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Power Trailer 1
Power Trailer 2
Power Trailer 3
Power Trailer 4
Power Trailer 5
Power Trailer 6
Aero   view 1
Aero   view 2
Aero   view 3
Aero   view 4
Aero   view 5
 Calculations



Wattage calculations:

Bearing and tire friction =   .02  x  speed  x  weight

Air resistance =              .1   x  (speed x .45)^3
( .1 is a reasonable
coefficient for the
trailer/bike combination
with or without the 
aerodynamic tweak.)

Motor heat loss =              30%  of draw


1.  No cargo  

Bike and rider = 200 lb
Trailer        = 400 lb
-----------------------
                 600 lb


               watts   watts       watts      watts
             friction   air        total      drawn

10 mph         120      10          130        185
20 mph         240      70          310        445
30 mph         360     250          610        870
40 mph         480     580         1060       1515


2. 900 lb at full cargo

10 mph         180      10          190        270
20 mph         360      70          430        615
30 mph         540     250          790       1130
40 mph         720     580         1300       1860



The two motors combined draw up to 2000 watts.

The three batteries combine for 3000 watt hours
at a draw of 56 amps (672 watts).

Our tables above indicate that that would allow
22 mph with a 50 lb cargo load for 4.5 hours,
yielding a range of 100 miles.

The batteries combine for 2700 watt hours at a
draw of 75 amps (900 watts), allowing 29 mph 
with a 50 lb cargo load for 3 hours, yielding 
a range of 85 miles.



Top speed based on sprockets ratio and motor rpm:


Motor rpm = 2600 no load

Drive sprocket = 1.23" diameter

Wheel sprocket = 2.67" diameter

This produces 44.5 mph top theoretical speed,
no air resistance, no friction.

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I will not be building this trailer until spring
of 2009.  If you build it first, you will be a
pioneer.