Level D Flight Simulators
 

Good Afternoon All, I've searched for information on Flight Simulators but
I'm falling short.

Are there any members on this site that work with/maintain full flight simulators?

I'd like to direct a few questions to those familiar with the technical side
of the sims if possible.

Thanks!

Pretty sure alot of people on here work with those sims. What are your questions?

I have few questions, but I'll start with the background first:

My understanding of a flight simulator is that it's an exact replica of it's
real-world counterpart in the sense that all instrumentation, seating,
layout, etc. are authentic.

Is it safe to say that the CDU's, altimeter gauges, and all other devices
are in fact those purchased from avionics companies as used in the real jets?

The next question gets tougher! :D

Yes the equipment is the same. Judging by your handle of "Learningtofly" you are a low time pilot. These sims are typically owned by airlines and replicate newer models of jets. My airline has a level D A-320 sim for example. It has both night and day visual. If you make a firm landing it will let you know!!

I know you can pull some of the instruments and stuff out of the sim and use them in the airplane, same part number.

Yes, in fact most CAE made simulators are modeled after an exact serial number aircraft that may still be flying. For instance our Beechjets simulators are modeled after serial number 249, which still operates for a lawfirm in Florida. It has the exact same equipment list as the real airplane down to every switch and dial. Everything from the pilots viewpoint looks exactly as it would in the airplane, and I'd imagine many of the components are precisely the same ones found in the real aircraft. However, a few probably have been modified in order to work in the simulated world versus the real world environment.

I don't have much a technical background in simulators, but I have over 500 hours of acting as a fill-in captain or co-pilot for Level-C & D training sessions.

Thank you for the replies everyone. You're correct when you say I'm not likely to step into a class D sim. anytime soon; this is fascination and
interest more than anything...not to mention I'm a tech. geek!

I know these simulators use powerful computers to handle the motion
platform, animated displays, and instrument functions as well as the
training scenarios.

From what I've read, there are interface cards for computers which communicate
on the data bus using the ARINC protocol. If I'm not mistaken, the
entire instrument set outputs on the same bus for data capture.

Now the tricky quesitons:

Is every known input to the cockpit displays and Flight Management
Computer (FMC) emulated, or do certain measurements get omitted?

For instance, Angle of Attack is normally handled by air flowing over
the AoA sensor. Is this sensor programmed with respect to the angle
of the hydraulic platform, or does the computer calculate AoA based
on empirical data?

Likewise for Pressure altitude, and air speed, etc.: Does the pitot-static
system exist on the flight sim.? Is there some sort of pneumatic device manipulating the pressure in the static port and pitot tube, or does the
simulator software produce the altitude on the guage(s) using digital to
analog conversion?

A couple of thoughts and questions for you first. First I am not a simulator engineer, just the general aeronautical engineering kind and there may not be any advanced simulator designers or simulator technical workers using these forums. Since it is a pilot forum, we may have a few sim operators (probably do). These days the engineering is pretty complicated. In addition, there is a proprietary aspect in play that impedes the dissemination of design details in order to save them for the paying customer at Flight Safety, SIMCOM, Higher Power, an airline, or NASA to name a few.

But the fundamentals of flight simulation is part of the curriculum for any approved aeronautical engineering degree, and in my own coursework I have designed some of the more basic simulators as a part of the program. Have you had courses on flight dynamics, aerodynamics, systems, or handling qualities? How about electric engineering, control theory, human factors, or flight psychology? And are you a certificated pilot of some kind? If you have any of these in your background my answer will be different. The answers to many of your questions can be found in college engineering courses, specifically the study of flight dynamics. The latter serves as the entry point for all flight simulator design. All flight simulators have in common some type of mathematical model of flight which serves as the core of the system. Once this is chosen, control theory and systems dynamics can be applied. This seems to be your area of interest.

Thanks Cubdriver. My current field is actually aerospace technology
working with RF communications. I have some background in programming, process automation (PLC) and circuit design to name a few.

