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MauricioB's

"Cox Tee Dee .010"



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Time to put this one to bed

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Time to put this one to bed

Post  batjac on Thu Sep 10, 2015 4:36 am

Last year I cut out parts for two airplanes to use the Cox foam wings, one for a TD and one for a Black Widow.  I built the TD version as seen in this thread, and put the Black Widow parts on the shelf.  From time to time as I was cleaning up or looking around for things, I’d see the parts and think about finishing the second plane, but there was always another project to get to.

Well, lately the Churchyard field across the street from my house has been dry and brown from the hot weather.  I’ve not been wanting to fly there, as I could just see me starting a grass fire with one of my nitro engines.  Burning down a churchyard.  REAL bad mark in my folder on Judgement Day…  So, I figured I need a good 1/2A size electric plane other than my “just adequate” electric coroplast PT-19 Trainer.  I’d thought about using some Cox wings for an electric, so I went ahead and pulled the FW-190 parts off the shelf and got back to it, deciding it was time to finish it off and put it to bed.  Nothing fancy, just a single color fuse and the wings.  Just something Quick and Dirty.  Out came the parts and the plans:




Finishing out the fuselage I cut out, I started with the doublers.  The plans call for ½” balsa blocks for the cowl blocks, but I decided on 1/16” ply doublers instead.  After gluing those in place, I aligned and glued in the wing spars.




The plans call for a bellcrank in the wing, and that’s what I did the first time.  But I wanted to emphasize the “quick” part.  I like the Cox plastic wingtip, and the inboard one has the leadout guides molded into it, so I’m going to use that.  ‘Sides, it saves me the time of cutting out and shaping balsa wingtips.   On the Cox ME-109 Super Stunter, the lines go above the wing into the fuselage instead of through the wingtips and into the wing.  So, I’m just going to externally mount the bellcrank.  I chose the location for the bellcrank and drilled the spar for the mounting screw.




Next step was to fabricate the pushrod.  Here’s the method I like to use.  First I make lines on the stab to match the sides of the aft fuse.  Next, I mount the control horn on the elevator.  Then I tape the elevator to the stab and put pins along the lines I drew.  The pins jig the stabilizer straight and square while I’m marking the pushrod.





Then I mount the bellcrank to the spar and center it, slide the stab into the cutout in the fuse, and put one end of the pushrod through the control horn with the elevator held in the neutral position.  The pushrod already has the z-bend in the elevator end, and a dogleg bent into it for later fine adjustment.  I then lay the pushrod on top of the bellcrank and mark the location of the bellcrank hole on the pushrod with a black sharpie permanent marker.





Once I have the location marked, I remove the pushrod and use my new favorite tool to put in the z-bend.  This is the tool I should have had 25 years ago.  It makes a perfect z-bend.





Then I cut off the rest of the rod with a Dremel tool, and here’s what I’m left with.




Last thing for tonight is to mark the hinge line on the 1/16” tail surfaces, insert and glue in place the thread hinge, and then glue the stab/elevator in place.  I’ve never really found a good thread I like for the thread hinges, although I’m coming to love thread hinges for my 1/2A control line models.  So, I’m now experimenting with using 10# Spectra for the thread.




More to come…
The Cliffhanger Mark
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Re: Time to put this one to bed

Post  larrys4227 on Thu Sep 10, 2015 5:40 am

Nice!! Love build threads ..... keep 'em coming, and good job on the sewn hinge line. Smile
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Re: Time to put this one to bed

Post  getback on Thu Sep 10, 2015 9:01 am

Looking good Mark, I have one of those Z bender tools and cant ever get the right bend I want in small wire / is there a certain way to use this tool or just too small wire like .040-.050 ga. range ? I see yours came out nice ! Eric This Site Rocks!
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Re: Time to put this one to bed

Post  RknRusty on Thu Sep 10, 2015 9:12 am

I'm watching with interest...

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Re: Time to put this one to bed

Post  roddie on Thu Sep 10, 2015 8:57 pm

Yea.. that's a cool tool, that Z-bender. I'll admit; I cheat when it comes to making pushrods. I'm frugal with music-wire. The thought of getting the length wrong and having to make another one irks me.. but then; I don't usually add an adjustment-bend (dog leg) either. I make the length "close" to where the bell-crank will mount.. then I lock/clamp the elev. to neutral, with the pushrod installed on both; it's horn.. and in the bell-crank hole. I then position the bell-crank to neutral, and drill "its" mounting-hole. I've always used 1/16" dia. music-wire for my 1/2A size profile designs. It's overkill.. and heavy, but here's where the cheating comes in.. My Rare Bear Speed Contest model utilizes two "L-bends" in the pushrod ends. I used sm. washers.. ("Hob-bits" 0-80 size) and the "Goldberg" type spring-style wheel retainers to secure it. I also generally position the elevator horn so that the pushrod is as close to the profile fuse as possible.. along with the bell-crank. It keeps the weight of the control-system close to the centerline.

I hope you never misplace those pliers.. but here's the L-bends I made for the Rare Bear.




