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Old Apr 16, 2012, 03:58 PM
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idletime's Avatar
Canada, ON, Toronto
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Originally Posted by RoboSerg View Post
After one severe crash my AXN doesnt glide It flies with throttle, but as soon as I drop the throttle to glide the plane looses its speed and then the nose does a 90 turn to the ground and the plane just falls face planting the ground. During falling its also uncontrollable. Anyone had this? I tired repairing the plane, its the fourth time already, I repair it, go to the field and the plane just falls like a stone to the ground as soon as I kill the throttle
I presume you have already checked the location of the battery for CG, cuz it sounds like the battery is now to far forward. This just off the top of my head.
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Old Apr 16, 2012, 04:00 PM
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Originally Posted by idletime View Post
I presume you have already checked the location of the battery for CG, cuz it sounds like the battery is now to far forward. This just off the top of my head.
Yep, that's what I also thought. I even replaced the aileron servos to exclude the possibility of bad servos. I always check the CG after each repair and I check right underneath the wing spar. Seems OK every time.
Overall the plane is unflyable right now, or better to say uncontrollable when gliding. I crash it after 1-3 min of flight and go home to repair. For the 4th or 5th time in a row already I was filming today but it was not so clear on the camera. Will try to catch a good shot of the planes behavior.
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Old Apr 16, 2012, 05:09 PM
More coffee, please!
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Austria, Wien, Vienna
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Ow, that sounds bad!

The moment you kill the throttle it just dives and is not under control? Even if you give it a full upper elevator?

Compared to a rock: does it fall faster (i.e. does the horizontal speed component bleed off at once), the same (ballistic), or slower (meaning still gliding "a little bit")? Direct dive or spiraling?

Maybe a stupid question, but do you have any strange/extravagant throttle / elevator mix programmed? When it "lands" now, what is the position of control surfaces? Could it be that the TX or RX have developed some kind of a problem?

Maybe you could power it up, hold it in your hand, move the sticks around while giving throttle (not for too long, 4-5 seconds max), then killing throttle and looking what happens.

Oh, what about the safe mode? Maybe it loses the connection when the throttle goes to 0 and the safe mode is set "full elevator down"? (or something similar). The more I think about it, the more likely this theory sounds to me, that would also explain why you have no control over it once it starts the dive. After the crash, do the servos move when you move the sticks, or do you need to power down / up the system in order to get the connection back?

I suppose you have already checked the inclination of the horizontal stabilizer? When you put a long ruler flat on it, it should end pretty much at the nose of the plane. However, that would also make itself noticeable while you fly under power.
Other than that... no idea.
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Old Apr 16, 2012, 05:27 PM
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Just thought of something.....if your plane components are no longer in their original positions, when the elevaton are in netural position, they may actually be in negative effective position.

This can happen for example if the tail boom is re-glued and not aligned property with the main fuslage.
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Old Apr 16, 2012, 06:03 PM
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Yep, the plane just dives goes into a spiral with no way to recover.
The TX is in the car now but I think I don't have any throttle mixes, any mixes at all (to exclude it from the equation).
The TX / RX was loosing range couple of weeks ago, fixed itself somehow. Maybe the TX module didnt have the contact to the TX.
Will try to hold in the hand and see how it behaves tomorrow.
Dont have any safe mode, RX doesn't support it.
The horizontal stabilizer seems horizontal

Quote:
Originally Posted by idletime View Post
Just thought of something.....if your plane components are no longer in their original positions, when the elevaton are in netural position, they may actually be in negative effective position.
This can happen for example if the tail boom is re-glued and not aligned property with the main fuslage.
Yeah, I constantly glue the tail back in =) But it would be noticeable during flying with throttle wouldn't it ? Also some trim would fix it also, right?

Check out the video of today's two crashes. Will do more videos tomorrow:
Weird AXN Clouds Fly problem + crash (turns out being tail heavy) (1 min 44 sec)
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Old Apr 16, 2012, 06:12 PM
More coffee, please!
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Austria, Wien, Vienna
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hmmm.. spooky, really!

I don't get how it can fly normally while under power and then go havoc like that when you take the power away! I mean, without a rudder (taped in), the maneuvers in your video seem to be hard to reproduce even on purpose.

those lights, where are they connected? to the rx out (5V) or directly to the lipo with a voltage regulator?
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Old Apr 16, 2012, 06:17 PM
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Originally Posted by sir_clive View Post
hmmm.. spooky, really!

