Crashed my FPV tricopter again today at the same place as last time. I was high up and had good reception, but then lost R/C and got to see it fall backwards to the ground until I lost video signal.

This was high brush and a large area. I had a general idea (200 meter diameter area) of where it went down, so I grabbed my ground stattion and set off to get it. The ground station is powered by a lipo and and I grabbed an extra pack just in case.

I have a 500mW 1.2gHZ video system with home-made IBCrazy circular polarized Cloverleaf and SPW antennae. The CP antennae are so good that it makes radio directional finding tougher than it needs to be. I have to toss a monopole into the case to help in future crash recoveries. I used the body shield method to locate it (a method I read about only two weeks ago right here on RC Groups!!!). I held the antenna up against my chest and then slowly turned until I got signal degradation, then I would slowly go back and forth a few degrees until I got a firm direction. The bearing was where my back was facing at peak signal degradation. After narowing down the area, I began a couple of passes. On the third pass, I walked right into the model. The grass was so high that I could be standing three feet away and not see it. I was amazed at the accuracy and precision of this technique!!

I suspect an ESC failure (the one acting as BEC for the RC RX), but will need to confirm.

I got lucky and still had video signal! At least the body sheilding technique works perfectly!! I didn't lose my gear and it will be flying again in no time.

I'm hugely relieved!!

Calvin

Odd. In reviewing the GoPro Hero HD footage, the recording stops just before the crash, but I saw the crash on the googles.

The GoPro gets 5V from the KK board (along with the RX - all fed by the suspect ESC). The Fox800 VTX get's it's power from a 12V step-up that gets it's feed directly from the 3S lipo.

I'll have to do some tests on the bench to try to reproduce what I saw happen.

I used the same technique yesterday when my FPV quad crashed in a field. Worked perfectly!

When I crashed my EasyStar in the woods a month ago I did the opposite. I used my body as a reflector, which gave me a faint picture in one direction. Without reflector the cloverleaf did not pick up any signal at all. After a couple of 100 m I found the plane, pierced with pine needles...

Glad the body blocking technique I described, worked for ya.
As for the GoPro recording. It has to buffer a large chunk of the video (20-30 seconds)
in memory before writing to the card, so if something interrupts the recording such as a large
impact that ejects the SD card, you'll lose that much of the video.

ian

Thanks Ian - If I hadn't read what you posted, I would have lost it for sure! The grass it crashed in was about 3 feet high.

Thanks also for the info about the GoPro. That explains it perfectly! The card was partially ejected when I found it. I use a Layerlens and the rubber bands and Velcro weren't covering the card slot.

XDreamer - good to hear about your success! Good tip about using your body as a the reflector too.

A high gain helical would make fast work of radio direction finding. I'm going to make one up.

In hindsight, it would have been a great idea to test this technique out in controlled conditions before having to try it for real.

Really loving the body shielding thing! Any chance somebody can post a link to the first description by Ian ? Thanks !

You peeps always loosing your multicopters in brush really need a discovery beeper set to activate in failsafe.

I think you need both to be certain. Body shielding works only as long as you have video signal and a beeper only works within audible range.

All methods rely on power, so speed in location is critical. If the lipo detaches in the crash, finding it will be much, much harder (e.g grid search).

When doing the body shielding with the CP antennae, I found the signal glitch was in a very small range. It was easy to miss it by turning too quickly. Once the signal blip was seen, I scanned back and forth within a few degrees each way just to verify that the blip stayed in the same direction. Then I sighted on a tree in the direction and walked that bearing.

It took a bit of trying before I realized how small the blip was. After that, it went quickly and was very precise (I walked right up to it).

Originally Posted by Jack_LaLanne

Really loving the body shielding thing! Any chance somebody can post a link to the first description by Ian ? Thanks !

Think this is it

Originally Posted by crezzee

Think this is it

That's where I saw it. Very timely!