I recently got a Diatone Roma F5 so I finally have a kwad that can carry an HD camera without issues. I prefer to build my kwads myself but the bind-and-fly builds are simply a lot cheaper! While considering the iFlight Nazgul and Cidora I stumbled upon this new kwad from Diatone and immediately fell in love for a few reasons:

• Well designed freestyle frame with adequate space.
  
• Moulded plastic parts instead of 3D printed stuff that falls apart easily.
  
• The side guards look unusual but interesting since my other kwads collect too much grass between the stack.
  
• It has a great F7 controller (with onboard WiFi!) and a powerful BLHeli_32 ESC.
  
• It's super affordable and all parts are readily available.
  

The only thing I didn't like was the HD camera mount, I would have preferred something where the usual fixed angle TPU holders would fit. It was also unclear if the motors are any good and if it's going to be just as popular as the iFlight kwads, but I went for it anyway.

When the kwad arrived I was amazed by the build quality. There's a lot of attention to detail in the frame and all carbon parts have beveled edges. The plastic parts are as good as they look and even the screws are gorgeous. The motors look strong, have smooth bearings and no play that could cause vibrations. Everything was assembled nicely and the soldering is absolutely top notch! You also get lots of spare screws in the box, and black plastic parts in case you don't like the white. The only thing missing is extra M3 nuts (and guess who lost one of them after the first flight).

The FC's gyro is protected by a little aluminium "box" which I guess helps to keep electrical noise out. When soldering my receiver to the FC I noticed that the ground pad required more heat than usual to melt the solder, so I think there's a massive ground layer in the PCB. I like that it has a USB C port, that'll last a lot longer than those flimsy Micro USB ports. The ESC doesn't look special, but it has a decent amount of ceramic capacitors which is important. There's also a 470 µF 35 V Nichicon cap to absorb voltage spikes.

The Diatone branded Runcam Phoenix2 has a nice image, very comparable to the Caddx Ratel I had before. Lately I'm on a hunt for lower latency though so I'm replacing the cam with a Foxeer T-Rex soon, very curious about the difference it would make. The VTX is nice, 400 mW is plenty in most cases. It has a bunch of leds to clearly indicate the band, channel and power. I just wish it had a microphone, and it doesn't look like you can add one.

The Roma came with Betaflight 4.1.6 but it wasn't configured very well. I upgraded to the latest 4.2 version and improved lots of settings:

• Changed the PID loop from 4 kHz to 8 kHz, the F7 can handle it. EDIT: better leave it at 4 kHz, see #15
  
• Airmode was configured to be on a switch, changed it to permanently enabled.
  
• RPM filtering with Bidirectional DSHOT was not set up. Enabled it. See https://oscarliang.com/rpm-filter/
  
• Motor idle was at the default 5.5%, changed it to 4% but 3% might even be enough. I also set Dynamic Idle to 15 (1500 RPM).
  
• Filtering was very conservative, almost default. After testing I settled on a Gyro filter slider of 2.0 and a D Term filter slider of 1.8. Motors never got hot.
  
• Also optimized the dynamic notch filtering with the often recommended 0 percent, 250 Q and 90-350 Hz range.
  
• PIDs were close to the defaults as well, just slightly higher P values. Starting my tuning from the defaults it turned out that there was a bit too much damping from the D term, so the PD balance chosen by Diatone was probably pretty correct.
  
• I settled on the PD balance slider at 0.9, PD gain slider at 1.2 and Stick response (feedforward) slider at 1.5.
  
• Other finetuning settings like I-Term Relax Cutoff were slightly changed, weird? I went back to the defaults.
  
• Last but not least the VTX power level settings were wrong. Deleted 100 and 600 mW options so only the correct 25, 200 and 400 values are left.
  

I also changed to props-out configuration because I'd rather see grass on the stack side guards than on the lens or all over the VTX in the back. After some maintenance yesterday I did make the rookie mistake to put the props back on in the normal direction, so I got a scary loud surprise when trying to blast off for a test flight... Now I'm going to put some arrow stickers on the arms to keep me from making the same dangerous mistake again.

Another (harmless) mistake I made was to set up vbat_sag_compensation. This was a great option for my 3" Armattan Gecko because the last 20% of the throttle didn't add much thrust and only wasted battery power. Now for this Roma with the lowish 1700 KV motors this removed the best part of the throttle range. So for the maiden flight I wasn't all that impressed with the power because vbat_sag_compensation was more like fake_sag_allthetime   

Because of this and because of winter weather I don't have any great flight footage yet. I'll post something that does the Roma right once the winter weather is on the way out

Here's Albert Kim's review:



Joshua Bardwell's detailed setup guide:



And Bubby's chill flight:

Here's a backup of the original Betaflight configuration. Keep in mind there's a lot of room for improvement...

Since I don't have a 3D printer I had to get pretty creative to mount my HD cam

Great review, I'll deffo consider this for my next quad purchase

(19-Jan-2021, 08:22 PM)TrikeTrash Wrote: Do watch the little white thingy that holds the battery leads close to the quad.  It has a tendency to get loose and allows the prop to start nipping at the wire - not kewl.  

Thanks for the heads-up! With getting loose, do you mean it doesn't stay in place? Because I noted that it's supposed to be held up in place by the side guard. Or do you mean it easily breaks? In that case I would reinforce it by putting a zip tie around together with superglue.

