Throttle trouble with Schweizer Heli

[DirkS]

Hello everyone,

I am building a Heli-Simulator and have connected custom controls via potentiometers and flightillusion's IO cards and fsuipc. All values seem to transport over nicely.

I seem to have some trouble with the throttle, though. I have searched this forum and found several hints, but ....here's the problem:

The Schweizer 269 does not have a governor and pilots have to watch and adjust rpm constantly - I'd like to build this also in the sim. I have saved a flight situation on the ground with engines off.

(sidequestion: Can I define somewhere the switch settings for this situation? e.g. Battery off, Generator off, clutch disengaged? When I start the engine, the rotor turns a little although the clutch is disengaged, so in reality it shouldn't. Can I set rotor rpm=0 together with starting the engine to get rid of that effect?)

When starting the engine with a little throttle, the rpm goes up too high, normally when starting the engine (with disengaged clutch of course) you would only go to motor rpm of 1500 max, but it goes to 3200rpm, the upper limit of the green take off range and cannot be adjusted. The value of 88C stays at ~4100. I can kill the engine by pressing F1 or go to max by pressing F4, it will slowly go back down to a value of 4000 (~3200rpm) after that and stays there.

I use offset 89A to get the throttle values between 0 and 12200 into the Schweizer Heli add-on. I have done the calibration through flight illusions software and they arrive ok in FSX through fsuipc, I have verified that through the lua-plugin. I can write values into 89A, but the value in 88C is always 4000 - apparently constantly overwritten from somewhere.

My suspicion is that I have not properly disconnected the throttle axis input in FSX (I can still press the F-buttons) that would be done through offset 310A, correct? How would I do that? Assign a button in fsuipc which would write 255 into this offset to simply disable all of them, just to be on the safe side? I understand that this would need to be done frequently - is there a permanent setting?

My ultimate goal is to manually and freely adjust throttle to influence motor rpm (and after enguipc aging the clutch rotor rpm with it) just like in the real Schweizer.

Thanks for helping, Dirk.

PS:The next upcoming challenge is the collective lever which also influences the throttle a bit. Any insights into this following question is greatly appreciated.

[Pete Dowson]

sidequestion: Can I define somewhere the switch settings for this situation? e.g. Battery off, Generator off, clutch disengaged? When I start the engine, the rotor turns a little although the clutch is disengaged, so in reality it shouldn't. Can I set rotor rpm=0 together with starting the engine to get rid of that effect?

You can assign several actions to a button, but only via editing the INI file -- you cannot do this in the on-line assignments. You might find it better to use a macro and then assign to the macro in FSUIPC.

I use offset 89A to get the throttle values between 0 and 12200 into the Schweizer Heli add-on. I have done the calibration through flight illusions software and they arrive ok in FSX through fsuipc, I have verified that through the lua-plugin. I can write values into 89A, but the value in 88C is always 4000 - apparently constantly overwritten from somewhere.

Hmmm. Sorry, I've no idea about that. If you write to 88C directly instead, how how does it take to change back to 4000?

My suspicion is that I have not properly disconnected the throttle axis input in FSX (I can still press the F-buttons) that would be done through offset 310A, correct?

No. If you are writing to 089A, then you don't want to disconnect the axis, because the whole point of 089A instead of 088C is to allow it to be disconnected liker an axis!! This is clearly mentioned in the document.

If you are controlling via 088C or via 089A, only, then you should vertainly have no aix assigned to that throttle in either FSUIPC or FS -- that will be overriding you otherwise (though if it keeps overriding there must be some jitter, as both FSUIPC and FS only act on changes).

Regards

Pete

[DirkS]

Hello Pete,

thanks for your reply. I have made some progress. I have found out that the Schweizer uses some fuctionality of the R44 model in the background. That led me to the assumption that there must be a governor somewhere like all robinsons - and it was true. Although there was no word of a governor in the Schweizer doc, there is one active and can be switched off with "shift + ,". Verified that through monitoring offset 826 through lua-plugin.

