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Post by hanspetter on Jul 13, 2009 7:23:37 GMT -5
This has been covered many times before but it doesn't hurt to look into it again  All flighsim boards will discuss panel views, especially in connection with being able to see the runway during a final. There are various cheats as pulling the panel down, bumping up the scenery or going "W" to see where you're going. While any sim can be set to provide the required view real pilots must accept what they've got. I guess you could stretch your neck to be able to see a bit more but that's hardly necessary in real life. I assume that real flightdecks provide a perfectly sufficient view provided the glideslope is reasonable. In sims the problem tends to get worse during finals for two reasons, 1) the plane is flying at a high angle of attack and 2) you really need to be able to view the runway I'll certainly keep cheating if that's what it takes but I know that real aircraft can't possibly present this problem. What is a realistic panel height to provide a real-life over-the-panel view? Is it less than half the screen from top to bottom? When I modify panels to cover no more than 40 - 50% of the screen it seems about right. I really need to be able to monitor the airspeed though. While virtual cockpits can be adjusted by zooming in you may end up losing the airspeed instrument before the panel top gets comfortably low. |
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Post by Tom Goodrick on Jul 13, 2009 10:29:53 GMT -5
I have always tried to put fair realism into my panel view on final but sometimes I err on the side of showing too much ground. In real airplanes the view varies somewhat from trainers flown by low-time pilots to business and commercial planes flown by pros.
One of the things real pilots do NOT do is to change their seat position when starting final. Sliding seats are very dangerous in airplanes and any seat motion at such a critical time would get you in trouble during a check ride. (Remember real pilots get checked all the time.)
Real pilots are taught to live with a reduced view over the panel. It is mostly a view of the sky. On most modern planes you can watch a mid point on the runwa as you come in on final but your view of the runway will often be blocked when you flare. You may be able to see the end of the runway during the flare if the designer is kind to you. When all wheels are on the runway, you have an adequate view ahead but not a generous one. Do pilots sit up straighter on final or when taxiing, of course they do, raising their viewpoint by as much as an inch.
In FS we have three ways of adjusting the final approach view when we develop the FD files for an aircraft. (I speak only of the 2D Panel as I never use the virtual panel.)
(1) The angle of view should be tilted downward slightly. There is a line that should be in every panel.cfg file as shown below that sets the view angle down a little, in this case, 1.5 degrees:
[views]
view_forward_dir=1.5
In some cases this may be as much as 3.0 degrees. The positive value shown here is an angle downward, below the horizon.
(2) The pitching moment change with flaps should be positive (which brings the nose downward in steady flight). This is done in the .air file with the line shown below. The amount is very small as it is per radian operating on a small decimal value.
Cm_df Pitch Moment - Flaps = 0.1
(3) We can adjust the vertical position of the bottom of the outside view. Look in the panel.cfg file and you will find these lines near the bottom:
[Default View]
X=0
Y=0
SIZE_X=8191
SIZE_Y=4500
That SIZE_Y=4500 is often a value of 2700 which narrows the vertical field of view permitting you to see a lot closer to the front of the aircraft than you should. Try this when sitting parked on the ramp with some objects in front of you. Tap W to get a full-screen view ahead. That is the view that should exist of the world in front of you if the components of the aircraft were somehow stripped away. Note the appearant aspect ratio of the objects in front of you. Now tap W again to return to the old view over the panel. Do the aspect ratios of objects change? Probably. This value of 4500 seems to work to get the right view of the world when looking over the 2D panel. The other adjustments mentioned above may be needed even more but don't give yourself too generous a view. In the King Air, I can only see the gorund about 50 ft ahead of the aircraft. I think this is about right. I have looked into the cockpit but have not actually sat in the pilot's seat of the King Air. i'd welcome any coments by King Air pilots.
I just made this change and made a flight in the King Air with all other adjustments as noted above. My landing speed components were 107.3 KIAS and -74 fpm at gross. It worked fine but I did not see a lot of grass in front of the runway.
These examples are for my Beech Model 200B twin turboprop which is set up for flight by professional pilots.
