Board index FlightGear Development Aircraft

Working on the 787...

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

Working on the 787...

Postby nickyivyca » Mon May 24, 2010 4:29 am

I've done a couple things to the 787. Corrected the FDM, added a Pushback, and added contrails. Which work. But one thing has changed with these improvements: Elevator spazzing.

Before working the 787, I would have to go up to more than 300 KIAS to get the elevators to spazz. Which is when they slowly increase up, then slam down after they suddenly start taking action, with the AP doing this. The same thing happens in joystick mode at these high speeds, so I know it's not the AP. With the FDM improvements, the spazz speed is about 250, below cruising, which means that I I need to use the inflight speedbrakes during cruise. What parameters in the FDM need to be changed to make this elevator spazz speed go back to being about 300-320 KIAS?

Here's the current 787 with my edits that I'm flying. It includes the new version with the edits (Boeing 787-8), the old version (Boeing 787 (STOL)), and an attempt at an MP copilot (Boeing 787-8 First Officer), which still needs a lot of work to make useable.

http://www.mediafire.com/?mzmxymovkvg

Note that this version *will not* work with 2.0. I fly 1.9.1 so I edited a version compatible with 1.9.1. The pushback will work, as I included those files with this 787. They should be mapped into use, as well.

Once this problem is solved, I may take further 787 development into my own hands, as the original maker seems to have stopped working on it. Once I finalize cockpit mappings, animations, and more stuff, I may try my hand at tweaking the model, then stretching the model and editing the rest of the aircraft files to make a 787-9.

Some screenshots of improvement:
I used the same contrails from the 737-300. First test:
Image
I accidentally used the same y axis point instead of the opposite point for the contrail coordinates. Now they work.
Image
...even when the engines aren't running. :lol: :P
And pushback:
Image
After first being implemented. I may have slightly changed the location of the model.
Personal Fleet: 787-8, CRJ-200, 737-300, MD-81, DHC-3A, Beechcraft Starship
New hangar!
Curent projects: New 787, New CRJ-200, DC-9, New 777-200ER FDM
User avatar
nickyivyca
 
Posts: 1256
Joined: Tue Dec 29, 2009 5:42 am
Location: Near KSFO, closer to KPAO
Callsign: Nick, ---206
Version: 2
OS: Win 7 (64)

Re: Working on the 787...

Postby redneck » Mon May 24, 2010 3:52 pm

Nice job. I like how you named the old version STOL. It's fitting, considering that it could land on Nimitz with low fuel. Being that it's my favorite plane to fly, I'm very interested in seeing how this turns out. Be sure to release a new version once that spaz issue is worked out.
Call Signs: redneck, ATCredn (unspecified freq atc)
FGFSCopilot
FGFSCopilotATCEdition
System Specs
Model: Alienware M15x, OS: Windows 7 Professional 64-bit, RAM: 3 GB, CPU: Intel i3 quad core at 2.4 GHz, GPU: Nvidea GeForce GTX 460M 1.5 GB GDDR5
redneck
 
Posts: 3630
Joined: Mon Feb 02, 2009 2:17 am
Location: Pennsylvania, USA
Version: 240

Re: Working on the 787...

Postby simbabeat » Mon May 24, 2010 8:56 pm

The spaz issue might be because it is basic aeromatic and needs more added to it. It's jsbsim right?
User avatar
simbabeat
 
Posts: 3435
Joined: Sat Sep 12, 2009 12:19 am

Re: Working on the 787...

Postby redneck » Mon May 24, 2010 9:25 pm

I'm pretty sure it's JSBsim. I tend to gravitate towards planes with a JSBsim fdm anyways. They just feel more natural to me than YAsim. But, he did say he corrected the FDM, and I know the plane had FDM updates from the previous author, which leads me to believe that this plane does NOT have a simple Aeromatic fdm. I never really thought of the spaz problem as well spazzing out. I did notice that the vertical control surfaces became VERY sensitive at high speeds. It was kinda like going from flying a comfortable airliner to being in the cockpit of the Su-37 in less than a second, except, at those speeds, the 787 loved to climb, and the controls were so sensitive that not only was it impossible to maintain a constant altitude both automatically or manually, but also a constant pitch, as though it had actually become more sensitive than the Su-37. Then, I learned how to fly realistically and never had the problem again.

