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View Full Version : Paging Dr. Mcallister, Pops up on take off


snowball75
08-28-2011, 11:16 PM
When I spool up and RPM's get rolling, the heli pops up instead of a smooth take off. I was testing in my basement and almost hit the ceiling. I'm running a 450 with SK720, CC Ice 50, and Scorpion 2221-8 motor.

Also, right before it takes off, it looks like it's tilting to one side.

What should I be adjusting? Thanks.

mhoebrec
08-29-2011, 01:50 AM
Looks like an issue with your pitch curve.

The tilting could could be caused by vibrations. Have you checked the playback/vibration log?

Windbreaker
08-29-2011, 04:04 AM
I'd suggest not doing test flights indoors. Too much potential for things to go wrong.

I can understand tying it down to check for spool-up, checking RPM's, etc. But to actually fly, you really should give yourself the safety margin of an open sky and broad space.

Because when testing something like this, you need to be prepared for a runaway. Recovery takes time and, therefore space.

Luckily you have very fast reactions!

georgi UK
08-29-2011, 04:12 AM
=] yes we need to look at the pitch curve and how you achieved it. what are the values for the 60/60/45 swash mix & what head conversion are you using? also, have you set the stick scaling in the utility tab?

the aim is 12 deg +/- when setting up, for normal mode reduce the Tx end points to give less pitch range for hovering.

zeeflyboy
08-29-2011, 05:16 AM
Also check linkages are smooth and free... Sticky links often cause jumpy collective.

rceccleston
08-29-2011, 05:33 AM
=] yes we need to look at the pitch curve and how you achieved it. what are the values for the 60/60/45 swash mix & what head conversion are you using? also, have you set the stick scaling in the utility tab?

the aim is 12 deg +/- when setting up, for normal mode reduce the Tx end points to give less pitch range for hovering.

I'm sure you'll agree, once you've re-read your post, all CCPM mixing that affects the pitch, elevator and aileron travel should be done in the Skookum.

Else, the Skookum could cause binding during flight and eventually cause a servo to burnout.

When I spool up and RPM's get rolling, the heli pops up instead of a smooth take off. I was testing in my basement and almost hit the ceiling. I'm running a 450 with SK720, CC Ice 50, and Scorpion 2221-8 motor.

Also, right before it takes off, it looks like it's tilting to one side.

What should I be adjusting? Thanks.

In response to your problem, on the 'swashplate' tab, you should adjust your 'collective pitch' to obtain 12+/12- with 100+/100- travel in both your transmitter and Skookum.

Once, you have completed the above, use a normal pitch curve of 40-45-50-70-90 for soft landing and responsive collective management.

Also, I recommend 110 deg/sec for both elevator and aileron for stable scale like hovering and flying.

Prior to enabling self-levelling to 'cs+inverted' or 'alway-on', ensure you vibration levels are at least 2 or below.

georgi UK
08-29-2011, 05:54 AM
=] hi Rob, yes I agree!!

maybe = for normal mode reduce the Tx pitch curve end points to give less overall pitch

is a better way to put it!

nycheli
08-30-2011, 11:55 AM
Yes, pitch curve adjustment necessary...
And don't mess around with the cyclic stick at all while your heli is spinning on the ground. The SK does not like that and it could be the reason behind the tilt you saw on lift off.. Just keep the stick at center and get the heli up fairly fastby adding collective.
PS...I learned the hard way with a Walkera 450, never to spool up in the house...even for a test. Trust me, not good!:thumbdown:

Luvmyhelis
08-30-2011, 01:31 PM
PS...I learned the hard way with a Walkera 450, never to spool up in the house...even for a test. Trust me, not good!:thumbdown:

Omg! :wow2:And here I have spooled up my 450s over the years and hover hopped them dozens of times inside!

Not to mention rotating test stand pulls. Like the one I am about to do for my vibe test.
Yes, I know I am crazy.

The rules will obviously change for me though when getting up into larger helis such as a 600. With my luck I would briefly have a perfect real life picture of a 600 imbedded in my flatscreen instead of the Phoenix version. :DOH

georgi UK
08-30-2011, 01:39 PM
=] :rotf:rotf:rotf don't even think about a 600 indoors with blades on!!

fusionsx00
08-30-2011, 07:01 PM
If I ever tried that my girlfreind would kill me if I was still alive.

I had hell convincing her the test flights were were safe with no blades.

Even a 255 size is deadly, I was in the emergency room last year when the blade grip ejected
on my gaui 255(rigid head, no spindle, running new rev, larger bolt in grip)
it sliced my forearm bad, 12 staples and 6 stitches later, I know helis are dangerous

kennethw
08-31-2011, 07:50 AM
I've been hit with my 450 while 'testing' in my living room; have permanent scars to show for it. But have also spooled up my 600 to running speed too, no take-off though.

Back to Snowball's question ... has it been resolved? I used to have the same problem with my 5-blade 450, from no lift it would shoot 15ft into the air. Someone advised me to tighten up all the blade grips to the hub and also tighten the blades to the grip, and the popping disappeared. I guess the slight flex (i.e. SLOP) in the mechanics was amplified when it was negative pitch, but when it reached the tipping point, the blades suddenly went positive by the amont of slop.