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i was reading the rule guidelines and it said that blade or wings have to spin on a central axis... how do u get it to do that?

desmond the moonbear wrote:i was reading the rule guidelines and it said that blade or wings have to spin on a central axis... how do u get it to do that?

Ouch, that color hurt.

To the point, see the helicopter duration wiki on this site.

JimY wrote:<SNIP>"mounted or suspended from the bottom of the device such that". This clearly does not allow hollow tube designs for holding the egg, since they have no bottoms. <SNIP>

Sorry if I'm poking at a sore, or this is your view and I'm preaching to the choir, but... Why doesn't the hollow tube have a bottom? What else would you call the lowest part of the device, ie the lower rim? Straight from an on-line dictionary bot·tom/ˈbätəm/ Noun: The lowest point or part

Jeff Anderson
Livonia, MI

Can someone tell me where I could buy a blade? I'm thinking of making my own based on the bought blade, or using the bought blade if the copy fails.

If you just want a helicopter blade, you should be able to go to any brick and mortar or on-line hobby shop and buy/order replacement blades for RC copters.

Careful though, the rules do not allow a commercial rotor assembly. Perhaps more important, I doubt a blad optimised for relatively high speed of an RC copter will be appropriate for this event or anywhere near light enough.

Instead, if you are just trying to figure out where to start, check out the helicopter duration WIKI on this site. You'll learn how to make rotors there and can easily adapt to this event.

Jeff Anderson
Livonia, MI

jander14indoor wrote:

e_sully wrote:Be very careful with laminated rotors that they are not arched, or at least have a solid bottom. A curved rotor will act like a parachute and can get you DQ'd.

That's the second time I've heard that, but I still don't understand it. Nothing in the rules about a curved bottom.

MANY airfoil shapes have curved bottoms but certainly don't act as a parachute. The key would seem to be rotary movement, NOT shape. A flat plat that doesn't rotate acts the same as a parachute.

Where is this statement coming from?

Jeff Anderson
Livonia, MI

Our Coaches were told at the Ohio Coaches Clinic that blades with curved bottoms would be considered a construction violation. They said that even though the blades are turning, they are a combo parachute/blade. We disagree, we have used these blade shapes for years in Wright Stuff, Balloon Launched Gliders, and Helicopters. I never heard an issue of wing/blade shape in those events where shape helps efficiency.

We would love clarification on this topic.

John999 wrote:

jander14indoor wrote:

e_sully wrote:Be very careful with laminated rotors that they are not arched, or at least have a solid bottom. A curved rotor will act like a parachute and can get you DQ'd.

That's the second time I've heard that, but I still don't understand it. Nothing in the rules about a curved bottom.

MANY airfoil shapes have curved bottoms but certainly don't act as a parachute. The key would seem to be rotary movement, NOT shape. A flat plat that doesn't rotate acts the same as a parachute.

Where is this statement coming from?

Jeff Anderson
Livonia, MI

Our Coaches were told at the Ohio Coaches Clinic that blades with curved bottoms would be considered a construction violation. They said that even though the blades are turning, they are a combo parachute/blade. We disagree, we have used these blade shapes for years in Wright Stuff, Balloon Launched Gliders, and Helicopters. I never heard an issue of wing/blade shape in those events where shape helps efficiency.

We would love clarification on this topic.

If you have any doubt, submit a clarification.

John999 wrote:
We would love clarification on this topic.

As wisguy says above, submit a question on the official website. You won't get a clarification here.

Thanks to everyone that gave me tips. I got 4th at the invitational. I used 4 blades and I only got 4th because it weighted 90 grams.(2 rotors)

Sofan--did you say you used 2 or 4 rotors?

Is anyone using two layers of ~6 rotors each?

cconry wrote:Sofan--did you say you used 2 or 4 rotors?

Is anyone using two layers of ~6 rotors each?

Don't take this wrong, but correct terminology is important to clear communications in science and engineering.

I think by rotors, you mean blades. By a layer of rotors(blades) I think you mean a rotor.
Blade, an aerodynamic element that creates lift as it moves through the air.
Rotor, a set of blades rigidly connected that spin around a common axis.

Jeff Anderson
Livonia, MI