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Bird of Time Balsa Kit Build Thread

Craftydan

Hostage Taker of Quads
Moderator
Mentor
Tex,

Glass as Primer. I like the way you think ;)

Ran into the same trouble with linkages. started off with low-end 9g tower pro's, with a touch more bend than they liked . . . No dice. would struggle to move at all and couldn't center.

Swapped out a beefier servo (MG-92B), switched to a open-sided tandem setup, then let the servo find it's own happy spot along the width:

DSC04001.JPG

it's only by chance they're both so close to centerline. you let the servo land where it lands, then screw it down into the rail.

They're MUCH happier now.
 

TexMechsRobot

Posted a thousand or more times
Tench745 said:
I believe the problem you're running into is not how well the covering sticks to nylon, but the thermo-elastic properties of the nylon. IE, your nylon expands when you stick the covering on with heat, then contracts as it cools, wrinkling your covering. If this is, in fact, the case I doubt applying bondo or fiberglass to the surface will help much. The nylon will just expand and contract under your filler material and crack that too.
I think the safest bet is to remove the covering, sand the nose smooth, and paint it. Doing it in a complementary color like rockyboy suggested would probably look best.

Alternatively, if you can get the iron really hot and stick your covering down as quickly as possible (fast-fast) the underlying surface might not heat up enough to cause the troublesome expansion. Maybe do a small section at a time and let it cool in between.
This was exactly my concern. I figured the nylon shrinking as it cooled was my issue and that the thin layer of anything I put over it wouldn't fix the problem. I may try to do the spot method you mentioned before I pull it all off since it can't hurt to try. I've pretty much resolved to pull it off and paint it though since it seems like the only thing that'll really get the job done properly.


Craftydan said:
Ran into the same trouble with linkages. started off with low-end 9g tower pro's, with a touch more bend than they liked . . . No dice. would struggle to move at all and couldn't center.

Swapped out a beefier servo (MG-92B), switched to a open-sided tandem setup, then let the servo find it's own happy spot along the width:

Attachment 87750

it's only by chance they're both so close to centerline. you let the servo land where it lands, then screw it down into the rail.
There isn't much bend in the area near the servo. Most of the bend is at the tail where it curves to exit the fuselage and connect to the rudder. I went to the LHS last night to pick up some items and wandered around for 15 minutes because I had 5 items in my hand and I knew there were 6 items on my list (that I forgot to bring with me). I left without the smaller pushrod that I needed to test that theory....

I did discover that a 9/32" rod is too big to fit in the carbon arrow shaft. I wrapped one layer of masking tape around the 1/4" joiner rod and it was a perfect fit.

I didn't get any work done on it last night because we were packing to go camping and I'll be gone all day Saturday and Sunday morning. I'm headed over to a Pacific Northwest event called "6 Pack" that is all about sloping. I'm going to hope for light winds so I can try out my Alula Trek and then watch the big boys play with their half-piping 300mph monsters.
 

nhk750

Aviation Enthusiast
I was just thinking about rubber bands. My Trainstar Exchange has these nice white, longer than #64, rubber bands it came with and they are really nice. You can Google Trainstar Exchange and actually order these rubber bands. I like them as they are just a little longer than the #64 rubber bands and they seem much more durable too.
 

TexMechsRobot

Posted a thousand or more times
After a weekend at 6Pack in Eastern Washington (Eagle Butte, Sam's Dirt Ridge, Kionna Butte) watching the big boys play with their slope planes, I got home Sunday morning and made a lot of progress finishing out the nose and covering the wings. I tried to heat zap the covering on the nose by applying a very hot iron to small sections of the nose for about 1-2 seconds. It was enough to shrink the covering and not heat up the nylon too much. But the effort was going to take a couple of hours and I didn't want to wait so I masked the area off, cut the covering back, and painted it white. I painted the spinner red with the idea that it would be easily identifiable when landing but the now I think it looks like a clown and I may sand it of and go with white. My wife says it looks fine lol.

