speedracer1407
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Full Motion Simulators

Wed Apr 19, 2006 7:01 pm

Hey folks,

It's my understanding that full motion flight sims, the expensive ones used for heavy metal training, provide a unique experience that replicates the actual flying experience far better than non-moving sims.

I realize that no simulator can replicate actual flying, but I wonder just how close they can come.

Not that I would know, since i've never flown anything, but it seems to me like one of the most alarming things about flying a big jet (or any plane, really) in an unusual attitude situation might be the sudden and/or sustained high G-forces that might make flying and instrument monitoring difficult. Even if a full motion sim provided 20 feet of vertical motion, it seems as though it would be impossible for it to replicate anything other than basic bumps associated with moderate turbulence.

So my question is how effective are full motion simulators at actaully replicating unusual motions? Is their primary purpose to simply replicate vision-bluring turbulence, acceleration, and deceleration? Do they manage, despite my uninformed skepticism, to actually simulate crtical G-forces? Does anyone here want to send me a lot of money to experience it for myself?

O
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Starlionblue
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RE: Full Motion Simulators

Wed Apr 19, 2006 8:28 pm

Having spent a few hours in a 767 sim and a Bell 206/406 sim, I can tell you that it is much closer to reality than you think. The motion is incredibly lifelike and indistinguishable from the real thing. The 767 I tried was built in the 80s, so the graphics (out the window) were a bit blocky, but in newer sims that aspect is much improved.

Still, turbulence and G-forces are very very realistic. Of course, if you want to roll it won't move all the way around that, but you will get most of it.

As for "can't replicate actual flying", I would say this is hardly true anymore. Wing told us a few months back of how F/Os would not get any training in the actual plane before flying a revenue flight. Sims are that good.
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pilotaydin
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RE: Full Motion Simulators

Wed Apr 19, 2006 9:35 pm

I just spent 60 hours in the 737-400 full motion sim and got my type rating, when we did unusual attitudes and stalls, trust me, it's pretty real lol, the sounds, the noises, the smoke and the o2 masks...everything feels damn real, ESP at night time,

we crashed once during training, both of us covered our faces, my sim partner and i, and we had to hold on because it was rocking around violently... so it's pretty realistic.
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Pihero
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RE: Full Motion Simulators

Wed Apr 19, 2006 9:38 pm

What a simulator does is cheating on your senses.
There is no gyroscope in a human cranium, just a balance and movement sensor given by a few hairs inside a minuscule oil box : the oil movement acts on the hairs which in turn convert it into sensation. Hardly precision instrument. But it is enough for a ground dweller. For pilots, it has to be implemented with instrument training.
That said,this is a simple way to describe a simulator cab movement:
-Suppose you are flying straight and level at a low speed. Then you want to accelerate to Vmo ;you push the throttles forward ...on a real plane, you are pushed into your back rest, right ?The sim cab moves forward just a bit and at the same time, the cab is pitched up,thus replacing your horizontal acceleration with earth's gravity. Result, you're pushed into your back cushion, but as you're still watching a screen that moves with you, you don't notice the pitch increase... When the acceleration stops, the cabin very gently returns to its reference position, again in a manner that's not detectable by your inner ear.
-Now suppose, you're landing on a short field and want to maximize your braking,the cab pitches down and you're hanging by your shoulder belts.

Watching a simulator cab move, from the outside is rather impressive ; one has the feeling that a bunch of mad monkeys have taken over the training ! but in reality, the piloting is very smooth and supple . It just gives you an idea of the micro-accelerations present in every flight.
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wing
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RE: Full Motion Simulators

Wed Apr 19, 2006 10:03 pm

Quoting Speedracer1407 (Thread starter):
So my question is how effective are full motion simulators at actaully replicating unusual motions? Is their primary purpose to simply replicate vision-bluring turbulence, acceleration, and deceleration? Do they manage, despite my uninformed skepticism, to actually simulate crtical G-forces?

I think there are different angles to look to this question.Yes nowadays a Level D simulator is considered enough for the 3 landings and take offs on the actual airplane.
But at nopoint of the trainings there actually a need to create the turbulance or the g feelings.Maybe because I feel like "its just a simulator" I didn't have any significant feeling of any critical g-forces.

Simulators are more like the "procedure training" environments with a realistic sights and sounds.You can not train the pilot for the turbulance or g-forces in the simulator.

