The Sprat - A new year's build
- Thread starter speedbirdted
- Start date
Tench745
Master member
Looks to me like the second section forward of the stab was patched. The tissue is a little more opaque on the longerons than the others.
Also, a second on that tail jig being pretty clever. That's getting stored away in the memory banks for later use.
TooJung2Die
Master member
Bingo! Give that man a cigar. 😄 I agree, the tail jig idea is a winner.
speedbirdted
Legendary member
Ain't it funny how a tail jig that I spent one minute making is garnering more attention than the airplane that's the actual subject of the thread? 
At least I still remember how to secure things with thread and CA. It's been a while. I had no sections of wire long enough to make the gear out of a single piece so I just used two. Not gonna make much of a difference anyway. I probably could have shortened the gear by a couple inches. It's only the length it is to let the prop clear the ground under rubber power. But I kinda like the silly long legged look...
Also painted the interior a bit, just to match the tissue. I made no attempt to paint any gauges on the dash. No pilot will be installed so there's not really a need for them.
I also made some test windshields out of paper just to see if it would look better than doculam or something. The contour actually looks pretty good so I think I'll make a windshield from .003 cellophane or something of that nature.
Next step was making some tires out of foam. After several failed attempts to secure foam to a dowel with various adhesives from around my house I gave up and went to the store to buy foam safe CA... to find none in stock. Guess I get to wait for that now too...
At least I still remember how to secure things with thread and CA. It's been a while. I had no sections of wire long enough to make the gear out of a single piece so I just used two. Not gonna make much of a difference anyway. I probably could have shortened the gear by a couple inches. It's only the length it is to let the prop clear the ground under rubber power. But I kinda like the silly long legged look...
Also painted the interior a bit, just to match the tissue. I made no attempt to paint any gauges on the dash. No pilot will be installed so there's not really a need for them.
I also made some test windshields out of paper just to see if it would look better than doculam or something. The contour actually looks pretty good so I think I'll make a windshield from .003 cellophane or something of that nature.
Next step was making some tires out of foam. After several failed attempts to secure foam to a dowel with various adhesives from around my house I gave up and went to the store to buy foam safe CA... to find none in stock.
Guess I get to wait for that now too...
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TooJung2Die
Master member
I thought for sure you'd turn some wheels using laminated balsa. Now I'm interested to see your foam wheels idea.
Born2bwire
Member
Like TooJung2Die, I find that it's easier to do the tips as a separate pieces. What it allows you to do is to pull the wingtip's tissue back towards the wing root, which helps get rid of the puckering you have at the rib and trailing edge. While the tissue is damp, I'll keep running my thumb down across the lip of the wingtip as the adhesive tacks and dries to work out the wrinkles. It's probably different working with the glue stick, but it keeps pulling the tissue taut and sticking while I work to pull the wrinkles out in different directions.Yeah, a pair of 9g servos would be nearly half the AUW
After attempting to use the tape method to hold the v/h stabs together to glue them and have it fail horribly I got lazy and made this jig to hold them together so I could do something else while the glue dried. If it looks stupid but it works it isn't stupid...
View attachment 189061
I also got the wing covered. This was significantly less pretty than the tail covering but I guess it's still passable for the first full wing I've ever covered in tissue. The wingtips put up a bit of fuss. I sprayed it with water to try and get it to stretch a little but it didn't seem to really stretch at all. It didn't become weak, it just wouldn't stretch. Maybe I wasn't getting it wet enough. A light misting is all I really gave it.
View attachment 189064
You know what I did immediately after finishing the wing?
I dropped it.
View attachment 189065
So I guess I now get to test my ability to patch holes in tissue as well. I'm thinking I will cut all the tissue from the bay the tear is in and then glue down the edges before adding new tissue on top of it. Or I could just put tissue immediately over the tear, like how you'd apply a second layer of tissue. Help is appreciated...
For the tear, I would cut out the bay and recover along the perimeter of the spar, ribs and leading edge. For the patch, it's best if you don't cut it with scissors but using sandpaper. This will feather the edge and make the seam disappear.
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speedbirdted
Legendary member
Too heavy
By comparison the wheels I made for the Q-tee weighed about 2.5g apiece. 5g here is 10% of the total AUW!The technique was pretty much the same though. Admitting defeat in finding another suitable glue I just mixed up some epoxy (wasting 90% of it) and secured the dowels with that. Then I turned them to shape in the drill press. Here they are pre-finishing. One is sanded round while the other is still rough.
