The flying monkeys got me...

Helis and fixed wing

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IRCHA 4345
AMA Intro Pilot Instructor

Saturday, June 23, 2012

Gremlins

Today was gremlin day.
 
The winds at BMF where too high, so I pretty much was the only one with a bird in the air. They ran to 6 mph at first, but quickly bumped to 10-15 mph with variability, but pretty much from the east.
 
Started out the day with the Thunder Tiger eHawk. It remains a POS. She has such inadequate tail repsonse to elevator and rudder as to be virtually uncontrollable. Shot straight up though she is set up a scosh nose heavy. It was all I could do to get her back on the ground. I started thinking about all the things I might do to extend the length of the short servo arms on the already max travel and d/r servos... then I gave the damn thing to George Vilchez and his son Antonio. Let them sort it out. I had decided it wasn't making the trip to Dayton, so I had no problem giving it to them. They love the challenge and will undoubtedly get her flying just fine! You can see her sulking in the car aft her embarassing behavior today, in the above pic...
 
Flew the PulseXT 25e, practicing crosswind landings. The winds were due east, so landings from either end of our 36-18 runway provided a nice experience. She was buffeted and carrried in some gusts, rolls were done with caution, but it was fun to finally get somehing up in the air and get my thumbs back.
 
Set up to fly the Sbach and in preflight found her rudder servo was stripped. To be honest I didn't check it before I left the house so it could have taken a hit in the same incident that tore the tail gear off. When I got home I fortunately had the gear that stripped on the JR MN48, always that damn middle one, and replaced it. Reinstalled the servo, reset it and she's as good as new. (See my earlier post on changing servo gears. Waaaayyy cheaper than buyting a new servo, and so very easy to do)!
 
Took the EXI 450 Beast X out. Noticed a programming error and reversed the offending servo. Things looked good, took her back out and she did a major spin out breaking her tail boom and stripping the pitch servo. I hadn't put any inputs in. When I got home and changed out the tail boom, replaced the pitch servo and rechecked the programming I found a couple of things I should have changed in the rest of the programming after changing that pitch servo direction! The ever important reason detre gimbal response was all backwards, and the tail servo, for some reason, was set to sense in the wrong direction. Really? I'm not usually this careless... My inexperience with programming the BeastX, which itself is easy, caught up with me, and my inexperience flying it let me miss the mistakes I made. Now I have a FBL preflight routine... The spin out and twist was like a snap roll on the ground. The BeastX saw a wind gust on the rotor as a push to one side, and thinking it was correcting it pushed it over to that side, and thinking it needed more tipped it more. Meanwhile torque effect started a yaw and the mis-sensing tail gyro commanded a correction, but in the wrong direction. So, Dick Clark, what we saw, and why the boom snapped at the frame, was a violent and self progressing snap roll! The blades and that stalwart Tarot head survived, but I did replace the tail blades just because they were worn from tip strike. This time I went through the entire programming step by step, which took only a couple of minutes, made the correct settings, and took her outside. She flew just fine over my driveway in a still very brisk wind, and was perfectly controllable. Lesson I should have learned when I did the same thing with the Tarot yesterday: when you change one thing, especially a major thing such as a servo reversal, check the entire 3G programming.
 
Took my Frankenheli Tarot ZYX up and she hovered fine, and that vibration I noticed yesterday at certain frequencies showed up again. This time Dick Clark took a look and found the main shaft head bearing had some play small but quite noticeable. I changed out the entire head bearing platform from one I scavenged from another 450, and now she is tight. It makes a lot of difference. Tomorrow I will test fly her in the driveway. Like yesterday, in the brief hover before the vibration tried to shake her apart, she was nice and stable, suggesting the Tarot ZYX is a good stable inexpensive 3G system. I was quite impressed that the severe vibration did not affect they gyro at all, she held her head and her pitch/roll just fine. Impressive.
 
The HDX 500 flew fine, but I noticed a worsening abiity to hold her head, and finally had to set her down. On re-examining her I realized there was no rudder at all... the Align DS520 tail servo, probably 5-7 years old, had finally died. I ordered a replacement Himax ES9257 Futaba clone, same one I will be putting on the HK 500cmt. Half the price and people really like it. For my emerging sport flying its just fine.
 
So beating back the gremlins. Fixed everything except the tail servo on the HDX, but the issue identified. I am looking forward to building the HK 500cmt belt driven heli as its parts arrive this week. I am determind to push my heli skills forward hard these next few months. I haven't been able to fly the sim since the kids took over all the HDMI spots on the media room TV, but will be taking it downstairs to my bedroom TV and get some more time on it. Need work on orientation.
 
On a side note, I have been working on flying most of my helis at 100% rates with about 40% expo. My 500's are easily flown this way. I find I sometimes have to dial the rates down for the 450s significantly, to at least 75% to keep it from over reacting. Some people are very against dialing down the rates, but I really don't understand that. I can see for 3D, but I am no where near doing that... I think I will keep my rates wherever I am most comfortable withthe, and dial them up as I get better.
 
 
Thanks to Ray for the chili dogs!
 

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