Rotors

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illusionist
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Re: Rotors

Post by illusionist » February 11th, 2012, 7:08 pm

A problem that I've been recently noticing is that when we attach the rubberband to our free rotor's hook (rotor shaft), the force causes the top spar of the rotor (the one closest to the body) to collapse so that the two spars are touching each other directly (we're left with two flat triangles basically). It's definitely a glue problem, but I've never noticed it before? Any ideas on what caused it, or tips to prevent it?
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Re: Rotors

Post by blue cobra » February 11th, 2012, 7:36 pm

thsom wrote:Ok, well I have built both and gotten a significantly better time with the non-helical one (not eliptical either, the one I linked to at sciencenc.com). I am not sure why, but it may be due to the lack of skill I have and no jig for building those rotors. I'll stick with the other one, (with my modifications I was able to get a 2:27).
I'd definitely be interested to hear how you got 2:27 out of such an elementary design.
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Re: Rotors

Post by chalker7 » February 11th, 2012, 7:44 pm

illusionist wrote:A problem that I've been recently noticing is that when we attach the rubberband to our free rotor's hook (rotor shaft), the force causes the top spar of the rotor (the one closest to the body) to collapse so that the two spars are touching each other directly (we're left with two flat triangles basically). It's definitely a glue problem, but I've never noticed it before? Any ideas on what caused it, or tips to prevent it?
The only thing I can suggest (without some pictures of the physical helicopter) is to add more bracing ribs or somehow otherwise increase the strength of your rotors.
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Re: Rotors

Post by mrsteven » February 11th, 2012, 9:23 pm

^ I would as well Blue Cobra.
Especially considering I've seen very very few of helicopters by that particular design that actually get off the ground for more than 10 seconds let alone an impressive 2:27.

For illusionist: if your talking about the small bit of wood between the 2 rotors spars collapsing (that holds them apart) then try more dense wood. Glue probably isnt the issue. At some point there is just too much stress and you need to bump it up if thats happening. Althought ill repeat Chalker.. without a photo I cant really tell what you mean... im a visual person myself
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Re: Rotors

Post by thedoctor » February 11th, 2012, 9:28 pm

thsom wrote:Ok, well I have built both and gotten a significantly better time with the non-helical one (not eliptical either, the one I linked to at sciencenc.com). I am not sure why, but it may be due to the lack of skill I have and no jig for building those rotors. I'll stick with the other one, (with my modifications I was able to get a 2:27).
Perhaps this is a miscommunication? Like others, I can't believe that a non-helical design would get a time as good as 2:27--it just seems to defy physics; otherwise, I think national times would be incredibly high compared to what they are now. I mean no disrespect but maybe 2:27 is supposed to be 2.27 seconds or something like that?

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Re: Rotors

Post by lucwilder42 » February 11th, 2012, 10:33 pm

thedoctor wrote:
thsom wrote:Ok, well I have built both and gotten a significantly better time with the non-helical one (not eliptical either, the one I linked to at sciencenc.com). I am not sure why, but it may be due to the lack of skill I have and no jig for building those rotors. I'll stick with the other one, (with my modifications I was able to get a 2:27).
Perhaps this is a miscommunication? Like others, I can't believe that a non-helical design would get a time as good as 2:27--it just seems to defy physics; otherwise, I think national times would be incredibly high compared to what they are now. I mean no disrespect but maybe 2:27 is supposed to be 2.27 seconds or something like that?
Nats copters were non-elliptical but helical.
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Re: Rotors

Post by thsom » February 12th, 2012, 7:21 am

Oh no, it is 2:27. I just tested another one however (still with non-helical rotors) but it had cured rotors and it got a time of 2:49.

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Re: Rotors

Post by illusionist » February 12th, 2012, 7:38 am

thsom wrote:Oh no, it is 2:27. I just tested another one however (still with non-helical rotors) but it had cured rotors and it got a time of 2:49.
You sure you aren't trolling? :shock:
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Re: Rotors

Post by thedoctor » February 12th, 2012, 9:46 am

illusionist wrote:
thsom wrote:Oh no, it is 2:27. I just tested another one however (still with non-helical rotors) but it had cured rotors and it got a time of 2:49.
You sure you aren't trolling? :shock:
There has to be some sort of miscommunication between thsom and everyone else...didn't Mr. Anderson build a non-helical helicopter last year but still get a much better time with a helical one?

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Re: Rotors

Post by illusionist » February 12th, 2012, 2:22 pm

thsom, do you understand what helical means? Does your helicopter look something like this: http://gallery.scioly.org/details.php?image_id=3315 ?

And you also said your new one has "cured" rotors. Did you mean "curved" so that they're shaped like an egg, or "curved" as in twisted?
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