Board index FlightGear Development Aircraft

737-300 Classic - New and Improved

Questions and discussion about creating aircraft. Flight dynamics, 3d models, cockpits, systems, animation, textures.

Re: 737-300 Classic - New and Improved

Postby zakalawe » Fri Nov 01, 2013 8:29 am

e-pilot wrote in Thu Oct 31, 2013 9:07 pm:The EADI and the EHSI in the 300 are in very poor shape - I have only minimally started improving them. In fact they are so bad right now I have been looking for replacements but haven't found a suitable candidate yet. Would be terrific if you get the 757's working well. Might be a candidate for a replacement for the 733.

The code side is pretty simple, especially because Gijs has done the hard work! For the EHSI the appearance is very similar to the more modern NDs, for the EADI I would benefit from more example images. (Airliners.net had surprisingly few good ones) There seem to be many configurations out there, especially speed & altitude tapes vs 'fast/slow pointers'. Also images of the different AFDS annunciation would help, I can guess these but the layout when several re active+armed would help.

But the main thing is I need to get comfortable using Inkscape, bah :)
zakalawe
 
Posts: 1161
Joined: Sat Jul 19, 2008 4:48 pm
Location: Edinburgh, Scotland
Callsign: G-ZKLW
Version: next
OS: Mac

Re: 737-300 Classic - New and Improved

Postby Honzaku » Sat Nov 02, 2013 1:24 pm

Hello e-pilot and guys,

I have to say again, I am very happy that someone finally take over this aircraft and continue in the developement. But if you want to implement a new feture into your model, please, spend some time by studying the real thing before you start to model or simulate it.
I've recently downloaded the latest version from e-pilots site and try it. I noticed the airspeed control cursor knob has been added to the airspeed indicator gauge. I checked it out and found it is used in absolutely wrong way. Same wrong way it is used in B 707-400/300 model.
So what is wrong. You've mixed up several features of the airsped indicator: Vmo pointer (hand), airspeed markes, and airspeed cursor. You've basically used the Vmo pointer (red and white hand) as a speed marker used for nothing but the speed reminder for pilot which can be adjusted by airspeed coursor knob.

But real thing works as follow:

Red-white hand is Vmo pointer and shows maximal operating speed - the speed which shouldn't be never deliberately exceeded. No surprise, this cannot be set by a pilot by any means. It is driven directly or (as in this aircraft) through the flight computer from pitot static system. This is because airliners operate in broad ranges of altitudes and therefore in broad ranges of static pressures and temperatures. The INDICATED airspeed displayed by airspeed indicator depends on the static pressure and temperature and threrfore on the altitude. With rising altitude the indicated airspeed drops down whilst the TRUE (real) aircraft speed relative to the ambient air stays same. So does the Vmo. In the simulator, this pointer should be simulated simmilar way to the altimeter. Create for example some look-up table with pressure altitudes and related Vmo values to control the pointer.

The knob in left bottom corner. This operates the airspeed cursor bug. The orange bug which is not included in your model. See for example page 549 and 550 of this document:
http://www.lt-vacc.org/images/mesti/Boe ... Manual.pdf
or photo of real B737 airspeed meter:
Image
The bug shows comanded airspeed for autothrottle and can be also set also from the autopilot/flight director panel by airspeed knob.

Airspeed markers (white bugs around the dial in the photo):
Also not included in your model. These are intended for the purpose you've used the Vmo pointer. Pilot can set these markers as desired usually to remind himself some important speeds, for example Vref at the approach. In real aircraft you can slide these bugs around the dial for example by the nail.

Cheers

Honza
Last edited by Honzaku on Sun Nov 03, 2013 8:40 am, edited 1 time in total.
Honzaku
 
Posts: 83
Joined: Sat Jan 14, 2012 5:00 pm
Location: Between LKPR and LKVO, Czech Republic

Re: 737-300 Classic - New and Improved

Postby e-pilot » Sat Nov 02, 2013 7:04 pm

Thank you Honza - good information - I did not create the original ASI but I did add the animation for the VMO marker and as you pointed out I did do that incorrectly. I will implement some method to rotate the VMO marker automatically from the flight computer and add a bug which will be controllable by the knob. The airspeed markers are a bit beyond my skill level at the moment as they will require some complex layering to prevent them from overlapping/passing one another but I will certainly keep them in mind and when my blender skills improve adequately I will attempt it. Thank you for your input!

P.S. does the bug move automatically with the programmed Autothrottle setting and if moved by the knob does that change the autothrottle setting?
User avatar
e-pilot
 
Posts: 18
Joined: Wed Feb 15, 2012 2:15 am
Location: PHKO
OS: Deb/Win

Re: 737-300 Classic - New and Improved

Postby Honzaku » Sun Nov 03, 2013 2:20 pm

Hello e-pilot,

there are two modes for airspeed coursor selected by the airspeed cursor knob (in the ASI left bottom corner) position:

The knob is pushed - automatic mode: The coursor is fully driven by autopilot/autothrottle system. It just mirrors the speed value shown in IAS/MACH window on the MCP panel. Nothing more, nothing less.

