D/R Expo is on the Adjust List, just under model select. Clicking on this takes you to the D/R Rxpo setup page, where the middle column is the Rates i.e. the servo travel percentage, and the right hand column is the Expo, which is set to INH (inhibit) by default.
Clicking on one of the INH values and then scrolling will change this to a percentage value; the higher the more damping around the centre of the stick.
Dual rates allows you to set the travel of each control individually, and there is a switch for each as well to enable you to selectively change control travel e.g. setting elevator to "high" while leaving aileron and rudder on "low".
Clicking on a percentage in the first column will allow you to adjust the Rates, or servo travel, individually for each control. The actual amount will depend of how much response you require or how sensitive you plane is. It's worth researching this before your first flight, as super-sensitive controls (aileron especially and also elevator) can be disastrous...
Searching for a solution to the Canadair's pathetic rudder, I happened across some forums discussing differential thrust as a solution to replace rudders, with posts indicating that this thrust solution in fact outperformed conventional rudders.
The idea is that, instead of having two motors always producing the same thrust, when you turn you programme your radio so that the "inside motor" reduces power which assists with the turn. This is particularly desirable in the case of water planes where the plane rudder alone is usually insufficient.
This immediately piqued my interest as a potential software solution to the hardware issues I was facing. If successfully implemented would also allow the rather prone rudder to be removed to the parts box.
There was a minor glitch, however, in the case on the DX6i (and perhaps DX7 as well), as I will explain. The full solution requires three mixes to be used, one to allocate a new channel (usually auxiliary/flap channel) as a second throttle channel, and then two additional mixes which link the two throttle channels to the rudder, thereby allowing the appropriate engine output to be reduced to effect turning (turning right reduces right engine power and vice versa). The issue is that the DX6i has only two mixes available.
Fortunately I came across a forum, including a post by constantmotion on this specific issue, offering a novel solution working within the limits of the DX6i as quoted below: Mix 1: Thro -> Flap Rate D -100% U -100%
Mix 2: Rudd -> Flap Rate D +30% U +30%
"If you go into the Monitor mode you can see how the mixes affect the channel outputs. The left motor ESC goes into the throttle channel, and the right motor ESC goes into the Flap/Aux channel. This is important; if you plug the ESC's in reverse your differential throttle will be backwards. The first mix makes the flap channel parallel the throttle channel for throttle control, and the second mix causes the flap channel to vary depending on rudder position. Changing the rate on mix #2 will affect how much differential throttle you get while turning."
I've tried this on the Canadair and can happily confirm that it works. The only thing I would add, as I discovered, is that the ESC from which the red wire has been disconnected (as apparently you must with multi-engined aircraft) must be connected to the auxiliary channel, while the full lead is connected to the throttle channel.
I happened to have it the other way around and ended up with one lifeless ESC bleeping plaintively until I figured out what was the problem. As my motors were then swapped, I fixed the issue by making the percentages in Mix 2 negative.
The difference between constantmotion's solution and the 3-mix version is that only one motor gets variable speed, increasing or decreasing as per the percentage set in Mix 2. The only time this would not function is if you were turning away from the aux motor side on full throttle, in which case the aux motor would, of course, not be able to speed up.
I have conducted a bench test of this system and it shows potential, but am hoping to do a water trial soon to confirm just how effective it is. Hopefully it will work sufficiently well to allow me to dump the rather underwhelming original rudder...
...tail-heavy no more I took the Phoenix out for a fly this afternoon, not having flown it for a while, and took the opportunity to try the flap mix which was something I'd overlooked when I first got the transmitter. I'd set the Phoenix up for flaps when I'd first got it, but have never particularly liked flying with flaps as it makes the Phoenix fly tail-heavy, dampening what are generally immaculate flying manners.
This is because the wings are in a high-lift configuration but the tail is not, causing it to dip at low speeds associated with flaps. The other day, flipping through the menu's when setting up the Stinger, I came across the flap mix menu and suddenly it made sense.
The mix is very simple, allowing you to dial in a dose of elevator with the flaps. Now the trick is, to cure tail-heaviness as in the case of the Phoenix, you don't want positive elevator, as this would just push the tail down more and increase the angle of incidence of the wings.
