March 25, 2006

The super canopy machine and stiffening ribs for the streamliner fairing shells.

I was playing around with making a new canopy bubble for CriticalPower because the old one is pretty scratched up from the Alabama record attempt. Also, we had to cut a hole in the nose of the old one in Alabama because it was fogging up so it’s basically garbage.

I was using the old Varna canopy mold and noticed that my best canopies were always the ones in which I stopped the vacuum pull just before the PETG touched the mold surface. Then I realized that the actual mold wasn’t really doing anything aside from providing a sealed cavity for the vacuum to pull the hot plastic down.

After I realized this, I figured that I could make a new mold which would be simply a larger sealed box and I could make a canopy bubble as large and as deep as I needed by simply controlling the heat, the angle at which gravity and the vacuum was pulling down on the hot plastic, and the amount of vacuum pressure.

We (by ‘we’ I mean Ben) built a plywood box with a new longer canopy bubble shape cut out of the top. The PETG sheet is sandwiched between another cutout and my infrared heaters go to work and melt the plastic sheet.

There is a 1/4 inch hold drilled into the bottom of the box where my venturi vacuum hose is connected. When the plastic starts to get soft, I turn on the vacuum valve and start to pull the hot plastic down into the box.

I stretched an elastic band across the box about 3 inches up from the bottom to use as a marker to know when to stop the pull.

The canopy bubbles were absolutely perfect – far better than anything I had ever made previously with the old mold. They are optically clear and perfectly smooth.

This is the shape that the bubble was always meant to have – see how nicely
it tapers into the rear tail? Far, far better than before.

This shows the old canopy bubble under the new super bubble. You can see
how much longer and aerodynamic the new one is.

Since I am using 1/16″ thick PETG, it is getting way, way too thin at the top of the bubble. I am going to have to switch to a 1/8″ sheet.

Stiffening ribs for the Critical Power fairing shells.

We laid the fairing shell back into the mold, and cut out strips of coroplast and contact cemented them to the inside of the shell in a criss-cross pattern. Then we spray glued 2 layers of carbon over the coroplast ribs, wetted out with epoxy resin and vacuum bagged.

The result is fantastic! VERY, very stiff shells and WAY stronger than before without much weight added. So strong that I could stand on the shell now without it deforming.

The shells are so stiff and strong now, that placing them onto the frame is a snap – no need for alignment pins. It is now a one-man job which is great. The plan for the next record attempt is to have me stay in the streamliner for as many pit stops as possible. We are going to move the water and nutrition ports up to the top so my crew can easily re-fill me while I stay in the vehicle. If I need to get out to stretch, then it should be an easier job of removing and then replacing the left hand shell.

Here is the new TODO list:

1. Communications! – I ordered 2 Chatterbox GMRS-X1motorcycle two-way radio systems from HelmetCom. These babies will let me plug in my iPod AND cell phone and use them seamlessly with the two-way radio.
2. Fast entry/exit – we are moving the food, water and battery access areas to the top behind the canopy top so I don’t have to get out every time we need to refill water, food or replace the battery. I might plan on getting out every 6 hours or so rather than every 3 hour interval pit stop.
3. Fairing ribs – Done.
4. CHAIN GUIDES!!! – Done – I made some chain guides out of plastic tubes, but forgot to take pictures.
5. New clincher wheels – I found a RENN 650 rear clincher on Ebay and the same seller was offering a 700 HED 3 carbon rim front wheel so I bought them both. I’ll simply add my carbon wheel discs to the HED, and the RENN should be good to go.
6. Fairing paint and polish – We need to coat the fairing shell with a thick epoxy based primer and sand and polish it smooth. This will seal up all the pin holes and hopefully improve the chances of obtaining some laminar flow.
7. Wheel shroud for the front wheel – this was something that I had meant to do originally, and never got around to it. Since my front wheel is surrounded by the carbon sandwich board frame, building a carbon envelope for the front wheel shouldn’t be that difficult.
8. Rear wheel fairing shape – We’re probably going to smother that rear wheel fairing with expanding foam, then carve out a nice shape and carbon over it.
9. New Canopy bubble – Almost there. I need to make one with thicker PETG.
10. Canopy bubble nose lifter – I need to invent something to lift the front of the bubble up about 1/4″ to allow the airflow to evaporate any condensation that may build up on the inside of the canopy. The was a problem in Alabama when it got cold at night and we had to cut a large hole in the front of the bubble.

Critical power is human power!

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