Another proposed design by Roddie

NEW222 wrote:Those are well documented. I like your method of doing it on graph paper. Nice and easy to keep things straight. I don't know which I like best, as they all look great and well done.

Hey.. thanks Chancey! I appreciate that. The way I see it; I'll be gone someday.. and who-knows when. My models might not fly worth a damn.. but someone may want to build one of my designs someday.. just for fun. A drawing tends to last a lot longer than a model does.

I use epoxy where extra-strength is needed in a joint. Typically.. I use it in the nose-construction of my models. Tonight I installed/glued-up the nose-blocks for this model. This was a different-install.. in that the nose-blocks needed to be glued-in after the wing was installed. The plywood firewall-panels will be glued onto the nose-blocks.. after the nose-block glue has cured.




I may "pin" the nose-blocks.. as CEF member New222 (Chancey) recommended. More on that later..

You may ask "why" build a bellcrank.. It's not an easy task to source a small/half-A size bellcrank these days. I will admit that I had access to a CNC router-machine a few years ago.. and took the liberty of cutting some .040" aluminum bellcrank "blanks" in three sizes. (S-M-L) I chose the "medium" size for this model. It has a 1.625" lead-out spacing.

I'll be using .015" braided-line for the lead-outs.



Stay-tuned...

maybe overkill for this little airplane.. but I had the hardware to spend..



I enjoy making-up these assemblies for my "U-control" flying models. It's not something that's particularly popular these days.. but it is a practice that was popular back in the day...

NEW222 wrote:

roddie wrote:You may ask "why" build a bellcrank.. It's not an easy task to source a small/half-A size bellcrank these days. I will admit that I had access to a CNC router-machine a few years ago.. and took the liberty of cutting some .040" aluminum bellcrank "blanks" in three sizes. (S-M-L) I chose the "medium" size for this model. It has a 1.625" lead-out spacing.

I'll be using .015" braided-line for the lead-outs.



Stay-tuned...

I will be watching this part closely as well. I like the homemade bellcrank and have made a couple myself so far and have to make another shortly for another plane. I will post a new topic on that later today. However, I am always uncertain on how exactly to mount the bellcrank. Unlike the factory nylon ones supplied in the 1/2a kits or even in the larger .35 size kits that have a nylon bushing that does all the work for you. I do not mean the actual mounting location, but rather what is used for screws/pin and how to hold teh bellcrank in place. Looking better and better with every picture.

Hey Chancey!!! I hope that I can help you figure-out a few things here. Regarding the "mounting" of the bellcrank; be sure that there's hardwood surrounding the mount. There's generally "one screw" for the pivot. Be sure that it is supported adequately.

It's in your best interest to source some very thin plywood for your 1/2A C/L models. You'll use it for "fuse-doublers" on profile-designs.. as well as bellcrank-platforms.

Many years ago... I sourced some model-plywood from Sig Manufacturing Co. I bought x1 sheet 12" x 24" x 1/32" thickness plywood.. and x1 sheet of 12" x 24" x 1/64" thickness plywood. It's expensive.. until you calculate how much you need for a particular-purpose.

When your flying-models get smaller.. it's imperative that you build light... and strong.. if permissible..

A little more work on the engine-mount. I cut three pieces of 1/32" plywood and laminated them together to make a firewall. The 3/32" (.094") thickness seemed like a good compromise between 1/16" and 1/8".





I used a different epoxy for bonding to the hardwood nose-blocks.





I made punch-marks for the Cox .049 "Bee" engines and also for the horseshoe backplate/mount of the "product-engine".. but I should have marked the beam-locations, because the "horizontally-oriented" horseshoe mounting-pattern was off-center with the beams. This can be seen in the photo below.. (the first punch-marks for the horseshoe-pattern were too far to the left)



Luckily I noticed prior to drilling the screw-holes. I plan on using a product-engine configuration.. and did not drill the "Bee" mount-pattern.



If the model happens to end-up tail-heavy.. I'll have the option of swapping to a "Golden Bee" .049 which moves a considerable amount of weight forward.

