So it has been a year and a lot had happened with this project. First, she made her appearance at FFOH 2018. I had hoped she might be worth her own feature or episode, and when Stephan walked over with the film crew I thought that might be in the cards. BUT... That runway was SO tight. There was a combination of two things going on.
1: The fabric runway bunched up in front of the wheels, adding drag and making her want to nose over, and
2: The runway was just SO narrow. Like all warbirds she wants to pull to the left and you have to counter with right rudder. She ALSO requires a lot of right aileron so that the P-factor doesn't just lift the right wing right into a stall (See early flight attempts). What I really would have had to do was basically point her at the crowd that was lining the runway and HOPE no one got hit. I think I was subconsciously light on the right input so into the soybeans she went. Twice.
Damage was minimal though. A new prop and spinner and she was ready for action. Or so I thought.
I had her back out at a Warbird event at a local club a few months later and we discovered the retracts were now acting up. Basically they would unscrew themselves when pulling the gear up and then would fail. FORTUNATELY it never happened on in the air. So she was grounded for that event.
I contacted Robart and a new set of actuators was sent. These also failed during testing and she continued to be grounded. A third set was sent and installed. A few of us got together over the winter to do some flying and I was so sure she was ready to go. I don't remember if it was Joshua or Pat who recommended I cycle them one more time for good measure, but damned if they didn't fail right there AGAIN! I owe whomever that was a drink though, because again it failed on the ground and not in the air. I didn't even bother hauling her to SEFF with
@willsonman and I last month, despite that being the BEST location I've found to fly her.
When I got back from SEFF I had the bug to get her flying again. I think it was looking at John Morgans beautiful models, particularly the new Skyraider. I pulled out all of the actuators and set them up side by side looking for imperfections or failure points. I determined that the failing units seem to be seizing/locking up, perhaps due to dirt or debris (or maybe rust) in the threads. When this happens it appears the main drive motor keeps pushing until the threaded section fatigues and fails. When working smoothly the units should NOT be able to unscrew themselves, but once they've jammed and the motors continue to try to force them into place they can fail permanently.
I found that I have 3 "good" units and 3 failed units, although the motor drive section of all work fine.
So the "fix", I hope, has been found. I liberally applied white lithium grease to the threads and will be making it part of my daily post-flight checks to re-grease them and cycle them a few times to ensure the threads stay lubricated and slick. I also stepped down the voltage on the dedicated BEC for the gear. The maximum voltage for the units is 9v. I had it set to 8.5 volts, but I've now dropped it to 7v. I never had issues with the gear failing like this when I ran lower voltages, but the gear would take close to 30 seconds to pull up. Part of me suspects that the extra torque/power made from the extra voltage is what allowed the gear to stress the threads to failure. At the lower voltages even if the threads got jammed there wasn't enough force to snap the metal.
So that is it for this wall of text. I wish I had a year's worth of flight footage and pictures to share, but her last flights were about a year ago now. That will be addressed ASAP. I put the gear through 50 cycles last night with 0 issues, and found that my 1800 mAh 45C pack could easily do 100+ cycles. I'll be re-greasing them today and will be watching the weather so I can get some flights in before our clubs next warbird event. She will be back in the air soon and hopefully get a lot of air time this season.