View Single Post
  #3  
Old August 11th 06, 04:06 AM posted to rec.aviation.homebuilt
UltraJohn
external usenet poster
 
Posts: 8
Default Electric motor for hang glider

Legend Length wrote:

snip


I am unable to find electric versions of those powered harnesses being

sold. Looking around for battery prices I found this site:
http://www.hobby-lobby.com/flightpower.htm . The last battery on the
page is 22.2 V, 7.4 Ah = 164 kWh. I thought it may be interesting to
see how they would hold up when powering a human aircraft.

snip

So it appears from my very rough calculations that you can achieve
around 3 kW for half an hour of flight, for $5000 and 5 kg of
batteries. Is this an unrealistic base line for me to use, before
adding the weight of battery heat insulation and other things?



Two things:
1. that would be 164 wh not kwh it would be .(point)164 kwh.
that times ten would give you1.64 kwh or 3.28 kw for a half hour so your
3kwh figure was ok.
2. you really need to research how the battery holds up to deep discharges
and how well the recover. also how many cycles can they handle? $5000 is a
lot for a battery pack and if in only last 10 or 20 charge cycles you'll
need to win the lottery to be able to fly it! ;-)
I personally am not familiar with that battery so can help you much there
John