rrTV-PHOTO   New HD TV
HOME   rrTV-PHOTO   GALLERIES   MY GALLERY   HELP-FAQ
myHOME PM pmRR MEMBERS 301 ONLINE 28 EVENTS SEARCH REGISTER  START HERE
 
1 page239 viewsPOST REPLY
Futaba-RC . A Main Hobbies . Boca Bearings

.
.
Beginners Corner > lost tail control
 
 
nrad2000
Senior Heliman
Location: USA

couple days ago I finished building another century heli 50size. brought it to a hover - trimmed it - and did some simple figure 8's. Smoooth. about 2 minutes into the flight the heli dipped a few inches and went into a full left rudder spin. With any new heli I had the training gear on and luckly that absorbed the landing. I still had cyclic control and throttle control, but completely lost tail control. tried trouble shooting it but couldn't duplicate the tail servo to go full left. Nothing is binding - every linkage and control surface is smooth and free.

I'm trying to narrow it down to:

1) bad rudder wire connection somewhere - but why stuck in full left rudder - wouldn't it be temporary and regain control in a few seconds?.

2) electrical glitch - but why rudder only?

3) gyro - I bought the gyro on e-bay for $20 bucks - it's a JR G410T basic tail lock gyro. and why after 2 minutes of flight? I tried duplicating the problem on the ground for 10 minutes and can't get the tail servo to lock up in left rudder position.

That was a couple days ago. Physically and electronically (on the ground) their is nothing wrong. so I took it up for a spin this morning. first minute ran smoooooth. took it up 50 feet and did some basic figure 8's and smoooth. climbed around 100 feet and began a left bank and AGAIN - the heli dropped a few inches (maybe a foot or so) and went full Left rudder spin. this time I had no training gear and the heli was at 45 degrees at 100 feet. everytime the heli came around and pointed up I used forward cyclic to pitch it forward and I kept doing that until it was almost leveled with the ground. At about 50 feet I'm now trying to figure out how to land the thing. 20 feet I was worried about boom strike. 5 feet bracing my self for impact. increased pitch at about a foot. touched the ground, cut motor, and negative pitched - landed on both skids true and flat to the ground. Because of the spin when it touched ground one of the tail blade hit a rock or the ground, broke off and snapped the tail fin in half. that was the only damage that I can visibly see.

I'm beleiving this is an electrical thing - not mechanical. maybe something to do with the heli vibration. maybe bad connection or maybe a bad gyro. what ever it is - I need to figure it out before I take it up again. obviously, it will do it again - and maybe I won't be as lucky on the landing.
06-05-2008 08:02 AM
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

Chasing tail problems myself

Obviously, the belt is something to look at. With the problem not starting until a couple of minutes into the flight, it might be too many twist in the tail belt. This was suggested to me, but was not my problem.

Check for binding linkage from the tail servo to the tail. I had a minor issue with the guide and ended up not using it. I modified the tail servo linkage to a CF tube and then just eventually shifted the tail servo out on the boom to the tail (shifting CG for an AP ship).

I am presently believing that I may have binding issues on the slider linkage at the tail itself. It doesn't catch every time, but like you, after a few minutes of flying I loose tail authority. My speculation is, just that little bit of flying is enough to up the temperature on the tail assembly creating a binding condition. I land, let it cool down and it doesn't show up.

As suggested by some in this group, I am in the process of disassembling the entire tail and going over it with steel wool to smooth everything out.

I am relatively new to heli's as well, but have noticed that new parts seem a bit "tight" sometimes and can create performance problems like this. I'm trying to learn to find the balance between smoothing out new parts and wearing them out.

Anyway, it sounds like you've already done better than me reacting to this condition (taco city with a 450) and hope you have luck working through it. I am sure they'll be some more suggestions as the people in this group have been a great help with other issues I've had. Good luck and good flying.

VM

PS- Re-reading your post. Most of my electronic problems manifest themselves in an "all or nothing" kind of problem, which is to say, if your gyro or servo had a problem, it would probably make the heli simply spin. Any one else notice this in electric issues? Typically, things just "stop working".

Perfectly sliced air every time!
06-05-2008 02:21 PM
 
 
tricid
Heliman
Location: Sherman, TX USA

I've had a bad GY401 gyro cause this. On the ground everything worked perfect, and in the air it would work fine for a while, but eventually it would slowly drift one direction relentlessly until I had to bring it down. After a few days of trying to figure out why, it finally started doing it on the ground too. It would just slowly turn my rudder server to its limit and keep it there, ignoring inputs. (but only after I gave it input to move that direction once)

It should be noted it was probably my own fault. The last time it worked properly a light mist started, and I continued to fly. I probably got it wet.

I should also note ignoring the problem ended up ruining my tail servo. I leave my heli on and let the battery die when I'm finished flying, kinda to cycle it, and that drift bringing the tail servo to its limit wore out the gears in one sitting. Once I replaced the gyro and tail servo everything was just fine.