Let's consider why these changes are the only correct ones to make. The reason you should not move the pilot's seat in flight has already been covered. It is very dangerous to mess with this in flight. Indeed, the seat must be locked before takeoff. Because of the flat relations existing in the 2D panel, a downward view is more natural than a level view. Some may think I am giving in too much to the sim hobbiest. But a slight downward angle seems rather natural during taxi operations for tri-gear aircraft. Indeed the taxi view is probably the best cue to the proper setting of this angle. You cannot change the view position coordinates because the sim will move the 2D panel to the same relation to the view point. You can "raise the seat" but that will change anytime you switch between internal and external views.
It is an exaggeration to say the angle of attack increases significantly on final approach. It should not. Lift increases to allow slow flight but that added lift comes mainly from the deployment of flaps which create higher lift at the same angle of attack. The change in pitch moment with flaps should compensate for this. Note tht this is not a simple rotation. There is a change in moment with flap deflection but to maintain steady flight, the pilot compensates by adjusting the stick position and/or the pitch trim so the aircraft does not pitch up much and may even pitch down slightly as shown here. Getting this right can be tricky and calls for several trials.
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Ed Burke
Member
Healthy living is fine, but it's having fun that keeps us going!
Posts: 433
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Post by Ed Burke on Jul 13, 2009 16:52:40 GMT -5
The 2D panel view is totally unrealistic in that we are viewing the instruments at 90*. What we are really seeing in an aircraft are apparently oval instruments due to the angle of view. Accepting this fact, if we squash the panel some by dragging it up and then raising the bottom edge before dragging down again we have effectively increased our forward visibility and given ourselves a more realistic environment.
Ed
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Post by Tom Goodrick on Jul 14, 2009 9:29:48 GMT -5
I'd be curious as to your wife's opinion since I understand she has left-seat pilot time in many aircraft. I find this trick of lowering the bottom of the unseen part of the outside view adds realism. I am going through my aircraft and checking the view with values of Y= 3600 to 4500. As I recal in most complex aircraft the pilots view axis is just above the top of the panel. To enable the pilot to see us, we US Navy linemen stood well off to the left of center even for aircraft like the T-28.
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Post by flaminghotsauce on Jul 14, 2009 11:01:17 GMT -5
This gets into the reason I don't like the 2d panel. I love using the VC because I can set the view the same as if I'm in the cockpit. One can watch the instruments and still see the runway with peripheral vision or vice-versa. In the real life 172 there is always plenty of runway in view until the final moments of flaring. At this point, one should be looking down toward the end of the runway so the shorter view out in front is irrelevant. I find the VC is quite accommodating in this regard. I can shift the view down slightly with the hatswitch so I can see the airspeed or whatever without losing sight of the runway view.
I can barely use the 2d panel anymore. The 3d is so much better, and more realistic. FSX is even better than FS9 too, as the panning is way faster. This is handy while flying downwind.
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Post by Tom Goodrick on Jul 14, 2009 11:02:13 GMT -5
I just finished adjusting the view for my Cessna 340 and Cessna 414. Both use a down view angle of 2.0. The Y setting for the screen is 3600 and, in the .air file, the Pitch moment with flaps is .025 and with gear is .01. These are changes from the original.
You lose the view of the runway when you flair.
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Post by hanspetter on Jul 14, 2009 11:43:39 GMT -5
Regarding Ed's comment why a squashed panel is more realistic I remembered that some modern jet panels are actually slanted. That is, when you look down to read instruments you'll be looking more or less straight at the primary instruments with negligible foreshortening. This would seem to be the best way to construct a panel which begs the question, why aren't they all slanting forward toward the windshield? A vertical panel will always cause a foreshortened view, especially when you're sitting close and looking down. Thus, a little "scrunching" of FS panels may be a good idea. Regarding the claim that 3D panels are superior I agree as view configurability is concerned. The downsides are their use of system resources and (often) poorer readability.