Btw, I was just thinking, it would be pretty cool if a real STOL jetliner was developed.
Call Signs: redneck, ATCredn (unspecified freq atc)
FGFSCopilot
FGFSCopilotATCEdition
System Specs
Model: Alienware M15x, OS: Windows 7 Professional 64-bit, RAM: 3 GB, CPU: Intel i3 quad core at 2.4 GHz, GPU: Nvidea GeForce GTX 460M 1.5 GB GDDR5
redneck
 
Posts: 3630
Joined: Mon Feb 02, 2009 2:17 am
Location: Pennsylvania, USA
Version: 240

Re: Working on the 787...

Postby kyokoyama » Mon May 24, 2010 10:00 pm

Agreed...
You know, I don't think any of the good planes have a Elev. Spaz at all...could you remove it, perhaps?
Look for "B-BIRD" "N127KY" or "AVA0004" -that's me.

Despite having over 1700 posts here, I am not even close to being the most skilled guy here... I'm just words and bad drawing, not experience. :P
kyokoyama
 
Posts: 1988
Joined: Sun May 03, 2009 2:16 am
Location: Earth
Callsign: B-BIRD, N127KY
Version: 2.12.1
OS: Windows Vista

Re: Working on the 787...

Postby simbabeat » Mon May 24, 2010 10:07 pm

That's the thing kyoko. We don't know what is causing it.
User avatar
simbabeat
 
Posts: 3435
Joined: Sat Sep 12, 2009 12:19 am

Re: Working on the 787...

Postby nickyivyca » Tue May 25, 2010 2:53 am

It's definitely YASim. The main thing that is confusing me is that I'm pretty sure the spazzing was at a much higher speed in the version labeled STOL. The only thing I did to the FDM (I think) was reduce the engine thrust from 90500 to 63800, make the wing sweep be 32 degrees instead of 29, and add the pushback thruster. I may have also changed the main weight, and that would be about it.
Personal Fleet: 787-8, CRJ-200, 737-300, MD-81, DHC-3A, Beechcraft Starship
New hangar!
Curent projects: New 787, New CRJ-200, DC-9, New 777-200ER FDM
User avatar
nickyivyca
 
Posts: 1256
Joined: Tue Dec 29, 2009 5:42 am
Location: Near KSFO, closer to KPAO
Callsign: Nick, ---206
Version: 2
OS: Win 7 (64)

Re: Working on the 787...

Postby Buckaroo » Tue May 25, 2010 3:39 am

Nick,

You've got way too much elevator authority in your FDM. Use the command line YASim and try to get your Approach Elevator value much closer to -0.9 or so. Your current value is -0.07, which is like giving the AP (or anything else trying to control the plane) a huge hammer to trim the plane-- the PID controller can't fine-tune pitch because it isn't being given the ability to make fine adjustments. This becomes more noticeable as airspeed increases, until finally you get the porpoising effect.

I suggest first make sure your flight surface dimensions and placement are correct (Melchior's Blender plug-in that displays YASim surface locations as Blender objects gives a great visual feedback on this) and that you have a reasonable CG, then try reducing the elevator's lift value. I also suggest trying to eliminate the hstab effectiveness value altogether if possible. If these things don't help, you likely have deeper issues to resolve first. Note that -0.9 Approach Elevator is just a rough target-- you'll have to fine-tune this and other factors to get the landings speeds close to the numbers for the real thing.

If you do some searches on Detlef Faber's posts, you'll find more good info on this topic.

-Buck
Callsign: Buckaro(o)
Author: Lockheed 1049H Constellation, Grumman Goose, MD-81, Edgley Optica, Velocity XL RG, YASim Guide
User avatar
Buckaroo
 
Posts: 475
Joined: Fri Jan 18, 2008 6:45 am
Location: Bloomington IN USA
Callsign: Buckaro(o)
Version: 2.10
OS: Windows & Linux

Re: Working on the 787...

