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Question on DC3, C46, DC4 and others

G

guitar0633

Members +
Finally I have a great forum like this to ask a question and it's one I have wondered about for some time.

I like to play Air Hauler 2 and I use these wonderful planes in my company. I just got done flying this great DC3 version 3 and I just love it.

I also am a huge fan of Ice Pilots show.

So, how much auto pilot do these birds really have?

On Ice pilots I have all episodes and I have never seen those guys turn the planes by turning an autopilot hdg knob. When I fly these awesome birds I don't want to use options these real planes don't have. I realize these planes had basic AP's called, what was it, spiro's or something? Were they just able to hold a heading and altitude once the pilot hot it there?

I realize that planes obviously get updated as much as possible, but are the Buffalo planes, for instance, able to actually turn with a heading knob, or decend a certain feet per minute by an AP control?

I have heard Buffalo pilots saying they did not have fancy do-it-all AP's like modern jets, and I don't want to use anything more than they have.

How would an old plane like a C46 be upgraded with a unit that could actually move the flight surfaces if the plane wasn't built with them?

What kind of a unit would need to be installed in an old plane like these that could actually control the rudder and elevator and such?

I wish Manfred and the team could put a note with the plane explaining what controls are there for convenience and what real pilots have available in the real planes.

I am referencing Buffalo because they obviously use these old birds for work to this day.

To best imitate reality, should I take my plane up to altitude and heading myself then turn on AP? Should I follow the gps by actually turning myself or hit the gps button in the DC3 and let the unit turn the plane automatically. Is this even possible in these planes?

I wish so bad I could talk to a Buffalo pilot for ten minutes, I would bombard him with questions, lol.

I just want to fly this awesome DC3 (and C46 and DC4) as realistically as possible, but I don't know what is realistic for these planes.

Thanks for any help
 
I don't have the answers to your questions, but you might take a glance at this site, the tab Technical at the top: http://dc3airways.com/
If that doesn't answer your questions, they DO have real world (where IS that place??) DC3 pilots in their forums. You might try asking there...
Pat☺
 
As said on the previous answer go to DC3 Airways which is dedicated to DC3s and DC4s. Mine of information and links. Quite a few flights there as well. Very friendly bunch. The autopilot was a Sperry. I am about to fly the Hump routes which I got from there in an old style DC-3. Started off in the US and just got to the first base. Taken me a few years to get there with other flights and real life getting in the way.
 
LOL Lots of good questions.

Yes, even during WWII most of these types had some form of autopilot (mostly variants of the Sperry systems) that would hold heading and altitude, and even maintain a climb angle which would require adjustment as weight and power changed. They were not the "set and forget" types we commonly see today.

Over the years, most were updated - either by owners' choice or to comply with changing regulations. Back in the days when all pilots were tough and heroic it was commonplace to hand-fly the aircraft (or they didn't trust the 'newfangled gizmos'). With changing technology, comfort and ease of operation became common.

A search of Buffalo cockpit photos online http://www.airliners.net/search?key...pted&sortOrder=desc&perPage=36&display=detail will show a variety of equipment including older analog radios and modern bits from Narco, Bendix, Garmin and others dropped into the panels.

Joe McBryan is very much a believer in pilots flying the aircraft so he generally wanted to see hand-flying on departure and arrival, but saw autopilots as useful during cruise. That being said, if Joe is not looking over your shoulder in the sim, you can probably get away with using the equipment if installed - and modern autopilots were. For your sim experience it largely depends on how much skill you want to develop, what era you are simulating, and how much time and attention you can pay to the actual flying.

Policies and procedures for other operators may vary. :adoration: Personally, I'm with Joe and wish more sim pilots would learn to fly and not just "twiddle the knobs". :encouragement:

Yes, old, analog aircraft can have modern autopilots and even GPS-coupled systems installed. It just depends on the size of the bank account.
 
Guitar00633 - Perhaps this may help. Older aircraft (generally pre 1970's with exceptions) had limited autopilots, the limitation is the flight axis the autopilot controls. There are three main axis, roll pitch and yaw and to make an autopilot work you need an instrument that could sense changes in these axis and apply corrective forces to the controls to make it work. Like model aircraft servos were needed to placed in the control lines to apply these forces. Early autopilots were two axis units only heading and pitch.

Lets look at the Sperry, widely used in just about everything for probably 70 years as far back as the 1930's, it consists of two gyros driven by a vacuum pump driven by the engine (hence the suction or vacuum gauge on the unit), these gyros are the sensors and via electrical servos would make adjustments to the elevators and rudder to control yaw and pitch, turn and climb or descend. Because of lag and the limited control power of the servos these units could not produce a fine level of control and could be overcome by aerodynamic forces that exceeded the power of the servos to control changes (lag). So this leads us to the solution and how these systems work.

The very basic form of autopilot and what is called a secondary control in an aircraft is actually the TRIMS, these units control the movement of the control surface, so in basic pilot training understanding the correct attitude for level flight, climbing, descending and turning is drummed into pilots from day 1 or it should have been, and then it was - trim, trim, trim. Trims control and relieve control pressures and relieve the pilot of the need to physically hold the controls in a particular way so a well trimmed aircraft would be able to literally fly stable hands off! You need to imagine how tired your arms and legs would get if you had to hold a large amount of force on a stick for 20 plus minutes, say in a climb, without any assistance. Think of it this way, every time you change the attitude of the aircraft you need to re-trim the aircraft, well designed simulator models are no different.

