[NSRCA-discussion] Lost Abbra

Tue Aug 8 03:26:48 AKDT 2006

Keith,

The crash was so hard that everything was loose.  Soon after the crash I assumed that the battery came loose (snap g's) and the battery got disconnected because came loose.  However, after analyzing the crash I found that the battery still was electrically connected with the system since one servo was buzzing hard.  Later after checking with more detail at home I turned the TX on and RX on and the radio worked fine.  Therefore, I the original conclusion that the battery came loose and got disconnected is not correct.

Last night I checked the receiver antenna using the ohm meter.  The antenna is OK.  Also I did a vibration test on the switch and receiver and checked all wires and everything is working fine.  Looks like is going to be very difficult to know what caused the crash.  I also checked the servos that survived the crash moving slowly and never found a bad spot.  

Thanks,

Vicente "Vince" Bortone   

-------------- Original message -------------- 
From: "Keith Black" <tkeithb at comcast.net> 

Vince,

Am I to understand that the battery was loose in the plane? If so, do you know if this occurred due to impact or if this occurred during the snap?

Keith
----- Original Message ----- 
From: vicenterc at comcast.net 
To: NSRCA Mailing List ; 'NSRCA Mailing List' 
Sent: Monday, August 07, 2006 9:03 PM
Subject: Re: [NSRCA-discussion] Lost Abbra

Hi Richard,

I said that wrong.  It was really a lot more than 90 degrees.  The plane stop almost inverted.  Therefore, the over rotation was close to 180 degrees.  You have a good point.  That is reason I always said the it is pilot error unless I can find the reason of the mechanical failure.  Let me explain a little more.  I snapped to the right because we had 90 degree cross wind.  I was flying the manuever left to right and the wing was blowing out.  Probably 10-12 mph.   Therefore,  I was snapping into the wind for obvious reasons.  When I noticed that ailerons were not responsive I did apply down elevator (releasing the aileron first).  The speed was high because I did a large Inmelman turn so I don't see that the plane was in stalled condition.  However, I could be wrong.  Charlie was calling for me I he could give us his opinion in regard the stall condition.  If I did s! nap awa y from the wind there could have been more chances of stalling.   I use low rates.  Around 10 degrees in el
evator, 12 degrees ailerons.

I really new that there was something wrong very early because I couldn't stop the snap.  It was almost instant feeling that I didn't have control after I did the snap.

Vicente "Vince" Bortone
-------------- Original message -------------- 
From: "Richard Strickland" <richard.s at allied-callaway.com> 

I suppose that if the airplane were over rotated by 90 degrees and at least still in a semi-stalled condition in knife-edge, the controls would potentially be slow to respond.  In a right hand snap, the right wing would be stalled and if it were pointed toward the ground—still stalled--and the fuse was washing out the left—upper—un-stalled--panel, then that would account for the non-responsiveness of the ailerons.  Aircraft can still be stalled at high speeds and depending on the timing and amount of input—maybe exaggerated with high rates with big expo, a secondary stall/spin can take place making you wonder ‘how did THAT happen?!’.  ! Not all that unlikely a circumstance with as slippery as these critters are….  And you might have just had some really lousy luck with wind shear at that precise moment.  I am a Charter Member of SAD.

RS

-----Original Message-----
From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of vicenterc at comcast.net
Sent: Sunday, August 06, 2006 6:52 PM
To: nsrca-discussion at lists.nsrca.org
Subject: [NSRCA-discussion] Lost Abbra

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.  < o:p>
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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