Some progress in FD mode

[erjdriver]

I'm sure everyone will be glad to know, that I'm making some progress in FD mode.

 

I had a problem where when I pressed the trimmer - it wasn't resetting the heading. I then found out that I had to disable the WPT mode on the 800 whatchammacallit. Makes sense.

 

Now I'm finding that when I press the trimmer, it doesn't reset the new altitude.

 

Is the "remembered" altitude - when you press the "A" button.

 

I would have thought if altitude-hold is enabled and I pressed the trimmer - it would now give guidance for the new altitude.

[Fishbreath]

Altitude hold is controlled by the collective brake.

 

In the real helicopter, holding in the collective brake lever (turning the brake off) allows you to move the collective. Releasing the collective brake lever engages the brake, locking the collective control at the current setting, and sets the autopilot's hold altitude to the current altitude.

 

Last I checked in DCS, the autopilot still applies its control authority to the collective when the collective brake lever is held in—so you're 20% down on available collective travel when altitude hold is engaged. You have three options:

 

1. Bind collective brake to a key, and hold it in while changing altitude. Because of the issue described in the paragraph above, this is functionally identical to...

2. Bind collective brake to a key, and tap it to set a new altitude when you want to change altitude. This also robs you of 20% of your collective travel, since you're fighting the autopilot—it's trying to hold the previous altitude.

3. Turn off the altitude channel while you're changing altitude, and re-engage it at your desired altitude. This gives you full climb performance, since the autopilot has no collective authority when the altitude channel is disengaged.

[erjdriver]

Thanks - and understood.

 

I guess for small altitude changes - the first one is good and the 3rd one for large changes.

 

I'm still a little bit confused by the FD mode.

 

e.g. I created a flight plan with a 90 degree turn...when I got there - the desired heading diamond bug moved (understood) but the bank indicator stayed the same - level.

 

Is this because I've the bank channel enabled?

[Fishbreath]

Huh. I'm not sure what to say there—if I have some time over the next few days, I'll play with it. You shouldn't need to turn off the bank channel.

[erjdriver]

Huh. I'm not sure what to say there—if I have some time over the next few days, I'll play with it. You shouldn't need to turn off the bank channel.

 

Yes I have all 4 channels enabled in FD mode and flying a flight-plan (PVI) with a dog-leg.

 

When I get close to the middle waypoint - the heading bug at the top swings to the new heading but the bank indicator remains at 0.

 

It's interesting that even with heading channel enabled - the heading bug swings...but not the bank indicator.

 

A traditional flight director would always indicate the correct bank/pitch/heading to follow the current flight-plan.

[erjdriver]

Any help here?

 

I've got bank, heading and pitch auto-pilot channels enabled.

 

Following a flight-plan - in route mode.

 

And enabled FD.

 

Anyone know why I'm not getting bank indicator.

[Looney]

Is the flight director set to route mode?

[erjdriver]

Is the flight director set to route mode?

 

Good suggestion - but I do.

 

I know because the heading bug at the top jumps to the new desired heading.

 

I get the 2 horizontal '=' symbols but it doesn't bank. maybe because I have bank auto-pilot channel enabled - i doubt that because I have heading channel enabled also and the bug jumps.

[Fishbreath]

Good suggestion - but I do.

 

I know because the heading bug at the top jumps to the new desired heading.

 

I get the 2 horizontal '=' symbols but it doesn't bank. maybe because I have bank auto-pilot channel enabled - i doubt that because I have heading channel enabled also and the bug jumps.

 

I should probably have some time to play with this for you tonight—I was flying a few nights ago to check out a few things for my guide, and was receiving bank guidance in FD mode (incidental to another thing I was working on). I'll try to characterize it.

[Fishbreath]

Okay, the three images attached show, from right to left, route guidance working. In the first image, I have a waypoint selected, but route mode off. I don't get any route guidance. In the next two images, route mode is enabled (note the HUD symbology with the speed offset, instead of the speed tape), and route guidance is working as expected, first to a waypoint off to my left, then to one off to my right. I did an air start to make sure I'm not flipping any switches normal people don't.

[erjdriver]

Okay, the three images attached show, from right to left, route guidance working. In the first image, I have a waypoint selected, but route mode off. I don't get any route guidance. In the next two images, route mode is enabled (note the HUD symbology with the speed offset, instead of the speed tape), and route guidance is working as expected, first to a waypoint off to my left, then to one off to my right. I did an air start to make sure I'm not flipping any switches normal people don't.

 

Thanks fish.

 

I think what I was doing wrong was - i wasn't flying close enough to the waypoint and it wasn't sequencing to the next waypoint. I was thinking it was auto-sequencing (because of the heading bug changes) - but it could be that the bug is pointing back to the wpt i just passed (i.e. 180) - i'll verify that by looking at the heading bug on the HSI next time.

 

On the last image, the FD is commanding a right turn with approx 10 deg pitch up. The speed offset is telling you you're going 20+ km/h too slow. And you're spot on with the altitude. Correct?

 

 

Now if you pitched up as directed - you would lose even more airspeed and gain altitude.

 

If you tried to fly faster (because it's telling you you're too slow) - you have to pitch down (cyclic forward) - that's opposite to what's commanded.

 

Help?

 

How would you fly the last FD commands.

[Fishbreath]

Thanks fish.

 

I think what I was doing wrong was - i wasn't flying close enough to the waypoint and it wasn't sequencing to the next waypoint. I was thinking it was auto-sequencing (because of the heading bug changes) - but it could be that the bug is pointing back to the wpt i just passed (i.e. 180) - i'll verify that by looking at the heading bug on the HSI next time.

 

On the last image, the FD is commanding a right turn with approx 10 deg pitch up. The speed offset is telling you you're going 20+ km/h too slow. And you're spot on with the altitude. Correct?

 

 

Now if you pitched up as directed - you would lose even more airspeed and gain altitude.

 

If you tried to fly faster (because it's telling you you're too slow) - you have to pitch down (cyclic forward) - that's opposite to what's commanded.

 

Help?

 

How would you fly the last FD commands.

 

The PVI-800 doesn't store information for transit speeds and altitudes—FD mode isn't commanding climb or descent, or acceleration or deceleration. The speed and altitude in route mode (whether out of FD mode or in it) are the speed and altitude from the last time the trimmer was pressed. The FD bars are the same. They're merely indicating the pitch when I last hit the trimmer.

[erjdriver]

The PVI-800 doesn't store information for transit speeds and altitudes—FD mode isn't commanding climb or descent, or acceleration or deceleration. The speed and altitude in route mode (whether out of FD mode or in it) are the speed and altitude from the last time the trimmer was pressed. The FD bars are the same. They're merely indicating the pitch when I last hit the trimmer.

 

Wow - that's good to know.

 

Then the "FD" on this aircraft is not really a traditional/modern flight-director....that's what was throwing me off.