2017/2018 Balsa Build Along Dare/Brodak DC-3

[TexMechsRobot]

I'm in for my build! I settled on the Dare DC-3 by Brodak designed by Pat Tritle. It is a 1:19 scale stick and tissue style build that comes in at about 32-35 oz's depending on builder's choice in some areas. Wing loading should be about 11.5 oz/sq. ft. so it should be rather floaty. It has scale flaps and fixed landing gear. I would like to build custom scale retract but I think that's a little out of my league for the moment. Maybe it'll be an addition to this bird at some point in the future.



It come with the decals for a Delta Airlines livery. As an employee of Alaska Airlines, I wanted to model it after an iconic early Alaska plane. I contacted Callie and she was able to whip up a set of decals that should do the trick nicely. She is actually a friend of Pat's and so was able to customize them to the plans so I'm hoping for a good fit. This is my first time using her work and I've heard nothing but good things so I have high hopes!



I'm powering it with 2 Suppo 2217/9 motors swinging 2 three blade 7x4 Master Airscrew props; one CCW and one CW. The ESC's are 20 amp and it'll run on a 3S 2200mAh battery.

I expect it to fly scale and not aerobatic (which is kind of my style anyway). I'm looking forward to building it so much that I couldn't wait for the November 1st start date so I've jumped the gun a little...

 

[Joker 53150]

Early building? Shame on you!

Looks like a great kit and subject to build, I look forward to your work. Callie does some very good work, and I've been very happy with the vinyl she's done for me.

 

[TexMechsRobot]

I tried to keep myself preoccupied with plastic scale models but I finished the last on on Saturday. I couldn't just sit for a full week without building something! I do have some evening and weekend plans so it'll slow me down a little and give the rest of you rule followers a chance to catch up.

 

[rockyboy]

I'll bet you open Christmas presents on Christmas Eve too, don't you?

That's going to be a great looking model - I'm thinking of asking Callie to do a decal set for a project too, so interested to see this one progress.

 

[nhk750]

This is so awesome! I was just at the Boeing flight museum last week doing some work and also got a free tour. Im excited to see how your replica comes out as I'm very interested in this plane. It's on my list...which is growing out of control.

 

[TexMechsRobot]

I'm going to try out these props. The build calls for 7x5 APC 2 blades and my math tells me the 7x4 3 blade will work similarly. I'll probably round the tips a little and paint them yellow for a more scale look and then do a bench test with a watt meter to see what they are pulling out of the battery.

 

[rockyboy]

Those should work great - and look great too!

 

[nhk750]

That will look really nice. If you can shoot a video of the watt meter, I am interested in seeing the results in real time. I am going to love this build, one of my favorite planes.

 

[TexMechsRobot]

I'm new to clockwise propellers. Is the hardware that comes with the motor good enough if I use threadlocker? I know for a CCW prop, the spinning prop actually tightens the threads so it makes sense that a CW prop would try to loosen them. Do I need to find new hardware for this?



I could always use nylock nuts but I like the little spinner hub.

 

[rockyboy]

I think you'd be fine with a little thread locker in there - I've been running a similar setup on my Mini Guinea Pig w/o thread locker and no issues. Do make sure the prop is balanced and you won't be dealing with the kind of vibrations from wet fuel engines that really shake things loose.

 

[nhk750]

Ya, I would use some blue locktite and coat the threads. I have read countless threads with the same issue and that is what they do. On another note, I will be at the flying field around 4 pm for some air time before the rains come. Tomorrow I break out some wood for the Hog Bipe build start.

 

[TexMechsRobot]

Thanks for confirming my suspicions. I've got some blue threadlocker so I'll just stick with that.

On the flying note, not for me today. I've got to solder up a y-splitter for my battery to power two ESC's and motors. I'm building a test stand to test both motors running at the same time to test my amp draw and watt output.

I stopped building because I felt guilty but THAT ALL ENDS TOMORROW! Back to balsa building baby!