Not sure if that would be your problem though since it's also dropping a few inches, that sounds more like your belt, but I felt it was worth noting that a bad gyro can show itself in odd ways.

- Rick
06-05-2008 02:52 PM
 
 
nmrs
Senior Heliman
Location: Austin, TX

It may or may not be your gyro, but a $20 gyro off of ebay certainly raises a flag to me... Do you have another gyro (maybe on another heli) that you could stick on there and run for a test flight?
06-05-2008 03:25 PM
 
 
nrad2000
Senior Heliman
Location: USA

I'm going to check my power switch or power line area. I know that when I turn on the electronics the gyro 401 will go to full left rudder for a few seconds and then reset itself to center. perhaps i'm momentarily losing power and the gyro resets itself.

I agree the belt is a good place to check out but I have a torque drive. I will tripple check my linkages.

For now, my gutt feeling is in the electronics. will go hunting some more.
06-05-2008 03:36 PM
 
 
nrad2000
Senior Heliman
Location: USA

I have a G500t on my other heli - I'm thinking of trying it, but means I have to risk my heli for a possible crash. i'll need to take extra measures in the landing.
06-05-2008 04:40 PM
 
 
vidmarv
Senior Heliman
Location: ft walton beach, FL

Same boat

I am at the same point, as far as risking a crash. Started this thread to see if there was some way to "static" test it without risking the model;

http://runryder.com/helicopter/t436674p1/?p=3517501#RR

Hope it helps.

VM

Perfectly sliced air every time!
06-05-2008 04:58 PM
 
 
kcass518
Veteran
Location: Manhasset, NY - USA

When testing it, just don't fly so high! Hover it a couple of feet up for the ten minutes or whatever it usually takes to get the thing to happen. If the tail lets go, you can land quickly without any damage. I would try the G500T on it. I bought a voltage regulator off HeliFreak for cheap a couple of months ago - the seller claimed it was brand new, and it looked good - My third or fourth flight it went dead as a doorknob in FFF and cost me over $200 to fix the heli. I put in a brand new Arizona, and no problems since then. I won't be looking for 'bargains' anymore.
06-05-2008 05:55 PM
 
 
nrad2000
Senior Heliman
Location: USA

this morning I flew the heli with a different rx switch and a different gyro (JR G500T) and it did the same thing but this time within seconds. Again, I hit the tail and destroyed a second set of tail blades and tail fin (no more spares). I went searching around Runryder if anyone had similar problems - and i found a post where someone suggested tail drive assembly. so, I grabbed the tail hub with left hand and with the other hand tried to turn the main gear. Oh my, the main gear turned and so did the tail output gear - but I was able to hold the tail hub motionless. Their was still plenty of grab where the tail would spin.

1) could this have been the cause of my tail spin?

2) could this have been caused by my initial crash?

3) could this have been caused by this mornings crash?

I'm gonna dissasemble the entire tail and see what I find.
06-07-2008 02:55 AM
 
 
nrad2000
Senior Heliman
Location: USA

Couldn't believe it. during assembly I have forgot to use blue locktite on the set screws of the torque tube input hub. It wasn't spinning free but perhaps enough where the input shaft gets warm the size changed and loosened inflight. I don't remember my physics but i'm guessing when a shaft heats up something changed - either my input shaft or the set screws.

I'll reassemble, wait for new tail fin and tail blades. I'm still not going to rule out the possibility of electronic failure.

Next time - i'm gonna hit throttle hold and auto down. see if that helps the landing.

still, would this cause full left rudder like spin? I'm still wondering.
06-07-2008 03:28 AM
 
 
kcass518
Veteran
Location: Manhasset, NY - USA

I would guess that you've found the problem!!! If the tail shaft was not fastened tight, causing the tail rotor to spin slower than normal, yes, this would cause the heli to stay in a left turn because the tail rotor can't keep up with the torque. Too bad it took so long to track down, but it should fly like a different heli when you get it back together!
06-07-2008 02:47 PM
 
 
gadgetdude
Senior Heliman
Location: Southern California

Just curious, what RX are you using?
06-07-2008 04:00 PM
HOMEPAGE  
 
 
nrad2000
Senior Heliman
Location: USA

It's a JR R700 that I have been using for a while. Planning to retire it on Fathers Day. Been hinting the wife for a JR 9303 2.4Ghz - means I'll need 3 more receivers.
06-07-2008 06:35 PM
 
 
1 page239 viewsPOST REPLY
Modefo's RC Helicopters . XHELI.COM . Autography FlightPower

.
.
Beginners Corner > lost tail control
  UPDATE SCREEN   PRINT TOPIC Advertisers 

Subscribe to This Topic

Wednesday, October 8 - 9:30 am - Copyright © 2000 - 2008 runryder.com | email | link to rr | runryder needs cookie