As aircraft became bigger and faster the amount of physical control force needed to be applied by the pilot got larger and larger (a larger and heavier aircraft or fast aircraft could required you as the pilot to be able to apply as much as 150kgs of force or more to the control to make it move under certain conditions such as pulling back out of a dive it is the same as doing weights imagine jerking and lifting 150kg and you will get the idea, as an aside this is one reason why women were once thought not to be suitable to be pilots because they could not apply these sort of physical forces) so you can imagine the amount of physical pressure you needed to apply to the stick or control column to keep the aircraft in the attitude required, hence the development and incorporation of trims which are just a small deflection or moveable surface on the control surface which moves in the opposite direction to the surface hence applying a balancing force and keeping it in that position. Early autopilots controlled and most systems still do, move the trims, not the main control surfaces. It is the reason why you will see the trim wheel moving constantly in a modern jet or similar aircraft when the autopilot is engaged, the trim surface is constantly being changed to maintain the desired attitude.

So because of the engineering problems early on the two main controls that had trims were the rudder and the elevator why because of what is known as coupling, in simple terms, a roll causes yaw and a yaw causes roll so by simply inducing yaw you could produce roll but it is not all that tidy but it works. Elevators are much more easy because of pitch its either up or down. Even today most light aircraft for example will only have two trims, rudder and elevator and very very few have aileron trim, it increases the complexity of the aircraft control design and cabling. You also need to remember that most aircraft have wire and rods connected to the cockpit controls so you are pulling and pushing on a long piece of wire or rod to move the control surface, you need a very large electrical servo to do this so it is much easier to have a smaller unit driving the trim control as it needs less torque and hence less force to achieve a change. Thing only really change when you move to hydraulic controls as all modern jets etc have because you can generate a large amount of force with a hydraulic system as compared to an electrical/mechanical system. And you also need this type of power to move an all moving stabiliser such as is now common on Boeings etc. How that works is similar but would need a whole new post to understand.


To use the era of autopilot fitted to DC-3s, DC-4s etc you need to understand that the aircraft was hand flown to the desired attitude and heading and then the autopilot would be turned on to hold that attitude and heading. Because of the inherent limits of the gyros in the unit they wander over time and from time to time it would be necessary to turn them off, hand fly the aircraft back to the required attitude and then turn it back on again. You can under reasonably stable air use the heading change to make the aircraft go to a new heading and the pitch control to pitch it up or down but I emphasise these are smooth air capacities and the era of servo controllers and vacuum driven gyros was not precise enough to provide precise control at all times, so the lesson of all this is that the AUTOPILOT was seen as an AID not as a sufficiently powerful, reliable and controllable system to provide full and all weather control. I have flown these types of aircraft and many many times have had to disconnect or turn off the autopilot because it could not control the aircraft due to turbulence etc and hand fly the aircraft and then put it back on again. Sometime it was just easier to hand fly the aircraft because in severe weather they could not cope.

The next advance on this type of system was the coupling or connection of the electrics to the signals for the navigation instruments allowing the autopilot system to now obey or follow required headings and or tracks being produced from the navigation system, but I stress in this era of the DC-3, 4 , etc, the main navigation aid was the NDB or ADF and this was not achievable because of the way these navaids work, they work on the AM band (not VHF or UHF) with low power and have significant problems from interference etc etc, the VOR and the ILS was different but to get the autopilot unit to a stage where it could apply control inputs based on the data from these receivers took a lot of electronics and they were simply not around then, this all changed when navaids and the aircraft systems moved from vacuum tubes and hand made components to becoming electronic, solid state, then digital.

As to why these aircraft were not retrofitted the answer is also simple, that would mean fitting a completely different control system, electrical services etc etc to make it happen and it is just not feasible given the build of the aircraft, control runs, electrical systems etc etc. As the previous poster said, achievable but you needed a very big bank account and incredible fortitude and stamina to put up with the regulators who would triple the cost with their demands for certification, safety cases, etc etc. No much easier to back to first principles, fly the bloody thing and use the trims!

I hope this explains some of your questions.
 
guitar0633 - Feel free to ask me any more questions you like and I will be happy to answer them if I can. Have flown the DC-3 but not the DC-4 or the C-46 they were all out of service in Australia well before I finished high school. I am an ex military QFI and C&T Captain and have over 6000 hours in piston engined aeroplanes. I guess I was condemned for my sins to be what was jokingly referred to in OZ as a 'boat driver' because they had propellers, LOL. I have been flight simming since MS98 arrived and find it a really great interest and hobby particularly if your interested in historical aircraft you would be surprised how many current flyers use flightsim to help keep their skills up particularly what is called IFR procedural flying. We used MS Flight Sim as a desk top aid for trainee pilots on pilot course to help them practise a lot of IF stuff as real Sim time was precious and they could have a go at a flight before doing it for real.

Piston engined aircraft are actually daunting to the unitiated because the big birds need a lot of care and attention in the engine department that being said they were generally pretty reliable and a lot more robust than people think.

The key to piloting them and any aeroplane is the golden rule ATTITUDE+POWER = PERFORMANCE. So another tip for these aircraft is to remember that you need to remember what attitude and what power gives what performance. Take Offs and Descents are generally the only real tricky area because you have on take off and engine running at maximum power and on descent you needed to look after them to avoid shock cooling the finned pistons on descent, the general rule was 1"of MP reduction per thousand foot on descent so you need to think about it in advance, how much to lose how far to go. The other thing to remember these birds were not spectacular climbers generally between 500 ft and 1500 ft climb depending on how heavy you were and descents were always planned at 500 ft per min standard rate of descent, so there was no need to rush down and no need to pull back the power levers. In a turbine by comparison you can fly a profile descent and keep the speed right up to the barber pole all the way until going through 10,000 ft when you needed to get the spoilers out and a level off segment to get the speed back for your approach profile. I have done it in the old props, crews used to call it the 'space shuttle descent' but you needed to really know how to moly coddle the engines.

Cheers
 
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