Vibration analysis of the iFlight Nazgul 5 V2 and XL5 Frame. The antenna RUINED my tune! 

An extremely informative analysis with some very useful conclusions, many thanks for the effort!

Super interesting! I’ve always wondered about this. I used to only fly stubbies but got tired of the poor range. I’m pretty antenna mounting resonance is an issue on all of my quads currently. Thanks for all of the valuable info, you’re changing the game!

Thank you! :) I can't wait to try your tuning suggestions on my nazgul5!

Great informative video as always!

thanks. been waiting for this. just ordered a stubby for my nazgul. :D

Awesome, thanks. I flew this frame all last summer... It was one of my smoothes flying builds... I did only have a light weight flexible dipole on the antenna mount, and had soft mounted motors.. I will be building a fresh build on a new XL5 V4 frame very soon, I will deffo take your filter and antenna advice, thank you from North Wales.

Can't help myself laughing at how this quad swinging its antena. Especially at 220Hz. There's something naughty in it

Finally frame that i'm flying))) Thank you!

Awesome work Chris! 👍 Great to see this being raised, I’ve always found long unsupported antennas have affected flight performance, particularly when I used to use the original TBS Triumph antennas. If you model the antenna as part of the CAD assembly, it’s surprising just how much they affect the centre of mass position, even though they don’t weigh much, the resulting moment makes a huge difference to the CoM position (about 5mm in some cases) so it’s unsurprising that pitch and roll is affected so much!

I mount my MadMushrooms VAS antennas along with a thick bamboo stick for range purposes. I never thought that this could be the reason for not always having 100% clean video. Thanks for the great work. Cheers from Brasil.

@Crhis Rosser thank you for the work you put into these videos! Very interesting content that nobody else looks into! What are your views about the Hyperlite Freerane frame? Would you be willing to test that out as well?

Really amazing analysis and quite some insights into those Antennas from a very different perspective than just crash-resistance. However a stubby would also limit the signal strength, so this might lead to another whole level of discussions. Maybe - once you finish your tuning guides - tackling this issue of mounting the antennas best for vibrational stakes but also with the least possible loss in signal strength would be really beneficial. (You did this somewhat of that on your AOS5 build which is certainly a good start!) Maybe even partner with the guys from VAS to develop a rugged crash resistant non-vibrating antenna that still provides excellent 360° signal coverage? ;) Also... I'd love to see a vid of how you do your test flights to get these histogram-results. Somehow my tinyhawk freestyle looks quite clean in the histogramm but in the waveform you can see a lot of gyro-noise which also triggers D-Term quite heavily... and it's quite hard find the root cause (this little thing with it's thin base plate may just in general have its limits though *G*). So I wonder if I just don't test-fly correctly and comparably enough to see it in the histogram.

First of all i wanna say thank you 4 the nice content u are steadily dropping, awesome work. 👍 I would be interested to know which software u are using 4 your resonance/vibration analysis and where u become those nice dummy models u work with. I know it goes very deep but, I would appreciate it if u may can make one or two extra videos how setting up and analyse this kind of modell. Best regards.

Really love your content and analyses! Thanks! Do you think the 58hz bump in this is related to P or D oscillations from either high gains or too much filter delay?

Wow great timing!! I got this quad a few weeks ago.I was just thinking about getting a bigger antenna. With the battery on top and a gopro it has some bad signal blackouts. I do not see how a stubby antenna could even be flyable for me on this quad. Great video!

Very interesting, thank you !

That flopping antenna is so funny 😂😂

Thanks Chris, really insightful. Data driven decisions, you are paving the way. Dreaming of the day when you and uavtech collaborate, we may get unicorn quads... Prepare for 'do mines next, please!' ...2fiddy, please....

Hey Chris. Thank you for doing this analysis. I've been flying the xl5 for around 6 months now and to hear that it performes good in the vibe analysis is nice. However i've realy come to love the TPU print that holds both the sma Connector and the xt60 in place which you said was very suboptimal. Is there a way of redesigning the TPU part (Moving it closer to the frame or printing at a higher infill) that could make it vibrate less? I would realy hate having to mount my antenna and xt60 differently since thes tpu part is so practical. Also, frames like the Qav-s JB ed. have tpu sma mounts which go out the back. Are those suboptimal aswell?

Thanks, reealy good and educational. I would be very interested in how you set up the simulation model. I mean material properties, motor modulation, like bell weight rpm, antenna material stiffness etc.

