Ac-86 build - Page 4 - RC Groups
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Jul 26, 2013, 06:56 AM
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Quote:
Originally Posted by John Xman
OK need some advice from all builders----

I need to come up with a sanding block that will work for the scale of the male plug. My small 8" long by 3" wide clamp style sanding block is not doing the trick for fairing the 86" length. I am down to 320 grit sanding and having a tough time getting out the 1/100" ripples. Need a flexable sanding block about 18" long?

Any advice would be appricated!

Thanks
John X Man
John,
Check out the following link for a 15" long adjustable sanding block. I know it's a bit pricey but well worth it in my eyes. I used one when I was doing the sanding on an 84" long plug for an AC. Worked very well for me.

http://www.eastwood.com/adjustable-f...r-15-inch.html

Hope that this helps..
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Jul 26, 2013, 10:16 AM
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Dick L.'s Avatar
"Pricey" - Holy Yikes !!!!!!!
Jul 26, 2013, 12:17 PM
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John Xman's Avatar

Ac-86


Sailfish,
I like it, yes a little pricey, but the sanding primer is $60 a pint!
I have gone through 2 of them and its starting to get expensive to get the plug perfect!

I laminated two model grade plywood sections together on 1/8" x 2 1/2" x 24" the other same except 1/16" thick. Added some wood 2x2 by 3 1/2" long blocks at each end about 3" from ends. Then used rubber cement to adhear sand paper.
it works great except I have had to go back to 220 grit. Oh well
Just need to take my time. Part of the issue is the bulkheads at 6" o.c. are now having an effect on the shape. May need to fill the entire inside with expanding foam? (damm bulkhead deflection!)

I found out yesterday that my new job has a model shop and they have a Laser cutter that will do up to 1/8" plywood! This will work perfect for cutting the 124 ribs for the wing mast. Im happy! (most of the ribs will be balsa, plywood is at every 12")

John X
Jul 26, 2013, 03:25 PM
Registered User
John X,
Glad that you have come up with a solution to your problem. I thought that I would post what I had that worked for me. Be interesting to see how your AC does when complete. You have peaked my interest, so shall follow along. Fair winds and following seas..
Aug 08, 2013, 04:54 PM
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John Xman's Avatar

Ac-86


Update: 8-8-2013

Here are a couple of images of the completed 3D model. Final sanding and first coat of gelcoat this weekend- I hope
I will load more images this weekend
Enjoy

John Xman
Aug 09, 2013, 01:40 AM
wolfgang
tuppesw's Avatar
Quote:
Originally Posted by John Xman
Update: 8-8-2013

I will load more images this weekend
Enjoy

John Xman

it's a pleasure!

with a modell in this size you should think about a crew member with a second TX/RX for wing , foils or jib trimming.
Should be easier with two guys in a chase boat.
Last edited by tuppesw; Aug 09, 2013 at 01:56 AM.
Aug 09, 2013, 10:49 AM
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John Xman's Avatar

Ac-86


Tuppesw,
Great idea , double transmitter . Maybe when we have more than my prototype sailing we can come up with some class rules and have it be two transmitters. Foil lifting and cant control along with Wing and jib trim- I like it!

I have been looking for a small used Avon inflatable with a trailer for the case boat and transporting the cat . First I thought a Kayak would work then thought about righting the cat with your rear end below the water line . Besides I want to enter it in the round the island race up in Vancouver BC . and this will require a chase boat.

OK I have more images for everyone . I will also post some images of my sanding block and the male plug this weekend.

Luna Rossa and Artemis will be on TV toninght - Race 3 of LV!

John Xman
Aug 09, 2013, 11:38 AM
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This might end up being the fastest RC Sailboat!!
Aug 14, 2013, 05:14 PM
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John Xman's Avatar

Ac-86


OK a little Update on 3D model-

Added the Jib and Foil lift blocks/lines, etc

Mother in law is staying at the house so I am having tough time getting photos of the Plug and Sanding block Maybe tonight I will hang up the full size drawing of the wing so she will stop refering to the build as "that little boat"

John Xman
Aug 18, 2013, 01:58 PM
Registered User

3D modeling questions


Hello

I have been reading this thread for a little while now and I'm very impressed at the how well you have been building the cat .I have just finished designing a 90cm r/c foiling trimaran. and was wondering about a couple of things.

