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

TexMechsRobot

Posted a thousand or more times
I did take the bind plug out and the receiver did bind to the transmitter. I did try one motor and esc and got the same results. I'm going to try plugging in the satellite receivers first and see if that changes anything. Then I'm going to start swapping parts and see where that takes me.
 

nhk750

Aviation Enthusiast
Unless you deploy flaps as your going into a high speed high g maneuver, you probably will be ok with your built in bec. I have browned out similar ESC's but that was flat spinning at full throttle on a low battery. I think I saw some sort of formula on RC Groups but I cant remember where now.
 

TexMechsRobot

Posted a thousand or more times
One rule of thumb is .5A per servo. With a 4A BEC I could theoretically power 8 servos. But that's a real rough rule of thumb in my opinion. I'm more than likely fine but I'd like to have more confidence than just a "it'll probably be alright".

Also, plugging in the two satellite receivers that came with the AR9020 was all that was needed. It is literally not in the manual for the RX. I found that piece of knowledge in a 4 year old thread on RCGroups. The brick is inoperable without both receivers plugged into it. At least I'll have confidence in the ground to air signal while I'm flying!

I'm out of time for building tonight but I'll be cutting and gluing more balsa tomorrow now that November 1st is finally here!
 

nhk750

Aviation Enthusiast
We measure amp draw at work with a Fluke meter in series with the load up to 5amps with a standard meter, then for higher amp draws we use amp clamps and amp meters that can handle more than 5amps. So, if you have a meter that can handle 5amps you could put it in series with your servos one at a time and then add up the draw for a total or possibly connect in series with the battery, but I havnt tried that. You wouldnt want to throttle up or the meter fuse will blow.
 

TexMechsRobot

Posted a thousand or more times
Working on the fuselage. Apparently I should have started with the wing. I got to step 11 and it said "Use the assembled wing to place former 4B." I don't have an assembled wing.

So I'm going to finish boxing up the frame and then unpin it and work on the wing next.

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I love this build. The "stick and tissue" style suits me and it's going to look great once finished.
 

TexMechsRobot

Posted a thousand or more times
It's been a long weekend for me! I participated in a 24 hour fundraising event Saturday morning to Sunday morning and am still in recovery mode. I did get some work done while trying to stay away Sunday night and I took Monday off of work to try an get my body back on schedule. It mostly worked and I spent the day building on the plane and catching up on Critical Role.

So the build.

First off, I think it's going to be a beautiful plane that flies well. I learned a little bit about the design philosophy of Pat Tritle as it pertains to the fixed landing gear. He basically started in free flight models and there, weight is everything. He began converting to powered RC and doesn't subscribe to the mantra that "it doesn't matter how heavy it is because I can just add a bigger motor." In his view, a Cessna 172 shouldn't fly like a barnstormer. He builds to fly scale. I line up with this philosophy well so I'm looking forward to flying this kit.

Second, the wood in the kits is great. It requires a little bit of knowledge and experience to tell the difference but there are different densities of the same sizes so that the builder can make judgement calls about strength vs. weight. Also, the laser cutting is perfect. Couldn't ask for anything better there. I'll get a feel for how the laser cut parts actually fit together as I move to the wings this evening.

However, there are already several mistakes in the instructions and plans that a new builder might struggle over. I'll give one example because I took a picture of it. The rest are pretty similar.

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You can see that the instructions call for 1/16 square balsa whereas the wood in the kit doesn't include this. Luckily I have enough stock wood to make up for it. I ran into the same issue at a place where it called for 1/8" x 1/4" balsa. The kit was supposed to have one stick of it but it was nowhere to be found.

I'm expecting to run into more of these as I keep building. Overall, it's an easy kit still and I can't wait to finish it and get her in the air!

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Joker 53150

Mmmmmmm, balsa.
Mentor
The DC-3 is a wonderful subject - my preference is the C-47 Dakota version in OD Green. Some day... I had a couple Top Flite kits pass through my hands over the past year, but it's just not quite big enough. At a swap meet at the EAA a few months ago I picked up an old set of plans that are slightly larger at 96" (1/12th scale). It would make a great subject for some scale detail - the rudder and flaps, as example. They're easy to do wrong, and look fantastic when done right. A pair of gas engines would give it a great sound as well. Some day... The big stumbling block is the landing gear. It's also why I hesitate on building a PBY Catalina with retracts. Maybe I'll need to learn to do the necessary fabrication to make my own. Some day... :)

The inaccuracies/mistakes in build manuals really drive me nuts, and they make me wonder if the manufacturers ever test-build their own planes before releasing the kits! At least you aren't missing a ton of material, and it can easily be cut from sheet stock. That's a great example of why I love my "balsa stripper" and my "razor plane", as I can make just about any size stick needed from sheet. And since a square inch of sheet is far cheaper than a square inch of balsa sticks, you save money in the long run as well.
 
