JR XP8103 Issues (HELP)

[ingress43]

have a Century Hawk .30 and a JR XP8103 Radio. I have recently tried to get back into flying the helicopter after having hung up the hobby for a couple of years. At first the transmitter LCD would scramble and there would be a lot of noise in the servos. I found that the grounding screw on the internal board (which attaches to the next strap post on the front) was loose. After tighting this screw the LCD issue went away. However, the radio would still have issues with the collective. In hover mode, at half throttle the helo would sometimes drop straight to the ground as if the pitch on the blades had moved. I now have a helo that is in a few more pieces. Before I re-build and fly I need to figure out what happened. Any suggestions as to whether it might be the Tx, the Rx, or the Servos? I may send the whole unit to Horizon for testing, but thought I test myself if I can save some time and money. Any thoughts???

[hawkman]

I would bin the batterys...get rid forthwith! because depending on the state they have been kept in they can get nasty...

Dropping down? if you are flying in calm enough conditions you can get 'vortex ring state' developing....you could have a radio fault but bear with me on this......as you hover and descend, the disturbance comes up and over the blade tips....on a typical rc heli the last couple of inches make a huge difference to flight performance. The disturbed air comes up and over and ruins the lift...the heli then drops like a stone...trying to pull out just makes things worse...unless you have an insane amount of power to pull out.

The best way out is to fly forwards or sideways...and when coming down..take it slow and keep moving forwards a bit. You will encounter the same issues when descending with the wind...this condition affects real helis too.

Get some new batterys....and do a range test...antenna down...go about 100 ft away and move the controls about...you should be able to see the helis blades moving about...if not get some binos

I used to have a Hawk...great heli.

Rob

[ingress43]

Rob,

Thanks for the info. I don't know that rotor wash is the culprate in this case. Things seem to run fine while in a standard hover with little to NO WIND. Everything will be fine for several minutes, then WAMO the helo goes to ground and stays there. It isn't that the helo loses altitude because of no air under the blades, it is like I have pushed the pitch on the blades all the way down and it shoots like a rocket to the ground and doesn't bounce once it hits the ground. The funny thing is that the engine RPMs don't seem to change... only the pitch on the blades. Could it be that I have a bad servo on the collective?

I will try a new battery in the Tx, I just replaced the one on the Rx.

Thanks for the comments. Much appreciated.

[hawkman]

No problem, you could buy a servo tester...I have such a device though never needed to use it.

What system are you using? PPM or PCM?

PCM could mean fail safe mode is kicking in but this usually cuts the throttle.

I had this a short while ago...I was hovering my Predator Gasser (another century heli...Very nice!) and the engine kept cutting out...did this several times...I hovered real close and saw the throttle arm close on its own. Landed and though the battery was showing full...it wasnt.

Had to read the manual for the radio...I had noticed that this happened exactly on a minute...the radio system was locking out..only momentarily because I still had power to the flight controls.

I rehashed the charger settings and the RX battery is fine now...touch wood!

I am not saying this is the issue for you...but servos are usually very reliable...and radio gear is as well...most of it...but battery capacity can vary.

The ideal way is to stress test the battery and see what happens.

I use 4.8 volt or 4cell NiCads I dont have the gear to stress test as such but it involves the battery being put under load...and it shouldnt drop below 3.8 volt for a minute or something like that...dont qoute me on this but thats the idea.

Next time...sit the heli on the ground and dont run the engine...just twiddle the controls about and watch what happens.

Rob

[ingress43]

Thanks again Rob. I am running PCM on the Transmitter.

Are you by any chance a Patty??? You used a phrase ("touch wood") that my woman uses... and she is from Dublin!

[hawkman]

Its a common phrase in UK society, I wouldnt be suprised if its Irish in origin.

So PCM...this would have its built in failsafe. your collective pitch servo is plugged into channel 6?

Rob

[ingress43]

I believe it is plugged into Channel 6... but the receiver I have only has the slots listed by description, not number.