1.jpg

2.jpg

I went really simple on the wings. Just solid black on the bottom and white with red tips on the top.

3.jpg

4.jpg

I'm really close to a maiden once I get the electronics sorted out and an initial balance. I'm thinking I should be tossing this in about 2 weeks.

5.jpg
 

TexMechsRobot

Posted a thousand or more times
I gave it a quick balance last night by loosely placing the battery and ESC on top of the hatch as I balanced it. I should be able to balance it effectively without adding any unnecessary weight. It seems to be pretty touchy to the weight change though. If I shifted the battery 1/8" in either direction, it tipped beyond balance and wanted to fall off of the balance sticks. I hope it isn't that sensitive in flight. I'll know more once I can give it a few glide tosses.

I also did an AUW measurement and it came in at just under 65 oz which I am happy with. I'll add a few grams with velcro, a battery stop block, and some glue but I should easily stay under 70 oz which was my goal. That puts me at about 9 oz/sqft wing loading.

Tonight I plan to install the electronics and harnesses and do another balance test. I plan to start my balance at 40% chord and adjust from there. Craftydan, where do you like yours balanced?
 

nhk750

Aviation Enthusiast
That wing is beautiful! Can you gee a picture of it on the balance sticks? I am curious how it looks and your balance stick system too. Thanks.
 

TexMechsRobot

Posted a thousand or more times
Thanks! I'll try to remember to take pictures when I balance it.

The "balance stick system" is a 2x4 with 1/4" holes drilled in it and 1/4" dowels with a glob of hot glue on the end to soften the tip. Nothing fancy.
 

TexMechsRobot

Posted a thousand or more times
I got the electronics placed and velcro installed and then the weight and balance refigured. I'm sure it'll take a few tweaks and corrections as I do the glide tests but it's good for now.

1.JPG

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3.JPG

My next step was to program the radio and this part stumped me. Maybe you guys can help. Here's a picture of how I plan to plug in the different parts. I have a DX9 radio.

4.JPG

AUX1 has the ESC (not connected in this image)
GEAR has the left wing spoiler
RUDD has the right wing spoiler
ELEV has the elevator
AILE has the rudder

What I want:

The AUX1 to be programmed to a switch so that the motor is on or off.
The GEAR and the RUDD to be programmed to the throttle stick so that I can control them with a high degree of precision and trim them separately.
The ELEV and AILE are easy and I've got those figured out.

Help?
 
Um... you could probably mix things to make that happen, but, why?
The easy way, to my mind, would be to put the spoilers on AUX and GEAR and the ESC into throttle. You could program the spoilers on the rear sliders if you wanted to control them separately. I don't know enough about the DX9 to tell you how though.
 

TexMechsRobot

Posted a thousand or more times
I could but the rear sliders aren't comfortable to control at the same time while also trying to land with rudder and elevator. Also, I want fine control of the spoilers and I won't need fine control on the throttle. I could feasibly move the servos to different ports on the RX but that's beside the point. I don't know how to program the radio to different ports on the RX. I'm pretty sure I want to do it the way I described and just need help with letting the radio know.
 

nhk750

Aviation Enthusiast
Thanks for the pics! It looks great. I'm going to make a balancer like yours too. I'm getting pretty good with programing the DX8G2, but I will need to think about what your trying to do when I am more awake. I do know that you can do just about anything with the DX8-20 radios, they are good for that.
 

TexMechsRobot

Posted a thousand or more times
I didn't realize this until last night: I'm basically done except programming the radio and the maiden.

