Outerra forum

Please login or register.

Login with username, password and session length
Advanced search  

News:

Outerra Tech Demo download. Help with graphics driver issues

Author Topic: jsbsim additional moments due to force applied not at CoG  (Read 6215 times)

bomber

  • Hero Member
  • *****
  • Posts: 503
  • newbie
jsbsim additional moments due to force applied not at CoG
« on: July 23, 2014, 05:14:21 pm »

Hi guys,

Code: [Select]
<location name="AERORP" unit="IN">
<x> 0.0 </x>
<y> 0.0 </y>
<z> 0.0 </z>
</location>
<location name="VRP" unit="IN">
<x> 0.0 </x>
<y> 0.0 </y>
<z> 0.0 </z>
</location>

    </metrics>

    <mass_balance>
        <ixx unit="SLUG*FT2"> 1000000 </ixx>
        <iyy unit="SLUG*FT2"> 1000000 </iyy>
        <izz unit="SLUG*FT2"> 1000000 </izz>
        <emptywt unit="LBS"> 100000 </emptywt>
        <location name="CG" unit="IN">
            <x> 0 </x>
            <y> 0 </y>
            <z> 0 </z>
        </location>

As you can see any force I apply is at the CoG point 0,0,0

However I'm seeing additional moments of rotations specifically the pitch, but roll to some degree....

I'm using an identical fdm (no code changes) to one used in Flightgear, in Flightgear there's no additional moments, but in Outerra there are..

Can the devs look into this ?

If you tell me what version of JSBsim we're using I'll ask on the jsbsim forum for them to have a look see, cause I can't see how an Outerra installation of a 'black box' jsbsim application can be anything but a jsbsim fault....

Then again.....

regards

Simon
Logged
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell

alialiali

  • Jr. Member
  • *
  • Posts: 49
Re: jsbsim additional moments due to force applied not at CoG
« Reply #1 on: July 24, 2014, 06:08:21 am »

I'd check the fuel tank locations. I believe they contribute to the balance as far as I know.
Logged
Boeing 727 - In Development (On Hold)

Intel Core i7 4790K 4.4GHz
Nvidia GTX 970
16GB RAM

bomber

  • Hero Member
  • *****
  • Posts: 503
  • newbie
Re: jsbsim additional moments due to force applied not at CoG
« Reply #2 on: July 24, 2014, 07:43:21 am »

No fuel tank.
Logged
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell

bomber

  • Hero Member
  • *****
  • Posts: 503
  • newbie
Re: jsbsim additional moments due to force applied not at CoG
« Reply #3 on: July 28, 2014, 03:41:26 pm »

Can I ask..

Is the lack of response because of...

a) It's being looked at be patient.
b) Don't believe your observations so not looking at.
c) Gone fishing be back next week.
d) Didn't understand the problem.

I'm only asking as I don't want this to fall into a black hole.
Logged
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell

TheLoneExplorer

  • Jr. Member
  • *
  • Posts: 26
  • newbie
Re: jsbsim additional moments due to force applied not at CoG
« Reply #4 on: July 28, 2014, 09:35:44 pm »

Just keep bumping my friend :)

BUMP
Logged
“Man cannot discover new oceans unless he has the courage to lose sight of the shore.”
― André Gide

cameni

  • Brano Kemen
  • Outerra Administrator
  • Hero Member
  • *****
  • Posts: 6618
  • Pegs is clever, but tae hain’t a touch sentimental
    • outerra.com
Re: jsbsim additional moments due to force applied not at CoG
« Reply #5 on: July 29, 2014, 12:01:46 am »

Angrypig gone fishing, and only he can answer that (if it's a problem in OT).
Logged

ZeosPantera

  • ||>>-Z-<<||
  • Global Moderator
  • Hero Member
  • *****
  • Posts: 2518
  • #1 Outerra Fan Boy
    • My Youtube
Re: jsbsim additional moments due to force applied not at CoG
« Reply #6 on: July 29, 2014, 12:44:35 am »

Gone fishing.. OR "Is swimming with the fishes" as we italians are prone to saying.
Logged
"Fear accompanies the possibility of death, Calm shepherds its certainty" - General Ka Dargo

Jagerbomber

  • Hero Member
  • *****
  • Posts: 1478
Re: jsbsim additional moments due to force applied not at CoG
« Reply #7 on: July 29, 2014, 01:10:43 am »

Did the sharks or piranhas like the pork more?
Logged
"Perhaps this speaks to some larger trend within society today...  A prevailing desire on the part of indie developers to recreate the entire world into one where you can charge more than $15 for your game design degree coursework." - Yahtzee ;) :P

PytonPago

  • Hero Member
  • *****
  • Posts: 2253
  • It´s way too complex, dont let me try to explain !
Re: jsbsim additional moments due to force applied not at CoG
« Reply #8 on: July 29, 2014, 01:36:55 am »

Just wait you two till Angry comes with a half-ton of fish. :D

Logged
We are still undeveloped as long as we don´t realize, that all our science is still descriptive, and than beyond that description lies a whole new world we just haven´t even started to fully understand.

bomber

  • Hero Member
  • *****
  • Posts: 503
  • newbie
Re: jsbsim additional moments due to force applied not at CoG
« Reply #9 on: August 10, 2014, 04:04:47 pm »

When you do get back from fishing, don't spend any time on this I'm still experimenting, it might be something else... need to investigate more..

Regards

Simon.

Logged
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell

bomber

  • Hero Member
  • *****
  • Posts: 503
  • newbie
Re: jsbsim additional moments due to force applied not at CoG
« Reply #10 on: August 11, 2014, 01:56:36 pm »

ok this is resolved JSBsim's working correctly.
Logged
"If anyone ever tells you anything about an aeroplane which is so bloody complicated you can't understand it, take it from me - it's all balls" - R J Mitchell