RG65 Cobra5 Patterns

What material did you use for the panels? Soft or hard balsa? thin ply? I would probably go with 6x36 (1/16" hard or 1/8" soft) balsa sheets, because some 1/32 ply would cost about $120 at the LHS. Did you pre-bend?

féfé minitux minituxII palo de agua seabug simplet and tinker are made from flat panel

you can find all this plan in my website http://rg65.free.fr

@ntoine

Thanks, Antoine, for keeping your website up to date. It really is a great source of plans.
You may want to include another, based on a vintage Marblehead design, the Riptide: http://www.rcgroups.com/forums/showthread.php?t=1175771 I’ve just finished one and am waiting for its maiden voyage. However, Claudio’s Delta rig doesn’t add to its vintage looks.:slight_smile:

@ martinan everybody to add plan to the database ( who want to be international and not only french) just send me the files @ rg65@free.fr
be care ony the designer can send the plan and an autorisation to put it on the rg65 design database

@ntoine

I used the Scharming MK8 in this years nationals with good luck and it is a hard chine boat. I only have the frames as a DXF. PM me if interested. Overall I really liked the design. planning on building a cobra for comparison this winter. I also have a blue streak to compare to as well.

Tom, Craig Huzway is experimenting with a vac-formed plastic hull. It’s a round version of the Ranger that I sailed as a hard-chine boat in Albuquerque. He used his CNC machine to cut the plug from the Freeship files I sent him, then sanded an primed it. He has pulled a couple of hulls on his vac-form machine and they look promising…a bit heavier than my balsa, but more substantial for the kind of sailing you have in mind. We’ve been quiet about this until now, because we had no idea if it would work, and Craig is still experimenting with different plastics and thicknesses. I’m not sure what his intentions might be for production and pricing, but you might contact him to talk.

Bill

As the original Riptide is over 50 years old, I doubt that there would be any problems. Earl, as the resident vintage Marblehead guru, might like to comment, but the plans are there for all to see and copy (without commecial license).

As long as we are talking RG plans, Claudio did up a set for me. I’ve shared with a few others, but none on the water yet. In our off-line discussions, some feel it might become a “limited one design” since the lines are based on Claudio’s IACC hulls - the AC120 and the AC100. Since so many like the old Cup hull design, having a set of lines to build from will perhaps interest some builders. Why a “limited” one design? - Basically it will require the hull to “look” like an IACC hull and it would require a traditional rig. Otherwise it would follow the RG65 rules and would be class legal for either the RG65 or (whatever we call it) RG-IACC - or maybe the AC65 ??? Anyway, this winter is a time for building a copule, getting them on the water to see how well they sail. Once the kinks are worked out (if any) we will get approval to post here and in the French RG plan site.

Stay tuned for more info later in 2011.

Just thought I would mention in case there are some who like the design, but find the 120 and the 100 a bit on the “big” side.

I saw a couple McRigs on the Rg65s so far.

If you’re building a McRig for the RG65, what kinds of things would you need to do to make it work, and does it even work at that scale? Obviously, most things need to be scaled up, like the thickness of the Z-bend wire, which can no longer be a simple bicycle spoke, and should now be 3 or 4mm wire, and the upper arm much longer than the usual 50mm (probably 150 - 200mm.) The mast & boom need to be heavier; would you go with a round cross-section mast or an oval one? Are there any things that should be over-built to account for the bigger sail area and larger stresses, like the mast tube in the deck? Because there are no stays, it’s probably got to be reinforced more than you’d think. Because of the larger scale, you could probably forgo the simple tape attachments for the luff, head, tack and clew, and go with rubber grommets, string loops, and maybe some bowsies.

Has anyone documented a build for the McRig for RG65? It’s something to contemplate or fiddle with over the holidays or when you’re snowed-in.

thx

Tom, take a look at the pics from Albuquerque. It certainly does work to scale up a McRig. We did very well at the nats for a first-time effort. Also look at patbigs Cobra for a bit different approach to the rig.

We used 1/8" wire for the Z bend, I think spars were 6mm round, though the boom could be less, A rig was max height to the rule. I think Jims mast was tapered. Sails were attached with string loops. No special reinforcement needed for the mast tube.

For hull construction, Jim and Scott used 1/64 ply…I used 1/16 and 3/32 balsa. No prebending required.

