450 450 Clone Flybar Idle Up Malfunction/Implosion

[Bruno]

Don’t worry I own the AWESOME Trex 450 Pro V2. I love it!!

I have a STORM 450 from HeliPal with which I experiment.

I am just learning to fly so I use the clone to try new maneuvers.

Anyway, I set the WTF07H radio that comes with the Heli in Idle up mode with settings consistent with my Trex idle up mode settings.

Throttle Curve : NORMAL > -100, -66.7, -33.3, 0, +33.3, +66.7, +100
Throttle Curve : IDLE > -+100, +81.3, +64.0, +60.2, +64.0, +81.3, +100
Pitch Curve : NORMAL > -49.6, -26.7, 0, +25, +43, +73.8, +100, IDLE> default linear curve

I take her up in the air…no problem…flip the idle up switch and the Heli basically implodes in midair.

The swash guide broke, the shaft bent to almost 90 degrees, knocked the Canopy off, battery off…it was horrific. Upon examination all I could come up with is that when I switched to idle up the swash guide broke and the Heli tore itself up.

Anyone have any ideas what may have happened otherwise?

I wish I had video of the implosion.

I have rebuilt the Heli but I am hesitant to give it another try until I get some feedback.

Please laet ne know what you think.

Thanks.

 

[Tony]

It could have been a number of things from feathering shaft bolt to a bad blade. However, your "normal" T-Curve should start with 0, not have it in the center. Just wondering how you are making this work...

 

[zenmetsu]

Yeah, and negative throttle? I thought that throttle was always positive and the pitch was negative, even then most radios show a percentage that is positive and 50% equates to zero pitch.

Throttle Normal would be 0/25/50/75/100
Throttle IdleUp would be like 100/90/75/90/100

Pitch curve should be like -2º, -2º, 0º, 5º, 10º in normal, and -10º, -5º, 0º, 5º, 10º in idle up.

The numbers you post don't make sense to me.

If I had to take a wild guess as to what happened, I would say that you were hovering, and based on your numbers from what I could tell, you may have been at or just above mid-stick on the collective. This would have put pitch at about +25% and the throttle at about 50% if I read your numbers correctly. When you flip idle-up from this position, it looks like your pitch would have dropped to zero with a "default linear curve", and the throttle would have been increased to the 60% level or higher. With a neutral blade pitch, I guess that it is possible that the head could have been over-revved and this would explain the shaft bending if something wasn't balanced correctly.

 

[Bruno]

With the WFT07 radio that came with this heli -100 on the graph is equivalent to 0 throttle. 0 on the graph is equivalent to 50% throttle.

 

[Tony]

Okay, that makes sense then lol.

 

[Bruno]

Yeah, and negative throttle? I thought that throttle was always positive and the pitch was negative, even then most radios show a percentage that is positive and 50% equates to zero pitch.

Throttle Normal would be 0/25/50/75/100
Throttle IdleUp would be like 100/90/75/90/100

Pitch curve should be like -2º, -2º, 0º, 5º, 10º in normal, and -10º, -5º, 0º, 5º, 10º in idle up.

The numbers you post don't make sense to me.

If I had to take a wild guess as to what happened, I would say that you were hovering, and based on your numbers from what I could tell, you may have been at or just above mid-stick on the collective. This would have put pitch at about +25% and the throttle at about 50% if I read your numbers correctly. When you flip idle-up from this position, it looks like your pitch would have dropped to zero with a "default linear curve", and the throttle would have been increased to the 60% level or higher. With a neutral blade pitch, I guess that it is possible that the head could have been over-revved and this would explain the shaft bending if something wasn't balanced correctly.

The numbers you post are pretty much how I have my Dx6I. The WFT07 radio numbers use negative to represent any setting below 50%. I set the pitch using a pitch guage and settings similar to the ones you posted.

- - - Updated - - -

Yeah, and negative throttle? I thought that throttle was always positive and the pitch was negative, even then most radios show a percentage that is positive and 50% equates to zero pitch.

