[NSRCA-discussion] Lost Abbra
Jay Marshall
lightfoot at sc.rr.com
Mon Aug 7 08:22:33 AKDT 2006
To check for bad spots it is necessary to move each servo SLOWLY, one at a
time and watch for the others to glitch. Moving them rapidly will run right
past a bad spot and you won't see it.
Could the root cause been RFI?
-----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: Monday, August 07, 2006 11:57 AM
To: NSRCA Mailing List; NSRCA Mailing List
Subject: Re: [NSRCA-discussion] Lost Abbra
Jim,
I did it. I tested the system after discharging the battery. I plugged all
servos but the throttle servo that was destroy in the crash. Everything was
working fine. I used the test feature of the JR 10X to keep the servos
moving. I didn't get any smoke because the stalled servo has the gears
stalled but the motor is running freely.
I got a question. It was very hot here in Kansas last Saturday. A fellow
club member told me that NiMh batteries are susceptible to Kansas heat. It
was over 100oF and inside the plane could have been 140oF. Any experience
seeing NiMh failing in these conditions.
Thanks,
Vicente "Vince" Bortone
-------------- Original message --------------
From: "J.Oddino" <joddino at socal.rr.com>
A stalled or locked up servo could pull the voltage down and essentially
turn off the radio but it would seem to me that it would take some time and
the other servos would at least start back to neutral after the snap inputs
are removed. He could try plugging in the jammed servo and see what happens
but be ready to unplug it before it starts smoking.
Jim O
----- Original Message -----
From: Ron Van Putte <mailto:vanputte at cox.net>
To: NSRCA Mailing List <mailto:nsrca-discussion at lists.nsrca.org>
Sent: Sunday, August 06, 2006 8:01 PM
Subject: Re: [NSRCA-discussion] Lost Abbra
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 <mailto:nsrca-discussion at lists.nsrca.org> ;
nsrca-discussion at lists.nsrca.org
Cc: Fred Huber <mailto:fhhuber at clearwire.com>
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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