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First RC Build

Old 01-20-2021, 03:45 PM
  #1  
RKTLaunch
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Default First RC Build

After spending years scratch building free-flight models, mostly to R&D my own ideas, I'm finally going RC. I'm going to log my trials and tribulations... learning the electrics and piecing all the linkage parts together....and so on.

I'm only purchasing some things as I need them, and I'm still working in my CAD software, with about half done.

I started with twin JP Hobby 70mm EDFs, Tallon 90 ESCs, Futaba 6J transmitter, ev-peak 100w charger and one 6S 5000/30C battery for testing.

Now I'm putting a build board together as I'm building out of balsa and plywood. I used to have a manufacturered build board, but it was lost. After researching how people are building them, I purchased 1) 5/8s partical board and two drop ceiling tiles....might glue Sig's liteply on top, but don't know about that yet.

So far the most difficult part has been finding linkage parts for what I need. I don't know what they're called, but I'm making progress on that. I've got some servo arms, balls and links on the way.

So I'll keep a running log here. Suggestions welcome.

Thanks

Last edited by RKTLaunch; 01-21-2021 at 01:15 AM.
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Old 01-20-2021, 04:16 PM
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I'm building what I think is called "strip" ailerons, but bending my own music wire (kind'a have to), and using 4-40 sized turnbuckle, rod and balls for the linkage between that servo and the misic wire in the wings...most of that is ordered and on the way. Also ordered plywood and a Futaba 3003 servo (one for both ailerons). The wings are closed to finished in CAD, and testing my linkage will be the first order of business.

I have printed out a couple of the ribs. From my software to the paper, they seem to be consistently 1/64th of an inch under sized in both directions. That's not a problem as long as it stays that way. I'll just have to continue to check and measure the consistency as I print more part templets. It's a quality laser jet printer, so it should be good.

Last edited by RKTLaunch; 01-20-2021 at 05:48 PM.
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Old 01-21-2021, 12:31 AM
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Don Sims
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Good luck with the built. If you decide to post photos it's best to host them on another site and link them here or make them small.
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Old 01-24-2021, 07:40 AM
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I've been working on my build table, gathering tools and supplies...a little wood on the way. I should be cutting ribs in a week. I'm anxious to use my new scroll saw. It's only a Ryobi, but the user ratings were pretty good. I'll let everybody know if it's up to the task.
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Old 01-24-2021, 02:51 PM
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be careful, LOL. the building bug will bite you hard! I just started building myself a few years back and have fallen love with it! I started wit a small wood trainer and now I am just about to finish up this 15ft beast!
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Old 01-24-2021, 05:48 PM
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Originally Posted by firemanbill View Post
be careful, LOL. the building bug will bite you hard! I just started building myself a few years back and have fallen love with it! I started wit a small wood trainer and now I am just about to finish up this 15ft beast!
I know what you mean. I've built most of my life, but stuck to free-flight because I was, and am designing my own and felt a free-flight had to be RIGHT to work at all. I had wanted to start RC building, but it wasn't the right time....I stopped building for a number of reasons in '96. ...haha, but this is something I have to do, and I"m retired now. I've got the time.
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Old 01-24-2021, 06:44 PM
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Nice! I just retired back in September, Loving it so far.
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Old 01-24-2021, 09:03 PM
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Originally Posted by firemanbill View Post
Nice! I just retired back in September, Loving it so far.
The one I'm designing and building now, I came up with and built a mock-up for, just when I quit in '96. So it's about time I finished it. Might be my last. Balsa/plywood swept and tapered wings are hard...and I find myself making a couple stupid mistakes. The good news is I catch them, because I go thru each step several times to make sure. I used to do more drawing than CAD. Now I'm doing more CAD than drawing. It's more accurate, but harder...in many ways.
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Old 01-25-2021, 04:09 PM
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A bit of frustration, but I got an answer.



I ordered this and because I'm doing many things, later I thought to myself, "wait a minute, you've got'a have reverse threads on one end.....or it's not a turnbuckle. Got out my magnifying glass and sure enough. One side has reverse thread. So I called DuBro and ask, "which of your ball links are reverse thread?" Nobody had a clue what I was talking about. Nobody in the office or on the phone. They didn't know what reverse thread is.

Eventually, but not long, they called back and told me their ball links are "self threading". At least the plastic ones. You just thread them on.

Anybody ever have one of these plastic links strip out?

Thanks
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Old 01-27-2021, 05:33 PM
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I'm finally doing some real work....cutting the first couple pieces. They're really what amounts to test pieces. I expect to modify them, but it's been since '96 since I've done this so a couple of practice pieces makes sense.



Paper templets are a pain, but I've done 8 models this way and had good success at it. I was talking to Joe at BalsaUSA about the glue they have. I had always used Testors, I mentioned to him how I transfer CAD to wood using paper templets, he was a bit confused about my technique. Haha, who wouldn't be, he said they have three laser cutters. How nice, but I'd rather do this myself, so if there are any changes I don't need to send them off or have them done again. I just do it myself. I have had my CADs cut before, but it was for my Irwin32 Sloop. I moved the helm from the back, closer to the middle. I had to design a new mount for it and the cable runners to the rudder. I was fortunate that in Corpus Christi where my boat was, there was a great fabrication shop that could cut from my CAD work. They used a HYDRO cutter to cut the 1/4" 316 stainless steel I required.

