Helicopter B/C [Trial]

Taran
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Re: Helicopter B/C [Trial]

Postby Taran » April 24th, 2010, 10:03 am

Is it possible to bend the balsa sheets to make a propeller? Otherwise it seems hard to make an efficient propeller.

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baker
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Re: Helicopter B/C [Trial]

Postby baker » April 24th, 2010, 10:21 am

Taran wrote:Is it possible to bend the balsa sheets to make a propeller? Otherwise it seems hard to make an efficient propeller.

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Yes, cut out slightly larger the piece of balsa with the design of the prop. Soak in hot water for about an hour, place on form and hold with rubber bands. Let dry over night, cut out prop with razor blade or skizzors, can't spell scissors.. :D

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Re: Helicopter B/C [Trial]

Postby OlympiadLover » April 24th, 2010, 4:51 pm

How long should these last?
10' State: 1st: It's About Time and Experimental Design,, 2nd: Picture This, State, National team/UIUC
11' State: 1st: Experimental Design and 1st Wind Power, 3rd Mousetrap Vehicle, National team/UW-Madison
12' State: 3rd Thermodynamics, 3rd Water Quality, 8th Experimental Design, National team/UCF

baker
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Re: Helicopter B/C [Trial]

Postby baker » April 25th, 2010, 6:35 am

They'll hold up quite well, as good as any prop made of other materials. But, could be a little heavier than you might want. How long will they last? Until you hit the ceiling, the speakers, rafters, basket ball hoops, the wall, the uncontrolled dive into the floor...other than that, I'd say 15 seconds. We built ours with 1/32 material, props weight was just slightly less than 1 gram. We built a large, medium and small one. We let the stop watch tell us which was best.

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Re: Helicopter B/C [Trial]

Postby SOCoach » April 25th, 2010, 4:05 pm

Couple of questions for those in the know . . .

On the double prop design, the fixed rotor I am assuming by "fixed" it means it does not move right? It only spins as the motor stick spins . . is that correct?

Secondly, does anyone know how to make balsa props (the look like the ones used on penny planes)

cypressfalls Robert
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Re: Helicopter B/C [Trial]

Postby cypressfalls Robert » April 25th, 2010, 4:13 pm

SOCoach wrote:Couple of questions for those in the know . . .

On the double prop design, the fixed rotor I am assuming by "fixed" it means it does not move right? It only spins as the motor stick spins . . is that correct?

yes that is correct

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Re: Helicopter B/C [Trial]

Postby baker » April 25th, 2010, 4:27 pm

This one show an outline of a home made propeller
http://www.indoorfreeflight.com/novice/dadnov.gif

Taran
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Re: Helicopter B/C [Trial]

Postby Taran » April 25th, 2010, 5:44 pm

Umm, I only see a Wright Stuff Design, or is it the thing at the bottom right?

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Re: Helicopter B/C [Trial]

Postby jander14indoor » April 25th, 2010, 7:57 pm

Making lightweight indoor props from wood. OK, this is WAY more hardcore than you need in that the weight of this prop is 0.170 grams and your target is more like 0.8 to 1.0 gm per rotor. BUT, the processes and procedures can all be used to get an appropriately strong and heavy prop for SO Helicopter. See:
www.indoorduration.com/INAVHobbyShopper4.htm
www.indoorduration.com/INAVHobbyShopper5.htm

Use thicker wood, make it larger (40 cm or 16 inches vs 12 inches in that article), use denser wood, etc.

But, key point, PROCEDURE is correct in that it will result in fairly high efficiency, good working props or rotors.

Probably some other articles out there, look under EZB props or Penny Plane props.

Jeff Anderson
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Re: Helicopter B/C [Trial]

Postby chlorine kills » April 29th, 2010, 6:25 pm

FAIL my helicopter I built in 3 days won 5th at state

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1st in optics at TX state.

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Re: Helicopter B/C [Trial]

Postby Gujju Builder » April 30th, 2010, 2:12 pm

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

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Re: Helicopter B/C [Trial]

Postby Gujju Builder » April 30th, 2010, 2:15 pm

Btw we need some fancy pancy rubber banditos.

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Re: Helicopter B/C [Trial]

Postby Gujju Builder » April 30th, 2010, 2:17 pm

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

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Re: Helicopter B/C [Trial]

Postby jander14indoor » April 30th, 2010, 3:27 pm

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

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Re: Helicopter B/C [Trial]

Postby Gujju Builder » May 7th, 2010, 6:25 pm

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


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