VC10 autopilot

[forthbridge]

Hi Guys

Running FS9. Ben, if it's a misunderstanding of the autopilot, then I'm to blame - but I've flown lots of hours without this ever happening before......

Basically, I only use authothrottle if I am on an approach, otherwise I climb to around 1500feet and engage AP1, the yaw dampers and 'alt hold' - once the aircraft stabilises I then select climb rate with the datum adjust (or descent) and adjust throttle manually to maintain desired speed.

Robbie mentions a 'hunting' which is a good description - although in my situation if I do not take corrective action the aircraft will continue to descend.

I have numerous flight recordings of the vc10 taken with FSRecorded with some formation flying, and the autopilot in those instances was quite capable of a:holding the lead aircraft at an altitude and b: allowing any following aircraft to juggle around into position in formation.

At present I've only got the HS748 and Andover installed (as well as the vc10) and the autopilot is flawless on that.

As for flap setting I use 20deg takeoff, and as I pass flaps up speed they are retracted. I always aim for about 270 KIAS climb speed. the A/c flies well manually and can be held with the trim wheel to the desired climb, but at any altitude, once autopilot is engaged, it starts acting strangely. This has not happened previosly.

[speedbird591]

I haven't experienced this, Jim. And, like yourself, I'm using FS9 and Vista. It seems odd that you are using the same procedures that you've always used and it's only now that you are having problems.

A couple of points, though. I'm pretty sure that in RW the AP isn't normally engaged until levelling off in cruise and that the climb is managed manually. I certainly don't think that the datum adjust is used. I think that is only for adjusting flight level when in cruise. However, I do usually select the AP on when established in climb, but not the ALT hold. If the AP is engaged then you can use the pitch wheel to adjust the climb. I expect you already know that the climb rate should be less than 500 fpm when engaging ALT hold. Personally, I level off with the pitch wheel before engaging.

Dan should be able to come up with the answer because he has a genuine copy of the BOAC VC10 flying manual. Don't you, Dan???

Ian

[DanKH]

Do I?

Oh yes that's right, I do .... let's see..... :think:




Nope, no mention of DM's AP-behavior sorry

[forthbridge]

Cheers Ian

I've not flown too many long distance sorties with the '10 recently and thus don't often climb to above FL200 - whenever I do, I use the pitch wheel without alt hold until I reach the desired height. However, I have just performed a 'perfect' climb to FL200 using the pitch wheel. IAS 284 kts, and I levelled the A/C off to about 100fpm (virtually level) - left it there and stabilized speed at 290Kts. I then engaged ALT HOLD. The A/C dipped about 10 feet and stabilized. After a minute, I used 'Datum adjust' to initiate a small climb (500fpm+). This is the method I have always used to move up/down a few thousand feet from any given level above about 3500AGL. I have never had any problems. However, as I mentioned, I selected +500 on the datum adjust. (As you do this the pitch wheel moves in accordance with your up/down selection) - except the aircraft began to descend from FL200 - not climb!!!!

I could easily use the pitch wheel and ALT HOLD with a zero selection on the datum - this will maintain height - but whenever I use datum adjust it seems to do it's own thing. Were it not for the fact that I have exclusively flown the VC10 this way (down to landing it using the datum adjust) I'd be less perplexed!

Quote from the DM Manual:
4 : ALT
Altitude hold will hold the current altitude by holding Vertical Speed at zero.
Altitude hold does not allow the selection of a target altitude, but the held Vertical Speed can be adjusted to hold a steady climb or descent using 'DATUM ADJUST' (10).

Unless I read it wrong, this is what I've been using it for.....

The problem of course is that as soon as the pitch changes, speed increases, etc etc.....

***EDIT - just preformed a reboot, and this time in G-ASIX, climbed to 5000 feet, held alt perfectly, engaged 700+ on the datum and the aircraft descended. :brick:

Maybe it's all those pax bouncing around singing about 'Caledonian girls'????

[DanKH]

It seems to me that there is something in the cfg-files.

I only fly the Super... have you experienced the same thing with the C1k, 1105, 1101 or 1103?

Or doesn't that matter?

[forthbridge]

HI Dan

I've every model installed, and each do exactly the same. I'm just going to try the autopilot on an ILS approach to see if that works.....

[DanKH]

can you give me the date of the CAP-file in the panel folder? I'll check againt mine when I come home from work...

[forthbridge]

HI Dan,

Both 18 Apr 08. (Do you mean the CAB files??).

Autoland performs perfectly. Seems to just be the datum adjust that is causing the problems.

[Garry Russell]

I'm sure he does Jim

Garry

[Hot_Charlie]

If the jet is wondering up and down + or - 100' it is about spot on