Build Thread for Whopper Flopper Chopper

[geof]

I did things slightly differently than might be shown in post #19. It was hard to tell from the photo.

In my photo below, my loop emerges from the outside face of what you call the outside rotor, through the standoff block. When I pull on that loop, it is difficult for the "inner" rotor to fully deploy because of the loop placement and the rigidity of the hinges (which is another problem I'm ignoring for now!).

I now believe that I should have made the loop emerge from the other side. Then, when it wrapped up and over the right edge in the photo, it would have a better angle for pulling the "inner" rotor out flatter. So, I plan to reverse the loops. Any thoughts?

 

[BABAR]

Regarding the reversed airfoils

Oh noooooooo
Sorry Jeff
If you want I'll mail you the original WFC. Just say the word.

Didn't know how much trouble I saved myself NOT doing the air foiling.
You probably already know this, but if you do cut and flip, you will have a weak joint if you cut straight across the grain. May want to consider either a 45 degree angle cut, or if that won't work, then an isosceles triangle cut (gives you an option of a direct flip.) And in case you are wondering how I learned this, it is because I have made similar boo boos before. I have also used it to splice rotors when I needed something longer than the 36" lengths I can buy at HL.

Whatever you do, try it on a scrap piece of balsa roughly air foiled first, to make sure it will actually come back together the way you think it will.

Just curious, any estimate of final mass/weight yet?

 

[BABAR]

I did things slightly differently than might be shown in post #19. It was hard to tell from the photo.

In my photo below, my loop emerges from the outside face of what you call the outside rotor, through the standoff block. When I pull on that loop, it is difficult for the "inner" rotor to fully deploy because of the loop placement and the rigidity of the hinges (which is another problem I'm ignoring for now!).

I now believe that I should have made the loop emerge from the other side. Then, when it wrapped up and over the right edge in the photo, it would have a better angle for pulling the "inner" rotor out flatter. So, I plan to reverse the loops. Any thoughts?

See diagram in post 9. In the diagram, the attachment point is the very tail END of the standoff adapter, which is part of the inside rotor. ACTUALLY attaching it there is impractical. Sooooo
What you have will probably work. But I think your plan for reversal is better. You will get a longer "moment arm" if you reverse the loops and have them coming off the inside face of the inner rotor (aka the upper surface of the tail rotor after deployment.) The longer arm means a longer transition distance between boost and deployed positions of the attachment point which means a longer CHANGE in the stretch of your rubber band. IMO the ideal position would be coming off the very tail ward edge of the rocket as shown in the cartoon diagrams, but that is impractical.

 

[BABAR]

Oh yeah,
You will probably want your knots to be on the inside surface on boost to keep them out of the airstream. I did that by poking TWO holes for each attachment point, starting from inside surface thread goes out to outside surface of standoff adapter, then back through the next hole to the inside. The knot is tied on the inside. The length of the string then goes out the "bottom" of the rocket, over the tail edge, and then back up toward the nose on the outside surface of the standoff adapter. Thus the knot and the origin of the loop BOTH come off the inside. Looks like you already have some tape over that tail edge. This is good--it prevents the pull string from "cutting into" the tail edge balsa.

Note for strength the two holes for each attachment point should be at least 4mm or so apart, and should pass through some tape on each side(reinforcement with CA may be an alternative?) Otherwise the attachment loop may cut or pull through the balsa.