[NSRCA-discussion] Lost Abbra

Ron Van Putte vanputte at cox.net
Sun Aug 6 19:02:09 AKDT 2006 

On Aug 6, 2006, at 9:50 PM, vicenterc at comcast.net wrote:

> The battery was a little over a year old.  I cycled the battery  
> after the crash and got around 1540 mah.  It was freshly charged  
> and I was in the second fly.  I use around 200 mah per fly so the  
> battery was close to 2000 mah.  I always charge at C/10 and never  
> fast charged.
>
> I am discharging the battery now at 500 mah.  I discharged the  
> first time at 250 mah.  I will keep increasing the discharge rate  
> to check if I find something wrong.

I am willing to bet that you will find a bad servo.  Maybe Jim Oddino  
or one of the other radio wizards can explain, but a single servo can  
cause the whole system to crash.

Ron

> -------------- Original message --------------
> From: "Scott Anderson" <scott at rcfoamy.com>
> How old are the NiMh batteries... People have found the have a  
> steep drop off when going bad..
>
> scott
> ----- Original Message -----
> From: vicenterc at comcast.net
> To: NSRCA Mailing List ; nsrca-discussion at lists.nsrca.org
> Cc: Fred Huber
> Sent: Sunday, August 06, 2006 10:19 PM
> Subject: Re: [NSRCA-discussion] Lost Abbra
>
> Fred,
>
> Usually I called pilot (and/or mechanic) error until I find the  
> cause of the crash.  I haven't been in this position in a very long  
> time.  I tend to agree with you since it was clear that I didn't  
> have control.  However, the radio is working even after such a  
> crash.  There was a comment at the field that NiMh batteries can  
> cause this problem.  I will check the battery as much as possible  
> (cycle increasing the current draws) but not sure if the test will  
> be valid.
>
> Thanks,
>
> Vicente "Vince" Bortone
>
> -------------- Original message --------------
> From: "Fred Huber" <fhhuber at clearwire.com>
> In that case... it may have gone to lock out just as it was  
> finishing the snap... rather than your control input to get out of  
> the rotation, the surfaces go to neutral, it over-rotates and then  
> plays lawn dart.
>
> No response at all its very easy to thing failsafe lockout.  Since  
> the engine was already at the failsafe setting, you don't have that  
> indicator to confirm (or refute) the lockout.
>
> I wouldn't call it pilot error when the control input attempts you  
> made simply had no effect...
> ----- Original Message -----
> From: vicenterc at comcast.net
> To: nsrca-discussion at lists.nsrca.org
> Sent: Sunday, August 06, 2006 7:15 PM
> Subject: Re: [NSRCA-discussion] Lost Abbra
>
> I am wrong below in regard the fail safe in regard the fail safe.   
> The fail safe is programmed to cut the engine and set the control  
> surfaces at neutral.
>
> Vicente "Vince" Bortone
>
> -------------- Original message --------------
> From: vicenterc at comcast.net
> Yes, yesterday afternoon I lost my Abbra.  I was doing the 45  
> degree down with snap.  After the snap, I could not control the  
> plane.  This is my recollection of events:
>
> 1. I over rotated the snap for a kittle more than 90 degrees.  It  
> was clear to me at that early stage that something was going  
> wrong.  I snapped to the right.
> 2. My friend Charlie was calling for me.  He also noticed and said  
> something to put it back in position.  I told him that the plane  
> was not responding.
> 3. First reaction was to give full left to get it back upright.   
> The ailerons did not respond.  When I realized that, I tried to  
> take it out of the dive by given down elevator since was pracically  
> in inverted position.  It did not respond.  It that aptitude  
> everything goes very fast.  Finally, I tried to give up elevator  
> but was already too late.  I am aware that I applied these control  
> input.  It was clear to me that there was no reaction.  I was able  
> to realize that I didn't have control and I could not avoid the crash.
> 4. I did not have time to do anything with rudder and throttle.   
> Throttle was at idle.
> 5. When we checked the crash site. One aileron servo was buzzing  
> hard.  I disconnected the servo.  Therefore, my first impression  
> that the battery flew off and it got disconnected with the force of  
> the snap was not valid.
> 6. I took the plane home as it came from the crash.  I disconnected  
> only the ailerons servos.  I checked the radio and everything is  
> working fine.  Only two servos are not working.  The throttle servo  
> that was practically destroyed in the crash and one aileron servo  
> that the gears were stripped.  I believe that this was caused by  
> the force of the impact.  There was not evidence of flutter in the  
> ailerons before the crash or structural damage after coming out of  
> the snap.
> 7.  I believe that the plane was well over stall speed after the  
> snap.  Therefore, the plane was not in stalled condition.  However,  
> I could be wrong.
> 7. I use JR all around with digital servos.  PCM receiver with fail  
> safe programmed to cut engine and leave the servos in the last  
> commanded position.
> 8. I use 2300 mah NiMh battery (4 cells AA Sanyo).  I checked the  
> battery voltage and was at 5.15 volts after the crash.  Discharged  
> the battery and gave 1540 mah using 250mah rate.  I am planning to  
> cycle the battery with higher loads.
> 9. It was very hot day.  The plane was sitting in the sun and it  
> was second fly of the day around 2:00 PM.  Easily was close to 100 oF.
>
> At this point, I have to admit that has to be pilot error since I  
> have not been able to find a definitive cause of the crash.  It is  
> clear that the snap initiated some kind of failure.  Other pilots  
> think that the NiMh battery gave up at high currents during the  
> snap and caused the crash.  I have been flying this type of battery  
> for two years now with no problems.
>
> I am informing this to the group since I would like to have your  
> feedback.  If someone had a similar problem and found the cause of  
> the crash, please let me know.  I am going back to my backup plane  
> (the old hydeout).  I have a brand new Abbra so need to put it  
> together.
>
> Thanks and have a nice day,
>
> Vicente Bortone
>
>
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