View Full Version : DX7 Unknown Crash

12-08-2007, 10:05 PM
So I went up this morning with my new DX7 and 2.4ghz video system from Future Hobbies. Flew just peachy for a minute or so, and then I went straight in front of the antenna (I have one of the Diversity Antennas) for better reception. I had some dipping issues and then it seems to have lost control. Plane dropped the digital camera (fell off plane) and then it porpoised for a bit. Managed to swing it around a little bit but then it flat out nose dived into a sand dune. I need to figure out what happened. Is it the video system? Here's what was different about this flight:

1. Had a new LiPo a little bigger (size, not electrically) than my normal ones. Due to the size, the battery was mounted vertically rather than horizontally (as I always do).
2. Had a digital camera on the back for pictures (always put it there) but it came loose during flight and landed in the dirt (whew!!!) - about 15 seconds before the plane went out of control.
3. Used new DX7.
4. Used 2.4ghz DX7 with 2.4ghz video system...

I repaired the plane and went back out this afternoon to fly again to see if the DX7 set was faulty. Flew high, fast, etc and never had a single issue. I only used the standard electronics with my normal horizontally mounted battery. No extra weight, no oddly placed batteries and no wireless video.

Is it possible that I need a 900mhz video system? Or did I completely screw up and unbalance the plane by having the battery mounted vertical? Did the loose camera possibly cause some instability and why couldn't it have fixed itself after launching my SD1000 some 500 feet up?

(BTW, the digital camera survived and works quite nicely. Kudos to Canon)

12-08-2007, 10:10 PM
I'm really not sure. I don't think it was the camera, because 2.4ghz systems arn't meant to be affected by each other. Perhaps run some tests on the ground with the camera on the plane?

12-09-2007, 01:07 AM
Which receiver? UBEC or not?

12-09-2007, 02:48 AM
Here's a guess. The plane "went out of control" after the camera fell off?
I'd say it was due to the change in CG like you mentioned.
I'm not sure what you mean by "fixing itself". An unstable plane is gonna be a handful.

I really doubt it's the 2.4ghz camera.
The 2.4ghz band has strict "limits" and devices aren't allowed to interfere with another 2.4ghz device.
If you ever went "wardriving" you'd be amazed how many 2.4ghz Wi-Fi devices are out there and they don't interfere with each other, much.

12-09-2007, 05:19 AM
Thanks. Seems like it was a stupid mistake, but I wanted to confirm. I'll be back out to try again tomorrow.

12-10-2007, 05:10 AM
Well, just a conclusion.
Went up today for about 10 seconds... receiver suddenly stopped taking commands and it leveled off and flew into the ocean. Plane is now MIA.

For whatever reason, the video system was swamping the AR7000 RX. Video was set to channel 5 and the TX/RX... well, that was supposed to work.

12-10-2007, 05:54 AM
Sorry to hear that ),:
I always spend a lot of time tweaking the plane before I do any high altitude or over water flights.

Was the camera powered from the RX by any chance?

12-11-2007, 07:09 PM
900 Mhz is the only way to go with the DX7. Too many people have had too many problems using 2.4 Ghz cameras w/spektrum. I have heard that separation of antennas helps, but you can only separate so much on a airplane. If the rx's are to close you will have bad things happen. Go 900 Mhz and use your 2.4 Ghz cameras with your old 72 Mhz radios.

12-11-2007, 07:12 PM
Would have been nice to know before it went on a nice sunrise flight into the ocean...

12-11-2007, 07:13 PM
Camera wasn't powered by RX - it had its own lipo.

12-11-2007, 07:14 PM
Check out the AP forum, its been mentioned alot since 2.4 Ghz radios hit the market. Your not alone, alot of guys found out the hard way and although bad for them, it might help out the next guy.

Are you going to try it again, with new equipment?

whats an ocean? :p jk

12-11-2007, 07:16 PM
Would have been nice to know before it went on a nice sunrise flight into the ocean...

your failsafe didnt kick in?

12-11-2007, 11:16 PM
Ouch. Bummer man. Hate to hear that. If it makes you feel any better, I lost a camera, too ... only with mine, I left it on the side of the road after I stopped flying to take a picture of a hawk, and then I left it there and someone had jacked it by the time I remembered and came back.

I love how devices always have that FCC Rule stamped on them: (1) this device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.

I sometimes picture the people who work at the FCC running around in pirate suits saying, "Garr, they be more like guidelines, really ..."

12-13-2007, 05:42 AM
lol... I think that pretty much sums up the FCC.

Now if I fly over a bunch of houses with 2.4ghz routers, should I draft my emergency landing procedures beforehand?

12-14-2007, 07:57 PM
did you do a range check when you had both 2.4 Ghz systems in the plane?

12-14-2007, 07:58 PM

12-14-2007, 10:29 PM
I think you would have seen it if you did the range check. I dont do it everytime either. Your supposed to hold the bind button as you walk away.