BuddChiari

Hi guys. This is my first post to this forum, but I have been lurking for several days now.

I've been building and flying .40 and .60 size planes, but I'm ready to delve into the 1/2A size--I think this is the best size for reasons you already know.

Anyway guys, I've been doing some brainstorming on my first 1/2A model. I'd love to scratch build one and I'm constantly trying to think up ways to save weight. I've already learned a ton from reading your posts!

I have been flying this little electric gizmo with Cirrus cs-10 servos--which rock! Of course things can always be smaller. Well, my dad mentioned to me this special wire that they are using in the robot industry for movement, and I immediately thought of a great use for it--deflecting control surfaces! A pull-pull is a nice lightweight setup, but what if you could eliminate the servo?!! Check this out!!! Wire that contracts proportionally with current!

h*tp://www.smallparts.com/products/descriptions/NaW.cfm

Surely I'm not the first to think of this. Anybody have any experience using this stuff? I wonder if this would be feasible for this use-or if the current necessary is prohibitive.

Exciting nonetheless!!!

Duane-RCU

My Feedback: (5)

I don't know, it says slow to moderate speed, and 400mA seems like a lot of juice, but I'm no expert.

flyinrog

My Feedback: (1)

I read about something like this about a year ago, but the wire only (in that article) only expands about 1/8-1/4 of an inch, not enough for much deflection,it was however used in a micro electric plane, dont know that there would be enough power for glow planes either...Rog

Oh, Hi and welcome aboard.....

Lynn S

good idea! borrowed from nature.

matchlessaero

Go over to the Ezone and check out the micro and indoor electric forum.... There are a couple of people experimenting with 'muscle wire' actuation of some ultra sub-micro planes over there.

So far, from what I have read in their threads, the biggest problems have been around response time and movement distance-- IE, muscle wire is pretty slow and they don't contract much......

Still pretty neat nonetheless....[8D]

Andrew

I don't think servos are yet an endangered species. We have used "muscle wire" in our robotics lab and one of the instructors built a small 6 legged walker using muscle wire alone. Our usage revealed 5 potential problems with using it for surface control.

It is not truly linear WRT to current -- wire response is heavily dependent on wire heat -- if the wire has contracted half its operational length when loaded with 100 ma, it may not require an additional 100 ma to reach its contractual limit.

The length the wire will contract is finite and to get extended movement, you need a longer wire. This can be somewhat compensated for by using it in a leverage application.

The wire cools more slowly than it heats -- it either must be terminated with a spring or used in a pull/pull installation -- but it contracts faster than it expands because current application is immediate and cooling is a function of ambient temperature.

To get much power, you must either use a larger wire (requiring more current) or gang smaller wires, like having multiple muscle fibers.

It gets HOT -- if you used an extended length, say in a pull/pull, it would be necessary to keep it away from the fuselage and you would need to have wiring attached at each end.

Muscle wire usage will expand with experimentation and improvements in the technology of its application, but I don't foresee Futaba, Hitec or JR closing shop in the near future. However, like any emerging technology, individual innovation will find ways to make it useful.

the "other" Andrew

kew

actually all size airlanes fun to fly..the bigger ones fly better but i prefer the small ones ..and what i mean by fly better the bigger ones are less disturbed by the wind!...