Porpoising?

[Staticxd00d]

I know this isn't the best quality video... but it seems like my new Nano CPx is porpoising a lot... like, in the sim I can keep the helis pretty much in a hover in one spot, but this thing I get it stable and let go of the sticks, and it sits there for a second, then kinda acts like something else tells it to move off in one direction. I kinda feel like I'm fighting it all the time. Thoughts?

Blade Nano CPx tail wagging and porpoising (3 min 17 sec)

[Russell Harding]

Looks normal to me.

The nano is really small and tiny air drafts and rotor wash has a lot of effect on stability.

It is hard to tell from your video, but 'toilet bowl effect' is a solvable cause of nano instability. Read up on the symptoms, it is a circular precession in hands off hover. On the nano it is usually caused by a too tight feathering shaft. I ran mine with a bit of play in the head and CA on the nut to keep it from loosening.

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[Staticxd00d]

The toilet bowl effect is EXACTLY what I'm seeing... I will look into that.

Thank you!

[JonJet]

TBE can also be caused by a cracked main shaft

[Staticxd00d]

Main shaft feels very solid to me... I'm not detecting any cracks.

Ok... so how on earth do I loosen the feathering shaft???

[mtchristman]

If you got it new it should have came with two identical tools for the feathering shaft. Pull your main blades off and you can see the little nuts that the tools go on inside the blade grips.

[Boeingpete]

For TBE, for sure you want to check the feathering shaft, but don't go mad when loosening the nuts. Maybe only needs a half turn or so. Also, with due deference to your flying skills the landings sound pretty firm to me, so worth making sure the main gear hasn't slipped down the shaft. It doesn't take much to make it move. Trust me I speak from experience.

Having said all that it looks pretty healthy to me. The Nano is real squirrelly, and at only 29 grams it only needs the slightest breath of wind or its own wash to unsettle it. This thing will never fly hands off for very long no matter how well trimmed and rigged it is. You have to fly it ALL the time, which is what makes it a great trainer.

[Staticxd00d]

Loosened the feathering shaft 1/2 turn. Just went out and put 4 batteries through it... and it's like a different heli! It is still doing the toilet bowl thing, but not nearly to the extent it was. Is it safe to assume another 1/2 turn on the feathering shaft might eliminate it altogether?

I even flipped off the dual rates and flew it at 100% with 30% expo for the last battery. Was able to control it MUCH better than before. Even had it in a hands-off hover for a few seconds a couple of times.

[Russell Harding]

Looser is better.. Until it comes unscrewed and a blade flys off. Secure the nut with something and back it off.


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[nickyd]

Loose so you have about half mm play when push pulling blade grips is perfect for me.
Hovers hands off 2 or 3 seconds.

[Staticxd00d]

Loosened it another 1/2 turn. Swapped and put the bullet blades on it. Vast improvement! It's MUCH more controllable now! Thank you guys again for the help!

[ToddMcF2002]

30% Expo might be causing you to over correct contributing to TBE. Try 15-20%. 30% will also have you heavy on the sticks, especially elevator causing porpoising in forward flight. Practice keeping the Nano level doing small figure 8's (20 foot box) and you'll refine your stick work. Keeping a nano level in a figure 8 is fantastic orientation work and teaches fine stick control.

The other big difference vs. sim that I'm sure you've noted is that the Nano needs constant pitch adjustment like you are doing in your vid. The thing wants to either rise or hit the deck. It will do this indoors in a gym too. The brushed motor contributes to that. The factory brushless upgrade is much easier to keep at a level elevation as its pitch control is responsive. Higher and constant RPM makes it more stable. Constantly correcting (and over correcting) for pitch is distracting when you are trying to learn orientation.

Sorry for babbling & preaching unsolicited. Just trying to help.

[Staticxd00d]

Originally Posted by ToddMcF2002

30% Expo might be causing you to over correct contributing to TBE. Try 15-20%. 30% will also have you heavy on the sticks, especially elevator causing porpoising in forward flight. Practice keeping the Nano level doing small figure 8's (20 foot box) and you'll refine your stick work. Keeping a nano level in a figure 8 is fantastic orientation work and teaches fine stick control.

The other big difference vs. sim that I'm sure you've noted is that the Nano needs constant pitch adjustment like you are doing in your vid. The thing wants to either rise or hit the deck. It will do this indoors in a gym too. The brushed motor contributes to that. The factory brushless upgrade is much easier to keep at a level elevation as its pitch control is responsive. Higher and constant RPM makes it more stable. Constantly correcting (and over correcting) for pitch is distracting when you are trying to learn orientation.

Sorry for babbling & preaching unsolicited. Just trying to help.

Please... do not apologize! I appreciate any and all help anyone is willing to give!

I am definitely considering the BL upgrade... though after loosening the feathering shaft and changing to the bullet blades, it really is flying a LOT better. I just hovered it in the kitchen this morning with 4 batteries, and it flew great. I will drop the expo a bit and see if that helps. I do have to constantly stay on the pitch to try to keep it where I want it, hearing that the BL upgrade helps with that makes me smile.

I'm also considering the Lynx stretched boom and blades upgrade... any thoughts on that?

Thank you again for your help!

[Staticxd00d]

FYI - I dropped the expo down to 20%, and that did help! I've flown a dozen batteries through it today, having a blast!

[JonJet]

Originally Posted by Staticxd00d

I'm also considering the Lynx stretched boom and blades upgrade... any thoughts on that?

Thank you again for your help!

My suggestion would be to have one of HF's Heli Guru's do a complete brushless conversion...twice the price, but 10 times the performance