Chinook Chat!

Ash123
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Re: Chinook Chat!

Post by Ash123 »

Hey guys
Can someone explain how to build the rotors? I don’t understand how you can create a pitch if they are just two sticks. Also, what is the material used to cover them? Is it wax paper?
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Re: Chinook Chat!

Post by ScottMaurer19 »

Ash123 wrote:Hey guys
Can someone explain how to build the rotors? I don’t understand how you can create a pitch if they are just two sticks. Also, what is the material used to cover them? Is it wax paper?
Mylar is used to cover the rotors and the two main spars are offset vertically and radially then connected with ribs to create the pitch.
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Ash123
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Re: Chinook Chat!

Post by Ash123 »

ScottMaurer19 wrote:
Ash123 wrote:Hey guys
Can someone explain how to build the rotors? I don’t understand how you can create a pitch if they are just two sticks. Also, what is the material used to cover them? Is it wax paper?
Mylar is used to cover the rotors and the two main spars are offset vertically and radially then connected with ribs to create the pitch.
Oh Ok but what do you mean the spars are offset vertically and radially? As in, if they were on an xy plane,they are set apart a certain distance in the y direction And in the x direction?
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Re: Chinook Chat!

Post by bjt4888 »

Ash,

See Jeff Anderson’s post on page 7 of the “Helicopters C” thread in this wiki. He posted several links to standard helicopter plans. One of these plans should answer your question.

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Re: Chinook Chat!

Post by Ash123 »

bjt4888 wrote:Ash,

See Jeff Anderson’s post on page 7 of the “Helicopters C” thread in this wiki. He posted several links to standard helicopter plans. One of these plans should answer your question.

Brian T
Oh ok that definitely helps! One thing I still don’t understand though- How can the rotors be built so you can adjust their pitch? I can see how you could build them to twist around an axis, but how could you force them to lock into a desired pith and not unlock when they are spinning around in air?
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Re: Chinook Chat!

Post by bjt4888 »

Ash,

Once the rotor blade ribs are glued to the leading and trailing edges of the rotors, the pitch is not adjustable. The rotor blade pitch is fixed at the time of construction. I have seen some helicopters constructed using a single center spar on each blade (different than the typical X-spar design) and these could be made to be adjustable in pitch if the single center spar plugged into a tube at the hub. This "center spar" rotor design makes the rotor set look like a typical indoor model airplane propeller (there is a picture of this type in one of Jeff Anderson's links). Be aware that the "center spar" rotor design, if coaxial, usually requires some additional lateral surface area for stability.

I would advise you, as a starting point, to build the "River City Rocket" style rotor, of course to the correct size for this year's rules, (see Jeff's attachments) either for coax or chinook. We experiment with various rotor pitches by building multiple sets of rotors.

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Re: Chinook Chat!

Post by Riptide »

Riptide wrote:Does anyone have any advice for transporting chinooks? We've had some troubles transporting our helicopters to competitions and I'm trying to figure out the best way to safely bring the helicopters on a plane.
Can confirm that cardboard chip boxes and tape are the best solution through extensive testing.
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Re: Chinook Chat!

Post by wx4caster »

We are having issues getting anything over about 50 Secs. (raw time) with our FF Chinook. We have been having some issues with weight, which we know is one of our issues, as we had to add some reinforcement to the sides to keep them from bending/breaking. Even with the carbon fiber. I was wondering what rubber band width was yielding the best results? We are using 0.109 cm rubber, but wonder if going with a thinner or thicker rubber would work better. We do not really wanna go thicker, as we are afraid that will break/bend the wide motors again. We have 10 days before state, and need to get over 65 sec to be in the conversation to win state. We took 2nd at regional, and we were beaten by a FF Chinook that stayed up 65 secs (raw time). Please help.
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