GrantL
Senior Heliman
Location: Springfield, MA
My Posts This: Topic Forum | Regarding the SK360You might want to take note of this with regards to large scale helis... this was posted by Skookum on another newsgroup.. This happened to me and rolled my Long Ranger into a ball....
Hi All,
My apologies for not putting instructions for the piro/spoolup bank idea on the website. To recap the IRCHA discussion:
I believe that what's happening during the final few seconds of autos is similar to the problem that some large scale helis have during spoolup. In both cases, at low head speed the unit can over-control the heli. This occurs because it doesn't see a very strong response to swash motion, so it keeps moving the swash more and more.
During a slow spool up, where the pilot's commands from the receiver might not be zero, or the heli is wobbling a lot, that can result in tipping.
During the last few seconds of an auto, I think three more effects happen: First, as the unit uses more extreme cyclic-swash motion, that creates a lot of drag on the blades, so they slow down faster, so it needs to use more control, etc - so it tips over, even while spooling down. Second, a flybarless gyro will try to give the pilot equally sensitive control at all times, even though the controls should be moved gently during an auto so as not to bleed rotor energy. A flybar'd heli will naturally limit the pilot because its sensitivity is lower at lower rotor rpm, but the flybar'd system invites overcontrol. Finally, the disk is quieter flybarless and (I find) that makes it harder to judge rpm (so be conservative and land before you can see the blades).
For the SK360, my proposed solution was to just have two banks, one for normal flight and one for spool up / autos. So if you haven't already, follow the instructions in section 13 of the manual to set up a second bank.
Then make that second bank a copy of your normal bank, except for three changes:
1) Lower control rates
2) Lower Hiller Gain (about 1/2 to 2/3 normal, set either directly or via the gain input channel)
3) Higher hiller decay (at least 150%)
You can then spool up or auto with the system heavily damped down, so it will not tempt the pilot to overcontrol (1), be less likely to overcontrol itself (2), and forget its frustrations with lack of response faster (item 3).
Grant |
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