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-   -   Then there was this (https://www.rcuniverse.com/forum/arf-rtf-75/8398141-then-there.html)

basman 01-25-2009 03:48 AM

Then there was this
 
1 Attachment(s)
Ok you may have seen the rebuild at "Super Star will shine" http://www.rcuniverse.com/forum/m_8333307/tm.htm well this is how it ended. Re-maiden flight all ok but engine overheats bring it back in for landing. Needed 4-5 clicks up trim was pulling to left and differant prop. The 18x6 was just not suited. Cowl was pulled off prop changed refulel, even though we only had a minute or so of flight. New prop 17x10 timber.
Engine running better ( Super Tiger 3250 ) the prop all the better. Verticle climb good inverted flight good, small amount of up elevator. Cof G was set as discussed in forums rc universe , 125 mm from leading edge of wing at side of fuse. To achive C of G the battery was installed as far back in the tail as possiable, by opening up the bottom of the fuse then reinstating the ultra coat.

Refuled and ready for third flight. This project was a joint effort, so I was not actually flying at this stage. I was watching from the pitts, the flight was going well. Climbed to a good height pulled into a dive then good inverted flat spin, if you have read the reveiws ( Seagull " Supper Star " 120 ) it performs quite well. It then came past what looked about 40- 50ft the length of the strip. At the end how ever it rolled to the left and then banked straight for the ground. What I saw next could not do if I tried, it pulled up as it was about to hit the ground, both wheels touched then went straight up to about 10- 15 feet. All I could think was what a save, you only do this stuff on the sim!!!!!!!!! But to no avail it didn't stop there it made its way back to the ground droped a wing and cart wheeled.

When we got to the aircraft there was no life in any flight surfaces. The Pilot said he had lost control half way down the strip. Looking at the switch, no light for power indicator. We checked the battery and
sure enough it was very low on the indicator. Ok so charge process was like this. It was a brand new battery purchased about a month ago. I use a swallow ac/dc 2. The battery 2600mah ni mh. First charge was full day at 0.2amps. Second charge / cycle was a discharge @ .10 and charge at .7amps. This process only took 3_4 hours. The battery showed full on the metre. During flight prep the next morning the battery was checked again and showed to be holding full charge. Now the total of the 3 flights there would not have been a full tank of fuel used. Maybe 10- 12 minutes of total flight. The result was loss of aircraft, any idea why a battery would only last this long

tailskid 01-25-2009 07:14 PM

RE: Then there was this
 
OUCH!!!!

jrf 01-25-2009 09:12 PM

RE: Then there was this
 
The battery could have gone bad from vibration, or you could have had a couple of servos binding up.

Jim

basman 01-25-2009 10:53 PM

RE: Then there was this
 
That sucks !!!!!!!!!!!!

basman 01-25-2009 10:55 PM

RE: Then there was this
 
I will take the battery to shop on Tues to get it tested. Shamre to loose all that work over a small thing like dead batt

cavandish 01-26-2009 01:58 AM

RE: Then there was this
 
"The battery 2600mah ni mh. First charge was full day at 0.2amps. Second charge / cycle was a discharge @ .10 and charge at .7amps. This process only took 3_4 hours."

There is no way you battery could of been fully charged ?

To fully charge a 2600mah from dead flat at .2 of an amp would take about 13 hours plus say 3-4 hours for loss, so longer than a day ?

if you then discharged at .10 and back up to 'full charge ' all "in 3-4 hours" there is no way that you pack could of been anything like fully charged ?
Ive made a similar mistake myself, I had a faulty pack that my delta peak charger was indicating was full, it was not (I found out later the the metal of two ajoining cell cases was touching( the case is neg) meaning that one cell was getting by passed during the charge process) sure enough my onboard monitor was flashing in the red when i worked the servos, I just thought "those monitors are rubbish" sure enough my rx locked out for several vital seconds, I was lucky to be able to land a beatifull 25% Zlin 50L in one piece.

basman 01-26-2009 03:26 AM

RE: Then there was this
 

cavandish
Glad to hear your 25% Zlin 50L survived. Do you have any pics never heard of one? In the back of my mind the hole discharge - recharge seemed to quick, should have taken notice to that small voice!!!! The things we think of later.

cavandish 01-26-2009 04:05 AM

RE: Then there was this
 
"The battery 2600mah ni mh. First charge was full day at 0.2amps. Second charge / cycle was a discharge @ .10 and charge at .7amps. This process only took 3_4 hours."

There is no way you battery could of been fully charged ?

To fully charge a 2600mah from dead flat at .2 of an amp would take about 13 hours plus say 3-4 hours for loss, so longer than a day ?

if you then discharged at .10 and back up to 'full charge ' all "in 3-4 hours" there is no way that you pack could of been anything like fully charged ?
Ive made a similar mistake myself, I had a faulty pack that my delta peak charger was indicating was full, it was not (I found out later the the metal of two ajoining cell cases was touching( the cell casing is generally neg) meaning that one cell was getting by passed during the charge process) sure enough my onboard monitor was flashing in the red when i worked the servos, I just thought "those monitors are rubbish" sure enough my rx locked out for several vital seconds, I was lucky to be able to land a beatifull 25% Zlin 50L in one piece.


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