To cut the long story short when I get out of the simulator what remains in my mind is what I do in an engine fire,who does what under which role(PF-PNF) etc,not the graphics or the capabilities of the sim.
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YYZatcboy
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RE: Full Motion Simulators

Wed Apr 19, 2006 11:18 pm

I work on a 30 seat motion simulator at Ontario Place here in YYZ, and while it is not a Flight deck, it sure does give you a sense of G forces, and looks crazy when moving, especially from underneath.
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SNA350
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RE: Full Motion Simulators

Wed Apr 19, 2006 11:49 pm

a simulator is véry realistic

the visual system takes care of 80% of simulation
the rest is done by the motion system

when performing a take off in a simulator the G forces are very realistic
also the bump on landing is simulated very good

the only thing a sim can't simulate is the lower pressure in the cabin when flying high
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CX Flyboy
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RE: Full Motion Simulators

Thu Apr 20, 2006 2:12 am

What Wing says is correct, however in my years of flying these sims, I have only once or twice forgotten that I am in a sim. The sim I use does not replicate the randomness of turbulence very well, and the noise of the hydraulics can actually penetrate the inside of the sim at times. The graphics are not as good as FS2004, as the sim is pretty old as far as 777 sims go, and the noise package could do with an upgrade.

...having said that, it is still fairly realistic for most manouvres, and although any violent manouvres do not feel very real, as Wing says after a sim session I am thinking about my performance during the various manouvres and not the realism of the sim.
 
bri2k1
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RE: Full Motion Simulators

Thu Apr 20, 2006 8:24 am

Quoting SNA350 (Reply 6):
the only thing a sim can't simulate is the lower pressure in the cabin when flying high

I just read in Flying magazine where FlightSafety has a way to simulate high-altitude conditions using a mask with a lower partial pressure of oxygen during simulator sessions.

I can say from personal experience that turbulence is real enough in the sims. I used to date a girl whose mom was a CFI and dad was an electrical engineer who both worked at the UA training center in Denver. I got to fly every plane in the fleet, and this was before I had my PPL. Sometimes, they'd throw me into weather systems in a 777 so bad that the CFI would get "airsick" and have to stop the motion and get off.
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Starlionblue
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RE: Full Motion Simulators

Thu Apr 20, 2006 9:06 am

Quoting Pihero (Reply 3):
There is no gyroscope in a human cranium, just a balance and movement sensor given by a few hairs inside a minuscule oil box : the oil movement acts on the hairs which in turn convert it into sensation. Hardly precision instrument. But it is enough for a ground dweller. For pilots, it has to be implemented with instrument training.
That said,this is a simple way to describe a simulator cab movement:
-Suppose you are flying straight and level at a low speed. Then you want to accelerate to Vmo ;you push the throttles forward ...on a real plane, you are pushed into your back rest, right ?The sim cab moves forward just a bit and at the same time, the cab is pitched up,thus replacing your horizontal acceleration with earth's gravity. Result, you're pushed into your back cushion, but as you're still watching a screen that moves with you, you don't notice the pitch increase... When the acceleration stops, the cabin very gently returns to its reference position, again in a manner that's not detectable by your inner ear.

Even Einstein knew this. That is, it has been clear to physicists for some time that a force is a force is force. If you produce a force through acceleration by the engines (in a real plane) or through gravity (in a sim) there is NO WAY for your brain to tell the difference. Because there is no difference force wise.

Quoting SNA350 (Reply 6):
also the bump on landing is simulated very good

Try riding over the runway lights. Bump. Bump. Bump.  Wink



I did see an antique F28 sim once. That would not have suspended my disbelief...
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SlamClick
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RE: Full Motion Simulators

Thu Apr 20, 2006 9:07 am

I can remember several occasions when I spent my two hours in the simulator practicing approaches at LAX and the 'weather' was low overcast, rain, generally crummy. At the end of the evening we climbed out to go back to the hotel and we actually were in Los Angeles but I was surprised to see that the weather was really nice. I'd gotten completely into the environment the sim had created.

The way Pihero and others describe it is spot-on. It does a very good job of tricking you.

