Helicopter Testing

Locked
User avatar
mrsteven
Exalted Member
Exalted Member
Posts: 815
Joined: March 13th, 2011, 5:40 pm
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by mrsteven »

thedoctor wrote:
thsom wrote:but aren't you afraid that the disc may fall of or break if it is so thin?
Balsa wood, although thin and light, is surprisingly strong and if glued correctly won't fall off. Just think about your rotors; they can spin repeatedly into walls and will still stay intact.
with that said, i also had some liquid steel (epoxy), with that I promise you the helicopter could be blown up and the joint between the rotor and disk will be intact :D
Although that was total over kill i added at the last moment- I would recommend a few coats of CA glue (tried just one at the joint, came off) Don't go CRAZY with it, but use in exess. You don't want a wonderfully long flight to be ruined by the disk falling
2011 Helicopters State Runner-up
2012 Helicopters State Champion
2013 Robot Arm State Champion
jarrred_1415
Member
Member
Posts: 34
Joined: December 13th, 2010, 1:28 pm
Division: Grad
State: OH
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by jarrred_1415 »

thsom wrote:Quick question guys, i'm new at this any my copter keeps turning on its side and moving then like a wright stuff airplane (obviously not in circles though). What causes this? Is it that the copter is top heavy or what?
Can be a multiply things 1. the props aren't balanced. in which case you need to set your helicopter up on a stand so that the motor stick is horizontal and the props can spin freely. and slowy spin them and balance them so that they end up balancing out perfectly horizontal. 2. your motor stick is weak, which is just getting a new one and transfering stuff 3. the props/thrust bearing aren't built straight which the only solution is rebuilding better.
User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 1 time

Re: Helicopter Testing

Post by illusionist »

thsom wrote:Quick question guys, i'm new at this any my copter keeps turning on its side and moving then like a wright stuff airplane (obviously not in circles though). What causes this? Is it that the copter is top heavy or what?
Actually, there is a much easier solution than the ones stated above (although those are all things you should check for anyway). Your helicopter is top-heavy. In order to fly vertically, most of the mass has to be concentrated towards the bottom. So simply adding clay should correct this problem. This is why most people would suggest that you build your helicopter under 3.5g, so that you can bring it up to the requirement by adding clay or other material to the bottom end of your helicopter.
Orange714
Member
Member
Posts: 61
Joined: December 19th, 2011, 3:43 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by Orange714 »

I'm kind of new, and if you added modeling clay would you just stuck it on the bottom of the rotor? Like so the clay would spin along with the rotor? Also when we've tested our helicopter shoots up perfect straight really fast, stays for maybe 5-15 sec and then kinda swoops down in circles. When it lands it has a lot of winds on it. We wind it like 65-75 times with a 10:1 ratio winder and the rubber band is like 10-11 inches (If we wind it any more the rubber snaps, I don't know why....) How would you increase the time? We've tried double banding the rubber band and that didn't work too well....Do we just get better rubber and wind it even more?
Thanks :D
User avatar
chia
Member
Member
Posts: 558
Joined: January 13th, 2009, 5:09 pm
Division: Grad
State: IL
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by chia »

Orange714 wrote:I'm kind of new, and if you added modeling clay would you just stuck it on the bottom of the rotor? Like so the clay would spin along with the rotor? Also when we've tested our helicopter shoots up perfect straight really fast, stays for maybe 5-15 sec and then kinda swoops down in circles. When it lands it has a lot of winds on it. We wind it like 65-75 times with a 10:1 ratio winder and the rubber band is like 10-11 inches (If we wind it any more the rubber snaps, I don't know why....) How would you increase the time? We've tried double banding the rubber band and that didn't work too well....Do we just get better rubber and wind it even more?
Thanks :D
I would suggest putting it as low on the motor stick as you can, rather than on the rotor itself, since adding weight to the rotor will change the rate at which it turns and how aerodynamic it is, and probably not for the better.
By rubber band, do you mean an actual store-bought circle of rubber, or competition rubber like the stuff you can buy at FAI Model Supply? If it's the former, you may want to consider investing in competition rubber (look through the Rubber thread for links), maybe just a quarter pound to start with. If you already have something like that, are you using a lubricant (silicon-based or Armor-all are what I've heard of)? The rubber can snap pretty easily if you wind it dry, and it might not stay in the air as long.
A couple of posts back there was a discussion on helicopter wobble - maybe that might apply to you. Since your helicopter simply isn't lasting that long in the air, though, it could be a problem with your rotor design (ie pitch?).
(avatar is by xamag)
Favorite events: Anatomy, Microbe Mission, Ornithology, Circuit Lab, Helicopter
NCHS '13
==>
Orange714
Member
Member
Posts: 61
Joined: December 19th, 2011, 3:43 pm
Division: C
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by Orange714 »

I guess it does wobble when it comes down, but when it goes up it shoots up. Yes we're using competition rubber 3/32 inch from freedomflightmodels. We're using lube, but I have no idea if it's silicone based. It came with the rubber we bought. How long should the rubber we're winding be? Our rubber tied together is about the length of our helicopter which is about 13-14 inches.
thsom
Member
Member
Posts: 241
Joined: December 27th, 2011, 10:26 am
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by thsom »

If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.
thsom
Member
Member
Posts: 241
Joined: December 27th, 2011, 10:26 am
Division: C
State: IL
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by thsom »

If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.

EDIT: Sorry for the double post... literally... i don't know how to delete them :oops:
Last edited by thsom on January 16th, 2012, 7:34 pm, edited 2 times in total.
User avatar
illusionist
Member
Member
Posts: 942
Joined: March 20th, 2010, 4:13 pm
Division: C
State: MI
Has thanked: 0
Been thanked: 1 time

Re: Helicopter Testing

Post by illusionist »

thsom wrote:If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.
1/16 might be a little too thick in my opinion.I would stick with 1/32. The biggest factor is weight. With the traditional frame-and-covering design, you only have 1/16 around the edges. Using a 1/16 solid blade would weigh a ton. 1/32 has enough strength for these helicopters and is somewhat light enough.
jarrred_1415
Member
Member
Posts: 34
Joined: December 13th, 2010, 1:28 pm
Division: Grad
State: OH
Has thanked: 0
Been thanked: 0

Re: Helicopter Testing

Post by jarrred_1415 »

Orange714 wrote:I guess it does wobble when it comes down, but when it goes up it shoots up. Yes we're using competition rubber 3/32 inch from freedomflightmodels. We're using lube, but I have no idea if it's silicone based. It came with the rubber we bought. How long should the rubber we're winding be? Our rubber tied together is about the length of our helicopter which is about 13-14 inches.
you need more torque throughout the flight, increase the width of your rubber or make a double loop of the 3/32 you have although i suspect that it might be too much. FAI website sells a .154 width that would probably work very well based off what you're saying
Locked

Return to “Helicopters C”

Who is online

Users browsing this forum: No registered users and 3 guests