500 Derek's Align Trex 500

[Derek]

I thought I had a specific thread for my 500. I have several threads about various issues that I've had, lol. So...Here is a specific thread for my 500.

I have noticed, over the last 10-13 flights that my 500 is acting a bit odd. It hovers and flies just fine, with the exception of a bit of a lean to the right....constantly. I can get over that because I think all heli's lean to the right a bit (or maybe it's a lean to the left, but mine leans to the right). Another problem I've been experiencing is when I am inverted and I go vertical, the helicopter will roll to my left. So, picture this.....nose in inverted hover and then punch out hard....it rolls to my left side....as if I were giving right aileron input. I've checked and double checked that the swash is level. I've checked that the servos are all traveling the same, etc, etc.

So...since it's about due to an inspection anyway, I'm going to tear it down and start all over. Which also means that I'll be back here soon posting questions about what I screwed up, lol.

Anyway...this should be fun!!

 

[stokke]

Will it do the same if you're right side up, then punch the negative collective (or positive collective for that matter)?

 

[pvolcko]

Okay, so upright you need to lean it a bit right in order to counteract the tail wash effect. Inverted nose in it will have to be leaned a bit right too for the same reason. When you flip from upright leaning right to inverted it will naturally be leaning a bit to the left until you stabilize the hover. Then when you punch out the heli needs to crank up the tail pitch to keep it from yawing under the torque load, thus increasing the tail wash effect. If you are not actively leaning the heli into that effect during the punch out, it will appear to drift left. The roll may simply be too low a cyclic gain setting so it isn't maintaining cyclic attitude during the manuever, especially in concert with the increased tail wash.

Just some immediate thoughts. May be totally wrong.

Also, is the swash level throughout the full min to max sweep of the collective? Or does one side drift a bit near min or max? If it is drifting toward min collective then that may explain it too, again coupled with a too low cyclic gain setting.

 

[Derek]

While the 500 is upright, I can go full positive and the helicopter will go straight up and the tail holds solid. While the 500 is inverted and I go fully negative, the helicopter will roll as if I am giving right aileron....it rolls to my left, in a nose in orientation. The tail holds solid. It's got to be something with the travel limits, on the negative side, right? My 500 is still flybarred, also, so there isn't a cyclic gain adjustment.

 

[Derek]

Here is a bit of video that demonstrates what's happening...

Trex 500 Flybarred inverted "Roll" issue - YouTube

 

[danhampson]

Was the swash leveled at low centre and high stick?

Like you say in your video it could be a travel issue.

 

[Tony]

either travel, or you have some play somewhere.

 

[Derek]

I believe so, yes. That's why its confusing. Maybe I need to fasten the helicopter to the ceiling, so that's its inverted, and then recheck it with the swash tool, lol.

This is why I'm just going to start over from scratch. I'm not gonna delete the 500 profile from my DX8, because it does fly. I'm just gonna start a new profile and just try to figure it out.

 

[Tony]

No need for all of that. Just grab the blades and move them like the servos would. Find the slop. My 450 SE V2 has this same issue. Flies GREAT when upright, but once you flip it inverted, it's all over the place. ,

 

[Derek]

I'm at work right now but I'll check on that in the morning. Thanks Tony!

The more I've thought about it, starting an all new profile is probably a waste of time. I'll move the blades and see if I can find any slop in the linkages. If not (hopefully not) I'll go through and recheck the entire head. I really hope its something simple.

 

[Lee]

Also check your side to side CG.
If its off to one side, the fact that the weight of the heli is above the disc when inverted, a slightly off CG can cause a huge effect.

 

[Graham Lawrie]

Sounds like it could be play in your links another thing I found in mine was slight lift on the main shaft which in normal orientation was fine, inverted the shaft would drop

 

[Derek]

I just got home from work. Thanks for all the suggestions!

I checked my side to side cg and, even with the stock 70amp esc mounted on the right side of the frame, the cg is good.

I held the helicopter down at the landing skids and pulled up and pushed down on the head. No slop there. I did, however, find a couple of things. There is some slop in the swashplate, itself...and I noticed that my flybar is 0.31mm longer on one side than the other but the side of the flybar that is shorter falls. It's a bit difficult to describe in text so I have a video uploading to Youtube right now. The video will show both questionable issues.

 

[Derek]

Ok, here's the video that shows what I found this morning.

Trex 500 inverted roll issue Part 2 - YouTube

 

[Slobberdog]

Derek when you held one grip and twisted the other to me it looked like your swash follower was twisting on the head block pins, and the swash was only moving because of that twist

 

[pvolcko]

I think the earlier suggestion was to fly it, climb up pretty high and then do a full negative descent to see if it skews or rolls in the same way it does while inverted.

Since this is FB, def check swash level at full collective throws and adjust accordingly.

 

[Powerdyne]

Maybe check the weight of your flybar paddles against each other. One may be lighter than the other. With the Flybar falling like that on the short side, It could be that even though the long side isn't falling, the paddle itself is either a bit further out, or a bit heavier than the other on the longer side. This could be causing that issue. Try taking off the paddles, and checking their weight, and also adjust that flybar to get it as close as centered as you possibly can.

As for the swash movement like in the video, Slobberdog has pointed out that the washout base and follower arms look to be causing the movement. I would agree. I would say remove the swash, and chack to see if there is any up and down play, or wiggle. It could be that your swash is worn in, and the top is rocking a bit.