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Apr 20, 2018, 12:01 PM
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Combing Flaps with Flight Modes on Spektrum Transmitter


This guide will go through the process of combining flaps with flight modes. I can confirm that this works with the new (black) Dx6 and Dx7 and I assume it can work with any of the new "black" transmitters that have Spektrum's newer UI. However, I know that this trick is NOT POSSIBLE using a Spektrum Dx6e and I suspect it might not be possible on the Dx8e, but I haven't confirmed this yet.

So, what's the point of linking flaps with flight modes? Good question.
Have you ever had a plane where you deploy the flaps and the plane dives or climbs dramatically? Have you ever deployed flaps (or flaperons) and noticed your plane rolls a bit left or right, but flies fine with flaps up? Having flight modes linked to flaps can help you take care of these issues in-flight in real time without the need to land and go through your Tx settings.

How does it work?
By combining the FLAPS and FLIGHT MODE (which I will abbreviate as FM) onto a single switch, you can set independent trims for each flight mode and flap setting. This means that each flap condition (Flaps Up/Half Flaps/Full Down) will have independent trim from the other flap conditions.

How do we set this up?
I made a video and you can watch it as I go step-by-step through the process. There was no script and I had to hold the phone myself while navigating the menus, so it's not the best, but it will tell you what you need to know.
Setting up flaps with flight modes on Spektrum transmitter (4 min 1 sec)


However, if you'd prefer written instructions - see below.

I'm starting with a clean and brand new model configuration. I can't predict what previous settings/configurations YOU have, so if my steps aren't working for you, I suggest you also start with a brand new model from scratch and see if that works.
  • From the main screen (should show a picture of the airplane and trims) hit the roller button and go to System Settings. Hit YES.
  • From this menu, go to Aircraft Type and move to the WING selection area and choose the type that best fits your model. 90% of my planes are setup using either (1 AIL, 1 FLAP) or (Flaperons) for my jets. For the sake of this tutorial, we are assuming (1 AIL, 1 FLAP).
  • Once you’re done on this screen, hit the BACK button on your transmitter to go back to System Settings and then navigate down to F-MODE SETUP and enter that menu.
  • Go to where it says "Inhibit" and select it using the roller button. Then assign it to whatever switch you want to use for flaps. In my example I will use Switch B, which is a 3 position switch. Once you have done this, hit the BACK button to go back to System Settings.
  • From the System Settings screen, scroll down a few rows to Trim Setup and enter that menu. Here you will see a list. Change Aileron, Elevator and Rudder from COMMON to F-MODE. Don't change anything else. Once complete, hit the BACK button to go back to System Settings.
  • Hit the BACK button again to get back to the main screen (shows the airplane icon with trims).
  • Press down the roller button to bring up the menu and go to FLAP SYSTEM. In the Flaps menu, you will go to where it says INHIBIT and change that to be the same switch you used for Flaps. In this example, I'm using Switch B.
  • After selecting a switch, the Flap Settings should now be on the screen. This is where you tell the flap and elevator servos how much travel they should have for each switch position. FLAP = how much the flap servo moves and ELEV = how much the elevator moves.

What's that you ask? "Why is elevator here in the flaps menu?"
Well, this is useful if your plane climbs or dives when you deploy flaps. You can preemptively correct the pitching motion of the plane with flaps using that ELEV column in this menu. That way, when you deploy flaps the plane won't change pitch.

And I can hear you thinking; "But why do I need Flight Modes if this feature is here?"
Well, here's the issue. This elevator compensation is only available in this menu. That menu is hard to get to while you're flying a plane, especially if it's a maiden flight. You practically have to land the plane every time you want to make an adjustment to the elevator compensation. And sometimes that can be a "pick a number and hope for the best" sort of thing and could take multiple tries.

Having Flaps tied to FM will let you adjust all that in the air in real-time. It will also let you fix any roll effect the flaps might have on the plane, which is something the flap settings can't help with (currently).
  • Alright, so back to the Flap Setting menu:
    Each plane is different, so this is going to be something you'll need to test out on the bench. But for the sake of my example, let's assume the following:

POS 0 = 0% (no flaps)
POS 1 = 50% (half flaps)
POS 2 = 100% (full flaps)

In this example I'm going to leave ELEV alone, but if you're certain that you need some elevator compensation and know about how much, go ahead and put it in here as a starting point. For the sake of this example, I'm assuming no ELEV offset.
  • Go to SPEED and change that to whatever you want. I recommend 3 seconds as it gives the flaps a nice scale deployment speed, but it's all up to you.
  • Once you're done, hit the BACK button twice to get to the Home Screen with the picture of the airplane.
  • That's it for the setup, you're ready to go!

Things to note
  • Remember that each FM/FLAP setting now has independent trim. This is helpful but can also be a problem. Here's a real example of something to watch out for:
    I went to maiden an airplane and when I got it in the air it required a lot of roll trim to level it out. After a moment I got everything trimmed out and the plane flew nice and straight. However, as soon as I deployed flaps the trims went back to neutral for everything because we were in a new Flight Mode and the trim in THAT flight mode hadn't been adjusted yet. So, when I deployed Flaps this caused the plane to revert to its bad rolling tendency until I re-trimmed it again with the flaps deployed.

    This is just something you have to remember when you are "dialing in" the plane with Flaps + Flight Modes. If the plane requires a LOT of trim to fly neutral with flaps up, then be ready to adjust the trim again once you drop the flaps. However - once you do this once, you should be good from then on. Though I recommend trying to mechanically trim your airplane whenever possible - but that's not for this tutorial.

  • The last thing I need to mention is the speed of FM vs Flaps. Remember when we set Flaps to 3 seconds? That makes them look nice and scale and prevents abrupt changes to the flight envelope. That's a good thing. Unfortunately, the Flight Modes don’t get that delay. What does that mean? Basically, if you deploy your flaps, the trim settings for that flight mode take affect immediately, but the flaps themselves deploy over the next 3 seconds. This has never caused my “trouble”, but it’s good to know that the flight mode trims take affect before the flaps have fully deployed.

    Example time:
    I had an EDF with flaperons. When I deployed flaps it would roll a bit to the right. I fixed this using FM trims. When I would come in for landing I would put the plane into the landing pattern (flaps up) and then deploy flaps when I was on final. For a brief moment after deploying flaps, the plane would roll just a bit before the flaps fully extended. This is because the roll trim applied as soon as I hit the switch, but my flaps took 3 seconds to fully extend. Once the flaps were down it was flying fine, but the transition periods in-between the flap deployment might cause the trim to overcorrect the plane for a very brief moment. To the best of my knowledge there’s no way to compensate for this. The only solution I know of would be to reduce the flap deployment time to 0 or 1 second, but then you get abrupt flight envelope changes, which I try to avoid.


That's all I've got for this tutorial. I hope it helps some people out and gives them a bit more agency over how their plane is trimmed with flaps. I use this feature mostly on my EDF Jets using Flaperons, but I find this is also helpful on standard planes using full flaps. If you have any questions, let me know.
Last edited by Suko; Apr 20, 2018 at 12:31 PM.
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