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Propeller pitch reverse and power back

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After being unable to power back the DC-6 (it actually would move forwards) I decided to take a look at the datarefs when applying reverse pitch while breaking and this somewhat strange picture developed:

 

 

NfaK8GUy.gif

 

As you can see immediately after applying reverse the prop pitch (in red) jumps from +12 to -25 only to drop back quickly to 0.

The thrust (green - right axis) follows but has that weird double peak - at first I assumed that it was due to the throttle (yellow) being pushed further back, but it is also present if you do not touch the throttle at all.

 

Shortly after the pitch reaches 0 the reverse thrust diminishes with aircraft speed (blue) and actually provides forwards thrust below 50 knts which explains why you can't power back.

 

Now I don't have experience with a real DC-6 but this really looks weird.

Maybe it's x-plane doing something strange with the datarefs but the speed seems to match the other data or maybe it's a bug in how negative pitch values are handled... 

 

Should I report this to support?

 

I just want to be able to power back  :wub:

 

 

Martin Peters

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Hi there!

 

Thats indeed a strange issue, because I'm able to do powerbacks without any Problems. For me it did even work with just 2 engines running. So i don't think it's an x-plane issue. I set my main prop-RPM Lever to full forward, then throttles to idle, pull back the reverse-handle, an then quickly add power.

 

Hope you get it sorted out! Just don't hit the brakes while you're reversing. :P

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What kind of setup do you use for your throttle? I used buttons to throttle up and down to avoid potential axis problems but maybe those were the cause of the problems...

Will have to check that later...

 

Edit:

 

The input type seems to be the problem here indeed.

 

With an axis as throttle input reversing works as expected - still that strange double peak thrust though, however the pitch stays negative and thus you can de-accelerate and eventually reverse as expected.

 

rDn94YFF.gif

 

One obvious difference is that with buttons as throttle control you need to press "throttle back" to move the levers further back, while you move your joystick axis forward again, which is sort of wrong but I suppose necessary to deal with the hardware limitations.

 

Apparently this confuses the pitch algorithm in that it dials the pitch back to 0 instead of putting it at -13, which reduces breaking power dramatically and makes powering back impossible.

 

I guess if PDMG wants to fix this they need to adjust that logic to account for a button controlled throttle - should I submit a report?

 

Thanks Matthias, for your input - knowing that it worked for you put me on the right track there.

 

 

Martin Peters

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I ran into a similar issue where most of the time, I couldn't engage the reverser lock (even though sometimes the yellow reverse lights would come on), and when I could, when applied reverse thrust, even though the animated controls moved backwards, the plane would accelerate forwards.  I'm using a CH Products quad.  What I found what that if the four throttles where out of sync at all, which is most of the time, with four controls, I would have issues.

 

My solution was to use the CH Control Manager and putting in dead zones and specific range values at the detent so that when the controls are in the detent, they all send out the same value.  Note that if you use the Control Manager, it creates new virtual joysticks so you have to remap your controls to these new joysticks.

 

Cheers,

Phil

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I'm

 


Maybe it's x-plane doing something strange with the datarefs but the speed seems to match the other data or maybe it's a bug in how negative pitch values are handled...

 

I have no idea if the pitch values are valid.  I do know that there are XPlane modelling quirks that didn't fit a large radial prop engine and are modeled outside the XPlane box.

 

I suggest you may save time looking elsewhere for your reverse pitch problem.

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Sorry, didn't see your replies before editing my second post.

As said there the problem is that reverse pitch and power back only work properly when you use a joystick axis to control your throttle.

 

If you use keys or even drag back the levers with the mouse the pitch logic apparently gets confused and sets the pitch to 0 - with very limited breaking power.

 

I suspect the problem is that the algorithm expects the throttle input to move forward again after you've flipped the switch, while with keys and mouse you  move the throttle further back.

