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Erickson S-64 Aircrane anyone?

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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Tue May 21, 2019 10:03 pm

I took the first step of making a JSBSim version of AirCrane today. I successfully added the Alouette-III FDM to the AIrCrane file structure and was able to autostart and fly the AirCrane with the Alouette-III FDM. No animations and the AirCrane started sunk into the ground about half way its height due to different positioning systems between YASim and JSBSim.
There is tons of work to do to make this even close to realistic. But I got far enough today to get some motivation to hopefully keep going.
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Re: Erickson S-64 Aircrance anyone?

Postby Octal450 » Tue May 21, 2019 10:30 pm

wlbragg wrote in Tue May 21, 2019 10:03 pm:different positioning systems between YASim and JSBSim.

Nope, its due to the FDM being setup and balenced for the A III 3d, not the aircrane's 3d. Its FDM to 3d specific, not YA to JSB.

Kind Regards,
Josh
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed May 22, 2019 1:04 am

Hi Josh,
Hum, i guess you thought I did a poor job in stating why the AirCrane model is sunk into the ground! I do know the exact reason.
Specifically, it is because the contact points I am using in the FDM file are indeed the point positions for the Alouette-III and I haven't adjusted them.
When I stated the following
due to different positioning systems between YASim and JSBSim

what I meant was that YASIm uses a different syntax to position the gear
Code: Select all
  <gear x="8.295" y="0" z="-4"
        compression="0.1"
        spring="3"
        damp="1.0"
        sfric="1.5"
        dfric="0.8">
        <control-input  control="STEER" axis="/controls/flight/rudder" square="true" src0="-1" dst0="-1.0" src1="1" dst1="1.0"/>
        <control-output control="STEER" prop="controls/gear/steering"/>
  </gear>

  <!-- left gear -->
  <gear x="1.190" y="3.237" z="-4"
        compression="0.1"
        spring="3.2"
        damp="1.0"
        sfric="1.5"
        dfric="0.8"
        initial-load="1">
        <control-input control="BRAKE" axis="/controls/gear/brake-left"/>
        <control-input control="BRAKE" axis="/controls/gear/brake-parking"/>
  </gear>


JSBSim uses the following syntax

Code: Select all
  <ground_reactions>
    <contact type="BOGEY" name="LEFT"> <!--cp 00-->
      <location unit="M">
        <x> 0.90 </x>
        <y>  -1.1926</y>
        <z> -1.32694 </z>
      </location>
      <static_friction>    0.8  </static_friction>
      <dynamic_friction>   0.5 </dynamic_friction>
      <rolling_friction>   0.02  </rolling_friction>
      <spring_coeff unit="LBS/FT">        5000 </spring_coeff>
      <damping_coeff unit="LBS/FT/SEC">   1200</damping_coeff>
      <retractable>1</retractable>
      <brake_group> LEFT </brake_group>
    </contact>
    <contact type="BOGEY" name="RIGHT"> <!--cp 01 -->
        <location unit="M">
            <x> 0.90 </x>
            <y> 1.1926 </y>
            <z>-1.32 </z>
        </location>
        <static_friction>    0.8 </static_friction>
        <dynamic_friction>   0.5  </dynamic_friction>
        <rolling_friction>   0.02  </rolling_friction>
        <spring_coeff unit="LBS/FT">        5000 </spring_coeff>
        <damping_coeff unit="LBS/FT/SEC">   1200 </damping_coeff>
        <retractable>1</retractable>
        <brake_group> RIGHT </brake_group>
    </contact>
    <contact type="BOGEY" name="NOSE"> <!--cp 02-->
        <location unit="M">
            <x> -2.207  </x>
            <y>     0.0 </y>
            <z>  -1.32694  </z>
        </location>
        <static_friction>    0.8</static_friction>
        <dynamic_friction>   0.5  </dynamic_friction>
        <rolling_friction>   0.02  </rolling_friction>
        <spring_coeff unit="LBS/FT">         6000 </spring_coeff>
        <damping_coeff unit="LBS/FT/SEC">    2000</damping_coeff>
        <max_steer unit="DEG"> 30.00 </max_steer>
        <retractable>1</retractable>
        <brake_group> NONE </brake_group>
    </contact>
    <contact type="BOGEY" name="TAIL-BUMPER"> <!--cp 03-->
        <location unit="M">
            <x>  6.00652 </x>
            <y> 0.0 </y>
            <z> -0.60059 </z>
        </location>
        <static_friction>    0.8</static_friction>
        <dynamic_friction>   0.5  </dynamic_friction>
        <rolling_friction>   0.02  </rolling_friction>
        <spring_coeff unit="LBS/FT">         2000 </spring_coeff>
        <damping_coeff unit="LBS/FT/SEC">    150</damping_coeff>
    <retractable>1</retractable>
        <brake_group> NONE </brake_group>
    </contact>


So technically they do use a different system to position gear, at least different syntax. The system that is positioning the AirCrane model's gear contact points presently is the JSBSim system setup for the Alouette-III. The system setup for the AirCrane model is no longer being used.