If you make rub-plates for the pushrod (1/64" plywood for example).. and get your elev. horn close enough to the fuse.. you don't actually need to retain the ends. I like to take these clearances into account when installing the controls.

This Focke Wulf is a nice looking model. You're putting an electric motor on it? I'm very curious about that. I accidentally lit a sizable beach-grass field afire years ago on July 4th, when a "jumping-jack" firework ricocheted off a stone in the street.. and went sailing into the grass. By the time it took to run over... the flames were 6 feet high. It was a spectacle... About an acre of beach looked like a war-zone after the fire department left. Not one of my better memories...
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Looks so good

Post  jmcalata on Fri Sep 11, 2015 12:50 am

Wooooow it´s beautiful, it´s a fantastic CL Rare Bear.
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nice job on the bellcrank

Post  happydad on Fri Sep 11, 2015 1:32 am

roddie wrote:Yea.. that's a cool tool, that Z-bender. I'll admit; I cheat when it comes to making pushrods. I'm frugal with music-wire. The thought of getting the length wrong and having to make another one irks me.. but then; I don't usually add an adjustment-bend (dog leg) either. I make the length "close" to where the bell-crank will mount.. then I lock/clamp the elev. to neutral, with the pushrod installed on both; it's horn.. and in the bell-crank hole. I then position the bell-crank to neutral, and drill "its" mounting-hole. I've always used 1/16" dia. music-wire for my 1/2A size profile designs. It's overkill.. and heavy, but here's where the cheating comes in.. My Rare Bear Speed Contest model utilizes two "L-bends" in the pushrod ends. I used sm. washers.. ("Hob-bits" 0-80 size) and the "Goldberg" type spring-style wheel retainers to secure it. I also generally position the elevator horn so that the pushrod is as close to the profile fuse as possible.. along with the bell-crank. It keeps the weight of the control-system close to the centerline.

I hope you never misplace those pliers.. but here's the L-bends I made for the Rare Bear.




If you make rub-plates for the pushrod (1/64" plywood for example).. and get your elev. horn close enough to the fuse.. you don't actually need to retain the ends. I like to take these clearances into account when installing the controls.

This Focke Wulf is a nice looking model. You're putting an electric motor on it? I'm very curious about that. I accidentally lit a sizable beach-grass field afire years ago on July 4th, when a "jumping-jack" firework ricocheted off a stone in the street.. and went sailing into the grass. By the time it took to run over... the flames were 6 feet high. It was a spectacle... About an acre of beach looked like a war-zone after the fire department left. Not one of my better memories...  

Roddie: You are a man after my own heart.  Such a nice job on the bellcrank leadouts. I ALWAYS use thin solid wire. The plane looks great. When will we see a video?

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Re: Time to put this one to bed

Post  roddie on Fri Sep 11, 2015 8:50 pm

happydad wrote:

Roddie: You are a man after my own heart.  Such a nice job on the bellcrank leadouts. I ALWAYS use thin solid wire. The plane looks great. When will we see a video?

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Re: Time to put this one to bed

Post  batjac on Sun Sep 13, 2015 12:59 am

getback wrote:Looking good Mark, I have one of those Z bender tools and cant ever get the right bend I want in small wire / is there a certain way to use this tool or just too small wire like .040-.050 ga. range ? I see yours came out nice ! Eric This Site Rocks!

Eric, I can't think of any time it didn't work for me. I'm not sure what the smallest size wire I've ever tried it on is, but it's always done me right.

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Re: Time to put this one to bed

Post  batjac on Sun Sep 13, 2015 1:09 am

roddie wrote:Yea.. that's a cool tool, that Z-bender. I'll admit; I cheat when it comes to making pushrods. I'm frugal with music-wire. The thought of getting the length wrong and having to make another one irks me.. but then; I don't usually add an adjustment-bend (dog leg) either. I make the length "close" to where the bell-crank will mount.. then I lock/clamp the elev. to neutral, with the pushrod installed on both; it's horn.. and in the bell-crank hole. I then position the bell-crank to neutral, and drill "its" mounting-hole.

Roddie,

I do that too for sheet wings, even though I usually still put the dogleg in anyway. But, since I have to mount the bellcrank to the center of the existing spar on this one, I had to do it the way I did.

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Re: Time to put this one to bed

Post  batjac on Sun Sep 13, 2015 1:14 am

Well, I had a couple of hours free this evening, so I put some time into the new plane.  I cut a firewall from 3/32” ply and glued it in place.  Then made a couple of blocks behind for support.  I drilled holes and mounted the motor mount to the firewall, then installed the motor.






A quick fitting of things before retiring for the evening.  The nose looks extremely long with the motor in place, but it balances out close to where it’s going to need to be.




The Retiring Mark


edit: I couldn't leave well enough alone, so I measured the length of the electric motor as compared to a Black Widow installation. The electric motor is actually almost 3/4" shorter to the prop flange than a Black Widow would be to the prop flange. Hmmm...

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Re: Time to put this one to bed

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