Greg Rullman
President
Duke City Electric Flyers
Crash of the Week: Had a plane go in today. My little red rocket, Yak-130 #5. Everything good on 2 prior flights. Fast pass. Pull straight up to ~300'. Uh-oh! Power cut. No controls. Slows down. Flips over. Straight in from 300'! I checked controls all the while and lowered the throttle bringing it back up just in case. Nothing. It was like all power was gone. Well, nuts!!
On the tear down, I took things slow. Remembering the flight, while tearing things apart to inspect, save, or throw out, I found the throttle and rudder leads pulled out of the Rx. The Rx was also pulled about 3" forward of it's mount, as was the ESC. That would kinda mean they were still plugged into the Rx, but not necessarily. Besides the power outage happened way before the crash.
Now, the battery ejected forward after the nose hit first and things went their own ways. The nose was also detached and out in front. It would make sense that this sudden jerk unplugged the 2 leads as they both travel to the ESC and the forward bay - Throttle to ESC and Rudder Y'd to Nose Gear steering. To me, it looked like the crash caused the unplugging. So, why did the system quit up high?
I thought maybe the ESC fried the BEC, and caused the blackout. Checked it with a new battery. 5.2 V on the throttle plug. Hmmm... Note: I haven't checked it with the old battery, but I think I will as it is bent bad but possibly still capable of delivering current.
Then I thought, did the Throttle become unplugged after that last torque roll? If you've ever seen this jet torque roll, you'll know it's pretty violent. Plugged everything back into the Rx. Everything worked like normal. Rx light solid. ESC beeped normal. Fan actually still ran very smooth. All controls working. The servo plugs are even really difficult to get in and out. OK, then... !
So, 507 flights (yes, I keep a logbook) on 5 different Yaks all with the same Rx, 3 different fans and 2 different Speed Controls. This story doesn't have a result. Sorry. This is one of those crashes where I may never know.
What I wanted to instill on you is to be methodical. Don't let emotions take over. Remember the flight itself and maybe the initial setup/turn on procedure. Look at the crash site. Etch in your mind where things ended up. Pick up ALL the pieces. This can be hard, as some parts can be quite small and broken. But, they are all indicators of what happened. Check equipment for proper voltages, mechanical integrity, etc. You become your own NTSB. Taking your time, being thorough, remembering the moment can all help put the accident back together again. And... most of the time, you will know immediately what the heck happened.
Except sometimes! I know I will be mulling this one over and over and over...
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