Build Thread - X-RES 2-meter Sailplane from Germany - RC Groups
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Jul 05, 2016, 06:01 PM
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Build Thread - X-RES 2-meter Sailplane from Germany


The X-RES is a sailplane kit designed to the specifications for the new RES class of competition becoming popular in Europe.

I became interested in the 2-meter/RES/wood kits myself from seeing, building and flying the excellent PuRES kit from Josef Gergetz. The PuRES has generated a lot of interest in our local area, but Josef cannot meet the enormous demand. Accordingly, a small group of us has gotten together and we are examining as many of the new kits that we can obtain. Our ultimate intent is to sponsor a competition sometime in 2017 for these new airplanes.

The X-RES meets the specifications for F3B-RES competition: 2-meter span, wood construction and controls limited to rudder, elevator and spoiler. Like the PuRES and Slite (I have built several examples of each), the wing is 5-panel polyhedral. Like the PuRES and Slite, wood parts are CNC-routed, with ecellent sticks and sheet provided. Unlike the PuRES and Slite, the construction is all wood. There is no significant carbon in the primary structure. The wing spars are I-beams, with spruce caps and balsa shear webs. Balsa sheeting from spar to leading edge results in a strong, rigid D-tube wing section. Unlike the PuRES, the tail surfaces are conventional, and the horizontal tail is all-flying, using a trick little assembly of composite plates. The fuselage is a self-jigging box of balsa and thin plywood.

The only instructions I have are in two versions: (1) German, and (2) near-German English. However, the pictures are excellent, the parts count is low and construction is straight-forward. You won't see pictures today, but I have assembled about 80% of the wing center section without adhesive, and it all fits well. There is a neat feature: the angle jigs for the end ribs (5- and 6-degree angles) are keyed, so the 5-degree angles fit only in the base labeled "Five Degrees", and the 6-degree angles likewise in the Six Degrees base.

In years past, I built a whole series of gliders with wood I-beam construction, and the results were always stiff and strong. I am very confident in this form of construction.

In my numerous PuRES and Slite builds, I have developed a high sensitivity to CA. The X-RES lends itself to aliphatic resin, which is much more benign.

I am still getting my bench set up for this project. It is required to pin down sheet and various parts to a build board, and I have to do some house-keeping to get set up properly. So, no sooner than tomorrow, look for pictures. I will be starting out of sequence, with the wing center section, followed by the fuselage.

Yours, Greg
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Jul 05, 2016, 06:16 PM
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slowmatch's Avatar
Looking forward to it Greg

Jon
Jul 05, 2016, 06:27 PM
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Sweet! Easy build. Flies great!
Jul 06, 2016, 03:38 AM
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Ndanger's Avatar
Excellent... another one of those amazing kits from Germany and a front row seat for the build
Jul 06, 2016, 12:06 PM
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Quote:
Originally Posted by glidermang
I became interested in the 2-meter/RES/wood kits myself from seeing, building and flying the excellent PuRES kit from Josef Gergetz. The PuRES has generated a lot of interest in our local area, but Josef cannot meet the enormous demand. Accordingly, a small group of us has gotten together and we are examining as many of the new kits that we can obtain.

Yours, Greg
After you finish this build, how about doing a BABA JAGA Competition? I'd love to see a build thread on it. Of course, I'll be following this thread because its interesting too.
Jul 06, 2016, 11:24 PM
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X-RES Wing Center Section


Some one said "Easy Build". Quite right.

I started just fiddling with the pieces, and found that they went together very nicely. Fit was excellent, and sanding after removing from the sheet was easy and quick. The wood selection is quite nice, and seems totally appropriate to the intended use.

I started by simply joining the lower spar cap of spruce, to the sheet of 1.5mm balsa intended for the wing lower surface. Easily done. Next was joining the two 5mm balsa ribs to the two 1.5 ply ribs that make up the center section hard point. Also easily done - everything lines up quite nice. The instructions recommend epoxy for the center ribs, but I used aliphatic resin.

I pinned the sheet down on the plans, over waxed paper, and trial-fit the and other ribs. The entire assembly went together and staid together without adhesive. So, I pulled everything off and got to work.

Glueing the ribs to the lower sheet is quite easy with CA, but I'm trying to stay away from that stuff for a while. Following the instructions and with CA, you just lay the parts down, and drop in a bit of thin. For the aliphatic resin, I made a pair of wedges that would lift the lower sheet up to the ribs as each was fit onto the spar, and hold it long enough for the glue to set. I laid down a rib, inserted the wedge; laid down its opposite on the other side and wedged that one; by then the I could remove the first wedge to use on the next rib.

The center rib went down first, then the left and right spar webs. I centered the webs on the spruce spar caps by eye, then inserted each rib to verify placement. I removed all the ribs once more, then got down to gluing each one on. It is critical to keep track of which rib goes where. They taper, so are all different, but they don't taper much - and yeah, I screwed up, but I was able to recover gracefully. This time.

