GPM Gil Glider Build

[wb4jjj]

I bought this from the Old Troll at the convention, and am boldly trying to do a build report. No one knows if this will get to completion, but I'll try. The model is GPM's Gil Glider. GPM catalog number 207, published 3/2004.

This is the result of the first day's work. GPM rates this as 2 out of 3 difficulty.

Alan

[member_3]

Hooray! One of my old "treasures" is getting built. The build looks clean and true so far - keep up the good work!

[modelperry]

Hey Old Troll, I plan on building the "old treasures" that I got from you too!:D But first I will enjoy watching this build from Alan.

I wish you well, Alan, and will be keeping track of your build. Looks really good so far, keep it up!:)

Greg

[redhorse]

This looks great! I've wanted to see one of these gliders get built. Looks like you're doing a really good job so far - I bet you finish it!

[Gil]

For some reason I like this build. . . ,

+Gil

[Tim Crowe]

Looking forward to this build- good luck with the wings

Tim

[wb4jjj]

Well, I needed some luck with the fuselage tube. I ran into the same problem with the 1/50 scale Marek glider I showed at the Convention.

Here's the grabber. With the Marek glider, the fuselage tube (the section connecting the cockpit with the tail section) was printed on paper with the grain going across the short width of the piece. This meant that the paper's strength resisted the rolling and the piece cracked when rolled. It is amazing that experienced designers who have worked with paper for years don't realize that paper has grain and will roll into tight tubes one way if the paper is light enough, but printed 90 degrees in the other direction, you can't roll it at all.

On the GPM model, it was printed with the grain running the right way (long way of the piece) , but the paper was way too stiff to roll smoothly.

You can tell the way the grain runs by taking a full-sized sheet of letter paper and rolling it in each directions. You can tell the cross-grain direction by how the paper resists rolling in one direction. Sorry for the lecture, but I'm an old printer from way back and paper grain is one of my hot buttons.

There are a couple of possible solutions that I've used before with some success. One is to sand the back side of the piece before it is cut out in order to thin the paper so it is less stiff. 150 grit paper seems to work well and is a good grit compromise between tearing the paper and taking weeks to get it thin enough.

The second approach is to wet the back of the piece and roll it while damp. This is the method I chose. Quicker than the sandpaper method, but it takes guts. But it works even with inkjet printed pieces if they are properly sealed. Careful is as careful does, though.

So I wet a paper towel and went to work. And it did work. You have to glue it while wet which means water-based glues are a challenge, but they will hold with some fiddling. I had one small bad seam area but that will be covered by part of the lower body enclosure.

BTW, the water will dull the printed surface a tiny bit and raise little hairy things up, but I don't think you'll notice once the model is completed.

Wings are next, but now I'm nervous after the good luck wishes....

Alan

[member_3]

The description was scary but the results look like it was a piece of cake. I have to agree with the comment regarding parts layout and paper "grain." It seems like the problems show up more on published printed models as opposed to the electronic format. Perhaps it has to do with keeping the page count down on printed models. Having solved that problem as smoothly as you did, I don't think you will have any problems bringing this little gem to a successful conclusion.

[Don Boose]

Alan -- Great work on a beautiful flying machine. I enjoyed your gracefully-written description of the build process and the way that you overcame the problems of paper grain.

Also, please accept my apologies for misspelling your name in my IPMC report by inserting a supererogatory "L" in the middle.

Don

[member_3]

LOL - I have checked with those who know and that was the only time the word "supererogatory" has been used on any paper model forum - ever! Thank you Don "Word for the Day" Boose! Wink, wink, nudge, nudge, still love ya, Don! :)

[wb4jjj]

A bit more progress, this time adding the tail section.

I've concluded that the card stock used by GPM on this model is a bit too heavy. Rather more like US 110 pound stock rather than the usual US 65-67 pound stock used on most paper models. As a result, even when the grain is correct, the paper breaks rather than smoothly bending into a tight round, particularly on fin and stabliizer leading edges. The paper has to be handled carefully. Check the leading edge of the fin and stablizer to see what I mean. This weight stock is fine on a 1/33 large fighter or bomber, but this one-man glider at 1/33 is quite tiny, hence the need for lighter paper.

