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What is meant by helical shaped rotors?

thsom wrote:What is meant by helical shaped rotors?

Instead of two flat blades, the rotors start vertical at the axis and then gradually transition into more of a horizontal orientation. check out the image gallery for many examples

lucwilder42 wrote:

thsom wrote:What is meant by helical shaped rotors?

Instead of two flat blades, the rotors start vertical at the axis and then gradually transition into more of a horizontal orientation. check out the image gallery for many examples

Essentially what you see most people use. They have curved ribs to conform with the shape.
Elliptical is the same idea, but in an egg type shape to reduce drag
edit: usually has a film or paper covering to make the transition from the horizontal to vertical and curved to have a kind of air foil type thing

Is this an example:
http://gallery.scioly.org/details.php?image_id=3291
or this:
http://gallery.scioly.org/details.php?image_id=3327

thsom wrote:Is this an example:
http://gallery.scioly.org/details.php?image_id=3291
or this:
http://gallery.scioly.org/details.php?image_id=3327

first one.
2nd is either elliptical or just flat blades depending on if the egg shape is contorted or not

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).

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 be interested in hearing about this helicopter getting a 2:27 without a jig, thats quite a feat for a novice builder (even for some of us veterans).
Especially from such an elementary design as the NC SO site you posted before had.
Do you use a large cord length or a specifically odd rubber width?

I cut my own rubber. I don't know the measurement off the top of my head it's written down somewhere in one of my files.

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).

are you talking about the one on this page? http://www.sciencenc.com/event-help/helicopters.php you confused me when you said "The one I linked to"

yes that one, sorry for the confusion