500E first flight questions / 2 issues

[franklin_m]

Originally Posted by Gladius

Are you still using the stock tail gyro? That might be the source of the drifting you're seeing. You could buy a used Spartan Quark for ~$40-50, and that will really help your tail to feel locked in.

What kind of throttle curve are you running? Is it a flat curve, V-curve, or governor?

I'm using stock equipment, gyro is the GP 780. I'm using the general flight settings for throttle and pitch: throttle: 0-40-72-85-100; pitch: 0-5-12.

[andrea_farins]

I'm using the gp790 with 80% flat curve, spektrum tx (DX6 gen2, the black series), pitch -12/0/+12 or -5/0/+12, gyro gain near 68% and the tail is really solid. I put the gyro upside down under the tail boom support, it's better than the normal way in my opinion. did you try that?

I also thought to get a spartan few mounths ago and maybe it's better but I had other problems, my advice is to check and check again and then you'll find a solution, like I did. right now, for example, when I flown with up2 (throttle more than 85%) my tail is solid but happens some times it wagging really badly for a second when I'm ending a 8 figure or a normal curve in the air and then come back solid like a rock. but probably isn't a gyro problem, because it happened just when my throttle flat curve is more than 80%, maybe some vibration here and there, I need to check.

[Gladius]

I recommended a new gyro because of the drifting. A constant drift is commonly caused by a tail servo that's getting weak, or can't center properly; or a gyro that can't correct properly.

[franklin_m]

Just bought a Spartan Quark...should be at the house by the time I get off the business trip. Will update all.

If it turns out to be something else, then I'll use the align gyro as an experiment in plane!

- thanks again for the help

[Gladius]

Let us know if that works!

[franklin_m]

Will do.

[franklin_m]

Still not fixed. Here's update on troubleshooting:

- Tried two layers of 3m doubleside tape under GP790, no better

- Checked balance of tail blades - ok

- Spun up again on ground (no mains), as approached 2500 RPM, hard tail wag. On spooldown, after blades stopped, GP790 drove to stop despite zero RPM. Switched to rate mode, recentered, the back to AVCS and again drove servo to limit w/ zero RPM.

- Replaced gyro with Spartan Quark. Spun up, same tail wag as before

- Tightened tail belt, seemed better

- FYI, have same slop in grips as seen in this video:

Trex 500 tail blade grip slop (4 min 1 sec)

Any thoughts?

[Gladius]

Are you still using the plastic grips? If so, I HIGHLY recommend getting the V2 tail, or the i2rc tail. With slop like the video, it's going to be almost impossible to get a solid tail. Every time the tail unloads (which is every time the pitch changes from positive to negative), the grip will overcorrect, and the gyro can't keep up.

[franklin_m]

Originally Posted by Gladius

Are you still using the plastic grips? If so, I HIGHLY recommend getting the V2 tail, or the i2rc tail. With slop like the video, it's going to be almost impossible to get a solid tail. Every time the tail unloads (which is every time the pitch changes from positive to negative), the grip will overcorrect, and the gyro can't keep up.

If you could shoot me a link to correct part number / source for each, I'd appreciate it. I don't mind spending $$ to fix, just want to make sure what I buy is right thing.

Also, I'm still using the stock align servo horn, puts the distance from screw to ball a bit bigger than quark recommends.

[Gladius]

Here is the link to the Align V2 tail

http://m.helidirect.com/item/36373035

The i2rc tail is available from www.rc-tek.com

Here is the link.

http://www.rc-tek.com/store/i2rc-hig...hub-p2320.html

[franklin_m]

Awesome! I'm gonna go with Align parts, should I also buy the metal slider mechanism?

Frank

Originally Posted by Gladius

Here is the link to the Align V2 tail

http://m.helidirect.com/item/36373035

The i2rc tail is available from www.rc-tek.com

Here is the link.

http://www.rc-tek.com/store/i2rc-hig...hub-p2320.html

[Gladius]

Im not a fan of upgrading to metal parts, just because they're metal. I've found that plastic is easier to work on, because you aren't cleaning loctite off your bolts & screws every time you remove them. And metal parts are heavier than plastic a lot of the time. (High quality CNC'ed parts like what i2rc offers can be lighter than plastic though, so that's not a hard and fast rule.)

Align also offers a dual arm slider, which is supposed to be more precise, but I've actually had it cause a little bit of binding, because the force on the slider isn't applied parallel to the tail shaft. The older ball joint style slider doesn't have this problem, since the slider can rotate around the shaft. Newer models have a slotted ring around the tail shaft, and the pitch linkage has 2 pins that fit in the slot. This design gives the best of both worlds IMO, but I don't know of a way to get that option on the 500.

So, with all that being said, I wouldn't "upgrade" your tail pitch slider until you see if the V2 hub and grips fix your problem.

[franklin_m]

Originally Posted by Gladius

Im not a fan of upgrading to metal parts, just because they're metal. I've found that plastic is easier to work on, because you aren't cleaning loctite off your bolts & screws every time you remove them. And metal parts are heavier than plastic a lot of the time. (High quality CNC'ed parts like what i2rc offers can be lighter than plastic though, so that's not a hard and fast rule.)

Align also offers a dual arm slider, which is supposed to be more precise, but I've actually had it cause a little bit of binding, because the force on the slider isn't applied parallel to the tail shaft. The older ball joint style slider doesn't have this problem, since the slider can rotate around the shaft. Newer models have a slotted ring around the tail shaft, and the pitch linkage has 2 pins that fit in the slot. This design gives the best of both worlds IMO, but I don't know of a way to get that option on the 500.

So, with all that being said, I wouldn't "upgrade" your tail pitch slider until you see if the V2 hub and grips fix your problem.

Thanks again. I ordered the hub, don't know that it'll get here before I have to make another business trip, but I'll let you know how it works out. Also have one of the cyclic servos fail (elevator), thankfully on the ground. I'm going to call it an infant mortality issue, but since it's been in the box for two plus years, that just cost me another $50!

Frank

[SumOFparts]

You could give up cable.......

[Gladius]

Originally Posted by SumOFparts

You could give up cable.......

Already done! Don't miss it a bit.

[franklin_m]

Well, several weeks later, I finally found some time to work on the problem. Replaced the plastic tail grips with the pro metal ones, and replaced the bad servo. In the process, completely reworked the wiring, telemetry, etc.

I with no blades, can get to within 100rpm of max (2850) w/o any tail wagging.

I've also moved the rear rudder pushrod guide all the way back toward the tail, went with 3M gyro tape, and took some "preload" tension out of wires heading to the gyro.

Will try and fly in the next couple days.


Sent from my iPhone using Tapatalk

[franklin_m]

I just completed a rock steady flight! Thanks to everyone for the suggestions. In case anyone else is fighting the same issue, here's a list of what I did:

- Metal tail grips
- Loosened tail belt
- 3M gyro mounting tape
- Gyro mounted on top of tail boom
- Took some tension out of coiled wires heading to gyro
- Increased gain
- Used servo wheel instead of 4 arm