Friday, May 31, 2013

No Fiberglass Milans only higher tech fabrics(maybe)

This is a define possiblity.  I am evalulating some new materials that could displace glass in the Milan.  The primary advantage will be its lower density(lighter parts) and secondarily that it can be made in a very sustainable manner.  The material is derived from wood waste in Western Canada.  To make it even a little more interested it was developed locally.  Previous greener fibers for composites have had much lower perfomance than glass at substainally higher cost.  The new cellusoe derived material is priced better and has perfomance much like glass.  In the photo you can see a set of samples laminated up.  The near one is about the present laminate in the Milan GT while the back one is the new material and some new material combined with Kevlar. 
The problem with designing a laminate for velomobiles is the very flat shape from the wheel well area to the tail.  The laminate needs to be stiff enough not to vibrate but it can't be very heavy.   One can add a reinforcing rib inside or modify the shape to make it stiffer.  Both are not optimal solutions if looking for the best aerodyaminc shape and least weight.  At first glance a cored laminate might be the solution.  Unfortunatley by the time you add the core you have the weight of three layers of fabric.  A core like this with very light skins on either side is very likely to print through the skin.  You will see in quite readily on the outside of the shell especially after a few years.   The strip of Kevlar in the near laminate was my solution to the stiffness/weight issue decribed above.   The bit of Kevlar in the far laminate should add some stiffness and increase the impact resistance of the velo. 

Saturday, May 18, 2013

Two of Three

Two of the three moulds for the shell of the Milan SL are now made.  Just one to go.  Once it is laid up I will let the moulds sit together and cure for an week or two.  There are lots of other moulds to be made.  A partial list is left and right wheel wells, rear fender mould in two version one for suspension and one  without, the front storage tray left and right, door, and covers for the chainline.  In addition new ribs for the floor will have to be designed and moulded.  At least I now know what is required from the experience building them for the Milan GT. 

Saturday, May 11, 2013

Milan SL Progress

Have made some progress on building the moulds for the Milan SL.  The top mould is built and now started on fitting the flange to divide the bottom into two parts.  This is necessary so the parts can be removed from the mould. 
I am glueing the flange on with hot melt glue so there is no need to make holes in the pattern. Makes moulding the other half easier.