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After failsafe crash procedures??

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After failsafe crash procedures??

Old 05-07-2007, 07:28 PM
  #26  
Chris Smith
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Default RE: After failsafe crash procedures??

Rob,
Your input helps a lot. I'm leaning more and more toward a battery issue as cause, although I may never know for sure.

I am finding I have more homework to do regarding the pros and cons of 6V batteries, dual, batteries, power boxes, and regulators.

One of the supposed benefits of a 6V battery was built in cell redundancy. If a cell goes bad you still have 4 putting out 4.8V. If this was true, why would our jets have exibited voltage problems, and in my case a failsafe loss? Assuming the theory is not myth, then maybe the reality is the voltage drops off so fast below a certain number, that the 5th cell is not of much benefit. Then is there any other reason to use 6V other than extra servo power when the charge is within working limits?

I've considered battery back-up systems and regulated power bus set-ups. But I've also heard of over-loaded, over-heating regulator issues as well. Seems I just read of a Weatronics Rx in a jet recently that crashed presumably due to failsafe. There are no garantees. I went 20 flights before a problem.

Thanks,
Chris

Old 05-07-2007, 09:37 PM
  #27  
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Default RE: After failsafe crash procedures??

I quickly scanned this thread so I might have missed something....

However, I have been flying helicopters for many years and whenever I have a radio related problem that points to the RX I NEVER use that RX ever again, for anything...period. Matter of fact, if I loose a machine because of a lock-out or something like that I take a hammer to the RX and toss it. This way I am never tempted to try it at some later date.
A 2 thousand dollar helicopter is not worth a 2 hundred dollar receiver.

But thats just me talking....
Old 05-08-2007, 09:16 AM
  #28  
rcdriver22
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Default RE: After failsafe crash procedures??

Plenty of good advice given to remedy and to check back on. To really check over all the suspect radio gear after a crash you might substitute individually the crashed radio parts, one by one into a stable flying hack like a junior 60 which can fly hands off, with good known gear to isolate any problem items. Personally, I'd set all the gear aside and consider for the bin crystals, rx, switch harness and battery. Range checking each and every time with engine running with all servos testing together to extreme travel at distance.

Even then this is risky, as in your case many items raised, point to a sudden loss of power, a dry joint or loose connection. In some instances a power or voltage drop can send the servos over to an extreme locked position, certainly seen this on a Futaba system before, on a pack that was its way out. While the servos did not snap, they moved progressively over to a locked position

Just for background as to voltage, others more technical might confirm, that on a 5cell rested pack after a full charge say its reading 6.3 -6.5 volts and fully discharged 5.55 volts. While 5.5v is higher than 4.8v there is nothing the pack can deliver power wise. At 6.5 volts if one cell is dying there is no back up that with four cells at 4.8 volts the pack can again deliver usable power to the RX and servos, since there is an inbuilt resistance caused by the dead cell.

Paul
Old 05-08-2007, 06:06 PM
  #29  
Chris Smith
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Default RE: After failsafe crash procedures??

Thanks Paul, your input on the 6V with cell loss makes sense. I've done a lot of component checking. The TX and RX are sent away for check-out. We'll see what they find. I will likely not use the Rx in a jet again, but that may be an over reaction. I will change the crystal if Futaba doesn't.

The more I read, the more conflicting information on battery characteristics I find. But I'm not surprised. In my profession, working with electrical engineers (EE), you can lock 2 in a room to investigate a circuit and they'll come back with 4 opinions. Even with a MIL spec design standard.

So...we play the odds. Folks set up their jets with what has worked, either through experience or others' experiences. Trouble is, solutions vary. What I would like to learn is the battery set-up that jet flyers are having the most success with.

Chris
Old 05-30-2009, 08:42 AM
  #30  
ScottK
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Default RE: After failsafe crash procedures??

As a previous poster recommended, Itoo add a small control surface deflection component tofailsafe programming to differentiatefailsafe hold from "free flight", A.K.A. reboot,bad battery, or badswitch/connection. Otherwise, at distance and/or short duration, they are indistinguishable.

As to your snap roll, I've personally seen plenty of times when during a control lockout, the pilot begins to move the sticks ever more vigorously to seek control, only to have the plane begin responding while the sticks were near "the corners".

I saw this virtually on a YouTube video just the other day.Aircraft takes off and begins to bankstarboard away from crowd,then goes into hold for about 2seconds- continuing right roll without enough elevator to keep altitude.While pilot is pulling full up elevator with aileron jammed left - control returns...instant hard left spiral into terra firma!

It's been a while since your original post. I hope everything's going great for you now!
Old 05-30-2009, 10:29 AM
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Default RE: After failsafe crash procedures??

holy bring a thread back from the dead batman!..... 
Old 05-30-2009, 04:06 PM
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Default RE: After failsafe crash procedures??

Old 05-30-2009, 05:29 PM
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Default RE: After failsafe crash procedures??



You never know. The original poster might have been checking this thread every day for over 2 years waiting for the right response.





and then again, maybe not!


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