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Cessna out of control

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Cessna out of control

Old 04-12-2006, 09:42 PM
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RCHYFLYER
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Default Cessna out of control

Well it hasnt even seen its first flight and its a mess now! My TF Cessna went out of control sunday and cracked it up! I was in my yard taxing with it to check out the turning radius of the nose gear and all of a sudden it went wide open throttle the wing hit one of my vehicles tires and slamed it into my daughters car doing $400.00 in damage to it. I'm not sure what caused it and any thoughts on this would be great. In my yard is a power box that sends current to 3 houses one of which is mine when this happened my plane was over top or atleast around where all of the power cables tv and telephone wires run under ground. Do you think this may have caused the throttle to go full open? I took the plane back to the same spot and turned the electronics on but it didnt do it again?
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Old 04-12-2006, 09:59 PM
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Flyboy Dave
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Default RE: Cessna out of control

The dreaded "Glitch from Hell"....it might have been a neighbor somewhere, but
most likely it was an unknown glitch that you will never find. []

Bummer....I have a plane just like that.

FBD.
Old 04-12-2006, 10:01 PM
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Mike Baldwin
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Default RE: Cessna out of control

Sounds like interference from something. Anyone else in your area have RC stuff. Or a bad receiver. I had one go bad like that once. Sitting on the bench it would work fine, but when I started the motor and ran it for a while the virbrations would cause it to clitch at times, not all the time but all of a sudden. Any way I hope you can fix it so she will at least get to breath the air up there.
Old 04-12-2006, 10:05 PM
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RCHYFLYER
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Default RE: Cessna out of control

It has on board glow and at idle its on need seemed to be a problem could it have caused the interference?
Old 04-14-2006, 11:00 AM
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Deadeye
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Default RE: Cessna out of control

That really sucks about the 182. I'm about 5 hours of work away from my maiden. Mine has the RAM lights, NAV and landing. Mine glitched terribly with the NAV lights on. I switched it out for a PCM reciever and the glitching stopped. Mine also has on board glow - the Expert unit. I have experienced no glitching from that. Hope you get it repaired and figured out soon!
Old 04-14-2006, 12:35 PM
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Liberator
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Default RE: Cessna out of control

On board glow CAN cause problems. Best thing to have someone restrain it and do a range check with the motor running and off. If you see a big difference, then you may need to work out shielding or even go to a new glow driver.

Did you have the antenna fully extended when this happened?

Old 04-14-2006, 01:19 PM
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shakes268
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Default RE: Cessna out of control


ORIGINAL: Deadeye

That really sucks about the 182. I'm about 5 hours of work away from my maiden. Mine has the RAM lights, NAV and landing. Mine glitched terribly with the NAV lights on. I switched it out for a PCM reciever and the glitching stopped. Mine also has on board glow - the Expert unit. I have experienced no glitching from that. Hope you get it repaired and figured out soon!
That doesn't mean the interference has stopped! PCM masks the interference until there is too much to overcome, then it goes into fail safe lockout. All of that interference is still there and at any time it could cause your PCM receiver to go into lock out mode.

Best bet is to resolve the issue with a PPM receiver THEN go to PCM when you know you're glitch free. PCM is NOT a fix for glitches.
Old 04-14-2006, 04:30 PM
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Flak
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Default RE: Cessna out of control

RichFlyer,
Were your battreies fully charged? I always range check my planes before starting the engine, (even at home) to prevent unwanted SNAFU's. Good luck.

"Keep 'Em Flying!"
Flak
Old 04-14-2006, 09:09 PM
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Default RE: Cessna out of control

Antenna was full out and batteries charged. Range check I ALWAYS do. One thing I'm not going to do is bypass or forget the basics. We are talking about a plane that I have 2yrs of my time building and countless money in, the last thing I would do is not charge batteries or not extend the antenna. Besides I wouldnt have started this thread if that was the case Lets forget about the newbie stuff this is serious lol! I do remember hearing the engine miss a beat or kinda drop a few RPM's right before it went wide open. I have the 8103 is that not PCM?
Old 04-14-2006, 09:15 PM
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Default RE: Cessna out of control

ORIGINAL: Liberator

On board glow CAN cause problems. Best thing to have someone restrain it and do a range check with the motor running and off. If you see a big difference, then you may need to work out shielding or even go to a new glow driver.

Did you have the antenna fully extended when this happened?

hmmm not sure what you mean here the on board glow is on at idle plus a tad of throttle when the plane is turned on doesnt matter if the engine is running? If I have interferance from the glow it would do it with or with out the engine running.
Old 04-17-2006, 03:27 PM
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mwarren400
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Default RE: Cessna out of control

I have to ask you...were you using a JR Sport 125 Servo for your throttle?? You mentioned the 8103...you might want to check to see if you inadvertently added a mix for the throttle. I've managed to accidentally change a mix.
Old 04-17-2006, 03:43 PM
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hattend
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Default RE: Cessna out of control

Did you have your antenna all the way up?

