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Crashed

Old 12-21-2014, 09:19 AM
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Malapp1
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Two days ago, I had a mid air with another plane. My 70" Revolver wing panel was almost cut in two but, I landed safely. I had the same wing panel that I fished out of the crash box long ago. I installed a new Specktrum servo and went back to fly. As soon as I lifted off and started the climb, the airplane went into a roll that I could not stop. It just rolled all the way to the ground. There was no apparent reason for the roll, it was like it had locked ailerons in the left position and they would no release. After I pulled all the gear out before putting it in the crash box, I realized that I had inadvertently installed a Hightek servo in the previously broken wing. spectrum on the right and Hitek on the left with a JR XG 8 transmitter. Any ideas if this mismatch would cause the locked ailerons?
Old 12-21-2014, 12:44 PM
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rmh
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did both servos rotate in same direction?
Old 12-21-2014, 01:02 PM
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Malapp1
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No, I doubt that. Both in the same direction would probably resulted in some form of loop.
Old 12-21-2014, 01:50 PM
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Aileron servos darned well better be rotating in the same direction since the linkages are always setup in a mirror image!
Did you confirm that the ailerons were operating correctly after replacing the servo?
Also, are the two servos on a Y harness, or on separate channels on the receiver?
Pete
Old 12-21-2014, 01:57 PM
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JohnBuckner
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Yes having an aileron servos functioning 180 degrees apart could very easily get you into a grave yard spiral faster than I can type It. Its for times like these that I cannot express enough the importance of a preflight control direction test. Each one individually and for proper direction Just before every single flight.

John
Old 12-21-2014, 05:29 PM
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Malapp1
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Yes, pre flight was perfectly fine. No directional issues and linkages were fine. It was after lift off and very weird. Just started rolling and wouldn't stoo.
Old 12-21-2014, 05:45 PM
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JohnBuckner
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OK this is the way I make every last direction just seconds before flight. First I always stand directly behind the airplane (never in front of it) then I call out loudly so anyone around can hear "LEFT" then I give it full left rudder and hold it now it is at this time I say cool that little flap goes up and make this wing go down now still holding full left I look at the aileron on the right side of the airplane and if I cannot say cool that little flap goes down and makes this wing go up, then there is a problem.


If you are not doing this then you have not made a control direction test.

John
Old 12-21-2014, 07:15 PM
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woodie
 
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Did you have any other control like throttle, elev or rudder? How is your failsafe set?

Woodie
Old 12-21-2014, 07:28 PM
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The description of your crash and the radio caught my attention.

If you have dual elevators operated by separated channels that are married together in the wing configuration screen... check that they are operating normally?

Here is what happened to me with my XG-8. The plane suddenly went into a roll and but I had some control but could not regain normal level flight or hold altitude so I cut the power and let it come down trying to level the wings as best as I could. It hit hard on the front section and cartwheeled. It wasn't until after the rebuild was nearly finished that the cause was discovered. After rebuilding the whole front section, the radio was fired up to install the choke and throttle linkage. I'd forgotten what the choke had been assigned to and hit the gear switch... the choke servo didn't move, but something was.

The plane had removable stabs that had been removed during the rebuild and thus it wasn't readily apparent what was moving, and in a few moments I realized that the gear switch was moving the elevator servos. In Pos 0, they would go hard over in opposite directions, in Pos 1, the were neutral and functioned nominally, in Pos 2, they again went hard over in opposite directions but opposite to the directions they did in Pos 0.

What the hey.... the elevators are not supposed to respond to the gear switch and it suddenly hit me that I now knew the cause of the crash. I searched for some reason, a mix or anything that would explain what was happening.... and found nothing. There were no mixes. The only explanation seemed to be that the gear ch was mated to the elevator ch for the dual elevators.... but doing so is a perfectly normal setup and even illustrated in the manual. The plane had flown seven months thus configured and I had another plane that had flown a year configured the exact same way and the gear switch had no influence upon the elevators.

Finally, the gear ch was unmated and when doing so, the gear switch then controlled the left elevator only and had no influence over the right elevator. In short, all was now operating nominally again. At that point, the gear ch was again mated to the elevator and all was nominal, with no influence from the gear switch.

I called Horizon, and as expected, they offered that they couldn't fix a problem that couldn't be repeated and suggested I upgrade to the latest software version. I did and also traded the elevator slave fro the Aux 2 and moved the choke to the gear ch. Ive had no other problems with the radio.

