Mixture control -- DC-3

[Guest DC3 Pilot]

Hi Group,Using the keyboard with my M.A.A.M-SIM DC-3, I find that it takes about 25-30 clicks to move the mixture levers from the top (Full Rich, FR) to the bottom (Idle Cutoff, IC). Of course, using the mouse (or my CH hardware levers) it's a smooth transition. My question is whether the mixture is actually leaned on a smooth curve, or has just 4 positions (FR, Auto Rich (AR), Auto Lean(AL), and IC) that are achieved by moving the levers to the middle of the indicated area. I've tried listening to the sound of the engines as a way to tell, but until I get toward the bottom of the AL bracket it's difficult to discern any significant difference. Finally, the "Auto" in AR and AL suggest that some on-board system is at work to optimize the fuel flow with the given setting (AR or AL). Is that the case? Or is it entirely up to the pilot to move the lever within AR and AL ranges to achieve the desired fuel flow? Many thanks for the clarification on mixture control.Best regards,Gary

[Guest wji]

Search MAAM R4D Manual written by Bill Rambow for 'mixture':Some examples of twelve hits starting at p.22:"The Prop, Throttle, and Mixture Control Levers feature drag-able hotspots, where holding down the left mouse button allows you to move, or "drag" the knobs to any desired position in its travel.Only the Prop Pitch,Throttle, and Mixture Control Levers are adjustable in the partial quadrant.CONTROL ANIMATIONS The VC flight deck includes a number of animations that mirror the controls in the 2D panels, as well those of your yoke or other control devices. Animations include the yoke; rudder pedals; throttle, prop and mixture levers on the quadrant; the gear lever and bail, wing flap lever, and cowl flap levers." etc., etc..See also DC-3 Reference.htm and Checklist.htm (*Auto-lean)We lean using CTRL+F2 while monitoring engine RPM.

[Guest SPOFF]

HI Gary: This is how the mixture works in real life AND in the SIM. "Listening" to the sound of the engines is the way I adjust the mixture. At anything below 5000 feet ASL or so, you won't see much difference in sound other than the engine dying altogether if you pull the mixture levers pretty near all the way down. To see,.. or should I say..HEAR, how it works, take the plane up to some altitude above 5,000 feet..the higher the better to HEAR the difference in engine sound when you lean the mixture...then level off. As you gradually pull/lean the mixture, (I drag with the mouse) you will notice the engine sound "speed up". This is what you are looking for. At some point, the engine will start to "Faulter". Ease the levers back up a tad, until the engine smooths out again. That's where you want to be for that altitude. After that excercise, you can get into Manifold Pressure and Prop settings to make it as complicated as you want. SPOFF

[Guest DC3 Pilot]

Many thanks SPOFF . . . exactly the info I was looking for. I assumed the mixture levers were incremental, but didn't think about altitude as having an influence on verifying by sound. Question: Why does the label beside the mixture levels says "auto" rich and "auto" lean? You're doing it manually -- as you described -- and there is nothing automatic about it, no? Just curious.And, yes, I do work with props and throttles . . . this is a pretty amazing simulation and I try hard to make it as realistic in application as I can :-)Best,Gary

[Dark Moment 0]

In The Real McCoy there are detents for autorich and autolean. See my/Dave Bitzer's add-on for the MAAM-SIM bird that simulates that:http://www.swiremariners.com/dc3FS9.htmlMarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest DC3 Pilot]

Hi Mark,So is this right?1) In the Real McCoy there are four distinct settings (and no sliding in between) -- Full Rich, Auto Rich, Auto Lean, and Idle Cutoff. The detents allow selection of AR and AL.2) In the simulation, there are an infinite number of settings, i.e., a smooth transition with the levers from FR to IC. Selecting a good setting can be done per SPOFF's suggestion.If so, and just for one with great curiosity about all aspects of DC-3 operation, with the Real McCoy if you set the lever to the AR or AL detent, does some mechanical governor take over and automatically adjust the fuel flow on some basis such as pressure altitude? Or are these just fixed settings so that you have only two real choices, AR and AL?Thanks for the continuing education.Best,GaryP.S.: The sextant works beautifully. Super job on that!

[Guest SPOFF]

HI AGAIN GARY: I can't say for sure weather the (Real) DC-3 mixture can be regulated "Automatically" within some "Zone" based on pressure altitude with the mixture levers. My guess is the Detents are there as a general reference so the pilot can know about where the levers are by feel.In a Cessna, Piper, or other Small Common GA aircraft, the mixture adjustment is done BY the pilot at his descretion, and the adjustment is "Infinate". There is NO "Automatic". It's been awhile since I've flown "Real" so my memory may be off a bit. Incidently, I havn't noticed whether the DC-3 has an EGT Guage or not. (Exhaust Gas Temperature). This also can be used as a reference for leaning. "Generally" you lean to achieve "Peak" EGT for a given cruise speed and altitude and then enrichen slightly, but this is for a Cessna. The engines in a DC-3 may have a much different requirement. SPOFFEDIT: Maybe I should go read the DC-3 manual myself. I hate reading manuals. I won't ask for directions on how to get somewhere either... until I get "really" lost. It drives my wife nuts but she just doesn't understand: Let's FLY this bad boy first and read the book later...The way it should be! It's a GUY thing.

[Guest kennethg]

Your memory is correct: GA aircraft (for the most part) all have purely manual mixture controls. Depending on what instrumentation is installed, you lean for peak EGT, or just pull the control back towards lean until the engine runs rough, then push it forward towards rich a little to smooth it out. The DC-3 has a different carburator in that it senses altitude, so it can judge what the correct mixture is and the pilot doesn't have to hunt around for it. Since the mixture is automatically set, all the pilot has to do is tell the carb what sort of mixture is needed, based on power required. The 4 settings are full rich, auto rich, auto lean and idle cut-off. The reason for the detents is to ensure the mixture control is always placed in the correct spot to allow the carb to work correctly. The carb is a purely mechanical computer and when the mixture control is in between settings, it messes up the fuel metering. In essence, the mixture control suggests to the carburetor what the correct mixture should be, but it's the carb itself that determines what that mixture will be, without any direct input from the pilot.

[Guest SPOFF]

HI KEN: Thanks for the description of the DC-3 Carb mixture regulation. Actually, last night I thought of an alternate possable explanation for the mixture "Detents". I reasoned that perhaps the detents were there to prevent the mixture levers from assuming a New position (on their own), as a reaction to "Vibration".A few years ago, I had a chance to fly right seat in a FORD Tri-Motor that was on tour around the country. The throttles were held in cruise position by a "Thumb Screw", to prevent them from assuming a new position on their own. When the pilot came around on "Final" to land, he just released the thumb screw and the throttles started "Creaping" toward idle by themselves... All the way down to touchdown. After releasing the thumb screw, the pilot never touched the throttles again until we taxied off the runway. Regards: SPOFF

[Dark Moment 0]

GaryGlad to see Ken jumped in with an answer for you there.SPOFF, I like your 'creepy' tale. The real DC-3 has friction locks (not modelled on the MAAM-SIM or default, sorry) to stop that happening. But that sounds like a fun (if somewhat random!) way to make an approach.MarkMark "Dark Moment" BeaumontVP Fleet, DC-3 AirwaysTeam Member, MAAM-SIM[a href=http://www.swiremariners.com/cathayhk.html" target="_blank]http://www.paxship.com/maamlogo2.jpg[/a]

[Guest allcott]

As a complete aside, but aan indication of how far we have come, the new Wings of Power Heinkel 219 Owl actually has throttle locks!Ye gods! they'll be shipping ziploc bags with burnt engine oil next!Allcott