The knob is pulled - manual mode: When pulled it becomes rotateable. By rotating it, you can set the speed cursor in the ASI manually. Speed value set on MCP panel stays unaffected by this - you cannot overide any settings on MCP panel throug this knob. The speed cursor stays in manually set position until the knob is pushed back again. Once pushed back, the cursor is reset automatically to reflect the speed value set on the MCP panel.

And what autothrotlle does?
If it is engaged in airspeed mode it tries to achieve the speed set by the airspeed cursor and than keep it, no matter what is the cursor set by.

The question is if manual setting of airspeed cursor can affect other features of autothrottle like i.e. stall prevention. If the flight computer recognizes the ACF approaching stall, no matter what autothrottle mode is engaged, this funcion automatically skip the autothrottle to airspeed mode and also auomatically set the target speed to minimal safe speed for current airplane config and than adjust thrust to achieve it. My opinion is that manual settings of ASI are ignored in this case. But I dont know that surely, just think.

Basically, in my opinion manual positioning of cursor from the ASI is used very rarely today. You can do so from MCP panel as well, and there are no extra features brought by this ASI knob. Probably its more or less historical herritage.

Cheers

Honza
Honzaku
 
Posts: 83
Joined: Sat Jan 14, 2012 5:00 pm
Location: Between LKPR and LKVO, Czech Republic

Re: 737-300 Classic - New and Improved

Postby Disasterman » Wed Nov 06, 2013 4:49 pm

Hello everybody and thanks for this aircraft. I downloaded it but I am afraid I can't fly it....

I make a route with rout manager, I take off and when I engage the auto pilot the bird goes crazy making zig-zag for some seconds until it dives due to the high bank angle. Also another thing that I noticed is that when I disengage auto pilot the yokes stay at the spot they where when the autopilot was working. For example if the plane was rolling left when I disengage the yokes don't turn right manually.

I use FG 2.12 64bits. Can anyone help me?

Edit: I am sorry the problem is that I had ticked Auto-coordinate, now it works normaly!
Disasterman
 
Posts: 11
Joined: Tue Oct 08, 2013 8:02 am
Location: Greece
Callsign: EUR265
Version: 2.12.0
OS: Windows 8

Re: 737-300 Classic - New and Improved

Postby clrCoda » Fri Nov 22, 2013 9:35 am

Disasterman wrote in Wed Nov 06, 2013 4:49 pm:Edit: I am sorry the problem is that I had ticked Auto-coordinate, now it works normaly!



I wonder if e-pilot might consider adding the disable auto coordinate property to his set.xml and then display this fact on load of the plane.

Taking this idea a bit further, developers of planes where autopilots could be fouled by the auto coordinate setting might add to their autopilots definitions a phrase to read the current setting of auto coordiation when the auto pilot is engaged, turn auto coord off, and then if the autopilot is disengaged, or if the feature of the autopilot that is most at risk by having the auto coord engaged, if that feature of the autopilot is disabled, to have the original condition of the auto coordination re-established.

This idea could be incorporated in several of the jets I've flow. I typically do this myself using the properties browser. Most recently the setting can be found in "controls/flight", but auto coordination had been in several different parts of the properties tree, usually under "flight" but sometimes under "sim"

This would go a long way to help those FlightGear pilots using keyboards or joysticks without pedals.


I'm one of the testers of many versions of e-pilots developments of the 737-300 and can convey my complete satisfaction.

Much thanks for the plane, Mark!
Ray St. Marie
clrCoda
 
Posts: 1228
Joined: Wed Apr 07, 2010 11:04 am

Re: 737-300 Classic - New and Improved

Postby clrCoda » Sat Nov 23, 2013 8:20 am

As it turns out, the real solution to this problem is to add an autocoord toggle in the AP menu. I'm implementing this locally for testing and then I'll post something about it and send the fix up for someone to include in subsequent versions of FG.
Ray St. Marie
clrCoda
 
Posts: 1228
Joined: Wed Apr 07, 2010 11:04 am

Re: 737-300 Classic - New and Improved

Postby Honzaku » Sat Nov 23, 2013 10:13 am

Hello guys,

Regarding to the autocordination. The autocoordination should be disabled completely for all modern airliners. All of them use wing spoilers in conjunction with ailerons to cordinate the turn. So the turns are always coordinated and correct turns in modern airliners are steered ONLY by yoke with NO pedal action. Pedals are use only in some special maneuvres like crosswid landings or steering the plan on the runway during the takeoff or landing roll. Use of pedals in normal flight turns has even adverse effect, since it discoordinates the turn which is allready coordinated by spoilers.

