S8R diagnosis of Problem with Gas Engine
Wayne, Scott, TMT, Thank you for your thoughtful comments. My goal is to reproduce the occurrence in a controlled manner. This would give an assignable cause. The trouble is lack of diagnostic tools. Your comments to a test plan that I came up with would be appreciated. This will take time to implement and test priority is key to finding the answer quickly.
Initial Response to Comments
Scott, Wayne, Regarding battery / power – I am using a 2 cell 6.6 v 2500 mah LIFE Ed Nano battery for the Rx. After 3 flights on one day, I recharged and put in 356 mah. I considered that an exceptional result. For the second day, the 4th flight, the Rx and the 1800 mah LIFE ignition battery were recharged. The ignition battery also recharged a very low amount. Is a temporary high current draw possible while in flight? How can this be diagnosed as the cause?
TMT, Regarding Loss of RSSI and Custom Settings – No warnings were given. The default loss of signal was custom set by early thinking perhaps incorrectly. The following values were used. Some I can see now were wrong. Changes here are worth testing.
Channel 3, Throttle at -75 (Just above idle)
Channel 4, Rudder at -25 (Just a slight ¼†deflection)
Channel 7, Engine Kill switch at -75 (Must have been planned for something else because engine would have turned off. This is worth testing.)
Channel 9, Gain at +25 (The gain would be increased passed center; effect not clear.)
Channel 10, Flight Mode at -100 (This would force auto-level mode on)
Channel 11 Trainer Mode at +100 (Set on SG switch, this would turn on/off slave control, but no Tx was connected.)
Channel 12, Self Test at +100 (Set on SD switch. This would activate self test only if 3 x’s passed center. However, SA switch sets to an Over-ride to Channel 12 down to -100 when throttle is active.)
TMT, Regarding Self-check method used – I set the SA switch to Channel 3 override for the throttle at -100 to ensure that I don’t bump the throttle while doing a Self-check. After exercising rudder, aileron and elevator, I switch on the SA switch and move the throttle past 25%. I then turn Rx off; radio off and then back on. Rx turned on and all functions checked again after blue LED turns off.
Wayne, I agree that using a hose clamp on the spark plug (all I can find on the net) or changing Rx’s is worth testing to checking for RF interference assuming the S8R is susceptible and the RX8R-PRO is not. Should this be set up as a Master or Slave or by itself? Obviously stabilization would be gone unless it is installed and set as a back-up redundant Rx.
Planning Diagnosis steps. (This will take some time to implement.)
1. Taxi plane on ground exercising throttle but not taking off for about 5 minutes. Repeat taxiing while switching Channel 10 full down (ALM on) and full up (ALM off). Monitor Rx voltage on Tx to see if there is any blips.
Purpose: See if problem is re-producible and see if there is any loss of Rx power.
2. Taxi plane on ground and use a metal can over the antenna to block signal. Check function of custom set RSSI as currently set and repeat with changes.
Purpose: To see what plane would do with loss of signal and impact of custom setting.
3. Attach hose clamp on spark plug to see if it is an RF problem. (Seems solid now but worth trying) Repeat taxing around.
Purpose: To see if RF is contributing to the problem. (I don’t have any equipment to use)
4. Install video camera inside and observe LED while taxiing. (Yellow light vs. green light vs. red light observations). I have a Range Video goggle and some small cameras to try.
Purpose: Assuming vibration, check LED status as it is now and see if yellow LED can be used to diagnose vibration problems.
5. Re-install Rx on metal plate replacing top plywood. Install using vibration mounts.
FYI, I ordered vibration screws and anti-vibration plate separately from Amazon to try a new configuration used for other flight controllers. About $8.00 each. Re-test taxiing w/ video camera to observe effect. (See pictures.)
Purpose: Assuming vibration, to see if there are any LED status changes with different mounting systems. Use yellow light as a diagnostic tool to show improvement.
6. Find and test engine anti-vibration mounts taxiing around. (Currently the engine is installed solid on stand-offs to the firewall.)
Purpose: Assuming vibration and LED is giving clues, use yellow light to show improvement.
7. Install different Rx’s V8R-II, (because I have one) RX8R-PRO Repeat taxiing around and observe changes.
Purpose: Assuming choice of RX is the cause, this would give insight as to whether the S8R is the cause focusing on vibration or RF as assignable causes.