Frog Junior Sailplane scratchbuild

[speedbirdted]

Doing this for a friend. He wants to try a tissue paper covering job, but is quite pushed for time by work and other projects to build it himself. So, he passed it off to me. This whole quarantine thing has me absolutely stuffed with free time, so I of course was happy to...

Here's what I'm working with. I'll be making a couple changes right off the bat, mostly for RC control. He gave me a little UMX board to work with, and turned sideways it does fit. Also, nowhere local to me sells balsa sheet light enough to make a tail out of, so I'm going to be drawing up my own plan for stick building it.

Speaking of the balsa. My LHS' balsa selection is usually crap. So bad in fact that the minimum-wage employee in charge of restocking the balsa selection restocked it with... basswood. All of it. So no use there either. But I've got a trick up my sleeve called a balsa stripper! And I've got some sheets of 3/32 balsa that's not quite contest grade but it's darn good. All the sticks used in this build have at least one dimension of 3/32, so this should be pretty easy.

All I have done for now is the fuselage sides, which went together easily (and I also which I stupidly forgot to take a picture of before I went to work, oops) Honestly if you need a balsa stripper, just build your own. It's what I did and it hasn't let me down so far.

This is gonna be a really fast build, since I have no covering to do. But, I'll send pictures of it when the other guy does his part of the build

 

[TooJung2Die]

Honestly if you need a balsa stripper, just build your own. It's what I did and it hasn't let me down so far.

Nice joint project. Looking forward to the build. How about a closeup of your stripper so we can see how it is constructed? I like DIY and improvising.

 

[OliverW]

Doing this for a friend. He wants to try a tissue paper covering job, but is quite pushed for time by work and other projects to build it himself. So, he passed it off to me. This whole quarantine thing has me absolutely stuffed with free time, so I of course was happy to...

Here's what I'm working with. I'll be making a couple changes right off the bat, mostly for RC control. He gave me a little UMX board to work with, and turned sideways it does fit. Also, nowhere local to me sells balsa sheet light enough to make a tail out of, so I'm going to be drawing up my own plan for stick building it.

Speaking of the balsa. My LHS' balsa selection is usually crap. So bad in fact that the minimum-wage employee in charge of restocking the balsa selection restocked it with... basswood. All of it. So no use there either. But I've got a trick up my sleeve called a balsa stripper! And I've got some sheets of 3/32 balsa that's not quite contest grade but it's darn good. All the sticks used in this build have at least one dimension of 3/32, so this should be pretty easy.

View attachment 177323

All I have done for now is the fuselage sides, which went together easily (and I also which I stupidly forgot to take a picture of before I went to work, oops) Honestly if you need a balsa stripper, just build your own. It's what I did and it hasn't let me down so far.

This is gonna be a really fast build, since I have no covering to do. But, I'll send pictures of it when the other guy does his part of the build

@Paracodespoder made one of these if memory serves. I'm a bit slow so that doesn't help

 

[speedbirdted]

Nice joint project. Looking forward to the build. How about a closeup of your stripper so we can see how it is constructed? I like DIY and improvising.

Far from pretty, but she does the job. Just made of 1/8 inch ply. I had a stripper from Master Airscrew, what a hunk of junk! I'm going to build another slider for this one with the ability to rotate the blade to make bevel cuts in things.

As for the plane itself, the fuselage is coming along. Cut out all the formers, well, except the last one - it seems to have been left out of the plan, but that's understandable as I'm pretty sure it was originally sold kitted by somebody... but why in that case would they have all the others? Anyway I'm gonna kinda interpolate what it should be like and cut it out. The piece in the middle in between the two formers is where the board goes onto. I still have the nose cone and the longerons on top to do, but that's easy enough.

The guy that's gonna get this airplane told me that I can just leave the front open. Normally it gets covered with a little piece of plastic or something but he said he wants to leave it and install a pilot figure. I think that'll look cool...

And, now time to build a wing, which means first time to cut out lots of tiny little formers...

Some thoughtful individual made templates for each wing rib, good on them. There's 8 copies for rib 9, because the plan requires 8 of them, but you can do it with just 1, by attaching 8 pieces of wood with Super 77 and then putting the template on top of that.

These are all the copies of rib 9, sanded to shape. The scroll saw is only for making the rough outline, and they're finished off with sandpaper.

All the ribs, done. One of them has a booboo, caused by some accidental heavy-handedness while trying to get them unstuck

Wings assembled. The way they have you implement the dihedral is a little weird, as you cut out the center section of the wing and then add the dihedral braces there. I had a minor screwup as I glued the strut into the center section ribs, which would prevent me from adding the dihedral I put some acetone on it and let it soak, and that should debond the glue. Nobody makes trailing edge stock small enough for this; I considered sanding it off the plane, but I think it'll be easier to do it with it assembled as I'll have the wing ribs as a reference for what angle they should be sanded at.

