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Old 09-01-2004, 11:42 AM
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airhead
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Default RE: Converting Seamaster .40 to Speed 400

In attempts to take advantage of the park down the street from me, I have started embarking on a quest to shrink a .40 sized seaplane down into a Speed 400 electric seaplane.

I spent a day doing some calculations and have found that by scaling the plans for this plane down by 50%, I should be OK. It takes the wing area from 667.5" to 166.875" and keeps the aspect ratio the same (4.6354:1). The area is 25% of the original size (with the span and chord 50% of the original size). Thanks to Kinkos, I now have a scaled down set of plans.

Do some research on the web, I came across this site (calculator): http://www.csd.net/~cgadd/eflight/calcs_gloconvert.htm

The chart states that a wing loading of 15 ounces / square foot is good for trainers and 20 ounces / square foot is good for sports planes. I would say that the seaplane I am looking to convert would be somewhere in the middle of a trainer and a sport plane. This has me shooting for a wing loading of about 17 ounces / square foot.

This would mean that I would need to come in at a weight of about 19.2 ounces (@ 1.2 pounds).

Now for my questions:

1) Do these calculations jive?
2) Are there any gross errors that I may have made?
3) Where are the best places to save weight when building?
4) Should I shoot for 1/16" sheeting over 1/8"?
5) Should I use stringers over sheeting?
6) What kind of covering?

Thanks - I'll keep any parties interested in this kind of weird conversion posted via this thread.

Dan