Doing rudder crossover demos in the sim, we'd have a student roll 120 degrees and pull the nose 30 degrees below the horizon then freeze it for a quick briefing. If we'd give them the visual at that moment most would find it very uncomfortable.
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Starlionblue
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RE: Full Motion Simulators

Thu Apr 20, 2006 9:18 am

Quoting SlamClick (Reply 10):
Doing rudder crossover demos in the sim, we'd have a student roll 120 degrees and pull the nose 30 degrees below the horizon then freeze it for a quick briefing. If we'd give them the visual at that moment most would find it very uncomfortable.

Yes well trying to land the helo on the roof of a hospital and tipping off the edge was no fun either. Big grin
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SNA350
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RE: Full Motion Simulators

Thu Apr 20, 2006 11:32 pm

Quoting Starlionblue (Reply 9):
Try riding over the runway lights. Bump. Bump. Bump.

or landing so hard that you get a flat tyre  Wow!
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IFEMaster
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RE: Full Motion Simulators

Fri Apr 21, 2006 5:47 am

I've never been in a sim.

All of the stories above make me insanely jealous.

Which one of you can I pay to let me have a go in a really good sim?  biggrin 
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Starlionblue
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RE: Full Motion Simulators

Sat Apr 22, 2006 1:32 am

Quoting IFEMaster (Reply 13):
I've never been in a sim.

All of the stories above make me insanely jealous.

Which one of you can I pay to let me have a go in a really good sim?

There are several sim facilities that allow unaltered humans to fork up the money and fly for a few hours.
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IFEMaster
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RE: Full Motion Simulators

Sat Apr 22, 2006 5:31 am

Quoting Starlionblue (Reply 14):
There are several sim facilities that allow unaltered humans to fork up the money and fly for a few hours.

There are????

Don't suppose you have any details, do you?
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pilotaydin
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RE: Full Motion Simulators

Sat Apr 22, 2006 7:28 am

you can fly on lufthansa sims if you have enough miles...unless they cancelled that...it was something like 75,000 or 90,000 miles for an hour on the A320
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JayinKitsap
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RE: Full Motion Simulators

Sat Apr 22, 2006 8:04 am

Boeing used to give 1 hour 747 simulator session for 4 persons to charity groups to auction off. This is back like 12 years ago and I don't know if they still do. At a auction at my son's private school it went for like $1,800. A few months later we were at a church school auction which was lightly attended. One of the last items was the simulator session. Everybody was tapped out so I won it for $350. My two sons, my wife, and I spent the hour there about 8 at night. We selected BFI at night, could see the headlights going by on I-5 with the cars moving different speeds. Each of us got 15 minutes which was a take off, cruise around then the guide reset to align the plane on the landing flight path. (He said it was pretty tough to get aligned properly unless a trained pilot) We then took it in for the landing.

I was a pretty normal flight, when my wife was flying I asked the guide what could they simulate, he replied "Oh engine fires" as he started the #2 engine on fire, my wife panics with all of the alarms as she looks back she pulled back and stalled the plane - very exciting. The guide froze it before it crashed. He said it takes a very long time to reset after a crash. Later as she landed she got the rudder pedals backwards so we are suddenly crossing the grass, very realistic feel, before she turned down the taxiway.

When my older son was flying it he asked if he could do a barrel roll, the guide said sure, got him climbing slightly and indicated to do it fairly quickly. We rolled over about 30 degrees where the simulator hit the stops and the screen kept turning. Once the simulator could be at the other stops - wham - we flipped thru 60 degrees to the far side, where the simulator continued the roll.

As we finished up the guide indicated that to be certified the simulator's response and feel (yoke pull etc) must be within like 1% of an actual plane.

Sims are an incredible training tool, able to replace a good part of real time training and allow to train for responses to problems difficult or hazardous to replicate in real life.
 
bri2k1
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RE: Full Motion Simulators

Sat Apr 22, 2006 9:31 am

Quoting JayinKitsap (Reply 17):
He said it takes a very long time to reset after a crash.

I never crashed one, but the first time I flew the A320, another engineer who designs and maintains the sims decided to try a complete roll. We reached the bank limit of the motion, which must have been at least 60 degrees. At that point, the motion stopped, and the video disappeared. The sounds and instruments, though, continued to respond correctly, and he finished the roll. We could have kept on flying, but it wasn't fun wtihout motion or video, so I got to tour the computer room while he reset it. It took something like 90 minutes to reboot everything and get it back online!

