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Old Nov 15, 2006, 04:19 PM
craddojc is offline
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Discussion

Lost control of plane, is this a Rx or Tx problem?


Why would a plane fly on its own and not repond to commands? I recently lost control of my plane and it went off flying on its own.

The plane did not respond, just kept flying at a constant speed and altitude regard less of what I did on the transmitter. The problem happened when the plane was about 50 yards away, and it kept going until it crashed into a house about 300 yards away. Altitude was constant at about 10 feet. Can I be sure if the problem is in the transmitter or in the receiver?

I fly a scratch built scale Brewster Buffalo running off a brushless motor and a lipoly battery. It has a GWS 6 channel receiver, and an old Hitec Focus 6 transmitter, and has been in use for the last year with this equipment without any problems.

I am very spooked about this...
Jeff
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Old Nov 15, 2006, 04:32 PM
slipstick is offline
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Complete lack of control could be almost anything. The commonest causes are probably:
a) in the plane - failure of a switch or Rx battery if you're using a separate Rx battery. Could also be Rx, crystal or BEC failure but they're pretty rare.

b) at the transmitter - antenna loose/unscrewed or Tx output died.

You can tell if the Tx is still working o.k. with other receivers. It's not very likely to be an intermittent problem though anything's possible. You certainly need to check anything in the plane that's still intact. Bear in mind that if it was a severe crash the Rx crystal is likely to be broken now.

The last time I actually saw a problem like that some fool had not extended his Tx antenna - but luckily I got it extended in time and saved my plane .

Steve
Old Nov 15, 2006, 04:45 PM
eflightray is offline
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An itch?. Scratch build.
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Shouldn't your ESC have automatically shut the motor down with loss of signal? I thought all modern ones did.

Does anything still work?
Old Nov 15, 2006, 04:59 PM
wattsup_kz is offline
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Check the jack in the TX where the battery plugs in. On my Laser 4 the solder joints broke loose causing random shutoffs. Wiggle the plug with the radio on and see if it shuts off.

Brian
Old Nov 15, 2006, 05:24 PM
TimOBrien is offline
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Quote:
Originally Posted by craddojc
I am very spooked about this...
You should have been around 20 or 30 years ago when radio failure was the norm instead of the rarity it is today!!

Old Nov 15, 2006, 06:07 PM
xFxLxYxExR is offline
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I have had that happen many times with those cheap GWS recivers. I guess its a "you get what you pay for" thing. Now you cant just say it was your reciver without some testing.

...XF
Old Nov 15, 2006, 07:19 PM
JEB21 is offline
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Quote:
Originally Posted by craddojc
Why would a plane fly on its own and not repond to commands? I recently lost control of my plane and it went off flying on its own.

The plane did not respond, just kept flying at a constant speed and altitude regard less of what I did on the transmitter. The problem happened when the plane was about 50 yards away, and it kept going until it crashed into a house about 300 yards away. Altitude was constant at about 10 feet. Can I be sure if the problem is in the transmitter or in the receiver?

I fly a scratch built scale Brewster Buffalo running off a brushless motor and a lipoly battery. It has a GWS 6 channel receiver, and an old Hitec Focus 6 transmitter, and has been in use for the last year with this equipment without any problems.

I am very spooked about this...
Jeff
Did you do a range check before taking off?
Old Nov 15, 2006, 08:02 PM
Kenny Sharp is online now
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turn, turn, turn.
One time I saw some hippe turn off his radio while attaching his strap.Fortunatly, after 1 minute of flying in circles, I managed to turn the radio back on and save the plane.
Old Nov 15, 2006, 08:02 PM
Sparky Paul is offline
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It sounds like a switch failure in the plane.
I've had that happen.
A battery failure usually ends in a crash just a few seconds after the failure.
Old Nov 15, 2006, 08:09 PM
BlazerB52 is offline
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Was the transmitter designed for Alkaline batteries and you used rechargables?

There is a voltage difference of around 2.4volts. Could that be the problem?

Alkaline(disposable)=8X1.5v= 12v
Rechargables =8X1.2v=9.6v

That is what caused a problem for me.
Old Nov 15, 2006, 08:20 PM
screamin' eagle is offline
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R/C Chronic
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Does the transmitter use a soldered and shrink-wrapped battery pack, or one of those spring-loaded battery trays. On the latter, the contacts go bad and you lose power.
Old Nov 15, 2006, 09:06 PM
BlazerB52 is offline
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Screamin eagle,
Good point.

Had that happen also. Makes the thing go nuts when battery is jiggling in the TX. I don't use cheaper radio's anymore.

Hope problem is solved/found.
Old Nov 16, 2006, 12:01 AM
BillM is offline
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I doubt that using "rechargeable" batteries instead of alkaline batteries would cause a problem. Transmitters are designed to operate over a range of voltages. Most "dry" transmitters--those that use alkaline batteries--also have after market rechargeable battery packs available to those who wish to use them.
Remember the voltage of "new" alkaline batteries is 1.5 volts. The voltage drops with use. Several of my radios come off my chargers with battery voltages of over 11 volts but quickly drop to 9.6 as I use the transmitter.
The moral of my story is the transmitter doesn't care what kind of batteries you use so long as the voltage is within the design parameters of the unit.

BM
Old Nov 16, 2006, 05:49 AM
vintage1 is offline
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I think the key thing that someone has pointed out is that the motor didn't cut. ALL ESC's will go low throttle on loss of signal..if the motor kept going, it was getting signal.

Which means that most of the transmitter was working..or someone elses on the same frequency was, anyway.

Sounds like a subtle problem in the transmitter..might be low batteries, might be a fault - and a hard to find, intermittent and expensive one.

I would at this point toss the transmitter, and get a new one.
Old Nov 16, 2006, 10:35 AM
Popsflyer is offline
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Oldie but goodie
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What's the weight of this plane? I personally would be afraid to fly anything over 16oz with an old radio system and especially a GWS receiver. I actually threw away an old working Futaba 4ch system (about the same vintage as your Focus), because I didn't feel comfortable using it.

I've seen fly-aways before in RTF planes with cheapo radio systems (not your case) and heard of fly-aways with top notch PCM systems that locked the pilot out during a failsafe.

My first thought would be from outside interference. Many of the older radio systems were AM and are not as solid in todays crowded RF enviroment as our newer FM systems.


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