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SAFE Rx setup questions/concerns

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Old 04-13-2018, 08:17 AM
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H5606
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Default SAFE Rx setup questions/concerns

Airplane is a new, E-Flite Apprentice S 15e with stock, SAFE/AS3X receiver - master Tx is a DX9. (Plans to use a DSM2 DX6i as a wired slave for training purposes.)

For the DX9, SAFE mode is on the 3-position, switch B; panic recovery on Bind switch I. Training transfer is on an alternate switch.

Airplane hasn't flown yet and noticed SAFE in beginner mode doesn't appear to begin working until throttle has been advanced after turning on. With airplane sitting static, only see reduction in throw/travel of control surfaces when in beginner mode; intermediate and advanced modes show no difference or reduction in travel. Is this normal?

Setup dual rates and expo on other switches and only notice changes in beginner mode; i.e. switching to intermediate or advanced mode and switching to low rates shows no noticeable reduction in throw when control surfaces move to their extremes. Is this also normal?

Also noticed control surfaces appear to "meet their stops" at some point or quit moving before the Tx stick hits it's limit in intermediate and advanced modes only. Again, is this normal operation?

Last edited by H5606; 04-13-2018 at 08:19 AM. Reason: Clarity
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Old 04-16-2018, 07:19 AM
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Why use wired trainer?!?!? Wireless is so much easier, and it works just fine with the DX9 as the master to a DX6i.

Yes, it's normal operation for all the things you asked about.

I would set up the DX9 in P-Link Master mode. Then the DX6i is just a default model. You control the FM and panic on your DX9, the student just controls the sticks.

My daughter (19) asked me to teach her to fly. We went out two days - 7 flights the first day, 5 the second. By the end of the first day she was nearly ready to solo, and this was with 36 degrees and a 10-12 MPH crosswind. The second day she had 3 solo flights and two landings on the runway.

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Old 04-17-2018, 03:31 PM
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Originally Posted by AndyKunz View Post
Why use wired trainer?!?!? Wireless is so much easier, and it works just fine with the DX9 as the master to a DX6i.

I would set up the DX9 in P-Link Master mode. Then the DX6i is just a default model. You control the FM and panic on your DX9, the student just controls the sticks.

Andy
I happened to have a trainer cable handy to use and am set in my ways, don't like leaving the comfort zone, resistant to technological advances, was satisfied with the setup so far... but your reply got me to try something new...

So I set up the wireless trainer feature as you suggested and agree that it was easy to do; Bind process takes place without leaving the program task. Don't know if necessary but set the DX6i on an unused model-match program before binding the DX9.

Thanks very much for your help, for getting me out of the comfort zone, and for trying something new.

Another observation: tried to set up failsafe on master as "preset failsafe" with all surfaces to max right deflection, up elevator, and throttle off like I've done successfully with other Rx's. Correct me if wrong but suspect the SAFE receiver is already programmed for failsafe and cannot be changed through the traditional means; testing failsafe feature by shutting off the Tx does show slight aileron input and throttle shutoff which satisfies me for this airplane.

p.s.: For those that may search this thread for similar info and avoid any confusion that could occur, realize that I used incorrect terminology for E-flite's Experienced flight mode and called it "advanced" in my opening post.

Last edited by H5606; 04-17-2018 at 04:01 PM. Reason: Correction for terminology
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Old 04-17-2018, 04:08 PM
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Don't worry about the way the RX is acting.

Yes, AS3X doesn't kick in until the throttle is advanced past 25 percent the first time after power up.

Other than that, make sure the corrections are going the correct direction and fly, how it acts on the ground doesn't reflect whats happening in the air where when a correction is applied the airplane reacts.
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Old 04-18-2018, 06:22 AM
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Originally Posted by H5606 View Post
Thanks very much for your help, for getting me out of the comfort zone, and for trying something new.
You're welcome. At the time I developed the wireless trainer interface, I was the main instructor at the club. I had a captive test group

Another observation: tried to set up failsafe on master as "preset failsafe" with all surfaces to max right deflection, up elevator, and throttle off like I've done successfully with other Rx's. Correct me if wrong but suspect the SAFE receiver is already programmed for failsafe and cannot be changed through the traditional means; testing failsafe feature by shutting off the Tx does show slight aileron input and throttle shutoff which satisfies me for this airplane.
Failsafe is handled differently with different receivers. The AR636 does not have the preset failsafe functionality that is found in higher receivers like the AR8000.

