Oct 7

October 7, 2005

Over-the-shoulder top bar, new seat and more testing

you know the drill - click on the little picture to see a big one. Or what ever.

What took me an entire day to make, took about 10 minutes to destroy. My seat came off quite easily - much to my happiness, and also much to my dismay. It should not have come apart that easy - my add-on carbon wasn't bonding to the old carbon like it should. I'll have to start paying more attention to how the surface is treated first - sand it to make it rough, then clean it well.
I decided that rather than building a new seat, I can scavenge the nice carbon seat from the rocket velomobile since I have stollen other parts from it for CP.
I bent up a couple of aluminum brackets that worked like crap. They look like they should work well, but are flexy like crazy. The seat wobbles back and forth. I decided to cover them with a few layers of carbon to see if they will stiffen up. I like the fact that I can raise or lower the seat back angle. So CP1 is still convertible to a camera bike.
I removed my temporary steel weldment and was very surprised at how much twisting flex the frame had without that top bar in place.

I put new over-the-shoulder bar on the right hand side - opposite the clam shell door on the left.

The nice thing about working with composites is you are not restricted to shape. It took me about 20 minutes to carve out a suitable form for the bar. I glued layers of foam together using hot glue, then hot glued the form to the frame.

I wrapped a few layers of carbon fabric + wound a strip of carbon unidirectional tape around it. Then I wetted it out with epoxy resin and mummified it with multiple layers of tight cellophane.
I poked holes in the plastic wrap to allow the excess resin to bleed out.
I was pleased with the result, and it was WAY stiffer than the temporary steel bolt-on.
I also covered the seat brackets with a few layers of carbon. The seat is stiffer now, but not as stiff as I would like. I also added a layer of closed-foam high density foam (the white layer) + a thick open cell cushion on top (black). VERY comfy!!!
One of the benefits of buying a TIG welder and learning how to weld rather than relying on brazing. I can't count the number of times I didn't have a fastener or other small simply part that didn't fit. It is so easy to simply weld-up a bolt to the exact length required - takes about 2 minutes including turning the welder on, un ravelling the cables and actually joining the two parts. I needed this longer bolt to pass through the thick shoulder bar to hold the fairing door hinge into the frame.
I got Angle to micro-fill and sand down the holes where the windows used to be. This is still just a 'work fairing', but I still want it to be as smooth as possible.
I am happy to say that I was able to do 2 hours straight on the Glenmore track today.

The new seat and position is super, super, super comfortable. It's different though - all of my training to date has been on a lower seat back angle position, so this new position is introducing some slightly different muscles. After a 5.5 hour total riding in the new position today, I find my gluttes are feeling it a bit.

This 2 hour simulation was very good for me today. A chance to get used to going around in circles and being cramped up in the streamliner. There is NOT very much room in there! now that my head pokes through a little hole in the roof, I barely have room to move my hands around. Eating and drinking are going to be a challenge.

I used John Snyders PWRDRAG2.xls nifty little spreadsheet to calculate my rolling resistance and my drag again. It works on the principal that at high speeds, aerodynamic drag is a larger resistor than rolling resistance is at slow speeds. You input 2 sets of watts / speed data, one high speed and one low speed. It estimates what your CdA (aerodynamic drag) and Crr (rolling resistance) is.

Here is what I got:

High speed: 124 watts, 35.6 kph
Low speed: 94 watts, 29.18 kph

CdA = .47 (sq ft)
Crr = .0104

The Crr seems very high, but that may be accurate because of two factors: First, the surface of the track is very soft rubber. You can depress it with your finger. And second it was only 7 degrees C. The colder the temperatures are, the higher your Crr. I previously measured the Crr on a warm day on a flat and smooth road at around .0058

Above is a comparison of the two seat positions. Note the new skater helmet - It's more lowracer friendly because there is not pointy thing in the back.

To do now:

1. Build retractable landing gear
2. Build a window for the nose
3. Fit and securely fasten fairing into place, then cut a removable door for self-entry/exit. I'm thinking a simple hinge at the top would work
4. Make THIRD fiberglass plug for body work
5. Finish micro'ing rear wheel fairing attachments
6. Test out the new windows / pan cam
7. Make new seat
8. Replace steel 'over the shoulder' support with carbon
9. Make PETG bubble

Cockpit management:
1. Someplace to attach 2 water bags, one with water and one with liquid calories
2. Radio (walkie-talkie) - microphone, push to talk switch on handle bars, somehow incorporate into iPod headphones?
3. Ipod mounting place (control?)

To do eventually:

6. Build a new fairing mold from the new plug
7. Pull carbon fairing shells from the new mold
8. Build proper SEAT!
9. Mid-drive lightening holes (James Kenny)
10. New carbon fork?
11. Add a thin coat of epoxy to the left hand wheel disc because it is not air tight
12. Carbon wheel disc for front wheel (or buy a 650 disc wheel)

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