RAK402
Key Veteran
Location: Alhambra, CA
My Posts This: Topic Forum | Nick,
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"RAK402, how can yours roll flat with the stock phasing and others' dont?
Did you add swash expo to change the head interaction?
I don't know what to think at this point....
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A:
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KBDD-Compass Field Rep.
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A bit unkind sir. They don't pay me to do this, although I do get some discounts-it is not worth my credibility.
I have been flying R/C helicopters for 32 years now, and still own about 30 different machines, including three Compass products, three Raptors (if you count a Mini-Titan as a Raptor), four Align products, as wall as a motley assortment of Hirobo, Kavan, American R/C, Venom, Eflite, Walkera, RC-Tek, etc. (you get the picture).
Let me caveate that by stating that I do not purport to know everything about these machines or flying them--although I am pretty d@mn old (not to mention, quite ugly), there is always something new to learn (probably too much, in my case). I mention how long I have been at this not to suggest that I know more than you (or anyone else for that matter), but just so you won't think I am some young Bozo who does not know what is going on (I may just be an old Bozo, I leave that to your judgement, sir).
"Another interesting bit of info is that 0deg phasing isn't necessarily correct either, although it's better than what they've done."
I have been playing with varying the phasing on my machines for a while now. I noticed, when I first got my Knight Pro, that the nose would pop up as it rolled through inverted. My Knight 3D and my Raptor .50 did this as well (initially I chalked this up to pilot error). The head phasing/timing was set to 0 degrees. I noticed that my old, first generation TREX 600E did not do this. It rolled flat. I then noticed that TREX 600's that my friends let me fly, did not roll flat (I did notice that I was the only one, doing slow rolls, so no one else noticed what I noticed).
I kept looking and examining what was different on my 600E vs. other TREX 600's (both E's and N's) and my other machines (of course the bell/hiller mixing scheme, head design, etc. is quite a bit different on my various machines). As it turned out, the swashplate timing was not at 0 degrees on my 600E. The swashplate, as viewed from the top, was a few degrees behind Zero. This particular model has a plastic washout base and arms, and is the only one I have ever seen like this (and I have examined a lot of them since). Thinking this might be a clue, I tweaked the timing on both of the Knights to reflect what I saw on the 600 and it cured the roll issue.
My TREX 450's also had an issue with the nose popping up as they passed through inverted in a roll. I could fly through it by pulling back on the cyclic at the appropriate time (I do believe in flying through the manuevers-not just banging the stick over and hoping for the best), but it was somewhat annoying. The swash timing is fixed on these machines, so a timing adjustment was not an option.
I had been reading about the "Swash Expo" feature in the JR radios, but had never used it. As a test, I invoked the feature on the radio, re-set the Pitch % in the Swash Menu, and flew the little TREX's. The rolls were much flatter than before. On the bench, holding full aileron and raising and lowering the swashplate, as one would through a roll, demonstrated the grossly decreased swashplate interaction with the "Expo" feature invoked as opposed to when it was not (the swashplate did an interesting sort of "hula" without the feature invoked). Testing this feature on the larger machines showed an even more profound reduction in swashplate interactions-making general flight characteristics better, handling easier, etc.
Since then, I have started using the "Swash Expo" feature on all of my CCPM helicopters (obviously, this is not an option on the Raptor). The rolls are flatter still.
I was pleased when I saw the swash timing on the Atom from the factory, as it was about exactly where I would have put it (although, in retorspect, I might have made it a degree or two less in offset).
"The issue comes to a head when you do the long slow rolls that RAK402 references. The phasing setting that Compass decided to build into the head is really going to help your long slow rolls when doing them to the right (I believe that's the direction off the top of my head, it may be left), since it is inputting the roll command just a little late it is automatically giving you a little up elevator which is bringing the nose down during the inverted section helping to keep it flat and moving forward."
This I have to plead guilty to. When I got my first Heliboy, in 1978 (and I wish now that I had kept it), I was taught by the then local experts, always to roll into the receding blade, so I have always done right hand rolls. I have no contest ambitions (that was thoroughly beaten out of me in the 1970's and 1980's) and have the good sense to know that I will never be an Alan Szabo or Curtis Youngblood), so I never bothered to get used to rolling to the left.
I did notice initially, when flipping, the cyclic felt strange and the tail was skewed over to the left (as though I applied left rudder and aileron in the flip). I went through and reamed the ball links (mine was a pre-production machine and the links were very tight-especially the special ones from the washout control arms to the swashplate and the links from the servo arms to the swashplate). This cured the tendency to roll while flipping.
I then increased the gyro gain in the radio (that straightened the tail out).
I am not a stick-banger. Far from it, I was taught (back in ancient times) that flying smoothly and gracefully was everything. While I admire their skills, I do not have the reflexes of the young guys, so I have to tweak and tune the helicopters as much as I can, to get the to fly as easily as I can, in order to be able to do what I want with them.
By the way, the blades on mine are the yellow/red-yellow/blue MAH blades, if that means anything.
I would imagine, although I do not have any inside information, that if enough want the phazing changed, they (Compass) will change it).
Sorry for the long, spectacularly boring post.
KBDD-Field Rep./Compass Support Team |