Postby nickyivyca » Tue May 25, 2010 4:28 am

Well, one thing isn't correct-the placement of the FDM elevators. So I tested this by putting a cone marker model where the FDM shows the elevator to start (you have to reverse the X coordinates, which I did) and here's where it showed up.

Image

I'm assuming that the FDM start location is the front of the root of the elevator, right? I surely want to have these elevators in the right place in the FDM before trying anything else.

EDIT: The same is true with the vstab. Looks like someone changed the model without changing their FDM when they first built the plane!

Maybe even the same thing with the wing, as well. The marker cone is buried deep in the center of the wing. I'll recoordinate the wing, hstab, and vstab.

For now, the elevator will be moved to the X coordinate of -23 in the FDM. Random fact: -23.4 was the original location of the elevator in the FDM, before it was commented out and replaced with this wrongly placed one! So I'll move it back to -23.4 now.
Personal Fleet: 787-8, CRJ-200, 737-300, MD-81, DHC-3A, Beechcraft Starship
New hangar!
Curent projects: New 787, New CRJ-200, DC-9, New 777-200ER FDM
User avatar
nickyivyca
 
Posts: 1256
Joined: Tue Dec 29, 2009 5:42 am
Location: Near KSFO, closer to KPAO
Callsign: Nick, ---206
Version: 2
OS: Win 7 (64)

Re: Working on the 787...

Postby Buckaroo » Tue May 25, 2010 5:04 am

Nick,

YASim flight surface xyz location should be mid-chord of the root, not leading edge.

I've attached a snapshot of what I see when I view the FDM's idea of the model against the actual model, it might be helpful. Note also that the fuselage could stand a little clean-up of the nose and the missing tail cone section, and the engine nacelles are located at wing level and are probably too large to represent something like the drag profile of a typical low-drag hollow engine nacelle.

I'm guessing that probably happens a lot, where the FDM and model get out of sync with each other.

Hope this helps.

-Buck
Callsign: Buckaro(o)
Author: Lockheed 1049H Constellation, Grumman Goose, MD-81, Edgley Optica, Velocity XL RG, YASim Guide
User avatar
Buckaroo
 
Posts: 475
Joined: Fri Jan 18, 2008 6:45 am
Location: Bloomington IN USA
Callsign: Buckaro(o)
Version: 2.10
OS: Windows & Linux

Re: Working on the 787...

Postby nickyivyca » Tue May 25, 2010 6:12 am

That definitely is useful. I'll have more time to do some more work tomorrow, I'm done working on the 787 for the night. To-do list is first positioning the elevators in the right spot.

Thanks Buck!

-nick
Personal Fleet: 787-8, CRJ-200, 737-300, MD-81, DHC-3A, Beechcraft Starship
New hangar!
Curent projects: New 787, New CRJ-200, DC-9, New 777-200ER FDM
User avatar
nickyivyca
 
Posts: 1256
Joined: Tue Dec 29, 2009 5:42 am
Location: Near KSFO, closer to KPAO
Callsign: Nick, ---206
Version: 2
OS: Win 7 (64)

Re: Working on the 787...

Postby ChocBoy » Tue May 25, 2010 8:14 pm

I get the dreaded "0 length fuselage" error when I launch FG.......got 2.0. Any idea on what can be done to get it 2.0-compatible?
Account locked by self soon. Taking a break from FG. If you want to contact me, email me. Please don't hesitate. Anything, email.
Thank you.
User avatar
ChocBoy
 
Posts: 854
Joined: Sat May 30, 2009 3:17 pm
Callsign: ChocBoy

Re: Working on the 787...

Postby ChocBoy » Tue May 25, 2010 9:06 pm

Ok, for those of you who are using this for 2.0, here is a solution. Replace EVERYTHING in the 787.xml with this; don't worry, all of Nick's features are still included.

