Rotors

[aubrey048]

my partner organizes and numbers all of her wood by density. It seems like a lot of work, but it pays off when building.

That's brilliant! *taking notes*

[thewinner]

Yeah, I just started doing that. It was really surprising how much variation there was in a batch of balsa.

[chia]

-nod nod- Yeah, I'm almost always more organized than actually necessary . For 1/16x1/16 pieces, I grouped them into four categories based on mass, because it would just take forever to do it individually (I bought it in bulk one time and have lots left), but I had 8 motor stick sized pieces of the same length which ranged from 2 grams to 8 and everything in between... so I figured it was probably a good idea to label them so I'd remember.

[illusionist]

Do hobby stores give you discount if you buy in bulk? Cause I would love that. Last time I went they had the crapiest balsa... Maybe I should learn to cut my own 1/16 x 1/16

[thewinner]

If the balsa sheets are crappy, won't you have bad wood anyway?
But yeah, I wish I got discounts on balsa.

[kjhsscioly]

Do hobby stores give you discount if you buy in bulk? Cause I would love that. Last time I went they had the crapiest balsa... Maybe I should learn to cut my own 1/16 x 1/16

It is actually really easy. C-clamp a metal ruler to the table, over a sheet of balsa. you can measure or eyeball the distances, and cut with a sharp blade.

[illusionist]

Okay, I just tried it out with 1/32 sheet balsa, and it worked quite well! Tomorrow I'm going to go out and get a sheet of 1/16 and I'll try it out. I don't have a ruler long enough, but I'll find something else.

[wlsguy]

I would buy a "master airscrew balsa stripper". It is the cheapest balsa astripper available but works pretty good. Many hobby stores have them.
Because it's plastic, it will eventually become loose but at $5.69 from Amazon, just buy another one.

You can then take your scale with you to the hobby shop and weigh each sheet of wood before you buy.
It's much cheaper than buying sticks individually.

I know this should probably be in the "Building Techniques" forum but, since people were already discussing balsa stripping, I thought it would be ok

[illusionist]

That one actually seems extremely easy to use. I'll ask my coach if we can purchase one for the team.

[illusionist]

Well, I've gone from having a 1.26 gram fixed rotor, down to building my latest rotor: 0.56 grams! (Both of them with covering).
So the helicopter ends up at around 3.5 grams. Should I use some of the weight to use stronger spars for the rotors? I haven't yet done a test flight, so I am unsure of the performance.

[chia]

NIce! That final weight is what I was aiming for, but it ended up around 4.04 because of the motor stick >.>
How would you go about making the spars stronger once you've built the rotors? Just glue, or reinforcement wood, or what?
Either way, unless they're made of really weak wood, your rotors should stand up fine against anything and probably won't warp much in flight. I would use some of that extra weight for ballast at the bottom. Balance the whole helicopter on your finger on the motor stick... is the center of gravity halfway up or more? Even if it isn't, ballast at the bottom can't hurt.

[illusionist]

Thanks! I found one motor stick that is perfect, and I can't find another one like it (I hope it doesn't break).
I meant to make them stronger the next time by using denser wood for the spars. Right now, they bend somewhat when I blow on the blades, so I'm worried about warp during flight...
As for ballast, I will definitely put it as close to the bottom as possible.

[lllazar]

My motor stick is insanely strong and it weighs like 1.8 g. But my rotors are light enough that copter is like 3.75g without clay.

Btw do u guys attach the clay before flight and then remove it afterwards? Clay loses mass due to the water evaporating to form equilibrium with the atmosphere.

[kjhsscioly]

We have this clay that came with my Wright stuff kit last year. It is some special stuff that doesn't lose any mass over time, and stays wet indefinitely.

[thewinner]

Yeah, I have some of that stuff too. But I'm not sure where you get more of it.