Broken wire-drive wire.

[marked23]

I took off from work on Friday. During my first flight, I had a mechanical malfunction 50ft in the air. I did a pirouette… good. And another… good. I wonder how fast I can pirouette? I did three really fast ones, all in a row. When I went to stop after the third one, the helicopter kept spinning! “Aww! My weekend is over,” I thought. The extra stress of doing a faster pirouette caused my drive shaft to break. I practiced for this eventuality and I knew that I had to crash my helicopter before it got close to the crowd. Behind me were 200+ fun-fly attendees. I could keep it in the air indefinitely, spinning away, but the wind was blowing it to the crowd and you just don’t let it go there. So I brought it close to the ground (about 1 foot) and then commanded it to fall to its death. By some stroke of miraculous luck (and maybe a little preparedness), the helicopter had a perfect, on the skids, not even a bobble, landing. Not a scratch on it. Experts and novices all agreed I had the best save of the weekend. And this was only Friday.

Wire drive broke. I think it was fatigued from a previous crash... Bent a little at the point where it eventually broke. That explains that.

So now I wonder... Can you get a real shaft drive system for the Hawk Sport? Has anyone ever had success with that?

-Mark

[Rodney]

Yes you can. They make a ss tube conversion kit. CN0520BS Part number.
It cost 53.95 from Century. It makes it like a whole new heli. Works really well with 401 gyro as the drive wire will flex with this gyro

[WillJames]

That Hawk is a nice chopper. :)

[ThBrtmn]

Good Save...Mark...
If you run into that situation again...Try hitting throttle hold...you have a better chance at saving the heli. However with the Hawk and no constant tail drive...Whichever way the nose is pointing when it stop spinning is the direction you you are going to auto in.... :mrgreen: I know...

[marked23]

Yes, Bart.
Others have made that suggestion as well. I've only practiced autos in the simulator. I was in no condition to give it a shot for real. Besides. I was in a fast piro already. There was only a light breeze and I only had 50ft to come down. There was very little chance that the piro would have slowed substantially in the 3 seconds I would have had with an auto.

Granted, I didn't even think of trying to auto down at the time... But in all the hindsight I've spent thinking about this in the last few days, it appears I made the only possible call given my skill level.

I'm still grinning about it.

-Mark

[rstacy]

Have you guys tried putting the 3/32 drive wire that Steve H talks about?
I put this in my Hawk and have had great results.
The whole conversion takes 15-20 minutes.
So far it is holding up well, the wind up is greatly reduced, and it is a bunch cheaper than converting to the shaft drive.

[ThBrtmn]

Glad you were able to save it Mark no matter how it was accomplished...Thats the important thing.
Just start practicing using that throttle hold though...I have heard from others that it should be second nature when you run into a hairy situation. Especially when you start getting into the heavy 3D. Ive seen numerous pros loose a crown gear in the tail or something and hit the auto switch and regain control to save the bird... but most inportantly where the heli lands... :mrgreen: I have also seen the reverse where the manuever was too intense to save the heli but throttle hold HELPS keep it from doing alot of post impact damage when it meets and greets mother earth. FUNKY CHICKEN BABY :lol:
Keep practicing those autos on the sim...Youll never stop once you do a real one.
Heres how I learned to really do them after I was proficient on the sim.
First, practice your desents and angle of desent to bring the heli right were you want it.
Second, once your comfortable with that, practice hitting your throttle hold a the top and then flip it back on at the bottom of the auto to bail out. This will give you a good feel for the full auto all the way to the bottom before you flip the switch.
Finally...When you feel all the stars line up and feel/hear you have enough headspeed... leave the switch in the off position :shock: Trust me...you will know when this happens.
Enjoy.

PS. Ray,
Does that bigger wire get any windup at all...? How does it feel.

[rstacy]

Does that bigger wire get any windup at all...? How does it feel.


You can feel wind up by holding the main rotor and twisting the tail.
I could make it be a problem in flight but I dont.
540s show the main gear to be the weak link and not the drive wire.

I could not get this combo to work right until I put a better gyro and servo on the tail. Remember that the gyro and servo cost more than the heli!

Now in flight, I am pretty happy with the performance. I can not run the gain as high but I dont care. For sport flying and mild 3D it works very well.

I think I would stick with the heavier wire over the shaft because

Its easier
Its cheaper
Repair or replacement is a breeze

[marked23]

Where do you get this heavier wire?

I upgraded to a tail mounted servo before my first flight... The 8700G no less. And my gyro is the JR g500t, so I'm good there too.

-Mark

[rstacy]

Where do you get this heavier wire?


Local hobby shop.

[marked23]

Oh, you mean I have to put the flats on myself? ...and bore out the tail pinion receiver for a larger wire? Hmm.. Not sure I trust me to do all that correctly, but I'll look into it.

I have to imagine that it makes a difference what metal is used. I mean a larger diam. wire made of a different metal could have the same tortion properties as the original wire, or maybe even worse. A hard spring steel might be pretty good.

-Mark