787.xml:

Code: Select all
<!--787 yasim

Specs:
or  75,000 lb GENXs
or  75,000 lb Rolls-Royce Trent 1000s

Typical Cruise = 0.85 Mach / 35000 ft
Max Speed = 0.87 / 35000 ft
Wing span: 60.10m
Length: 56.7 m
Tail Height: 16.97m
Diameter : 5.74 m
Wing Area: 427.8m2
Max Fuel :33,528 US gal
Max TO weight: 484,000 lbs
http://www.boeing.com/commercial/airports/787.html
TO speed : 145 kt
Landing speed : 131 kt

Mach 1 = 576.6 kt @ 35,000 ft -->

<!--airplane mass="240000"-->
<airplane mass="252500">

<!-- Approach configuration -->
<approach speed="120" aoa="7">
  <control-setting axis="/controls/engines/engine[0]/throttle" value="0.2"/>
  <control-setting axis="/controls/engines/engine[1]/throttle" value="0.2"/>
  <control-setting axis="/controls/flight/flaps" value="1.0"/>
  <control-setting axis="/controls/flight/slats" value="1.0"/>
  <control-setting axis="/controls/gear/gear-down" value="1"/>
  <solve-weight idx="0" weight="350"/>
  <solve-weight idx="1" weight="45000"/>
</approach>

<!-- Cruise configuration -->
<cruise speed="501" alt="35000">
  <control-setting axis="/controls/engines/engine[0]/throttle" value="0.8"/>
  <control-setting axis="/controls/engines/engine[1]/throttle" value="0.8"/>
  <control-setting axis="/controls/flight/flaps" value="0.0"/>
  <control-setting axis="/controls/gear/gear-down" value="0"/>
  <solve-weight idx="0" weight="350"/>
  <solve-weight idx="1" weight="45000"/>
</cruise>

<cockpit x="24" y="0.5" z="2.1"/>

<fuselage ax="25.91" ay="0" az="0.1" bx="23.0" by="0.00" bz="0.6"
          width="3.6" taper="0.0" midpoint="1.0"/>
<fuselage ax="25.91" ay="0" az="0.1" bx="23.0" by="0.00" bz="1.2"
          width="3.6" taper="0.0"/>
<fuselage ax="23.0" ay="0" az="0.6" bx="16.0" by="0.00" bz="1.4"
          width="5.9" taper="0.62" midpoint="0.8"/>
<fuselage ax="23.0" ay="0" az="1.2" bx="16.0" by="0.00" bz="1.4"
          width="5.9" taper="0.62"/>
<fuselage ax="16.0" ay="0" az="1.4" bx="-13.6" by="0.00" bz="1.4"
          width="5.9" taper="1.0" midpoint="0.4"/>
<fuselage ax="-13.6" ay="0" az="1.4" bx="-29.338" by="0.00" bz="2.12"
          width="5.9" taper="0.1" midpoint="0"/>

<fuselage ax="8.3" ay="9.65" az="1.1" bx="-1.8" by="9.8" bz="1.1"
          width="3.8" taper="1.0"/>
<fuselage ax="8.3" ay="-9.65" az="1.1" bx="-1.8" by="-9.8" bz="1.1"
          width="3.8" taper="1.0"/>


<!--wing x="2.5" y="3.0" z="0.35" length="29.8" chord="11.15" sweep="29"
      taper=".13" dihedral="8" camber="0.05" incidence="0"-->
<wing x="2.5" y="3.0" z="-0.35" length="29.8" chord="11.15" sweep="29"
      taper=".13" dihedral="8" camber="0.005" incidence="1.25">
  <stall aoa="15" width="8" peak="1.5"/>
  <flap0 start="0" end=".56" lift="1.6" drag="1.9"/>
  <flap1 start=".64" end=".88" lift="1.3" drag="1.2"/>
  <slat start="0" end="1" aoa="2" drag="1.1"/>
  <spoiler start="0.2" end="0.6" lift="0.3" drag="2.0"/>
  <control-input axis="/controls/flight/flaps" control="FLAP0"/>
  <control-input axis="/controls/flight/aileron" control="FLAP1" split="true"/>
  <control-input axis="/controls/flight/aileron-trim" control="FLAP1" split="true"/>
  <control-input axis="/controls/flight/slats" control="FLAP0"/>
  <control-input axis="/controls/flight/spoilers" control="SPOILER"/>
  <control-output control="FLAP0" prop="/surface-positions/flap-pos-norm"/>
  <control-output control="FLAP0" prop="/surface-positions/slats"/>
  <control-output control="FLAP1" side="left"
        prop="/surface-positions/left-aileron-pos-norm"/>
  <control-output control="FLAP1" side="right"
        prop="/surface-positions/right-aileron-pos-norm"/>
  <control-speed control="FLAP0" transition-time="10"/>
</wing>

