Making the spar

A primary glider build by kids for kids
All you need are the woodenparts for the laminated spar caps, a straight table, glue and ... CLAMPS.
First we clamped like this. Hans engels warned us for two things. First, clamping straight on the wood can damage the wood. Luckily the harm was not done. Second, the clamps don't spread their force, even if they are placed at +/- 20 cm (+/- 9 inch). You need to spread the power by laying a thick part on top and clamping that one. We used some badly delivered oregon parts. Make sure they are high enough or they bend too.
Milko, Simke, Jeroen and Karel-Marc are placing the parts together. Note the black line on one part. It indicates a deformation in the wood. This way we make no mistakes while laying the laminated parts on top of each other. Note the long and "high" block next to the glued parts.
Jeroen, Karel-Mark and Kevin have put the clamp-aid on top of the glued parts and are now placing the clamps. First place them lightly, then put force on the middle ones and go from middle to end. Note: I first put some clamps horizontal to prevent the parts sliding while placing the vertical clamps. The horizontal one are removed once the vertical ones are TIGHT.
Just the beginning of placing the small blocks on the right place to fix the rear spar caps. The bench is not perfectly level. I will do that the day I will glue the parts. I fear that the workbench will get unleveled by the other students while we (volunteers and I) am not there. Probably accidentally, but without saying it to me, because they don't see the trouble in just touching or pushing the workbench). I will glue during the last day hours of school, glue will be hard the next day.
Here you the easy way we used to keep the parts together while glueing. Just hit a few wooden blocks on that working table. You can also see that I no longer use plastic covering of the working table. I prefer just sliding paper under the part that will be glued. I had a bad experience with still needing to drill a hole in the working table in the front spar assembly. A lot of dust got under the plastic and it was a hard job to get the dust away.
Glueing the plywwod on the centerpart and the stiffeners in the wingtip. Here you see the problem I had ... the workbench was too wide. I had to make some strange press system to clamp the center parts (plywood on caps) while gleuing.
The spars are made in a single piece. Later to be cut into three parts after the hinges are placed. The wingtips had to be upward to get the needed dihidral. It was no problem. I used a triangle to glue the tips. Triangle is not yet placed here.
The front spar assembly. Still need inside varnish and plywoodcovering on this side. The stiffeners and innerblocks can be seen. SPECIAL NOTE: when covering the open side with plywood, don't forget to varnish it as well. BUT not varnish the places where you intend to glue. Glue doesn't stick to varnish. Leave 1cm of space free next to the edges and use glue enough. The expanding glue which i used would cover the non-varnished area next to the stiffeners and protect the wood against the elements. DON'T FORGET THE VARNISH BEFORE COVERING!!!
Other side of the assembly. Note the hole inthe middle. I still haven't figured out how I will place the central steeringrod. So I leave that place open till inspiration flies in.
Inner blocks and stiffeners.
Detail of inner blocks. Here the connectons CAN be placed if the wings will be used on a HM14 or HM293 or HM360 fuselage. I will probably use them to test mount the wing on my own HM14/360.
I only have to varnish the insides of the spar and cover it at one side. But I could not resist the force to place a fake rear spar and put on a few ribs. It starts to look like a wing, doesn' t it. My students saw for the first time we are ... really building a airplane! The ribs you see here are of a previous rib building system. It are not the ones which i explain in the rib building guide here.