Quoting Starlionblue (Reply 9):
Quoting SNA350 (Reply 6):
also the bump on landing is simulated very good

Try riding over the runway lights. Bump. Bump. Bump.

The one that got me was the runway cracks. The first time I ever flew one, it was the 777 out of DEN, at twilight. They started me on a taxiway, so I got to play with the tiller a bit, and when I was lined up on the runway, I did marvel at the headlights of the cars driving on the road beside the airport. As I moved the throttle to the T/O power detent and sank into my seat from the "acceleration," I saw a fairly large crack, maybe it was an expansion joint or a water channel, across the runway. As I rolled over it, there was a "ba-BUMP" sound, and the sim dipped just as if we'd rolled over it with the nosewheel. At that point, I got really scared, because I realized we were about to take off, and I had no idea how to actually get us back on the ground! It is very, very realistic, and I've made that statement before and after I became a pilot in the real world.

Quoting IFEMaster (Reply 15):
Don't suppose you have any details, do you?

In those days, about 6 years ago, and pre-9/11, they told me they rent the sims to other airlines for instruction at around $1000 an hour. Sevreal of the instructors belong to the same flying club I do, and if you actually have that kind of spendable cash, 1.) I want to become your friend and 2.) I can put you in contact with someone.
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MidnightMike
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RE: Full Motion Simulators

Sat Apr 22, 2006 10:56 am

Full Flight Simulators are quite amazing as they replicate the feel of the aircraft.....

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LHSebi
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RE: Full Motion Simulators

Sat Apr 22, 2006 1:14 pm

Quoting IFEMaster (Reply 15):
There are????

Don't suppose you have any details, do you?

www.proflight.de

There you can book any of the LH sims in Frankfurt, Bremen, or München. The "sessions" you can book online are not an hour in the sim. You have to share the hour with 2 others, giving you only 20 mins of flying, which is really nothing. You can call them, and arrange the sim for an hour for yourself and 2 people of your choosing. You get a LH pilot that comes with you, and its great fun. When its just you and your friends, the pilot will usually let you do a lot more (from my experience)  Smile.

Enjoy!
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jspitfire
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RE: Full Motion Simulators

Sun Apr 23, 2006 10:08 am

I've been doing training in a King Air A90 Full-motion simulator, and it is very realistic. The simulator does not have visual, but it doesn't make that much of a difference, considering it's all IFR training.

My mind gets very confused when we're doing a steep turn, and I look out the back of the sim, and see that the sim is completely level. So yes, full motion simulators do a very good job of simulating the real thing.

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Grbld
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RE: Full Motion Simulators

Sun Apr 23, 2006 10:17 pm

Lot's of talk about the G-forces in a sim and that's actually where it can't simulate everything. Sure, it will sit on its back during takeoff and on the nose during deceleration, but it won't simulate the 2G in a level 60 degree bank turn. (or 1.7G in a 45 degree bank) There simply is no way, because for all other G-simulations, it uses the only G-force available: Gravity. So there's NO way to simulate sustained G-forces more than 1g. Or less than 1g, for that matter.

Quoting Jspitfire (Reply 21):
The simulator does not have visual, but it doesn't make that much of a difference, considering it's all IFR training.

Actually, it makes a LOT of difference. On a modern simulator with 160+ degree wrap-around vision, you'll even FEEL that you're moving when the hydraulic motion system is turned off!! Usually, the first few sessions of a type rating are done fixed base, so only visuals and no motion, in order for the unfamiliar crew to just get acquainted with the aircraft. And still it "feels" like you're moving — that's how much your eyes play a part in deceiving you! Of course, this applies when there's actually a horizon displayed. Even on relatively early projected displays where the ground is just green, the sky is blue and there's a rudimentary runway in front of you, it still has the same effect. There, you also see how programmed your eyes and brain are to associate the color green with ground and blue with sky.

Sims are very interesting, physiologically  Smile
 
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Starlionblue
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RE: Full Motion Simulators

Sun Apr 23, 2006 10:44 pm

Quoting JayinKitsap (Reply 17):
As we finished up the guide indicated that to be certified the simulator's response and feel (yoke pull etc) must be within like 1% of an actual plane.

Indeed, which is why they are so expensive. CH Products makes joysticks. One of the applications is games. Some cost about $200. But the equivalent professional joysticks, like the ones they make for the Shuttle sim, cost 10x as much at least. It's all in higher spec.

