[NSRCA-discussion] Lost Abbra

Tue Aug 8 08:51:46 AKDT 2006

I tie the battery connectors together with carpet thread. 
The main criticism I have of the connectors we use in RC is that there is no positive retention. 
John Ferrell    W8CCW
"My Competition is not my enemy"
http://DixieNC.US

  ----- Original Message ----- 
  From: vicenterc at comcast.net 
  To: NSRCA Mailing List ; 'NSRCA Mailing List' 
  Sent: Tuesday, August 08, 2006 11:51 AM
  Subject: Re: [NSRCA-discussion] Lost Abbra

  That is correct.  As we know, mother ground after the snap at the 45 degree down line is getting closer at around 60+ mph.  It is not good feeling and time past very fast in that particular situation.  I wish that the plane was flying level.  

  I checked last night and the fail safe is programmed to go all neutral in all surfaces and give a little up elevator.  After I lost control, I noticed that the plane that was almost inverted increased the angle as was approaching to the ground.  Therefore, I am almost 100% sure that the fail-safe took over.  The theory that something happen to the TX has to be consider now.  Jon Lowe suggested to check the transmitter battery door.  I noticed that the door lash in mine is very weak.  Now, I am wondering if the power to the transmitter got disconnected for few seconds and caused the crash.  Actually, I was helping a friend to set up his JR 10X few days before and the power to the TX went suddenly off.  The problem was that the battery moved down and got disconnected.  Checking last night, I found that requires just a fraction of an inch to get disconnected. !  I am going to follow Jon advise.  I am going to secure the battery cassette and make sure that the door stays closed. 

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

                 I think he said he didn't have time to try throttle and rudder-engine at idle.

                 RS

    -----Original Message-----
    From: nsrca-discussion-bounces at lists.nsrca.org [mailto:nsrca-discussion-bounces at lists.nsrca.org]On Behalf Of Fred Huber
    Sent: Monday, August 07, 2006 6:55 PM
    To: nsrca-discussion at lists.nsrca.org
    Subject: Re: [NSRCA-discussion] Lost Abbra

    But... he still didn't have throttle response, so... there had to be some form of control loss.  A stall MIGHT explain the rest, but I kind of doubt that was it.

    BTW... I have the SAD emblem stickers on my plane.  

    Aircraftus Fragmentum

    ----- Original Message -----

    From: Richard Strickland 

    To: 'NSRCA Mailing List' 

    Sent: Monday, August 07, 2006 5:49 PM

    Subject: Re: [NSRCA-discussion] Lost Abbra

    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.  

    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.   < /o:p>

    Thanks and have a nice day,

    Vicente Bortone

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