GeeBee Varna streamliner construction - Garrie Hill

GeeBee Varna Streamliner Construction

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11/07/02
When we last left our Intrepid Carbon Constructor, he was preparing to lay the inner layers of carbon on the bottom tub. Have no fear! All things went well, and he now has a tub weighing in around six pounds capable of supporting a wife and four kids! No pictures, because it looks no different to the camera. Let us now rejoin the action...

The GBV molds are made in three parts: bottom tub, left top, right top. Why a two piece top? Several reasons. Foremost is the depth. A one piece top mold would mean that you would be laying your composite shell into a narrow, deep trough. Trying to get everything to stick to the sides of the mold
would be difficult! Not to mention the problems of custom making a vacuum bag with a re-entrant shape. So, you use a left half/right half mold to simplify the whole process. Instead of one mold 17" wide and 20" deep, you have two molds each 8.5" deep and 20" wide. Much, much more manageable.

The fairing top

You know the drill from the previous page, so here goes: These two pictures show the dry carbon fabric cut pieces placed in the mold.

Using the 3M Super 77 spray adhesive, Išve smoothed and lightly tacked down the dry fabric.

Using the Vacuum Bagging 101 process, this shows the mold, carbon wetted with epoxy, nylon bleeder, and polyester breather in the vacuum bag ready for the vacuum pump.

Just to show you a close up view of what the vacuum pressing does: This picture is a view of the nose area with no vacuum

Next we have the same area with the vacuum turned on. You can just see some of the excess epoxy starting to be squeezed through the nylon bleeder into the breather.

This shows the area around the vacuum fitting. Just to give you an idea of the forces involved, I can normally pump down to 22% of one atmosphere of vacuum. This translates to over 3/4 of one ton per square foot. I will leave the conversion to metric as a math exercise for the English impaired! Suffice to say, itšs seriously squished.

The outer skin after curing and debagging is ready for the next step. If you look closely, you will see a black line marked parallel to the left (picture left) edge of the skin in the mold. This is the layout line for placement of the Nomex honeycomb strips.

Here's the honeycomb strips spray bonded into place. A hint for anyone needing to cut this stuff without shredding it. Use an electric carving knife. It does a whizbang job, super clean cut (as you can see). For marital harmony, buy your own knife! Don't use the wife's!

A view of the fabric draped over the honeycomb, ready to be doped.

Close up views of the ribs after debagging

The right half, out of the mold and ready for the next step.

...and herešs the right half positioned on the bottom tub.

This shows the relative position of the seat (also carbon) in the fairing.

And here we have a front and back view of my carbon fiber "wishbone" seat, which I make available to homebuilders.

Next page: Completed bike