First IdleUp hover results in crash

[AtomicFlyer]

So I thought I'd try IdleUp hover for the first time this evening. I set the IdleUp throttle curve for 80% flat across. I spun up the rotor in normal mode to half throttle, then switched flight mode to IdleUp. The heli yawed a little on the ground when the motor sped up (as I expected) but everything seemed correct. I increased collective and hovered a few feet off the ground. But the heli started to yaw. I decided to bring it down but the yaw increased and it crashed on landing (blades, main and feathering shafts, 2 servos stripped).

So I'm wondering, do you guys use different gyro settings for IdleUp vs. normal? I'm running the stock gyro and servos.

Marc

EDIT: Also just noticed that my belt is quite loose. I guess I could have been skipping teeth? Didn't sound funny though.

[Roger_15]

Sucks, don't it? I crashed too on my first attempt at idle-up...well, more of a tip over for me. The ground I was flying off of wasn't level. Also, I hadn't planed to do it; instead, my son harassed me into it. I couldn't resist.

But the good news is, I fly with the heli in idle-up all the time now, it really is better so keep at it.

Good luck.

[Slyster]

Here's what I do.. my normal curve is 00-60-70-80-90 and idle up curve is 85-83-80-83-85 See what happens then?

In normal mode once I get airborn I'm around 80! So idle up is nothing new when you switch to it. In fact you can make both pitch curves the same too if you want to ease into it.

I slowly bumped my normal throttle curve up 5 each day.. so I gradually worked up to 80's and above.

[blahblah9]

yea if you switch on the ground at mid stick the motor will jump up in speed and the taiil will kick some. if you switch in mid flight u can't really even tell you flick into 3d mode. now that being said, i like to do it on the ground so i can hear the motor increase and know 100% its in idle up LOL when i did it in the air i was like i dunno if it went into 3d mode or not so i had to land to check LOL i didn't wanna do a flip to find out she wasn't in idle up

[Mon_t]

Sounds like the belt came loose from the jump in rpm after flicking the switch.

I had the same problem with my trex 500 as I didn't have the bolts holding the boom tight enough. This also resulted in a crash (luckily I got away with just a couple of broken zip ties and some bent landing skids)

To avoid this, use a servo boom mount butted up against the frame.
Also start in idle-up using the soft start feature of the esc.

[reALIGNed]

Why not just spool up from idle up position and begin flying?

[rockjock3]

Were you counteracting for the normal heli tilt. It will tilt, and keep tilting to the left if you don't give it a little right collective. It is normal for the a heli to pull to the left due to the spinning of the blade and rotor. Normal stable condition in a hover is the heli leaning slightly to the right ~5 degrees. Sounds like you didn't counteract that.

[AtomicFlyer]

Originally Posted by Mon_t

Sounds like the belt came loose from the jump in rpm after flicking the switch.
...To avoid this, use a servo boom mount butted up against the frame.
Also start in idle-up using the soft start feature of the esc.

Yes, that's a good idea (assuming the problem is a slack belt as I suspect at the moment). Thanks for the hint Mon_t

Originally Posted by rockjock3

Were you counteracting for the normal heli tilt. It will tilt, and keep tilting to the left if you don't give it a little right collective. It is normal for the a heli to pull to the left due to the spinning of the blade and rotor. Normal stable condition in a hover is the heli leaning slightly to the right ~5 degrees. Sounds like you didn't counteract that.

The heli was actually already hovering a few feet off the ground for 10 seconds or so. It was in a pretty stable hover. My problem was actually yaw (rotating around the axis of the main shaft).

So I guess there is either something peculiar about IdleUp that caused the heli to yaw after 10 seconds or so of stable flight, or the belt was skipping teeth because it is certainly more loose now than it was before. I'll try Mon_t's suggestion of a clamp on the boom to prevent it from slipping further into the frame.

Oh well, nothing that about $20 and a couple hours of my time won't fix!

Marc

[jockstrap]

I'm not sure what transmitter you have.. I have a DX7 for my T-Rex's (but don't have a blade 400)..

On the DX7 - you can set different gyro gain values for normal, idle-1 and idle-2

If your transmitter is similar - make sure your gain is the same or a tiny bit higher on the idle-up as compared to the normal setting..

Just maybe your gain on idle-up took the gyro out of HH mode ??? Just an idea..

Also - i would not even attempt using idle-up till you can hover quite well, then hover to about 4-6ft high or more and enter idle-up.. this way you have time to react, if you are sufficiently good at hovering, you should be able to compensate the yaw should it happen again and then switch back to normal mode.... if you can't, you probably need more hovering training...

