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Old Jan 12, 2013, 11:38 AM
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My New HT-FPV just crashed after flight 3! Why?

SO..

Back number three.. in GPS mode.. everything is going great.. I start some faster forward flight.. everything is okay... then, towards the end part of the flight (9min on 4S 3300MHH) I am getting closer to the ground.. and the thing start dive bombing at an 45-deg. pitch.. slams into the ground (grass). Then, I notice the rx (AR6200) is blinking? But, there is (seems) to be radio connection as I softly spooled up the props to confirm?

??

I have a 9503 radio.. and in fact, I have a JR R921X rx that came with it.. maybe I should use this rx? Maybe its a better unit? What happened?
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Old Jan 12, 2013, 04:21 PM
Just Keeping UP
United States, ID, Moyie Springs
Joined May 2004
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If you do an internet search on 'AR6200 blinking', you will find that the receiver is telling you that it's power has dropped off and then been restored. The obvious is that you are running your battery down to the point that the BEC turns off, you crash, the motors are then off, the battery voltage rebounds, the BEC turns back on, and the receiver flashes to inform you of what happened. Many pilots blame this on many things other than themselves.
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Old Jan 12, 2013, 04:30 PM
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Are you using a LiPo alarm of some kind? Sounds like what nfhill said to me, battery dropped in voltage being close to empty (even more likely in forward flight, drawing more power than in hover), a motor or two shut down momentarily, voltage was restored but the momentary shutdown put the copter into the dive and it couldn't recover in time.
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Old Jan 12, 2013, 04:33 PM
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On a quad weight isnt a limiting factor if you think your having brownout issues ( and it sounds like you are ) throw a small 2 cell and a bec on it and give it a few more flights i bet the issue is resolved
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Old Jan 12, 2013, 04:38 PM
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Interesting. Your right I did read that.. So basically, your saying that I flew for too long and the voltage to the rx fell too low and in lays the issue. The other interesting thing is that the LED on my naza was still green, and did not indicate low voltage at this time. Previous flights I actually hovered the pack to the red LED to inform level one voltage has dropped and I had no issues with the RX.

I also have see. You tube videos where they tested the AR6200 and it started to blink for other causes then voltage.

In any case.. Had this been a better rx (such as the JR X9102 ) would this have gone into fail safe? The AR6200 did not support fail safe.
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Old Jan 12, 2013, 04:38 PM
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search "Spektrum Sucks" on this forum.

I have a DX8 but I only use it on my parkflyers and short range quads. I had a similar situation with a quad and an AR6200 DSMX with a satellite and telemetry..
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Old Jan 12, 2013, 04:46 PM
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Here is what happend man. And this has happend to me and my HT-FPV too.

You were running low on batteries and the Naza is set to default to bring it down at a certain point. You reached that point. You'll notice it starts to drop then when or if you try and bring it up and keep going, this can result in a crash if you arn't prepared for what the Naza will do.

Even though I agree that Spektrum sucks, I think this is a purely Naza issue and can be changed in the Voltage section of your Naza assistant.
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Old Jan 12, 2013, 04:48 PM
Just Keeping UP
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The fact that your FC didn't indicate a problem only means that its power voltage requirement is different from the receiver's requirement. Yes, the receiver uses flashing for other problems too. Study the receivers specs.

The Spektrum radio is not the source of your problems. Operate within the specs and it will work fine. Different systems have different specs. Blaming the radio is a cop-out to avoid learning to operate within specs.
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Old Jan 12, 2013, 04:55 PM
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Great! Thanks for all the info! I do love learning all about this stuff! So I think my cut offs are 14.45V for the first one.. And then 13.45 for the second one. I am using a 4S 330mah batt. This issue happend about 9min into the flight. And I was moving forward vs hover. So this is making more sense.

Let me ask.. I think the rx can run on as few as 3.?V. So, why on earth would this ever be an issue when there is plenty more in the main pack?
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Old Jan 12, 2013, 05:03 PM
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Quote:
Originally Posted by Tharr62 View Post
Great! Thanks for all the info! I do love learning all about this stuff! So I think my cut offs are 14.45V for the first one.. And then 13.45 for the second one. I am using a 4S 330mah batt. This issue happend about 9min into the flight. And I was moving forward vs hover. So this is making more sense.

Let me ask.. I think the rx can run on as few as 3.?V. So, why on earth would this ever be an issue when there is plenty more in the main pack?
My guess is the Naza just set off the warning light on ur rx. That doesn't happen to me only the Naza light flashes red when it's low and wants to land.

I'm guessing you meant 4S 3300mah. I also fly with one of those. It isn't the pack being empty so much as the Naza telling it that it should land and regulating the power to everything including the rx
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Old Jan 12, 2013, 05:11 PM
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This is very confusing. The rx only needs a few volts to run? So why is there this issue at all? The main pack even when at the end should have plenty of power, why is the controller telling the rx there is not??
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Old Jan 12, 2013, 06:56 PM
Just Keeping UP
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I'd recommend keeping the receiver supply voltage above 4V, that means keeping the voltage to the BEC above 6V. In spite of all that, it only takes a low voltage spike to cause the receiver's mPU's to reboot. When a battery reaches the low end of charge, its voltage is able to drop under load quite a bit.

A typical multi-rotor has so many noise producing components it's something of a miracle that they work at all. Ignorance is bliss right up to the moment it bites you.
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Old Jan 12, 2013, 07:10 PM
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You don't want to rely on a receiver's fail safe funtion in a multi-rotor. That is barely ok for a fixed wing that doesn't need a spinning prop to avoid a crash. The receiver doesn't know a whit about how to fly a mult-rotor, that's the FC's job. A typical FS response in a receiver is to reduce throttle to zero. Guess what happens when the FC sees that command in manual control mode.
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Old Jan 12, 2013, 07:41 PM
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I meant setting fail safe, so that the naza simply executes return to home is the rx is lost. Which it does really well. So, how can I safely calculate flying times without guessing?
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Old Jan 12, 2013, 08:02 PM
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http://www.ecalc.ch/xcoptercalc_e.htm?ecalc
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