Helicopter B/C [Trial]

[Jim_R]

Discussion for Helicopter (division depends on state). Helicopter is featured in many states and divisions this year as a trial event.

Rules:
2010 B/C Rules for New York (also note that NYSSO considers Helicopter B/C to be a pilot event, not a trial event.)
Please PM gh or any other mod/admin with your state's trial rules for Helicopter B/C.

[lightning922]

any ideas?

[jander14indoor]

Three basic concepts I've seen so far.

Dual counter rotating props, one free, one fixed to the vertical motor stick. Newton takes care of making sure both spin in opposite directions. This is the traditional approach among the indoor endurance crowd. See http://www.aviastar.org/helicopters_eng/penaud.php for the earliest example of this. Crude, but it works. Make the rotors bigger for more duration, and move the fixed lower from the bottom of the motor stick to about 2/3 of the way up for increased stability.

Penni copter design, looks like a conventional single rotor, tail rotor concept. See: http://www.freewebs.com/doughtyhobbies/penni.htm

And the Wright Bat, see: http://www.centennialofflight.gov/wbh/w ... Bstory.htm

Longest endurance I've seen is from the dual rotor designs, but who knows. I'm not aware of any three rotor designs, it was thrown in to allow room to innovate.

Jeff Anderson
Livonia, MI

[blue cobra]

Would something like the Penny Copter be feasible for this competition?

[jander14indoor]

As long as you modified it to meet the specs it should be OK. Probably take a lot of modification to the rotor to make it competitive. Also be sure you make the rotor, if the Penni Copter kit comes with rotor pre-built you'll need to replace it.

Oh, and that also depends on which version of the rules your competition uses. The NY state version of the rules from last year have paragraph 2.f TRANSMISSIONS which specifically outlaws pulleys like those in the Penni Copter. The most recent set on the national website have dropped that paragraph. Note, while the two used to match, the national website was recently updated with the modifications we learned from last year. The Helicopter event as run at Nationals, and in Michigan will be done to the rules now posted on the national website.

Differences to point out, lower minimum weight on the new national rules, and larger rotors. Also dropping that paragraph on transmissions.

Jeff Anderson
Livonia, MI

[smartkid222]

i'm planning on making something like the Penaud one you posted but i'm a but confused about which is the right handed propellor and which is the left.
In the picture the free rotating prop is at the top. I belive that this would be the right handed prop? the fixed one, The one at the bottom which you suggested to move closer to the top to obtain greater stablitiy would be the left handed? Does it even make a difference?

also lets say you made it upside down to the picture: having the free rotaing prop at the bottom and the fixed at the top. is there any benefit to this? would this make you switch the type of prop (right/left) in relation to if it's fixed or free?

[jander14indoor]

Doesn't matter which way you make the rotorss turn, so long as you wind in the correct direction. And wrong is pretty obvious as the copter drives straight into the ground instead of climbing!

For 'normal' winding (clockwise) you want a rotor turning like a 'normal' prop like found on Wright Stuff planes for your free rotor on top. And of course the 'fixed rotor (attached to motor stick) is set up the opposite.

But a 'backwards' rotor on top and 'normal' fixed prop below just means you need to wind counterclockwise.

Now, this all switches if you put the free rotor on the bottom. A 'normal' pitched free rotor on the bottom and fixed on top means you need to wind countercockwise.

If you get confused, pick a direction to wind, attach motor and let the free blade spin. You should feel air moving DOWN. Up is bad, wind the other way.

Probably clear as mud, let me know and I'll try to explain another way if needed.

Jeff Anderson
Livonia, MI

[smartkid222]

Doesn't matter which way you make the rotorss turn, so long as you wind in the correct direction. And wrong is pretty obvious as the copter drives straight into the ground instead of climbing!

For 'normal' winding (clockwise) you want a rotor turning like a 'normal' prop like found on Wright Stuff planes for your free rotor on top. And of course the 'fixed rotor (attached to motor stick) is set up the opposite.

But a 'backwards' rotor on top and 'normal' fixed prop below just means you need to wind counterclockwise.

Now, this all switches if you put the free rotor on the bottom. A 'normal' pitched free rotor on the bottom and fixed on top means you need to wind butterfly.

If you get confused, pick a direction to wind, attach motor and let the free blade spin. You should feel air moving DOWN. Up is bad, wind the other way.

Probably clear as mud, let me know and I'll try to explain another way if needed.

Jeff Anderson
Livonia, MI

to make it simpler, for the folowing examples the motor is always wound normaly (clockwise).


are these right?

Heli #1-
Top Prop- free - right handed (you describe as a 'normal WS prop') -
I
I
bottom prop- fixed - left handed-
I


heli #2
Top prop- fixed - right handed (??)
I
I
Bottom pop- free- left handed (??)
I

[smartkid222]

maybe heli #2 is right if you wind counterclockwise??

and it's ok my question was hard to understand and it's a hard concept to explain so thank you.

[jander14indoor]

No, I think you had it right the first time. If the top prop is right handed, and the bottom is left, you wind clockwise, WHICHEVER is 'free'.

And vice versa, top prop left handed, bottom right, you wind counter-clockwise, again, whichever is 'free'.

And I hate missing stupid typos when rereading notes AFTER its too late to edit. Where the heck did

<SNIP>...you need to wind butterfly.<SNIP>

BUTTERFLY come from? What the heck was I thinking about??? I mean its so obvious you need to wind moth... err... dragonfly... err...

Jeff Anderson
Livonia, MI