This is the first video of yours I've seen where the comments section has multiple people asking if this antenna issue really matters or is worth worrying about. Knowing this isn't a general review video but a vibrational analysis video. I wonder if this is a demographic change because it's a BNF so maybe newer users or maybe something else. This isn't too say I disagree with them. An antenna above the battery is a night and day difference for rf on 5.8. I did notice most of the people who did question the antenna issue mentioned theoretical comparisons and general user interactions, like the things you might see in videos, instead of personal experiences. Great job as always. You're really dialing in the entire vibration analysis process. There's much less repeated material so it feels more streamlined and there's more actionable advice. Thanks again.

I fly the Cidora SL5 V2.1 frame, i hope that the things you said work for this frame too, its basically the same frame with slightly shorter arms 217 vs 227mm I am ordering some stubby antennas for my cidora sl5 ASAP, thanks Chris, this is excellent work.

Thank you man!

Hi Chris, great and informative Video as always. How much does the flexibility of the antenna itself cause the 90hz Mode compared to the flexibility of the TPU? I am trying to figure out if a stiffer mount with a still flexible antenna is a good compromise between reception and resonance performance.

Good job Chris:-)

I’ve been waiting all week for this video, thanks Chris. Strange that I didn’t have those antenna frequencies on my stock Nazgul, makes me wonder if those logs had something else going on, maybe a loose or broken antenna?

Hello. What an amazing video. When I start the tuning on my Xl5 should i mount the Hero 10 and then begin or without it? And then tune the quad with GoPro on different profile and switch back the profiles? Thank you

I have been telling people that some antennas act like big maracas. Glad you did this video.

I recently got the iFlight Chimera7 frame and it has a lot less vibration than others I've tried. But when I added the tpu gopro mount I got two low resonances like shown here with the antenna. I made a DIY metal bracket which got rid of them. I've seen antennas cause vibrations in the bb before, especially the long ones like the Albatross. A stubby mounted under the fpv camera might have better range, as it would be clear of the lipo and gopro. You'd have to be prepared to replace it in crashes, or protect it somehow.

Thank you 🙏🏻👍🏻

Great video! Super helpful... may have to watch about 23x more tho haha... what do you suggest for a nazgul5 v2 6s w/ tracer? Stubby?

This is the same on the non hd versions too. I put 2 zip ties through the tpu mount to stiffen it up against the standoffs. Lowest modes are gone and LP take care of the rest! thanks for the watch out

I use the Caddx Rush Cherry 🍒 antenna now after the iflight SMA to MMCX broke just moving the top plate. The Cherry antenna has a short tube and the screw spacing is the same on the plastic bracket to TPU mount. So you can have the tube in all the way to make a stubby or out an inch for longer range if if you want. I used some extra screws from the box and the clear plastic nuts that are used on the stack. I put a small amount of UV glue on the nut so it can’t back off. It seems to work well I’ve been out 800 meters easy. It will go much farther I’m sure.

Thanks for the analysis, Chris. I have the analogue version of the v2. I was very surprised by how much the antenna and mount contributed to the resonance! Apart from moving over to a stubby, what else would you suggest? Get rid of that TPU mounting completely? Strap the stubby (or a longer antenna) to a rear standoff?

Hello Chris, thank you for all this amazing work. Do you think it is safe for me to turn off gyro low pass filter 1 and 2 with this frame and do a test hover? (bf 4.4)

Dear Chris, thanks for your very useful analysis. I had problems of this kind with a TPU mount for my Source One build. But I don't like stubbys in terms of video performance, when the quad is flying in my direction there is a (someties significant) lower reception. So what if I print the antenna mount with PETG instead? It's not as flexible as TPU, maybe the resonance will be shifted in a higher frequency range where filtering work better to eliminate it ...

weirdly, i was just troubleshooting my quads,had some weird jello and twitching when i mounted longer dji antenna and immortal T vertically just behind the hero 6. i added some cable ties plus an embarrassing amount of hot glue to the dji antenna and a huge amount of hot glue to my immortal T's base, it helped quite a bit. on the dji i added two cable ties rising up to form a sort of curving triangle reaching up about halfway on the antenna stem, then addeda piece of cable tie between the triangle legs and covered it with hot glue too. i dont do black box, but i've always been concerned by antennae vibrations, its nice to see my instincts that these could be critical to performance, being proved true.