I have also seen that there are two inputs for the overall throttle. One is the throttle itself, one is the collective lever. Both add to same parts to the throttle value. e.g. 88C has a range from 0 to 16384 for throttle, 8192 come from the throttle lever, the other 8192 come from the collective lever and are added up. That leads me to the following questions:

1. How can I add a value coming from a wire to an existing value in an offset?

2. I have found offset 3AE8 "General engine 1 throttle lever position" ranging from 0 to 1, again half coming from throttle, half coming from collective. Can I write into these? What is the difference to 88C?

3. I am a little puzzled by the following thing: With the lua plugin I am able to verify the inputs for offsets 88C and 3AE8, but they only seem to work when in pause mode. My controls have no effect when unpaused - I think I have solved that somehow before but cannot seem to find it right now. Any idea?

THANKS!!!! Dirk.

[Pete Dowson]

1. How can I add a value coming from a wire to an existing value in an offset?

By program? Read the existing value, add the extra, write it back. But this seems so obvious I am obviously misunderstanding the question.

2. I have found offset 3AE8 "General engine 1 throttle lever position" ranging from 0 to 1, again half coming from throttle, half coming from collective. Can I write into these? What is the difference to 88C?

They are exactly the same information, populated at exactly the same time, in different formats. It doesn't matter which you write to. The 08xx offsets date back to FS95 and FS98 days and the others from FS2000 or later. All in the name of compatibility! ;-)

3. I am a little puzzled by the following thing: With the lua plugin I am able to verify the inputs for offsets 88C and 3AE8, but they only seem to work when in pause mode. My controls have no effect when unpaused - I think I have solved that somehow before but cannot seem to find it right now. Any idea?

No, sorry. FSUIPC and its Lua interpreter make no differentiation whatsoever between what they do when FS is paused versus unpaused. The only times when FSUIPC may not be updating things is when in menus and their modal dialogues. Even then the Lua threads might be continuing.

Regards

Pete

[DirkS]

Hello Pete,

thanks for the fast reply.

re 1: I am using the flightillusion IO interface to connect the wires and their config software for it. They then transfer the values to FSUIPC and I wonder where in this flow I could somewhere insert the programming. Could you give me a little direction to investigate on how this is typically/ideally done?

re 3: I thought more that the values are overwritten by FSX from somewhere when unpaused. Keyboard or Joystick, could that be? The cyclic and pedals work fine. It is just the throttle that gives me the trouble.

Thanks again, Dirk

[Pete Dowson]

re 1: I am using the flightillusion IO interface to connect the wires and their config software for it. They then transfer the values to FSUIPC and I wonder where in this flow I could somewhere insert the programming. Could you give me a little direction to investigate on how this is typically/ideally done?

Ah, so you are not writing the interface program to FSUIPC? You could instead use a Lua plug-in.

re 3: I thought more that the values are overwritten by FSX from somewhere when unpaused. Keyboard or Joystick, could that be?

The keyboard will not influence any values unless you press the keys to do so. But, yes, if you have a joystick connected, being processed by FS or FSUIPC, then of course that will overwrite values in normal unpaused mode unless you disconnect using 310A. However, values from joysticks are only used when they change. Maybe you have a jittery joystick pot? If assigning via FSUIPC you can set a larger Delta to overcome any jitter, but be aware that larger deltas give lower resolution.

Regards

Pete

[DirkS]

Thanks, Pete.

I have assigned a key in FSUIPC to write 255 into 310A when pressed - but no effect on the throttle behaviour. My controls only work when FSX is paused. It must be something else. Damn, I thought I had already solved that. Any other ideas? Or diagnostic approaches?

Dirk

[Pete Dowson]

Thanks, Pete.

I have assigned a key in FSUIPC to write 255 into 310A when pressed

That has to be done every 10 seconds or less. There's a timeout on it.

My controls only work when FSX is paused. It must be something else.