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Post by Tom Goodrick on Jul 14, 2009 15:54:09 GMT -5
Two things first: The lack of increase in angle of attack when the flaps are extended to fly slower and then a view of my panels with lowered Y positions. Here is a table of pameters during level flight at reduced speed in the Cessna 414: Power__Flaps__Gear__KIAS__PTrim__AoA 75%____0d____Up____185___-1.4____1.4d 55%____"_____"______161___0.9_____2.3d 45%____"_____"______147___2.8_____3.0 50%____15d___"______127___5.4_____3.0 Then here is the view on final for the Cessna 414 with Y=3600 and the aircraft flying the ILS with 30 degrees of flaps.  It is hard to judge in photos the height of the panel relative to the height of the pilot's eyeballs. But I would guess in most professional aircraft it is about 6 inches and in most private aircraft it is as high as 8 or 9 inches. Today's glass panels have helped by reducing the space required to hold the display of required information. the pilot is not looking down at much of an angle at an instrument except for the bottom row. this does not give him or her much of an angle of view down over the top of the panel. But it is tough to tell in many cases because of the camera angle - normally looking down at both pilot and panel. In one case pilot of a commuter airliner was leaning his forearm on the top of the panel while turned slightly back toward the camera. It was obvious from the bend at his shoulder that his arm went up slightly from the shoulder to the top of the panel. I may be reducing the down view too much but I am sure most of us have been using too much of a ground view "over the nose." In the approaches flown with the C340 and C414 today, I learned not to expect to see much grass in front of the runway from 1/2 mile out. You should be looking at a point on the runway 1/3 down toward the far end until you flare. Then you can easily lose the view of the end of the runway momentarily until the aircraft is on the mains. |
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Post by hanspetter on Jul 15, 2009 13:16:19 GMT -5
Tom, are you sharing updated airfiles? We could always do the listed changes ourselves but these files are really small...
Regarding the angle of view being tilted downwards, why is that? What we want is to learn to live with the correct view and practice landings with the exact same view as real pilots. Then, is a downward view realistic for the right reasons or is it a sim compromise to compensate for obtrusive 2D panels?
How the aircraft react to flaps is crucial here. Should they all stay at a low angle of attack when properly trimmed for slow flight? If so, a lot of sim aircraft don't behave. Since this entire discussion depends on AoA as well as panel height / view tilt we should ensure that the flaps response is correct. Modifying the panel / view is a moot point if a given aircraft flies at a high AoA when it shouldn't.
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Post by Tom Goodrick on Jul 15, 2009 20:41:22 GMT -5
Tom, are you sharing updated airfiles?
No, I won't be updating my posted files for a while. You can type in the two or three numbers needed. Maybe later I'll update the posted files.
Regarding the angle of view being tilted downwards, why is that?
I found it helpful. Pilots don't look out the window along a horizontal body-axis. They look down a little when they are interested in seeing the runway.
Then, is a downward view realistic for the right reasons or is it a sim compromise to compensate for obtrusive 2D panels?
It is a good idea. While making these adjustments, I noticed it moved the V axis mark I use in an appropriate way.
How the aircraft react to flaps is crucial here. Should they all stay at a low angle of attack when properly trimmed for slow flight? If so, a lot of sim aircraft don't behave.
You think of angle of attack as the only thing that increases lift. But camber also increases lift and that is how flaps do their job. The entire purpose of flaps is to provide additional lift that enables an aircraft to fly slowly. The added lift makes the plane try to fly up. The pilot compensates by lowering the nose to keep it reasonably level. There are moment changes with flap deflection. These are generally downward. But these are small compared to the adjustments the pilot can make. Thus, the exact inertial anglular changes are complex and vary between aircraft and pilots.
But I think 90% of the FD files available for download and poorly done. Not much you can do but fix your files as you see fit using the info presented here.
Since this entire discussion depends on AoA as well as panel height / view tilt we should ensure that the flaps response is correct.
Bear in mind angle of attack has little to do with it in the sim. A basic angle of attack is determined from the velocity vector and pitch rotations of the vehicle. This gives a lift coefficient from the lift curve (#404). Then a portion of the flap lift increment (in proportion to the amount of flap deflected) is added to that lift coefficient. This determines with the dynamic pressure the lift force acting on the aircraft.
Pay attention to the pitch motions the next time you ride a plane to a landing. Watch the FS aircraft from the spot view from the side as you repeat reruns of the landings. Consider all this.
