Helicopters B

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mrsteven
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Re: Helicopters B

Postby mrsteven » Tue Mar 12, 2013 2:27 am

fifty_missions wrote:On testing a given rubber motor, wind the motor (off the helicopter) to destruction while counting the winds and tracking the torque. The rule of thumb is that the safe maximum winds and torque will be 20% less than that at the point of destruction.

20%? Thats alot. Last 2 years I was running the rubber 1 wind (with a 10:1 ratio) under breaking. 20% leaves a lot of potential winds unused
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Re: Helicopters B

Postby _HenryHscioly_ » Sun Mar 31, 2013 7:06 am

Is using a drill to wind rubber band practical?

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Re: Helicopters B

Postby chalker7 » Sun Mar 31, 2013 6:39 pm

_HenryHscioly_ wrote:Is using a drill to wind rubber band practical?


It's not recommended. A big component of winding is knowing exactly how many winds you have put on the rubber band as well as the "feel" of how much torque/how close the rubber band is to breaking during winding. Using an electric drill obscures both of those pieces of information.
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Re: Helicopters B

Postby retired1 » Tue Apr 02, 2013 3:10 pm

It would only be rational if you were doing the winding on a torque meter. I am old school, I like the 10:1 winder.

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Re: Helicopters B

Postby hogger » Tue Apr 02, 2013 8:58 pm

What is the reason why one uses torque meter in this event? I'm not an expert but when I did wrightstuff, the main reason for torque meter was to be able to have better control of the height that the plane would reach with the torque reading. The torque reading gives you sort of the instantaneous power being applied to the prop of the plane, and it approximately will control the maximum height of wrightstuff plane. In this event, if there is no obstruction before the ceiling, it seems that you want to wind the rubber to the max and does not care too much how high it would get, thus one should not care too much about initial torque? Probably there are more to it than that, I guess that is why I am asking.

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Re: Helicopters B

Postby mrsteven » Tue Apr 02, 2013 9:07 pm

To know the breaking point. Before the rubber band breaks, the torque spikes very noticably. If you use a torque meter, you can see that spike and stop winding before the breaking point.
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Re: Helicopters B

Postby hogger » Tue Apr 02, 2013 9:21 pm

Ahh yes. It is another indication along with the "feel" that the winder must sense before the break and reducing the length or the stretch until you run out of stretched rubber. Also probably a good way to get consistent maximum winding by giving feedback to confirm what you are sensing in the tension and not to prematurely reduce the stretch until the torque gets to certain point. If that makes any sense.

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Re: Helicopters B

Postby chalker7 » Wed Apr 03, 2013 1:53 am

hogger wrote:What is the reason why one uses torque meter in this event? I'm not an expert but when I did wrightstuff, the main reason for torque meter was to be able to have better control of the height that the plane would reach with the torque reading. The torque reading gives you sort of the instantaneous power being applied to the prop of the plane, and it approximately will control the maximum height of wrightstuff plane. In this event, if there is no obstruction before the ceiling, it seems that you want to wind the rubber to the max and does not care too much how high it would get, thus one should not care too much about initial torque? Probably there are more to it than that, I guess that is why I am asking.


Beyond simply using them to predict the breaking point for a motor, there is another use for torque meters. We talked about it quite a bit last year, here's a good post to get you started: viewtopic.php?f=124&t=3063&start=45#p191095
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Re: Helicopters B

Postby Skink » Wed Apr 03, 2013 2:03 am

How do you troubleshoot a significant (20% reduction...ouch) decrease in flight time? Is it a result of rubber bands getting old? Our rubber bands have a few whitish splotches. I assume those are blemishes of some kind. Does that mean replace them? We typically wait until they begin to tear somewhere before discarding them. Thanks.

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Re: Helicopters B

Postby mrsteven » Wed Apr 03, 2013 2:09 am

Skink wrote:How do you troubleshoot a significant (20% reduction...ouch) decrease in flight time? Is it a result of rubber bands getting old? Our rubber bands have a few whitish splotches. I assume those are blemishes of some kind. Does that mean replace them? We typically wait until they begin to tear somewhere before discarding them. Thanks.

Tan sport Rubber for helicopters lose elasticity after a few flights. I wouldnt use them past 4 flights. I noticed last year that the 2nd flight (occasionally third) on each rubber band yielded the best flight time of the bunch. Stretched out enough to be more profitable but not so much it loses the ability to be effective. Switch out motors often
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Re: Helicopters B

Postby Skink » Wed Apr 03, 2013 2:13 am

In other words, a new rubber band should be used weekly assuming we get in about five flights in a week? That gets a bit pricey. In any case, thanks, bro.

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Winding Stooges not allowed?

Postby gmui » Sun Apr 07, 2013 10:42 pm

Hi,
Has anyone been allowed to use a winding stooge during Regional or States? I just got clarification from the NY state coordinator that students will not be allowed to attach anything to the supervisor's table nor bring their own table. Is that how it's been for previous years and/or for other states?

Seems like kind of an odd restriction. Should we just hold the torque meter?

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Re: Helicopters B

Postby jander14indoor » Mon Apr 08, 2013 1:48 am

I can see not being allowed to attach things to the judges table, I never allow it. I'm busy checking helicopters, etc, its just a good way to get your helicopter broken.

Are they providing tables for the competitors to set up on?

Not sure why you can't bring your own table unless not enough space where they are flying. Racquet ball, handball, squash courts have become very popular as they are relatively tall, typically have smooth ceilings, and are easy to manage to keep competitors seperate from inappropriate coaching. It would be a pain to have students moving tables into and out of a court.

There are work arounds. Mount your torque meter/anchor to a long board with easy hand holds. Have one student hold that as a stooge.

You might have your coach ask why the rule was implemented, I haven't heard of it being implemented anyplace else (except the judges table, that just makes sense for the reasons I mentioned).

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Re: Helicopters B

Postby gmui » Mon Apr 08, 2013 5:47 am

Thanks for the reply. The event will be in. Big university gym so it's not the court issue you mentioned. Not using the judges table makes sense but I'm not sure why a small portable table wouldn't fall into the rule that says "Teams may bring any tools and their flight log." Wouldn't a winding stooge attached to a table count as a tool?

Will need to check again...

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Re: Helicopters B

Postby Inergy9118 » Tue Apr 09, 2013 2:54 am

1). Generally speaking is there any advantage of taking a smaller size motor and doubling it over instead of simply going with a larger motor? ie). would a doubled over 1/16" motor be the same as a 1/8" motor? Will it produce the same amount of torque. PS. where is a good source to get a torque meter?
2). We have constructed about 10 helicopters so far and wondering if there is any advantage of having both rotors free spining as opposed to only one (the upper rotor) free spining while the other is fixed. Wondering if the lower free spinning rotor adds any stability. We do not seem to see any signifcant difference.


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