Haven't got my radio yet and already loving OpenTX

[jseyfert3]

I'm getting back into the hobby after a ten-year break. Originally did it for a few years as a teenager with my dad. I was last using a JR XP6012. In 2012 I bought the FrSKY DHT-U and used it to convert the JR radio from 72 MHz to 2.4 GHz. This was before FrSKY released their first radio, at this point I believe they were taking pre-orders for a not-yet-released radio. Now coming back into it I started looking around and there were so many options.

It seems most of the guys at the club I'm in use Spektrum, and a few used the RadioMaster. I looked up RM and wasn't thrilled about some things, primarily QC, but was interested in the multi-protocol support, for Spektrum for the tiny BNF planes such as the Turbo Timber UMX that use integrated receivers. Then I quickly realized I could get an FrSKY radio and plop in an RF module for Spektrum. So I eventually decided to go with the Taranis SE, primarily because I wasn't thrilled with how Spektrum and others limit you to a certain number of channels/features by price, and overall inflated prices in general in comparison. I purchased a Lemon RX DSMP module for any BNF Spektrum planes I buy. I plan to use FrSKY receivers for the planes I get that do not have integrated receivers (which will be most anything that's not an indoor flyer).

My radio arrives Wednesday but I started digging into OpenTX in preparation, and I LOVE it already. It has complete flexibility. Some things I'm really looking forward to:

• Trainer use: I plan to keep the JR radio as a slave unit for buddy box when my friends inevitably want to try flying my planes. You can do clever things like only partial control passthrough, such as leaving throttle control on the master while the slave controls the other three remaining primary controls (or limit any other controls this way).
• Extreme mix flexibility. Lots of people talk about how hard OpenTX is, but after a lot of reading I agree with experienced people that it's just different, and while it has an admittedly high learning curve, is actually easier once you learn it because there are no limits to what you can do.
  • Just looked at the JR and while it has some per-defined mixes like rudder/aileron plus 4 mixes for any channels, it certainly is nowhere near as featured, and honestly harder to set up. Plus in general there's the whole hold these buttons on power up to access this sections of settings instead of just having a bunch of clearly laid out pages like OpenTX.
• Voice feedback: My memory isn't always the best, and I can see forgetting which switch is which. But voice feedback will eliminate all confusion. Flip the switch and have the radio say "armed" or "flaps full" or "stabilization engaged".

My goal was one radio, for both the indoor Spektrum airplanes I want to get and everything else I want to do outside, and this should do it, no problem. Now if only I could convince my dad... He had been paralyzed with indecision on what he should do, as he had one JR 72 MHz radio with a couple receivers, one plane that had a Spektrum Rx (plus some indoor BNF planes he wanted to get), a cheap Futuaba radio that is one of those ones that's bundled with RTF planes (such terrible radios), and a Taranis QX7S ACCESS radio he had bought last year but hasn't yet used. So I recommended he just use the QX7S as his primary, and that he can get a Spektrum RF module for any Spektrum planes or receivers he has, and replace all the 72 MHz stuff with FrSKY receivers. So somehow with that suggestion which seemed very logical and simple to me, he promptly ordered a Spektrum DX6E and I was just like . This especially doesn't make sense to me given he's planning on keeping the QX7S, so the Spektrum RF module seems like such a better choice vs having a DX6E and needing to cart around two radios plus keeping in mind two entirely different ways to program the radios. You can lead a horse to water I guess...

Anyway I'm excited. My radio and my new Turbo Timber UMX arrives this week, my plan is to get it programmed and fly it at the club's indoor fly this upcoming Sunday. I've already located and bookmarked a detailed post on RC groups for programming the Spektrum BNF planes to an OpenTX radio, so I'm not expecting any issues getting that set up.

 

[HENNY]

With so much excitement take a relaxant before you fly.

 

[Konrad]

I have a student that has much the same enthusiasm. He bought an X20 even though he has never seen Ethos. (I made an off the cuff comment that it was the top of the line radio and that Ethos and ACCeSS was the future of FrSky. I'm now playing catch up to learn Ethos). He also bought a Spektrum plane (Hobby Zone Carbon Cub). I wanted to convert that to a FrSky, but he wants to try gyros. So we (he) bought an MPM* for the back of the X20.

This is again forcing me to do things I don't like to do. That is learn to use the TBS MPM. His computer is under an enterprise lock down so it is up to me to get the TBS MPM to talk to the FrSky radio. It isn't too bad other than my computer as way out of date and needs a hole plethora of updates.

