I figured I would post this story and video to remind others of the importance of antenna orientation and not to make the same mistake I did last weekend.

Since I got labelled an outcast at my local park, I've been doing most of my flying at another location which is among some fairly isolated fields. Apart from the odd dog walker once in a blue moon, I pretty much have the whole place to myself whenever I go there with no bother from anyone. 9 times out of 10 I never see another soul there and it's a really tranquil setting during sunrise or at dusk...until I turn up with my noisy quad that is 

The biggest risk with this location are the huge fields of scraggle which is up to my chest, so this is a model flyers nightmare. Until recently I've been avoiding flying over the middle of the fields as much as I can for fear of my quad coming down in the scraggle never to be found again, so I've been mostly flying around the edges of the fields where a wide(ish) strip has been cut back to ground level.

All in all, I must have flown in excess of 80 packs at this location, and during my last few visits I started to get a bit braver by flying further into the fields and across the tree tops and over the adjoining fields to try and make things a bit more interesting.

Last Saturday, my worst fear became reality. As I flew across the treeline and over the top of one of the adjacent fields, with around 56% RSSI I experienced a sudden total RXLOSS event followed almost immediately by a failsafe. All I could do was to watch through my goggles as my quad nose-dived out of control into the sea of scraggle below. The quad was only about 150m away from me with a single tree between me and the quad when this happened.

Panic set in as I quickly tried to make my way across to the next field while praying that my radio would get an RX connection back and that my buzzer would actually work. It was a huge relief when I heard the faint sound of my beeper coming from somewhere deep into the scraggle although it wasn't much fun trying to wade though it chest deep, but I eventually got to the location of the beeping and managed to find my quad buried in amongst the weeds at the bottom. Without a working buzzer there is no way I would ever have found it, and it would definitely have been lost forever. So it looks like I received a get out of jail free card on this occasion.



I was glad to see that my quad was still intact with the battery and HD cam still attached, although the stack had suffered a bit of collateral damage but it was just a couple of broken stand-offs. This is the only good thing about crashing into that stuff as it provides quite a cushioned landing. With a broken stack there was no more flying so I packed up and went home trying to rack my brains as to why I'd experienced my second ever RXLOSS almost a whole year after the previous one with exactly the same equipment that I'd since done hundreds of flights on without any issues whatsoever, and to try and understand why it suddenly just failsafed out of the blue having done more than 80 flights at that same location without any problems until now. And coincidentally, the RXLOSS I suffered last year was in the same area, just one field away.

I really hate these type of unexplained events, and blackbox data unfortunately revealed nothing of any value, so it appeared to be a complete mystery which doesn't do much to inspire confidence in the equipment and electronics. I fixed the broken standoffs on my quad, gave it a good spring clean of any dried on crud while the boards were out, and did a thorough inspection for any bad / broken solder connections or foreign objects on the circuit boards (there were none). I then hung my quad back on the wall in frustration not knowing the cause of the problem.

It was only after reading a post by Krohsis earlier this week in another thread to do with antennas that the penny actually dropped. Due to the orientation of my body and the angle that I usually position the transmitter antenna at (roughly pointing at a 45 degree angle out to the left of the transmitter), after re-reviewing the video footage I realised there was a high probability that my quad had entered a null data transmission zone just long enough to cause a total connection loss and the subsequent failsafe.

The video at the bottom of this post shows the story along with the moment when I thought I might have actually lost my only flyable quad.

For almost all other flights at this location I've been standing in a particular spot facing a particular direction while flying the quad out to the front and mostly to the right of me, so with the tip of the antenna pointing 45 degrees outwards to the front left, that was no problem. During my last two sessions at this location I moved to a different part of the field and was facing a different direction which meant that I was then also flying out to the left of myself...which is the exact direction that the tip of my antenna was pointing. I guess for the previous packs I flew from the same position I just got lucky in that I didn't enter the actual null zone of my antenna, or at least not for long enough to cause a total connection loss.

