Finding a lost model with Taranis ( or other ) Telemetry

Some time ago Bruce Simpson of RC model Reviews mentioned using the Taranis Telemetry to find a lost model. I have used it several times lately so thought I would pass on this tip.

The idea is that the lowest signal is when your antenna is pointed directly at the model – which is why you fly with the antenna at 90 degrees ( did you know that ? )

If you have a telemetry enabled receiver ( a RX battery voltage display is a good indicator ) then you can get the Taranis to display the strength of the telemetry signal from the RX to the TX. This is known as the RX RSSI.

If you stand with the antenna pointed straight out and slowly rotate 360 degrees then when the signal is at its lowest you are facing directly towards or directly away from your model ( slight rub there ).

The screen below shows the default RX RSSI



You can add a more useful RSSI reading to the telemetry screen using Companion as shown below



As you get closer to the model you may need to enable range check mode to reduce the signal strength to see a discernible difference. In this case it is the RSSI in the pop up window that you use to gauge the signal strength.


This method also works on other Telementry enabled transmitters. I helped a club mate with a very posh Jeti transmitter to find a model last week but the Jeti has 3 4 antenna built into the handle so the directional aspect was not as good. He did find the model by walking around until the signal peaked and then going to range check mode to narrow it down further.

Guest Post : Marc Merlin : Taranis 6 channel with throttle and crow combined on one stick.

Marc Merlin contacted me with his modified config a the 6 channel motor glider asking if I would post it here. His post is below :

I owe huge thanks to Sean Cull for posting his detailed configuration here:
I encourage you to go look at his detailed explanations if mine seem too short. While they don’t apply to my model config, he explains very nicely how things generally work, and this is where I learned most of what I know about Taranis programming.

I’m sharing my 7 channel glider config because it allows you to setup your flaps asymmetrically where they go down more than up, or only down. You decide how you want to set yours up and you only need to change the subtrim in channels 6 and 7, something that was very non obvious to me when I was learning how to program my Taranis.

My setup is also different from Sean’s by having the throttle stick control crow flaps from 0 to 45%, nothing from 45 and 55%, and then throttle from 55% to 100%. This allows you to use a single power lever to slow down from gliding, or add power to gliding, middle being neutral. No switches to flip to switch from crow flaps to motor power, which is very handy if you have to cancel your landing as the last second.

You can read more about it and get the config files here:


Why won’t my Taranis bind and the saga of EU Firmware ETSI EN 300 328 V1.8.1


The EU has introduced an improved standard covering R/C transmitters called ETSI EN 300 328 V1.8.1 . This came into effect on the 1/1/2015 although there was quite a lot of warning in advance.

This change has a new constraint that a Tx that has just been turned on must first listen to any frequency before it broadcasts on that frequency. This helps to determine if the frequency is in use by another person – this seems quite sensible and makes the frequency management more robust. This is known as Listen Before Talking ( LBT ) and is in section

The internal Taranis transmitter module ( not the OpenTx part ) did not comply and FRSky issued a firmware update at pretty much the last minute. Legally this is only required for new Transmitters sold after 1/1/2015.

But here is the rub : A Transmitter working in D16 mode ( the mode required for telemetry ) can only work with receivers that are using the same firmware.

So a pre 2015 EU Tx will not work in D16 mode with a shiny new receiver and vice versa. The quite useful chart below is floating about ( Kunde means user up-gradable ).

Note that it is not clear at this time if receivers and transmitters sold outside of the EU will have the “2014” or “2015/ EU” firmware – so if you have a pre 2015 Tx you may be able to buy receivers from outside of the EU to keep everything “Non EU”


So … if you want to use D16 mode ( more later ) and you want to buy more receivers you need to have ALL of  your receivers and Txs either using the EU firmware or not using the EU firmware – but they must all be the same.

I choose to upgrade my Tx and Receivers. You need to purchase 2 cables and then make adapters. For the Tx the process is described here. For the receiver the smaller X4R receivers need a molex adapter ( the cable was in the packet ) but the X8R receivers do not.

My article on the X4R upgrade

Once you have made the adapters the process is not too bad. There is also work in hand by the amazing OpenTx Community to allow the Tx to be upgraded via OpenTx Companion – this is possibly in version 2.016. This will also allow the Receivers to be upgraded from a wired connection tot he Tx which will be useful for people without a Windows PC ( not sure how Mac users are affected ).

So if you are in the EU what are your options are :

=> Don’t but any new receivers and life is fine

=> Use D8 instead of D16 if you do not need telemetry ( including battery indication ? ). You may also loose the ability to bind a profile to only one receiver ( can anyone clarify ?)

=> Downgrade any new receivers to the 2014 firmware

=> Only buy receivers from outside of the EU ( not 100% sure on this being a fact )

=> Upgrade everything to the 2015 firmware.

A couple of last points :

1) make sure you get the latest 2015 firmware. The is the original 2015 firmware and there is a “bug fixed” version – I think it is highly irresponsible of FRSky to continue to allow the buggy software to be downloaded.

2) remember to reset your fail-safes after flashing the firmware – even if they are configured via the TX.

Please let me know if any of this needs improvement




Quick note on updating the Firmware on a FrSky X4R Receiver

downloadThere is a good thread here –

The 4 things I would add are :

1) do not power your receiver from a battery. It will get power via the USB cable.

2) you will need to make an adapter using the small molex (?) plug supplied when you bought the receiver. Use the yellow, red and black cables.

3) The software tool you need is a pig to find. Look for the “Upgrade Lite-S.Port Telemetry” under Download > Tools

4) Be careful – there seems to be both the original EU firmware and a “bug fixed” version of the firmware on the site.

Note : you will need to re-activate your failsafes again after flashing the firmware – even if you configured them via the Tx or OpenTx Companion.

Hope that this helps, Sean

Aileron Differential / Adverse Yaw and a touch too much cleverness – Hard Lesson Learned and



Update – while everything below still stands the cause of the problem was worse than I thought. In introducing a curve for the aileron differential I had reversed the servos to make it work BUT I had not tested “basic or panic” mode afterwards – and so the aileron controls were reversed in that flight mode – which is kind of ironic. This has made me even more convinced that a basic / panic mode with no mixes is not necessarily a good idea or needs to be done and (re)tested with as much care as the other modes.

I read an excellent article in the BMFA journal ( issue 121 , unfortunately not on-line ) about Aileron Differential / Adverse Yaw but unfortunately never got around to doing much about it until this week. Essentially this is where symmetrical deflection of the ailerons causes too much drag on the lower aileron – just like dropping a flap on one side of the model only.

Last week when I set up my new Hobbyking Phoenix 2000 ( review coming soon )  with quite large aileron throws so that I could use crow braking / spoilers. When I looked at the amount of downward deflection of the ailerons it was very significant and alarm bells rang in my head. I used curves on the Taranis to reduce the downward deflection to 40% and this seemed to work really well.


In my Taranis setups I usually have a basic mode with no mixes as a fallback in case I have programmed something wrong. I have always been quite proud of this feature – until today.

As I circled around for landing I accidently knocked the switch into this basic mode. I wasn’t too worried as it was a simple landing and I didn’t need engine or braking. Unfortunately during the slow turn the model stalled, dropped a wing and dived into the long grass.

What had happened was that the 40% limit on the downward aileron deflection had been removed and the excessive downward deflection on the inside wing during the turn had created so much drag that the wing had stalled.

Thinking back to my first slope session a couple of weeks ago when a crashed another plane the symptoms were very very similar.

So the lessons learned :

1) aileron differential is very important

2) you can be too clever when programming transmitters sometimes

I will update the 6 channel Taranis eepe this week