Howdy guys,

some of you may have watched my INS tutorial on youtube (blub77) that I made in 2007.
I'm a lover of old aircraft, even though I was just born when those loud, dirty beasts were vanishing from european skies - but I still remember when I was younger and riding as a passenger on 737-200s. The noise when flying, the rattling and shaking of the whole cabin when landing etc. Lufthansa operated them till the mid-90s and Aloha in Hawaii still flew them in 2004. Too bad the good old jets, like 727, 707, 732, DC-8s (Ooooh captain sim, please build one!!!), L1011s, DC-10s are vainishing

Now I'm at least a private pilot, about to become a Flight Instructor and maybe one day will work as a commerical pilot. But my fascination for "old style" flying remains. Hence i've done alot of research to get knowledge of the workings of those old systems.

This is why I decided to make a tutorial on how to use the SP77 Autopilot (once it is operational) and maybe also work on a tutorial on how to navigate with the 737 from one airport to another just by using VORs/NDBs/DMEs.

SP77 Tutorial:



This is the SP77. Blue numbers indicate the flight director functions, red numbers are for the main autopilot.

The flight director (FD) and the autopilot (AP) are NOT connected. While the autopilot is driving the controlsurfaces when activated, the FD can be activated/deactivated independently and is just for reference.

Quote:


How does the Autopilot now work?
The autopilot has not too much functions but yet is very usefull when you need it. It basically works on the principle of CWS (Control Wheel Steering) and will maintain "parameters" set by you.

For example: You're just departing Edmonton Airport in Canada with a fully loaden 737-200 of Canadian North, heading to the north. As you know, aircrafts are flown by pitch+powersetting and airspeed. You fly V2 + 15 let's say up to a certain altitude.
Now you activate the Autopilot (ELEV + AIL). The autopilot will now maintain your current heading and your current pitch. Since you control airspeed with the pitch, you see that your speed is increasing, but you want to climb with 220kt. So you pull back on the yoke until you maintain 220kt. Let's say this gives us a pitch of 9°. If you now release the yoke, the autopilot will trim the elevator trim in order to maintain 9° of pitch. Now matter how fast you're going or what the engines are doing, it will maintain 9° of pitch UNLESS you change something. And this works the same with your bank angle.


Let's go throught the modes of the Autopilot:

1. Your Mode Selector: Here you can select different Autopilot Modes:

MAN - will maintain current heading if HDG switch is in the middle position or will maintain a bank set by the yoke if the AIL switch is ON and HDG is OFF. If HDG SEL is selected the airplane will fly the heading selected on the captains HSI.

VOR/LOC - will intercept a vor radial / localizer. Until the localizer/radial becomes alive the autopilot will maintain current heading or follow the heading bug depending on the position of the HDG switch

AUTO APP - same as VOR / LOC but now the autopilot will intecept the ILS, it will also capture the glideslope and follow it down

MAN G/S - same as above but with a higher sensitivity and also allows the AP to intercept the G/S from above

2. A/B/A&B - with this switch you can select the hydraulic system which operates the Autopilot. Either A or B or both.

3. Heading Switch:

OFF - heading is off, Autopilot is only controlled by CWS

Middle Position - Autopilot will maintain current heading

HDG SEL - Autopilot will be driven by HDG bug on captains HSI

4. AIL Switch Engages/Disengages the aileron channel of the autopilot
(so to say the on/off button of the autopilot)

5. ELEV Switch Engages/Disengages the elevator channel of the autopilot
(so to say the on/off button of the autopilot)

6. Altitude Switch:

OFF - CWS will fly pitch commands by yoke

ALT HOLD - autopilot will hold the current altitude. When higher forces on the yoke are detected the switch will return to the OFF position

TURB - higher sensitivity setting, the autopilot will maintain current pitch during turbulences



The Flightdirector:

The flight director is used for reference on the ADI. It has no control over the autopilot:

1. Mode selector:

OFF - FD is off

HDG - FD will give bank information on how to fly a heading selected with the HDG bug

VOR/LOC - FD will give bank information on how to fly a radial/localizer

AUTO APP - FD will give bank information on how to fly a Automated approach

MAN GS -  FD will give bank information on how to fly a Automated approach. Higher rates will be used.

GA - FD will provide pitch and roll information for a Go Around (pre-defined pitch attitude in combination with GA thrust)

2. ALT HOLD ON/OFF - FD bar will give pitch information to hold altitude. When ALT HOLD is on, the Pitch(3.) Selector has no influence on the FD bar.

3. PITCH CMD - will set the pitch bar on the FD to a certain pitch.

This is it so far. This tutorial is in no way complete, nor final nor correct. It would be good if someone could verify this information and if necessary correct it.
I will - when it's working and my time schedule permits - make further tutorials on using the 732s autopilot of the CS 732.

Regards
Johann

Very Good!

Before reading this I didn't realise the FD was separate to the AP or even that it was the FD!

Too much 737NGX flying! 

Thanks
Ben435

Hi Johann,

A very belated "Thank you" for the INS tutorials; I've watched them last weekend after installing the INS in the 727 - finally it made sense to me.

lucatrader wrote on Apr 16^th, 2012 at 11:54pm:


Lucatrader:

This thread is for SP77 Autopilot. The INS (gauges) will not work for navigation on this 737 (as far as I know).  The INS references above are to other aircraft, but not to this 737.

Thanks. 

I just did a test, with the CS 737-200, and when I turned the Autopilot Mode Selector switch to VOR, while still climbing, it turned to intercept the VOR track just like it should. I did not need to press the ALT HOLD switch to make it track the VOR.

No luck I´m afraid. Reinstalled with same result and ticket response was that it was going to be forwarded to the developers.

I still find hard to believe that somehow the a/c has to be in ALT HOLD mode for the autopilot to intercept and follow any VOR radial on VOR/LOC mode.

It is a pity as I find the external model is quite good.