Archive for September, 2009

Mike Blyth and James Pitman, co-owners of South Africa-based The Airplane Factory, on Aug. 27 completed an around-the-world trip in the Sling, a sport aircraft they built that makes significant use of composites. Their 40-day trip took the duo through 13 countries and covered a distance of 45,150 km/28,055 miles.

The plane uses glass/epoxy composites in the main undercarriage, wheel covers/spats, the engine cover and the struts. The prop is also made with composites, although material fiber and resin type were not specified. The Sling 002 in which Blyth and Pitman flew is a modified version of the company’s standard Sling craft, but with some modifications. These included an additional 15 layers of glass fiber on the undercarriage, and an additional 15 layers of glass fibers on the struts to reinforce the landing gear to withstand the weight of additional fuel for the trip. The company says that when the Sling enters production, more of the craft will be made from composites. All the composite materials were supplied by Aerontec, based in Cape Town.

When fully loaded with fuel, pilots and their luggage, the Sling 002 weighed just 900 kg/1,984 lb. It has a cruising speed of about 90 knots indicated air speed.

For more on the trip, the Sling and The Airplane Factory: www.airplanefactory.co.za

Come and Join Peter van Ket at the East London Surf Lifesaving Club as he launches his boat, the Nyamezela.

Peter is about to attempt a 5500km unassisted solo journey across the Atlantic and Aerontec are proud to be associated with Peter as the supplier of the composite materials they used to build this boat.

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These films are traditionally made from “nylon” and or nylon derivatives. Temperature capabilities vary from as low as 80°C to as high as 425°C. Certain types of resin systems, like phenolics, could have a negative effect on nylon films. If using phenolic resin systems, choose bagging films that are compatible with the resin system.

There are many sizes of bagging film from 75mm tube, up to 12m wide sheet.

Welcome to the new Aerontec website! We have been working on the site for the past couple of months and we are glad that today we can finally remove the covers and present you with our website!

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There are many types of release films, and like vacuum bagging films, vary in their capabilities. Release films are traditionally the most expensive part of the vacuum bagging stack. Release films are available in different perforation styles, depending on the application. P3 perforation is the most common.

Sealant tapes are a sticky type of butyl tape that ensures a good seal between the bagging film and the tool / mould surface. There are many types, but traditionally are classified according to the temperature rating. Good quality sealant tapes should stick well, hold the seal during the curing cycle, and then be able to be removed without leaving residue.

Peelply fabrics are normally a smooth, tightly woven nylon or polyester fabric. Other fibres like glass and Aramid are also used, but only for certain applications. If phenolic resins are used, it is advisable not to use nylon, but rather a polyester type peelply. It is important to remove the peelply fabric before the part / mould goes into operation. Peelply fabrics are there to impose a clean, uncontaminated surface ready for bonding or painting.

Breather fabrics are normally a type of uncompressed felt, also called spun-bonded, needled felt. Various types and thicknesses are available depending on the temperature, pressure and resin type. The breather aids in removing air and volatiles from the laminate, and transports them across the surface to the vacuum port, as well as allowing the vacuum to be dispersed all over the bag area.

Bleeder (to bleed out excess resin) is fundamentally the same thing, but separated from the breather by a solid release film. It is most common to use 1 fabric to do both functions.

Vacuum Infusion is a term used to laminate the part dry, and then allow the resin to flow into the dry fibres.

These materials are generally normal vacuum materials, with a few differences. There is no requirement for a breather or release film, but an infusion mesh that transports the resin inside the bag to the dry fibres, as well a re-usable silicone infusion track that disperses the resin. This is a simple process once you get the gist of it, but there are very definite considerations when laminating with core for example.

We will gladly assist in the planning of the infusion process and the placing of the various materials.

As with the vacuum film itself, there are many variations and careful consideration is required when choosing the correct equipment. Autoclave heat and pressure will collapse a pipe that is not constructed from the correct materials, as will normal vacuum at room temperature collapse an unsuitable one. Most vacuum pipes have a wire spiral either inside the tube wall or a separate one inside the tube. The ends require fittings that fit to the vacuum pump and to the bag.

Special quick couplers keep the vacuum “pressure” when separated on both sides of the coupling. These work very well with the “401 C” vacuum fittings (as shown in sketch), as well as vacuum gauges.

With infusion, we need cheap disposable lines (and no quick couples) as they will be filled with cured resin and be disposed of.