cheezer1222

My Feedback: (3)

So, I finally got around to building my little brodak trainer after about 2-3 years of sitting on the shelf. Unfortunately the supplied engine mount is made for a cox babe bee or black widow, and I have a cox sure start. From what I see, the difference is that the babe bee/black widow use an attached fuel tank, whereas the sure start looks like it uses an external tank. Is that attached tank compatible with the sure start? If so, does anybody have a site where I can pick up one or two of them real cheap? Is it it just as easy to throw on an external tank? Any advice or suggestions are appreciated.

controlliner

Check here.

http://coxengines.ca/product.php?pro...&cat=25&page=3

Remember if your engine has the dull grey crank case (cast), tell the company and they will give you the proper hardware for it. If your engine has the silver crank case (extruded) the kit comes with the proper hardware

cheezer1222

My Feedback: (3)

$20? Really?! I was kind of expecting it to be just a few bucks. Sticker shock, I guess. That's twice what I paid for the engine itself.

jcralley

Just modify the motor mounts for the sure start and go with an external tank. 

controlliner

It's in Canadian currency

cheezer1222

My Feedback: (3)

lol. I didn't even notice that it was a canadian site. If I do go with an external tank, what size is recommended? Would I also be using smaller fuel line?

I have a few questions about the kit as well. It has a strip of paper with airfoil templates (root and tip). How do I use those? I don't normally do much building and sanding and all that good stuff, I have a few ARFs that I've assembled, but that's about it, and these instructions seem to be aimed at a somewhat proficient builder. In other words, a lot of the information seems to be implied. Instead of me just guessing and messing it up, I figured I'd ask some of the more basic questions that I don't know, so that I don't mess this up.

Also, I thought the wing was pretty symmetrical, but now that I look at it, I may have glued it in backwards. Not sure if I did, it's not super obvious (to me, anyway), but if I did, would it be possible to just sand it the way I want it, or am I pretty much screwed? (I get a little too ambitious with my gluing sometimes)

Falco250

You could try a film canister fuel tank:

http://www.rcuniverse.com/forum/m_86...tm.htm#8635213

gcb

The templates are used to monitor progress as you sand or cut (razor plane) to airfoil shape. You cut out the bottom parts of the paper shape and occasionally place them over the wing. No need to be a proficient builder, but you are stepping up from assembler to builder.

Look at the plans, then look at what you have to determine if it's backwards...upside down? If it is backwards, first question is what type of glue did you use? You might be able to remove it with the correct solvent. Otherwise, round off what is NOW the leading edge and taper what is NOW the trailing edge. It might not fly as well as it could have, but it WILL fly.

You don't suppose that you are the first person to ever glue the wing on backwards. [&o]

Next kit, read and understand the instructions before setting glue to balsa. (That said, we all sometimes get anxious.)

Good luck, and ask any questions you have along the way...preferably before glueing.

George

paw080

Hi cheezer, those airfoil templates are just that; you are supposed to match the templates to the wing as you shape(carve/sand) the wing.

The model was designed by Jed Kusick approximately 40 years ago for Jr High/intermediate school children. The model is almost as easy to

assemble as a slip together balsa glider; with the added complication of engine mounting and control hardware. I know that many of these

models were assembled with backwards wings, backwards empannage, and very offset fuselages.

You can buy the original golden bee size fuel tank, or you can epoxy a 3/16" plywood radial engine mount with balsa cheeks for support,

whatever..it's up to you. Going with an external tank may difficult; because you'll need a 1/2 - 3/4 oz size, you need fuel tubing that

fits. Yes, small size should work. good luck;

Tony

cheezer1222

My Feedback: (3)

Yeah, I used thick CA and plenty of it. That wing isn't coming out without taking half the fuse with it. It's no biggie, I'll do like you said and sand it to the right shape. Luckily this kit was pretty cheap, so I won't be too heart-broken if it doesn't look or perform exactly how I want.

That seems to be my only issue with this little kit. The plans are nice, but the instructions just seem to be an afterthought. For example, no where in the instructions does it even mention using the airfoil templates. Putting this together isn't rocket science, but for a trainer (possibly somebody's first plane ever), I would concentrate on leaving out no minute detail when telling them how to put together their new plane.

I'll probably just buy the fuel tank and put it on there. I would imagine it'll be the easier route to go.

I wanted to thank everybody for their help in answering my questions. I'd let you all know how it flies, but I'm guessing I won't find out until next spring. One last noobie question for now, what size/length wire should I get for my plane, and where's the best place to get it?

gcb

There is a debonder (nitro methane) for CA but it may require more effort than you are willing to spend on it.

You might want to list all the things you found confusing and contact Brodak with that information. It's hard to envision ALL of the problems someone might encounter.

When I built mine to teach some kids to fly, I had many years of experience and encountered no problems.

It is the easiest way, but if you decide to go with the external tank, one is suggested on the Brodak site.

George

cheezer1222

My Feedback: (3)

Thanks for the heads-up, I missed that. I might do that after all. The tank they suggest is a 3/4 oz wedge tank. Does that sound about right? That seems kind of small. Any recommendations on mounting it? Placement? Do I just zip tie it on there, or is there a preferred method?

gcb

OK, here goes...
The tank should be mounted behind the firewall (engine mount) on the outboard side, with vertical center of tank at center of needle valve.

Since you are using a Sure Start, you need to create some type of standoff to secure the engine to the firewall yet accommodate the choke tube...or you could remove the choke tube, but that requires shorter backplate to crankcase mounting screws. I think the choke tube is 1/4" behind the mounting plate. A couple of 1/4" square pieces of wood, harder than balsa should work. One builder uses a "U" shaped piece of 1/4" plywood.

Mount the engine with cylinder pointing inward so the tubing going to the tank is pointing to the outside of the circle. Along with the tank you should order a foot or so of small fuel tubing, although in that position you will only need a few inches.

Personally, I would use the "U" shaped plywood as the firewall and a solid triangular piece of balsa on the inboard side of the 1/4" fuselage with grain running vertically, and an upper and lower triangular piece of 1/4" balsa with grain running with the long side of the triangle (gusset) on the outboard side. This should provide enough space between the gussets to allow space for the tank.

This is merely a suggestion of what I would do to use a Sure Start. Mine actually has a Cub .049A which has a tank that fits the supplied nylon mount. BTW, mine broke twice just behind the nylon mount so I installed two popcicle sticks mounted sideways from the front to a couple of inches behind the mount. So far, so good.

George

Edit: Oops, missed part of the question...rubber bands will hold the tank on fine and will allow for adjustments.

balonchange

lol,i want to have a try.