1. Your 3d models look amazing, how did you create each specific part and put it together in sketch up? I designed the hulls and bulkheads using Orca 3d in Rhinoceros but have not been able to find a way to designs the cross beams ect.

2. What method did you use to make your foils, I have one in mind but was wondering if there are any alternate routes, also is there a ratio of sail area and weight to foil area.

Thanks

Regards
Curtis
Aug 18, 2013, 08:43 PM
Foamy Season is here! MX2#1
pitviper51's Avatar
this is fantastic! I just watched some of the LV cup this evening, these boats are amazing. a bit out of my league as for building one, but I do really want to scratch build a CAT now ...
Aug 18, 2013, 09:49 PM
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John Xman's Avatar

Ac-86


Update-
Male plug is now at the final wet 320-600 sanding stage. Completed fairing and have done last coats with a new HP spray gun that puts down the final primer like glass. Few images of plug below. Will be building the parting board this week!

Madrc570 - the Sketch Up 3D has about 27 components developed so I can edit without screwing up any other surface. Both the foils and the cross beams are extrusions along a curved lines. The key is to weld both the shape the follow line to reduce the number of surface lines. It starts with importing the AutoCAD 2D drawing and tracing the shapes for the elements with arcs and lines. Use the weld command and then extrude along one edge line. worry about locating the element after you create a Component of it. Then rotate and align the Component along a transparent centerline plane.
Be very methodical and plan out each Component. On the wing after extruding the leading edges, I then scale the top to align with the 2D drawing. The key to Sketch Up is Components, Welds and Scale a surface.
You may have to go out on Internet to get the 3rd Party "Weld" application.

My goal is to have the first hulls molded before I head down to San Fran on September 12, to see 2 days of the AC! Lots to do! If everything goes as planned I should have one carbon hull with me on the bleachers on the 14th and 15th! I am thinking of tapping an umbrella to it for some shade?

pitviper51 - Buy two hulls and the cross beams from me and you too could build a 1/10 scale AC Cat!

Custom sanding block shown in last two images- worked great!

John Xman
Aug 18, 2013, 10:56 PM
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John Xman's Avatar

Ac-86


Madrc570,
Few more comments on Sketch Up. The hulls were designed in "Delftship" Navel Architecture software where I designed the shape based on a target displacement of 15 to 16 lbs. and play with VPP! I exported to AutoCAD 3D and then loaded the hulls into Sketch Up. Then I had to clean up the hulls by making the surface edges invisible (over 800 surfaces on the Hulls).

The Wing and the Foils were designed in a program called "Foils" where I could play with NASA airfoils - cord to length ratios and optimize the lift for each. The Wing took months to get right!

The cat was not designed in Sketch Up! Sketch Up was used to get out some 3D images of the cat, but had nothing to do with the design process. I do use Sketch Up to see how the cross beams will connect with the hulls, but this all started with specific programs for the design tasks.

The foils surface area is a calculated for a lift / to speed / angle of attack. I am not giving out that info right now because I want modelers to be blown away when the I post the first videos of the AC-86!

John Xman
Aug 19, 2013, 08:36 AM
Registered User

software


Thanks John for that information, I will have a look at those programs and have a fiddle around in sketch up as well.

Your boat is coming along excellently, I cant wait to see the finished product. I'm starting the bulkhead and hull plug construction next week. I'm just cutting the bulkheads, top and side profiles out of cardboard first to make sure I'm happy with the hulls.


Is there a particular speed or wind speed that you expect your boat to foil at, I'd be interested to see because I'm curious as to whether I'll be able to sail mine in the school pool to test or whether I'll have to risk it being stolen in the ocean (Temporarily living in Mozambique, Africa) I'm Australian though.

Thanks again

Regards
Curtis
Last edited by Madrc570; Aug 19, 2013 at 08:37 AM. Reason: Forgot to say thanks at the end
Aug 19, 2013, 11:32 AM
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John Xman's Avatar

Ac-86


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


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