You haven't mentioned what version of OpenTX you are using. Many of the later version have a setup wizard that have a lot of basic mixes and setups already defined.

* I'm not happy to use a TBS MPM as it is not fully complaint with the USA FCC type certification requirements (it is not fully legal in the USA. This is like being partially pregnant). Please let us know how the Lemon module works for you.

 

[jseyfert3]

I have a student that has much the same enthusiasm. He bought an X20 even though he has never seen Ethos. (I made an off the cuff comment that it was the top of the line radio and that Ethos and ACCeSS was the future of FrSky. I'm now playing catch up to learn Ethos). He also bought a Spektrum plane (Hobby Zone Carbon Cub). I wanted to convert that to a FrSky, but he wants to try gyros. So we (he) bought an MPM* for the back of the X20.

Ah. My Turbo Timber has an integrated Rx/ESC, so it's harder to upgrade. Is the flight controller that comes with the Carbon Cub only compatible with Spectrum receivers?

Also, I did briefly consider the X20, but it was a bit more than I wanted to spend on a radio and EthOS seemed fairly new, while OpenTX was well established, so I decided to just go with the Taranis SE. Maybe I should have gone with the X20 but I doubt I'll be disappointed with the Taranis.

You haven't mentioned what version of OpenTX you are using. Many of the later version have a setup wizard that have a lot of basic mixes and setups already defined.

That's because I don't have the radio. My plan was to put the latest version of OpenTX on it once I received it.

* I'm not happy to use a TBS MPM as it is not fully complaint with the USA FCC type certification requirements (it is not fully legal in the USA. This is like being partially pregnant). Please let us know how the Lemon module works for you.

Yeah, I realized the MPM modules were not FCC compliant and I didn't like that. Plus it seemed everywhere I looked they were out of stock. With some further seaching I found the Lemon module, which was FCC certified. It only had Spektrum support but I only plan to use FrSKY and Spektrum so I don't need two other protocols anyway. I'll update here once I have experience with it.

 

[Konrad]

Yes, the Horizon Hobbies products are locked to Spektrum universe.

I too was surprised that he got a X20. Based on historical prices with RC radios even the high end X20 is still very economical.
My last FrSky TX purchase was a Taranis 2019 ACCeSS and it is lacking for nothing when it comes to my $2K gliders. Like I said I was surprised my student purchased the X20 as his first TX.

For DSMX protocols I'm looking forward to a report of your experience with the Lemon module.

 

[Nigel]

I've flown a few Spektrum planes with the DM9 module, I'm pretty sure it was just TAERF then mode select (Off, AS3X, SAFE). The best part is being able to do all the complicated mixes on ultra micros.

 

[jseyfert3]

For reference the back of the Lemon DSM2/DXMX module that just arrived today.

Link to the FCC approval page: https://fcc.report/FCC-ID/2ATBKDSMPSDR

If I read the reports correctly this appears to be a 10 mW module? And I’ve read most 2.4 GHz radios put out 100 mW? So in that case maybe not the best to use the Lemon module to try to fly a sailplane, but indoor or close outdoor flight should be fine, which is my only intention with this module. https://fcc.report/FCC-ID/2ATBKDSMPSDR

Report Sunday, if my radio arrives in time and I am able to successfully bind it to my Turbo Timber UMX.

 

[Nigel]

Definitely do a range check. Lemon stuff can be hit or miss.

 

[jseyfert3]

Yes, the Lemon is much lower power per the FCC filed test report:

Vs the Taranis FCC filed test report. What actually surprised me the most here is how much the FrSKY power output drops near the upper end of the 2.4 GHz range vs the max near the low end.

 

[Konrad]

I see that the ID plate lists for an EU rating. I suspect that Lemon is keeping the RF power low to meet EU requirements.

Historicaly I've had much better performance with Lemon receivers than Spektrum receivers. Off the top of my head I've had poor range issues with 2 Lemon 4ch DSM2 RX, and I've had 2 dead gyro equipped Lemon RX's. That is 4 bad RX across the purchase of over 3 dozen receivers. I've had much the same number of failures with SpeKtrum* but over a far smaller population (like 18).

Always do a range test with a new set up and I highly recommend doing one at the beginning of each flying session.

*Horizon Hobbies has been very good with all my Spektrum warranty claims. Some of these RX performance issues were back in the early days of the introduction of 2.4 gHz.

 

[jseyfert3]

It looks like it will not be Sunday for my radio review. My Aloft order shipped USPS in two packages. The radio in one and the rest of my order in a second.