Cheers

Honza.
Honzaku
 
Posts: 83
Joined: Sat Jan 14, 2012 5:00 pm
Location: Between LKPR and LKVO, Czech Republic

Re: 737-300 Classic - New and Improved

Postby Soitanen » Fri Nov 29, 2013 11:30 am

Honzaku, I have deep look into 737-300 FDM, and found, that there are no stabilizer setting. So trimming is not right, because it make changes in elevator setting, not stabilizer, as in reality.
As I see by your other post to forum, you are good knowing Boeing's and info about FDM. I can't understand one moment - can "feel and centering unit" move yoke column? I mean neutral position. As I feel in procedural simulator of B738, there wasn't neutral shift. I just trim aircraft and move column to neutral. Is this right? Or it must be like in Tu-154 - I move column to needed position, and trimming make my forces to keep yoke less, and after trim finish column stay in new position?
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
Boeing 737-800. WIP. Canvas PFD and ND.
Antonov An-24B. Made from scratch. Very good FDM. 3D model by Adrian. WIP.
Project Russia (some cities, based on OSM with custom objects).
Soitanen
 
Posts: 489
Joined: Sat Jun 16, 2012 6:50 am
Location: Saint-Petersburg, Russia
Version: git
OS: Linux Mint 17

Re: 737-300 Classic - New and Improved

Postby Honzaku » Sat Nov 30, 2013 11:21 pm

Hi Soitanen,

Soitanen wrote in Fri Nov 29, 2013 11:30 am:Honzaku, I have deep look into 737-300 FDM, and found, that there are no stabilizer setting. So trimming is not right, because it make changes in elevator setting, not stabilizer, as in reality.
As I see by your other post to forum, you are good knowing Boeing's and info about FDM. I can't understand one moment - can "feel and centering unit" move yoke column? I mean neutral position. As I feel in procedural simulator of B738, there wasn't neutral shift. I just trim aircraft and move column to neutral. Is this right? Or it must be like in Tu-154 - I move column to needed position, and trimming make my forces to keep yoke less, and after trim finish column stay in new position?


I as long as I understend it well, it works like this:
In all cases, except one, the neutral position of the control column is still the same. This is related to the neutral position of the elavator which is the position when the elevator is aligned with stabilizer. The exception is mach trimming. Mach trimming works on very simillar principple as Tu-154 "normal" trimming works. The whole assembly of feel and centering unit is slightly rotated by mach trim actuator to change the neutral position of control column. This is reflected also to the neutral position of the elevator, which is now slightly angled to the stabilizer.

The artifical feel unit of 737 consist of two main units: The Feel unit:

Image

The unit consists of the frame (magenta color?) which is pivotally mounted to the airplane frame at the point which looks like COG symbol. In this point, also the arm is mounted on the shaft which allows it to rotate relatively to the feel unit frame as well as to the aircraft frame. On the left side, the arm has mechanical link to the controll column. Concentric with the shaft the cam is mounted on the arm. By deflecting the column either the side we rotate the cam which results in extending of the spring and we also press against the oil pressure in the hydraulic cilinder on the bottom of the picture. the mechanism of levers and connecting rods which provides the link between the cam and cilinder is mounted in the feel unit frame. So deflecting the colum we always have to overcome the foce of the spring and the pressure of hydraulic fluid.

Whilst the force of the spring is rigidly given by the spring characteristic, the pressure of fluid is controlled by the second main unit of artifical feel - The (mechanical) feel computer which adjust the pressure according to the airspeed - the higgher the speed - the higgher the pressure. The computer also contains the trim feel mechanism which continuously reliefs the fluid pressure as the stabilizer is moving to the trimmed position during trimming. If mach trimming occurs the whole frame is rotated by mach trim actuator, which changes the neutral position of column and the elevator neutral position.

BTW: You have probably good insight to the russian FG comunity. Do you know, if there is some progress in the IL-76 or Yak-40 developement? Will these great models be finished sometimes to a level of Tu-154. And regarding to IL-76, is it possible to download some working version now? Thanks.