I used a dental tool that I have for scoring to smooth out the breaks in the paper on those leading edges. Paper is like sheet metal in miniature and I used the spoon shaped end on the dental tool to smooth down the paper breaks, sorta like Leepu on cable TV's Chop Shop, if you know what I mean. However, I used light hand pressure instead of a hammer. It looks OK.

I also use the spoon end of the tool to rub over each and every cut edge. X-acto and similar blades leave a raised place on cut edges. The spoon end will rub down this raised line and sort of weld the disturbed cut edge back into the paper, and seemingly hardening it as you go.

I also made up some angled paper glue strips (see photo for tool and strips). I used these to glue the trailing edges of the rudder and elevators.
When these strips are used, it allows the glued edge to separate tight at the edge and doesn't make it look like someone stepped on it. Most everyone does this, I know, but I thought I would mention it as particularly important in this model. GPM leaves you very much on your own as to how parts are to be attached, so there is room for innovation at every step as to how you make up glue tabs and strips.

The stablizer uses a box spar to give it shape, and, along with the angled glue strips, portrays the prototype airfoil section pretty well.

This model has a large number of unconventional assembly approaches. For instance the body skin wraps around the card skeleton, which leaves little margin for error. The photo on the front of the kit exhibits some obvious boo boos, which makes me feel much better about the way my Gil looks....LOL.

Alan

[Don Boose]

Thanks for the reminder about the training edge strips, Allan. I think this is a very good tip that is useful for a lot of models.

I appreciate your lucid and thorough explanation of how you are building this beautiful sailplane. Although I am not likely to build this one, I can appreciate a pretty model airplane and your techniques are widely applicable.

Don

[member_3]

Ahem...Don, it pains me to bring your attention to the additional supererogatory (or is that supererogatory supererogatory) use of the letter "L" in Alan's name. I suspect you did it simply to bait me, knowing I cannot resist any additional admonishment of accidental alliteration and other such grammatical "faux pas" you may make.

And just so I don't get off thread...excellent progress and thanks for the trailing edge strip reminder...a most valuable technique!

[Janx]

An elegant aircraft and beautifully clean build so far. Looking forward to seeing more of this one as you progress.

I am going to have to look that word up now...

[wb4jjj]

Now for the wings.

Pretty straight forward stuff, even if the directions are in a language I don't understand. I mounted all the parts for doubling on hot-pressed Strathmore board from an art store, about .8 mm thick.

There are two steps, a wing rib and bracing...followed by a box spar, subtly tapered from aircraft body to tip. This box slides over the main spar and the bracing.

This kit has a very neat second wing spar (not really visible here but which shows in my earlier posts), which, when centered on the rib, correctly sets the angle of attack for the wing. Very neat.

I'm building using mostly Aleene's Fast Dry tacky glue. It doesn't allow much time for adjustments, but is very handy when heavily gluing wing spars and braces. Lets you really move along.

Next will follow the wing skins, which I understand are going to be tricky. There's no support for the outboard span on the wings which have a slight gull shape. In addition, the actual wing tips bend downward, at an angle for which GPM has provided a template.

This next step will take a couple of days worth of spare time to cut out and form, so relax. Along the way I'm going to have to decide if I will thermoform the canopy or use acetate sheet.

I'm enjoying just getting this build this far along.

Alan

[Don Boose]

Good and fast progress, Alan. It looks like a well-engineered wing structure.

Disregard the Trol behind the curtain. Meanwhile, I am trying to type "Alan" one hundred times in hopes of getting it right.

Don

[member_3]

LOL - now he deliberately misspells "Troll" trying to get another rise out of me! Well, it won't work, my colossally cantankerous colonel. I remain faithful to the theme of this thread and once again congratulate Alan on his clean, skillful build.