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Anyone having inexplicable Apprentice 15S Crashes?

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Old 06-30-2014, 01:44 PM
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Len Todd
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Default Anyone having inexplicable Apprentice 15S Crashes?

Our club has 9 Apprentice 15Ses (with SAFE). We use several of them for our school program and have several members who fly their own. We have had seven inexplicable crashes with experienced pilots on the sticks. What seems to happen is from Straight & Level flight, the plane noses down to 60 degrees and then there is no control. I have one that has crashed that way 4 times. On that plane, currently, both Aile are locked fully down and the Elevator reversed on it own during mid-flight. I have tried these with the RTF DX5es, Dx6is, DX8s and DX9s. Sooner or later, the three involved planes crash. Last night, a 4th plane went into down elevator as it was sitting on the ground energized waiting to takeoff. I reinitialized it and it corrected itself. Yes, we keep them stable during initialization. I have a couple dozen electric planes, so E-Planes are not new to me.

Oh, ... This last week I have been fighting an AR 635. It inexplicably develops twice as much down elevator and it also locks up the motor. When testing on the bench today, it actually locked up the motor and then tried to run the motor backwards after a lockup. I have a couple other AR 635s that work great. I replaced this offending one with an AR600 and the plane works correctly.

Today, I sent these Rxers into HH. But, I want to ID if anyone else is experiencing these types of problems with SAFE and Spektrum gyroed Rxers.
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Old 07-30-2014, 05:14 PM
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kevink47
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I have a 15s and a month ago it had been flying fine and all at once the wings rocked and started to porpoise and any input to recover failed.Found the plane 2 blocks away in a bush.(no damage)I discovered that the battery had a shorted cell and was puffed up.Apparently when the voltage was unbalanced the receiver went crazy due to a low voltage condition.You may want to check your batteries.Since replacing my battery there have been no issue.Hope this helps
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Old 07-31-2014, 11:11 AM
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There was a flyer with an ~ 1 year old Apprentice that has experienced 4 crashes, last one was two days ago. This time the plane went into a spin and must had flatten out before hit since it was just sitting in the field where we recovered it. Propeller wasn't even broken. When I got to the plane, the propeller was wrapped with grass and there was a beeping I am guessing from the ESC since the motor was trying to spin still and I could feel that the motor was extremely hot. I turned off the plane (receiver switch) but did not disconnect the battery. When we got the plane back to the flying field, everything EXCEPT the motor worked so voltage was getting thru the ESC to the receiver but the motor would not spin. Don't know what failed there but if the ESC had failed, then that would explain no control. We disconnected the battery since I think it was still powering the motor since the motor was not cooling off. The battery cell voltages were all within a tenth of each other and consistent with the flight time use.

As I stated to begin this, the user has had 4 crashes. Only one was sort of explained due to a battery cell going bad. The rest do not have a root cause. I expect that either the ESC is intermittently not supplying power to the receiver or the receiver is intermitted.

What I am afraid of is the user will find that the motor is dead, he will replace it and continue to fly and have more crashes due to the ESC or receiver.
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Old 08-10-2014, 06:35 AM
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This is my dad's plane of choice and we have had several instances where the plane just goes crazy. It seems like it always happens on the second flight (?) The plane starts to porpoise almost vertically. When it happens, you have almost no control at all. We have totalled this plane 5 or 6 times and I will say it is a tough design and easy to fix. Definitely an issue with the SAFE system. Enough so that we jokingly wrote "UN"safe on the side with a sharpee.
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Old 08-10-2014, 06:41 AM
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Originally Posted by PHerder View Post
There was a flyer with an ~ 1 year old Apprentice that has experienced 4 crashes, last one was two days ago. This time the plane went into a spin and must had flatten out before hit since it was just sitting in the field where we recovered it. Propeller wasn't even broken. When I got to the plane, the propeller was wrapped with grass and there was a beeping I am guessing from the ESC since the motor was trying to spin still and I could feel that the motor was extremely hot. I turned off the plane (receiver switch) but did not disconnect the battery. When we got the plane back to the flying field, everything EXCEPT the motor worked so voltage was getting thru the ESC to the receiver but the motor would not spin. Don't know what failed there but if the ESC had failed, then that would explain no control. We disconnected the battery since I think it was still powering the motor since the motor was not cooling off. The battery cell voltages were all within a tenth of each other and consistent with the flight time use.

As I stated to begin this, the user has had 4 crashes. Only one was sort of explained due to a battery cell going bad. The rest do not have a root cause. I expect that either the ESC is intermittently not supplying power to the receiver or the receiver is intermitted.

What I am afraid of is the user will find that the motor is dead, he will replace it and continue to fly and have more crashes due to the ESC or receiver.
Update on the flyer I reported on. He has had his fifth crash that totaled his Apprentice. He lost all control, again, and it went straight down into hard packed ground and exploded. He was so bummed out that he is getting out of the hobby. He has heart problems and money is tight and he just cannot justify the expense.
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Old 08-10-2014, 09:06 AM
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Originally Posted by PHerder View Post
Update on the flyer I reported on. He has had his fifth crash that totaled his Apprentice. He lost all control, again, and it went straight down into hard packed ground and exploded. He was so bummed out that he is getting out of the hobby. He has heart problems and money is tight and he just cannot justify the expense.
Sorry to hear that.. Do you think Parkzone knows about these problems? Maybe they would replace it or at least send him some parts.
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Old 08-10-2014, 09:58 AM
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Originally Posted by gunnut View Post
Sorry to hear that.. Do you think Parkzone knows about these problems? Maybe they would replace it or at least send him some parts.

They would have to send a complete plane. He offered me the wing that was ~ 7" shorter than stock. The rest is either damaged (motor, battery) or not trusted (SAFE Rx and ESC), don't know about the servos. He is planning on selling his Txs (Spectrum DX5e and DX6i (I believe)) since they weren't destroyed in the crash.

He is pretty bummed out since everytime he tries to fly, he is bringing home pieces (several planes) so he is quitting. I thought he could just get a BNF plane to continue flying but money is tight for him and it seems that the only luck he has is bad.
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Old 08-18-2014, 05:32 PM
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After flying Apprentice with SAFE technology, for over a year, yesterday i nosed it into ground at 60 degree angle. I was shocked, I totally lost all control and it happened so fast I didn't use the panic button. Not sure it would of helped in this situation. It is repairable but now I'm concerned of issues with the signal or electronics. I was only 50 yards away from plane when it came down. Still in shock and looking for answers. I have a DX5 transmitter that came with this plane and have had no problems until now. No answers at this time.
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