Elevators suddenly going full over in opposite directions will induce a roll and squirrel up pitch control. Let us know what you find.

btw.... this wasn't a problem that existed before the flight began, it suddenly happened about eight minutes into the flight.

btw #2... if it in fact is what happened to yours, do not unlink the mating of the elevators until after you have saved the model info to the SD card as otherwise you will be in the same boat that I was... having no way to prove it was a software glitch.

Last edited by AA5BY; 12-21-2014 at 07:43 PM.
Old 12-21-2014, 08:18 PM
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Malapp1
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I appreciate your input. The only configuration that changed was the aileron servo but, I do recall having to reverse the flaperons when I got tot the field. I was really nervous about the radio and found out today that it was an open box deal. So, after talking with the LHB, he agreed to return the radio I exchanged the radio for a DX9 Black addition. I have had a SebArt Miss Wind all ready to go. I guess we will never know what caused that crash. I had many flights on the Revolver and it could have been something I missed after the mid air. I just don't know.
Old 12-21-2014, 11:14 PM
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Larry882
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Where you using a genuine JR (Y) cord? For some reason I have seen 2 instances of the Y cords with a Choke in the heat shrink tubing fail and cause one of the servos to go to an extreme postion and lock up in that position. Happened to me in my 1/4 scale cub but I caught it on the ground.
Larry Kopecky
Conyers, Georgia
Old 12-21-2014, 11:40 PM
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drac1
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I have had Hitec servos, (on ailerons only), do the same thing when all other servos were JR.
Old 12-22-2014, 08:56 AM
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flycatch
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It appears that the majority of the posters are blaming the operator. I have had two Hitec servos' fail on the bench and they both slewed 180 degrees when under power. When I contacted Hitec they asked me for the model number and then asked at what voltage I was using to run them. I told them 6V and they say they were rated at 4.8V and that caused the malfunction.
Old 12-22-2014, 09:02 AM
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Truckracer
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How about the servo arms? Did you use a Spek / JR arm on that Hitec servo? Slipping could cause your issue.
Old 12-22-2014, 04:15 PM
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maybe damaged servo from midair?
Old 12-22-2014, 04:19 PM
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Originally Posted by JohnBuckner View Post
OK this is the way I make every last direction just seconds before flight. First I always stand directly behind the airplane (never in front of it) then I call out loudly so anyone around can hear "LEFT" then I give it full left rudder and hold it now it is at this time I say cool that little flap goes up and make this wing go down now still holding full left I look at the aileron on the right side of the airplane and if I cannot say cool that little flap goes down and makes this wing go up, then there is a problem.


If you are not doing this then you have not made a control direction test.

John
Confused me here.... you give a rudder command and look to see if the ailerons are moving?
Old 12-22-2014, 04:22 PM
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Malapp1
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Yes all cords were JR
Old 12-22-2014, 04:24 PM
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Malapp1
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i am so afraid of the HiTec servos that I took all of them out of my Miss Wind and replaced them all with Spektrums
Old 12-22-2014, 04:27 PM
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Malapp1
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Nope correct arms on both.
Old 12-22-2014, 04:28 PM
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Malapp1
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Not likely. The other wing was not damaged at all.
Old 12-22-2014, 04:51 PM
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drac1
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Originally Posted by Malapp1 View Post
Not likely. The other wing was not damaged at all.
Still could have damaged the servo though. May have broke a tooth off one of the gears?

The problem I had was mixing Hitec servos with JR. I know many do mix brands, but I think it is better to have all the same make.
Old 12-22-2014, 04:54 PM
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drac1
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Originally Posted by pkoury View Post
Confused me here.... you give a rudder command and look to see if the ailerons are moving?
Yes, that had me thinking too. Accident waiting to happen.
Old 12-22-2014, 06:17 PM
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Malapp1
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I am starting to think that it was a voltage problem. The HiTec is probably a lower voltage than the Spektrum. I have to check that out.
Old 12-22-2014, 09:23 PM
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Originally Posted by Malapp1 View Post
I am starting to think that it was a voltage problem. The HiTec is probably a lower voltage than the Spektrum. I have to check that out.
http://hitecrcd.com/faqs/servos/general-servos

A. All Hitec servos can be operated within a 4.8 - 6V (4 or 5 cells) range. Only the HS-50 operates exclusively at 4.8 volts (4 cells).
Old 12-22-2014, 09:28 PM
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I use mostly Hitec servos in all of my planes. ALL planes set up with LIFE 6.6 V, unregulated. From $10 servos to $150 servos. Never a problem. I've never heard of hitec servos that had to be at 4.8V. In fact, I've never had a 4.8V system.

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