Some links to study regarding the artifical feel:

http://www.737flightsim.com/737center.html

and pages 191 to 196 of this textbook:

http://www.avsim.su/f/documents-16/jaa- ... 30918.html
Honzaku
 
Posts: 83
Joined: Sat Jan 14, 2012 5:00 pm
Location: Between LKPR and LKVO, Czech Republic

Re: 737-300 Classic - New and Improved

Postby GhostAviation » Tue Dec 03, 2013 3:17 pm

I would like to help you with the 737 classic as a modeler. I have experience in blender and also a bit of AC3D but mostly i use blender. I started making textures and everything but I thought I would first ask you about the modeling before starting. So tell me what you think and I will reply.
GhostAviation
 
Posts: 5
Joined: Tue Dec 03, 2013 3:11 pm
OS: Mac OSX Mountain Lio

Re: 737-300 Classic - New and Improved

Postby e-pilot » Sat Dec 07, 2013 3:22 am

GhostAviation wrote in Tue Dec 03, 2013 3:17 pm:I would like to help you with the 737 classic as a modeler. I have experience in blender and also a bit of AC3D but mostly i use blender. I started making textures and everything but I thought I would first ask you about the modeling before starting. So tell me what you think and I will reply.


Yes certainly - any and all help welcome - the interior needs a bit of help and the cockpit interior and window frames especially. Still need a galley and bluerooms fore and aft as well. Post links to your beautiful creations here and we can merge them into the plane.
User avatar
e-pilot
 
Posts: 18
Joined: Wed Feb 15, 2012 2:15 am
Location: PHKO
OS: Deb/Win

Re: 737-300 Classic - New and Improved

Postby Soitanen » Mon Dec 23, 2013 4:57 pm

About FDM.

I made new function in FDM, which calculates lift to drag ratio:
Code: Select all
        <function name="aero/function/K">
      <quotient>                   
                  <sum>
                    <property>aero/coefficient/CLalpha</property>
                    <property>aero/coefficient/dCLflap</property>
                    <property>aero/coefficient/CLde</property>
                  </sum>
                  <sum>
                    <property>aero/coefficient/CD0</property>
                    <property>aero/coefficient/CDi</property>
                    <property>aero/coefficient/CDmach</property>
                    <property>aero/coefficient/CDflap</property>
                    <property>aero/coefficient/CDgear</property>
                    <property>aero/coefficient/CDsb</property>
                    <property>aero/coefficient/CDsp</property>
                    <property>aero/coefficient/CDbeta</property>
                    <property>aero/coefficient/CDde</property>
                    <property>aero/coefficient/CDrv</property>
                  </sum>
      </quotient>
        </function>

And what did I find: at approach K (lift to drag ratio) with gear down and flaps full seem to be normal, about 7-8. Near ground it start to raise up to 21! I understand, that this is ground effect, but it seems to be too big (for me). I this case aircraft even with full flaps don't want to loose speed near earth and continue flying.

What do you think about it?
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
Boeing 737-800. WIP. Canvas PFD and ND.
Antonov An-24B. Made from scratch. Very good FDM. 3D model by Adrian. WIP.
Project Russia (some cities, based on OSM with custom objects).
Soitanen
 
Posts: 489
Joined: Sat Jun 16, 2012 6:50 am
Location: Saint-Petersburg, Russia
Version: git
OS: Linux Mint 17

Re: 737-300 Classic - New and Improved

Postby daveculp » Thu Dec 26, 2013 1:36 am

Good catch Soitanen. Check the ground effect on lift table. Some older versions of table had a typo giving huge ground effect boost near the ground (I think it was an off-by-ten-times error due to decimal point in wrong place). The 747 had this too some years ago and was almost impossible to land.
User avatar
daveculp
 
Posts: 503
Joined: Sun Feb 24, 2013 1:50 am
Location: Las Vegas, USA
Callsign: DCulp
Version: 2017.3.1
OS: Ubuntu 17.10

Re: 737-300 Classic - New and Improved

Postby Soitanen » Fri Dec 27, 2013 9:17 am

Found error.
It was in kCDge section - 0.0480 instead of 0.48.

e-pilot, please, make changes in fdm file. Here is right section:
Code: Select all
<function name="aero/function/kCDge">
            <description>Change_in_drag_due_to_ground_effect</description>
            <product>
                  <table>
                      <independentVar>aero/h_b-mac-ft</independentVar>
                      <tableData>
                          0.0000   0.480
                          0.1000   0.5150
                          0.1500   0.6290
                          0.2000   0.7090
                          0.3000   0.8150
                          0.4000   0.8820
                          0.5000   0.9280
                          0.6000   0.9620
                          0.7000   0.9880
                          0.8000   1.0000
                      </tableData>
                  </table>
            </product>
        </function>
Boeing 737-300. Reworked cockpit, FDM, autopilot and much more. WIP.
Boeing 737-800. WIP. Canvas PFD and ND.
Antonov An-24B. Made from scratch. Very good FDM. 3D model by Adrian. WIP.
Project Russia (some cities, based on OSM with custom objects).
Soitanen
 
Posts: 489
Joined: Sat Jun 16, 2012 6:50 am
Location: Saint-Petersburg, Russia
Version: git
OS: Linux Mint 17

PreviousNext

Return to Aircraft

Who is online

Users browsing this forum: Google [Bot] and 2 guests