Don
Old 04-18-2006, 08:15 AM
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ehfleming
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Default RE: Cessna out of control


ORIGINAL: RCHYFLYER

ORIGINAL: Liberator

On board glow CAN cause problems. Best thing to have someone restrain it and do a range check with the motor running and off. If you see a big difference, then you may need to work out shielding or even go to a new glow driver.

Did you have the antenna fully extended when this happened?

hmmm not sure what you mean here the on board glow is on at idle plus a tad of throttle when the plane is turned on doesnt matter if the engine is running? If I have interferance from the glow it would do it with or with out the engine running.

It might matter. Does your OBG actuate by micro-switch or electronic switch? I found that micro switches can cause rf for a few reasons; mostly due to vibrating contacts. I use electronic switches, like EMS Jomar or similar. Your problem may have been caused by the number and power demands of your servos plugged into your receiver. The more (and powerful) the servos, the greater possibility for glitching. Doesn't matter much if the rxvr is pcm or ppm, although pcm rxvrs can usually handle higher demands. If you are using hi-torque servos all around, you may need to use twin rxvrs and batteries to share the load. Sometimes, just replacing the battery with higher capacity helps; but I don't think that is a long-term solution. I hope you rebuild.
Old 04-18-2006, 09:30 AM
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Default RE: Cessna out of control

The 8103 is a PCM radio, but only when switched to PCM mode. And, the receiver has to then also be a PCM receiver compatible with the JR radio. If you had your radio in PCM mode with a PPM receiver, then I'd suspect you'd have never gotten past the range check. Sounds like either interference, or an inadvertant mix when you were mixing to get the glow driver mixed into low throttle settings--might have accidentally coupled throttle to rudder, or something like that???
Old 04-18-2006, 09:44 AM
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Default RE: Cessna out of control

I'm sure you checked, but the only other thing I can think of is the screw that attaches the throttle lever to the throttle. Sometimes it works loose and then the engine has a mind of its own.
Old 04-18-2006, 08:23 PM
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Default RE: Cessna out of control

obg works off of the throttle connection for the servo then you adjust a pot on the obg board to activate thru a range from idle on up! you dont mix the obg with the radio it has its own board no switches, the battery is 2100 mah the servos are digital ds811's but the throttle is a 527. the radio is set in ppm mode. No mix with the throttle I'm thinking it was a hit from another source.
Old 04-19-2006, 07:23 PM
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wilsonad2
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Default RE: Cessna out of control

Hmm, lots of ideas already. I've got a couple more thoughts, though. The underground wires probably didn't have anything to do with it--the 18" of dirt would pretty effectively shield them from our RF frequencies. From the original post, I'm not sure where the relative positions of the transmitter, car and plane were when incident happened. I'm assuming that the plane may have been close to the car (which is a great reflector of RF from the transmitter). If the transmitter was on the same side of the car as the plane, there may have been some funky interference between the direct signal to the plane from the transmitter and the reflected signal due to their being slightly out of sync due to the difference in path length. If the car was between the plane and the transmitter, the reciever may have gone into a shadow from the car where it wasn't getting a good signal. The loss of RPM/missing a beat sounds like an engine problem, probably a mixture adjustment "feature" that showed up as it (probably very quickly) went from idle to full throttle.

I know this doesn't really answer the "why?" but I hope that it helps rule out what it isn't. It sounds like failsafe, antenna extension and low batteries have been ruled out. Onboard glow still seems suspect to me, antenna routing in the plane may have played a role, too. My experience is that our equipment is reliable and most problems are related to installation, the operating environment, or operator error.

Is there anything more that you can tell us about the incident? I think it might be beneficial to know how long it took to go to full throttle, if it stayed at full throttle or if it varied before it crashed. Did you happen to notice whether the throttle servo was moving as you walked up to the plane after it stopped (I'm assuming that you left the transmitter on until the receiver was turned off, unlike some newbies ).
Old 04-20-2006, 08:11 AM
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Default RE: Cessna out of control

What a beautiful plane. Is it black and white or is that a dark blue? Anyway, I hope you can repair it.
Old 04-20-2006, 08:58 AM
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Default RE: Cessna out of control

Not all OBG's work like that. But, if indeed yours does, then you would not have any mixes. Just throwing out suggestions. Seems as though you are dead set on the fact that it was a hit, so I'll just agree with that and move on....
Old 04-20-2006, 11:27 AM
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Default RE: Cessna out of control

"Lets forget about the newbie stuff this is serious lol!"

So just becasue you have money invested and have been flying forever you can't forget to pull the antenna up?

Sounds like you know more than all of us so I am sure you will figure out the problem eventually.

Good luck!

Old 04-20-2006, 07:01 PM
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Default RE: Cessna out of control


ORIGINAL: mwarren400

I have to ask you...were you using a JR Sport 125 Servo for your throttle?? You mentioned the 8103...you might want to check to see if you inadvertently added a mix for the throttle. I've managed to accidentally change a mix.
Do these SX have a bad reputation?

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