Quoting Grbld (Reply 22):
So there's NO way to simulate sustained G-forces more than 1g. Or less than 1g, for that matter

Sure you can, if only for brief periods. By driving the box forward at more than 1g. Your body doesn't know the difference.

NASA has (had?) a shuttle sim that went up and down like an elevator in a big shaft.
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SlamClick
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RE: Full Motion Simulators

Sun Apr 23, 2006 11:56 pm

Quoting Jspitfire (Reply 21):
My mind gets very confused when we're doing a steep turn, and I look out the back of the sim, and see that the sim is completely level. So yes, full motion simulators do a very good job of simulating the real thing.

I don't understand what you could be looking at that would be level. In the full-motion sims I'm used to (see the pictures above) the entire cab is on the hydraulics and the instructor and his station maneuver with the students on the 'flight deck.' How could it be 'full motion' and simultaneously 'completely level?'
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CosmicCruiser
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RE: Full Motion Simulators

Mon Apr 24, 2006 12:11 am

Quoting SlamClick (Reply 24):
How could it be 'full motion' and simultaneously 'completely level?'

Hey SlamClick, I was thinking the same thing but decided not to "muddy the water".LOL In all the full motion sims I've been in once the motion is on the doors must be closed, the ramp pulls away and you can't see out the back .CC
 
MidnightMike
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RE: Full Motion Simulators

Mon Apr 24, 2006 12:34 am

Quoting Grbld (Reply 22):
Lot's of talk about the G-forces in a sim and that's actually where it can't simulate everything. Sure, it will sit on its back during takeoff and on the nose during deceleration, but it won't simulate the 2G in a level 60 degree bank turn. (or 1.7G in a 45 degree bank) There simply is no way, because for all other G-simulations, it uses the only G-force available: Gravity. So there's NO way to simulate sustained G-forces more than 1g. Or less than 1g, for that matter.

Much of what goes on in the Full Motion Simulator is visual, when in the simulator close your eyes, & the sensation of the motion lessens. The simulator is meant to tricks your senses....
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SNBru
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RE: Full Motion Simulators

Mon Apr 24, 2006 12:54 am

Quoting Grbld (Reply 22):
There simply is no way, because for all other G-simulations, it uses the only G-force available: Gravity. So there's NO way to simulate sustained G-forces more than 1g. Or less than 1g, for that matter.

Actually that is not completely true. I graduated on the motion feedback on full motion flight simulators. Except for the tilting of the simulator cab, the simulator also will simulate the high frequency movements through accelerating the actuators (sometimes with more than 1g, but only for a limited amount of time). The human vestibular system is only sensitive to accelerations, so no displacements are simulated but accelerations. High frequency filters will simulate only the beginning of a maneuver (bank angle) but will later on slowly move into a neutral angle. This maneuver won't be noticed by most pilots. So actually it is more complex than just using the gravity for simulating long accelerations.

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bri2k1
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RE: Full Motion Simulators

Mon Apr 24, 2006 2:40 am

Quoting SlamClick (Reply 24):
I don't understand what you could be looking at that would be level. In the full-motion sims I'm used to (see the pictures above) the entire cab is on the hydraulics and the instructor and his station maneuver with the students on the 'flight deck.' How could it be 'full motion' and simultaneously 'completely level?'

I'll take a guess. Once any turn is established and coordinated, you should pretty much feel "gravity" pulling straight down. One way I can see if I'm making a coordinated turn (in a real plane) is to see if there's equal pressure on both butt cheeks. It pretty much matches exactly what I see in the turn coordinator. I bet the same is true for the simulator, but I didn't know enough about piloting when I flew sims to know for sure. Most of the sims have doors with no windows in back, but there could be one with a window, or they could have left the door open.

The body is sensitive, but not overly sensitive. When I was doing initial training, an instructor had me put on the hood, fly straight and level on instruments, then close my eyes and put my head down in my lap, and keep flying straight and level. I could hear climbs and descents by subtle RPM changes, so I kept altitude. But, in about 2 minutes, I did a complete 180-degree turn to the left. I bet the simulator can take advantage of our lack of sensitivity to roll us into the turn with a steep bank, then very gradually (undetectably) return to level in case we command more bank angle in the same direction, it will have more travel to give to simulate another increase in bank. It's just a guess, supported only by my personal obeservations.
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zeke
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RE: Full Motion Simulators

Mon Apr 24, 2006 3:34 am

Quoting Speedracer1407 (Thread starter):
So my question is how effective are full motion simulators at actaully replicating unusual motions?

