markg0vbr
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- rawmarsh rotherham
A very small assist goes a long way.....
If you use a large strong motor to wizz you along quickly without much effort you need big heavy battery's which need a big heavy strong motor to pull them along.
A small light setup used to get you moving from a stop and give enough assistance so you are not straining week or damaged joint but is disengaged the rest of the time can give you an effective system.
http://www.lowtechmagazine.com/2012/10/electric-velomobiles.html for full article
"The eWAW that I drove has everything that the WAW has, plus an electric motor of 250 watts and a surprisingly small battery of 288 Wh, which takes you 60 to 130 km further (37 to 81 miles). The battery and the motor add only 5 kg, bringing the total weight of the vehicle to 33 kg. This is comparable to the weight of other velomobiles without electric assistance. Hence, this pedal powered Ferrari is more than 10 kg lighter than other velomobiles, with a 250 watt electric assistance, such as the hybrid Alleweder and the e-Sunrider, which weigh 45 kg.
Cycling at 50 km/h
So how fast is the WAW, and how much faster is the eWAW? First of all, the eWAW is a hybrid vehicle, but the biomass powered motor, also known as the driver, is not included in the package. Because the driver always provides the main part of the total power output, the speed of the vehicle will depend on the power that he or she can deliver. There is no better illustration of this than my test drive. Over a period of about an hour and a half, Brecht and I managed to reach an average speed of 40 km/h (25 mph) -- I was in the eWAW and had the regular assistance of the electric motor, Brecht was in a WAW without pedal assistance.
Cycling literature makes a distinction between three types of cyclists: people with an average fitness level, people with a good fitness level, and top athletes. Riders with an average fitness can maintain a power output of 100 to 150 watts over a period of one hour. Riding a WAW, this translates to speeds of 35 to 40 km/h in ideal conditions -- an unobstructed racetrack, and a completely closed vehicle. Drivers with a good fitness level can deliver 200 watts of power over a period of one hour, which translates to speeds of 45 to 50 km/h under the same circumstances.
With 250 watts of power, the electric motor of the eWAW gives a person with an average fitness level (like me) the power output of an athlete (100 + 250 watts = 350 watts).
Maximizing Range and Efficiency
I am a speed freak, so when I found myself on a nice, open stretch of road, the first thing I did was start the motor at full throttle and pedal like a madman at the same time. If I could have more than 350 watts at my disposal, I calculated, I must be able to reach speeds of at least 70 or 80 km/h (40 to 50 mph). However, my attempt to go any faster than 50 km/h (30 mph) left me frustrated -- the vehicle lacks the high gears needed for those speeds.
Why? Because the eWAW is designed for maximum efficiency. The electric motor is intended to be used for acceleration only (and for climbing hills). Once the velomobilist reaches a cruising speed of about 40 to 50 km/h, he or she switches to pedalling alone.
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The engineer's choice to assist the driver only during acceleration is smart; it increases the range of both the cyclist and the battery spectacularly
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The eWAW does not increase the cruising speed or top speed of the unassisted WAW, although it does increase the average speed because it speeds acceleration. This is a different approach from the electric bicycle, where pedal assistance is continuous at normal cruising speeds. With regards to efficiency, the concept behind the eWAW makes much sense. A bicyclist needs less energy to accelerate than a velomobilist does (because of the bike's lighter weight) but more energy to keep up speed (because of its weak aerodynamics). In contrast, a velomobilist needs more energy to accelerate than a bicyclist does (because of the vehicle's heavier weight) but less energy to keep up speed (because of its excellent aerodynamics)."
