Apprentice S15e Goes Rogue??
 

I have been flying on the Apprentice S15e for a few months now.
For most flights, it flies the way it should, with or without the Safe being fully engaged.
The plane is usually very stable and predictable in calm and in moderate winds.
I try to fly as much as possible in the Intermediate mode with Safe mostly disengaged to improve my flying skills.

I have had 3 separate occasions in recent weeks where the plane became very uncontrollable with the Safe engaged in beginner mode.
Thanks to assistance from others, I was able to get the plane landed safely.
My last flight out after using 3 out of 4 of my fully charged and balanced batteries and having 3 very good flights, on the 4th battery, about 4 minutes into the flight the plane went rogue and was very uncontrollable.
Fortunately again I got the plane landed with no damage.
I change nothing in the Tx programming before or during these flights because the plane was responding well to my Tx commands.
Also my Dx9 Stealth Tx was fully charged when I started the flying session that day.
After pulling the battery (which was still ~80%) and replacing the same battery in the plane, I resumed flying again and the problems had cleared and the plane flew well again.

I never though much of this, but after this last close call, I feel there may be something wrong with the Safe Rx which comes with this plane.

Has anyone else experienced the similar 'rogue, unstable, uncontrollable' behaviour with their planes with Safe Rx installed?
Was your problem a one of or did it reoccur randomly, such as mine has??
What do you suggest to solve this problem from reoccurring again and almost certainly resulting in damage to the plane???

If the Rx may be faulty, I am willing to replace it with another new Rx to test this theory.

Please help and advise.

Thanks,
Mike Fry
MAAC Member #89837
Apprentice S15e (my primary trainer)
Spektrum DX9 Stealth

Re: Apprentice S15e Goes Rogue??
 

Its not loose in the fuselage, is it?

Maybe the double sided tape is not holding in the cold?

Try wiggling the RX and see if its not loose.

Also on another thread here, there was an issue with the servos (or the aileron throws?) Cant remember off hand but I know others have complained about this same issue and it is fixable.

Re: Apprentice S15e Goes Rogue??
 

Maybe it's the BEC and the rx is basically rebooting and then it does not have the stability while "setting up".

I flew one when I was told the safe part was turned off, did not wait the few seconds for it to set because it was disabled. Well it was not disabled and the only thing that did not work against my inputs was the rudder, so I steered by the rudder, used almost all down elevator to land and returned it to the field. Don't want to do that again.

Hi there I am new here. I have an apprentice s15 e. And mine also did that. Usually about 5 mins into flight elevator would momentarily lock up or down. Then work fine. After 2 hard crashes a new motor and a plane rebuild I did a rest run of functions with plane secured to ground. Everything appeared normal then 7 mins into my test the elevator went down and this time it stays down. That little 13 gram cervo actually ceased up. Took it apart all grease was at one end of servo ( inside). Replaced with larger hitec digital servo. Works great. Now the problem is for me I don't trust that little grey 13 gram servo. And well they are used for ailerons as well. Now I am just waiting for them to fail as well. Check those servos. Hope that helps. It is what happened to me.

Re: Apprentice S15e Goes Rogue??
 

When you loose control what does it do exactly? Does it just hold the previous inputs and doesn't respond? Does it set a specific attitude? Do some servos jitter? Is the esc very hot when you land? Has it ever crashed or been repaired? Have you ever knocked a control surface when getting the plane to/from the field?

My guess would be, as mentioned above, a servo that is going bad and either not responding or binding and causing a high current draw causing problems for the bec.

Re: Apprentice S15e Goes Rogue??
 

Not personally familiar with that system, but have some suggestions on where to look.

If the receiver has an LED, check after one of these events to see if it is blinking. That is usually an indication there has been a Loss of Signal event, either due to range, a problem with the Tx or more likely a rebooting due to a power issue. Some receivers seem to be more sensitive to voltage sag and can shut down and restart if it drops to that point.

As to why that happens there could be several reasons. First is that your main battery is discharged too far. You seem to be on top of that so not as probable unless one is starting to fail.

More of a concern is cooling. A lot of manufacturers bury their ESC/BEC inside the fuselage and do not provide adequate airflow.

NOTE: When looking at the specs on an ESC/BEC, they are usually rated only with the proviso there is a minimum 5 MPH cooling airflow. Without it and their ratings will be severely reduced. Also, an ESC can actually heat more at part throttle than full, so moderate throttle control is where you need cooling the most.

Another check would be to feel how how the ESC is after one of these events or even at the end of a normal flight. If too hot to touch then that has to be dealt with immediately.

The reason for this is there is usually a temp sensor that can shut down the BEC output to the flight system if too hot. That heating can bleed over from the ESC at part throttle or from trying to deal with a low battery or too high a current draw.

And now to the final check. Most onboard BEC setups like this are really only rated for 3-4A output and a large number of servos or supplemental systems can push that to or over the limits. This is especially true with digital servos, which by design are current hogs.

Your stability system is likely making small servo inputs on a relatively rapid cycle, more than would be expected with a completely manual setup. Due to this the servos can overheat and fail, or wear out prematurely, (position pots). One test would be to have them move slowly and see if there is slop or erratic behavior. This will likely be around center as that is where the system works the most.

That servo heating from rapid cycling is dealt with on some by purpose built controls, motors and cases with cooling fins. With a normal duty or lower cost servo having the body buried in the foam, you can imagine there would be no opportunity for it to handle a high-cycle workload.

Unfortunately from your description of going rogue not much to determine which control(s) are acting up. It may be only one servo and if driving hard over to one limit or the other it can also increase current draw on the BEC, affecting it as described earlier.

This may be difficult to simulate on the ground with the plane static as the system will not be under the demands it would see in flight, but it may show something significant.

Re: Apprentice S15e Goes Rogue??
 

What about sloppy controls or loose control surfaces?


Also flying too fast can also cause problems with control oscillations.

I fly my apprentice s15e which is now a 25e 6 batteries a day. Excessive, yes and that is OCD for ya. But I am on short term disability and it is very therapeutic. Having said that she gets a lot of air time. I am becoming quite familiar with the plane and its quirks. I wanted to add to my other post that at first I to thought it was the reciever because it was occurring so randomly and started out as an occasional hic up. But when that servo ceased up before my eyes I was so glad I hadn't flown again bassed on a quick pre flight test. Like I said all appeared fine and good to go. Those servos do work extra hard when in safe. Hey I hope ya figure it out. I love that little apprentice. Good Luck

Gotta go charger just beeped. Lol

Re: Apprentice S15e Goes Rogue??
 

Thanks for reply.
My Rx was mounted in with either silicone or hot glue when purchased.
I check it regularly and it is still secure.
I will review the other thread you sent links to.
Other than this one (important) issue, the plane is a great trainer and I would highly recommend it to anyone just starting to fly.
Regards,
Mike