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DC-3 Autopilot (Read 936 times)

Jul 22^nd, 2009 at 9:39pm

RacingLad Offline
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Can anyone show me how to operate the autopilot of the DC-3 in terms of heading and maintaining altitude...

Saludos!

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Reply #1 - Jul 22^nd, 2009 at 10:09pm

Brett_Henderson Offline
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The DC3 doesn't have an altitude hold.. it has an attitude hold... i.e. pitch hold. MSFS tries to replicate this as a vertical speed hold.

This is adjusted on the autopilot part that resembles an attitude indicator. You'll see how pitch (actually vertical speed) changes, when you change that setting.

As for heading.. you'll see a part of the autopilot that resembes a heading indicator. It has two 360 degree indicators. One IS a secondary heading indicator (you'll see that it is in synch with the primary headinging indicator.. will drift with it, and reset with it) The other 360 indicator is in effect, the heading bug. The autopilot will turn until the two are lined up.

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Reply #2 - Jul 22^nd, 2009 at 11:20pm

Boikat Offline
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All things considered, it's more of a "semi-automatic pilot". Tongue

"I reject your reality, and substitute my own" Adam Savage, Mythbusters

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Reply #3 - Jul 23^rd, 2009 at 3:31pm

Staiduk Offline
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Can I throw something in Brett? Not that this'll help much, but a mistake people commonly make with the DC-3 is trying to engage the autopilot before the aircraft is properly trimmed for flight. In more modern aircraft, this doesn't make much of a difference, since the AP takes over and drive the aircraft (in a very unsublte manner, IMO Grin

). The Sperry autopilot works from an initial position based upon the aircraft's current trim. In other words, you get to your altitude (or off the ground, like a lot of sim pilots) and turn the thing on; you'll be wiggling and porpoising around forever. The trick in using the system is to properly trim the aircraft first, then turn it on. The ship'll hold that trim perfectly.

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Reply #4 - Jul 23^rd, 2009 at 6:16pm

Brett_Henderson Offline
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Excellent point, Staiduk... That's how that old AP is used in real-life.. because it's an ATTITUDE hold. When you get the aircraft trimmed (level-flight, climb or descent), that's obviously the attitude you want.

When I fly the FSX DC3, I'll hand-fly any transitions, and then engage the AP when trimmed and level. That kinda skips me past the flaw, that the FSX attitude hold is actually a vertical-speed hold. For the sake of simming, that's OK.. even if you DO make your transitions with the AP, because for any given power-setting, attitude WILL translate to vertical-speed, eventually. It's just that a transition would be a little "porpoisy" if it were a true attitude hold. A transition from cruise to climb requires a pitch change... if your only reference is vertical-speed (ala FSX), that pitch will change as airspeed bleeds off, in order to maintain that vertical-speed. With a REAL Sperry, that transition would be pitch alone, and then vertical-speed is the variable, so it's never "locked" onto an altitude.. you still gotta tweak the real Sperry.. whereas the FSX Sperry WILL "lock" onto an altitude, because zero vertical speed assures that.

Roll Eyes

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Reply #5 - Jul 24^th, 2009 at 1:40pm

Staiduk Offline
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I've actually flown a DC-3...once, for about 5 minutes, a long time ago. The skydiving field I belonged to (Swoop Skydiving, Grand Bend, Ontario) had one they'd drag out on Saturdays (50 jumpers in the air at once! Whoopee!! Grin

) I finangled my way on for a fuel run and the pilots let me take her for a few minutes. I was surprised at how responsive and easy to fly such a big plane was. From what I understood; the Sperry is almost never used anyway since once she's cruising comfortably control is fingertip-light. I'd be interested to know if the same holds true for long-ranged flights. Probably. In any case, even on my Pole-to-Pole FS9 flight a few years ago (aborted - engine blew up over Chile), I only ever used it to run to the bathroom. Grin

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