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Electric Flight in Australia
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Powerhouse by Kevin Johnson
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Kevin's Powerhouse specifications:
- 2.1m wingspan
- 2.5kg weight
- Graupner 700BB neodyn motor
- Graupner in-line Speed Gear 700 gearbox
- 15 x 6 prop
- 6,000 rpm on 8 cells
- 8 - 12 cells
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- Powerhouse by Kevin Johnson
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- Most electric old timers are scaled down versions of the original, but not Kevin Jonson's Powerhouse! Kevin, who hails from Lismore on the NSW North Coast, built a full size model and finished it in "old worldie" sepia tones. It looks very authentic in the air, topped off by all the usual Old Timer trimmings, like Trexler pump-up airwheels.
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- For power Kevin turned to the very economical and under-rated Graupner 700BB Neodyn motor. Even the ferrite versions of these motors will give outstanding performance. The motor can be supplied with an in-line 2.7:1 Speed Gear gearbox fitted, and this is the unit that Kevin chose. This is not a planetary gearbox; instead it uses an idler shaft within the gearbox housing to transfer the thrust to a separate main output shaft which is mounted on twin ball-races. The idler shaft runs in twin needle roller bearings. Another alternative is the 2:1 belt-drive unit which accepts the 700 motors. I used one of these very effectively in a 4m wingspan glider where space was not an issue.
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- Kevin's Powerhouse flies very realistically on only 8 cells. It looks like a real Old timer climbing out slowly at a steep angle of attack. For more lively flying, Kevin changes to 12 cells.
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- Try a full sized Old Timer yourself. Electric power adds another dimension to this popular branch of our sport. Today the ready availability of low-cost outrunner motors and the success of LiPo batteries outdate Kevin's successful set-up - my suggestion would be either a Scorpion 3020-16 outrunner on 3S swinging a 14x7" prop for adequate power or a Scorpion 3026-10 on 3S with the same prop for more lively performance.
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