Human/Electric hybrid velomobile?

[Malcolm]

Jeremy, the heat-shrink Dacron skin over frame sounds good. It should be relatively quick and clean. Certainly good enough for prototyping. I'm not too keen on glass fibre and resin personally. I just don't find it much fun doing anything that involves wearing gloves and a face mask, but there's no disputing the quality of the results you can get.

Mik: Thanks for your informative and impartial description of the different methods. I actually stumbled across Montford's geodesic airolight designs yesterday and was impressed with the kevlar tape idea to provide torsional rigidity. That's obviously not a problem anyway with a plywood skin, and like you say it does both jobs well.

 

[fechter]

Welcome loftyendeavors,

The fuel cell is cool, but only makes 100w @ 12v.
Depending on your speed and aerodynamics, the vehicle would probably use substantially more than 100w.
It would extend range, but for that price it would be better to just buy more batteries.
Solar panels are sort of the same problem. They would be great for recharging while parked all day, but for supplementing power while riding, the benefit is marginal unless you have a huge set.

 

[Jeremy Harris]

Another of my hobbies is flying, and I've dabbled in designing light aircraft (see: http://www.realityaircraft.com for one that I had a fair part in designing, and which uses fabric covering). Heat shrunk Dacron is definitely worth considering and is really pretty simple to do. The only thing to remember is that the edges of the structure have to be pretty strong to resist the tension from the fabric. For something that's primarily just an aerodynamic fairing then an airship-like design would probably work well, with the fabric only attached to the longerons/stringers, not the ribs, which would be best inset slightly from the skin.

I've also looked at fuel cells, but they are pricey and a bit inconvenient if they use hydrogen. If the price of the methanol fuelled ones was to drop, then a small one might make a suitable on-board battery charger. Such a gizmo might be a way to charge a battery up whilst at work, though.

Jeremy

 

[loftyendeavors]

What power fuel cell do you reckon would be realistic for pushing or extending the range of a bike by lets twice?

 

[Jeremy Harris]

This depends very much on the average power consumption of the bike/velo, which depends very much on average speed, terrain, type of tyres fitted, all up weight etc.

For a typical upright, two wheel bike, ridden at an average speed of 20mph on level ground, the power consumption is going to be around 340 watts. If you had a battery capable of running this bike for one hour, so giving a 20 mile range, then it will have delivered about 340 watt/hours.

If you wanted to double the range to 40 miles, then you would need to provide a total of 680 watt/hours. The battery on it's own will deliver half this, so the fuel cell will need to deliver the other half, in other words, it will need to put out a steady 340 watts for one hour to double your range.

The figures would be a lot lower for a streamlined velo on level ground, but hills would up the numbers a fair bit.

Jeremy