I wonder if a more robust antenna mount would get rid of the issue? The reason i thought of this is because Joshua Bardwell uses that type of antenna on his new perfect freestyle build and doesnt have this issue. But his vtx antenna mounting locks in with his reciever antenna mount and im thinking it makes the mount more rigid getting rid of this issue.

Thanks for the insight. I'm thinking making the antenna/mount stiffer will likely just move the frequency vibrations lower. Making it vibrate more would bring it higher and more able to be filtered I presume. Interesting situation to think about.

Great video. Could you recommend a couple stubby's. Thanks again.

Hi Chris, my quad has the iFlight Cidora SL5 frame, which I'd expect work have very similar vibrational modes to the XL5 frame, so I'm paying a bit more attention to this video in particular, haha. Plus your advice about the VTX antenna is pretty universal, regardless of frame. Quick question about that though; I've been mixing/matching parts on my quad for the past year or so now, and I'm currently running a Lumenier AXII 2, which while being ~2.5" long is rather stiff. Would you expect antenna stiffness to raise those low-frequency modes very much? I have the exact same TPU antenna mount as the Nazgul, so that might be erasing any improvements I'd get from the stiffer antenna. A sensitivity analysis of antenna stiffness for a given length would be interesting, since we're probably not all gonna switch to stubbies after watching your video, lol. Thanks for the awesome vibration analysis!

Amazing! Now, how about the Yaw LPF? Should we also disable it since the Yaw seems to be clean of resonance? Thank you!

Have you done any vibration and resonance analysis on a 3" (any)? I wonder if/how the frame size affects vibration and resonance.

I would love to see this done on a micro, something that Nick Burns would fly. I assume a lot more movement and flex on a ducted 65mm, 75mm or 85mm quad, but it would be interesting. Another suggestion would be a Flywoo explorer, to see what a lightweight deadcat does? Either way keep it up interesting stuff.

So all those fancy long range quads that supposedly could freestyle are prone to more prop wash given their extra long antennas? Also what would be the impact of shorter arms (3.5-4j’’) and smaller motors on a frame resonance? I would guess less material in the frame and less power from the motors and likely more noisy motors would give more or less the same picture as for a 5’’? Thank you Chris! Good to see some simulations!

I don't have the HD version but an analog Nazgul5 and I immediately found the flimsy antenna mount suspicious when I saw it. However, flying on analog a stubby just wasn't an option because the range really suffers. I 3D printed a big antenna and GPS mount from relatively stiff TPU and I hope this will give me more headroom for tuning. I was surprised seeing the vibrations being more pronounced as on roll on a true X frame. I think this will be even more so on wide X frames (have to check again on your Source One analysis).

Awesome. Been flying my nazgul… with a stubby for months already. Because it crashes better that way. ;) … I’ll try your filter recommendations. Thanks a lot!

In my experience stubby antennas struggle when the battery and a GoPro are blocking the signal. Like many things in the hobby, there's give and take.

I know you have done the QAV-S JB but would it be possible to compare it to the Johnny version? It has the metal camera protection and is a tad taller

I alreadt have both, like them alot, but i will defently look at mynantenna mounting

Pulled out my Nazgul 5 and looked at the stock antenna, and easily can see that the TPU mount is overly flexible beyond the frame. With the DJI antenna it seems like the holes for the other antenna options are just weakening the amount of material there (and flexible TPU isn't helping much in general). Perhaps if removing those holes and increasing the material may help strengthen that a bit.

What software are you using to vibration analysis and simulation? Thank you

Can we have a suggestion about the Micro Apex 4 inch Frame? What happens with the frame resonanse when it scales down compared to the regular Apex frame.

Hey Chris, just one question what if I am not doing freestyle with the quad but some occasional cinematic with this bnf? does using a long antenna matters? because I am flying maybe 1 km away i am worry that if I use a short antenna it will get blocked by the battery and gopro and lose signal

Will you be doing this a noise test on a source one v3 in the future?

Really amazing analysis Chris! I am a structural civil engineer and many times I wondered why there was not much talk about resonance and the vibration modes of the frame versus the performance in flight. Have you modeled the effect of the stack's support configuration on the amplitude of the noise? a while ago I had a serious problem with noise in the yaw axis and finally I realized that it was caused by very flexible supports, and it was made worse by the capacitor that unbalanced the center of gravity of the stack + capacitor assembly. It would be interesting if you could address that topic in a future video.