Bill

Tom,
Looking back in old “Model Yachting” magazines, I have seen pictures of a 36/600 and even a Marblehead using what we now call ‘McRigs’. So they can be scaled up.
With a McRig (or swing rig) there are fewer stresses on tha hull than with the conventional rigs. As Bill said, I built my Cobra 5a with 1/64 ply. If you check the “hullkeel” picture in “Scott’s Cobra” on the Yahoo site you might be able to see that the only reinforcement I used was carbon strips around the hull near the mast. I put in diagonal bracing by the keel, but that was just from when I thought I’d use a conventional rig also. They were to transfer the keel load to the chainplates. I’ll leave them out of the next one I build. I used a bit of 1/64 ply decking to transfer the torque loads from the mast to the keel. The rest of the deck is "21 st Century Fabric and I haven’t seen any sign of stress in it. So I guess the boat is overbuilt!
Incidentally, the rigs pictured in “Scott’s Cobra” are the ones Jim used (with different numbering) in the Nationals. They used tapered, pulltruded, round, kite spars. Jim and I used tapered ones of different manufacturers, but there seemed to be no difference in speed. Or maybe Bill just outsailed us!
Scott

My version of the McRig, based on zero experience on the topic and looking at pictures from the Rio Grande Cup and Bill’s boats , plus some swing rig data. The black part of the main boom is a carbon fiber sleeve over hig density foam, doubled over the mast end forward, the mast is 7mm OD carbon tube, 6mm OD 70 % up. The back half of the main boom is lighter, just one layer of fiberglass either side. The pivot is using two ball bearing inside a 12 mm OD carbon tube. About 25% of the sail area is forward of the pivot axis. I still have to test it more extensively but it did very well in gusty conditions for a half hour, until the cold became too much for the skippers.

Uploaded with ImageShack.us
Patrick

Did you calculate where to put the mast into the deck, or go with a recommendation, or guess?

I have three holes for the mast step, center to center spaced 15mm, and the middle one worked for me. Its center is 56 mm from the fin’s leading edge. On my fin the leading edge is vertical, the trailing edge is oblique. Max width of the fin is 58 mm, minimum about 48 mm. Much will depend on the cut of your sail and rake of the mast, but something around 60 mm seems about average from the various sources I found on the web.
Patrick

thank you for answering, and I will try to build the minituxII.

I met Craig several months ago at the DC area Luekemia Cup, and I got to sail a few of his RG65’s I am making him some sails for one of the older boats and will proably put together a suit for a swing rig for him.

I met with craig to day and picked up one of the ranger hulls… Seems awful skinny… I think my skinny V-12 footy is beamier and is made with thicker materia…

But from the standpoint of an easy build… a vacuum formed hull from styrene makes a build pretty quick. so I hope… Since our club isn’t doing any footy’s any more…i figure i’ll ransack the servos’ from the footy and build an rg…based on the local sucesses of my delta rig footy… I’m going to follow suit with a delta rig rg65

with the tools that Craig has at his disposal I would imagine that the potential for many more shapes is very possible…

I hope to find out this weekend how the Delta rig works. There certainly seem to be less complications in setting it up than the conventional/swing rig options.

I laser cut a set of Ranger skins and built one up last week. with 1/32 ply it ended up at 3.5 oz. Was a lot stronger and stiffer than expected. Also a really quick build. Going to look at what it takes to cut from balsa to see if I can reduce the cost. Currently $35 or so to laser cut out of 1/32 ply and 1/64 ply is even more.

well I started the build last night… I wil take pics tonight when i get home… I trimmed the deck and hull to the proper lines, I reinforced the deck at the proposed jib attachment, mast step, shroud and backstay and rudder points…used a 1/8" Carbon/nomex sandwich I had laying a round… It will be a delta rig I figure I could reinforce the deck mid ships if I wanted to turn it into a sloop… I ransacked a keel from a footy for my rudder, and I have a leftover carbon heli blade that I’ll use as the keel…

I toyed with making the mast stepped in the hull but a deck step will allow for more adjustment…

Well we are doing the same thing. I got the hull glued up last week (after a first tial I glued the template on a 1/4 inch plywood and after cutting and fairing I used as templates to cut 1/16’’ balsa on a router) and I’m slowly fairing it, right now (no photos, sorry). Next CF reinforcemet inside the hull, by the keel, mast and jib attachment position. I was going to use the same rig (after reading your discussion with Claudio and your trials on the footy … btw the footy is next). My only difference I was going to try a Hoyt boom, do you have any suggestion on the sail dimension and construction? I was going to use claudio dimensions with a single pannel sail (I still have huge problems with a pannels sail).
For keel I was going to sandwich CF between two 1/16 balsa layers and fairing to a slight airfoil, I’m still not 100% convinced you need a airfoil keel on the RG’s (or footy for that matter).
Looking forward to your photos.