I like the magnet kit that is sold to help hold everything together. It's cheap insurance against having a wing panel fall off!
Bird of Time Balsa Kit Build Thread
- Thread starter TexMechsRobot
- Start date
You'll never have a problem with the friction-fit stabilizer. The more it is tugged on from the air, the more friction the rod-in-tube will produce, holding it in place. It should slide directly into the mount without much force, but the aerodynamic forces it's designed for will hold it in place. A slight bend in the rod will be more than enough.
BTW, Dave Thornberg (the designer) recommends bending the elevator join rods slightly downward, so while in flight they'll flex up to square. IIRC his comment was for aesthetics, though -- he tended to be on the "if it looks nice it'll fly nice" side of things. Hard to disagree with him on that.
The wing mounts, though . . . Magnets are cute and will help hold it together . . . while you're taping the wings together.
Seriously.
Don't trust a friction fit on the main wing. Particularly a 3m main wing.
After you've covered the wings, wrap the end of each wing join with a single layer of packing tape to protect the covering. Then, when it's time to fly, mechanically join the wing, then tape the wings together using Electrician's tape (it's a good vinyl tape that holds well with just a smidge of stretch).
To tape, I use an "I" pattern -- put a strip on the LE across the join, a strip on the TE (both narrower than the packing tape -- don't want to pull up the covering), then one wrap around the join.
BTW, Dave Thornberg (the designer) recommends bending the elevator join rods slightly downward, so while in flight they'll flex up to square. IIRC his comment was for aesthetics, though -- he tended to be on the "if it looks nice it'll fly nice" side of things. Hard to disagree with him on that.
The wing mounts, though . . . Magnets are cute and will help hold it together . . . while you're taping the wings together.
Seriously.
Don't trust a friction fit on the main wing. Particularly a 3m main wing.
After you've covered the wings, wrap the end of each wing join with a single layer of packing tape to protect the covering. Then, when it's time to fly, mechanically join the wing, then tape the wings together using Electrician's tape (it's a good vinyl tape that holds well with just a smidge of stretch).
To tape, I use an "I" pattern -- put a strip on the LE across the join, a strip on the TE (both narrower than the packing tape -- don't want to pull up the covering), then one wrap around the join.
TexMechsRobot
Posted a thousand or more times
The magnet kit is designed for the ARF wing which is 3 panels. The balsa kit is actually just cut in half in the middle and the magnets provided by RCAirMods.com would work right with Pugh some extra modification. I had planned to use Craftydan's suggestion anyway so it's nice to have the method confirmed.
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TexMechsRobot
Posted a thousand or more times
Good idea on the stabilizer friction fit.
TexMechsRobot
Posted a thousand or more times
I graduated this past weekend so I didn't have much time to build with all the travelling. But I took Monday off of work and spent the day on the Bird of Time and made a lot of progress. Most of the work was in trying to smooth out the body lines. I tried to shave as much of the unnecessary balsa as possible to get that clean, oval cross section and to shave off weight. I didn't want to risk going too thin though so there is probably a little more balsa left than necessary. I also finalized the pushrods, floated in the nose with bondo, and built the nose hatch. I tried a thing to get the bondo to contour to the wing for airflow purposes and it worked out pretty well. I also covered the tail surfaces using Neucover and I have to say, I like the stuff. It was much easier to work with it over the Monokote. I'm a little nervous about the large balsa surfaces on the fuselage so we'll see how that goes this evening.
TexMechsRobot
Posted a thousand or more times
Dubro pinned hinges. I don't like using CA hinges. They seem too stiff to me.
TexMechsRobot
Posted a thousand or more times
After much thought and research, I am going to use the rubber band method for holding on the wings.
Has anyone done this with the Bird of Time or something similar? I'm concerned that the standard #64 size won't be big enough to span the cord without breaking. Is there another size that would work better?
Has anyone done this with the Bird of Time or something similar? I'm concerned that the standard #64 size won't be big enough to span the cord without breaking. Is there another size that would work better?
It's on the long side for #64's but that's what I use. They hold fine and snap if the wing touches the ground on landing. Longer may survive a wing-tip-strike better . . . but I count these bands as disposable.
You'll want several (I usually use 4-6) and you'll want to re-enforce the TE to keep them from crushing the wing or slipping into the gap (2-piece -- 3 piece doesn't have a gap).
