My helicopter tried to commit suicide!

[joe_kowalski]

I'm looking for input,

New 450 3gx. Finshed the build, finished the programming (upgrade to 3gx 2.0), spool-up test with tail wag (too much gain -- fixed), bladed holder too tight (fixed), I'm thinking everything is perfect. I install training gear (never know what to expect).

I charge the battery and set her out for a hover test.
Spool-up is rock solid, no vibrasion, no wag. Center stick (50% throttle and +1-2deg pitch).
I increase throttle / ptitch slowly and DO NOT TOUCH the cyclic.
just before lift off... she flips on her side in an INSTANT!!!

Post crash evaluation:

• destroyed main roter blades
• bent main shaft
• no other appearent physical damage, bench top testing seams otherwise normal

I have no clue what to look for after I repair the damage. I'm relatively sure its got to be in the 3gx, nothing mechanical failed as far as I can tell. Any ideas would be helpful.

Thanks,

[Martin353]

I hate to say it but I did that on more than one occasion when I was learning. It took me a while to realise that even with fbl I still needed to "fly" the beast ESP at takeoff. Have you got the settings on beginner and expo dialled in to soften the thumbs down?


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[joe_kowalski]

Not my first rodeo but I appreciate the reply. I always setup soft settings initially. I was prepared to make corrections but never had a chance. She never left the ground before it flipped over. Even the training gear didn't slow it down. Frustrating.

Thanks,

[SYMAWD]

Is it correcting in the correct direction?

[joe_kowalski]

In addition, This is my first FBL and the programming was a little intimidating. I'm assuming that I did something worng but I went over my notes again and everything looks right.

[joe_kowalski]

My correction settings were the first thing I checked in the post mortem. It was correcting correctly

[satgod]

u flying with s-bus or sats

I had issues with the 3gx and sats especially if your doing it on a 450 with the stock esc as the bec
you really need a seperate cc 10amp bec to be sure you dont have brown outs
3gx is very bad about it

my first brown out with a 3gx was my last, sold both units and will not use them again even though I get them for 99.00 nib I just WONT chance it

i'll fly zyx first

also go back thru the dir setup on the 3gx and double check everything

[Blade120]

Just upgraded my 450 v2 to version 2 of the 3gx software, it works pretty well... considering upgrading my other helis from 1.2 now. Theres a 15 min video from align on YouTube on the setup with version 2.0 pretty helpful..I would redo all the settings.During your maiden forget the training gear just pop the heli up in the air from a safe distance..

Sent from my DROID RAZR using Tapatalk 2

[joe_kowalski]

Thanks folks,

I'll go over everything again. I was hoping trhat there was an obvious answer. I guess I'll just have to start from scratch.

[mamartin]

Check for vibes too. You may need to change your mounting tape too something like 3M 411 tape or maybe you got vibes traveling down your wiring.
I've had this same issue with one of mine tipping just like you describe on take off.
It was due to vibrations effecting the flybarless unit

[SeanM]

I bet it's vibes that caused this to happen. The vibes will be magnified when it's on the ground. Once they reach a certain point, the FBL controller will not be able to stay oriented... which can cause it to make an unnecessary cyclic correction.

You mentioned that there were no vibes... how did you test for this?

[joe_kowalski]

I'm building a test stand to check the vibratons possibility. At spool up there were no visual indications of vibration but that doesn't mean that there wasn't high frequency vibs going on. I only had my eyes to detect vibs. One more thing to check.

One other comment was made by Satgod on using sattelites:

I'm running on 2 sats with direct connect to 3gx, no receiver. Everything else is stock out of the box.

Thanks Sean!
Thanks Satgod!

[aForcefulThrust]

My heli did this exact same thing when I upgraded from 1.2 to 2.0 on my 3gx unit. I thought it was correcting in the right direction, but it wasn't!

[bradg]

Is your swash level?
Check for level during the DIR portion of 3gx programming.

Swash turned off in tx?
Sticks at mid position?
Servo horns 90 degrees?
Use sub trims if needed.

After DIR portion you need to turn on swash in tx and set cyclic and pitch limits per the program instructions.
Do not use any trim after the DIR.
Good luck.

Brad G

[350Z_Al]

Most of the tip overs on first spool up are caused by the swashplate compensation direction of the gyro being reversed.

[SQRT(-2)]

Helis like to roll when they are light on their skids. Full size pilots have to worry about this too. You really have to watch it.

[Mike A.]

I would first suspect that the gyro was correcting the wrong way but you said that was fine, also check that your swash is following your sticks...left cyclic is left at the swash ect.

Since you said the corrections were right I bet it was a vibration problem like others have said. Did you balance your main blades? This is what I would do....once you have it put back together, before putting the main blades on spin it up. Hold onto the tail boom right at the tail gear box. Is there a high frequency buzzing vibration? If so then remove your tail blades...spin it up again while holding the boom again. See if that makes a difference.

I've had tail blades that are slightly out of balance cause some horrible vibrations. You can't really see the heli shaking but if you hold onto the boom you really feel it.

[hydro_pyro]

Every now and then, for some reason, the 3GX will fail to initialize properly at startup, and will behave like it's in DIR mode, with no correction at all. Make sure the blades are pulled out straight when you plug it in. Watch to ensure the swashplate jumps up and down 3 times and levels itself. Listen for the beeps, don't touch it till it finishes initializing.

When mine freaks ouot, the initialization will leave the swashplate tilted instead of level. The couple of times it did this and I didn't notice, it began to roll over when it got light on the skids. Both times, I caught it early and shut it down without damage.

[conejo]

hi,
the first thing that was upgraded in v2.0 is that you can correct your heli in takeoff. v1.2 has the tip over issue. +1 on reversed correcting direction.
Is your updated software correctly loaded? The heli changes from night to day.
It sounds to me that you are still in v1.2 due to the tip over issue.

[joe_kowalski]

Well here we go again! New blades, replaced bent main shaft and added pitch control arm turnbuckles. Bench test was fine and tracking was spot on.

Took it outside, spooled it up and started to increase throttle and pitch and WHAM! it happened again only in the opposite direction.

I'm convinced now that it's a vibration problem. I'm modifying my test stand from Dave Herbert's version to add a stable top plate for level spool up to test the theory.

I'll also check the V2.0 upgrade to make sure it's correct. I enjoy a challenge and actually like trouble shooting stuff that's complicated. It gives me a chance to invent other stuff to help me get at the problem. I'll keep you all posted.

Thanks again for your input folks.