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Old 05-19-2020, 02:53 PM   #327 (permalink)
Bicycle Bob
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Join Date: May 2008
Location: N. Saskatchewan, CA
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Appliance White - '93 Geo Metro 4-Dr. Auto
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Quote:
Originally Posted by The Toecutter View Post
<snip> What was your intended price point were it to have been put in production and at what year? How much do you think something like this could be built for today, in terms of dollars for the parts, dollars for the use of tools, and how many hours of labor?

A: I was expecting to price them for $5,000 in 1990, by selling molds to regional producers of kits for local assembly. I have not done any recent estimates, but the usual tradeoff between investment in tooling vs providing jobs is quite applicable, as are economies of scale.

<snip> If you can, you should definitely build a new one and use it as a daily rider, just to show what kind of reliability can be had with the design. Prove the concept works, is usable on an everyday basis, and is reliable by racking some miles up on it.

A: Sadly, to maintain a workshop, I moved to an area of no commuting. I walk to stores and ride for exercise, seen only by farmers and occasional cottagers. I might build a version that can be built from plans instead of molds, though. Still, there are many velomobiles on the road showing practicality, and it would take a multi-talented team to add mass appeal to any design. My specialty is reducing the parts count. If I were going into business today, I would produce components for trikes first, to take 5 lbs off the usual adaptations from bicycling. With revenue from parts, we could work on the rest.

Q: Coroplast is a good material for a prototype body, but it does not lend itself well to long-term use without those cosmetic issues developing. Over a long period of time, it sort of begins to behave like a liquid instead of a solid, and any load-bearing pieces will begin to warp and lose their stiffness. The first coroplast shell I made lasted almost 2 years before it started developing a harmonic wobble during high speed riding that turned what used to be a stable vehicle at speed into a nightmare to control at speed, and this current coroplast shell I recently posted a picture of uses aluminum braces bolted to it to stiffen it. I'm hoping it will last long enough for me to build a permanent shell, since this coroplast shell was made just to get the shape right, since the first shells aerodynamics left a lot to be desired and had other issues. I'm going to move onto either fiberglass or carbon fiber and make a compound-curved near-replica of the shell out of such, once I get the aerodynamics, ergonomics, and clearances the way I want them.

A: My link includes details on a much lighter Coroplast body that turned out to be astonishingly rugged. I have never had trouble with stress points creeping, but I'm pretty fussy about local reinforcing. I think that there is a lot of potential for vacuum-formed Coroplast, but I really prefer John Tetz's use of semi-rigid foam instead, because Coroplast is so noisy with road rumble. Perhaps isolation mounts would cure that, but that adds structure and weight. The foam would need a thick Urethane paint to look shiny.

For regular use at highway speed, I'd like to try several layers of coroplast strips, laid up like a molded plywood boat hull but without the careful edge butting - more like a non-woven basket. Basic silicon seal at each crossing makes a good bond, and the holes let it cure. Then a light coat of foam and 'glass gives a slick finish over a full-body helmet. Carbon is the wrong way to go - a fairing needs toughness since it can't afford the weight of total invulnerability.

Q: After that, I'm going to give building a fully custom steel chassis with full suspension a go, and build a pedal/electric/solar velomobile/sports car hybrid completely from the ground up. The goal is a total finished weight of around 100-120 lbs, capability of safely holding highway speeds(DOT wheels/tires), acceleration from 0-60 mph in under 5 seconds, top speed around 100 mph, light/efficient enough to be pedaled faster than an ordinary bicycle with the drive system shut completely off, operable as a pedelec or with throttle, 20 Wh/mile @ 70 mph with 150W rider input, ability to hold 1G lateral acceleration without tipping over, small enough to fit in a bike lane(< 40" wide). a 2 kWh battery pack, and a 100W or larger solar array built into the body.
I like it, but I'd like it more with integrated frame and suspension. Why build something rigid when flexible is lighter and more functional? It could be done in steel, but you'd have to really enjoy advanced metalwork.

1g lateral sounds wonderful for conserving momentum, but in the real world, you seldom get to use it without bothering people. To stay narrow for filtering and passing man-doors, I'm seriously tempted by the complications of a tilting mechanism. In any case, I think that .6 g is sufficient. It has the advantage that you can practice approaching it frequently, and those reflexes are probably better than ultimate performance in a sudden crisis. You get much less rolling resistance with relaxed traction demands, too.

I would also recommend paying serious attention to directional stability. With such a light, fast, streamlined form, traction becomes unreliable. Aim to have a stable glider fuselage that usually stays on the ground, but does not yaw in a crosswind gust, even on wet ice. It just moves over.
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