I can't seem to figure out how to program the freaking transmitter. Apparently, plugging the ESC into any port except the throttle on the RX is a no-no in order to ensure the failsafe works. I realized I don't even know what failsafe is or does. I'm so at a loss right now it feels alien to me. I've never been this slow on the uptake of new technology (new to me!) and it really feels weird. I won't have time to mess with it until Sunday or Monday but we'll see where the next attempt takes me.
 

nhk750

Aviation Enthusiast
I believe your correct, the esc has to be in port #1, throttle. But, you can create mixes and also different flight modes so can can assign switches on the tx to do almost anything you can imagine. The problem I have been running into is that there are not very detailed instructions on how to do this written by Spektrum. Someone out there probably has a detailed guide, but we just need to find it. I have experimented with some stuff and I just havnt had time to get into it any further lately as I got what I needed to work and stopped there. I have read that guys can create mixes and flight modes for knife edge, hovering, glider modes, ect, so its just a matter of finding a better instruction for the tx.
 

TexMechsRobot

Posted a thousand or more times
Yep. I read all over the place things like "just bind the throttle stick to one spoiler and mix the other" but I have no idea HOW to do that lol. I don't really need theory just yet, I need practical steps to follow and then I can try to understand the theory. I can't find steps anywhere.
 

Craftydan

Hostage Taker of Quads
Moderator
Mentor
Hey Tex!

She's a beauty. Only thing that will make her prettier is blue sky around her ;)

As for CG, I've set mine to the "nonminal" position which is just a hair aft of the spar. It can go back farther . . . but for maiden, I'd recommend a touch more forward -- middle of the spar and work it back to your taste. On mine, "nominal" feels fairly close to neutral, and the aft position is known to be tail heavy. Most of what I've seen online says the leading edge of the spar is still safe, so middle of the spar should be a good place to start.

As for failsafe . . . that exists entirely in the RX. When it looses signal, it's the backup plan it uses. There are a few brands that the failsafe can be adjusted through the radio, but for DSM RX's it's done either through the bind process or not at all(some RXs don't have a failsafe). power the plane down, plug in the bind plug, power up the radio, hold the channel positions you desire (throttle down, spoilers extended, rudder ~1/3, and elevator adjusted to encorage a somewhat downward spiral). power up the plane, and if all works well the RX will remember the positions. Pull the bind plug and power down the TX to verify.

a few caveats:

- Failsafe sometimes only works for the first 4 flight channels. some do, some don't. if your spoilers are mapped to an Aux channel, it may not respond.

- Some RX's have a fixed fialsafe (throttle to 0, all else to middle), Some retain the last position (IIRC, none of the DSM RX's do that) and some don't have ANY failsafe (signals simply stop). In either case, most ESCs will simply stop, and in the second case the servos may go limp.

I'd advise running a range check (as always) and then maidening *WITHOUT* setting the failsafe. get a feel for her at lower altitudes, and when you get a chance (and before you go hunting for that boomer) find a sweet-spot in the controls that will throw her into a somewhat flat spiral. This is what you'll set your failsafe to. Set that, and go find that boomer ;)


As for Programming . . . Id recommend sticking to TAER order with a few adjustments -- connect the rudder to aileron (so it flies off one stick) and plug one spoiler to the rudder channel (so it can respond to a failsafe) and the other to AUX1 (I've servo Y-ed mine together, but that makes sub-trim unavailable) . . . then we'll play with the mixing.

- Mix -100% Rudder -> Rudder (always on), so the rudder Stick will be canceled by itself in the rudder channel output (4th channel). once this is on, moving the rudder stick will have no effect on the monitor page.

- Mix a chosen "spoiler" switch -> rudder (always on). Adjust the % amount and offset to set them to the open and closed positions -- you can adjust a mid position through setting up a curve, if you care to.

- Mix the spoiler switch -> AXU1 adjusted like the last mix so the two spoiler channels follow each other. Keep in mind, once spoilers break the laminar flow, their affect is practically "on" or "off" -- unlike flaps, there isn't much to feathering them out.

You should now have throttle/nothing on the left stick, spoilers on a switch, elevator/rudder on the right stick.

If you want to put throttle on a switch, create a mix+switch mapping like you did for the spoiler switch.


So finish setting her up and find a nice blue patch of sky to frame her in ;)