I always hated antennas sticking out for no reason, now i have a reason :)

Hi appreciate your help can you do testing on iflight dc5 4S

Please do an analysis of the Rekon 3

Considered an analysis of the TBS Aureo? Would your models work on something that's not 100% carbon?

I had a similar problem in my apex with 2 DJI air unit antennas floating free and bouncing. I did a cross union with 2 zip ties, problems gone. It was clearly visible in logs at very low frequency with strange behaviour during the flight and propwash management.

Hi Chris, what would then be at least the best compromise how a sticking out antenna would provide least amount of noise into the system? Because for example for a long range copter there is no way to go with a stubby.

Hello! Thank you for your hard work! Could you please tell me, in betaflight configurator 10.8.0, In "D term Lowpass Filters" I should disable dynamic filters and enable only D Term Lowpass 1 Cutoff frequency 100hz at BIQUAD filter type? Or how should it look like?? Thank you!!

Hope you can do Analysis too for the Catalyst Machine Works 5" BangGod.

Can you please test a TPU DJI antenna mount? More stiff but must add bounce still.

Excellent video. One question that may sound a bit exaggerated but still bothers me: If we could have Gyros down under the motors and read the data simultaneously, could this also improve the PID corrections? I mean in all of your videos the way the motor's bases bend seem to be a big issue.

Would be interesting to have a camera aimed at the antenna and see the oscillations during flight

I have this quad in analog version. Would that be helpful to support the antena by stiffening it with carbon rod shrink-wrapped to it or using a carbon tube perhaps?

Interesting...I just mounted my Vista antenna this way and developed a new vibration in my quad, didn't associate the two at all. I'll go back to my old mounting method (zip tied) and see if it improves. Also interested in an analysis of the 4" Micro Apex...happen to have one ordered!

Would it be as similar in terms a of resonanve for an Iflight SL5 frame (Iflight cidora) ? And are you using Solidworks Static for frequency simulations ?

Man this guy just came out of nowhere☺️

Ok you might have a valid point, but the whole reason they have a flexible mounting of the antenna is in case of a crash, having it like this will not snap your antenna, breaking off. And of course you come with a valid solution, however the frame/drone you are referring to is a budget drone and not meant as top of the line. So I personally understand their design choices and agree with it for the price point.

Also the XT60 connection should be taken into consideration as a vibration factor.

I have not gotten into tuning yet but I still watch your videos. Yesterday I noticed my Gopro video gets blurry at certain throttle ranges on my Gep mk4. That's got to be caused by the things you talk about here. Harmonic resonance from the motors and frame matching up with my gopro mount, right? I'm going to have to learn about filters and stuff.

Could you do an analisys of Flywoo explorer? there are a lot of people that fly with that kind of frame

What about Crossfire antenna zip tied to the motor arm? This is a common method of mounting the receiver antenna, but I now wonder what that's doing to vibrations.

I have a question about these simulations - how is the material stiffness determined for each part? Does the antenna have a preprogrammed different stiffness compared the the carbon fiber frame? Just curious because I feel like relatively accurate values of stiffness would be necessary to accurately predict the real frequency of these harmonic modes (and make the filter recommendations relevant), especially for those lower frequency resonances and for builds with parts that are potentially orders of magnitude less stiff than other components (such as the frame vs the antenna). It would be cool to see how many different stiffness coefficients/what parts are different stiffness for these simulations.

Hey Chris. huge fan here! For Nazgul..can I replace the antennas with a spare DJI goggle antenna?

hii i got hot motor 1207 2.5" what should i change?

I'm looking for a similar video for the iFlight DC5 Titan 1.4

Hi Chris, if vertical lines are frame resonance, then what horisontals are? Mark has mentioned this but not clear enough

Can you do a review on pyrodrone hyperlite freeranger pls

Thank you for doing an analysis on the Nazgul, as it's a very popular BNF and I happen to own one myself (along with... uh... three other iFlight BNF models)! However I'm going to play devil's advocate here - because you know someone is going to ask this question, and I hope to do so more politely - wouldn't an RF engineer doing their own analysis focused on solely *that* area probably say "the most important thing you should take away from this video is that you should mount your antenna as far away from the carbon fiber body, the electronics stack, and the battery as possible, and find the longest antenna you possibly can!"? Like, what's more important - tuning the frame for the least possible vibration (which can be compensated for, at least to some degree) or not falling out of the sky when you're flying at range? :) I imagine that every design is a tradeoff in some way, right? Also, for what it's worth, I will say that out-of-the-box the iFlight quads I own absolutely had the best tunes - by far - of any manufacturer.

