TQ6+ and the reverse detent

Black Square

I thought that might be the case. That was the next thing I was about to write to you after your chart. The mystery is still why your hardware input acts the way it does, since that number should only be a limit, and not changing the scaling of values outside the reverse range. I planned on changing that configuration value to -1.0 for all my aircraft, since it results in much more realistic fuel control in the reverse range. I wouldn't want to mess up the throttle axis for many of my users, but I also don't really understand why yours is behaving the way that it is.

brettsan

@Jiblet
If I want to try your fix again, which engine.cfg do I need to change, all of them?

Jiblet

@brettsan - Yep, all of them.
Or at least all the ones you want to fly - each engines.cft is for a different variant. So one for the cargomaster, one for the amphib, etc.

@Black-Square - Yeah I'm not sure what VFHub is actually doing under the hood. Annoyingly its a blackbox that appears to have no documentation for that. Which for a £700/$800 unit is ... a choice.

Can I ask why your planes have that -0.15 value in the first place? It seems like a very deliberate value from what you've said there.

Black Square

@Jiblet said in TQ6+ and the reverse detent:

Can I ask why your planes have that -0.15 value in the first place? It seems like a very deliberate value from what you've said there.

Not sure, to be honest. I searched for this parameter in all of the default aircraft, and they all either have -0.15 or -0.25. In my experience, the reverse system in MSFS is one of the most antiquated, with a mixture of the new propeller simulation, and code from at least 25 years ago.

Unfortunately, it does make a substantial difference to the performance of my aircraft, so I would like to roll out this change to the entire fleet. I would hate to leave you guys editing configuration files as a solution, though.

Do you think the issue here is that Virtual Fly assumed aircraft only use this -15% number, and somehow scaled their reverse input to that?

brettsan

@Black-Square

I know another person in Virtual Fly and he used to more the "face" of the company. I will send an email to him and explain what we are trying to accomplish as best I can and see if he replies. As I said above, I was shocked by this one support experience as it was certainly not what I was used to. The only issue, it has been years since I spoke with him.

I will get back to you with my results.

Jiblet

Thanks @Black-Square I've jsut done some 6am testing on a bunch of non-Black-Square aircraft and found some "interesting" results. And by "interesting I mean "annoying".

Basically VFHub seems to just send raw values of between +100 at full forward throttle, to -25 at full reverse, with 0 at idle. And that's that. No logic, no scaling, no looking at the aircraft type or its engine values and doing anything clever.

I think they may have done something like you mentioned - looked at the values for default planes and said "yeah that'll work".

This is "ok" with a lot of aircraft - eg most of yours, the Avanti Piagio and the King Air 350, which all have it set to -15. Even then, its not perfect. It leaves the hardware throttle with about 40% of it's rearward travel left to go, because it's scaled form 0 to -25, so you hit -15 at 60% travel.

Then for some planes, like your Caravan Pro, the Kodiak, and the Twin Otter where they all have max reverse values of over -25 (if over is the right word), eg the Twotter is -34, the Kodiak -65. For those planes I just get a partial reverse because I'm maxing out at -25.

Annoying. I'll try to write a useful support ticket for Virtual Fly but I don't expect a useful answer. Perhaps the real solution would be to learn Spad.next but that UI gives me the heebyjeebies.

Thanks for all your help with this. And everyone else who had some input!

brettsan

@Jiblet

Thanks for your earlier reply about changing the engine.cfg... going to give that a go...

I tried support previously but didn't get anyway... likely because I probably didn't explain the issue well enough. I have since sent another email to someone else in the company that I worked with previously to see if he would be willing to help. His email didn't bounce, so I hope that means he still works with the company.

"Yes, I saw your email above.... but thought I would send anyway to confirm... can't hurt right?"

Jiblet

This post is deleted!

Jiblet

@brettsan I'd suggest going for -0.25 on the min_throttle_limit

I've not actually tested that on the Caravan yet, but it should mean that the reverse section of your TQ6+ behaves perfectly (full travel with no deadzone at the end). And hey it gets you a tiny bit closer to the -1.0 Nick wants to get to

Jiblet

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.