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I am setting up a twin engined-model and want to be able to command the engines separately at certain times. Specifically, I always want the engines to respond only to the throttle stick (never any knobs or other items), and I want the left engine to operate alone if the C switch is in the up position with the right engine at idle; the left and right engines operating together in the C center position, and the right engine to operate alone in the C down position, with the left engine at idle. Can I do this?
Absolutely! Like most things with the 9Z, there are many ways to tackle this task. We've given you 3 options here. There are many more.
I. "I have a spare channel on my receiver (1-8), or am using a 7 channel receiver".
A. The easiest approach is to simply put your engines on ch 3 and 7, but in function assign them to NUL. Assign channel 8 to throttle stick and plug nothing into channel 8. Now do 2 mixes, one from channel 8 to channel 3, active on your desired switch in the up and center positions. The other from channel 8 to channel 7, active on your desired switch in the center and down positions. That's it!
B. If you do not need all of the extensive preset programming in the radio for acro mode, you can simply select a helicopter mode, then plug the second engine servo into channel 6, the collective pitch channel. Now throttle hold will put the channel 3 engine to idle, and an idle up can be used to upt the collective pitch channel to idle.
II. "I do not have a free spare channel (1-8) on my receiver."
A. If you do not need all of the extensive preset programming in the radio for acro mode, you can simply select a helicopter mode, then plug the second engine servo into channel 6, the collective pitch channel. Now throttle hold will put the channel 3 engine to idle, and an idle up can be used to upt the collective pitch channel to idle.
B. The easiest approach we can offer you to do this utilizes 5 of your seven available pmixes.
left engine throttle servo plugged into channel 3
right engine throttle servo plugged into channel 7
- Create a pmix mixing thr to 7, 100%, switch c positions center and down:
| ___ | press 2 advanced menu keys |
| ___ | Page up or down to an open pmix |
| ___ | Press + to activate mix |
| ___ | Arrow over |
| ___ | Press + until first box says throttle |
| ___ | Arrow over |
| ___ | Press + until second box says ch 7 |
| ___ | Arrow over |
| ___ | Pull throttle down and press + key until right # says 100% |
| ___ | Push throttle up and then press + key until # says 100% |
| ___ | Arrow over leave link OFF |
| ___ | Arrow over and turn trim on (press + key) |
| ___ | Arrow over leave offset 50% |
| ___ | Arrow over to switch assignment |
| ___ | Press + until says SW-C |
| ___ | Arrow over |
| ___ | Press + key until says CNTR/DWN |
- Left throttle operates properly on the throttle stick already with no changes needed, so that is the up switch position for the channel 3 servo. However, the channel 7 servo needs to be brought to idle, or kill, or however you want it set up. We'll assume you want it to idle. To do so, offset mix channel 7:
Select a blank pmix, make it active, and select the first choice as OFS and second as ch7. Make the percent 50% (you may need to adjust this to match your engine and your desired result), link off, switch C up.
- Now, we need to operate the channel 7 throttle but not the channel 3 throttle when we move the throttle stick while in the down position. To do so, we do a pmix of throttle to throttle, -100% each direction, link off, trim off, offset 50%, switch C down. Now channel 7 operates, but channel 3 returns to neutral, not idle position. Again, like we did in part 2, do an offset mix to solve this problem. Select an available pmix, make it active, OFS to THR, 50% (adjust as needed), link off, switch C down.
- Lastly, we need to turn off the channel 7 knob to avoid its position affecting your right engine, so pmix channel 7 to channel 7 -100% each direction, no link, 0 offset, no trim, and leave the switch setting as NULL.
III. "I want to do this using conditions because I want to practice with conditions and I want to do other things the same time I switch my engine set ups."
This is an EXCELLENT example of a time when conditions and other features specific to the 9Z can be utilized to make an otherwise difficult task easier. Plug in your left throttle servo to channel 3 and your right throttle servo to channel 7, and check servo direction, etc.
- First of all, lets turn off the base controls for channel 7 so that we don't have a problem with the slider normally assigned to this servo causing setting problems. Set Au 1 to Null.
| ___ | From the home screen Press P for Model Menu |
| ___ | Press B then K for Function |
| ___ | Press K to select AU1 (channel 7) |
| ___ | Press P for Control |
| ___ | Press M for next twice |
| ___ | Press E for Null. |
Now channel 7 servo is not operated on its own anywhere; however, it is still at center, which is obviously not what we want for this situation, so we need to do an offset mix to move this servo down to throttle's idle (or kill if that is where you prefer it). To do so, select a blank pmix, make it active, set the slave to Aux 1, the type to offset, and start the offset % at 100%, then adjust as needed to match your installation. NO SWITCH ASSIGNMENT for this one, we'll take care of that with conditions. (For detailed instructions on how to set up a pmix, see part 2 below.)
- Now, the first switch position is already ready! The left engine operates by itself on the throttle stick. Let's get the second set up working now.
Follow our instructions on how to set up a condition which is named SW C 0 (for switch c zero position) or whatever name you are comfortable with.
| ___ | Now, with switch C in the center (0) position, set up a pmix from channel 3 to channel 7. |
| ___ | From home, press O for condition menu |
| ___ | Press B then I for pmix |
| ___ | Select a pmix which is not in use (for example, press F for pmix #1) |
| ___ | press A then F to make it active |
| ___ | Press B then G to make the master throttle |
| ___ | Press C then K to make the slave channel 7 (Au 1) |
| ___ | Press D then E to make it a linear mix |
| ___ | Press R then F to make the trims follow (so when you trim the one engine the other engine responds as well) |
| ___ | Press O for the next screen |
| ___ | Leave the offset at 0% |
| ___ | Press c then M to make the lower half of the throttle respond at 100% |
| ___ | Press D then M to make the upper half of the throttle respond at 100% |
(You can now set up anything else you also want to happen when you are in this condition....gear positioning, other mixes, etc. REMEMBER you MUST have the switch in the position to the condition you desire to adjust.)
- OK, time for the last switch position. Now, first, create a third condition, copying condition SW C 0, and name it SW C 2 (or whatever you feel most comfortable with) and assign it to Switch C position 2 ONLY.
WITH the switch in the position 2 (down) position, go to the PMIX screen. Notice that the mix you created in SW C 0 is still here and still active. Good! We'll need it.
Select a different blank pmix, active, throttle to throttle, linear, trim active, pull the throttle all the way back and press F for set to make a 99% offset, travel -100% each direction, NO SWITCH ASSIGNMENT.
Again, remember, you can now set up anything else you want in this condition to occur when you go to switch position C. Need opposite rudder mixed in to compensate for the yaw? create an offset mix to counter it. want to drop bombs at this time or anything else? now is the time to set up these additional features and enjoy all the power in your 9Z.
THAT'S IT! Go have fun with your twin!
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