Ac-86 build - Page 5 - RC Groups
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Aug 19, 2013, 12:29 PM
Thomas Armstrong
Quote:
Originally Posted by John Xman
Madrc570,
Foils will be a laminated on a curved wood mold block with 6 layers of 1/32" plywood with carbon scrim between each layer, about 1/4" cord width. The (sanding) shapping of the foils will be critical!
That's an interesting idea! Wonder if it will hold the loads... Will you also laminate the whole thing with CF after sandong?
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Aug 19, 2013, 12:43 PM
Registered User

Continuing with sketch up


Also John

I'm not sure why but when I imported my hulls into sketch up and measured them it said they were 2.2m rather than 90cm, don't know why this happened because they were scaled correctly in Rhinoceros .

Attached is a couple of pictures of the boat minus sails and foils, not sure how to make my foils in sketch up as I tried a couple of programs and wasn't able to get the physical size correct for the boat, ie the foils were bigger than the boat itself but yeah Thanks very much for your advice on the subject I thoroughly appreciate it.

Kind regards

Curtis
Aug 19, 2013, 01:37 PM
Registered User

Boat details/ Dimensions


Quote:
Originally Posted by John Xman
Madrc570,
Post some images of your build. What is the length and beam?
If it is a Cat or a Tri remember a single hull needs to handle the entire displacement, don't make the mistake so many make in volume of hulls needed for single in water hull.

The AC-86 should lift out of the water at about 15 to 18 MPH! The windspeed would be in the range of 10 to 12 MPH. Top end from VVP is over 25 MPH! This is very dependant on the shape and size of the build foils. I have designed the foils to drop out the bottom and be easily swaped out at the sailing site so I can try different foils.
Foils will be a laminated on a curved wood mold block with 6 layers of 1/32" plywood with carbon scrim between each layer, about 1/4" cord width. The (sanding) shapping of the foils will be critical!
John Xman
Hi John

As this is a school project and teachers can be picky and also I don't really want my ideas sold to the world. but here are some basic details . Length 90cm beam 110cm mast height 1.4m. 6 foils in total all T foils, Rudder ,centreboard 2 on each float hull.

You can sort of get an idea from the renderings I posted a couple of hours ago. but yeah if you want some more info I'd prefer to do it by email if you don't mind.


Thanks for all your help

Regards
Curtis
Last edited by Madrc570; Aug 20, 2013 at 07:21 AM. Reason: email wrong
Aug 19, 2013, 04:28 PM
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John Xman's Avatar

Ac-86


tarmstro,
Yes - the foils will get an outer laminate. After shaping the (wood) foils are wrapped in two layers of 5.8 OZ uni-directional carbon and back into the shape blocks with the addition of rubber pads for a final cure with preasure (blead out extra resin), then trim, paint and final wet sanding for fit. This will produce a\a very strong and stiff centerboard/foil. All of this will be shown here for your viewing pleasue-

John Xman
Aug 19, 2013, 04:49 PM
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John Xman's Avatar

Ac-86


Madrc570,
When you inport into Sketch Up you will have to rescale the item almost every time. Not sure why? but grab all the surfaces for the center hull and right click and make it a Component. Then you can select it and use the scale command to control its size in three directions. Be sure to grab the right grip to scale it proportionally in all directions. Good luck

For the foils start by drawing an airfoil in plan. Make sure it is a surface. Then from the trailing edge draw lines / archs vertically to define the path for the airfoil to extrude along. Select the lines and use the "follow Along" comand to extrude along the path of the lines.
Aug 20, 2013, 06:59 AM
Registered User

Sketch up and other


Thanks very much John for your help again

I will do, and now I'll be able to show my friends and family what the heck this 'some sort of boat' is!!

I starting the card mock up today as a final check before build initiation I will post some pics of it later on.

Good luck with your build, the hulls look great.

Thanks
-Curtis
Aug 20, 2013, 10:43 AM
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DLord's Avatar

Super Cat


John, very interesting project! Looking forward to following your progress.
I'm building a large foiling tri 5'LOA, 7' Beam, 29 sq.ft(4200sq.") light air SA, rotating wing mast(not a wing rig).
Please check it out here when you can: http://www.boatdesign.net/forums/mul...tml#post646685
------
I'd be glad to try to help you in any way I can with your foil system.
PS-thanks to Curtis for the letting me know about this project!
Aug 20, 2013, 10:57 AM
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DLord's Avatar
Here are some pix of my ama foils-the main hull foils are like the F3 but with dual wands: this boat will sail with the two foils on the main hull and one ama foil in the water; the other not used.
The last three are a "study" illustrating how the configuration changes with retraction, though initially the ama foils will not be retractable but only one will be in the water at a time.
Aug 20, 2013, 11:28 AM
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Foils


This may be simpler, mine should be delivered next week for my foils.

https://www.flyingfoam.com/
Aug 20, 2013, 11:48 AM
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John Xman's Avatar

Ac-86


Doug,
I true pleasure to have you as a resource for the foils. You are a legend in RC! I will send you my personal email- Big thanks! You foiler project looks amazing!