Thanks for this analysis of the Nazgul frame. I've been battling noise for months on my Nazgul5, I never considered that my Caddx antenna might be adding noise into the system. Recently I've been having an enormous amount of noise on my yaw axis which I am still trying to work out. I swapped out my XING 2208 1800kV which were dinged up a bit with a set of XING2 2207 1855kV. It helped a bit but I still has an excessive amount of broad noise on the yaw axis. Now I am suspecting my particularly soft TPU mount may have have some part in the excessive noise. Can you by chance share the XL5 frame model that iFlight sent you? It would be extremely helpful for creating a better antenna mount and also running my own simulations on the frame with different antenna mounts. I would definitely become a patreon if you would be willing to share the model 😁 thanks for this video in either case!

So if I replace that long antenna with a stubby, do I need to also change the mounting method? or would the default flexy tpu mount work fine with a stubby?

I took a look at some of my old scaled gyro logs from my stock Nazgul 5HD 6S. They are extremely clean and I'm not seeing any spikes above about 40Hz or below about 200 Hz on Pitch, Roll, or Yaw. Maybe I just wasn't flying aggressive enough back then to bring them out. It makes me wonder how do we know there just isn't something off with this guys set up or tune?

im not educated, but my personal experience with the nazgul is the after a few flight the antenna get a lil wiggly, not a big deal to me as i just know i should snug it when i change baytery packs

Thanks for the analysis! I am not sure how to word this and by no means do I want to be offensive. I am just trying to understand more. I am curious what your answer would be if someone asked you if these issues you address really matter? "Like come on, the antenna cant really effect the flight that much... my Nazgul is amazing with the stock antenna mount". Tons of people duct tape quads together and they fly "perfectly" for the user. I understand you are really diving into the details and I love it, but from a relative flight perspective I would love to hear your thoughts on what actually matters in a real world instance. Most FPV drones are not flawless flying machines, plus the second you crash once, all these calculations could be completely changed right? Sorry for the long comment. I guess I could sum it up with, Go fly a BNF Nazgul and then change the antenna to a stubby and prove to me there is a big enough difference worth the stubby price and potential lack of range (if thats a thing, im not a genius in FPV).

Edit: Sorry that my comment is so similar to others. I didn't read down before I made it. Hey Chris interesting stuff. I understand what you're saying about the antenna mount, but mounting the antenna on an arm really seems to limit its RF performance due to the shadows created by the frame itself as well as the battery. What if the material used for the rear antenna mount was PETG which is much stiffer than TPU? Would that push the resonance of the antenna higher, out of the range of prop wash and other similar disturbances that we want the gyro to deal with? Also when you say "stubby" are you talking about an antenna without any tube at all? How long can it be before it starts creating problems.

Wow, I just had a HUGE problem with a Rekon7 and and HRB 3300 6s. I couldnt strap it down with a rear second strap or it was d term hell and HOT motors within 10 seconds. The rear of the battery contacts the antenna(about 8" long stalks) TPu mounts and probably is coupling antenna modal vibrations into the frame via the battery!

I have both frames xl5 and xl7, some time ago I installed tpu antenna mount and both drones start flying worst, now I know why

can you mix actual real life slow mo video of the antenna vibrating. Or any other parts. Some video will be hard to record and amplitude really small but I am sure there could be a way to do it. Like stroboscope light on reflective tape.

Do you have any recommendations for antenna solutions on a long range quad to that minimise resonance?

Same probably goes for the huge battery wires and connectors that people allow to flap around in the breeze.

Yeah my long range rigs the antenna def vibrates.

wish there was a roma f5 v2 dji,review,tune,like this.

Hi Chris! Just curious as to the real significance of the mass participation factor of a small antenna relative to the mass of the rest of the build? I've been doing my own frequency analysis on my own designs on SolidWorks as well and I don't really see a practical difference between a 3g antenna (with a light hanging off the back in the context of a 250g build. When using such a light antenna, is it reasonable to say it is worth the extra resonance participate for better VTX signal?

Please look at the popular 4inch long range quads. They all have long mount antenna and I think they all mount via TPU. For example, look at the iFlight Chimera 4. If one changes the antenna mount as you recommend, how does this affect range? I think the topic of long-mount-antenna needs a more nuanced discussion.

for those who have the 150mm long range antennas is there any good ideas besides a solid pla mount?

thanks, so how and where to replace/move this antenna ?