DLG Launch and Zoom mode

Here’s another setup guide from a forum request, user had it working but not the way he was using it in OpenTX:

For my DLGs currently I have 5 flight modes. Using a spring loaded three position switch, I pull the switch to activate launch mode, release it to let it spring to middle position for zoom mode. After the zoom on a launch, I flip that switch to the 3rd position to disable zoom mode and allow another 3 position switch to activate Speed, Thermal and Cruise modes. Launch and Zoom are higher on the priority list so when I pull the switch again it overrides the normal flight modes until I manually push the switch to the 3rd position. 

I do this because flaps need to be disabled for Launch and Zoom modes for quick turnaround tasks. 

OpenTX accomplishes the same thing with a 2 position switch. Spring loaded held for launch mode, release for zoom mode, then moving the elevator stick past a certain point deactivates zoom mode and allows another switch to change the normal flight modes

This had me baffled for at least two mugs of coffee, but during third mug I got it, so here it is.


  • Model is started in normal flight modes depending on the 3-position switch. (Cruise, Thermal or Speed)
  • When momentary switch is activated and held in activated position we are in Launch mode
  • When momentary switch is released we are in Zoom mode
  • When elevator stick is moved to a pre-defined position from middle we are in any flight mode the three position flight-mode switch is in


Needed setup:

  • 5 flight modes, Cruise, Thermal, Speed, Zoom and Launch
  • 3-position switch for basic flight modes Cruise, Thermal and Speed
  • Momentary switch for Launch mode
  • Elevator stick’s switch positions defined to user’s liking (and direction)
  • 3 logical switches

How to set things up

Let’s start by setting the elevator stick as a switch. This setup shows the deactivation of Zoom mode when elevator stick is pushed all the way up.


Next let’s do the flight modes. Note the order of flight modes, Zoom has to be above normal flight modes and Launch needs to be above Zoom. Set the activation switches as in picture below. No need to care about the fact that Logical Switch L3 is not done yet.


Now, the necessary stuff is done, let’s dive into Logical Switches and make things fuzzy!

Logical Switches

First flight mode Logical Switch, control 1 is “Momentary launch switch in OFF-position” and control 2 is “Elevator stick in the middle”. This means in practice “both controls needs to be active in normal flying mode and level flight”, set condition as “AND”.


Second Logical Switch is a simple “L1 AND L3”, don’t worry about L3 not been done yet.


Third Logical Switch is “Momentary Launch-switch in ON-position AND L2”. In the picture below momentary launch-switch is off.


And you’re ready!

How it works

Here’s an explanation on how the setup works, keep an eye on the upper screen for flight mode information.

We have started the model, L1 is active since elevator stick is not in “disable zoom”-position and launch-switch is not in launch-position. This means we are in the flight mode the 3-position flight mode switch defines, in this case in cruise mode.


Now, we activate the momentary launch-switch. Since L3 is “Momentary switch active OR L2 active” and we have activated the momentary launch switch we are in launch mode as seen on upper part of screen. Even if L3 controls the Zoom flight mode we are in Launch mode since we set the Launch mode higher up than Zoom in flight mode setup, remember?


After releasing the momentary launch switch we are no longer in launch mode, but since we have not moved elevator stick yet L3 is still active. And since L3 controls Zoom mode which is higher than the normal flight modes we are in Zoom mode, seen on the upper part of screen.


Finally, after moving elevator stick beyond the activation point we are disabling L3 and therefor return to flight mode controlled by the 3-position switch assigned in Flight Mode menu, in this case Cruise:


After this chain of events activating the switch made by elevator has no other impact than activating and deactivating L1. And since momentary launch switch is not in launch position this has no impact, we are either in Cruise, Thermal or Speed modes depending on the position of the flight mode switch.

Video – In practice

Here’s the function in practice demonstrating flight modes and reaction speed, keep your eye on the flight mode display on top fo screen:

There you have it, fizzy and momentary to latching functions for DLG!

8 thoughts on “DLG Launch and Zoom mode

  1. I implemented automatic zoom after launch phase using a sequencer (it enables zoom unconditionally for 2-3 seconds after releasing launch) but I missed the possibility of interrupting zoom just touching any control like elevator or aileron. I couldn't imagine this can be done without using LUA programming. Thanks for your contribution!! It's brilliant.

    By the way, I use DS accelerometer for triggering launch mode rather than temporary switch.


    1. Do you still use the DS accelerometer for launch phase? Can you tell me how you set this up to work? What movement triggers launch mode and what movement or action transitions to zoom mode after? Thanks!

  2. Really appreciate you having this posted for all to share, Helped me a great deal. Thanks

  3. Awesome and works :-) but I cannot work out how it works even though you have explained it! How does the radio do the logic if L2 is dependant on the result of L3 and L3 is dependant on the result of L2? It's circular logic??

    1. L2 and L3 are needed for the required AND/OR logic, so yes, sort of circular logic.

      Might be easier with latest firmware, have not checked :)

      1. Thanks for the quick reply. Im a programmer and understand logic gates, but I can't understand how the Jeti can calculate the values? Any program I have written would fail – the result can't be part of the calculation. Im totally baffled.

        1. Remember there is an "invisible" logic in the loop. The order of the Flight Modes, where Zoom and Launch have higher priorities than the normal flight modes, creates another layer of logic gates that is not visible in this howto ;-) I I had time, I could have played with an logic gate simulator to create a visible view of the final result, but I will leave this to someone else ;-)

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