The AC-45 cat has the same lifting system as the AC-86. The main difference is inside the foil box the foil is in a canting box with rollers. This box will allow the foil angle of attack to be controled by a servo. This is the forward control rods in the 3D images.

I am working on a 3D cutaway of the system. will post the images soon!

John Xman
Aug 20, 2013, 12:54 PM
Registered User
Quote:
Originally Posted by DLord
PS-thanks to Curtis for the letting me know about this project!
No worries Doug!
Aug 20, 2013, 07:37 PM
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DLord's Avatar
John, these are two of the original hand drawn building instructions of the F3 foil system. I can't find any of the finished work-maybe it will help. The wand is designed to be approx. 45 degrees when the flap is neutral. The system had 20 degrees flap up and 30 degrees flap down. The long part of the rockerarm attaches to a spring that pulls the wand against the water so that it responds to altitude changes.
On the F3 system, the boat used dual independent wands which allowed the foils to develop all the RM for the boat. Thats why the boat is oversquare-the further apart the main foils are the less force is required from them and the lower the resultant drag. The mainfoil on the F3 and on the new boat is designed to support 80% of the load and the rudder 20% at takeoff-after takeoff, as speed builds the rudder foil will automatically unload then start to develop downforce. The main foil is set at +2.5 degrees referenced to the static waterline and the rudder zero degrees to the same reference.
That may be an important consideration on a cat because you can't get the foils as far apart as on an oversquare tri. Frankly, if I were you I'd stick with the brilliant Team New Zealand 3 foil configuration with the windward main foil retracted. You can still use a wand(which would be a good idea) if you do it so that the wand is attached directly to the foil and retracts when the foil does.
I don't think you'll need an adjustable angle of incidence rudder foil when you're sailing if you use a wand on the main foil-but you could experiment with it. I used it on one of the F3's and it didn't help in any way and was not necessarry.....
Last edited by DLord; Aug 20, 2013 at 08:00 PM.
Aug 20, 2013, 07:43 PM
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DLord's Avatar
And this is some of the dual wand(NOT independent) detail on my new MPX Test model-it has a wand controlled main foil that works in conjunction with a single ama foil and the rudder foil.
Pictures- L-R-1) The plate that supports the wand axle can slide slightly fore and aft to change the angle of incidence of the main foil which is attached at point "A". Point "B" is where the pushrod from the main foil flap is attached. Point "C" is where a line to the tension spring is attached-this spring holds the wand against the water so it can provide altitude feedback.Points "B-C" are on the rocker arm that transmits wand altitude feedback to the mainfoil flap so that the preset altitude(+angle of heel on this boat) is maintained. Point "D" shows the rotating axle to which the dual wands are attached., 2)-3) show different views of the wand system., 4) the part of the wand to the left is the "paddle" whose concept was invented by Dr. Sam Bradfield-the idea being to smooth out wand input by allowing the wand a degree of planing.The MPX paddles are made of thin carbon that can flex under load. Paddles of different shapes and sizes are common on Moth foilers. On the F3, when it was first launched we heard this very loud buzzing sound from over 50' away: turns out it was the dual independent mainfoil wands. They were circular and as soon as they were squared off the noise and high frequency vibration stopped. These first MPX wands are set for a main hull altitude of about 6" corresponding to an angle of heel of about 10.75 degrees. They are not yet adjustable but will be for an 8-12" altitude(angle of heel up to 17-20 degrees for testing) or they can be disconnected to allow manual control.
Last edited by DLord; Aug 20, 2013 at 08:00 PM.
Aug 21, 2013, 03:49 PM
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John Xman's Avatar

Ac-86


Dlord,
I will have adjustable rudder post for fore aft angle (2.5 degrees) but the rudders will not be adjustable during sailing. Basically you will need to bring the cat into dock and adjust angle then head out again.

I really like the idea of the main foils/centerboards being adjusted automatically with a wand system. This would eliminate one servo and the skipper trying to control the lift (foil angle) from shore. In place of the rods from the servo I could mount a wand from the centeboard trunk (Outside box) that directly is linked to the Inner canting foil box.

There are two foil boxes. The Outside box created the opening in the hull and has one thru bolt for the Inner foil box pivot about 1/2" above bottom of the hull.
The Inner foil box has four rollers for foil vertical movement and the blocks to lift the foil from the center Pod winch. The outer foil box will be molded in Carbon fiber and the Inner will be made from double aluminum plates.

Thanks DLord you are the man!

The images I have attached are the current design, but I am going to redesign for a Wand System. So don't go nuts commenting on something that will change.

John X Man
Aug 21, 2013, 04:50 PM
Registered User
DLord's Avatar

Super Cat


John, your renderings are outstanding! Here are some shots of the Bradfield Osprey foil system: the foils are retractable and the wand mounted directly to the foil. On your boat will you keep the "L" foils or go to a "T" if you use a wand?
Have you got any thoughts about how to do(control) a flap on the "L"?
The yellow hull shows Bradfields Rave that used a system like the Osprey-wand mounted directly to foil.
For what it's worth, I included a rough sketch by Magnus Clarke(Canadian C Class Team) of his idea for a flap on a curved foil.
Good Luck! Doug


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