Frog Slingsby Skylark scratchbuild

[GliderFlyer]

Here is my build thread for the 27” slingsby skylark tow line glider. The plans come from outerzone.co.uk. I was inspired by The build thread by speedbirdted’s thread Frog Junior Sailplane scratchbuild and wanted to build my own. I actually may build the junior sailplane, since I already cut out the ribs(before I discovered the Skylark plans) but the focus For this thread will be on the skylark. I am in short supply of silkspan too, so that could be a limiting factor.
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This is my building space, since the top of the desk is occupied by the Willy Nillies eaglet 250.
Really basic balsa stripper. Works well enough for me.


Alright I’m going to start cutting out some pieces, the tail surfaces will be stick built to save weight. By the way, does anybody know how I can get this windshield done? I have no experience with vacuum forming, and am willing to learn, but only if there are not any easier methods for making round windshields.

 

[speedbirdted]

The windshield looks like a compound curve so there's no easy way to do it with a flat sheet without vacuum forming or doing something like it. If you have access to a 3D printer you could try using PVA and sandpaper or PVB/ABS with chemicals to get a very smooth windshield though it won't be nearly as transparent as something vacuum formed. Making a vacuum table isn't terribly hard actually; if you have a shop vac you can build a box out of wood and pegboard, seal it with epoxy and rubber tape, and make frames to stick somewhere where it gets hot, like an oven. Be careful though!

On something this tiny, you likely do not need silkspan. The ultra light Japanese stuff would work perfect. Or you could use doculam.

How does that balsa stripper work? Seems to me like trying to just slide pieces along the x-acto would be begging to get wonkily cut pieces with unintended bevelling. But if it works for you...

 

[GliderFlyer]

The windshield looks like a compound curve so there's no easy way to do it with a flat sheet without vacuum forming or doing something like it. If you have access to a 3D printer you could try using PVA and sandpaper or PVB/ABS with chemicals to get a very smooth windshield though it won't be nearly as transparent as something vacuum formed. Making a vacuum table isn't terribly hard actually; if you have a shop vac you can build a box out of wood and pegboard, seal it with epoxy and rubber tape, and make frames to stick somewhere where it gets hot, like an oven. Be careful though!

On something this tiny, you likely do not need silkspan. The ultra light Japanese stuff would work perfect. Or you could use doculam.

How does that balsa stripper work? Seems to me like trying to just slide pieces along the x-acto would be begging to get wonkily cut pieces with unintended bevelling. But if it works for you...

I try to keep the sheet as perpendicular as possible, but of course, you can only get so accurate that way. My margin of error when it comes to modeling is not as small as it should be.
As for covering, I only have silkspan, left over from a few guillows kits. Don Ross says the difference is only .2g/sq foot.



Thanks for the comment, though.

 

[leaded50]

check plastic bottles! One of my models do also have "similar" shaped canopy style.. right cut from a bottle fixed it.

 

[GliderFlyer]

I need to build two of these, on top of each other. I’m building over 1/2” insulation from Lowe’s. A sheet of 4’x8’ cost about 10$, and is way more than I need. Food wrap is used to keep the glue from sticking to the plans. I haven’t glued yet, I will be using super thin CA for this build.
The balsa stripper actually works quite well. Here’s a strip I cut

 

[GliderFlyer]

Ok so I glued up the fuse side, it wasn’t completely a disaster, but that thinCA is hard to apply accurately without the proper tip. As a result, the CA stuck to the pins and then to the food wrap through the pin holes. I was able to sand most of it away, but I don’t want to deal with that for the rest of this build, so I’m switching to this

It should slow down this build, so I’m not rushing too quickly. Time to break these bad habits.

 

[GliderFlyer]

Finished one fuse side and the other is drying. Also drying is the horizontal stabilizer. Next up is the vertical stabilizer.
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[GliderFlyer]

A cardboard jig to shape the fin. I split the balsa down the middle, then soaked it in water. Once it is dry, it will be hardened with thin CA.

 

[TooJung2Die]

thin CA is hard to apply accurately without the proper tip.

I like your super simple stripper idea. You can buy these CA applicator tips but I make them from plastic handle q-tips. Melt the plastic tube over heat and pull. It stretches out and make a very fine tube. For some reason it doesn't clog for a long time. If it does just clip off the clog.


