I was flying a motorized glider using a new G-RX8 receiver and a neuron esc so I had telemetry. After about 5 minutes I lost complete control and the plane spiraled into the ground. The spiral was caused by incorrect failsafe settings for the way I had configured the ailerons so I understand that. What I am concerned about is that telemetry shows that RSSI was varying between 52 and 47 throughout the flight and then suddenly dropped to zero, which precipitated the failsafe and ultimate crash. Telemetry shows esc and rx voltages remained normal until ground impact some seconds after loss of RSSI. After recovering the aircraft, now in several pieces, RSSI was fine. Control surfaces still attached functioned normally. Just wondering what else I could troubleshoot.
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RSSI Loss
- Thread starter bob_stan
- Start date
RSSI is the signal strength received by the receiver and then reported back to the transmitter as one of the Telemetry sensors. Not all Telemetry sensor are transmitted back to the TX in real time, so this may explain why some sensors remained active. But once the RSSI is lost the Telemetry connection is also lost. Did you perform a range check. Range check allows you to check the performance of both the receiver and transmitter. It does this by reducing the TX power significantly and under these conditions you should be able to achieve at least 50 meters of ground range before you commit to flying. The RSSI value of 52 to 47 db sounds very low, how far away was the model with that value. How did you have the receiver antennas dressed at the model end, did you have servos or a battery located close to the antennas, are you using a carbon fiber model.
You did not specify your transmitter type or operating firmware, are you using an FRsky Transmitter.
You did not specify your transmitter type or operating firmware, are you using an FRsky Transmitter.
Sorry = X20S running ETHOS 1.5.9. Glider has a foam body. Range check was fine. I would estimate the model was about 1/2 mile distant. I had done quite a few similar flights this year with the same transmitter although I just upgraded to 1.5.9 and it was only the second or third flight with the GRX 8.
I am running the same hardware and firmware version without issues. So this may have something to do with Antennas on your TX or receiver. Have you set the antenna on your TX to internal or external. Can you include an image on your receiver location and the way you have dressed the RX antennas. Was the model wet or flying behind or near wet tree leaves. Water is the enemy of 2.4g. That's why Micro wave ovens operate at this frequency. Is it possible the Glider battery or a connection failed. Are you monitoring your lipo pack voltage via the telemetry from the neutron ESC.
The lipo pack voltage seemed ok with no excessive drop. i am beginning to believe it may have been due to the receiver/antennae locations which were very close to the battery and servos. Picture not possible due to damage but I will pick a better location on the next one. Thanks for your advicce.
As an aside, I model large scale boats and often the receiver is deep in the hull well below the waterline. As such, I have gotten into the habit of using FrSky extended antennas. They are tip loaded and available in several lengths. It has the added advantage of moving the tip of the antenna much further away from the receiver and power sources, ESc's, servos, ect.
I position my antennas one either side of the fuselage, in a piece of heat shrink tubing as a loose fitting guide to hold the antennas in place so I simply slip the antennas into the tube. A drinking straw also works for this. Its way of holding the antennas without putting strain on the receiver end. Antennas need to be well clear of any other objects if you want the best range. How are you monitoring the Lipo voltage.
I am using a Neuron ESC. I am assuming its ESC Voltage is the same as the LIPO voltage. Seems to agree pretty well with before and after flight LIPO checks with an external checker. Liked your idea about the heat shrink for routing antennas. I had some small diameter fuel line tubing which I have now used to route the antennas and seems to work well. We'll see how it flies.
The low RSSI just before seems pretty suspect. But don't count out the ESC or its wiring connections. If it shut down power to the RX....
Not the same, but I chased big problems on a gas plane for a full year - engine, batteries, receiver, TX all replaced....and it turned out to be an intermittent power switch.
Not the same, but I chased big problems on a gas plane for a full year - engine, batteries, receiver, TX all replaced....and it turned out to be an intermittent power switch.
I agree, this may well be the actual cause of the failure.
OK the mystery continues. Another crash. This is a different plane, neuron esc (a different one), Archer SR9 ACCESS receiver. Range check OK. Plane took off. I began a right hand turn and progressively lost control. At the time the plane was about 200 feet away. As everything stayed hooked up, telemetry continued. You can see a rapid drop in RSSI until impact. Then as I walked towards the plane you can see the RSSI increasing again. I have no idea what is going on. The only other possible factor is I have a Marco Polo plane finder attached. (and have used it on all planes for the last couple of years but not with the new receivers). It operates in the 900mhz band I believe. I am only using 2.4G and have the X20S 900 transmitter turned off. I have attached the RSSI log.
Attachments
Have a look at the VFR sensor to see what level of control you still had. From the presented RSSI it does not look like a radio failure.
I'll second the VFR (Valid Frame Rate), it is a better indicator than RSSI. (VFR uses RSSI and the quality of the packets received.) A strong RSSI and a weak VFR is a bad sign and totally possible. This would indicate interference at the field.
Hope this helps.
Also strongly suggest ground range checks before any more flights.
Hope this helps.
Also strongly suggest ground range checks before any more flights.
