Helicopter Testing

[Orange714]

I guess it does wobble when it comes down, but when it goes up it shoots up. Yes we're using competition rubber 3/32 inch from freedomflightmodels. We're using lube, but I have no idea if it's silicone based. It came with the rubber we bought. How long should the rubber we're winding be? Our rubber tied together is about the length of our helicopter which is about 13-14 inches.

[thsom]

If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.

[thsom]

If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.

EDIT: Sorry for the double post... literally... i don't know how to delete them

[illusionist]

If I were to use solid balsa blades. what cross section? is 1/16 ok or too thin or to thick? I can only by from my local hobby store because i have 3 or 4 days to make one.

1/16 might be a little too thick in my opinion.I would stick with 1/32. The biggest factor is weight. With the traditional frame-and-covering design, you only have 1/16 around the edges. Using a 1/16 solid blade would weigh a ton. 1/32 has enough strength for these helicopters and is somewhat light enough.

[jarrred_1415]

I guess it does wobble when it comes down, but when it goes up it shoots up. Yes we're using competition rubber 3/32 inch from freedomflightmodels. We're using lube, but I have no idea if it's silicone based. It came with the rubber we bought. How long should the rubber we're winding be? Our rubber tied together is about the length of our helicopter which is about 13-14 inches.

you need more torque throughout the flight, increase the width of your rubber or make a double loop of the 3/32 you have although i suspect that it might be too much. FAI website sells a .154 width that would probably work very well based off what you're saying

[Orange714]

you need more torque throughout the flight, increase the width of your rubber or make a double loop of the 3/32 you have although i suspect that it might be too much. FAI website sells a .154 width that would probably work very well based off what you're saying

Thanks for the response.
We've been double looping the rubber band, but it still only stays in the air for 15-25 seconds...
I thought that the rubber band should be thinner, but our coach is unwilling to buy anymore, mainly due to shipping costs. What should we do? Make the rubber band longer and then just wind it a lot? In hopes that the greater winds will help it fly longer? Or should we go back to a single strand of 3/32?

[jander14indoor]

OK, as has already been said on this forum. After hitting min helicopter weight the next key to long flights is matching the rotors to the rubber motor. You can vary both, or hold either steady and vary the other. We tend to vary rubber because it's easier to play with (if you have a rubber slicer) than changing the rotor. But you CAN do it the other way if you are REALLY stuck with one thickness rubber.

OK some general rules of thumb on interpreting rubber results.
If you shoot to the ceiling then come down fast with lots of winds left, you need to go to fatter motors or SHORTEN your current motor, not both at once. This sound counter intuitive I know, but it will lengthen flight times, if not optimize them. The problem is you are climbing on peak torque which disappears quickly and you have no stamina on the 'average' torque. Fatter motors of the same weight will give you some 'cruise'. Shorter motors reduce weight and let the motor provide enough torque to fly for a little while longer. Note INCREASING the length of your motor in this state will NOT increase fight time. You are increasing total flying mass without increasing cruise torque at ALL.

If you shoot to the ceiling, bounce around awhile and land with NO winds left, you need thinner motors or LONGER motors, don't change both at once. You have excess power even in cruise so can use a thinner motor, it will take more turns, be lighter, and fly longer. Alternatively you can use that excess torque to carrry more mass, more motor, more turns, longer flight.

OK, here's this years campaign on why torque meters are VITAL for these events. For any given total mass, it requires a specific torque from the motor to the rotors to provide enough lift to cancel that mass. Your motors should be of sufficient thickness to lift the total mass during the cruise portion of the motor wind down. If you don't have a torque meter you CAN'T figure this out, can't manage it, and can't really optimize your winding. You can't even really understand what I mean by cruise because you can't plot winds vs torque to see the peak torque I'm talking about vs the cruise torque. You also can't see if one rotor design is better than another. The best rotor design is the one that creates the most lift for the least torque.

Now, I know teams have been successful (fly one minute plus) without a torque meter. The teams that understand and use a torque meter will move to the top of the heap faster.

Jeff Anderson
Livonia, MI

[eta150]

I'm flying ~2:10 without a torque meter...That being said, we're using one from now on.

[jander14indoor]

Yes, you can do well without a torque meter, but you'll do better with one. Opens up all kinds of areas where you can take better data, do better comparisons, and start talking quantitatively about things you are probably doing qualitatively now, and that's science folks.

Note, I'm not dissing qualitative, you can do a lot with careful qualitative work, and that's science too when done correctly. But numbers let you do so much more.

Jeff Anderson
Livonia MI

[lucwilder42]

How do you effectively use a torque meter? Do you do tons of static testing on rubbers or do you fly? I'm confused as to what data points give you this cruise torque