Jon

 

[GliderFlyer]

I like your super simple stripper idea. You can buy these CA applicator tips but I make them from plastic handle q-tips. Melt the plastic tube over heat and pull. It stretches out and make a very fine tube. For some reason it doesn't clog for a long time. If it does just clip off the clog.
View attachment 178159

Jon

What a great idea. just another question about CA though, the thin stuff likes to run down the outside of the nozzle and then dry there. Over time, it can build up and then I cant fit the cap on anymore. Has anyone figured out a way to prevent this? I bet the applicator tips probably make a difference in excess dripping on the nozzle, but then how does the cap fit on when you have the applicator tip attached?

 

[Turbojoe]

What a great idea. just another question about CA though, the thin stuff likes to run down the outside of the nozzle and then dry there. Over time, it can build up and then I cant fit the cap on anymore. Has anyone figured out a way to prevent this? I bet the applicator tips probably make a difference in excess dripping on the nozzle, but then how does the cap fit on when you have the applicator tip attached?

As soon as I see any clogging or buildup I toss the offending applicators into a jar of acetone. It cleans them up like new again. I probably have applicators going on 20 years old.

Joe

 

[TooJung2Die]

how does the cap fit on when you have the applicator tip attached?

You don't need a cap during a build. The hole in the tip of the applicator is so fine that It acts like a cap. Keep a paper towel handy to wipe off drips on the tip before you put the CA bottle down. Remove the tip and cap the bottle after you're done using it.

 

[Turbojoe]

You don't need a cap during a build. The hole in the tip of the applicator is so fine that It acts like a cap. Keep a paper towel handy to wipe off drips on the tip before you put the CA bottle down. Remove the tip and cap the bottle after you're done using it.

Very good point. I also squeeze the bottle as I'm wiping the tip so when I let off it pulls the tip clear of any CA that could dry there. I can usually go weeks that way without a clog.

Joe

 

[GliderFlyer]

It’s probably unnecessary, but I wanted to try it out.

A fuselage squaring jig I made to hold the formers together while the glue drys. I got it from Don Ross’s book Rubber Powered Model Airplanes. At first the rubber bands were too tight and were really hard on the longerons. I made the longerons out of softer balsa since wasn’t paying attention at the time. But there are more that go on later so I will make sure to use more stiff balsa then.

 

[GliderFlyer]

I did a building spree and finished the fuselage all at once. I didn’t take pictures of the process, but it’s just gluing on more stingers so you’re not missing much. I did use thin CA for building off of the board, except for the first three formers seen above. Here is what it looks like now.

The front sheeting was pretty hard. I had to cut it from 1/32 balsa 3 times since it kept on cracking in the thin spots. I then curved it on a round battery and used a heat gun to help it dry faster. It wasn’t flush with the stringer below it, so I used the glue as a filler. I still have not found a plastic bottle the right shape and suited for the canopy, but I’m sure I’ll find something. But if I do, I will need to buy canopy cement or find an alternative. Any thoughts?

 

[leaded50]

Here in Norway we have a 2 litre bottle "Farris", who is carbonated mineralwater. That bottles is my main use for canopys, light bluish color.

- just look at bottle here , closer to top, there you got close to the bulby shape..

 

[GliderFlyer]

Here in Norway we have a 2 litre bottle "Farris", who is carbonated mineralwater. That bottles is my main use for canopys, light bluish color.

- just look at bottle here , closer to top, there you got close to the bulby shape..

Yeah, I was thinking a water bottle like this one,

but all the water bottles are too large. I would like it to be a bubble and not just a curve. It goes almost 90 degrees in approximately 1-1/2 inches.
I had a better idea of using travel sized shampoo bottles, but I can't find any around the house that are suited.

 

[leaded50]

1 1/2 inch X 1 1/2 inch x 3 inch from that bottle gave me a canopyfront with bubble shape from side & top profile .
I bet its possible find a bottle with correct shape... but yeah.. it need searching...

 

[GliderFlyer]

just to clarify-
I meant 1-1/2 inch from corner to corner

the numbers are inches

I have been considering the soap bottle in the kitchen. It is the smallest I can find. This plastic bottle idea is really cool. I bet it would awesome on Grifflyer's Mini Master Series Spitfire.

 

[GliderFlyer]

Got working on the wings tonight. I want to have this done by Saturday, so I will also begin to cover the fuse.

Yes, I do use my building board as a cutting board too. It won’t last as long, but the huge sheet I have takes up a lot of space so I am not sad if it gets used up quickly.

I will be using an Elmer's glue stick to attach the tissue, then shrinking it with water. I dont really dope the covering on my models, never have, so long as you keep out of trees, it should be fine.

Oh I almost forgot- the tow hook needs to be inserted into the keel. I will try to get pictures of that before it is covered.
To be honest, I didn’t build referring to the instructions on the plans. I just put the pieces where they go and they fit. I should probably check the instructions to make sure I’m on the right track.