(20-Jan-2021, 02:12 AM)TrikeTrash Wrote: Would like to hear your thoughts on the mamba VTX...  Seems to me the listed power levels are way off, or maybe I just have a bad one.  I did a side by side walk-a-round of a metal building; an ET125 Whoop at 200mW vs the Roma at 400mW and the whoop ate the Roma's lunch. I have a Mach 3 from Raceday that I'll be replacing soon - we'll see how that works out.

Another thing that is way out there... Since the quad's arms are replaceable I would love to have a new set of arms that are 2.5 inches longer (one prop radius) than the current ones. The reason being, is that if the full 360 degree prop arc is clean of the quad the noise goes down significantly. Plus I could play around with larger props.

I don't have any issues with the VTX, seems to work very well, good range and no weird interference or lines. Just make sure you edit the Betaflight config like I described, and double check the power level with the LEDs. Also make sure you screw down the antenna tightly, Joshua Bardwell mentions this in his video.

Regarding the arms - maybe some other Diatone frames like the GTM or GTT have compatible longer arms? If not you're free to create a FrankenRoma   -> https://intofpv.com/t-phantom-x-my-first-build

400wm is ok.. is not the end of the world.

I have this quad, and I really like it. One comment on OP's tweaks to the settings: "Changed the PID loop from 4 kHz to 8 kHz, the F7 can handle it."

I tried this and found two bad effects. (1) I could no longer connect to the board's wifi with the SpeedyBee app, and (2) My OSD warned the temperature was getting high while the quad was sitting on the bench; seemed real, I could feel it. Both went away when I changed the PID loop back to 4kHz.

I'm interested in trying some of the other suggestions too, but I was wary of getting them wrong because I haven't used Betaflight much before. Would you be up for posting your custom config diff or screenshots?

its normal that the chip heads up more on 8k, its not made to sit on the ground. the wifi issue is strange, seems your cpu is to high. you can check your cpu usage with "tasks" in the cli.

Hi comster! Actually I think you're right, it's better to stay at 4 kHz. I often read that an F7 can handle 8 kHz but after checking the tasks command it seems that the CPU is right at the edge of being overloaded.

I honestly don't get why 8 kHz would be better than 4 anyway, the highest vibration frequencies a kwad has to deal with are around 1 kHz, and motors can't give any meaningful reaction to it that fast.

So I actually went back to 4 kHz a few days ago. The weather has been nice lately so I've also been able to do more testing and PID tuning, I'll post my findings and some config lines soon.

I bought myself one of these a couple of weeks ago and I'm having a lot of fun! I'm running an Insta360 GO so the quad feels very nimble 

BAM! The video you've all been waiting for!   

Regarding the Betaflight configuration I spent quite some time trying to find the best settings;

As noted by comster, running the F7 cpu at 8 kHz doesn't seem like a good idea (if you have RPM filtering enabled, which you really really should: https://oscarliang.com/rpm-filter/)

I'm not sure if it's a good idea to use Dynamic Idle. If you set it too low the motors will have a hard time spinning up again from low RPM. There are some improvements coming in BF 4.3 though. If unsure, don't enable dynamic idle and leave motor idle at 5.5%

I see quite a lot of vibrations in my gyros, especially with the motors running around 33% throttle. In my video you can hear a lot of motor whining in the end, at a frequency around 200 Hz. I probably overtuned everything, so I'm going back to more conservative filter sliders at 1.5. Together with the RPM filter, it's still way better than the default Diatone filtering.

With D-Min disabled, a PD Balance of 0.9 seems perfect. With D-Min enabled, a PD Balance of 1.0 seems best. The PD Gain can be pushed higher than 1.2, but 1.5 results in too much oscillations. I think I'll keep it at 1.4. Since I'm using an R9M radio link with ExpressLRS I can get away with FeedForward up to 1.8. For radio links with more jitter I don't think you should go higher than 1.2.


A few other tidbits:

While the camera and VTX are not bad at all, I noticed some diagonal interference lines once I got my new high resolution Sky04X goggles. I've replaced them with a T-Rex and Rush Tank Mini and get a fantastic low-latency analog image now.

After a little crash the HD camera holder pivoted forward and my battery got pushed up against the sharp edge on the bottom of the cam holder. It almost killed the battery so to prevent this I chamfered that pointy edge with a file. This does't take away its strength at all, there's too much material there actually.

The battery leads holder on the side has held up fine, but just like TrikeTrash warned I still got some cuts in my wires, probably when the prop of motor 1 bent upwards. I just put some electrical tape around it now but I'm looking for ideas to fix it permanently. I'm not sure if you could run the battery leads to the back neatly, it's pretty crowded with the antenna connectors, and I'm worried the high currents through the wires would cause interference in the receiver and VTX?

Just like JB mentions in his review I found the kwad flies a bit dull with the provided S5 props. I tried Gemfan 51433 props, which are better, and 51477 props, resulting in the powerful beast you see in my video. For the lulz I also tried the fancy Ethix P3 props but they are not a good match for the low KV motors. Got some Gemfan 51466 on the way also which I hope to be the perfect balance between agility and power. It's all pretty personal, because I saw another review video of someone with a calm flying style who loved how the S5 props are easy on the batteries. If you tried any other props on this kwad, I'd love to hear how you experience them.