Designs and Kits

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chia
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Re: Designs and Kits

Postby chia » Sun Feb 20, 2011 5:37 pm

You know, I was actually thinking about that. Depending on the design of your helicopter, though, it would likely be either unnecessary or impossible.
...Does it matter where on the motor-stick the fixed rotor is? (I'm assuming that's why you would want it adjustable)
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Re: Designs and Kits

Postby lllazar » Sun Feb 20, 2011 10:23 pm

Yes it certainly does matter.
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Re: Designs and Kits

Postby chia » Mon Feb 21, 2011 1:45 am

Well, I know it does matter, but what's the effect of attaching it closer to the free rotor compared to having it at the other end of the motor stick?
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Re: Designs and Kits

Postby lllazar » Mon Feb 21, 2011 1:54 am

Well, from personal experience, my time goes up as i bring the rotor closer and closer to the middle of the rotor stick, but then not quite to the middle, my times start to take a dive for the worse. Take from that what you will, but i think experimentation is the key to figuring out exactly where to place your fixed rotor.
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Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
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Re: Designs and Kits

Postby chia » Mon Feb 21, 2011 2:15 am

Huh. I would have figured putting them as far apart as possible might work best (most designs I've seen do it this way).
I think more of an issue for me is going to be making sure the rotors are spinning on the same axis.
What do people have to say about having both rotors attached to the rubber? I've seen it in pictures and such, but I'm still not entirely certain how it would work. Both rotors would spin as a result of the rubber (in opposite directions), so the rubber is let out faster? Eh, I'm probably just confusing myself.
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Re: Designs and Kits

Postby jetnet22 » Mon Feb 21, 2011 8:03 am

I would have figured putting them as far apart as possible might work best, this looks really good! Image

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Re: Designs and Kits

Postby lllazar » Mon Feb 21, 2011 11:54 pm

For anyone having balance issues, a few tips i've learned from this past weekend:

1. Having both rotors on the same precise vertical axis helps. A lot. By this i mean you should build your copter so that the fixed rotor and free rotor are essentially 1 above the other (not distance wise, i am NOT referring to the ditance between the two rotors, just in terms of relative position).

2. Make sure your rotors are balanced. Now, assuming your building a ribbed mylar rotor (or other type of material, i think japanese tissue paper is also popular?), the wooden frame should be made of wood that is hand picked for the right mass. Use strong stiff sticks for the main long pieces, and use lighter stuff for the ribs. Make sure the mass on both sides is about the same by massing the cut pieces before hand. This helped me a lot going from my 2nd heli which was terribly unbalanced to my 3rd heli, which wobbled nowhere near as much. Continuing on, when putting on the mylar, assuming you make no mess ups and don't have to patch (and a little bit on that later), the finished product should be fairly well balanced.

3. About that patching up business. Don't even go there. Unless it's a very minute error and can be fixed with just a little bit of covering and glue, just start over. Patching up a tear that's more than a few millimeters in size is going to 1. add more weight on one side, making the rotors unbalanced, and 2. if you happen to care about aesthetic value, it just makes for an ugly copter. Either way, with a good jig, it should take less than 45 minutes to make a complete rotor, and hey i do it by myself so i would know,

Hope that helps, balance is a key to making your copter as efficient as possible.
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Re: Designs and Kits

Postby blue cobra » Tue Feb 22, 2011 7:17 pm

It only takes you 45 minutes to build a rotor? The jigs I made significantly cut down time, but with all the sanding necessary to get the ribs to fit right, it still takes me much longer than that.
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Re: Designs and Kits

Postby lllazar » Wed Feb 23, 2011 2:31 am

Sanding? My jig allows me to dip the ribs into some water, and bend it along the jig and glue right in that position. With a little masking tape to hold everything down, and a blow dryer, the rotor comes out with exactly as much curvature as i want. So ya, i don't really end up having to sand anything.

But really what does it matter, it's not like towers where you build a tower or two every week (or in some cases more), the only need to rebuild would be because there has been a major change to your design or something breaks/gets stuck.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
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Re: Designs and Kits

Postby Frogger4907 » Mon Feb 28, 2011 4:03 pm

I kind of wish kits weren't aloud... any one can throw together of kit, that professionals design to stay up for 2 min... :|
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Re: Designs and Kits

Postby jander14indoor » Mon Feb 28, 2011 8:48 pm

What kit are you talking about? I've seen NO reports of a kit hitting two minutes, and many about students struggling to even get off the ground with a kit. So far no evidence that kits give any of advantage that I've seen. If you have evidence, provide it, we can certainly look at that for next year.

Keep in mind, the purpose of these flying events is not so much design (though there's more room in helicopter than Wright Stuff for desing surprises) but test and evaluation. Without test and evaluation, there's still no way I've seen to succeed with this event even if someone hands you a good copter.

Thanks,

Jeff Anderson
Livonia, MI

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Re: Designs and Kits

Postby lllazar » Mon Feb 28, 2011 10:17 pm

Haha this is very true, my rotors as far as i can see are very well constructed and in theory the design should work quite well, but we started at the beginning getting times of 30-40 seconds. Only through testing and changing factors did we get our time up.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

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lllazar
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Re: Designs and Kits

Postby lllazar » Mon Feb 28, 2011 10:20 pm

Haha this is very true, my rotors as far as i can see are very well constructed and in theory the design should work quite well, but we started at the beginning getting times of 30-40 seconds. Only through testing and changing factors did we get our time up.
2011 Season Events~

Fossils (Regionals ~1st) (State ~6th)
Towers (Regionals ~1st) (State ~3rd)
Helicopter (Regionals -3rd gahhh) (State ~5th)
Wind Power (Regionals ~1st) (State ~3rd TIERED!)

Hooray for getting everything i wanted?

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Re: Designs and Kits

Postby Frogger4907 » Tue Mar 01, 2011 7:27 pm

jander14indoor wrote:What kit are you talking about? I've seen NO reports of a kit hitting two minutes, and many about students struggling to even get off the ground with a kit. So far no evidence that kits give any of advantage that I've seen. If you have evidence, provide it, we can certainly look at that for next year.

Keep in mind, the purpose of these flying events is not so much design (though there's more room in helicopter than Wright Stuff for desing surprises) but test and evaluation. Without test and evaluation, there's still no way I've seen to succeed with this event even if someone hands you a good copter.

Thanks,

Jeff Anderson
Livonia, MI

The River city rocket hits around 2 min according to their site, at http://www.turnertoys.com/G1/science_ol ... lanes1.htm as well as the kit below it can hit 2 min. Although I have never seen this, you can see that they say the kits are capable of two min. Maybe there not?
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Re: Designs and Kits

Postby smartkid222 » Tue Mar 01, 2011 8:28 pm

Although websites usually inflate the times to exaggerate the capabilities of the kits, it does seem possible for a helicopter from a kit to reach 2 minutes.
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