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Joker 53150

Mmmmmmm, balsa.
Mentor
But it's BARELY giant scale! :) Wingspan is about 82", which is certainly good-size, but in my opinion it would look much better closer to 100". The Top Flite kits are pretty nice and very complete. You can find good deals on them at swap meets or online, plus the kit is still made if you want to get one fresh-ish from the factory. At the last swap meet I was at somebody had a completed one for sale. It looked well-built, but I wasn't a fan of the color scheme used.
 

TexMechsRobot

Posted a thousand or more times
That's one I definitely want to build. I've had my eye on it for about 2 years now and it's really just a matter of having the money and the space to do it at this point.
 

TexMechsRobot

Posted a thousand or more times
I have the major structures built. The wing is in three pieces, the tail and stab are roughed in and the fuselage frame is assembled. Next is a bunch of sanding and shaping before I can move on.

I have to say, these instructions are terrible. I still expect it to be a solid model that flies well but if I weren't looking at the plans and relying on past experience, it wouldn't even hold together. Some of it is minor but others not so much.

For instance, it never actually tells you to glue the ribs to the trailing edge. Also, it never tells you to install ribs 6 and 7! They did send a CD that has tons of pictures of the assembly process so that helps fill in some of the gaps but the assembly on the CD starts with the fuselage and about 1/4 of the way through that, it tells you to use the assembled wing for reference (which isn't assembled at that point).

Anyway. Again, it's going to be a nice model and the parts go together beautifully. I'm looking forward to getting it into shape with the airfoil sanded in and the formers and stringers put on the fuselage.

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nhk750

Aviation Enthusiast
Wow, that is a really wide center section. Looking good so far. Since this is a fairly new kit you might want to send the creators an email with some of the stuff you have found. They might update the instructions for the next guy...like me...More pictures, I like pictures...
 

TexMechsRobot

Posted a thousand or more times
Wow, that is a really wide center section. Looking good so far. Since this is a fairly new kit you might want to send the creators an email with some of the stuff you have found. They might update the instructions for the next guy...like me...More pictures, I like pictures...

That's a good call. I might do that. Also, I'm trying to keep this thread under 17 pages unlike some people I'm related to ;)
 

Joker 53150

Mmmmmmm, balsa.
Mentor
Come on guys, what do you say we all three do a group build of Ziroli DC-3’s for next fall’s build off?! We could ask for a group rate on some Saito radials, lol.

I'm in! :) Or probably not. :( Those radials are a little rich for my blood!
 

rockyboy

Skill Collector
Mentor
If I win the lottery you're all getting Saito radials! :applause:

Course that means I'd need to play the lottery...
 

TexMechsRobot

Posted a thousand or more times
Moar building.

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This was my first time soldering landing gear. After some internet searching, I found that the best method is to wrap the joint in thin copper wire and then solder it. Since the struts are steel, they don't get hot enough to adequately take the solder so the copper wire wrap makes up for that. I created a cold solder joint just to hold it together and then wrapped it in the copper wire and then added more solder. In truth, none of the solder joints are load bearing so I'm not too worried about it.

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The landing gear are actually lashed to the thin ply with kevlar thread, CA'd, and then epoxied. The bracing strut is just there for a more scale look. The wire running into the wing is floating which will allow it to move on landing. If anything breaks, it'll be the ply that that main wire is lashed to.

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Now I'm starting on the flaps.

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Also, I set up a test stand for the power system to see what my power draw is. With the 3 bladed 7 x 4 Master Airscrew, I'm pulling about 12A and generating about 135W at full throttle on a 3 cell lipo. This model is expected to weigh in at about 2 pounds which would put me at 67 watts per pound. That seems pretty low to me since it's at full throttle but it is supposed to be a scale flyer. eCalc is telling me it'll be fine but I may try 7 x 5 as well to see if I like that better. I have plenty of room on the 30A esc's so that isn't an issue. Thoughts?

 

nhk750

Aviation Enthusiast
Nice test stand! Thanks for the vid on the power. This guy has a good write up on wpp. Watts per pound

I think your current setup is perfect for a start, especially for the scale look. Im excited to see this bird fly. The DC-3 never leaped off the ground, they were slow and low on takeoff.
 
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