Replicating real unusual attitudes in full motion simulators are not done very well. The simulators are built on aerodynamic models which are refined from actual flight test data, they are good at replicating normal situation, or abnormal situations like a flap failure, engine etc out as these can be testing in an aircraft.

True unusual atitudes are not tested in real aircraft, so we done have a finite model to base the simulator on.

That being said, the teching of unusual attitude recovery can be taught and practised in simulators as the instructor can position freeze, or reposition the student in some very unusual situations.

Quoting Speedracer1407 (Thread starter):
Is their primary purpose to simply replicate vision-bluring turbulence, acceleration, and deceleration? Do they manage, despite my uninformed skepticism, to actually simulate crtical G-forces?

They cannot simulate critical G forces which would be experienced in unusual attitudes, the can simulate takeoff acceleration and deceleration, climbs, descents, and yaw in normal phases of flight.

Quoting Speedracer1407 (Thread starter):
Does anyone here want to send me a lot of money to experience it for myself?

They are not that expensive, a number of places about will let you have a "fun hour" in one.
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Starlionblue
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RE: Full Motion Simulators

Mon Apr 24, 2006 3:58 am

Quoting Zeke (Reply 29):
Quoting Speedracer1407 (Thread starter):
Is their primary purpose to simply replicate vision-bluring turbulence, acceleration, and deceleration? Do they manage, despite my uninformed skepticism, to actually simulate crtical G-forces?

They cannot simulate critical G forces which would be experienced in unusual attitudes, the can simulate takeoff acceleration and deceleration, climbs, descents, and yaw in normal phases of flight.

While this kind of simulator can theoretically be built, it's just not worth it. I saw a docu on the Typhoon, and the sim cockpit was sitting on a pedestal in a dome shaped room. The environment was projected on the dome and the "plane" didn't move. Fighter sims do need to simulate "unusual attitudes" quite a bit but the solution in some cases is not to simulate movement at all apart from visually.

Quoting Zeke (Reply 29):
Quoting Speedracer1407 (Thread starter):
Does anyone here want to send me a lot of money to experience it for myself?

They are not that expensive, a number of places about will let you have a "fun hour" in one.

My tip: be prepared. If you only get an hour or two you want to make the most of it. FS2004, imperfect as it is, does a decent job of instrument familiarization. Also, study pics and get at least an idea of the general layout.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
jspitfire
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RE: Full Motion Simulators

Mon Apr 24, 2006 5:11 am

Quoting SlamClick (Reply 24):
How could it be 'full motion' and simultaneously 'completely level?'

When you start a turn, the sim reacts, and tilts in that direction. But as you continue that turn, it slowly moves back to level. In a coordinated turn, you shouldn't feel like your leaning over, as bri2k1 said, you should feel the same pressure on your butt, just as if you were level. When you roll out of the turn, the sim tilts in the other direction to make it feel like you are leveling out, then slowly moves back to level again.

So lets say we are turning to the left. The sim will initially roll left, then slowly level out as we continue the turn. When we roll out of the turn, the sim will roll to the right, and then slowly level out again.

The sim I have been using is from the 60's, and it does not have a door on the back, so you can see what position the sim is in relation to the platform.

Jason
 
MissedApproach
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RE: Full Motion Simulators

Mon Apr 24, 2006 6:09 am

Here's an excellent Discovery Channel clip from the CAE website
Daily Planet Video (20 Megs).
They actually employ a test pilot to ensure each simulator accurately mimics the real plane before delivery.
Can you hear me now?
 
bri2k1
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RE: Full Motion Simulators

Mon Apr 24, 2006 6:14 am

In the US, the FAA re-inspects them annually, making sure not only the motion, visuals, and sounds are accurate enough, but that the control forces in all flight regimes, switch indications, and other physical limits are adhered to, also.
Position and hold
 
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Starlionblue
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RE: Full Motion Simulators

Mon Apr 24, 2006 6:18 am

Quoting MissedApproach (Reply 32):
They actually employ a test pilot to ensure each simulator accurately mimics the real plane before delivery.