You'll want several (I usually use 4-6) and you'll want to re-enforce the TE to keep them from crushing the wing or slipping into the gap (2-piece -- 3 piece doesn't have a gap).
TexMechsRobot
Posted a thousand or more times
Thanks! How did you reinforce? I already plan to hide the seam with the tape method you described. Should I laminate a thin ply piece to the TE corner of each wing?
I haven't quite found a solution that I like. Between the heavy balsa TE, covering and tape it's holding together, but I'm not happy with it.
My next approach is slipping in a bit of thin carbon plate into the corners, possibly with a lip on one edge to keep the bands off-center, but I've got a few other things on my bench ahead of it.
My next approach is slipping in a bit of thin carbon plate into the corners, possibly with a lip on one edge to keep the bands off-center, but I've got a few other things on my bench ahead of it.
TexMechsRobot
Posted a thousand or more times
I tested some #64 rubber bands and they seem to do the trick nicely. I'm going to buy a bag of black ones since they'll match the scheme a little better than the beige standard.
While the wing was strapped on, I tested the fit by holding the fuselage in my hand and bouncing the whole plane up and down about 3-5 inches to simulate turbulence. The wings flexed a little as expected and the rubber held without trouble. However, I could hear the joining 1/4" steel rod rattling around in the arrow shaft slots pretty badly. I knew it was a loose fit but I wasn't sure how loose until now. It was so loose that I could easily imagine stress pressure points forming at the tips and middle of the bar instead of the weight being evenly distributed across the whole bar. I took it apart and measured the parts. The steel bar is .250" and the ID of the arrow shaft that came with the kit is about .290".
I have several options for a solution.
Any thoughts on the above? Any options I left out that are better? Apparently, this is a known problem with the kit. If I had known better from the start or if I ever do it again, I'll just find a tube that's the right size to start with and use that instead of the supplied arrow shaft.
I got a little more covered on the fuselage including the hatch cover. I only have the nose area left. The curves there will be a slight challenge but no worse than any of the rest really.
While the wing was strapped on, I tested the fit by holding the fuselage in my hand and bouncing the whole plane up and down about 3-5 inches to simulate turbulence. The wings flexed a little as expected and the rubber held without trouble. However, I could hear the joining 1/4" steel rod rattling around in the arrow shaft slots pretty badly. I knew it was a loose fit but I wasn't sure how loose until now. It was so loose that I could easily imagine stress pressure points forming at the tips and middle of the bar instead of the weight being evenly distributed across the whole bar. I took it apart and measured the parts. The steel bar is .250" and the ID of the arrow shaft that came with the kit is about .290".
I have several options for a solution.
1. I can wrap the whole bar in something about .020" thick to take up the extra space. I'm thinking fiberglass or tape would be easy enough to manage.
2. I can epoxy it into one half of the wing and wrap the other half.
3. I can try to fill the arrow shaft with something hard and re-drill it to the correct dimension. This seems like a terrible idea.
4. I can buy a brass/aluminum tube with thin wall that will slot in and fill the space. (link to such a rod)
5. I can buy a 9/32" steel rod. They are much harder to come by than you might think.
2. I can epoxy it into one half of the wing and wrap the other half.
3. I can try to fill the arrow shaft with something hard and re-drill it to the correct dimension. This seems like a terrible idea.
4. I can buy a brass/aluminum tube with thin wall that will slot in and fill the space. (link to such a rod)
5. I can buy a 9/32" steel rod. They are much harder to come by than you might think.
Any thoughts on the above? Any options I left out that are better? Apparently, this is a known problem with the kit. If I had known better from the start or if I ever do it again, I'll just find a tube that's the right size to start with and use that instead of the supplied arrow shaft.
I got a little more covered on the fuselage including the hatch cover. I only have the nose area left. The curves there will be a slight challenge but no worse than any of the rest really.
I would try wrapping the arrow shaft with a little teflon plumbers' wrap about a 1/3 in from the ends and again on either side of the middle join point. A drop of CA will keep the teflon from unraveling, and it should help cushion against any rattles. I've used this method for guitar truss rods with good success.
It might not be easy to find, but if you can, I'd go with the thicker steel joiner. 1/4" works, but is a bit on the skimpy side. an extra 1/32" may not be much, but you'll actually pick up needed strength from it where the tape will compress under load.
