Helicopter not flying properly

[centaurix]

I have built a J&H Aerospace Hurricane 2026, and it weighs around 4 grams, but it only flies for approximately 1 minute and 30 seconds. It's stable for the first 50s, then starts bouncing up and down for around 30s because the rotor tips hit the ceiling, then descends for around 10s. Does anyone know what the problem is? I use a piece of 0.125-inch rubber, approximately 28 cm long, and wind it to around 1000 turns. Also, the covering is a bit loose, and one wingtip is a little bit off, by maybe 1-2mm. Also, I'm interested in attaching a rotating disk on top, like the FFM helicopter. Does anyone have any ideas for how I could do that?

Thank You.

[Tom-TTom2015]

Maybe Coach Brian and Coach Chuck have more info.

I also started to build the Hurricane in the past couple days. I liked the FFM ceiling disc and used it on the Hurricane. I just used the thread tying the red tube onto the MS, then everything else the same as FFM ceiling disc.

The first flight I got today was around 2:10. With 10% bonus is not tooo shabby. Might earn me a medal in some invitationals. However, the next step is to seriously learn how to fly it with the right rubber.

[bjt4888]

I have built a J&H Aerospace Hurricane 2026, and it weighs around 4 grams, but it only flies for approximately 1 minute and 30 seconds. It's stable for the first 50s, then starts bouncing up and down for around 30s because the rotor tips hit the ceiling, then descends for around 10s. Does anyone know what the problem is? I use a piece of 0.125-inch rubber, approximately 28 cm long, and wind it to around 1000 turns. Also, the covering is a bit loose, and one wingtip is a little bit off, by maybe 1-2mm. Also, I'm interested in attaching a rotating disk on top, like the FFM helicopter. Does anyone have any ideas for how I could do that?

Thank You.

Centaur,

Good job reaching out for help!

You note "piece of rubber". Is this the loop length after tying the motor or the strip length before tying? You will get very specific help from us on this forum if you can supply details with as much precision as possible.

Info that would be helpful:
1. exact weight of the helicopter
2. height of the ceiling in the testing room
3. did you watch the NFFS rubber winding video? (see Resources thread on this forum).
4a. "wingtip off"? In what direction; pitch angle of rotor tip, spar relative to fuselage, other?
4b. yes, rotating disc is a good idea. here is a google drive with pictures of various helicopter parts that my students built including a rotating disc installation. The rotating disc installation pictured in this folder also includes a vane, which your heli will not need and also has two pieces of tubing fixed to the fuselage and a short bit of tubing glued to the carbon rod between these to make sure that the disc doesn't fall off. This setup is more than is necessary and we'll probably just use a 1/2" piece of tubing glued to the fuselage side at the fuselage tip (with thread wrap) and a "keeper" bit of tubing attached to the end of the rod with the tubing given a 1/16" standoff from the fuselage by first glueing a 1/16"x3/16"x1/2" piece of hard balsa to the fuselage and then gluing the tubing to this balsa to prevent the "keeper" bit of tubing that is glued to the end of the carbon rod from touching the fuselage as the rod spins. Also, we'll include a 8/0 glass "seed" bead between the top disc and the tip of the tubing in the future. If you don't have plastic tubing, look around the craft stores and I'm sure you'll find something that will work. You could use aluminum tubing like supplied in the kit too. If you have used all the kit tubing, you can find it at Ace Hardware and at good craft stores like Michaels or Hobby Lobby.

https://drive.google.com/drive/folders/ ... drive_link

Other data that would get you a better answer:
5. Rubber motor loop length (before use; not including knot)
6. Rubber motor weight
7. O-ring(s) weight
8. Total turns wound into the motor
9. Backoff turns (turns reversed out of the motor to get to desired launch torque)
10. Maximum torque (highest value displayed on the torque meter immediately upon completion of winding)
11. Launch torque (torque after backoff turns are completed)
12. Remaining turns at the completion of the flight

Keep asking questions!

Coach Brian