Throttle flutter

[carpenter]

Problems with my motorized throttle.

I’m building an auto throttle with use off some dc motors and opencockpit hardware.

All the hardware and software works fine.

I will use the throttle in combination with PMDG 737-800 software, but what I see is that there is a lot off flutter on the PMDG throttle. For the positioning off the DC motors levers I read offset $089a (lever 1)

When I make the read out value from this offset visible I see a flow off data and the values in the flow jumping with difference of 1000 or more (3 or 4 times within a second).

(Value between 0 – 12560)

This explain possible the flutter.

Question: What can I do on this problem.

Has FSUIPC possibilities ?

Do I use the wrong offset address

I use MS FS9 and FSUIPC 3.75

Thanks Henk

Netherlands

[Pete Dowson]

I read offset $089a (lever 1)values in the flow jumping with difference of 1000 or more (3 or 4 times within a second).

This is with an analogue throttle lever connected and without AutoThrottle engaged? If so then it sounds like your throttle hardware has a jiyyer -- possibly a bad/dirty potentiometer, or poor / unsmoothed power supply?

If you mean when the PMDG autothrottle is operating, then I assume this is the PMDG code trying to maintain steady thrust / N1 / N2 settings in slightly varying conditions.

Why do you mention PMDG in particular? Doesn't it occur with default aircraft?

What can I do on this problem.

If you are using the values to directly control your motorised throttle it sounds like you need to do some smoothing or less frequent sampling.

Has FSUIPC possibilities ?

No.

Do I use the wrong offset address

No.

Regards

Pete

[carpenter]

Thanks Pete for your quick response.

My throttle works fine with all the analogue throttle lever potentiometer connected.

The flutter that I see is with auto throttle engage.

And more specify when I turn the IAS button from my MCP say from 180 knots to 250 knots

or for example in the other direction.

The speed runs nice to 250 knots but when look to simulate PMDG throttle on the screen I see the throttle levers sometimes quickly up and down jumps.

When the aircraft reach the 250 knots the throttle is more stable and completely stable after 30 seconds when I reached 250 knots.

Normal I have no problems with this jitter. I do not see anything wrong during the flight.

But when I connect my motorized auto throttle it’s not nice to see the throttle levers move

small jumps up and down.

With a standard MS FS aircraft I do not see this flutter / jitter.

An the throttle is completely stable.

Regards Henk

[Pete Dowson]

The flutter that I see is with auto throttle engage

...With a standard MS FS aircraft I do not see this flutter / jitter.

And the throttle is completely stable.

It is evidently related, then ,to the way the PMDG autothrottle works. They will probably tell you it is more realistic and provides a better A/T than the FS default.

Normal I have no problems with this jitter. I do not see anything wrong during the flight.

But when I connect my motorized auto throttle it’s not nice to see the throttle levers move

small jumps up and down.

There's only two possible solutions I can think of, then-- either smooth the values before sending them to your motor, or use a different aircraft. I use a PMDG model 737 but not with their autopilot, but Project Magenta instead. I don't think that affects the throttle values so fussily.

Regards

Pete