Well, the second package arrived yesterday at the Madison, WI distribution center, got to my local post office, and is now on the delivery vehicle.

The package with my radio arrived in the San Antonio distribution center yesterday. Must have gotten on the wrong truck or plane out of California.

 

[jseyfert3]

Scared myself a bit. Got my new radio. My firmware installed was 2.3.0. I figured before I started getting everything setup I'd flash to the latest firmware, 2.3.14. Downloaded Companion, configured my radio as the XD9+ 2019, let the app download the correct firmware. Instructions for flashing didn't quite match Companion 2.3.14, so I was poking around trying to figure it out. I misread the part on open-tx.org where it said "Installing the driver is only needed when you want or need to flash your radio directly from the PC. The Taranis models all have a bootloader that allows flashing without these drivers. For flashing a Horus TX or if you need to recover your Taranis, you will need to install these drivers." I thought it said it wasn't needed for Taranis, and tried to flash the radio without the driver installed with the radio in bootloader mode. It said it finished, but when I rebooted the radio it refused to turn on, even to bootloader. After a bit of frantic searching I followed Method 3 on this site, and after installing the STM32 driver I was able to use Companion to flash the firmware. This time, in addition to the bar I got a lot of text saying what was happening, which didn't happen before. After flashing, ejecting the radio (which I didn't think to do the first time), and putting the battery back it it booted up. A check of the menu and we're at 2.3.14 now. Crisis averted!

It's much too late already though, so I'll fiddle around with setting up my Turbo Timber UMX tomorrow after work.

 

[jseyfert3]

I've got everything configured and working, based off a setup guide I found on RCGroups that had me set limits to ±80% since that equates to ±100% on Spektrum radios (except flaps at ±72% since the manual specs ±90% for flaps and 80% of 90 is 72). Control surface deflection seems good, but unfortunately the manuals for these BNF planes only spec Spektrum channel limits, not actual control surface deflection measurements. I could also compare to one of the numerous Turbo Timber UMX planes at my local club, since most members use Spektrum radios. Nothing is binding up though. Got it set up with the SAFE system on/off on switch E, and flaps on the right slider. 6 minute THs countdown timer as the recommended 6 minute flight timer in the manual, plus a persistent THs countup timer, the latter because I wanted to track approximate total flighttime of the airplane, and it seemed I likely wouldn't be spending much time flying this airplane with no throttle, though I understand that wouldn't be a great way of tracking the flighttime of something like a powered sailplane. I also plan on using the two position switch F as a throttle cut switch, since this plan has no arming (I love how the FrSKY gives you throttle and switch position warnings on power-up though, nice safety feature!). My plan is to use that switch for throttle cut or arming, depending on what I'm flying.

If I rebuild my quad, I'd program that as a channel for the flight controller arming, since you definitely want arming and not throttle cut on a quad! The way that works with my Naze32 flight controller is when dis-armed, you can't spin up the motors. But if you dis-arm while the motors are spinning, they don't shut off until the throttle is lowered completely, at which point they cannot be turned back on until the arming switch is turned back on. Safety feature in case you accidentally hit the arming switch while flying, so your quad doesn't drop out of the sky.

Finally, I want to get my old JR XP5102 radio set up as a permanent buddy box to use with my Taranis. That was a 72 MHz radio converted to 2.4 GHz with the very old FrSKY DHT-U Tx module. Since I understand that is ACCST v1 only, and the computer is much, much less capable than my Taranis, I have no desire to use that as a Tx again. But mechanically it's fine, so may as well remove the DHT-U and keep it as a dedicated buddy box, as I have a lot of friends that will inevitably want to try flying my airplanes.

Binding the Lemon DSMP Tx module to the airplane was incredibly easy. Just programmed this model to have the internal RF off, external RF on and set to PPM mode. Powered up the plane, held the Tx module bind button while powering up the radio, and it bound a few seconds later. The button on the Tx module is also a range check if pressed when the module is already powered on instead of before power-on, though the "manual" for the Tx module doesn't cover hardly anything. I have yet to experiment with either the full range of the Tx module or the range with the range check activated.

All I have left to do is mechanically center the flight controls with the little U-joint pushrod bends, find battery position for proper CG, and wait for weather that allows me to fly this tiny plane outdoors on a maiden flight with rusty thumbs. Unfortunately the weather is not looking great this week. Guess I will have to build my Wombat (3D capable flat-foam scratchbuilt) and plan my next airplane purchase instead. I'm debating between either a larger (~60") powered airplane or a sailplane. Was thinking perhaps the Multiplex Heron.

