Need help with elevator issue (SAFE) on UMX Turbo Timber

[davidrinnan]

I bought a umx turbo timber and have had lots of fun with it. Flies very nice. I "dropped" it in the water (...). Had no way to fix it at the summer house so I bought a new one. Currently both are flying but the old one has a disconnected Flap servo.

Anyways the new plane out of the box had an issue where it is aiming down with SAFE ON. I could handle it and trimmed it out on the transmitter to allow me to fly the maiden. When I landed after the short flight I put it back in normal mode SAFE OFF, as always before taking out the battery since this takes all control surfaces back to their current zero position as they are electronically and mechanically trimmed.

I reset my digital trims to 0 and began adjusting the elevator mechanically, but I noticed it was pretty perfectly aligned. So I began switching between SAFE on and off on dry land on a flat surface and noticed that once I turned SAFE on the elevator points down. My experience from other SAFE planes is the opposite actually. Safe on usually give you a little bit of elevator up.

If I mechanically trim the airplane to fly straight with SAFE ON it will almost stall if I then turn SAFE OFF.

I can basically not find a mechanically trimmed setting where the airplane will be able to fly straight with SAFE on and off.

What I have done now is to mechanically trim the elevator to fly straight with SAFE and if I turn SAFE OFF when flying I have to max out the elevator DOWN trim on the transmitter in order to be able to fly.

It is easy to see the pretty big difference in elevator position when switching SAFE on and off when on a flat surface. It is too big to be able to find a good in-between middle ground.

I have no clue what to do to fix this problem. I have tried my old umx turbo timber and it flies perfectly without these issues, just a slight favour to go a little up with SAFE on.

I have a DX9 transmitter. I don't have the slats installed. Everything is stock apart from the batteries where I use a 500mah.

 

[OlliePackman]

I bought a umx turbo timber and have had lots of fun with it. Flies very nice. I "dropped" it in the water (...). Had no way to fix it at the summer house so I bought a new one. Currently both are flying but the old one has a disconnected Flap servo.

Anyways the new plane out of the box had an issue where it is aiming down with SAFE ON. I could handle it and trimmed it out on the transmitter to allow me to fly the maiden. When I landed after the short flight I put it back in normal mode SAFE OFF, as always before taking out the battery since this takes all control surfaces back to their current zero position as they are electronically and mechanically trimmed.

I reset my digital trims to 0 and began adjusting the elevator mechanically, but I noticed it was pretty perfectly aligned. So I began switching between SAFE on and off on dry land on a flat surface and noticed that once I turned SAFE on the elevator points down. My experience from other SAFE planes is the opposite actually. Safe on usually give you a little bit of elevator up.

If I mechanically trim the airplane to fly straight with SAFE ON it will almost stall if I then turn SAFE OFF.

I can basically not find a mechanically trimmed setting where the airplane will be able to fly straight with SAFE on and off.

What I have done now is to mechanically trim the elevator to fly straight with SAFE and if I turn SAFE OFF when flying I have to max out the elevator DOWN trim on the transmitter in order to be able to fly.

It is easy to see the pretty big difference in elevator position when switching SAFE on and off when on a flat surface. It is too big to be able to find a good in-between middle ground.

I have no clue what to do to fix this problem. I have tried my old umx turbo timber and it flies perfectly without these issues, just a slight favour to go a little up with SAFE on.

I have a DX9 transmitter. I don't have the slats installed. Everything is stock apart from the batteries where I use a 500mah.

Safe is a nightmare and you will never be able to actually alter the safe settings because it is on the receiver unless you can re program it on a computer but don't go down that route. I would suggest accepting the fact that this will always happen when turning safe on and off but then to combat this, set up some dual rates. Program the dual rates on your transmitter so that dual rates off and safe on gives you stable flight with no issues and then program the dual rates to add a few clicks of up elevator when dual rates is on. Then set the dual rates button to the same button that turns safe on and off so that you only have to flick one switch and it will automatically combat the safe malfunction. Make sense?

 

[davidrinnan]

Yeah that could be a way around it I guess. But it seems so strange. I have sport cub s2 and another turbo timber umx which work very great with safe. Today I tried to disengage SAFE altogether and then reconnect it but not working. Same issue.

