Duration

chalker7
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Re: Duration

Post by chalker7 » May 4th, 2011, 5:52 pm

mrsteven wrote:definitely use curved ribs, airfoils are extremely more efficent. if you soak the balsa in hot water for a few minutes than stroke the balsa across a light bulb (60 watt etc) until its at desired curve. Let it dry, I know that works but if you have the money and the time I'd order them from someone with a lazer cutter
I know someone has been over this before elsewhere, but slicing curved ribs from a template is much much much easier and more accurate than curving it by soaking/drying.
Here's what you do. Get a sheet of metal that is thin enough to cut with scissors but still thick enough to retain strength. Home Depot and other hardware stores sell sheet metal like this for relatively little. Aluminum cans would work but they are usually not tall enough (perhaps one of those tall energy drinks or an arizona iced tea can would be fine). Cut a sheet of the metal out such that the one direction (probably your long one) is the same length as the longest rib you need to cut and the other is a couple inches long, just enough for you to be able to hold it down firmly on your board. Draw whatever shape rib you want along one side. Straight circular arcs are fine, but if you want to get fancy and have a taller leading edge on one side that's fine too, experiment, see what works best. Cut this shape out with scissors. You now have a template.
Cut a sheet of wood (probably 1/16", maybe 1/32") as long as your longest rib (the same size as your template). Make sure the grain is running the same direction as your ribs will be. Lay the template on top of the sheet and make a slice in the wood using the template as a guide with a sharp razor blade. Slide the template down 1/16" and repeat. You now have a curved rib. Repeat along the entire length of the sheet and you will get a number of ribs.
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new horizon
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Re: Duration

Post by new horizon » May 11th, 2011, 7:06 pm

For bending balsa, bending the wood along a form and completely drying it out so there's little to no springback and then slicing it with a balsa stripper will make a really good rib that's pretty strong. I'm pretty sure it's to do with the grain of the grain is going with the rib. The only drawback I see is maybe each batch of ribs you make may be a bit inconsistent and it's pretty time consuming.

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Re: Duration

Post by kmax12 » May 23rd, 2011, 12:06 pm

what were the medaling times at nationals?
09-10
Dynamic Planet - 1st @ regional, 6th @ state, 5th @ nats
Forensics- 2nd @ regional, 1th @ state, 1st @ nats

10-11
Dynamic Planet - 1st @ regional, 4th @ state, 3rd @ nats
Forensics- 2nd @ regional, 1th @ state, 2nd @ nats
Heli 1st @ regional, 1st @ state, 16th @ nats

NTSO4L

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srsvball95
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Re: Duration

Post by srsvball95 » May 23rd, 2011, 12:11 pm

kmax12 wrote:what were the medaling times at nationals?
Our team got 6th with a 2:37
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Re: Duration

Post by chalker7 » May 23rd, 2011, 12:14 pm

kmax12 wrote:what were the medaling times at nationals?
First place was 2:54.
I don't have the spreadsheet in front of me, but off the top of my head 1:45 would have been in the 20th place range and the top ~40 teams broke a mInute.
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Re: Duration

Post by new horizon » May 23rd, 2011, 1:54 pm

Was anyone successful in building a tandem rotor design or were all the helicopters coaxial? Also were there any kit designs that placed in the top 6 at nationals?

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Re: Duration

Post by chalker7 » May 23rd, 2011, 2:54 pm

new horizon wrote:Was anyone successful in building a tandem rotor design or were all the helicopters coaxial? Also were there any kit designs that placed in the top 6 at nationals?
I saw no tandems, everyone was coaxial. Also, everyone had dual rotor designs (as compared to a single, wright bat style or tri-rotor design).
Kits dominated overall, I cannot remember if the first place team had one or not, but several in the top 6 were kits. Well over half of the teams utilized kits in general.
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Re: Duration

Post by mrsteven » May 23rd, 2011, 6:43 pm

I watched all the helicopters and took notes on each. Top all essentially used the Zigler kit or a modification of it. A few teams used a parlor copter with the rotors close to each other and long stick at bottom for stability. but overall of the flights I have to say almost all were the basic parlor helicopter
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Re: Duration

Post by bugsrcool » May 24th, 2011, 6:52 am

The first place team did not use any kit. They designed it from a helicopter they saw online. It took them quite a while to balance the props and that seemed to make it so much more stable so when it came down, it took almost a minute. The copters built before this one were unbalanced and always came down in a zig-zag pattern or slanted.
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mrsteven
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Re: Duration

Post by mrsteven » May 24th, 2011, 1:32 pm

mhm interesting. well I guess I mistakened it- still a basic parlor helicopter though, yes?

I may of mixed up some notes xD
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