Lumenier RB2205C-12 2400KV SKITZO Ceramic Bearing Motor
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Old Sep 26, 2004, 10:31 AM
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Plane all outta whack!!!


I've been flying my SIG Somethin' Extra for a season and a half now. It has been a real pleasure flying it.

But, today I took it to the field taxiid out, and put it into rotation.

It immediately climbed straight up, rolling severely to the right, and yawing very badly.

Really shook me up. I did get it trimmed out, and brought it in for a landing. The trims were moved to almost the extreme!!

I use a Futaba T6XA, and it has programmable trim memory. Did the trim memory get lost?? That's the only thing I can think of.

The plane has about 150 or so flights, and this has never happened before.

Any ideas what may have happened??

Viper Pilot
Last edited by Viper Pilot; Sep 27, 2004 at 11:16 AM.
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Old Sep 26, 2004, 10:50 AM
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I have same radio, but newer had such situation. but are u sure that there was no kid or ypur enemy with your tx? I had such situation, that someone swithed reverse on my tx. but it was without crash. how old is your futaba? and by the way if other memory settings are ok, then u must think that someone made changes in tx.
Old Sep 26, 2004, 10:55 AM
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I was at the field all by myself!! I did a pre=-flight check and everything seemed just fine. I even turned off my rx and tx after the flight and turned the rx back on to see if I got "hit" by some park-flyer, but all was well.
Old Sep 26, 2004, 12:13 PM
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soooo. that's interesting.
Old Sep 27, 2004, 07:19 AM
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Do you use the same transmitter for other planes?

I'm just trying to help you pinpoint the trouble.
Old Sep 27, 2004, 11:18 AM
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Yes, Greg,

The transmitter is a 3-model and I have a Spacewalker and a Diamona (elevon, kinda wing-thing). I took the Spacewalker out yesterday afternoon, and it flew just fine.

This even confuses me more.

Any ideas??

VP
Old Sep 28, 2004, 08:49 AM
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It sounds like it isn't the transmitter because it works fine with other models.

This points me to focus on your radio equipment in the plane itself.

The most common areas of failure in onboard radio is the switch. Next in line is servo failure. I've seen one bad servo make good ones act up.
Old Sep 28, 2004, 10:10 AM
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Greg,

This REALLY confuses the issue.

I used trim memory when I got the Somethin' Extra on the ground, and quit for the day. Last night I took it out to the field to give it a try again.

The trim was outta whack again, but in the opposite directions . . . . elevator way down, ailerons way to the left and rudder to the left.

I didn't take 'er up.

Seems to have "reversed" the trim memories, just like the trim memory was correct the day before.

So, Ive deleted memory for that model from the tx, readjusted the clevises, and will try to reprogram all today.

I've chjecked the crystal, and all the servos are plugged in and working fine (apparently).

I am really confused on this. Never happened before.

VP
Old Sep 28, 2004, 02:21 PM
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Have you been using a mobile phone close to the transmitter?

Those symptoms sound something like the ones described in anectdotal evidence over here for the past few years, attributed to resetting of model memory in computerised transmitters by emissions from mobile telephones.

There's a lot of debate about it, whether it's feasible or not, whether it's a problem or not and there is no concensus at present. However, erring on the side of caution, the advice we receive from our national body is not to use a cell phone next to a computer TX.

Here's a link

http://www.bmfa.org/news/bulletins/bull_mobiles.html

Hope you get your problem sorted out.

Brian
Old Sep 29, 2004, 11:02 AM
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Brian,

All I can say is "could be". I took the plane out today and gave it five short flights, and did clevis adjustments following each flight.

I now have the Sometin' Extra trimmed out mechanically, with no trim adjustment and will not be using trim memory on the plane.

It seems to be flying just fine. I guess that is the proper way to trim anyways . . . don't rely on technology, just get it flying straight and level mechanically.

Thanks to all for all the help. If anything wierd happens, I'll re-open this thread and get some more input.

Viper
Old Sep 29, 2004, 10:08 PM
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I'm just getting back into the hobby after 15 years away. We always trimed for the best mechanical adjustment and then used the trim tabs for the occasional in flight irregularity. Of course we did not have model memories and Digital computer radios except for very basic and very expensive ones.

Your goal should be to have each plane set up so that 0 trim on all tabs should provide a straight and level flight. The only exception is that the throttle tab can be set so that Mid to High trim is Idle and Low trim can cut the engine completely with the throttle pulled all the way back.
Old Sep 30, 2004, 08:35 AM
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Gotcha, John,

That's what I did.

VP
Old Sep 30, 2004, 08:52 AM
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I know you've sorted it for the moment, but I've just read this post and my initial reaction -- especially when you say things were back to normal the second time out -- is that the problem is mechanical.

Personally I would be checking out the pushrod ends to see if any of the clevises have partly stripped their threads. Under load they could 'jump' one or two threads in one direction one day, and then jump back again under an opposite load later. The load could be in the air, or a knock when loading and storing the model. I've had this happen once with metal clevises on metal pushrod ends -- when I looked closely I saw that the threads on the pushrods had been worn almost smooth by vibration and metal-to-metal contact. Ever since then I've used nylon clevises.
Old Sep 30, 2004, 12:14 PM
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abenn,
Flew the SE again last night, and it seems to be back to its sweet ol' self.

I've checked the pushrods pretty thouroughly, but will do another check this afternoon.

My clevises are plastic on threaded stock attached to nyrod pushrods. They are stiffened in several spots along the length.

If I have any new problems I will re-open this thread.

Thanx for all the suggestions.

VP
Old Sep 30, 2004, 07:08 PM
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I have had this problem with my Twist here lately. Its not as bad as you stated (close though) but it seems it needed trimming everytime I brought it out. After a little investigating I found that the wing dowls were a little sloppy in there holes. With this every time I bolted the wing on it would end up being "off" a little from the last time thus changing the trim. I dont know if this could be your situation but if the S.E. has wing dowls it would be worth checking out.


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