I heard back from VirtualFly:
"We have spoken with our software development team, and they have confirmed that this is one of the points they have noted for improvement in VFHub. However, they currently have other priorities, so work on this will not begin until after the summer.
We really appreciate the level of detail and analysis you have provided, as it helps us identify and prioritize these kinds of improvements."
So I guess we'll see.
For the record and to close this out at least for now, here's what I sent them:
Hardware: TQ6+
Serial: 310540
Software: VFHub (v1.3.9)
Sim: MSFS 2024
Description of Issue: I am experiencing a significant scaling issue with the throttle reverse axis on the TQ6+ when using VFHub in Microsoft Flight Simulator.
It appears that VFHub sends a fixed throttle variable range of +100 (Full Forward) to -25 (Full Reverse). While this worked for older default aircraft, many modern high-fidelity turboprops (specifically from Black Square, SWS, and Aerosoft) use different min_throttle_limit values in their engines.cfg files.
The Problem:
Incomplete Reverse Range: For aircraft like the Black Square Caravan, Kodiak 100, or Twin Otter, the min_throttle_limit is set between -0.65 and -1.0. Because VFHub caps the output at -25, I can only access about 25% to 50% of the actual reverse thrust power available, depending on the aircraft.
Dead Zones: For aircraft using the -0.15 limit, the hardware lever reaches the sim's maximum reverse value at only 60% of its physical travel past the detent, leaving a large dead zone at the back of the hardware's range.
Evidence: Through testing with the Black Square developers, we confirmed that manually changing an aircraft's min_throttle_limit from -1.0 to -0.25 fixes the physical axis behavior for the Black Square Caravan, but ruins the aircraft's flight model and fuel flow realism. Indeed, setting that value for any aircraft is what you have to do to make the throttle line up.
The Black Square developer has indicated he intends to move the entire fleet to a -1.0 limit for realism (see https://community.justflight.com/post/49046), which will effectively break the reverse functionality for all TQ6+ users unless VFHub is updated.
Steps to reproduce: If you have the Black Square Caravan, it's very noticeable in that. Alternatively the DHC6 Twin Otter included in MSFS 2024 also displays similar behaviour.
Run MSFS 2024 and VFHub, with the TQ6+ connected
Load in to the game on any runway in the DHC6 Twin Otter or Black Square Caravan - these aircraft show it best but it does affect most turboprops
Look at the throttles in game and bring your physical TQ6+ throttles back into reverse, all the way to the bottom of the travel
Look at the throttle(s) in game and you'll see that they are not at the full reverse. In fact you can grab them with the mouse and pull them further back.
You may also want to use a tool to show the changing value of (A:GENERAL ENG THROTTLE LEVER POSITION:1, percent). That will let you see the data rather than just eyeballing the throttles in game.
Requested Solution: Could VFHub be updated to allow for dynamic scaling of the reverse axis? Ideally:
VFHub should detect or allow a setting to map the full physical travel of the TQ6+ reverse range (past the detent) to the full available range defined by the aircraft's min_throttle_limit.
Alternatively, perhaps provide a user-configurable "Scale" setting for the reverse portion of the axis within VFHub.
Or perhaps there's a better way that your team could come up with, I'm not fussy about the solution, I'd just like it fixed
I realise that you don't support third party planes directly, but that's not really the issue here. Any plane using a value other than -0.25 for the min_throttle_limit in engines.cfg will have the issues I described above, and I'm yet to find a default plane that uses -0.25 - at best they use -0.15, so this issue is widespread. As a user of VirtualFly hardware, I would love to see the software black box opened up or updated to support these modern aircraft standards.
