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Yes it is...I will also try other fin shapes and sizes to see what works best. I will try to fabricate them myself using .050" sheet metal purchased at Homedepot.
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Glad to see Dick is back at making fins. He wasn't doing them for a while but has always been known to make some of the best turn fins on the market. On all my builds I have emailed him to make me a fin but at the time he was laid up and not making them. it may be time to shoot him a new email.Team Liquid DashComment
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I finished sheeting, sealing, and glassing both sponsons.
I used a framing square to get the fin mounted perpendicular to the sponsons and 6-32 bolts and blind nuts to secure it. I really like having 4 bolts to mount the bracket.Comment
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Motor mount and strut installed.
I got my motor and strut installed. I used my UL-1 motor mount to secure the motor to the formers. It worked well. I'm using Speed master hardware for the strut and rudder.
I also cut out the hole for the stuffing box. I'm using 9/32" brass tube for the stuffing box, and 1/4" brass tube for the stuffing tube. The 9/32" tube will be permanently glassed in place and the 1/4" tube will slide through it.
BTW I'm using .187" flex cable with NO teflon liner.Comment
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Duc,
Just wanted to cut-in and say "You do nice work!".
BobComment
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Does anyone build these and sell them?.NAMBA20...Caterpillar UL-1, P-Spec OM29, P-Mono DF33, P-Spec JAE, Aussie 33" Hydro-LSH, Sprintcat CC2028 on 8s, PT SS45 Q Hydro, PS295 UL-1 power, OSE Brothers Outlaw QMono 4-sale, Rio 51z CC2028 on 8s
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Thanks Bob!Comment
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I finished glassing the stuffing box in place, bent the stuffing tube, and cut the .187 flex cable to fit.
I also received my pushrod seals and mounts today, so I will be installing these next. The mount gets glued into the hull, and the seal slips over it. This makes replacing pushrod seals a snap. No more gluing the seals to the hull.
I'm installing the seal on the inside of the hull as there is not enough room between the transom and the tiller arm of the rudder for the seal.Comment
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Ohh..I like those pushrod seals!
So where prey tell did you get those from?-Tom MihelichComment
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Got'em here: http://redlinemotors.us/#/radio-equipment/4526084178
I've been getting a lot of cool ideas from the nitro and gas guys in my District. Another cool trick I learned from them is how to bend a stuffing tube without a tube bender. You kneal the tube with a propane torch, then quench it in water. This softens the brass. Then cap one end of the tube and fill it with water. Freeze it and bend away. The tube doesn't collapse because of the frozen water inside.Comment
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Speed master rudder installation
The rudder is now mounted, the servo is installed, and the pushrod has been fitted.
I used a Speed Master mini hydro rudder (1.5” setback). The Whiplash instructions call for trimming ¾” off the bottom of the rudder so I still need to do that. I did choose to do one “mod” to the Speed Master mounting bracket. The bracket is designed with a break away bolt, but is setup for use on the right side of the strut. Since the Whiplash instructions call for installing the rudder on the left side of the strut, I had to file an additional radius on the bracket to utilize the breakaway feature on the left side. No biggie.
I used a Hitec HS-645MG servo and the servo mount from my UL-1 to attach the servo to the hull. I simply flipped the bracket around and made a box to attach it too. I flipped the UL-1 mount around to make servo removal/replacement easier (2 screws on top). Pics below.Comment
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I decided to test my component placement and center of gravity prior to gluing the top decking on. As you can see in the pictures below, this is what I ended up with. The boat balances at 7/8” behind the sponsons. Others have mentioned a CG at 1” behind the sponsons, but I figured it was better to have the CG too far forward to start with… it is easier to shift weight rearward later.
To achieve a CG at 7/8” behind the sponsons with everything as pictured below, I had to add 1.25oz of lead to the tip of each sponson (2.5oz total). I hate adding “dead” weight, but at least I can do it now before the top decking gets glued in place. I’d rather have it hidden under the decking than in plain sight.
BTW: I don’t really like where the ESC is, but it was necessary to get the CG. I may move it elsewhere after the decking is glued on.
Current weight as pictured below is 5lbs. I’m not too worried about it being a little heavy as I’m building this boat for heat racing.Comment
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Fiberglass insulating exhaust header tape wrapped around the esc will help keep boat from going up in flames if the esc burned. Maybe the fiberglass wing tape would retain the flames
I also used the hollow carbon fiber tubing for my rudder linkage. Simply slid and glued tubing over 440 rod then slid aluminum tubing over end to prevent splitting. Rudder rod seems more rigid now. Epoxy applied on ends should work also.
Nothing wrong with adding lead weight. Adding a little more lead to left sponson tip should help keep boat planted during accelleration. If using a seperate receiver battery pack COG will be easy to adjust.
...Last edited by detox; 09-24-2009, 05:51 PM.Comment
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Yeah. I'm a bit worried about an ESC fire in there too.
I might try it there with the suggestions you made (glass insulation.) It depends where the CG lies after the decking and glass work is done.
I like your CF pushrod attachment method.
The aluminum sleeve is a nice touch. I had some of these left over from an airplane build and used them, but your method looks just as good. http://www.centralhobbies.com/contro...e/pushrod2.htm
I think using CF tube is a great way to reduce pushrod flex with long distances between the servo and rudder. The large scale aero guys swear by them.Comment
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