Helicopter B/C [Trial]

[Gujju Builder]

Hey guys, do ya'll know where to get helicopter kits. That fly!!!! thanks i love yall were from texas. Please help we are desperate. thanks.were goin to nats and were from texas. Thanks guys!!!

[Gujju Builder]

Btw we need some fancy pancy rubber banditos.

[Gujju Builder]

Btw we need some fancy pancy rubber banditos for the helicopterito.thanks from teeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeexxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxaaaaaaaaaaaaas

[jander14indoor]

Don't think rubber bands. You need Tan Super Sport from www.faimodelsupply.com. It comes in long continuous strips, you cut off the length you need to be 2.0 gm and tie the ends in a knot to make a loop.

SOME hobby shops carry Tan Super Sport too, some other online sources, but FAI Model Supply is the original source. I'd suggest you start with a qtr pound of 3/32 wide.

For kits, unfortunately no currently available kits meet the rules. The existing Wright Bat kits have the propellor already made, you have to make your own for the event. The other common kit is the Penni Copter, I think its rotor is also pre-made.

Better to look back up this chain for hints and tips on designs and build from scratch. There's a Wright Bat design on the Illinois site, but to be legal for nationals you need to change the rotor from the plastic cut out pieces to balsa. There's some nice twin rotor designs that are WAY to hard core for these rules (less than 1 gm copters) but the design approach will work. There's also a video of a good design concept on youtube pointed at a way back up the chain. Flights are kind of short, but the basic design is capable of more.

Its probably better to build from scratch than to wait on a kit to arrive that you have to modify the heck out of.

Jeff Anderson
Livonia, MI

[Gujju Builder]

can we use a parachute on our helicopter to make it fall slower

[Gujju Builder]

What parts do u need to build a regular helicopter. We dont know what to buy?????!?!?!?!?!?!? Are there any plans.

[lllazar]

What parts do u need to build a regular helicopter. We dont know what to buy?????!?!?!?!?!?!? Are there any plans.

Is this for nats?

ON topic, read this thread, there are a lot of basic design ideas floating around, seeing as i think your new to this.

[red_moon]

Right now, I'm working on our rotors, and I read Jander's post about the helical blades, and the way I understood it, if the rotor is larger, the angle of the end is still 17.6 degrees, based on that cylinder visual. I doubt this is right, and was wondering if someone could clarify (I've spent hours researching).

This brings me to another question: for a helical rotor, the middle is straight up and down (or very nearly?), but do the ends ever exceed 90 degrees from the middle? If, say, the presumed angle of the end is 17.6 degrees, would the total twist of the rotor be something like 144.8 degrees (or 72.4 on each side)?

[jander14indoor]

Dang a hard one. If you look back a ways on this thread I think you'll find pointers to propellor theory in case I get lost with this explanation.

Yep, here's one: http://www.gregorie.org/freeflight/shee ... index.html

Spend some time understanding that if you haven't already.

Answering some of your specific questions. I'm not sure where you got 17.6 degrees for the tip, this is only correct for one pitch/diameter ratio, not in general. Yes, near the hub the blade ideal angle approaches being parallel to the rotor axis (straight up and down). No the tips never quite reach 90 degrees from the middle. They get closer as the blade gets longer, but never reach it.

I'm going to stop with that for now because the existing explanations are better than what I can write. If that didn't cover what is confusing you, holler and I'll look up a reference to copy with some diagrams.

Jeff Anderson
Livonia, MI

[red_moon]

God, I'm stupid. I took one look at the picture and finally realized what you meant...haha, I guess I'm just a visual person.

Thanks!