Throttle Normal would be 0/25/50/75/100
Throttle IdleUp would be like 100/90/75/90/100

Pitch curve should be like -2º, -2º, 0º, 5º, 10º in normal, and -10º, -5º, 0º, 5º, 10º in idle up.

The numbers you post don't make sense to me.

If I had to take a wild guess as to what happened, I would say that you were hovering, and based on your numbers from what I could tell, you may have been at or just above mid-stick on the collective. This would have put pitch at about +25% and the throttle at about 50% if I read your numbers correctly. When you flip idle-up from this position, it looks like your pitch would have dropped to zero with a "default linear curve", and the throttle would have been increased to the 60% level or higher. With a neutral blade pitch, I guess that it is possible that the head could have been over-revved and this would explain the shaft bending if something wasn't balanced correctly.

I am thinking about your explanation.....so, according to your numbers, while in idle up and at mid stick, pitch would be 0 and throttle would be at 75%, correct? Since I was hovering (maybe +3 pitch) probably at about mid stick in normal mode before I switched to idle up my pitch (with a linear curve would have been about +3) should have been a smooth transition, no?

- - - Updated - - -

Okay, that makes sense then lol.

Yes, it's an odd radio. If I keep this heli much longer it will make since to install a spectrum receiver.
Question: do I have to switch to idle up to do simple moves like back flips, forward flips and rolls? Could these moves be done easily in normal mode ?

 

[murankar]

Yes, any time you go inverted you need to be in idle up mode.

 

[Bruno]

Since I am waiting on the swash guide (which was destroyed during my switch to idle up “IU” mode) the motor is off the frame. So, fired up the motor and watched the swash as I switched from normal to IU. I had the radio set so I could confirm mid stick. When I switched to IU the blades went to a negative pitch from maybe +4 to -5. This is probably what happened during flight causing an abrupt change in pitch and bending the shaft. I adjusted the throttle curve so that when at mid stick and I switch to IU there is no change in pitch. In other words, it stays at about +4. However, this is no longer a linear pitch curve during IU.



Is this OK?



I have often read that in IU you should be set to a linear pitch curve. However, (repeating what I wrote above) compared to my normal mode pitch at mid stick when I switch to IU it will bring the Heli down.



I welcome any and all input.



Thanks.

 

[zenmetsu]

I am thinking about your explanation.....so, according to your numbers, while in idle up and at mid stick, pitch would be 0 and throttle would be at 75%, correct? Since I was hovering (maybe +3 pitch) probably at about mid stick in normal mode before I switched to idle up my pitch (with a linear curve would have been about +3) should have been a smooth transition, no?

Maybe.
Pitch Curve : NORMAL > -49.6, -26.7, 0, +25, +43, +73.8, +100, IDLE> default linear curve

This gives -49.6/-26.7/0/25/43/73.8/100 (NORM) and -100/-67/-33/0/33/67/100 (IDLE UP) if the linear curve is correct. If you were hovering, you would have been at mid stick or higher. For the positions listed, these would be the transitions when you change modes: 0 > -33, 25 > 0, 43 > 33, 73.8 > 67

These could be correct, I have no experience with inverted operation other than doing really messy tick-tocks and aileron ticks in the simulator. I was just trying to find an explanation for your head detonating like that. I'm one of those people that seriously dislike being unable to find a root-cause for a given failure. In my case, I wouldn't even fly again until I was reasonably satisfied with an explanation for the crash.

- - - Updated - - -

Oh, I didn't read your second post. It sounds like you may have found the problem. When you look at the numbers I posted, you can see that your pitch will always decrease while switching from normal to idle up. +4 to -5 seems a bit extreme, but it could have happened.

My pitch curve is 50/47/50/75/100 and idle up is 0/25/50/75/100. The takeaway is that from midstick and up, the pitch curves are identical. You list your "PITCH" curve as being -49.6/-26.7/0/25/43/73.8/100. The negative side seems a bit excessive for normal flight, but you could probably avoid a major jump in pitch by changing this to -49.6/-26.7/-13/0/33/67/100 since mid stick would be zero, and everything above would be linear to match.

I'm sure Tony will jump in with some useful pointers.