Also - try to take note of where your pitch stick is at hover and then examine your pitch curve for idle-up at that stick position. Ideally, when you want to switch from normal to idle-up, you don't want any change in pitch - just a bit more headspeed... if your pitch curve changes at that stick position, it could result in the heli falling or shooting up...

When i hover my t-rex and enter idle-up, the heli does not change altitude, it merely increases headspeed.

not sure if any of these are the cause of your problem - but hope they help!

My pitch curves (5 positions) are:

Hold: 40, inh, 50, inh, 100
Normal: 40, inh, 50, inh, 100
Idle-1: 0, inh, 50, inh, 100
idle-2: 0, inh, 50, inh, 100

Where inh = inhibited or turned off - so basically acts then like a 3 point pitch curve.

These curves will ensure any pitch above mid-stick matches between normal and idle-up modes and you wont have any pitch issues... they should be more than adequate untill you are an advanced 3D pilot!

[Dazz]

Originally Posted by AtomicFlyer

So I thought I'd try IdleUp hover for the first time this evening. I set the IdleUp throttle curve for 80% flat across. I spun up the rotor in normal mode to half throttle, then switched flight mode to IdleUp. The heli yawed a little on the ground when the motor sped up (as I expected) but everything seemed correct. I increased collective and hovered a few feet off the ground. But the heli started to yaw. I decided to bring it down but the yaw increased and it crashed on landing (blades, main and feathering shafts, 2 servos stripped).

So I'm wondering, do you guys use different gyro settings for IdleUp vs. normal? I'm running the stock gyro and servos.

Marc

EDIT: Also just noticed that my belt is quite loose. I guess I could have been skipping teeth? Didn't sound funny though.

I had the same problem and found that my belt was loose ..............the more throttle I gave it the more is slipped the more it span ........after tightening you should not be able to push the belt more than half the width of the boom .....any tighter and the engine screams .......Check the belt with a hex wrench to avoid damage

[AtomicFlyer]

Originally Posted by jockstrap

...Just maybe your gain on idle-up took the gyro out of HH mode ??? Just an idea...

Also - i would not even attempt using idle-up till you can hover quite well, then hover to about 4-6ft high or more and enter idle-up..

When i hover my t-rex and enter idle-up, the heli does not change altitude, it merely increases headspeed...

These curves will ensure any pitch above mid-stick matches between normal and idle-up modes and you wont have any pitch issues... they should be more than adequate untill you are an advanced 3D pilot!

Thanks for the tips Jockstrap! I appreciate the detailed reply. I bought the RTF version of the Blade400 so it comes with the DX6i. The radio only has two flight modes, normal and idle-up. And it has a separate switch for two different gyro settings. (do gyro settings change automatically on the DX7 when you change flight mode?) I was at gain of 78%, which is the HH mode I always fly in when I switched to Idle-Up.

I'm actually able to hover very well in all orientations (nose-in all day long) and I fly decent fast forward. But yes, this was the very first time I tried Idle-Up.

When I switched to IdleUp on the ground, the head spead did increase but since I was at mid-stick, the pitch didn't change and the heli didn't leave the ground at that time. (It did yaw about 30 degrees on the ground though)

I did confirm that at half throttle stick, both of the pitch curves are at 50%, which is zero pitch at my setup.

Originally Posted by Dazz

I had the same problem and found that my belt was loose ..............the more throttle I gave it the more is slipped the more it span ........after tightening you should not be able to push the belt more than half the width of the boom .....any tighter and the engine screams .......Check the belt with a hex wrench to avoid damage

During the rebuild, it was very obvious that the boom had slid back into the frame. I could hold the tail rotor and spin the main gear and make the belt slip very easily. The only question left in my mind is did IdleUp cause the boom to slide back into the frame, or did the crash cause that! Which came first, the chicken or the egg???

I loosened the boom screws and adjusted the belt tension as you mentioned Dazz. I don't have a spare tail servo mount to use as a lock collar on the boom as Mon_t suggested, so I'm going to put some tape around the boom to prevent it from sliding back into the tail again.

The rebuild is done but it looks like one or more of my ball links got bent so one blade pitch is messed up. I'm going to fix that this morning and give it another whirl!

Thanks for your help guys.

Marc

[AtomicFlyer]

I got everything set up and just hovered a pack in IdleUp. So as a couple other guys suggested, my problem was a loose belt. After adjusting the belt tension, I painted a little bit of White-Out on the boom right where it enters frame so I could tell if it starts creeping back into the frame again.

My permanent fix will be another tail boom servo mount used as a clamp as suggested earlier in this thread.

Thanks again.
Marc

p.s As nothing is ever that easy, I spent an hour chasing what appeared to be a really bad tail vibration. So bad that I couldn't fly. Well, it wasn't the tail at all. It was one main blade a couple of degrees off pitch.

[jockstrap]

good stuff - glad you got it sorted...