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Post by hanspetter on Jul 16, 2009 16:03:34 GMT -5
I just did the mods myself and I'm pretty frustrated at the moment  I was hoping that the answer would be that we ought to see more ground than I did from the aircraft that made me start this thread. However, these mods made the Cessnas into the exact category of planes that I can't land safely. I tried several finals and stayed above the glideslope as long as I could, hoping to be able to see enough as I throttled down. It didn't work out. I ended up crashing short of the runway several times since I failed to see what I was doing. If this is the way it should be there's no way I can watch the VASI lights all the way down. I'll have to aim for the far end of the runway. If that's the way it should be I'll try to get used to it but it won't be easy. Still, I'll rather keep practicing with the current set-up if that's the way it should be  |
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Post by Tom Goodrick on Jul 16, 2009 18:49:57 GMT -5
You wanted realism. I suspected this would reduce rather than increase the amount of grass you see in front of the runway. But look at my photo for the Cessna 414. You should be able to land with a view like that. Everything you need is in view. The VASI lights are good to look at most of the way. Then 1/2 mile out you should be looking at the point where you want to touch down - about 1/4 down the runway. That point should be just above the panel.
I hope you did not think that Size_Y=4500 should be set for all aircraft! That was the setting that works for the Beech B200 which is notorious for not giving pilots a generous view over the nose. That is the only change I made in the King Air b200 to get a realistic view. It is a little tight but i made a landing using it and did not find it extremely difficult. However, it does demand that you know what you are doing with regard to configuration control and power control on final to keep the airspeed tightly controlled.
If you use full flaps, you'll need power to fly a normal glideslope and the view will not be generous. But with a good Cm_flap, it should be possible. We all need to work at this because many of us have been cheating with a better view than real pilots get.
Here are some complete sets of numbers for aircraft we like to fly:
______________Cessna_____Beech_________Cessna________Beech________Beech
______________182S_______V35B__________414A__________Baron 58______350
View Angle____2.0_________1.5____________2.0____________0.5___________2.0
Size_Y=_______3000_______3000___________3600___________3400_________4000
Cm_gear______N/A________0.007___________0.01___________0.02_________0.03
Cm_flap_______0.03________0.011__________0.025__________0.08__________0.08
KIAS (Lndg)____69.77_______82.37__________90.11__________92.75_________98.01
FPM__________-99_________-173___________-203___________-81___________-125
(I adjusted the flap aero on the Beech 350 slightly in the .air file: CD_gear=0.030 and CL_flap=0.75.)
The landing speeds are given just to show I was able to make ordinary landings with each one. When you fly the Cessna 182S, take a good look at the C182S and its pilot from the spot view from a point ahead of the plane and from the side of the plane. The pilot does not have a lot of down angle. This is in contrast to the Beech 350 where there is a better angle (which fits my glass panel.) (Unfortunately, in the real 350 with a glass panel, they have the standard high panel and just leave a lot of blank space around the displays.)
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Post by hanspetter on Jul 18, 2009 18:42:06 GMT -5
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Post by flaminghotsauce on Jul 18, 2009 20:07:25 GMT -5
In the Cessna 172, there is a runway in the center of the windscreen. Those photos, Hans, are a good representation of that. It was the standard training meme "keep the runway in the middle" at my school. In the flare, I kept the far end of the runway in sight while I slowly raised the top of the panel up to meet it. I usually touched tires right before they coincided in my view.
Faster heavier aircraft will be different than my experience, but those photos show much similar while on approach.
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Post by Tom Goodrick on Jul 18, 2009 21:25:37 GMT -5
Those photos show what I expected. But it is a little hard to compare to what we see in the FS cockpit because of the zoom factor in the lens of the camera. The certainly are wider than a 50mm (normal) lens on a 35mm camera. I'd say 35mm in the first photo (A320) and 28 or 24mm in the Piper.
Try the numbers I posted above. I'll get some numbers for jets.
Flaming, are most instructors tell you to keep the middle of the runway centered in the view, not the whole runway! Try the Cessna 182 numbers I have above. They seem right to me for a Cessna though the 182 has just a bit more panel/engine than the 172.
Here are number sets for two more aircraft:
________________Learjet 45___Piper Archer II
View Angle_________3.0________3.5
Size_Y=__________4000_______3000
Cm_gear__________0.02________N/A
Cm_flaps__________0.06________0.10
KIAS_____________123.0_______66.15
FPM______________-123.0______-56
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