Rotors

[mrsteven]

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?

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?

i believe it was a elliptical. the thought is that theyre better if made correctly, but very hard to make correctly. I would stick with a heliptical design. The 'flat' blade design i havent seen but some say it works- but I personally wont spend any time working on it.

Until proven otherwise, I think its trolling. However, Ill be having a few of my friends recording times at COD's regionals so I guess Ill see for sure then if thsom's claims are backed up

[thsom]

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?

Yes it does look like that one you linked to and I understand what you mean by helical, they are not helical in that picture and nor are they in mine. When I said curved I meant with air foils so literally curved rotors but still that design in the link (just with foils in the rotors).

Edit: Mrsteven, what school are you from?

[mrsteven]

I'm from BG (it even says it in my location on the left <--- )

My regional is CLC but I've got friends on teams at your regional
Hope to hear about that time- its quite an interesting time, + seeing stevenson/new trier at my regional. Should be a fun day!

edit: the 'flat' blades with an 'air foil' is essentially heliptical from how I'm visualizing this....

[Bob8372]

Would having rotors at the top of the copter cause a higher or lower center of gravity?

[thedoctor]

Would having rotors at the top of the copter cause a higher or lower center of gravity?

Well...most people have two rotors--one on top and one on bottom so that you have more lift. By the way I see you're from NC; what regionals are you in?

[mrsteven]

Would having rotors at the top of the copter cause a higher or lower center of gravity?

depends where your weight is. 2 blades is gooooood generally lol

You want to have your center of gravity towards the bottom, so after you finish your helicopter (should be UNDER the weight restrictions or just on it) add a bit of balast (clay, plastic etc) to the bottom of the motor stick to aid in the helicopter staying upright in its decent downwards

[jander14indoor]

I actually believe two minutes plus is possible with a non-helical rotor. Yes helical is better (note, curved ribs to NOT make a rotor elliptical as someone else commented). Better still is helical with elliptical blade shape. Question becomes how MUCH better. The non-helical rotors aren't 10% as effective as helical ones. More like 80%. Since I expect 3-4 minutes or better at nationals by the top teams, 2:49 is good, probably will win many regionals, some states, and wouldn't be entirely embarrassed at nationals.. Its not a world beater. but it can fly well.

Jeff Anderson
Livonia, MI

[mrsteven]

I don't think we're debating the concept of that time as much as its possibility with the design thsom followed on the NC SO page, which is extremely basic.

The time itself is possible but I'm a doubter with the design and only that design as an aid

[jander14indoor]

No, I'm saying the simple NC design will do better than you think and I believe a properly tuned (right pitch and rubber match) simple one is capable of 2 minutes plus. Not that 2 minutes plus is reasonable for a sophisticated helicopter design.

Jeff Anderson
Livonia, MI

[kitesh]

Forgive me if this has been asked, but I didn't see such a clarification listed.


I am in a division where rotors are defined as "surfaces that contribute lift by rotating on a common path around a vertical axis. The helicopter may use up to three fixed pitch rotors, not exceeding a maximum diameter of 35.0 cm."

Does 'Fixed Pitch' mean:

1. Pitch does not change during flight
2. The pitch (Angle of the chord) is constant across the radius of the rotor

# 2. would seem to outlaw many of the interesting designs, like helical or elliptical (optimized) rotors.