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Old Jul 09, 2012, 01:58 AM
Registered User
United States, CO, Colorado Springs
Joined May 2012
65 Posts
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EXI 450 is "wobbling" in flight.

Last week I had my first real crash with my EXI 450. It was all my fault doing something I shouldn't have done while learning. I hit the throttle too hard which I expected would cause a quick altitude gain. What happened though is the bird went out of control for reasons I don't know. I had almost regained control but it was too late and I hit the ground. I ended up breaking the blades (cheap wooden ones) and bending the feathering shaft. I also bent the stabilizer bar.

I replaced the blades and the feathering shaft but I thought I could just rebend the stabilizer bar to make it usable again. I'm thinking this was a mistake as the bird now has a back and forth wobble to it. I can still fly it ok, but there is definitely something wrong as the wobble is a VERY pronounced one that makes the heli go up and down from front to back while hovering at a high rate of speed. The only other thing I think it could be is the main rotor head I can't get tight enough onto the shaft. It has a pretty good amount of play when I move it back and forth. I've tightened the screw as hard as I can without stripping the heads and I can not get it tight enough to take the slop out.

Sorry if I didn't explain this well enough. I'm still very new to flying 450's. Today was my 20th flight, and it was the first one where I had plenty of room in a huge treeless and people less park. I did pretty good too! I never crashed even thought the heli was wobbling.
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Old Jul 09, 2012, 02:13 AM
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zen@lanset.com's Avatar
Berkeley, California
Joined Jan 2007
3,699 Posts
You are usually better off installing a new fly bar.

You can squeeze the head block in channel lock pliers to make it tighter on the main shaft, although this maneuver will not cure a bent head block; in which case you need a new one.
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Old Jul 09, 2012, 02:16 AM
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United States, CO, Colorado Springs
Joined May 2012
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Quote:
Originally Posted by zen@lanset.com View Post
You are usually better off installing a new fly bar.

You can squeeze the head block in channel lock pliers to make it tighter on the main shaft, although this maneuver will not cure a bent head block; in which case you need a new one.
You know, the blades have hit the ground a few times now, and I'm still on the original EXI main shaft. I have 3 replacement Align main shafts sitting on my work bench right now. I think what I will do first thing is to put one of these on tomorrow just to rule out a bent main shaft. It just sucks that I had to get stupid and crash it. It was flying perfectly before. It was hovering as easily as my little V911 does!
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Old Jul 09, 2012, 12:20 PM
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Berkeley, California
Joined Jan 2007
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I think one of the biggest frustrations in this hobby is crashing a perfectly tuned model. But that is how we become expert diagnosticians and mechanics.
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Old Jul 09, 2012, 01:35 PM
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Denmark
Joined Apr 2011
518 Posts
Quote:
Originally Posted by zen@lanset.com View Post
I think one of the biggest frustrations in this hobby is crashing a perfectly tuned model. But that is how we become expert diagnosticians and mechanics.
I dont think I have any damage after losing control... but I will never know as my 450 lies on the bottom of the lake near my house. My mechanic skill will improve with the new one.
And dont worry.. I never fly over the lake. The flying site is about 350 meters from the lake. Just lost it
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Old Jul 09, 2012, 05:11 PM
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United States, CO, Colorado Springs
Joined May 2012
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Woohoo!!! It's back to flying almost perfectly again. I just have to adjust blade tracking. Even with blades that aren't tracked right though, it's smooth as silk now. I went through an entire battery pack in my backyard just hovering around and flying back and forth. I flew for over 7 minutes and my batt voltage is still at 11.08. Am I safe to go below that?
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Old Jul 09, 2012, 05:59 PM
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Berkeley, California
Joined Jan 2007
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Individual cell voltage should not go lower than 3.2. I stop flying when they are at 3.7 - 3.8, which happens when the Tx timer is set for 5 minutes.
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Old Jul 09, 2012, 08:51 PM
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United States, CO, Colorado Springs
Joined May 2012
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Originally Posted by Qtop View Post
I dont think I have any damage after losing control... but I will never know as my 450 lies on the bottom of the lake near my house. My mechanic skill will improve with the new one.
And dont worry.. I never fly over the lake. The flying site is about 350 meters from the lake. Just lost it
I have a waterfall in my backyard that I built for my wife. A few weeks ago I was flying my crappy DH9116 (I Hate the thing) and it's tail rotor decided it wanted to stop responding to my control again. This time it did it right over the pond section of the waterfall. Hehe, it dropped right in and sunk to the bottom. I could see the lights still blinking on the motherboard, so I pulled it out, dried it off with compressed air and started flying it again the next day. It still works just as terrible as it always has!
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