I’ve had requests on tools and materials we use to build our wings, as well as a more detailed description on how we build them. I’ll be doing a detailed description on how to build the wings for my “how to” section on this website in the next few months. Here’s already the overview of tools and materials.
- Foam cores: we’re using foam boards from Schurg (https://schurg.de/), approximate size: 100x50x6cm
- Ebechi wood: we use 0.6mm ebechi wood, prepared by a carpenter we know or through RIK Modellbau (https://www.balsa.ch/shop/abachi/).
- Carbon: our favourite carbon layup is the Carbon Cloth biax ±45° 100g/m² 127cm (https://shop.swiss-composite.ch/pi.php/Verstaerkungsfasern/Kohlefasern/Carbongelege/TK-Carbongelege-biax-100gm2-127cm.html). This is biaxial prepared in a 45° angle, easy to work with and relatively cheap. We’ve used it in all our recent builds.
- Carbon fiber sleeves for the main wing spar: we use three different types:
- R&G 200.4008 inner part
- EMC VEGA SC1062 middle part
- R&G 200.5211 outer part as well as the spars at the control surfaces
- Core of the main spar: here we use Rohacell. It’s very easy to sand to shape, but ridiculously expensive. I buy a smaller plate and glue together the bits using 5 minute epoxy resin (See: https://shop.swiss-composite.ch/ki.php/Sandwich-Werkstoffe/Hartschaeume/Rohacell.html). The core of the spars at the control surfaces is the foam that was cut out (carefully!).
- Resin: until recently we mainly used EPIKOTE MGS LR285 resin (https://shop.swiss-composite.ch/pi.php/Harze/Epoxydharze/Laminieren/Epoxy-Arbeitspack-L285-285-LF1-50-1Kg.html). I prefer the 210 minute hardener, but unfortunately the sale of that is no longer allowed to private persons (toxic) – we can now only get the 50 minute hardener. Because of this we also started using the L-385 (resin) and LH-386 (90 minute hardener) (https://shop.swiss-composite.ch/pi.php/Harze/Epoxydharze/Laminieren/Epoxy-Harz-L-385.html). This also works very well and gives you 90 minutes. The shorter hardening times can be compensated by making multiple smaller batches rather than a single batch of resin.
- Other materials include:
- UHU Por to glue together the foam shells (upper side)
- 5 minute epoxy (I like UHU Schnellfest) to glue together bits of the wing spars
- A good thin brown packing tape to apply to the edges of the foam moulds to prevent the ebechi being glued to these by excess epoxy resin. Note that not all brown packing tapes are equally good. We use the cheap one from our local “Landi”
- Painters’ masking tape – both the cheap white one (3M) and the wax version. For the wax version it’s important to get a good (expensive) version, not the 3M/TESA, as epoxy like to stick to/run under this (I really like this one: https://www.malbera.ch/Z__produktedokumente/Permafix%20750.pdf).
- Vacuum Pump. I use two different pumps, a small and a bigger one. The smaller pump is very good, but when you build the wings the extra power of the larger version gives you a lot of extra security in case of minor leaks.
- For smaller parts (elevator, rudder), I use the R&G Standard 6L P-1 (https://shop.swiss-composite.ch/pi.php/Vakuumtechnik-Infusion/Pumpen/KNF-86-Vakuumpumpe-Standard-6l.html)
- For the wings I use the P2-N 30L (https://shop.swiss-composite.ch/pi.php/Vakuumtechnik-Infusion/Pumpen/KNF-18-Vakuumpumpe-15L.html).
- Vacuum bag, tube, connector and seal: all these bits can be found through R&G. I close the vacuum bag using a U-profile with a fitting tube. Press the bag into the u-profile and then press the tube into the U-profile to close it.
- Paint roller for applying the resin: I use the “Radiatorenroller Felt extra kurz (Serie 2307)”, 50mm, supplied by Malbera (https://www.malbera.ch/Z__produktedokumente/Farbroller,%20Farbrollerzubehoer.pdf). It has short hairs and doesn’t absorb too much resin. I use disposable carboard trays (supermarket) to roll the resin into the roller.