707, DC-8 autopilots weave in VOR mode?

[jimhalinda]

I did some VOR to VOR flying in the HJG DC-8-40 tonight, and noticed that when following a VOR in autopilot mode, it would overshoot the VOR beam, weave back across it, overshooting again, and just keep weaving back and forth. (You could really see the path in map view)

Tried it with the HJG 707-420, it did the same thing.

Did the old autopilots really have that much trouble following a VOR beam? I was at 31000 feet, and even approaching from 150 miles away it would do this. And it wouldn't settle down either, it kept overshooting by the same amount again and again.

Some other freeware jets did this (Meljet 777-300, POSKY 747-200) and some did not (SGA DC-9-30, Vistaliners L-1011, Mike Stone's Caravelle). The default 737-400 did not weave.

Just wondering why I see this in some jets and not others.

I've pretty much used GPS or INS navigation exclusively on most jets I fly, and never noticed this wandering tendency doing it that way.

Any comments appreciated.

Regards,

Jim

[aerofoto - HJG Admin]

I know what you mean.

Most FS aircraft will weave in very slowly decreasing increments for the first few minutes upon locking on to any VOR .... more so if you if you intercept it too sharply or activate VOR LOC too early or late.

This seems to be a peculiarity of FS.

I recommend using HDG HLD, or even manual flying to get yourself pretty much right on the true VOR beam .... then activiate VOR LOC once you're established and stable on the line.

Your FS aircraft might then want to weave very slightly at first .... but .... probably not so much before it settles onto the course after a few minutes or so

I've never experienced any out of the ordinary weaving with DC8 or B707 (or the CV880 & CV990 either for that matter) during VOR intercepts and course following in AP controlled flight.

Mark C
AKL/NZ

[Harerton Dourado - HJG]

As far as I know the real thing is not so quick in capturing a VOR course too.

But this weaving thing is an FS issue. It was worth in FS2002!

[johndetrick]

You are so right about that!!!