Dream job for some non-pilot aviation buffs here would be sim tech. I have met one. He works for a sim facility and performs daily maintenance on the simulators. Part of his job is ensuring they work properly after any maintenance. He's pretty good at flying  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SlamClick
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RE: Full Motion Simulators

Mon Apr 24, 2006 6:29 am

Quoting Jspitfire (Reply 31):
it does not have a door on the back

Well, there is the piece of information I needed.
Happiness is not seeing another trite Ste. Maarten photo all week long.
 
Grbld
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RE: Full Motion Simulators

Mon Apr 24, 2006 7:18 pm

Quoting SNBru (Reply 27):
Actually that is not completely true. I graduated on the motion feedback on full motion flight simulators. Except for the tilting of the simulator cab, the simulator also will simulate the high frequency movements through accelerating the actuators (sometimes with more than 1g, but only for a limited amount of time). The human vestibular system is only sensitive to accelerations, so no displacements are simulated but accelerations. High frequency filters will simulate only the beginning of a maneuver (bank angle) but will later on slowly move into a neutral angle. This maneuver won't be noticed by most pilots. So actually it is more complex than just using the gravity for simulating long accelerations.

Hi SNBru, thanks for the response. Actually, it is true, [legal mode on] as I was talking about sustained g-forces [/legal mode off]. Hold on, lemme just get Starlionblue's response in here as well:

Quoting Starlionblue (Reply 23):
Sure you can, if only for brief periods. By driving the box forward at more than 1g. Your body doesn't know the difference.

I'm talking about g-forces straight down (or up) with regards to your seat plane, like in a turn, like Bri2k1 said. It is physically NOT possible to simulate this in a stationary simulator (and by stationary I mean where the hydraulic arms are bolted to the floor of the building).

SNBru, while your vestibular system senses acceleration in 3 dimensions, the g-forces you feel in a turn, you feel on your body and your joints. Do a 60-degree bank turn in any plane, whether a Cessna or a Boeing and you'll feel the g-forces pushing every part of your body down, most noticeably your arms with which you're holding the yoke and throttle/thrust levers. As any pilot will know, these g-forces are just the thing that make steep turns difficult. Now whether you NEED that kind of thing on a Boeing or Airbus simulator is a whole different story, but my point is that it's not possible to simulate it on a normal Level D sim.

In order to simulate a 2-g downward acceleration, you need to be able to add 1 extra g downwards. To simulate this for one second, you'd need approximately 10 meters vertical movement. As you can see, since the box may be able to move upward for about 2 meters from its average position in flight, you'd not be able to get a 2-g acceleration for more than a fraction of a second. The same is true if you'd try a 0-g maneuver. So the limit for a one-second sustained acceleration would be somewhere around 1.2 g's. Woohoo rollercoaster! Especially in the 737 with its crap autopilot, I get more g's than that about every flight.

Brings me to acceleration/deceleration along the longitudinal axis: Especially during takeoff, "real" acceleration feeling is not really possible either. When you start the takeoff roll, the sim will tilt backwards but slowly will level out during acceleration, in order to be able to simulate the rotation movement. If you pay attention to this, you'll notice it. Not that it is of any great consequence, because you're probably thinking "which engine is gonna blow up? will it be before V1 or after?"

Your body helps the sim a great deal in fooling you, but it's always good to keep it in perspective: There are things that the sim can't simulate. As I'm sure anyone doing a type rating has done, play around with unusual attitudes to really test the sim. Do a loop and you'll actually feel the sim hitting the aft stops of movement, it's all baloney from there on throughout the maneuver.

Grbld
 
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Starlionblue
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RE: Full Motion Simulators

Mon Apr 24, 2006 10:25 pm

Quoting Grbld (Reply 36):
I'm talking about g-forces straight down (or up) with regards to your seat plane, like in a turn, like Bri2k1 said. It is physically NOT possible to simulate this in a stationary simulator (and by stationary I mean where the hydraulic arms are bolted to the floor of the building).

You can theoretically simulate it by making the simulator go straight up on the hydraulics. Whether it has the specs to handle a whole extra G (and for how long) I do not know.

Quoting Grbld (Reply 36):
Your body helps the sim a great deal in fooling you, but it's always good to keep it in perspective: There are things that the sim can't simulate.