I have also tried to balance the plane differently when connecting the battery but it doesn't seem to make a difference. It is even so that if I tilt the plane too much when connecting the battery it won't complete the "connection" procedure, until I bring the plane more level.

it is as if the idea of "level" is pre-programmed and it seems extremely stupid to do so and set it at a erroneous value at the factory without the means to change it.

 

[cwood]

I, like you now have two UMX turbo's....the first one was so much fun (also around water on the weekends) that I bought another just in case because they were low in stock in Canada. I have not maidened the new one yet (its so pretty compared to my Gorilla blue blotched, battle worn one) but I never both with Safe mode. Why do you want to use it? I can try switching in flight next time I run it and see what happens...I have not switched in flight but do have it on a switch.

 

[davidrinnan]

On my old plane and on my sport cub s2 it works fine to go between safe and normal. That is the intention behind the developers. I have not flown 4channel planes long enough to be able to fly confidently without safe, especially since my whole flying area, at the summer house, is over water

Usually there is a small change in elevation when going from safe to normal, since the plane masques poor trimming/CG, assuming the safe chip is working correctly.

 

[OlliePackman]

Yeah that could be a way around it I guess. But it seems so strange. I have sport cub s2 and another turbo timber umx which work very great with safe. Today I tried to disengage SAFE altogether and then reconnect it but not working. Same issue.

I have also tried to balance the plane differently when connecting the battery but it doesn't seem to make a difference. It is even so that if I tilt the plane too much when connecting the battery it won't complete the "connection" procedure, until I bring the plane more level.

it is as if the idea of "level" is pre-programmed and it seems extremely stupid to do so and set it at a erroneous value at the factory without the means to change it.

Yeah safe has a sort of idea of what level is and that is fine tuned when you connect the battery. There is however no way of adjusting this because it is already programmed into the receiver but its programmed wrong. You have just got a defective one. Email the company and they might refund you for that part.

 

[Bricks]

You do not have a mix turned on in your DX9 by mistake? I would start from scratch with a new model and see what happens.

 

[davidrinnan]

I have not set up mixes and have not investigated that much on that business-end given that I can fly my other turbo timber UMX with the same model/settings without any issue whatsoever. But I will try a new model anyways just to make sure and really start everything from scratch!

 

[davidrinnan]

I have tested some more, with my two umx turbo timbers. The old one, with safe/asx3 engaged by increasing the throttle, standing next to each other on the table, the old one adjusts the elevator upwards very slightly, lets say 1-2mm whereas the new one adjusts aggressively about 10mm. I have to points the airplane down about 20 degrees before I get a level elevator.

It is so strange that I can trick the SAFE by mechanically adjusting the elevator to get a smoother ride. This indicates to me that maybe the servo is faulty in some way? I don't know, I just know to little on the exact tech behind this to solve it.

 

[OlliePackman]

I have tested some more, with my two umx turbo timbers. The old one, with safe/asx3 engaged by increasing the throttle, standing next to each other on the table, the old one adjusts the elevator upwards very slightly, lets say 1-2mm whereas the new one adjusts aggressively about 10mm. I have to points the airplane down about 20 degrees before I get a level elevator.

It is so strange that I can trick the SAFE by mechanically adjusting the elevator to get a smoother ride. This indicates to me that maybe the servo is faulty in some way? I don't know, I just know to little on the exact tech behind this to solve it.

I doubt its the servo because it works fine when safe is off and only malfunctions when safe is engaged so it's almost definitely the safe system. Try swapping the receivers from each plane and see if it solves the problem. Then maybe rebind to the faulty one?

 

[Bricks]

Check your screens for servo setup and compare between the 2 planes, check how each is setup and see if there may be a difference.

 

[davidrinnan]

the new plane, since it is the same make/modell is just a copy of the old model in the transmitter so they are running the exact same settings.

 

[Bricks]

the new plane, since it is the same make/modell is just a copy of the old model in the transmitter so they are running the exact same settings.

Did you check maybe when the copy was used something did not transfer.

 

[davidrinnan]

For the sake of others finding this when searching. I have officially given up and will try to return the plane, since it is new.