I managed to make one good tire and totally messed up the second one, then proceeded to go through about 6 other tires trying to make an identical one
The treading is hard to match up. I got the shape right every time but I would always put on either the wrong amount of treads or they would be mis-spaced or something. In retrospect it's a tiny tire and I doubt anyone would ever see if one had 6 treads and the other 7, but I guess my OCD takes over sometimes...I coated them in acrylic paint. Looks good. I would normally be concerned about the paint flaking off but 95% of the surface this tire touches will probably be smooth gym floor so I doubt that will be much of an issue.
And, a rude awakening to the reality that I really have no idea what I'm doing when it comes to tissue
The blue tissue is quite hardy, but the white tissue just really isn't. In retrospect I might have piled on the dope too much and overshrank it, which is weird because you can still see there are wrinkles in it. This side is full of little splits and holes like this but there are one or two bays which are okay. The other side is pretty much a total loss and it'll get stripped and redone. I really hope I didn't put on so much dope that I can't get it off with ethyl alcohol.
TooJung2Die
Master member
Sorry to see what happened with the white tissue. I had plenty of "tissue issues" when I was covering the One Nite 28 if that's any consolation. The tissue should have some wet strength or it tears when shrinking. I found a lot of the tissue that comes in kits is no good. I can't remember how many times I stripped and recovered it until I was satisfied. I was much better at it when it was finally done.
I’ve never worked with plane tissue before, what is it like? Is it like facial tissue, a paper roll, or what in terms of toughness?Too heavy
The technique was pretty much the same though. Admitting defeat in finding another suitable glue I just mixed up some epoxy (wasting 90% of it) and secured the dowels with that. Then I turned them to shape in the drill press. Here they are pre-finishing. One is sanded round while the other is still rough.
View attachment 189266
I managed to make one good tire and totally messed up the second one, then proceeded to go through about 6 other tires trying to make an identical one
I coated them in acrylic paint. Looks good. I would normally be concerned about the paint flaking off but 95% of the surface this tire touches will probably be smooth gym floor so I doubt that will be much of an issue.
View attachment 189267
And, a rude awakening to the reality that I really have no idea what I'm doing when it comes to tissue
View attachment 189268
Matthewdupreez
Legendary member
speedbirdted
Legendary member
I didn't expect everything to be perfect. Usually the first airplane you cover in a new material ends up being redone at some point. It's strange though, as the vertical and rudder were covered in the exact same tissue and it went down fine there. No issues with splitting at all. I think it was from a different sheet though, while still in the same bundle of tissue... maybe there was just a dud sheet stuck in there.
I remember when I brushed the little overhangs down at the edges of the fuselage, it was splitting and tearing even there as soon as the dope hit it. An omen for bad things to come that I missed.
speedbirdted
Legendary member
Took the time today to get rid of the old tissue. Luckily a quick misting of ethyl alcohol was all I needed. The glue surrendered pretty fast and the tissue came right up.
Second attempt I was much more conservative with the dope and it went a bit better. After the initial coat dried there were a few more spots that still had a wrinkle or two but a little more dope brushed there was all it took to get rid of them. The stripe wasn't my idea. A friend came by the shop and suggested the fueslage looked too bare without it and I agreed with him. I covered all sides except the top, and it will go on once I get the pushrods routed.
The turtle deck at the front was the most fuss here. I went through 3 or 4 pieces of tissue trying to get one that lined up with the sticks coming off the dashboard well. Compound curves are just really annoying to do with tissue I guess. It's a little frustrating seeing a section that a contemporary plastic film would make quick work of put up so many problems with tissue.
It might seem like I've built enough wheels at this point but no I had to build more after realizing having a wooden dowel as a hub wasn't going to work as well as I wanted. I also had a piece of plastic pushrod sheath that fit over the landing gear legs perfectly and was just begging to be used as a bearing.
After some practice I managed to get two mostly identical wheels mounted to wires slightly less diameter than the plastic sheath so they'd fit nice and snug. I did this only with them in a dremel. Compared to the drill press the range of motion available is so much nicer.
After mounting and paint. The size is a little bit goofy looking with the length of the gear but this is no scale ship so I'm not concerned about it.
Second attempt I was much more conservative with the dope and it went a bit better. After the initial coat dried there were a few more spots that still had a wrinkle or two but a little more dope brushed there was all it took to get rid of them. The stripe wasn't my idea. A friend came by the shop and suggested the fueslage looked too bare without it and I agreed with him.
