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Old Jul 24, 2013, 09:52 AM
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2.4G "Shot Down" by interference?

Guys, this past weekend, my brand new Tiger 2 lost its life due to what can only be described as "shot down" from interference...

Take-off was normal and true. I turned left to have it come back towards me. No issues. It was cruising at approximately 40 mph and straight-and-level. It had reached an altitude of about 150 feet and was passing by me about 200 feet away and 150 feet in altitude. THEN, it turned right, flipped upside-down, and lawn-darted into the field. Control inputs of any kind were useless in the 1.5 seconds it took to hot the ground.

Here are some specs on my equipment:
-2.4 G Spektrum DX7S
-O.S. 55 AX
-CG Tiger 2
-JR On/Off switch
-1,900 mAmp battery pack with 90% capacity verified post crash.
-5th flight of its life. Previous 4 flights had no issues.

Here's a picture I took just after its maiden flight from last week:
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So what the hell happened?! Are 2.4G radios DANGEROUS???
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Old Jul 25, 2013, 01:02 PM
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Goodnight Irene
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2.4 is not any more dangerous than the old 72MHg was. Some will disagree with me on that. Check your switches and all connections. I had a flaky connection in a plug on my switch. It was the plug from the switch to the RX. It acted funny on the ground and when I check the plug connections it straitened out. Thought I just had not plugged it in completely. The next flight the plane died.

EDIT; Give his a good read. Much wisdom here IMO. http://www.rcgroups.com/forums/showthread.php?t=1963025
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Old Jul 25, 2013, 09:04 PM
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Plots, I've have had the same issue with some of my radio gear, namely Orange RX and Spektrum. I have heard of quite a few people having issues with DSM2 both on Spektrum gear and any other compatible TX/RX units.

For this, I have changed my radio gear, (tx module and rx units) to Corona DSSS.

I had the following issues: (and these failures have been Nitro, electric, and gliders)

Could spend 10-15 minutes flying then model just falls out of the sky, no correction could be made to flight path.

Models would fly for 2-3 minutes then have then same reaction. No modes of interference, no power lines, phone towers, and all my mobiles turned off, and flying alone.

Didn't matter what type of RX unit was being used, failures would happen at its pleasure.

Changing TX Module had no effect.

Since changing my Module and RX units out, I have never had the same issue. Never had drop outs / Brown outs, and have flow the models in the same location on numerous occasions. I am of the opinion that DSM2 is the real culprit.
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Old Jul 25, 2013, 09:57 PM
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Hard to say what the reasons are.

My only 2.4 I have is a old 6i on dsm2 and I fly all kinds of glow airplanes with it from a old Kadet to a 118mph low wing similar to your deceased Tiger and lots inbetween.

Environmental reasons such as powerful transmissions could obliterate your signal and at speed a crash can happen quickly. Doubt FM would be any better in that situation.

I do believe that 2.4 "Spektrum" anyways is not all that its cracked up to be. Have witnessed a few unexplained loss of control issues with mates that are all using the new 8 and th DSMX... I don't think I'll ever abandon FM.
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Old Jul 25, 2013, 10:55 PM
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Is there any way to check the radio and receiver (other than the retarded range check)? I am planning to call Spektrum and ask them about my symptoms and what could be the culprit.

In the meantime, I am putting together a Hanger 9 Piper Pawnee ARF and reusing the same engine and radio... What a terrifically put together aircraft. I couldn't build it any better for sure!
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Old Jul 25, 2013, 11:08 PM
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...And the location of where I was flying the Tiger was VERY remote. No phones or phone lines, no electricity or power lines, and no neighbors for 5 miles in any direction in the Sierra Nevada mountains. Basically just paradise. Should not have been any interference of any kind.
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Old Jul 25, 2013, 11:26 PM
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I'm putting together a Hangar 9 Cub and using FM. Have seen too many issues lately where I fly to have something this expensive go in for no real reason.

You can use AntennaSearch.com to find out what is in your area although it sounds remote but you never know.

The range check you speak of is the Reduced Power Output check?
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Old Jul 27, 2013, 12:11 AM
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Check to see if your servos still work. I have had servos go bad in flight on two occasions. They went full deflection and would not respond.
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Old Jul 28, 2013, 10:16 AM
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I had a nice, long discussion with Spektrum earlier this week and the result was to ship back my radio and receiver to them to check it out. We'll see what the verdict is...
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Old Jul 28, 2013, 12:48 PM
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I have seen this happen many times in the Spektrum line of radios. Most at my field are leaving them.
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Old Jul 29, 2013, 03:50 AM
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I take it most at your field then are on DSM2? I've not heard as of yet the same fault happening with DSMX.
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Old Jul 29, 2013, 07:30 AM
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One single guy where we fly had had a couple of unexplained crashes with the DX8. The last one his transmitter was giving him a strange code error.
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Old Jul 29, 2013, 10:02 AM
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Yeah, I'm finding out that Spektrum is still a kind of beta testbed for JR customers. I really like the ergonomics of the DX7S, though. Perhaps I will look into Airtronics, Futaba, or some other manufacturer...
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Old Jul 29, 2013, 01:05 PM
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By the way, thank you all for your interest in this topic. I would like to know what TX/RX combo you all personally spend your money on to fly and have confidence in it.

THANKS!
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Old Jul 29, 2013, 01:11 PM
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A lot of people use Spektrum with no problems.

Best bet is to get a data logger so if it happens again you might get some useful data on the cause.

I like hitec radio gear. I use the Eclipse 7 pro.
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