Of course. But we're only talking simulator limitations. There's no theoretical reason you can't simulate high G conditions, as long as the simulator has enough range of motion. The reason sims aren't built this way is cost/benefit.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
SK973
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RE: Full Motion Simulators

Sat Apr 29, 2006 7:38 am

Quoting Starlionblue (Reply 30):
Fighter sims do need to simulate "unusual attitudes" quite a bit but the solution in some cases is not to simulate movement at all apart from visually.

Only fighter sim I've flown is the Swedish Air Force's JA37 which uses a system of air pillows in the bottom and back of the seat and tightening the seat belt straps. That along with wearing a G-suit did provide a very realistic illusion of sustained G-forces.

Another way of creating real sustained G-forces would be to build a sim using a G-accelerator like the ones used to test G-forces on people. Heard a rumor that such a sim has actually been built recently but I don't know if it's true or not.

Quoting Starlionblue (Reply 34):
Dream job for some non-pilot aviation buffs here would be sim tech. I have met one. He works for a sim facility and performs daily maintenance on the simulators. Part of his job is ensuring they work properly after any maintenance. He's pretty good at flying

Now, who might that be?  Wink

Quoting Starlionblue (Reply 1):
Having spent a few hours in a 767 sim and a Bell 206/406 sim,

It was a Bell 212/412!  Wink
 
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Starlionblue
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RE: Full Motion Simulators

Sat Apr 29, 2006 9:13 am

Quoting SK973 (Reply 38):
Quoting Starlionblue (Reply 1):
Having spent a few hours in a 767 sim and a Bell 206/406 sim,

It was a Bell 212/412!

Yeah yeah  Wink
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo
 
speedracer1407
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RE: Full Motion Simulators

Sat Apr 29, 2006 5:00 pm

Quoting Grbld (Reply 36):
SNBru, while your vestibular system senses acceleration in 3 dimensions, the g-forces you feel in a turn, you feel on your body and your joints. Do a 60-degree bank turn in any plane, whether a Cessna or a Boeing and you'll feel the g-forces pushing every part of your body down, most noticeably your arms with which you're holding the yoke and throttle/thrust levers. As any pilot will know, these g-forces are just the thing that make steep turns difficult. Now whether you NEED that kind of thing on a Boeing or Airbus simulator is a whole different story, but my point is that it's not possible to simulate it on a normal Level D sim.

This is exactly what I was looking for. Thanks everyone for your replies. This was an interesting discussion, and I learned a lot.

I guess my original question could have been phrased better. My real curiosity was just how well these sims replicate g-force, AND whether or not it's important. Acceleration and deceleration seems pretty straight foreward, but thos aren't forces that a pilot is disoriented or confused by. My imagination told me that perhaps one of the most difficult things about recovering from highly unusual attitudes was the potentially high G-forces that not only make it difficult to maintain dexterity, but also might override procedural actions and instrument reading. I imagined a pilot recovering from inverted flight, hanging by his shoulder straps, blood filling his head, and figured that such a situation would be compromised by a sim that reaches its roll stops at 30 degrees. As an occaisonal weekend racer, I thought about the idea of practicing on a stationary sim; shooting apexes, learning judicious throttle conrole, learning braking points, etc. But throw in 2 Gs of lateral acceleration into the mix in a REAL car, and all of that can suddenly go out the window. G-force can be helpful in reading levels of adhesion, but can also be disorienting.

It seems that the general consensus, however, is that simulators don't need to replicate sustained positive and negative G to be adequately educational, and thus, as in most situations, the automotive analogy doesn't apply to aviation. Thanks again for the discussion.

By the way, some of you suggested that it didn't take "a lot of money" to take a short ride in a level D sim. Is it really that cheap? Keep in mind that I'm a graduate student. So a few hundred dollars for an hour is a no-go


O
Dassault Mercure: the plane that has Boeing and Airbus shaking in their boots.
 
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Starlionblue
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RE: Full Motion Simulators

Sat Apr 29, 2006 9:45 pm

Quoting Speedracer1407 (Reply 40):
By the way, some of you suggested that it didn't take "a lot of money" to take a short ride in a level D sim. Is it really that cheap? Keep in mind that I'm a graduate student. So a few hundred dollars for an hour is a no-go

It's probably at least that. Ask your parents for it when you turn 25 (or 30)  Wink

Then again, ask for a ride in an aerobatic plane. This probably costs less and is at least as much fun.
"There are no stupid questions, but there are a lot of inquisitive idiots." - John Ringo

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