 

[jsknockoff]

Yeah definitely use thread locker. I have a mini arrow that spins in the loosening direction and it’s kicked the prop several times. Also I use a lot of the Master Airscrew electric props and I agree they look and perform great.

 

[TexMechsRobot]

I tried to get my motors and ESC's connected and bound up tonight. It didn't go as planned. I intend to use 2 motors, 2 ESC's, and 1 battery to power all of it including the RX.

I followed along with this video. I bound the Spektrum AR9020 RX to the TX without much trouble but the ESC's never activated and the motors didn't respond to the throttle input.

I'll add pics of my wiring in the morning.

Initial thoughts? I'm not really sure where to start. Electronics always get the best of me lol.

 

[Joker 53150]

Did you disconnect one of the ESC power wires like they mention? Does each ESC work if the other isn’t hooked up? Is the Y harness good? Have you tried running the ESCs on different channels, which could also give you thrust differential? That’s all I can think of!

 

[TexMechsRobot]

I did disconnect one of the ESC positive wires. The servo Y-harness is purchased so I expect it to be good. I have others to try in it's place though if that seems like the trouble part.

Here are pics of the setup.

















After I posted this, I tried to set it up as a single motor arrangement. Battery to ESC (the one that still had the positive connected) to motor and RX. I did not rebind the RX though. When I plugged in power, the RX would light up with a positive bind signal but the ESC didn't initialize or respond to throttle.

I pulled out another RX and tried to bind it but it wouldn't go into bind mode so it may be bad. I have other motors, ESC's, and RX's so I should be able to troubleshoot my way through this with known working parts.

 

[nhk750]

That's a nice rx, it has a failsafe smart start system, did you activate it? Also with 9 channels, why not use two channels for the esc's and have the option of differential thrust? I'm no expert on this, just some ideas.

 

[TexMechsRobot]

That could be my issue. I didn't even know I needed to do that. This is the RX that came with the DX9 Black Edition and it's the only one I have lying around at the moment other than the one I think is broken. I only need 5 channels at a minimum (Motors, Elevator, Rudder, Ailerons, Flaps) and could go up to 7 if I separate the motors and the ailerons. It would make sense to go to 6 channels and just separate the motors since I don't have a need for flaperons.

I did start trying to read the manual that came with the AR9020 but didn't notice anything right off the bat. I'll do more research in that area and see what I come up with.

EDIT: I also just read that this receiver will not work unless both satellite receivers are plugged in. I had removed one of them because I didn't think I needed two but some people are saying it won't work with just one or none. Another thing to try once I get home.

 

[TexMechsRobot]

I opted for 30A ESC's with 4A SBEC's built in. I plan to operate 4 of the EMAX ES9051 (4.3g) servos and 2 of the Emax ES08A II (8.5g) servos per the kit instructions. How do I calculate if a 4A SBEC will power all 6 servos? I don't have a multimeter or any inline, onboard meters to test this right now but I'm not opposed to buying something that comes highly recommended. I'd prefer a math solution and rules of thumb though.

It is unlikely that I'll ever be stressing the servos to their max very often. I plan to fly this plane very scale and it is pretty light as is. 2 of the 4.3g servos will power the flaps, 2 of them will power the rudder and elevator, and the 8.5g servos will run the ailerons. With that, the highest amp draw should be on landing when the flaps are deployed but the stcik movements will be slight.

I imagine I'm good to go but I'd like to understand why and be able to make the decision for a higher amp BEC or RX battery in the future.

 

[Joker 53150]

Silly question, but you did take the bind plug out after the initial bind? Or were you unable to get it to bind at all?

If you're still having issues with both motors I'd simplify it by setting it up as a single motor & ESC and verifying that works. Then start swapping components to verify everything works before hooking it up as a dual motor system with a Y harness. You'd also be surprised how many Y harnesses are the cause of problems, so watch that as well.

And as has been stated, going with each motor on it's own channel isn't a bad idea and it removes one potential failure point from the list (the Y harness).