If it was old I would take it apart and:
1. try to see if repositioning the AS3X unit could help
2. get cables needed to reprogram the AS3X chip

Things I think I have learned in the process of trying to fix the issue.
a) Most people have sometime noticed how well SAFE will masque incorrect mechanical trim. Everything is going along well and you turn off SAFE just to notice that the plane is very poorly trimmed. For the same reason, trying to fix bad SAFE flight characteristics will most often not work by means of adjusting the mechanical trim since the gyro, let's say it is positioned wrong, will just compensate based on it's own understanding of what is level.
b) Flight modes are very powerful, once you understand that you go into the trim settings and define which channels should be "common" (i'd call it global) and which channels are flight mode specific. This makes it possible to put a flight mode on the same switch as safe and digitally compensate (yes digital trim compensation seem to work somewhat, compared to mechanical) the safe mode, or the normal mode.
c) if you have flaps, like UMX timber, SAFE automatically adjust down elevator, especially in the take off flap position. If you after having solved your issue with "B" above, you will now understand that if you want to fly with flaps without safe, you want to have your own down elevator adjustment and that will increase the issue with SAFE, if you already have a down-striving safe plane.
d) tilting the plane slightly up or down when inserting the battery does not seem to have any effect. As a matter of fact, tilting it too much will not allow the plane to startup/bind properly.
e) SAFE is very dependent on a properly programmed (simple) and aligned (not simple) gyro. Putting a product like that on the market without providing means of simple re-calibration must have led to, thousands of crashes, thousands of returns, thousands of clients who think SAFE is crap or who even consider e-flite crap. Just because they have gotten a poorly configured AS3X receiver.
e.2) I understand that this might sound simpler than in is. Since most people never read a the manual, what if the AS3X chip reconfigured when putting the battery in, it could lead to disaster. This means that there has to be some sort of new protocol, similar to turning SAFE on/off entirely by putting the levers to the down/side and flipping a switch five times. etc etc.
f) when I talk to people about my SAFE diving, some people say their SAFE is climbing, others are saying that their SAFE is also diving but just very slightly. It seems to me that this must be a positioning quality issue. (hence the need for re-calibration)
g) my other SAFE planes have a slight tendency to climb when in safe, which for me sounds reasonable and part of the programming, if such programming exists.
h) It is possible to define a mix where, for example, the left trim knob can be used to trim the elevator when flaps are in position 1, and another mix when flaps are in position 2. This can then be reviewed post flight and entered into the flap settings. You would then put both LT and RT to zero and could keep them there are fine adjustment later on. Or remove entirely.
i) when contacting support at e-flite. Don't mentioned where you have bought the product, unless asked for (of course). I happened to mention I bought it at a swedish retailer whereby their immediate, and only, response was to talk to my local retailer. Given that I don't have that much of a problem understanding or making me understod in english - i'd hoped to be able to actually get some support. Or maybe they were just going to say, here is a new plane, and I understand they cannot do that and ship overseas.
j) contacting e-flite support by means of their form will actually only create a ticket so that you can then, by answering the automatic email you get as a reply, provide your actual support information. I was waiting for 8 days with nothing but the first auto email until I understood this fact. Once I replied to the email I got an answer the same day. Or.. maybe they just answered quick because they saw an opportunity to write it off directly since I mentioned I bought the plane in Sweden.

What I haven't learned in the process
*) I am actually uncertain about point C above. I.e. if I am running with takeoff flaps in safe I know that SAFE provide down elevator even if my transmitter flap setting has a value of 0%. So what actually happen if I have lets say 10% in my transmitter.
**) Given that we are suposed to fly these planes we know very little about the details of AS3X and SAFE. There are some many different views out there on how it works. Like "lift the tail when booting up etc". A long list can be made.. Anyways, we are suposed to search for bugs in stuff we don't have the specifications for. For instance, the effect of digital trim on SAFE.
***) Digital trim on safe is actually very interesting. If you have a safe that is working bad, solving it with digital trim, preferably as per point B above, is not affecting the travel of the servo. Compared to digitally having to trim a poorly mechanically trimmed servo. The latter will affect the travel but the digital trim on the servo with safe will not. You are as I experience it, simply telling safe to adjust what it consider as being the current sought after position. I may be wrong.

 

[Bricks]

If you want to fix your receiver you can reprogram many of the AS3X receivers you would need a dongle, it is really not that hard and with your DX9 you can make adjustments thru the transmitter with the latest update.

https://www.rcgroups.com/forums/showthread.php?2135213-Eflite-SAFE-RX-in-another-plane