Rotors

User avatar
kjhsscioly
Exalted Member
Exalted Member
Posts: 517
Joined: January 16th, 2009, 11:55 am
Division: Grad
State: IL
Location: Chicago

Re: Rotors

Post by kjhsscioly » April 8th, 2011, 5:26 pm

illusionist wrote:Do hobby stores give you discount if you buy in bulk? :D 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.

User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI

Re: Rotors

Post by illusionist » April 8th, 2011, 6:00 pm

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.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

wlsguy
Member
Member
Posts: 366
Joined: March 23rd, 2009, 9:08 am
Division: Grad
State: OH
Location: Ohio

Re: Rotors

Post by wlsguy » April 8th, 2011, 6:58 pm

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

User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI

Re: Rotors

Post by illusionist » April 8th, 2011, 7:04 pm

That one actually seems extremely easy to use. I'll ask my coach if we can purchase one for the team.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI

Re: Rotors

Post by illusionist » April 10th, 2011, 7:40 am

Well, I've gone from having a 1.26 gram fixed rotor, down to building my latest rotor: 0.56 grams! :D (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.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

User avatar
chia
Member
Member
Posts: 558
Joined: January 13th, 2009, 5:09 pm
Division: Grad
State: IL
Location: Derse

Re: Rotors

Post by chia » April 10th, 2011, 8:39 am

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.
(avatar is by xamag)
Favorite events: Anatomy, Microbe Mission, Ornithology, Circuit Lab, Helicopter
NCHS '13
==>

User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI

Re: Rotors

Post by illusionist » April 10th, 2011, 8:56 am

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.
2012-2013 Building Event Captain
Rule 7d. "Event Supervisors are allowed to break any competitors' devices" -bearasauras

User avatar
lllazar
Member
Member
Posts: 839
Joined: November 19th, 2009, 7:20 pm
Division: C
State: IL
Location: Probably at my laptop, multitasking while on AJAX chat....

Re: Rotors

Post by lllazar » April 10th, 2011, 10:13 am

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.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

User avatar
kjhsscioly
Exalted Member
Exalted Member
Posts: 517
Joined: January 16th, 2009, 11:55 am
Division: Grad
State: IL
Location: Chicago

Re: Rotors

Post by kjhsscioly » April 10th, 2011, 10:21 am

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
Member
Member
Posts: 110
Joined: March 18th, 2011, 12:18 pm
Division: B
State: NJ
Location: TGMS FTW

Re: Rotors

Post by thewinner » April 10th, 2011, 6:55 pm

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

Locked

Return to “Helicopters C”

Who is online

Users browsing this forum: No registered users and 1 guest