I haven't flown my quad since, but having a reasonably viable explanation as to the cause of the RXLOSS and failsafe, at least I can go back to that location and still have some confidence in my equipment knowing that it was most likely just down to pilot error.

I guess the moral of the story is never get complacent with your equipment and always remember to check everything before you take off including the direction you are facing and the orientation that your transmitter antenna is pointing. I just went into autopilot mode and put the antenna in the same position that I previously did without even thinking. In fact, that position which I had been using was a disaster waiting to happen and I don't know why I ever thought that was a good position to put it in. I guess sometimes you just get lucky but then your luck eventually runs out.

I've since discovered that the best positions for a transmitter with a single whip antenna is either straight up so the tip points at your head (meaning the null spots are towards the ground and also directly above your head slightly to the rear which is an area you are unlikely rarely fly in for long enough), or at 90 degrees directly out to the left or right so the null spots on either end of the antenna are to either side of you at ground level (again, areas you are unlikely to fly in for long enough). It's a shame the Taranis doesn't have diversity antennas like some of the Spektrums do whereby one antenna is positioned horizontally (in the handle) and the other is positioned vertically (out of the top) which then gives signal coverage from every angle with no null spots.

I think I will now also seriously consider investing in a GPS module that could help to save my quad in future in the event of a buzzer failure, or if the RX connection fails to recover itself due to wiring or component damage, because even a self-powered buzzer is useless in that scenario where the LiPo hasn't actually become disconnected.

I might also think about moving to the 900MHz transmission system for some extra security/reliability and peace of mind.

The pictures below show the poor choice of antenna orientation I was using. I recommend that no-one orientates their antennas like this unless they have a very good reason to do so.

 

Flight footage of the crash and the aftermath...

Well at least you found your quad.  I didn't know what scraggle was before now, but it looks like a joy to walk through....   Was the scraggle dry enough to catch fire, or is it just too wet there for that in your area?

What I can say is, WOW what an area to fly!  And you could fly for miles and miles and miles....to quote The Who.  You should take up long range....I can see some serious distance being racked up with a wing or a big quad.  

Also, you don't look anything like I had you pictured....   And good flying too!

Never go out without your beeper kids...words to live by.

(22-Sep-2019, 12:22 AM)Krohsis Wrote: Well at least you found your quad.  I didn't know what scraggle was before now, but it looks like a joy to walk through....   Was the scraggle dry enough to catch fire, or is it just too wet there for that in your area?

What I can say is, WOW what an area to fly!  And you could fly for miles and miles and miles....to quote The Who.  You should take up long range....I can see some serious distance being racked up with a wing or a big quad.  

Also, you don't look anything like I had you pictured....   And good flying too!

Yes, the definition of scraggle is HERE for others who may not know  

You must have really good eyesight to see what I look like in that fly-past  

As for long range, I just don't have the bottle or nervous disposition for it. It was bad enough my quad going down just 150 metres away from me. All of that lovely green surrounding area you can see for miles into the distance is privately owned farmland, so if my quad was to go down at all into any of that land then I'm not getting it back, regardless of GPS or any other tracking technology. When Mr farmer with his shotgun tells you to get off his land then you do as he says.

The problem with this location that I'm currently using to fly at is that it's actually private land owned by a housing development company. So officially I'm trespassing, but I figure that until they start bringing in the bulldozers, they probably don't really care that I'm there because I'm not causing any harm. However, it's probably one of the reasons for the new fences around the perimeter going up that you can see in the flight footage, to try and stop dog walkers and people like me getting into those fields.

And because we have too many people in the UK, the government and local councils seem to think that destroying all the beautiful green belt areas to make way for new housing is the answer, with the farmers happily obliging when they get offered millions of pounds for their land. But that's another whole topic of discussion so I'll try not to rant about that here for now. It does sadly mean that in a few years time all those lovely fields will be transformed into an eyesore of a housing estate as per the plans below.

(22-Sep-2019, 01:41 AM)Sugs Wrote: Never go out without your beeper kids...words to live by.