How are the controls connected? What is doing what? Maybe the program scanning them is not getting enough time when FS is running? Maybe it's a priority thing?

I really cannot picture what you are doing or how anything is connected. I can't really advise on anything more without knowing the bigger picture.

Test on a default aircraft, like the Cessna. Does the same thing happen there? If not, it is something to do with the way your add-on aircraft is programmed, and you need to deal with the author or support.

Regards

Pete

[DirkS]

Hello again,

I have followed your advice and tested with other aircraft.

For a Cessna I can manipulate the throttle (actually the mixture lever) while unpaused

For the Bell 206 Heli I can do that too (the collective lever moves)

For the R22 it does not work and also not for the Schweizer.

Apparently the throttle values are overwritten from somewhere when unpaused.

This is what I have done: I have connected some potentiometers and translate the values through flighillusions IO card into FSUIPC and map them to the proper offsets. They work, I see it when in pause mode.

Is there a chance to just disable any other input which might override my controls?

Thanks, Dirk.

[Pete Dowson]

For a Cessna I can manipulate the throttle (actually the mixture lever) while unpaused

For the Bell 206 Heli I can do that too (the collective lever moves)

For the R22 it does not work and also not for the Schweizer.

You do know, I assume, that the throttle controls for the "true" helicopter models in FS are NOT the same as the throttle controls in other aircraft? I think the Bell is actually modelled in FS using the basic prop engine, whereas the others will be using the later-added helo model.

Offhand I don't recall which controls are used in the helos, but I'll check now.

[LATER]

Yesits PROP PITCH to control the throttles in helos. The throttle controls operate the Collective.

Regards

Pete

[DirkS]

Hm, I am not that deep into FSX model structure, my apologies.

I was trying to help myself with the offset list.

I know the helo in question is always having the mixture lever at 100% whereas other aircraft have not.

I was looking for the PROP PITCH in the offset list, but am not too clear which offset it is. Is it something other than 88C and/or 3AE8?

May I ask where you looked that up?

I have a feeling that I do have the right offsets, because I see the helo throttle on the tip of the collective lever move correctly on the screen- but only when in pause.

I have two potentiometers - one is the helo throttle on the tip of the collective lever, the other one is the colletive lever itself. Each provides 50% of the overall helo throttle. Aren't there two offsets where I can simply feed those in? (sorry if I move towards wishful thinking)

Thanks again, Dirk.

[Pete Dowson]

I was looking for the PROP PITCH in the offset list, but am not too clear which offset it is. Is it something other than 88C and/or 3AE8?

The offsets for prop pitch are quite sensibly described in the offset lists as "prop lever", just as "throttle lever" and "mixture lever" are used for the other two. For each of the 4 engines they are in the very next offset to the main throttle offset.

May I ask where you looked that up?

In the kneeboards and other operational assistance references provided in FSX (where it gives the keystrokes needed), after selecting one of those helos -- and then verifying this by actually using the prop pitch key presses and watching the twist throttle operating, and also logging events in FSUIPC to check the controls being used by the keystrokes.

I have a feeling that I do have the right offsets, because I see the helo throttle on the tip of the collective lever move correctly on the screen- but only when in pause.

I suspect that is only because the code operating the helo model isn't operating when paused.

I have two potentiometers - one is the helo throttle on the tip of the collective lever, the other one is the colletive lever itself. Each provides 50% of the overall helo throttle.

The collective is surely the actual pitch of the blades? Oddly controlled by the throttle inputs. I simply do not understand why two pilot controls each contribute 50% to one helo control. That is surely wrong? How is that supposed to work? Perhaps you are referring to RPM -- obviously a flatter pitch will allow the RPM to increase, and vice versa, but that isn't throttle control.

Aren't there two offsets where I can simply feed those in? (sorry if I move towards wishful thinking)

The throttle and prop pitch offsets are clearly labelled "throttle lever" and "prop lever". Sorry, I thought this was evident. Or am I misunderstanding your questions?