After the ribs were down, I fit the trailing edge on, then built the spoiler boxes. Here, I realized that the plans were ambiguous, and I didn't have the 2mm sheet they seemed to call for. However, 1.5mm sheet fit all the cut outs provided, and the result is a smooth surface for covering. The 1.5X10mm sheet for the spoiler boxes is cut from excess 1.5mm sheet from the lower surface. The spoilers are made from 3mm balsa provided as a simple plank. The plank is just exactly as long as the overall spoiler box, so I cut the 40mm spoilers, then cut off the ends to make the ends of the spoiler box.

I cut a 6mm wide strip from the excess 1.5mm sheet to make the false leading edge. When I was done, there were no wrinkles or discontinuities in the lower sheet, viewed from the ends of the span.

The result is straight, and light. Tomorrow, I will trim the lower sheet and false leading edge, than sheet the top. After that, fix the leading edge on, and use the handy rib templates to shape the wing. The balsa is very good quality, and the job should not take long.
Jul 06, 2016, 11:34 PM
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georgeg:

Our group is sponsoring three more builds after this one, but not (unfortunately) the Baba Jaga. We selected those that had appeal at the moment, and were suddenly struck buy the size of the task, and got scared. Give us time, though! If we can carry out our scheme to comparatively fly these airplanes, we may eventually get to that one.

Yours, Greg
Jul 07, 2016, 12:45 AM
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The spoiler boxes are built from scraps. I don't think the plans say that specifically.
Jul 07, 2016, 12:49 AM
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Very nice Greg !
Like me, the X-RES is "Made in Austria"
RES had been swapping from Germany to Austria, and the guys there developed a lot of very nice planes.
The X-RES is a good performer !

Josef
Jul 07, 2016, 04:03 AM
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slowmatch's Avatar
Great work Greg and thanks for the detailed thread.

For any XRes pilots in the UK - we are attempting to launch a postal duration competition to promote 2 metre flying over here:

https://www.barcs.co.uk/forums/topic...ons-in-the-uk/

You never know, we might get some actual competition at some point. Please pop along and express any interest

Jon
Jul 07, 2016, 01:32 PM
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Ndanger's Avatar
Quote:
Originally Posted by slowmatch

For any XRes pilots in the UK - we are attempting to launch a postal duration competition to promote 2 metre flying over here:

Jon
Your forum has some great pictures of some fine sailplanes. Could I ask if you know the names of the gliders that are in the group picture, they look like a dandy selection of flying machines.

Steve
Jul 07, 2016, 03:35 PM
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Greg, one tip.

You can finish the center panel as per instructions making sure the joiner tubes are 90 degrees to the root spar. Use the included angled piece of wood as a tool.

When you make the next section don't glue the final rib until you test fit it to the center panel. You'll get a much better result. I used the angle gauge solely and you get like a 1mm gap on the bottom of the joined area. Not a big deal but if you are a nit picker....well...it is
Jul 07, 2016, 07:42 PM
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slowmatch's Avatar
Steve, the two group pictures are lifted from the German RES forums.

The first is a little older I think and shows several PuRES, Baba Jaga's, a GezoRES (top middle), two PicaRES and I think two AndREaS (winglets) plus one or two I dont know.

The second group photo is more recent and shows lots of Slite's (elliptical wing) and PuRES, some Baba Jaga Competitions, plus a MadRes (purple model out right held on its wing tip) and an Antist-RES (high aspect elliptical wing far bottom right.)

Jon
Jul 07, 2016, 09:53 PM
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Bmwjoon:

Got it! Many thanks!

Yours, Greg
Jul 07, 2016, 10:01 PM
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And now, more build.

Yesterday, the wing center section was completed to the point where the next step was to add the top wing surface. To do this, I first took down the false leading edge with a razor plane, then masked the ribs with tape (exactly as per the kit instructions, which are really pretty good). The pictures show this step. I then used the World's Best Sanding Block to finish things to perfection. I got the World's Best Sanding Block from none other than the Old Buzzard himself, Buzz Averill. Buzz was the inspiration and much of the source for the Old Buzzard's Book of Soaring, by Dave Thornburg. Buzz himself died last summer, and his widow auctioned off a lot of his tools and supplies.

When sanding, I tried to keep the rib upper curvature in mind, then stopped when the tape showed signs of abrasion. The result: perfect.

I trimmed the lower surface pretty close entirely by eye, then taped the center section to my cutting board. I applied the glue, and taped down the upper surface, and let things set.

Once the glue was set, I trimmed the upper surface by eye, then used my razor plane once more to take things down to nearly flat, finishing off with the World's Best Sanding Block.

I applied glue to the false leading edge, then taped down the 4X10mm leading edge stock. Unfortunately, I did not have much time today, so trimming and sanding to final shape will have to wait until tomorrow. I have used this sort of leading edge on many kits over the past forty years, and I am very confident I will not screw it up, especially with the templates supplied in the kit.

Yours, Greg
Last edited by glidermang; Jul 07, 2016 at 10:35 PM.


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