What is it made of?

    A Velocity is built utilizing materials and technique pioneered by Burt Rutan for his construction of VariEZ called mold-less composite construction.  You can think of it as a sandwich.  To create structure like a wing, you start with a foam core.

     You then cover the foam with a few layers of fiberglass cloth and then saturate the fabric with epoxy resin.  When the resin cures, you end up with structure that are light but very strong.  For many of the load bearing surfaces, you'd add solid fiberglass spar for additional longitudal rigidity.  Some areas of the aircraft, like fuselage is built from foam sandwich that are created in a mold at the factory.  These ensures that the parts are consistently formed and cured.

     In general, the kit is put together by joining major components that are constructed as above using additional fiberglass and epoxy.  It is not unlike assembling those plastic model airplanes by gluing the pieces together.  In most structural applications, the "gluing" is done by overlapping layers of fiberglass layups that are cured in place.  A common misconception in this process is that it is the epoxy that creates structure in a layup.  Thus, in the time honored tradition of "If you are not sure, add more to be sure." principle, builders frequently add more epoxy in a misguided belief that it will make the part stronger.  It doesn't.  It just makes it heavier.  There are two major factor that affects the strength of a joint.  The amount of the fiber and the contact surface bond. 

    First, the more glass fiber is available to bear the load, the more the layup can support.  Sounds straight forward, doesn't it?  The key words here is "available to bear the load".  The fiber is the strongest in tension and weaker in shear and just about useless against splitting load.  In most situations, the joint must bear loads that comes from multiple sources and in many directions.  A commonly used fiberglass cloth addresses this issue by weaving fivers in cross-hatch pattern.  These are often referred to as "BID" for "bidirectional".  In constructing an aircraft, the layups involving bids are always done in 45 degree bias against prevailing load axis.  This is so that the maximum number of fibers are 'working' at all times.  When additional strength is needed, thicker cloth with additional weave is used called TRIAX (triaxial) is used.  These create heavier structure and are used for critical structural areas like gear, canard, firewall, and main spar attachments.

     The second factor, surface bond, is equally important.  A layup is only as strong as the underlying bond.  This bond may be against another fiberglass structure or may be against another material.  In either case, if the bond is not strong enough, the layup can fail prematurely.  Here is another area of a common misconception.  Many believes that there is a chemical / molecular bond between existing surface and the newly created layup.  The reality is that the bond is purely physical.  In other words, the epoxy needs rough surfaces to "grip" onto.  The rougher the surface, the better bond you will achieve.  This is why surface prep is very important before a layup.  The common process is to 'rough-up' the surface with sand paper or other method prior to layup

     The surface contamination is another factor that can substantially weaken the structure.  If the joining surface is contaminated with grease, oil or paint, it will interfere with the epoxy achieving proper physical contact with the underlying surface.  This is the reason why we wash / wipe the surface with de-natured alcohol or MEK prior to layup.  Something to note is that the factory uses mold release agent for the pre-molded components.  This means that any factory produced fiberglass parts must be cleaned prior to any layup can be done.

    Once you get the knack for it, fiberglass can be an extremely versatile medium to work with and it is relatively simple to manipulate.