My interest is primarily 'how' all of the systems are emulated to reproduce
certain measurements and produce an interactive display. Ultimately I'm
wondering how far back the electronics are peeled away from their jet
counterpart.

Altitude for instance could be simulated by a computer data steam that
connects directly to the altimeter hardware driver...or it may be more
complete and run through the Flight Management Computer via the
static port transducer.

In any case, I'm not looking to pull any proprietary information from the
MFG; I thought this might be general knowledge.

My last question pertains to flight data and how it can be used to
recreate a flight scenario and/or train a user. I read about the
Airbus landing in the Hudson river and how investigators used the
data from the Flight Data Recorder to playback the entire flight in the
simulator.

Apparently, the yoke and thrust are automated (along with other
controls)? Investigators could actually watch the controls move
just as the pilots would have operated the aircraft in their emergency
landing?

This is what sparked my initial post; I didn't realize the real world
jet could produce flight data that could interact synonymously with
a flight sim. It's amazing how detailed and accurate the sims. really are!

Ok, you are not an engineer although you probably think like one, so I will treat your inquiry that way. You do have a programming background which is useful in flight sim design. Various languages are used to make flight sim engines such as Java, C++ and their variants. This will give you a lot of insight into how the actual computer implementation of a flight model can be done. However not having taken engineering theory (see above list) you are going to have to do some (serious) howework if you want to understand it. Engineering deals with applying science to making useful things. Science tell us how we can make a flight model. Flight sims all have at the core some sort of physics model of some stripe, whether they depend on data tables, blade element theory, quaternions, Eulerian equations, or fuller aerodynamic and flight-dynamics equations permitted by modern industrial computers. On the home user level, you can download a free flight model such as:

6-DOF FLIGHT model

To operate this model you will need a version of MATLAB, and I am afraid it costs money. I think I paid $100 for mine. You will also want a basic desktop sim-setup like a joystick, rudder pedals, and a throttle quadrant. If you are a home simmer you already have these. Bear in mind you are not getting any of the exciting visuals and aircraft using MATLAB, but you will be able to gain access to many useful things not the least of which is the data output you want to understand how cockpit sim instruments work.


You are going to have to get more specific to understand the answer to this. Obviously, in a desktop sim there are no measurements beyond the pilot control inputs. In a Level D sim there are millions of dollars worth of actual working controls, the same ones used on the real aircraft in most cases. The difference is they do not go to the real systems, they interface through potentiometers and DAC units (digital to analog converters) to deliver digital information that can be used by the flight model. Conversely, when the data comes out of the computer it is digital data that has to be converted to analog a similar process, namely through the use of transducers. Nowadays you have all glass cockpit aircraft with no moving parts beyond an air data computer, so there is an almost total lack of these items and the only physical interface left involves the flight controls. Simulation quality has improved a lot because the calibration of physical instruments is no longer a factor.

There are no static ports and the ambient atmosphere is irrelevant in a flight simulator. Same for all the other pitot-static instruments. There are however various feedback accelerometers on the simulator telling the computer where it is as it moves through 6 degrees of freedom on the Stewart Platform.

I can't help you here because I do not know mush about the sophisticated FDRs used on airliners these days. I believe they record the last 30 minutes of relevant data streams taken from the flight computer, whether the fly-by-wire system used on Airbus or the computer that is used on the mixed systems. There literally could be a hundred parameters going into the FDR. Aircraft configuration, cockpit sounds, digital atmosphere measurements, possibly even some ACARS data could be in there. No doubt it is everything a crash investigator would want to know to set up a replay or analyze a crash.

Speaking over my head a bit here... but yes, I believe so. Flight automation has been around for many years, so it is no wonder that a 50 million dollar flight simulator can fly itself for the most part.

I agree, and this is a fascinating subject. When you get to 20 posts you can PM and I will give you some contacts who work with Level- D sims. You may want to buy a book or two like these, also.

Flight Simulation- Rolfe
Flight Simulation- Lee