I also used the last of my thin CA. Time to pick up some more...

I quite missed doing these small scale balsa builds. Especially because in all, I've probably used like $2 worth of wood so far. Maybe I'll do one for myself, especially as I've got tons of micro electronics from dead UMX planes lying around...

 

[TooJung2Die]

It's going together quickly. No motor? Looks like you are sticking to having to tow it or chuck it.

 

[speedbirdted]

It has a hook for a high start launch, though I have a feeling any amount of bungee pull that would result in a decent amount of altitude would just rip the wings off it. I'm not sure how it'll be launched, but I'm not the guy in charge of figuring that out here

 

[TooJung2Die]

True, but it isn't obvious at this point in the build.

 

[Paracodespoder]

@Paracodespoder made one of these if memory serves. I'm a bit slow so that doesn't help

Built but never covered, well, I tried to cover it....

 

[speedbirdted]

Built but never covered, well, I tried to cover it....

What did you try to cover it with?

Mega progress today. Wings sanded and joined. This has got to be the lightest wing I've ever put together.

Nose block is also sanded. There's a little skid that goes underneath it, and the way it's installed is not well specified in either the building instructions or the plans. There's some ambiguity in how it gets installed according to some finished build pictures of other planes I found. This looks about right to me...

Horizontal stabilizer and elevator are also mostly finished. I have some sanding left to do on the elevator, then I'll build the rudder. As specified by my buddy I will not glue these on; I think he prefers to cover them first as do I.

I'm not working off any plan for stick building these. I just TLAR'd it and it came out good enough for my liking.

 

[Paracodespoder]

Cellophane from the dollar tree, I built the wing frame very poorly and it snapped when shrinking the cellophane, yours looks great by the way!

 

[GliderFlyer]

Cool! A RC frog junior sailplane. I printed the plans for this a while ago from outerzone but then didn't build it. I would probably have built it as free flight tow-line. I scratch built a Scimitar glider and covered it in transparent green plastic covering film(don't know what brand though). It flew well, so I made another one large enough to carry my radio gear but only got to fly it once before it got broken.

 

[speedbirdted]

Cool! A RC frog junior sailplane. I printed the plans for this a while ago from outerzone but then didn't build it. I would probably have built it as free flight tow-line. I scratch built a Scimitar glider and covered it in transparent green plastic covering film(don't know what brand though). It flew well, so I made another one large enough to carry my radio gear but only got to fly it once before it got broken.

You should build it! With a balsa stripper you can use a ridiculously cheap amount of wood. It's an easy build too. Usually with small builds there are some parts that can be majorly frustrating but with this it was pretty much smooth sailing throughout. I really want to build myself one and cover it with Doculam or maybe even tissue like my friend wants to do.

Last step, vertical stab and rudder were built up today. People say I go crazy with the amount of pins I use, but it's just to make sure nothing will have any ability to move. With pieces this small, there is no pin or needle thin enough to go though it without causing any cracking. Plus it leaves holes, and that's just nasty. So, I place pins holding the edges with others inserted at an angle to hold everything down. Having a cover of 1" thick insulation foam on your building table works wonders in doing this.

And here it is, all sanded up. The same treatment was given to the rudder though it needed less as the shape was more or less determined by the outline of the wood parts rather than having to sand stuff away.

And I guess that's it. Dry fitted everything, seems fine. Now let's hope the other guy does his end of the build well

 

[TooJung2Die]

Great job! I hope your friend is as good with tissue covering as you are with balsa!

 

[GliderFlyer]

Here's an idea: modify the tail and add wing struts and presto! A slingsby prefect. Or maybe the skylark. The resemblance is there, I had to point it out.

 

[speedbirdted]

VMC has a 30" Slingsby kit. There's also plans for it. You might be able to bash this into one, but the fuselage would end up much thinner, to such a degree that I don't think any UMX board would fit in it. The one I used in this one is already on the very smaller end of what they make.

 

[GliderFlyer]

I made up my mind to build one of these. It would have gone through modifications to look more like a slingsby skylark, but then I found out that besides the Frog junior sailplane, there are also plans for the frog slingsby skylark! I will be building this instead. No RC, just good ol' free flight. Should I do a build thread for this one?

 

[TooJung2Die]

If you do your own build thread it will be easier to find if someone searches for it. There's no such thing as too many balsa build threads!

 

[speedbirdted]

Should I do a build thread for this one?

Yes! Don't be like me and hijack someone else's thread

 

[GliderFlyer]

Yes! Don't be like me and hijack someone else's thread

Ok I will probably get started this weekend.

 

[Willy Nillies]

What an awesome build! Thank you for sharing!