Balancing sides/rubber bands

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Re: Balancing sides/rubber bands

Post by JojoCho »

CrayolaCrayon wrote:My motor stick was imbalanced. I simply fixed it with some clay :). Check the weight of your rotors and rubber bands, too!
I will try that out, thanks!
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Re: Balancing sides/rubber bands

Post by NerdyAthlete »

A bit off the subject, but has anyone had any success using O-rings when flying competitively? Im curious if the extra weight has a significant impact on flight times.
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Re: Balancing sides/rubber bands

Post by retired1 »

High winds without o rings will make it very hard to load--especially if you are loading a delicate chopper. If you wind on the chopper, then you only need one. I am a coward and would not wind on the chopper. We destroyed a good Wright Stuff airplane that way a couple of years ago. The extra weight will not seriously affect most peoples flight time. Try it without and see how you like it. Watch out for the bonus time after you get the rubber bands. Any problems loading could easily cost the loss of the bonus.
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Re: Balancing sides/rubber bands

Post by bjt4888 »

Erratic flight behavior may occur even if the motors are similar and are wound the same. If this is occurring, we have found the cause to be compression deflection of the central crossmember (the crossmember that is the bottom edge of the primary vertical stabilizer). We are finding that the crossmembers are, in some cases, very light and soft wood and the tension on the x-truss threads created by the wound motor will try to compress the crossmember and cause it to bend. If the bends on both sides are significant enough, erratic flight path may be the result.

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Re: Balancing sides/rubber bands

Post by daydreamer0023 »

bjt4888 wrote:Erratic flight behavior may occur even if the motors are similar and are wound the same. If this is occurring, we have found the cause to be compression deflection of the central crossmember (the crossmember that is the bottom edge of the primary vertical stabilizer). We are finding that the crossmembers are, in some cases, very light and soft wood and the tension on the x-truss threads created by the wound motor will try to compress the crossmember and cause it to bend. If the bends on both sides are significant enough, erratic flight path may be the result.

Brian T.
If you don't mind, could you quantify how much compression deflection would cause an effect in flight path?
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Re: Balancing sides/rubber bands

Post by bjt4888 »

Daydreamer,

If you gentl flex the FF kit motor sticks “down” (down as if they were airplane motor sticks, or flexing towards the edge adjacent to where the motor would be), you will see on the Helis with the lightest wood for cross members that the truss threads attempt to compress the cross member. Of course, the cross member can’t actually compress, so it deflects to one side or the other.

Now load a wound motor onto the motor stick and inspect the cross member. The wound motor (if loaded with minimal back off) is most likely deflecting the cross member to one side or the other.

This deflection Can potentially affect the flight path.

Does this explanation help?

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Re: Balancing sides/rubber bands

Post by daydreamer0023 »

bjt4888 wrote:Daydreamer,

If you gentl flex the FF kit motor sticks “down” (down as if they were airplane motor sticks, or flexing towards the edge adjacent to where the motor would be), you will see on the Helis with the lightest wood for cross members that the truss threads attempt to compress the cross member. Of course, the cross member can’t actually compress, so it deflects to one side or the other.

Now load a wound motor onto the motor stick and inspect the cross member. The wound motor (if loaded with minimal back off) is most likely deflecting the cross member to one side or the other.

This deflection Can potentially affect the flight path.

Does this explanation help?

Brian T
Yup, thank you! Have you been able to find a way to minimize it, though?
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Re: Balancing sides/rubber bands

Post by cheesecake »

bjt4888 wrote:Daydreamer,

If you gentl flex the FF kit motor sticks “down” (down as if they were airplane motor sticks, or flexing towards the edge adjacent to where the motor would be), you will see on the Helis with the lightest wood for cross members that the truss threads attempt to compress the cross member. Of course, the cross member can’t actually compress, so it deflects to one side or the other.

Now load a wound motor onto the motor stick and inspect the cross member. The wound motor (if loaded with minimal back off) is most likely deflecting the cross member to one side or the other.

This deflection Can potentially affect the flight path.

Does this explanation help?

Brian T
We have had some erratic flight behavior and noted some deflection in the motor sticks. On the ceiling, for the first 10 seconds or so, the two motor sticks are not exactly parallel. They seem flexed a bit. It has to be the compression you are talking about. If we back off more winds, you lose time. Do you suggest going with heavier balsa, or unwinding more to reduce launch torque?
Last edited by cheesecake on March 26th, 2018, 8:32 am, edited 1 time in total.
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Re: Balancing sides/rubber bands

Post by bjt4888 »

Daydreamer and Cheesecake,

We have used fairly conventional methods to minimize crossmember deflection. Sorry that I can't really say more than that till after our State Championships on April 28.

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Re: Balancing sides/rubber bands

Post by Blonded »

NerdyAthlete wrote:A bit off the subject, but has anyone had any success using O-rings when flying competitively? Im curious if the extra weight has a significant impact on flight times.
You must use O-rings! Please!

First of all, the O-rings, like said before, are essential to loading the helicopter safely.
Second of all, the O-rings don't have that much mass. One O-ring weighs 0.064 grams => Two weigh 0.128 grams (1/8 gram). Although 1/8 a gram will increase your time afloat, I strongly believe that you will not be able to consistently load your Chinook properly and efficiently without the O-rings. With that being said, I suggest loading your Chinook with the rubber on. That saves you 1/8 a gram.

To do this, I recommend that you attach both of the rubbers to the top of the Chinook and allow them to hang. Then, your partner will pinch the top of the rubber while you stretch it to 3-4 times length and wind to desired torque/winds. Once its wound up, pinch the bottom of the rubber (just above the O-ring) with your left hand and pull it to the rotor. Then spin the rotor's hook so that it's facing the O-ring and the O-ring can easily slide on. Once the rubber is attached use your left hand to hold the bottom part of the motor stick in place and your right hand to stop the rotor from turning. Let your partner reach down and support the motor stick between his/her thumb and pointer finger while extending their pinkie finger down to stop the rotor from spinning. Now attach the second rubber. Use your left hand again to pinch above the O-ring. Once you attach the rubber use your right hand to make a claw (thumb vs 4 fingers) to extend over the rotor and up the motor stick. Using your whole hand to stop the rotor from turning and supporting the motor stick (as high up as you can) between your pointer finger and thumb. Take your left hand and do the same thing with the other rubber, taking control of the whole Chinook, then release!

Sorry, most of this was only slightly relevant, but I thought it might be useful! Lmk if you have questions or concerns!

Best,
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