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FLCH like real planes! ACHIVED READ PAGE 3

Designing a stable autopilot is one of the hardest things. Need help?

Re: FLCH like real planes! ACHIVED READ PAGE 3

Postby Octal450 » Sat Mar 11, 2017 8:02 pm

I'm working on my own VNAV system ;) It will be connected to my FMS framework (not yet available, in development)

It uses this FLCH controlller.

viewtopic.php?f=4&t=31793

I have working calculate T/D, and target descent rate to meet altitude, and working waypoint altitude constrictions at climb/descend.

I'm just needing to program a way to calculate descent, if you are passed T/D, or the required descent cannot be met. This should be working soon.

Regards,
Josh
Waste of time. Goodbye forever.
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Re: FLCH like real planes! ACHIVED READ PAGE 3

Postby Hooray » Sat Mar 11, 2017 8:52 pm

note that the problem you are tackling is not as one-dimensional as it may seem, e.g. consider changing winds, speed/altitude restrictions, weight & balance (fuel) and different aircraft configuration (flaps, slats, gear => "drag required").
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Re: FLCH like real planes! ACHIVED READ PAGE 3

Postby Octal450 » Sat Mar 11, 2017 9:21 pm

I am fully aware.

I am first tackling the basic VNAV functions, and once I can make a profile for descent, I will then use the FMS SPD mode, and modifying the profile, to correct for those things.

I already have altitude constraints working, speed constraints not yet, as I can't find any place in Route manager for this, so I won't do it till me FMS system is complete.

Drag required will appear when the aircraft can't keep on profile, without the airspeed being higher than target, and thrust is close to, or at idle.

Don't worry, I've done about 4 months of research in VNAV. Now it's just getting it working/programmed.

And that article you linked is wrong.
The 777 has proper FLCH
ITAF equipped planes have proper FLCH
757, 767, 747-8i have proper FLCH
A330-200 artix private has OP CLB/DES (FLCH)

A few other aircraft have a speed by pitch function which is similar.

I also have varying altitude capture. At higher V/Ss it captures farther from target altitude, at lower V/Ss it captures closer to target altitude.

Josh
Waste of time. Goodbye forever.
Octal450
 
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Re: FLCH like real planes! ACHIVED READ PAGE 3

Postby Hooray » Sat Mar 11, 2017 9:35 pm

See the references in the aforementioned wiki article, specifically: http://www.davi.ws/avionics/TheAvionics ... Cap_15.pdf
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Re: FLCH like real planes! ACHIVED READ PAGE 3

Postby Octal450 » Sun Mar 12, 2017 12:13 am

Thanks for that!
I will check it out.
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