 

Martin Peters

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I use 2 Saitek throttle quadrants, 1 prop-RPM lever, 4 throttle levers, and 1 lever for all carb-heaters. For the reverse-handle I've set up the "buttons" in the reverse-zone of the TQ. So I can pull back the trottle levers to idle, move one of the levers into the reverse-zone of the TQ to trigger the reverse-handle, and then add reverse-power by moving the throttles forward. To return to normal prop-pitch, same procedure again. Works like a charm!

 

Never tried by using Buttons only or by pulling the levers with the mouse.

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Another pitfall is failing to put the prop levers full forward, I had an epic time witnessing a single flash on the yellow bulbs, then nothing and the aircraft thrusting forward even though the throttle was in the reverse zone. And wondering why. Now I'm pretty sure that was my mistake!

 

And yes, do not brake in reverse, this would be most awkward  :wink:

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move one of the levers into the reverse-zone of the TQ to trigger the reverse-handle

 

Which button assignment do you use to move the reverse handle?  I assume it is in the engines category where the other reverse commands are, but you know what it does when you assume!   Everything I have tried (and it works with my heavies) only turns on the reverse lights.  I would probably figure it out, but if you can save me some trial and error search time, it would be appreciated.  I'm old and don't have much time.

 

John

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Glad you found it. For all others, it's a key-command that comes with the DC-6:

 

PMDG_DC6/propellers/reverse_lever_toggle

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Let me re-explain that.

I can read. I did use the function. there is no reverse pitch in any sense of keyboard, buttons or internal Virtual cockpit

it only works with a throttle or slider.

 

so....  NON-FUNCTIONAL


quoting ealrier in this post since people cant seem to read back a few lines

 

"

Sorry, didn't see your replies before editing my second post.

As said there the problem is that reverse pitch and power back only work properly when you use a joystick axis to control your throttle.

 

If you use keys or even drag back the levers with the mouse the pitch logic apparently gets confused and sets the pitch to 0 - with very limited breaking power.

 

I suspect the problem is that the algorithm expects the throttle input to move forward again after you've flipped the switch, while with keys and mouse you  move the throttle further back."


It is functional.  Read the post just above yours.

 

John

You read the post above mine, it was a question about the toggle command not about reverse pitch failure

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Let me re-explain that.

I can read. I did use the function. there is no reverse pitch in any sense of keyboard, buttons or internal Virtual cockpit

it only works with a throttle or slider.

 

so....  NON-FUNCTIONAL

 

Saying something doesn't work in such a generalised way, as in your original question, is bound to cause confusion. When you say it's non-functional, you need to qualify that by saying "with keys, buttons and VC controls" because for people using an axis for the throttles it certainly is functional.

 

Have you raised a support ticket with PMDG? That's the only sure way to get a proper response.

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Saying something doesn't work in such a generalised way, as in your original question, is bound to cause confusion. When you say it's non-functional, you need to qualify that by saying "with keys, buttons and VC controls" because for people using an axis for the throttles it certainly is functional.

 

Have you raised a support ticket with PMDG? That's the only sure way to get a proper response.

Yes, support ticket has been filed. I am sorry for generalizing that post, but I assumed the whole forum post would be read. I would also guess there are people who use controllers like the xbox one for flying. the buttons on the controller are not usable for reverse pitch. normal throttle works with controller buttons though. I use the xbox controller for now as I can not afford a whole setup.

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Just confirmed the reverse issue here. Using an axis is fine, but dragging the levers in the cockpit is not (aircraft powers forwards).

 

Rob Smith.

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Just confirmed the reverse issue here. Using an axis is fine, but dragging the levers in the cockpit is not (aircraft powers forwards).

 

Rob Smith.

Thank you for testing and confirming that.

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This will never be fixed. PMDG says it is intended for only throttle quadrants to work. No joy for the rest of us with keyboards and controllers.

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This will never be fixed. PMDG says it is intended for only throttle quadrants to work. No joy for the rest of us with keyboards and controllers.

 

This is a complete falsehood. The second person to respond to your ticket actually offered to suggest it to the team to look into. After the response I sent to you (before his), I actually put it into our tracking system as something to look into. As noted in the other thread, though, we're bound by what the sim itself has to offer.

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