when sailing the boat because it means that the foils don't have to be adjusted up and down with every tack/gybe making it much less labor intensive to sail.

 

Fire Arrow Test Model Testing and Development / WOLF

So far in the limited model testing I'm convinced that the dual wand* controlled main foil works best because it's 100% automatic and requires no crew attention. However, the placement of the wand and a single wand system like the Whisper and F101 is going to be considered.
In the last test of the model, the foil system ,including the wand controlled main foil, worked 100% perfectly in light air foiling.
* one midship wand on each side of main hull-windward wand clears the water when flying.
There are other types of main foil that might be worth experimenting with on the Test Model or the 14 footer if it is built:
1) Surface Piercing T-foil--Advantage-no moving parts; low drag when racing. Disadvantage-no automatic downforce for gust response and/or more power in stronger wind. Increase in drag as outboard tips breach the surface.
Possible loss of automatic pitch control with no facility for downforce.
Highly experimental version could have upside down asymmetrical section for automatic downforce when boat pitches down.
--
2) Manual mainfoil flap control--Advantage-less drag when racing; full control of mainfoil and flight altitude including downforce. Disadvantage-requires constant attention. This could be done in such a way as to allow wand control or manual control on demand-in other words the control system could be switched between manual and wand control with a retractable wand.




This jump wasn't intentional but happened on the second day of testing where the boat was overpowered and sailed with too much rudder throw and wands that were too long. Those elements combined to throw this 21.3 lb Test Model completely clear of the water!

 

Howdy Doug,
I'm new to the forum but I have scanned the majority of this topic - all 50 pages (at 50 posts per page). You've had quite a ride over the last few years. I have a question for you. Back in post 1302, you referenced a German built autonomous surface piercing Tri and added a couple of pictures. You indicate it's on the German equivalent forum to this - can you post a link to this site? My history is the design and build of very high aspect ratio sailplane wings and structures and I'd like to combine some of the attributes you have presented in this thread with a wing structure and am looking for inspiration and best practices.
Many thanks. Tony

 

Wing

Hi, Tony and welcome to the forum! If you have any questions at all don't hesitate to ask....
I have no idea where that picture came from and couldn't find the post about the German forum .
Here's a link to an 86" wingsailed cat-still being built- on rcgroups. If I remember right the guy has some detail on the wing but you'll have to search the thread.
https://www.rcgroups.com/forums/showthread.php?1887900-Ac-86-build

Link to the German forum: http://www.rc-network.de/forum/forumdisplay.php/166-Mini-40

 

Doug, if you hadn't seen this.
At 8 knots wind and 15 knots speed.
A Mini650 - 21 feet - impressive.
https://www.facebook.com/SEAir.gravity/?fref=ts

 

Thanks, Tom. I posted a couple of things about it in the "New Monohull Foilers" thread under "Sailboats". Surely is very cool! I still remember the bad old days on certain forums where I was lambasted for suggesting a monohull keelboat could foil! Thank you, Hugh Welbourn!
It's hard these days to keep up with all the foiling development-just incredible!
Seems almost like if it sails it can foil......

http://www.boatdesign.net/forums/sailboats/new-monohull-foilers-2016-a-54975-3.html post 39 and others

 

WOLF---daughter of fire arrow / Concept Model

Here are a couple of shots that show the dihedral of the crossarms: (see post 2482 above and the top of the next page))