Yes, I don't really get how some people don't bother with a buzzer just to save a few grams of weight.  I actually have two on mine (a normal buzzer wired in parallel with a ViFly buzzer) and even then I was only just able to hear the beeping of two buzzers from deep in the scraggle.

Ross (Coppertop FPV) was unfortunate enough to lose his newly built 8" on it's maiden flight a few days ago for that very reason as documented in the video below. He also has some good advice on setting up GPS logging on the Taranis for those who haven't done that or don't know how (just watch the video to find out)...

(22-Sep-2019, 02:10 AM)SnowLeopardFPV Wrote: Yes, I don't really get how some people don't bother with a buzzer 

As I posted in another thread, buzzers don't work for me due to hearing loss.  And, most of the time if I crash I will be miles out, again a buzzer no worky.  But a Marco Polo tag is about the same size and weight as a buzzer, that works for some of us.

(22-Sep-2019, 01:54 AM)SnowLeopardFPV Wrote:  

You must have really good eyesight to see what I look like in that fly-past  
 

Well, I couldn't pick you out of a police line-up.....but general body make up is different than I had you pegged for....

Glad you got your quad back! I've gotten into the habit of pointing the TX ariel straight up as soon as I get it out of the case. If I don't do it right away, I forget

Man, I really must write up my most horrible scraggle story for the general forum. Bloody was literally spilled.

I think I can count myself lucky that it didn't end up further out into the middle of the field because I fear that my buzzer could have been useless in that scenario. Traipsing around in that stuff up to your chest isn't a whole lot of fun even when you do know where the quad is, let alone when you don't. At least it wasn't brambles.

You should definitely post up your story Everyone loves a good read now and again which breaks from usual full on techie discussions, and it's why I sometimes post an essay of an experience I've had. It's always good to put a smile on other people's faces, or to try to help stop them from getting into the same situation

A GPS module will be going on my quad as soon as I can come to a decision on which one to get.

My birthday is also looming and I haven't been able to think of anything in particular that I need, so I'm now in the process of researching Crossfire options because that could be a viable present idea 

hey mister SL FPV! thanks for sending me this link of lessons learned!

first off i have a flysky FS-i6X which i believe has two antennas, although not diversity transmitters. one is for TX function, the other for RX function as it has basic telemetry features like RX voltage on the display and weak signal beeping on the TX as well during flight.

i believe the larger antenna located internally in the top handle bar is the TX whip which is always horizontally oriented unless you hold the TX on a most awkward angle. ergo the null point is almost nowhere near where your aircraft will be flying at any altitude higher than your body position.

the RXLOSS events i encountered were all momentary where i always gained full recovery. these were more likely caused by the dismal SPI receiver only. my crashes were mostly due to the dreaded death spins and a single pilot error disarm in mid-air!

i just had to respond to this thread guided by the virtues you praise of the ever important BUZZER! the new release of HM crux3 came with this very useful feature which has proven its weight in gold from my experience. i fly in a modestly manicured patch of vacant residential land about 1000sqm area where at worse the grass and weeds manage to grow up to 4-6in when the regular trimming goes amiss.

case in point: i have either lost or spent countless moments of my life looking for the very tiny crux3 in this rather small patch of land had it not been for the most precious buzzer beeping its way into my open arms! it is indeed countless as i am still diagnosing the darn thing of its “death spin dilemma” to this day which is for the most part seems already almost fixed. but just a few days ago, i spent more time flipping into the ground uncontrollably sooo many times i could not care to count anymore. even with the modestly loud buzzer, unless you have a general idea of where the quad actually hit ground, you may even barely hear it against the area’s noise floor of wind and vehicles passing by. once you do close in on the buzzer, when the quad is settled deeply into the short grass, you still have difficulty seeing it right there in front of you! it is really that tiny!!!

as a note to myself, i am even going to watch your geprc phantom reviiew again to learn buzzer installation when i get one in the near future.

cheers!