I covered all sides except the top, and it will go on once I get the pushrods routed. The turtle deck at the front was the most fuss here. I went through 3 or 4 pieces of tissue trying to get one that lined up with the sticks coming off the dashboard well. Compound curves are just really annoying to do with tissue I guess. It's a little frustrating seeing a section that a contemporary plastic film would make quick work of put up so many problems with tissue.
It might seem like I've built enough wheels at this point but no
I had to build more after realizing having a wooden dowel as a hub wasn't going to work as well as I wanted. I also had a piece of plastic pushrod sheath that fit over the landing gear legs perfectly and was just begging to be used as a bearing. After some practice I managed to get two mostly identical wheels mounted to wires slightly less diameter than the plastic sheath so they'd fit nice and snug. I did this only with them in a dremel. Compared to the drill press the range of motion available is so much nicer.
After mounting and paint. The size is a little bit goofy looking with the length of the gear but this is no scale ship so I'm not concerned about it.
TooJung2Die
Master member
Your foam wheels look great. I'm going to have to try making some of those. I think I gave up the last time I tried because I couldn't get the foam stuck to the dowel and it kept tearing off. I don't think I tried epoxy. I think the fuselage looks great and the blue lightning bolt was a good idea. The only person that is going to notice a little wrinkle is you! Everyone else will be gobsmacked by the tissue covering. 😁
speedbirdted
Legendary member
No need to waste epoxy! I bought a bottle of this stuff and it works perfectly even if it takes forever to cure. It will hold parts in place after an hour or two but you need to let it sit overnight before it's strong enough to shape a wheel with it.
TooJung2Die
Master member
I have Foam-Cure. Good stuff. It doesn't expand all over the place like Gorilla glue. I got some so I can build using EPP foam. I also have Smith's foam safe CA. I probably chose the wrong kind of foam. It has to be flexible but you have to be able to shape it with sandpaper.
Those wheels look great! What type of foam are they made out of?Took the time today to get rid of the old tissue. Luckily a quick misting of ethyl alcohol was all I needed. The glue surrendered pretty fast and the tissue came right up.
Second attempt I was much more conservative with the dope and it went a bit better. After the initial coat dried there were a few more spots that still had a wrinkle or two but a little more dope brushed there was all it took to get rid of them. The stripe wasn't my idea. A friend came by the shop and suggested the fueslage looked too bare without it and I agreed with him.
The turtle deck at the front was the most fuss here. I went through 3 or 4 pieces of tissue trying to get one that lined up with the sticks coming off the dashboard well. Compound curves are just really annoying to do with tissue I guess. It's a little frustrating seeing a section that a contemporary plastic film would make quick work of put up so many problems with tissue.
View attachment 189341
It might seem like I've built enough wheels at this point but no
After some practice I managed to get two mostly identical wheels mounted to wires slightly less diameter than the plastic sheath so they'd fit nice and snug. I did this only with them in a dremel. Compared to the drill press the range of motion available is so much nicer.
View attachment 189342
After mounting and paint. The size is a little bit goofy looking with the length of the gear but this is no scale ship so I'm not concerned about it.
View attachment 189343
speedbirdted
Legendary member
Dunno really. It's the green stuff that tends to get used as insulation in houses...
Windshield and related items went on today. The windshield actually went on about four separate times because the glue was deciding not to behave. The fit is good though. The side windows were glued separately as the front rubber band peg meant I couldn't do it all as one piece of plastic like I wanted. But, had I done it that way, and installed the peg after adding the windshield, I probably would have gotten CA all over it and fogged it to hell.
I also glued the tail on which was a pretty simple task, just had to get it sitting on there straight. The final pieces of tissue were also applied to the fuselage, and the pushrods were routed.
And now this project will sit for a while. As it turns out, the actuators in the board I was going to use have some pretty severe problems. One of them functions sort of okay, but the other freezes up as soon as any load is applied to it, no matter how small. It's a weird way for it to not work - it freezes in place as soon as you put any load on it and won't move even if the load is removed and then you jiggle the stick around, causing it to make weird noises and the little motor in there gets incredibly hot and starts smoking. I disassembled both actuators trying to find what's causing this weird behavior but it has me stumped. Another board is only like 25 bucks, but they all come from China which takes forever (and I'm not even sure if it would work any better in that case...)
One of these might work, and they ship from the US:
https://www.backcountryrc.com/product-page/5ch-micro-servo-esc-brick