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Old 06-07-2018, 08:57 AM
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Last night I had an opportunity to enlist the assistance of a club officer and try out the wireless trainer link - the system is impressive in that it won't allow a student to over-pitch or over-bank the airplane and the airplane flies very well.

Way back when I was setting-up the airplane at home, I noticed significant drifting taking place on the rudder servo and a minor amount on the elevator servo; I tried to ignore this and thought it might be due to a weak battery pack - after adjustment for dead center, from what I can tell, it holds proper position - for a while.

After landing the airplane yesterday, the rudder was deflected at least 15 degrees to the left and hence the nose gear as well - I went so far as to change to a fresh battery with no change in the left rudder indication.

I can mechanically adjust the output arm and linkages to neutralize the rudder but its beginning to occur to me that I'm "chasing my tail".

For the record, I did re-bind the airplane at the field because I forgot there is a master switch on the side of the fuselage... duh. Is it possible my binding etiquette is not up to par and causing this drifting problem?

Is this a common problem or an isolated anomaly?
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Old 06-07-2018, 09:50 AM
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Battery voltage does not cause/effect drift.

What do you see on the tx monitor screens?

What servo? Plane? Receiver?

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Old 06-07-2018, 04:47 PM
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Master tx is the DX9 - w/o touching anything, THR reads -100, AIL:-1, ELE:+3, rud:0, GER:-100, AX1:-100. Using toggle switch A for wireless trainer transfer with master override enabled.

The cursor moves smoothly with no hesitation while following stick/gimbal movement on the primary controls stop to stop.

Three of us shared the flight and half of it was with the slave, DX6i. After flight, aileron trim on the DX9 was showing some right - perhaps to combat the introduction of the left rudder(?) and a small amount of down elevator.

Rudder servo: EFLR7150
Airplane: stock Apprentice S 15e
Rx: IFLR10013
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Old 06-07-2018, 05:09 PM
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OK, I'd rule out the transmitters as suspects. They're reasonably centered and the trainer is tracking them.

So the problem is either the servo or the receiver. You can't rule out the servo quite yet, but my money is on this instead:

At startup the plane does need to be still and level. It will consider "level" whatever attitude you have the plane in when you start up (within reason - it won't let you call a 45 degree bank "level"). If you had it a few degrees off, it would think that's normal.

That's by far the easiest way to screw up, especially if you didn't know about the switch on the side.

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Old 06-08-2018, 08:39 AM
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Thanks - this is most helpful info.

When I get home - with the fuse sitting upside down in a cradle, I'm going to plug in the flight battery, turn it over and set it on the basement floor, switch the Tx on and then the airplane without disturbing it or hooking up the ailerons and see what happens.

If the rudder still shows deflection, I'll rebind to the airplane and if the rudder still isn't faired, reposition the output arm on the servo for true center, make adjustments on the clevises to achieve rudder/nose gear neutral, then leave the system on for a while. If it drifts, I'll know I still have a problem.

Telling all these details just in case there may be an "Aha!" moment and a "Here's what you're doin' wrong or shouldn't do..."
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Old 06-08-2018, 09:45 AM
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Do you happen to have a servo pulse meter? That would tell you if the receiver is commanding off-center, or if the arm is just on the spline shaft wrong.

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Old 06-09-2018, 11:04 AM
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Yesterday, I did what I said I'd do and the rudder was much better. Advanced the throttle to get the system active, moved the airplane around, and watched the rudder closely to see any changes or drifting. It was close to neutral; just 3 turns in on the clevis made me happy and I decided to fly it.

At the field, the only change to start-up was to introduce ailerons by adding the wing. When I switched on, the #@*&%! rudder went so far to the left that even full right trim at the tx wouldn't get it to neutral. Several retries failed to get the rudder to neutral.

This morning, I used a servo driver to operate both the rudder and elevator servos and confirmed both to be one spline forward from servo neutral (this is a change I made while setting up the airplane to get geometry to what I think is correct and what I've been doing most of my life flying 72 MHz...) I also rebound the system without any improvement.

Does SAFE and/or AS3X need the servo output arm to be at servo neutral to operate properly?
Switching back to servo spline center seems to exacerbate the problem.

Is the pushrod one piece of wire in a sleeve?
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Old 06-09-2018, 03:43 PM
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The pushrod is a single wire. The case is there to keep the wire from flexing. Test it - pull and push on the ends and see that they're 100% connected.