What resolves the issue remarkable well is negative elevator, effectively working as a flap for the tail. On the Phoenix I set negative elevator at 20 for a flap setting of 10, which I tried out this afternoon and which works brilliantly well. Highly recommended on the Phoenix...
...the expo setup's all good Last night I set the expo rate on the controls - easy now I'm got used to finding my way round the menus on my DX6i. I set the rate at plus thirty percent which seemed to work well, although I was only flying the Walrus on the desk. So the controls now look promising, easier to control small movements but still leaving good travel for big manoeuvres, which sounds like a good setup. Now just hoping for another flyable window - very blowy again this morning unfortunately...
...so many toys In the aftermath of the aileron chatter incident, the wing camera and Walrus have taken a bit of a back seat - no point in having a brace of aircraft and nothing to fly them with! Anyhow, with the new Spektrum DX6i transmitter nowin hand, so to speak, the next thing to do is get the Walrus finished. It's a pretty easy build - just glue on the vertical and horizontal stabilisers and screw on the wings. The servos are already installed with only the setting of the servos requiring attention.
I am still a little unsure of the best approach for this, although I am going to leave the control rods off until I have powered up the Walrus so that I know where the neutral positions are going to be. That's the theory anyway. The canopy of the Walrus I find a curios configuration as it created a dead-space with the canopy itself attached to a "frame" creating a miniature blacked-out cockpit. As this space would comfortably accommodate the wing camera I've chosen to screw the canopy on, allowing later access I might also swap these for magnets if I end up using this space regularly.
I've tried out the wing camera and found the video quality to be pretty impressive for such a tiny device. I have also managed to correct the settings, so that videos won't be date stamped 2091. Curiously though, you have to connect the device to a television to access the setting menus, which seems a bit retro for such an advanced piece of kit. Anyway, the weather for tomorrow is forecast to be still so I hope to take the Phoenix, complete with wing cam, for a bit of a fly...
...along with the Dx6i I have finally completed programming of the my Spektrum Dx6i transmitter and am happy to report that all systems on the Phoenix are working well. I am going to try running the flaps on the Phoenix "back-to-front", that is having them slightly reflexed for powered flight and then set them neutral for gliding flight and landing. This should help to reduce the tendency to climb sharplyunder power. I can also alter the degree of flap reflex and change elevator trim if required. This should be interesting to try out... I've also changed the power setting of the transmitter from EU to US, which apparently gives about twice the range, equating to an absolute range of about 500m, in my experience. That should be sufficient to should resolve any signal-loss issue, although that will remain to be confirmed in practice...
...and sanity maintained Unfortunately trying the radio the next day and the chatter was back again - unfortunately my quick fix had limited remedial abilities. It was too much of a risk as the random movement could put the Phoenix absolutely anywhere and I didn't feel like that sort of a risk! After having scratched my head and swapped everything in sight I finally bit the bullet and decided I needed to get another transmitter. Not that I really wanted one, in fact I didn't want to have to get another, but as far as I could see there wasn't any other option. Everything pointed to the aileron gimble on my unit as the culprit. Thinking back, the ailerons on the Phoenix had actually chattered from the very first time I powered it up. Of course I didn't know then that it was actually the radio and not my crappy assembly effort. So, after doing a little research I bought a programmable Spektrum DX6i 6-channel unit, the same make as my DX5e so as to be compatible with the receivers I already have. Now what I have found very interesting is that the programming abilities address two of the main issues I've experienced.
Firstly, it has two modes, flying and landing, allowing you to customise settings (flaps, elevator) to suit each regime and switch between them. In my case I want to use it for powered flight (reflex the flaps and a maybe a touch of negative elevator) and for gliding with everything neutral. Secondly it has programmable travel, exactly what I want to make the Phoenix flaps manageable instead the source of mirth they are at the moment. Anyway I have bound the radio and, after wondering why I was getting weird mixing between elevator and ailerons, switched from helicopter to aircraft mode. I still need to do the servo-reversing for rudder, program mode settings and flaps. So the manual is getting studied well and truly as i don't want to fail this exam...