<!--hstab x="-23.4" y="1.35" z="1.95" chord="5.3" length="10.1" taper=".30"
       sweep="35" dihedral="7.0" effectiveness="2.0" incidence="-1.25"-->
<hstab x="-31.4" y="1.35" z="1.95" chord="5.3" length="10.1" taper=".30"
       sweep="25" dihedral="7.0" effectiveness="2.0" incidence="0">
  <stall aoa="15" width="2" peak="1.5"/>
  <flap0 start="0" end="1" lift="1.5" drag="1.2"/>
  <control-input axis="/controls/flight/elevator" control="FLAP0"/>
  <control-input axis="/controls/flight/elevator-trim" control="FLAP0"/>
  <control-output control="FLAP0" prop="/surface-positions/elevator-pos-norm"/>
</hstab>

<vstab x="-30.2" y="0.00" z="3.76" chord="6.6" length="10.6" taper="0.35"
       sweep="33" effectiveness="1.5">
  <stall aoa="15" width="2" peak="1.5"/>
  <flap0 start="0" end="1" lift="1.3" drag="1.3"/>
  <control-input axis="/controls/flight/rudder" control="FLAP0" invert="true"/>
  <control-input axis="/controls/flight/rudder-trim" control="FLAP0" invert="true"/>
  <control-output control="FLAP0" prop="/surface-positions/rudder-pos-norm"
        min="1" max="-1"/>
</vstab>

<jet x="7" y="9.63"  z="-0.85" mass="7500" thrust="90500" egt="810" tsfc="0.125">
  <control-input axis="/controls/engines/engine[0]/throttle" control="THROTTLE"/>
  <control-input axis="/controls/engines/engine[0]/reverser" control="REVERSE_THRUST"/>
  <!--control-input axis="/controls/engines/engine[0]/condition" control="CONDLEVER"/-->
  <!--control-input axis="/controls/engines/engine[0]/starter" control="STARTER"/-->
<actionpt x="2" y="9.63" z="-0.85"/>
</jet>

<jet x="7" y="-9.63"  z="-0.085" mass="7500" thrust="90500" egt="810" tsfc="0.125">
  <control-input axis="/controls/engines/engine[1]/throttle" control="THROTTLE"/>
  <control-input axis="/controls/engines/engine[1]/reverser" control="REVERSE_THRUST"/>
  <!--control-input axis="/controls/engines/engine[1]/condition" control="CONDLEVER"/-->
  <!--control-input axis="/controls/engines/engine[1]/starter" control="STARTER"/-->
<actionpt x="2" y="-9.63" z="-0.85"/>
</jet>
<!-- APU -->
<jet x="-26.5" y="0"  z="2" mass="300" thrust="50" egt="810" tsfc="0.9" n1-idle="80" n2-idle="85">
   <control-input axis="/controls/engines/engine[2]/throttle" control="THROTTLE"/>
</jet>

<!-- nose -->
<gear x="20.56"  y="0.00" z="-3.2"
      compression="0.75" spring="0.7" damp="4">
  <control-input axis="/controls/flight/rudder" control="STEER" square="true"/>
  <control-input axis="/controls/gear/gear-down" control="EXTEND"/>
  <control-output control="EXTEND" prop="/gear/gear[0]/position-norm"/>
  <control-speed control="EXTEND" transition-time="7"/>
</gear>

