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April 23, 2019, 04:32:58 AM *
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Author Topic: Scale up/ down and power requirements  (Read 112 times)
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« on: April 06, 2019, 05:58:02 AM »

Recently built a Scarab (A Hatful 1947) free flight.  Scaled it up a bit -25% - for modern 049 engine.  But heres the question:
25% increase on span is +50% on area and double the volume.  Assuming weight follows volume, more or less, then what power might we need?
Redfin 049 vs original specified Amco has double the power.  Another popular motor backalong was the E D Bee but it has a third of the power of a PAW 1cc, so a modern engine will help.
My Scarab power to weight ratio is exactly as the original, by chance rather than design and flies very well!
If anyone has any more sophisticated calculations, I would be most interested, thanks.
OnYouTube is a giant Scarab - 84 inchspan with an OS 70 on board...... looks overpowered to me.
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