I've never bought Ryobi before, usually DeWalt. Considering I may only make 2 more models, I didn't want to spend $400 on a scroll saw, and this one had good reviews from users.
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Old 01-27-2021, 08:21 PM
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.
No, I'm not going to post every detail, but I like assessing tools and techniques. I can't say I"m thrilled with the Ryobi, as I suspected, you get what you pay for, but with the correct blade it will do the job with a bit of extra effort. No surprise there. The first "part", I used the blade that came with the saw. Not so good. The second "part", I used an 18 tpi skip-tooth blade, it was better. I will most likely try the 20 tpi regular tooth blade and think it'll work best. The parts came out fine, with a bit of filing and sanding.



One of the biggest drags of this saw? Every time I pushed the wood across, it caught on the lip (see arrow below).



I think tho....a couple pieces of tape will raise the center up and that'll stop the wood from catching. It's either that, or I'll have to put a fine file and some Emory cloth to the table.

So far, early in my adventure. It's going as expected.
.
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Old 01-28-2021, 12:58 AM
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RKTLaunch
If its anything like my saw that plastic insert is 'pop out' removable so it would easy to use some packing (paper of very thin card) the raise it so it is flush with the table surface, which of course it should be.
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Old 01-28-2021, 01:47 AM
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Originally Posted by quorneng View Post
RKTLaunch
If its anything like my saw that plastic insert is 'pop out' removable so it would easy to use some packing (paper of very thin card) the raise it so it is flush with the table surface, which of course it should be.
Yep, same thing. I'm thinking if a couple layers of Scotch tape isn't thick enough, I'll try masking/blue tape. ....on the lip it sets on. I can cut it round, to fit nicely.
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Old 02-03-2021, 07:02 PM
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I got my big box of lumber today, almost all of it is on hand now. That means I have to make a final decision how to build the wings. I've got both 1/16th, 1/32nd plywood and a sheet of 1/16th balsa. I've always used 1/16th balsa to apply on the top of the leading edge to make it real smooth and it adds a lot of strength. So my decision is to either do that, run the 1/32nd plywood on the entire top of the wing....or use the 1/16th plywood along the top of the leading edge, instead of balsa. It all depends on how it bends, and which one I decide on effects the dimensions and placement of the spars. I like to leave the bottom of the wing with typical covering so if for some reason you need to open it up, it's easy. The reason I'm hesitant to use the 1/32nd ply, is because I know and remember that when sanding the leading edge you end up really glad you've got 1/16th of material there. Obviously, on a tapered wing, you can't just buy leading edge. It changes size down the length of the wing and of course my leading edge is a little different than what's common, so I'd have to sand it anyway.. I should be able to make that decision today....I want to get this show on the road.

Added: Yep, 1/16th balsa sheet over the top of the leading edge like I've always done it.

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Old 02-09-2021, 04:52 AM
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I think I'm going to install vortex generators in front of my rudder. My elevator is at the top of the rudder and I need a horn up there. On a 40" long model, that'll make the rudder thicker than I'd like....so vortex generators could make a difference.

Boy, there gonna be little bitty but I think I've figured out what I can use....haha, besides tweezers.
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Old 02-09-2021, 11:12 AM
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Interesting but I am not sure there is a relevance between a thick rudder and vortex generators.
As I understand it vortex generators are normally used on a lifting wing surface to control the the way laminar airflow breaks away to restrict the movement of the wing's centre of pressure . Unless a plane is out of trim a rudder is not 'lifting' at all most of the time but is normal to the airflow.
Unless of course your vortex generator is doing something different.
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Old 02-09-2021, 01:32 PM
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They're used in a few locations these days. Wherever you want to smooth out the turbulence. You can also use them further forward on the rudder if needed. Vertical or horizontal makes no difference.

Tho "organizing" the turbulence is a better way to say it, and I'll study more wind tunnel imagining before making a final decision.

I'm seeing them used to improve DC3s and on boat hulls....not restricted to wings.

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Old 02-10-2021, 12:51 AM
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Another example...on the B1 bomber.


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Old 03-21-2021, 06:56 PM
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Seems like I have to do things the hard way. Still lots of glue to clean off, and this is a test to see if this is possible.....obviously upside-down. The linkage runs thru the rudder below (first forward, then downward). Split elevator so there will be two of them. That's the hard part. Will they fit next to each other in the skinny part of the tail? NUTS, getting them the same will be hard.


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Old 03-21-2021, 07:58 PM
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Getting this close on the first attempt helps a lot. There's also a vise and 2Lb sledge involved. Tho backwards. The two uprights go together and at the moment they're longer than they need to be. I think I'm on the right track....or at least for what I want, it's going to work. Gluing them in, is going to be interesting. Is it really worth the extra effort to keep the control surfaces clean on a model (and keeping it lighter than a couple micro-servos)? I can't say it'll make a difference, but I think it's worth MY effort. That's all I can say.



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Old 04-13-2021, 06:51 AM
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Originally Posted by firemanbill View Post
be careful, LOL. the building bug will bite you hard! I just started building myself a few years back and have fallen love with it! I started wit a small wood trainer and now I am just about to finish up this 15ft beast!
I enjoy the building and really, solving the issues that come up. Admittedly, I'm a bit impatient tho. The biggest difficulty with this RC is the size. It makes the mecanical details very hard. ....but the EDF size relative to the model is specific, not to mention the room it takes up. To make a larger model....big enough to make the mecanical detail easier, I'd need 150mm EDFs. Never seen those, plus they'd still have to be counter-rotating.

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