I had previously butchered the horn-mount and had to fill and sand the holes and gouges from a screwdriver..  so.. I decided to reinforce the top/bottom of the elevator with 1/2" squares of 1/64" plywood. I should have done this from the beginning. The plywood will also help to prevent the underlying balsa from crushing when the horn is assembled.

NEW222 wrote:Looking really good roddie. I also like that you used teh reinforcements on the tail for teh horn. I realized it in the past that tightning it would crush the wood. However, I had used 1/32 ply as it was what I happened to have on hand. Also, what is teh dry time of the epoxy you are using? I have both 5 and 30 minute epoxy that I use here.

Thank you Chancey! Many years ago I bought 1/64" and 1/32" plywood from Sig Manufacturing Co. in Iowa. Both sheets were 12" x 24". I've used it for many things.. and there's still a lot of it leftover.

The "Devcon" epoxy used on the firewall is 30 min. cure-time... and is clear/colorless. The blocks behind the firewall were glued with 60 min. "Loctite" brand which cures to a translucent yellow. I haven't used the 5 min. cure epoxy, but I do have some. It is also Loctite brand and cures translucent yellow. The Loctite epoxy's are both "plunger-style" dispensers. I don't really care for them. The 30 min. Devcon is two separate tubes.. which I find easier to work with.

This may look simple.. but it took me several hours to fabricate..





The #5-40 central pivot-screw will be cut-off flush with the hex-nut... and "thread-locker" applied at finish. The thimbles on the bellcrank are made from #3-48 cap-screws and 5/32" brass-tube bushings, small fender-washers with #3-48 lock-nuts retaining them. The lead-out cables were re-done using .015" braided SS line. I still need to work-out a guide-arrangement for the lead-outs.

NEW222 wrote:Where on earth did you get the 3-48 cap screws? I have been looking for some to use on my Fox .15x as a couple of the screws stripped, and I have not had any luck locally. I have a couple regular screws to use, but would have preffered cap heads. Do you have a local screw supplier that stocks them?

PM me your address Chancey.. and I'll mail you some. I sourced a box of "100" 3-48 x 1.000" length through a company called "Fastenal". I also sourced 4-40 and 5-40 x 1.000" length black-oxide cap-screws from that same company. I have glow-engines that use these sizes. The 6-32 and larger sizes are commonly available at local hdwe. stores in my area.  

NEW222 wrote:Thanks for the reply and help roddie.I have heard of fastenal, and will give them a look. I appreciate your offer, however, after looking at them on their site, they would not unfortunately work.  I need all thread for the engine. But I will be coming back down in early April, and there is one in Grand Forks that I will be definitely visiting.

I'm assuming that your Fox .15X may possibly need back-plate screws? I can't imagine what-else could possibly require "all-thread" on that engine. Certainly not the head.. ?      

Here's a photo of the screw that I have.. against an inch scale/rule.



There's approx. 12/64" that's unthreaded under the head. Let me know if you think this screw might work.. and I'll mail you some asap.

not really a big deal.. but I took the time to make and install a pushrod guide tonight. It's made from a small safety-pin with the clasp cut off.




I inserted a "drill-bit" through the "eye" of the guide.. and then used needle-nose pliers to squeeze the two "legs" together until parallel. (the drill-bit keeps the safety-pins' eye concentric while applying force to the coil.) I trimmed the legs to the proper length.. and pressed them into the balsa, at the mid-point of the pushrod.. while the fuse was supported on the opposite side.

I then removed the guide and roughed-up the legs with an emery-board for better glue retention. I used thin CA glue to finally attach the guide.

The next step will be to make some small "fillets" at the wing and stabilizer roots. Then we'll almost be ready for the 1st coat of sealer/primer..

I picked up some "DAP" brand Plastic Wood filler.. and applied it to my airplane tonight. I'm not sure if I like it as much as the Elmer's-brand wood filler.. but the Elmer's was starting to harden in the tube from age.