300X Tail Wag Compendium

[tjkennedy]

After fixing MANY tail wag issues (and documenting them) I have put together what I call the "300X Tail Wag Compendium".

This is Rev 3.0 of the document based on some good input from others in this thread.

If you have additional ideas / tips / corrections / etc. please post them and I will update this .PDF to a new revision and repost it.

Also, if anyone wants this document in a Microsoft Word format just send me a PM and I'll send it back to you.

I hope this helps someone as I've struggled with tail wag over and over.

[KiloXray]

Nice write up!

Another thing that applies to guys running aftermarket ESCs, is the relationship between governor gain and gyro gain. You can get a little wag from there as well. You will need to find the highest level of them both combined to keep the wag at bay. This may take a bit of trial and error to find a good combination.

[DoubleCH]

Nice work gathering the essentials in a writeup. Some of the statements sound familiar.

A few points to add:
- installing tail hub onto tail shaft: make sure tail shaft does NOT stick out of tail hub end or else you won't get enough max right rudder pitch
- installing tail grips and blades: tail blades run up against rotor wash which means forward facing blade goes up, 300X is leading edge control which means grip ball is always on the blade leading edge side
- checking belt twist: without main gear or mainshaft in place, stretch the belt with a finger in the same orientation as the tail shaft. If tail rotor rotates in opposite direction when you rotate finger, the belt has twisted 180 degrees; otherwise, feel for notchiness as you rotate finger which indicates belt twisted 360 degrees.
- tail pitch arm lever doesn't have to be perfectly 90 degrees to the pushrod, but you want tail servo arm to be 90 degrees to pushrod to have the most mechanical gain at servo natural center and now the next point is even more important
- rate mode adjustment: set gyro to rate mode with gain = -30 (-100 to 100 scale TX, or set to 35 with 0 to 100 scale TX) and only be activated with gyro switch. Flip into rate mode on the ground and make sure servo arm is 90 degrees to the pushrod. Then, take heli into hover in HH mode with whatever gyro gain you've been running before and then flip into rate mode in the air (-30 or 35 as mentioned above). If heli rotates CW viewing from top down with no rudder input then lengthen pushrod, and vice versa until heli doesn't rotate with no rudder input. Once tuned you'll notice with no rudder input in rate mode servo arm is still 90 degrees (servo natural center) to pushrod but tail blade leading edge is pointing a bit towards boom. This setup is better than having zero pitch at servo natural center because it helps prevent gyro play catch up while correcting drift and can mitigate different kinds of tail wags and/or stop bounce.
- setting rudder and tail sensor directions: set former on TX under servo reverse section and set latter in BX "setup F" as you mentioned. Whenever you change to a different servo or its mounting orientation that requires changing TX servo reverse, you'll also need to change setup F. The only situation that involves changing one but not the other is when your setup change involves changing BX mounting orientation.
- rule of thumb for tail thrust direction: tail blade leading edge ALWAYS points to the direction the tail blades want to push the tail (e.g. if tail blade leading edge is moving towards boom whether from rudder input or from you rotating the heli, tail blades will be pushing themselves towards boom while the heli is hover in the air).
- fine-tuning BX for tail performance: know the difference between the different available settings...
https://www.helifreak.com/showthread...58#post5080158

EDIT: tried to correct as many grammar/spelling mistakes as possible. If you find any of these points useful, feel free to use them and change the wording whichever way you like. I try to focus more on providing (hopefully) good info than to focus on my grammar/spelling. Apologize to those who find these frustrating to read, but OTOH appreciate if these can be put to good use if found useful.

[John66]

Great thread. Can we get this put in as a STICKY????? PLease

[tjkennedy]

The .pdf has been updated with suggestions made above.

[GSPI]

Yes excellent information. I agree this should be a sticky.

[helibus]

Great start - thanks for the initiative. Apply or ignore the following suggestions as you see fit. Some of these comments are based on the fact that for some readers, English isn't their primary language. Statements need to be as clear and concise as possible. If someone gives you some text to use, scrub it.

• Remember that you'll only be able to edit the thread title and your first post for a short while. You may want to keep the version number out of the thread title.
• Adding page numbers, section numbers, and/or figure numbers would help people be able to reference specific parts of the document
• Consider adding your HF user name to hinder someone from reposting the document as their own. You deserve the credit.
• Consider capturing a revision level and/or date in the document text
• Consider adding a references summary that has links to things like the BX manual, and reference people to this thread for posting comments or checking for updates
• The purpose of the document is a bit confusing. There's some good, basic setup info, but not all of it ties into solving tail wag. For example, clarifying blade rotation, tail thrust direction, etc. is important but I wouldn't expect to see it discussed as a way to solve tail wag. Maybe the basic setup stuff could be grouped into a major section or appendix called "basic things to check" or moved into a separate document where lots of other good stuff also unrelated to tail wag could be captured.
• Tail pushrod servo linkage connection: To nitpick, I'd start the statement with "At the tail servo...". End of the sentence should read "of the servo horn". How does one "make sure" the ball link position isn't too far out? Maybe just reword that sentence to "There will be excess mechanical gain that can lead to wag if the connection on the servo arm is too far out".
• Belt tension: Can someone come up with a way to improve on Blade's subjective hex driver test? After all, you could probably push the hex driver through the belt and other side of the frame if you just push hard enough. I know the feel comes with experience - just wish there was a way to describe it better.
• Tail blades: for completeness, a reference on balancing the tail blades would be good. If nothing else, John Salt (rchelicopterfun) has a pretty good description with pictures on how to do this for the 130x. The concept would apply here.
• Rule of thumb for tail thrust direction: I pity the reader who struggles with English.
• Tail Rotor Pitch Lever: "...now the next point is even more important" seems superfluous. What next point? The next section on greasing the pitch slider? Doubtful.
• Tail sensor direction: On bullet 3, do you mean "turn the helicopter nose to the left"? Moving the entire helicopter sideways to the left likely wouldn't cause a rotational movement in the tail blades. Words following bullet 5 are meant to be part of the sentence for bullet 4. Why bother including the status LED color box here? It doesn't add anything but confusion. For example, the factory setting shown is for the native BX default, not the 300x default.

[Nytro97]

I want to thank everyone for sharing this information. I have had no tail wag and my 300x has flown perfect for many many flights. It has not chased a worm into the ground yet either.When that day comes I'm sure this info will come in handy.

Tom

[darowden]

I have one on the way, I cannot thank you enough for posting this information.

[mgfiest]

what I thought was a minor crash became a big fix... had to take a lot apart to do those little damages... in a nutshell... major tail wag... have download this pdf and will see if it will help me get rid of the wag

[LethalSassonic]

The Microheli longer tail boom-support brace helps stabilize the tail, it's longer and more robust, I flew with and without it two days in a row, and it for sure makes a difference, the hover is more stable, and the overall flying is more stable. And run the belt on the tight-side, the heli flies more stable. I did those two things, and I feel almost zero vibs, no wobble, and have more confidence to take command of the sky