<gear x="-1.97" y="4.88" z="-3.85" compression="1.1">
  <control-input axis="/controls/gear/brake-left" control="BRAKE"/>
  <control-input axis="/controls/gear/brake-parking" control="BRAKE"/>
  <control-input axis="/controls/gear/gear-down" control="EXTEND"/>
  <control-output control="EXTEND" prop="/gear/gear[1]/position-norm"/>
  <control-speed control="EXTEND" transition-time="7"/>
</gear>

<gear x="-1.97" y="-4.88" z="-3.85" compression="1.1">
  <control-input axis="/controls/gear/brake-right" control="BRAKE"/>
  <control-input axis="/controls/gear/brake-parking" control="BRAKE"/>
  <control-input axis="/controls/gear/gear-down" control="EXTEND"/>
  <control-output control="EXTEND" prop="/gear/gear[2]/position-norm"/>
  <control-speed control="EXTEND" transition-time="7"/>
</gear>


<!--tank x="2" y="6.5" z="0.65" jet="true" capacity="50000"/>
<tank x="2" y="-6.5" z="0.65" jet="true" capacity="50000"/>
<tank x="3.5" y="0" z="1.0" jet="true" capacity="110000"/-->
<tank x="0" y="7.5" z="0.65" jet="true" capacity="52000"/>
<tank x="0" y="-7.5" z="0.65" jet="true" capacity="52000"/>
<tank x="0" y="0" z="-1" jet="true" capacity="120000"/>



<!--ballast x="21.0"  y="0" z="1" mass="18000"/-->
<ballast x="21.0"  y="0" z="1" mass="15000"/>
<ballast  x="-3" y="5.0"  z="0" mass="1500"/>
<ballast  x="-3" y="-5.0"  z="0" mass="1500"/>

<weight x="15" y="0" z="2" mass-prop="/consumables/payload/forward-passengers-pounds"/>
<weight x="1" y="0" z="2" mass-prop="/consumables/payload/center-passengers-pounds"/>
<weight x="-8" y="0" z="2" mass-prop="/consumables/payload/aft-passengers-pounds"/>
<weight x="11.25" y="0" z="-0.5" mass-prop="/consumables/payload/fwd-cargo-pounds"/>
<weight x="-14.5" y="0" z="0" mass-prop="/consumables/payload/aft-cargo-pounds"/>


<!--pushback-->

 <thruster x="20.56"  y="0.00" z="-3.2" vx="1" vy="0" vz="0" thrust="20000">
 <control-input axis="/sim/model/pushback/target-speed-fps" control="THROTTLE" src0="-1" src1="1" dst0="-1" dst1="1"/>
 </thruster>

</airplane>


And, of course, the proof:

Image
:D :D :D
Account locked by self soon. Taking a break from FG. If you want to contact me, email me. Please don't hesitate. Anything, email.
Thank you.
User avatar
ChocBoy
 
Posts: 854
Joined: Sat May 30, 2009 3:17 pm
Callsign: ChocBoy

Re: Working on the 787...

Postby redneck » Tue May 25, 2010 10:23 pm

You're forgetting that this plane has switched authors before, which may be the reason for some of the odd findings. I never did like the version from UFW.
Call Signs: redneck, ATCredn (unspecified freq atc)
FGFSCopilot
FGFSCopilotATCEdition
System Specs
Model: Alienware M15x, OS: Windows 7 Professional 64-bit, RAM: 3 GB, CPU: Intel i3 quad core at 2.4 GHz, GPU: Nvidea GeForce GTX 460M 1.5 GB GDDR5
redneck
 
Posts: 3630
Joined: Mon Feb 02, 2009 2:17 am
Location: Pennsylvania, USA
Version: 240

Re: Working on the 787...

Postby simbabeat » Tue May 25, 2010 10:39 pm

The version from UFW was the best for me. It had an interior and perfect AP, no spazzing out.
User avatar
simbabeat
 
Posts: 3435
Joined: Sat Sep 12, 2009 12:19 am

Next

Return to Aircraft

Who is online

Users browsing this forum: Baidu [Spider], Robertfm and 1 guest