I will update further once I've range and flight tested the Lemon Tx module. I can also share my setup for this Spektrum BNF plane if anyone is curious and/or wants to do something similar. Again the Lemon Tx module is lower power output than the FrSKY Tx, and presumable lower than Spektrum radios, so I'm not sure it's suitable for large outdoor airplanes, but that was never my intention. I'm only using it on these small airplanes with integrated Rx/ESC type modules, bigger airplanes with separate receivers will get FrSKY receivers.

Oh, one last thing I want to experiment with is seeing if I can get telemetry from this airplane on my radio, it's supposed to have at battery voltage on telemetry, but I'm not sure of the compatibility with that and the Lemon Tx module. I'll also update my findings with that once I know. The Lemon module says telemetry requires firmware from er9x.com. Not sure I want to flash er9x firmware instead of OpenTX, I don't really care for telemetry from this plane, but if I can get it to work with OpenTX that would be nice.

Overall my impressions with the radio are very positive, looking forward to getting more experience with it.

 

[Txmustangflyer]

He could pull the spektrum rx and put an SR10 pro in. The SR does the exact same thing as the spektrum safe system if its set to full stabilization. Or, the r 10 pro hooked to the safe system using sbus.
Thats how the wife's trainer is being set up. All servos go to the safe system, and from there, you can either direct line each channel on the safe box to the rx or sbus it. The spektrum rx doesn't have to be there.

 

[jseyfert3]

He could pull the spektrum rx and put an SR10 pro in. The SR does the exact same thing as the spektrum safe system if its set to full stabilization. Or, the r 10 pro hooked to the safe system using sbus.
Thats how the wife's trainer is being set up. All servos go to the safe system, and from there, you can either direct line each channel on the safe box to the rx or sbus it. The spektrum rx doesn't have to be there.

I don't think that would work for these indoor micro planes, like the Turbo Timber UMX my dad and I bought. The SR10 Pro (23 g) weighs more than the battery (17 g) for this plane! There is not a separate spectrum Rx, but rather one board that is the Rx and ESC all in one. The whole airplane only weighs 123 g. This micro airplane stuff is crazy to me, the 2200 mAh, 3S battery I use for my homebuilt quad (built in 2013) weighs 200 g, or 160% more than the entire Turbo TImber UMX plane...and the quad uses TWO of those batteries!

For any larger airplanes that use separate Rx/ESC and are large enough to handle the weight of a full-sized Rx then I agree the SR Rx is the way to go. I bought an SR8 Pro myself for a future larger plane, to give me more comfort margin while I learn to fly it.

 

[jseyfert3]

Update: I went to our club's last indoor flight of the season on Sunday. Did the maiden flight of my Turbo Timber UMX. The Taranis and Lemon TX module worked flawlessly. No issues there. I later went and flew the TT UMX at a local park, no further than 200-300 feet away probably. Again, no issues.

I've not yet looked to see if I can get any telemetry data with the Lemon TX module and OpenTX. That's on my to-do list still.

 

[jseyfert3]

Update on the Lemon Tx Module:

While it worked flawlessly with the Turbo Timber UMX, this past weekend I purchased a Mini Convergence VTOL. This also has a Spektrum Rx. I set up my Taranis, bound up the plane, and...nothing. It would not respond, nor arm. LED on the Rx indicated a bind though. I read the manual, did a lot of searching, don't know why it wasn't working. Did find one reference to the older gen 1 Spektrum radios not working with the Convergence, with one person listed the exact symptoms I did. That it bound to the radio but it did not respond to any commands.

I'm asking for help over on RC Groups in the thread about the Lemon Tx module. "It should work" is the answer. One guy has the same plane but has only flown it with a Spektrum radio, he's going to try it with OpenTx and the Lemon Tx module at some point when he has time.

I borrowed a Spektrum DX6e and the Mini Convergence worked just fine. No issues except pilot error, where I crashed on my first flight by stalling in a turn cause I slowed it down too much. Small, heavy (for it's size) flying wing. Needs speed...

I'm going to look at the Rx output on a scope hopefully later after work today, and see what the output is when bound to the Lemon Tx module and when bound to the Spektrum DX6e.

Oh, and if anyone does use this, it automatically scales signals to match Spektrum. So if a model with Spektrum says set limits to 100%, instead of scaling to 80% or so, you set the OpenTx to 100% and the Lemon scales it for you to the Spektrum definition of 100%.