If you use the 1/4 bar you could put a layer or 2 of heat shrink tubing on it.
TexMechsRobot
Posted a thousand or more times
I made some progress and ran into a couple of problems. Progress first.
I built and installed the servo tray with linkage stoppers.
Now for the problems.
After installing the servos, I attached the cable for the elevator without issue. I'll have to tweak the position later but it fit nicely. Then I fed the .060" pushrod for the rudder and it seemed a really tight fit in the pushrod guide. During construction, I opted to install a full length guide that had an ID of about .065" in order to allow me to install the actual pushrod after covering. I realized that this would add excess weight in the tail but I am confident that this will be offset by the motor and battery (I still think this is the case). However, having that much friction for about 20" with a gentle curve provides more resistance than I expected. I added a small amount of oil into the pushrod guide and it seems to have helped a little but not enough. The servo is an HS85MG so it can probably handle it but I don't want make it. I plan to buy a thinner piano wire this evening and test it out to see if I get better results.
Second problem and this is the big one.
Apparently, Neucover doesn't really stick to nylon. I finished covering the nose yesterday and it looks terrible. The covering will shrink when heat is applied and it looks great. But as soon as it all cools down (the nylon nose is a pretty good heat sink so it holds the heat), the covering will wrinkle up. I've punched a bunch of holes in the covering and applied the heat and that didn't help at all.
Again, I have several options.
1. Leave it alone. Besides the terrible looks up close (it looks fine at 500'), I don't think it's going anywhere. The risk of it coming off in flight is pretty low and even if it did, it's fastened really well where it meets the balsa and at worst, it would just cause a bit of drag but would not cause a catastrophic failure. However, the modeler in me hates it.
2. Pull it off, cover the nylon in a thin layer of bondo to even the surface, and cover it again. There is no guarantee that this would help since the bondo would be super thin.
3. Pull it off, bondo the nose to get an even surface, and paint it. It wouldn't be a perfect match to the covering.
4. Some other option I haven't thought of.
I built and installed the servo tray with linkage stoppers.
Now for the problems.
After installing the servos, I attached the cable for the elevator without issue. I'll have to tweak the position later but it fit nicely. Then I fed the .060" pushrod for the rudder and it seemed a really tight fit in the pushrod guide. During construction, I opted to install a full length guide that had an ID of about .065" in order to allow me to install the actual pushrod after covering. I realized that this would add excess weight in the tail but I am confident that this will be offset by the motor and battery (I still think this is the case). However, having that much friction for about 20" with a gentle curve provides more resistance than I expected. I added a small amount of oil into the pushrod guide and it seems to have helped a little but not enough. The servo is an HS85MG so it can probably handle it but I don't want make it. I plan to buy a thinner piano wire this evening and test it out to see if I get better results.
Second problem and this is the big one.
Apparently, Neucover doesn't really stick to nylon. I finished covering the nose yesterday and it looks terrible. The covering will shrink when heat is applied and it looks great. But as soon as it all cools down (the nylon nose is a pretty good heat sink so it holds the heat), the covering will wrinkle up. I've punched a bunch of holes in the covering and applied the heat and that didn't help at all.
Again, I have several options.
1. Leave it alone. Besides the terrible looks up close (it looks fine at 500'), I don't think it's going anywhere. The risk of it coming off in flight is pretty low and even if it did, it's fastened really well where it meets the balsa and at worst, it would just cause a bit of drag but would not cause a catastrophic failure. However, the modeler in me hates it.
2. Pull it off, cover the nylon in a thin layer of bondo to even the surface, and cover it again. There is no guarantee that this would help since the bondo would be super thin.
3. Pull it off, bondo the nose to get an even surface, and paint it. It wouldn't be a perfect match to the covering.
4. Some other option I haven't thought of.
TexMechsRobot
Posted a thousand or more times
I just thought of a 4th option. Pull the covering off, lay 1/2 oz fiberglass with epoxy over the nylon, then cover with the Neucover. That's assuming that they epoxy and fiberglass adhere to the nylon without too much trouble. There are a few compound curves that scare me. I actually do have a spare part made from the nylon that I can practice on.
Tench745
Master member
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.
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.