Hopefully that clears this up for anyone following now or at a later date.
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Re: Erickson S-64 Aircrance anyone?

Postby Octal450 » Wed May 22, 2019 1:11 am

Yes, that is correct. I thought you meant it was difference because YASim vs JSB, not due to the XYZ. :) But KEEP IN MIND - you need to adjust far more than just the ground reactions. CG, AeroRP, etc must be all changed.

Kind Regards,
Josh
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed May 22, 2019 1:22 am

CG, AeroRP, etc must be all changed

Yes, that is the tip of the iceberg. Eventually I intend to change everything in the FDM from an Alouette-III to AirCrane. This is something I have been wanting to do for a long time.
I will miss the handling characteristics of the YASim version though. I really do like the ease in which it flies although it does have a few glitches in it.
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed May 22, 2019 4:34 am

Now it's getting exciting.
I repositioned the Aircrane model to match the Alouette profile, more or less. Added some basic rotor animation tied to the JSBSim FDM. Installed Amelia, she is working! Now some major cleanup, some massaging of the textures and effects and we will have Amelia available in the AirCrane engineer seat or as the pilot with ourself in the engineer seat.
What we will end up with in the short term is all the current functionality of the AirCrane but Alouette-III FDM and autopilot with Amelia.

I'm going to have to whack Amelia upside the head to get her to hover at a higher altitude than she currently thinks is appropriate. I've tried to convince her that we need to be able to hover at any altitude to do our work, but she is really stubborn.
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Re: Erickson S-64 Aircrance anyone?

Postby Thorsten » Wed May 22, 2019 5:21 am

I've tried to convince her that we need to be able to hover at any altitude to do our work, but she is really stubborn.


For most helicopters, hover relies on the ground effect - as the ground effect decreases with altitude, a given collective setting corresponds to an equilibrium hover altitude (and that is what Amelia utilizes).

Not every helicopter has the power to hover at any altitude (clearly the Aircrane has...) - but there the equations would have to be different - collective has to manage vertical speed and the vertical speed target must depend on the altitude error. Amelia doesn't know that, therefore she can't hover outside the ground effect region (and I don't know whether the Alouette has enough juice to hover at altitude anyway...)
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed May 22, 2019 5:01 pm

I've tried to convince her that we need to be able to hover at any altitude to do our work, but she is really stubborn.

I didn't actually look at the code, I just kept yelling at her to "hover higher". :)
I already knew there was a limit, but I didn't know exactly where it was.

[quote] I don't know whether the Alouette has enough juice to hover at altitude anyway.../quote]
Ah, that will certainly make a difference until the FDM gets adjusted.

I'll look at the trigger for the hover height being exceeded and see if I can understand what you did and maybe add another mode that doesn't use "ground effect"?
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Re: Erickson S-64 Aircrance anyone?

Postby Thorsten » Wed May 22, 2019 5:19 pm

I'll look at the trigger for the hover height being exceeded and see if I can understand what you did and maybe add another mode that doesn't use "ground effect"?


Something like that, yeah - it's not very difficult, you just have to be aware of the transition that's happening.
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed May 22, 2019 9:42 pm

Here is a test using Amelia as the pilot. There is still much to be done to get the JSBSim version working correctly.
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Re: Erickson S-64 Aircrance anyone?

Postby Maerchenprinz » Wed May 22, 2019 10:23 pm

wlbragg wrote in Wed May 22, 2019 4:34 am:Installed Amelia, she is working!

Do you think I could install Amelia here at my home, too, and make her hoover? The carpet needs a little bit of cleaning...
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Thu May 23, 2019 12:41 am

Rumba! :lol:
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Mon Jun 03, 2019 3:40 am

Doing a little work on the cargo for the AirCrane. This is a 4 piece stackable model consisting of a the base, tower, generator, hub and blades assembly. I was able to erect it using the YASim version of the AirCrane. It's time to clean the cargo hauling and stacking code up so it is more user friendly. I also want to add some new options to it.

Image
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Re: Erickson S-64 Aircrance anyone?

Postby Michat » Tue Jun 04, 2019 2:07 am

That screeny should be hover up to SOTM. :!:
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Re: Erickson S-64 Aircrance anyone?

Postby wlbragg » Wed Sep 11, 2019 4:48 pm

Thanks to D-ECHO you can now see the GIT version of the AirCrane in the launcher list. It was a bug I've been searching for for a very long time. A really simple mistake but hard to find. It was basically a path error to the flight recorder. There was also an inadvertent path to nowhere that I had introduced while working on some ideas locally that got through to the dev repo.
A new pull should get you the GIT version of the AirCrane in your launcher list now.
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