Center all trims on the transmitter before binding. Get rid of any Sub Trim if you have it. All should be at 0.

If your servo driver has a meter, use it to measure the pulse coming from the receiver. It should be 1.500ms. The receivers do a dance when things are starting up. Is that happening properly for you?

What is "servo spline center?" I've never heard that term before.

The servos should be set up such that the control arm is 90 degrees to the body of the servo when the servo is commanded to center (1.500ms). If the control surfaces are not at the correct center point, then you adjust the clevis so that they are. If there's not a spline position that exactly matches the 90 degrees, then you get it as close as you can and adjust the clevis to make the surface neutral.

With an AS3X system you should not use nor need trims. The system learns what center is from the transmitter when you start up, or when you hold things slightly off-center position for 2 seconds.

I really don't like that old receiver design. If it were me, I'd toss that out and put an AR636 in.

Andy
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Old 06-09-2018, 06:07 PM
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Understanding now that the pushrod cannot be growing longer and that the case on the pushrod wire is a stiffener for a solid wire only and not a guide tube.

Sub trim is all at 0.

The servo driver is a cheapo unit that has a neutral position that I'm taking for granted is 1.5 ms. The receiver does it's dance when starting up and the ailerons always seem rock solid - i.e. no drifting.

Servo spline center is something I conjured up to describe optimum position of the output arm/wheel to give - in this instance equidistant movement of the surface in both directions which ideally would mean the pushrod pivot point should be tangent to the arc of rotation or perpendicular to the output... oh never mind - I'm confusing myself here... I didn't know what else to call it.*

Recalling that some Airtronics and JR servos had a pot adjustment screw accessed through the center of the output shaft that allowed fine adjustment of servo output arm/wheel so that you could achieve a desired neutral point even if you were a half-spline off in either direction.*

*When indexing servo with output arm position as a reference for 1.5 milliseconds.

Sorry for my level of frustration and continued questions; wondering if the AR636 has SAFE because I really like the feature for training purposes.

Last edited by H5606; 06-10-2018 at 04:41 AM. Reason: Clarification
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Old 06-10-2018, 10:01 AM
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There is no pot adjustment in modern servos. We had that back in the 1970s. Haven't seen it in decades myself.

I'm inclined to think that you have a bad servo. Can you open it up and look for a missing tooth on one of the gears? That would give precisely the behavior you're talking about. Damage to gears is not uncommon, especially on servos attached to the nosewheel.

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Old 06-10-2018, 10:07 AM
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Regarding the AR636, HH search doesn't say anything about SAFE so I will try to make what I have work here.

Based on what you said to do, the receiver appears to be the problem.

Here's some pictures: first pic: where the servo arms end up after startup w/ throttle application, second pic is rudder position. After picking up the airplane and introducing some intentional movement (yaw, pitch, & roll [wing installed] shows counter-actions taking place), third pic shows servo arm positions, and forth shows rudder position. Last picture shows rudder servo hooked up to servo driver using 6v with no evidence of drifting - tape marked with Sharpie to index servo arm center point. I can't reproduce the extreme deflection I've seen other times like I saw at the flying field. I'm slightly paranoid that the computer hackers are conspiring to make life miserable for us, using our PI to introduce bugs in the devices we use these days, watching our every move by satellites, devices, and smart phones and pointing and laughing at us...

What I do know is that the rudder servo always drifts to the left when hooked up to the rx. I don't think this situation threatens the life of the airplane - its just not ideal. If the drifting continues to only change a few degrees during a typical 10 minute flight, thinking about splitting the difference by setting up prior to flight favoring a little right rudder - as the flight progresses, it would improve as the rudder approached center and if it went to a few degrees left - no big deal.

However - thinking out loud here - if the system continues to migrate left, continuous repositioning of the output arm/adjustment of clevis is finite and becomes another problem.

On a better note, I had a chance to fly a club member's little Apprentice last Friday evening and was equally impressed at how great it flies - as well as it's bigger brother. Only caveat was that I couldn't trim out a tendency to turn right with application of left trim on his DX18 - both rudder and aileron. Not sure if stock setup but rudder was coupled to his aileron stick.






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Old 06-10-2018, 10:35 AM
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You can put SAFE into an AR636 if you install the version 2 code on the website and configure it using the new PC app. Details are in https://www.rcgroups.com/forums/show...-another-plane

Rudder and aileron shouldn't be mixed in the transmitter.