Perhaps you need to exchange ideas with other Helo fliers. There are plenty around, I'm sure. I've never heard of anyone having so much difficulty as you, so I'm sure it must be all a bit of a misunderstanding. Have you tried flying the helos with normal assignments of controls rather than via offsets? (All FSUIPC does when you write to the offsets is send the controls to FS which your levers would do in any case if so assigned).

Regards

Pete

[DirkS]

I think we are getting there!!

Yes, I actually mean RPM, that is what I want to control. But the collective lever on screen is labeled "throttle", so I used that synonymously. Adding to confusion - sorry about that.

The thing with the 50% I have seen from FSinterrogate. The RPM knob at the collective lever tip contributes 50% to Max RPM

The collective lever when pulled, changes the blade angle (I have not seen where this needs to be sent, if at all), but simultaneously adds the other 50% to RPM.

When I turn the throttle knob at the tip of the lever, FSInterrogate tells me that

088C ENG1 throttle lever changes from 0 to 8240

3AE8 ENG1 (Recip./General) Throttle lever Pos changes from 0,00291 to 0,50291

When I in addition lift the collective lever FSinterrogate tells me that

088C ENG1 throttle lever changes from 8240 to 16336

3AE8 ENG1 (Recip./General) Throttle lever Pos changes from 0,50291to 0,99707

332E Throttle (common) axis input

I just would like to replay this with my potentiometers instead of a joystick.

Could it be a joystick assignment that overrides my inputs when unpaused?

Dirk.

[Pete Dowson]

The collective lever when pulled, changes the blade angle (I have not seen where this needs to be sent, if at all), but simultaneously adds the other 50% to RPM.

Well the latter is a result of the former -- a flatter blade allows the rotor to spin faster, less air resistance.

When I in addition lift the collective lever FSinterrogate tells me that

088C ENG1 throttle lever changes from 8240 to 16336

3AE8 ENG1 (Recip./General) Throttle lever Pos changes from 0,50291to 0,99707

Well that is what I'd expect with the collective being controlled by the throttle control.

I just would like to replay this with my potentiometers instead of a joystick.

Could it be a joystick assignment that overrides my inputs when unpaused?

If you have multiple inputs to any control, they certainly will interfere -- but only if they are seen to be moving (jittering, perhaps). Both FS and FSUIPC only take notice of changing inputs, not static ones.

Regards

Pete

[DirkS]

ok, I have now used the axis calibration feature to check whether there are any inputs coming from somewhere. I have switched off the joystick control in FSX by unchecking the box in the calibration tab of "settings, controls"

BTW: Apprently this was more clear in FS9, there was a pulldown menu with the command "disable joysticks", now in FSX it is the method described above, correct?

When I let FSUIPC search for joysticks there should be nothing, because no joystick is connected and my potentiometer controls go through an interface directly to FSUIPC. But it finds a Joy#17 with Axis#T and Joy#18 with Axis#N after switching back and forth between pause and unpause. Could that be the mechanism overwriting my values? How can I find out where they come from? And get rid of them?

Thanks, Dirk.

[Pete Dowson]

BTW: Apprently this was more clear in FS9, there was a pulldown menu with the command "disable joysticks", now in FSX it is the method described above, correct?

Yes, but it is more flexible the new way -- you can disable each set of controls separately. Make sure you select them in the drop down to disable them.

When I let FSUIPC search for joysticks there should be nothing, because no joystick is connected and my potentiometer controls go through an interface directly to FSUIPC. But it finds a Joy#17 with Axis#T and Joy#18 with Axis#N

Joy 17 and 18 are activated by programs writing to the FSUIPC joystick interface (mainly used for PFC devices by my PFC drivers) at offsets 3BA8 to 3BC4. (Please see the offsets list). If your hardware driver is changing those, it is obviously intending you to assign through FSUIPC's axis assignments. So why don't you?

Could that be the mechanism overwriting my values?

No, because unless you assign them, there in FSUIPC's axis assignments tab, they are ignored.

Regards

Pete