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Mikado Modellhubschrauber . GrandRC . CanoMod

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Miniature Aircraft Nitro/Gas Helicopters > Tempest RX interference issues
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

ive got a tempest 3d...but with a carbon frame instead of the G-10...its running a new os 91 hyper, SB-19, 9252 cyclic, 9253 on throttle with a GV1, 9253 on the tail with a GY502, 710mm Vblade mains and 105 v tails, all powered by a Li-ion 4cell fromeco with the arizona regulator...heli is beautiful...flys like a dream.

UNTIL...

the other day i had removed my 148DP futaba RX and installed a G3 5014 RX with the short antenna...did a range check...started...and went into a hover...POW...big twitch...i literally shoved it downward and snapped the landing gear to park it NOW!!...did the repairs...removed the RX so i could do some thinking...and went back out for another flight...all was well.

i then bought a 6114 FASST RX for it just a few days ago...did my install and went back out...durring spool up im getting that same twitch...the swash moves aft cyclic at about 1400 head rpm...i can spool past it...it seems to get better...but its still there and still twitchy...literally cant hold a hover without major concentration to keep an eye on things and correct it.

where is the interference being generated...does it sound carbon related???...or more likely a bearing???

ive been around helis for a long time...and R/C in general even longer...but this one is pretty illusive.

thoughts...opinions welcome.

Todd.
07-24-2008 10:16 PM
HOMEPAGE  
 
 
hyflyr
Senior Heliman
Location: Baton Rouge, LA

Have you tried putting the old rx back in to see if the twitching goes away? What is the voltage setup on the fromeco regulator? Not that is should be an issue but maybe the fast response times on the new rx's is creating voltage glitches. May want to go to a simpler power source to remove the power supply or put a fresh lithium pack on the heli. If the glitches are still happening on the FASST RX I would look at the power supply more than the RF. I would check the servo leads very carefully since the leads had to be moved from one RX to another. Maybe some wire stress issues.

Scott
07-25-2008 05:40 PM
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

thanks for your time...

...the 148dp works fine...thats one of the strange things...the sensitivity makes it better sure...but it still must be "seeing" hits of some sort im sure.

the regulator has been backed off to 5 volts...still the same...

i will try a simple NIMH system that i have around and see if it solves it.

ive also ordered a bearing kit for it to do an overhaul

thanks again

todd.
07-25-2008 05:49 PM
HOMEPAGE  
 
 
junkpilot
Senior Heliman
Location: Summer/Alamogordo N.M. ,Winters/ Tucson

Interference

Coolflyer;
If the problem exists at 1400 rpm and not at other speeds I would suspect loose connection somewhere in the system. Furthermore if the glitch always affects the heli in the same direction ( aft cyclic ) that would seem to eliminate power supply.
A bad feedback potentiometer in one of your servos will cause glitches on that channel only.
In the intrest of locating the cause I would install the NIMH battery but I would also install another servo.
In the days of JR Century 7s I had one that glitched the collective servo only, Turned out to be the circuit board on the receiver.
Good luck; Junkpilot

When you fly JUNK it's hard to tell when you've crashed!
07-26-2008 04:21 PM
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

that sounds really logical...great points...i will indeed swap out the 'elevator' servo as that was clearly the twitcher...

good stuff

todd.
07-27-2008 03:06 AM
HOMEPAGE  
 
 
bparro
Veteran
Location: indianapolis,in

sounds like what was happening to mine when I had a wire wearing on carbon. 2.4 should not have any type of glitch or interference from a bad bearing or other metal on metal contact. But, when something connected to the power system shorts on the frames...lockout. A loose connection or bad servo are also things to check and test.

Miniature Aircraft USA, V-blades
07-27-2008 04:28 AM
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

more great info...thanks

im 100% sure there are a few bearings that are shot...i have no choice but to fly in a dirty area...so the bearings are abused...i have ordered a bearing kit...its getting some attention from the ground up...but now that i have a better idea on possible culprits for the twitch...the electronics will be really checked.

thanks guys
07-27-2008 04:37 AM
HOMEPAGE  
 
 
lfalsetto
Veteran
Location: COLORADO

pull all the servo wires out I will bet you routed them inside the frame and one wire has chaffed.
07-27-2008 08:51 PM
HOMEPAGE  
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

BINGO!!!

elevator servo indeed does have a chafe on the signal lead right near the wire going into the main grommet at the servo case...it looked as though the grommet was keeping it shielded...BUT...WRONG!!

thanks guys...

todd.
07-28-2008 01:12 AM
HOMEPAGE  
 
 
bparro
Veteran
Location: indianapolis,in

 Some of that black mesh material will protect those wires. I use that stuff anywhere the wires might chafe.

Miniature Aircraft USA, V-blades
07-28-2008 02:27 AM
 
 
hyflyr
Senior Heliman
Location: Baton Rouge, LA

I have used the mesh sleeving and have found that if the frame edges are sharp enough to cut the servo wire insulation then the mesh gets cuts as well. The stuff looks great but the best option is to sand the frame edges where the wires touch. Preferably sand the frame edges prior to assembly. Another option is to slice fuel tubing and CA over the edges.

Scott
07-28-2008 04:19 AM
 
 
CoolFlyer
Heliman
Location: Rankin Inlet, Nunavut, Canada

im going to put a few layers of heat shrink right in the spot where the leads run thru the frame...ive got the bearings on the way so im just going to tear it apart and do it all at the same time.

i do have some of the braided sheild as you mention...but not sure if its the right stuff for this location...a few layers of heat shring will ensure its safe.

thanks again.
07-28-2008 04:57 PM
HOMEPAGE  
 
 
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Miniature Aircraft Nitro/Gas Helicopters > Tempest RX interference issues
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