I too love the Mini Apprentice. I've bought several of them for friends and family and always been happy. I even used the guts in a seaplane design, just moved everything over. The AR636 is much better than the EFL receiver.

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Old 06-10-2018, 10:37 AM
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Doh, I was still typing while you posted.

Yep, supposing we do that now with sub-trim.

The drift is seemingly not a constant and occurs so slow (like trying to watch grass grow) that I wonder - I will do that though and possibly substitute some other analog servo I have lying around to see what happens if that's compatible with SAFE/AS3X.
Just for the record, the servo didn't budge from position when hooked up to the driver and left for 15~20 minutes but perhaps because there was nothing to excite it like when active under AS3X...

BTW, not that it necessarily means its still okay but I just exercised the rudder servo manually, full throw, by hand and felt no inconsistency or roughness in the gear train.

Thanks very much for your time on this issue; your help, experience, and expertise are greatly appreciated.

Last edited by H5606; 06-10-2018 at 12:27 PM. Reason: Additional info
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Old 06-17-2018, 01:48 PM
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After startup and throttle application, saw typical excessive deflection, reset rudder servo arm two splines forward to "over-center" rudder - favoring a little right, flew the airplane for several minutes and noticed a tendency to turn left, landed and saw usual left rudder/nose gear indication.

Decided the airplane can't continue to be flown this way - especially for instruction - so set about removal and inspection of the rudder servo gear train as suggested.

A pallet knife slid only deep enough along the servo cavity to cut through the RTV and free up the sides of the servo, then using a small pry bar to lift, not pry the servo up out of the cavity resulted in a nice, clean extraction. The RTV-like adhesive smells like Chinese model aviation; using an X-Acto blade to slice the adhesive at the corners permits access to the screws on the servo case. Inspection of the gear train showed no broken teeth that I could find.

I'm going to try flying the airplane with a Hitec standard HS-422 substitute that fits the existing cavity well and appears at cursory inspection to be more stable so far.








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Old 07-01-2018, 07:24 AM
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Recently, went to set up this Hitec servo with an output arm matching hole spacing of OEM rudder servo and discovered I had left battery #2 connected... for about a week. Since I'm unaccustomed to the extra step of dealing with a master switch on the side of the fuse for electrics, human error prevailed. Brand new $50 battery pack. Charged once. Never flown. The switch was off. Let's try it. Nothing. Uh-oh. Dead. Really? Individual cell checker doesn't even light up. Try charging. Charger reads low voltage error. Yes - dead. OMG NO.

Don't advocate doing this but decided to take the risk - checked on-line for similar circumstance and found a possibility - set charger up on NiCad and charged at .1 amp until battery read somewhere over 10 volts and individual cells held above 3V. Stayed with the battery whole time and periodically felt for warmth - it stayed cool. Cool. Switched over to Lipo and charged normally in the sack.

Yesterday evening, put in three, back-to-back 9-minute flights with three separate batteries and found rudder to be holding proper position. Sroblem polved? Rudder servo all along? Possibly? Probably? I dunno. I've made claims before and end up being bit down the road. Optimistic that successive flights will be free of this rudder problem from here on out. Thanks for watching and thanks again for your help.

Note: this servo substitution required switching to reverse at the Tx.


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Old 07-01-2018, 08:22 AM
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I've used that technique to revive a discharged LiPo before, it works but you must be careful and try several times as the process moves along to get the charger to pick it up properly and switch to LiPo charge regime as soon as it will do it
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Old 07-01-2018, 10:10 AM
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Originally Posted by BarracudaHockey View Post
I've used that technique to revive a discharged LiPo before, it works but you must be careful and try several times as the process moves along to get the charger to pick it up properly and switch to LiPo charge regime as soon as it will do it
Noticed the middle cell was slightly trailing the other two (by couple tenths) during the revival process but hope it will be alright. Did stop revival couple times to check cells individually. It looked better during normal charge but maybe this is a false indicator of cell health. Your comment got me to check just now out of curiosity. Battery #2 reads 3.88; 3.86; 3.89; all at 11.6V. Hoping three-hundredths is considered negligible.

The other two batteries are showing 11.7V with cells in closer match.
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Old 07-01-2018, 10:25 AM
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if you have a good charger it should take care of it on the top end of the charge
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Old 07-01-2018, 10:36 AM
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Don't know if considered good - probably weak for the higher cell counts (above 3 cells?) - its a couple year old, Hitec (4 port) Multi X4 AC Plus.
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