Designs

[gyourkoshaven]

The official rules are already out...

Changes: The plane can be constructed of carbon fiber and tape, along with the materials from last year (Wood, glue, etc.). New maximum horizontally projected stabilizer span is 28 cm. No maximum chord measurement for stabilizers. Only one propellor and one motor can be used per flight.

[blue cobra]

The official rules are already out...

Changes: The plane can be constructed of carbon fiber and tape, along with the materials from last year (Wood, glue, etc.). New maximum horizontally projected stabilizer span is 28 cm. No maximum chord measurement for stabilizers. Only one propellor and one motor can be used per flight.

Thanks!
Only one propeller and one motor? I didn't realize that was a problem last year, though that does sound like an interesting build...

[smartkid222]

carbon fiber? what would you use that for?

[jander14indoor]

carbon fiber? what would you use that for?

Stiffness. Can be useful, but not necessary. Example, a thin layer on top and bottom of a floppy motor stick will stiffen it up greatly. Adds weight, but can be compensated for.

Jeff Anderson
Livonia, MI

[smartkid222]

like the boron for f1ds?

[jander14indoor]

Basically yes, different in details, same basic principals though.

Jeff Anderson
Livonia, MI

[blue cobra]

Before I go buy a bunch of carbon fiber, could someone with the official rules assure me it is definitely in there, please?

Also, this doesn't seem like the place to discuss CF. Shall we discuss it in the balsa section?

[jander14indoor]

Whatever works on relocating conversation. It would make sense there, but the topics are only meant as guides to find info, not a straight jacket. No net cops here.

Jeff Anderson
Livonia, MI

[danyalukin]

Wing/tail chord.
MAX it! Wing area is good, more is better. There is a limit of course because as the aspect ratio goes down, drag goes up (thus elliptical wings become interesting), but its somewhere beyond 15 cm chord.

What is the aspect ratio, do you know how to calculate it, or do you know a good reading on that? We could just of course randomly try some sizes, but thats looking for a black cat in a dark room...

Considering the elliptical wing, what would those rations be?

thanks!

[jander14indoor]

Aspect ratio = span/chord higher is less drag, don't remember the exact formula for that, but it can be reduced by playing with the wingtips, thus tip fences. Elliptical wings figured on avg chord.

I don't have a hard and fast rule on how much chord is too much. As chord goes up, wing area goes up, lift goes up, flight speed goes down, drag goes down. But as chord goes up, drag goes up. Trick is to balance the two.

Base on past observations of good flyers when tail chord wasn't limited, I'd say an aspect ratio on the tail of 2:1 is doable, may be on the wing too, but only experimentation will tell. I know last year I saw up to 15 cm chord wings work OK.

Jeff Anderson
Livonia, MI