I don't get how it can fly normally while under power and then go havoc like that when you take the power away! I mean, without a rudder (taped in), the maneuvers in your video seem to be hard to reproduce even on purpose.

those lights, where are they connected? to the rx out (5V) or directly to the lipo with a voltage regulator?
The lights are connected to the battery w/o any voltage regulator because the lights are suited for 7-12 volts.

Haha, now imagine that SAME behavior happens 4-5 times in the row resulting in crashing Are you agree that even the wrong CG would not cause that behavior ?
I will go try to fly tommorow and show the plane in all detail's. I am running out of options of probable causes

Gre aus Deutschland
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Old Apr 16, 2012, 06:19 PM
Aus
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Quote:
Originally Posted by RoboSerg View Post
Yep, the plane just dives goes into a spiral with no way to recover.
The TX is in the car now but I think I don't have any throttle mixes, any mixes at all (to exclude it from the equation).
The TX / RX was loosing range couple of weeks ago, fixed itself somehow. Maybe the TX module didnt have the contact to the TX.
Will try to hold in the hand and see how it behaves tomorrow.
Dont have any safe mode, RX doesn't support it.
The horizontal stabilizer seems horizontal



Yeah, I constantly glue the tail back in =) But it would be noticeable during flying with throttle wouldn't it ? Also some trim would fix it also, right?

Check out the video of today's two crashes. Will do more videos tomorrow:
http://www.youtube.com/watch?v=oDfXApJADrw
It's hard to be 100% sure from the video but your motor mount appears to be off to the side. When you launch it side slips through the air. It is possible that you are flying (or trimming) the model to compensate for this thrust line and when you power off it wants to take on it's natural gliding line which is far different to the power line which you are flying.

Try an unpowered launch (glide) and see what it does. Trim this and then compare it to the powered flight trim and see how much difference there is.
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Old Apr 16, 2012, 06:20 PM
More coffee, please!
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something more, that motor mount seems to be under a strange twisted angle. was that a result of the last crash, or is it like that all the time? or is it just an illusion on the video?

just prior to the crash, the motor was running on what seemed to be a high rate. was it you pushing the throttle, or was the stick in zero position?
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Old Apr 16, 2012, 06:23 PM
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Quote:
Originally Posted by sir_clive View Post
something more, that motor mount seems to be under a strange twisted angle. was that a result of the last crash, or is it like that all the time? or is it just an illusion on the video?

just prior to the crash, the motor was running on what seemed to be a high rate. was it you pushing the throttle, or was the stick in zero position?
The motor mount broke during crashing. Happens all the time now. I glue the motor mount back in for the 4th time already Will show the plane in all details for you tomorrow.
Just before the crash first crash I tried to recover with some throttle. I think the second crash was with 0% throttle.
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Old Apr 16, 2012, 06:27 PM
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Quote:
Originally Posted by RoboSerg View Post
Yep, the plane just dives goes into a spiral with no way to recover.<snip>
You have the classic tail heavy airplane. Fix the CG and check all of your surfaces after those nose-ins.
AJ
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Old Apr 16, 2012, 06:28 PM
More coffee, please!
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Austria, Wien, Vienna
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ok, looking forward to those pics. what Aus said really sounds like a good idea, I noticed the angle but I overlooked that side slip after the launch.

Gruesse zurueck aus Wien!
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Old Apr 16, 2012, 06:30 PM
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Originally Posted by ajbaker View Post
You have the classic tail heavy airplane. Fix the CG and check all of your surfaces after those nose-ins.
AJ
Yes, after today's repair it was really tail heavy, as I put some dead weight on the tail after last repair, where I added some glue to the nose.
Would a tail heavy plane have exact my behavior? Nose diving 90 degree to the ground w/o a chance to recover? Thats the main question for me.
Also just to be sure, the CG on AXN is under the wing spars or 49-55mm from the leading edge, right? Plus / minus 5mm is OK, apparently?
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Old Apr 16, 2012, 06:49 PM
Just thumbing through...
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United States, SC, Simpsonville
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I agree it looks like a stall, probably tail heavy. The warped wing looks like it would act like flaps, slowing the plane, it then tip stalls.
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Old Apr 16, 2012, 06:59 PM
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Canada, ON, Toronto
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I got the solution......buy a new one lol.

Sorry, couldn't help it.

$35 http://www.hobbyking.com/hobbyking/s...dProduct=16569

The reason I saying this is I have an older AXN that flys wonky - no where as wonky as yours - but I just gave up and bought a new one....much easier and quicker that 'figuring it out'.

EDIT: In all seriousness...I would love to know the cause of the why your plane is flying the way it does. If you do 'figure it out'...please share
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