Board index FlightGear Development Weather

Maximum possible lift??  Topic is solved

Everything related to weather simulation, visuals should be discussed in the shader subforum.

Maximum possible lift??

Postby gierschi@flightgear » Tue Apr 05, 2016 9:52 am

Hey guys,

what is the maximum possible negative or positive lift (sum of ridge lift, thermal lift and wave lift) you can get in FlightGear? Can the vertical wind velocity influence an passenger plane (like A320) a lot or is it exclusive for gliders?

best regards,
Sebastian
gierschi@flightgear
 
Posts: 58
Joined: Tue Nov 03, 2015 10:40 pm

Re: Maximum possible lift??

Postby Thorsten » Tue Apr 05, 2016 11:43 am

I don't think it's limited in any way, FG will simulate whatever you ask it to. I'm not entirely sure about what will occur in practice, updrafts in thunderstorms can be of the order of 12-14 m/s I suppose.

And it'll lift anything that doesn't run on a magic FDM, I've felt noticeable thermals with an F-16 in-sim.
Thorsten
 
Posts: 12490
Joined: Mon Nov 02, 2009 9:33 am

Re: Maximum possible lift??

Postby gierschi@flightgear » Fri Apr 08, 2016 11:41 am

Okay, and is it correct, that the FG property ''/environment/wind-from-down-fps'' is positive when the wind is coming from down (a thermal/lift) and negative when you have a wind blowing in the direction of the ground. And simultaneously the properties ''/fdm/jsbsim/atmosphere/total-wind-down-fps'' and ''/fdm/jsbsim/atmosphere/turb-down-fps'' are negativ when the wind or turbulent portion is coming from down and positive when the wind blows in the direction of the ground? So the definition is exactly the other way around in JSBSim as it is also realized for the horizontal winds??
gierschi@flightgear
 
Posts: 58
Joined: Tue Nov 03, 2015 10:40 pm

Re: Maximum possible lift??

Postby gierschi@flightgear » Tue Apr 19, 2016 8:49 am

No idea?
gierschi@flightgear
 
Posts: 58
Joined: Tue Nov 03, 2015 10:40 pm

Re: Maximum possible lift??

Postby Alant » Tue Apr 19, 2016 9:53 am

Lift is determined by the airflow over the aircraft. Flightgear imposes no limits on how this is calculated.

The important thing is that airspeed and ground speed are not the same thing. If the aircraft is flying north with an indicated airspeed of 100 kts, and the wind is coming from the north at 30 kts, then the ground speed would be 70 kts. The same applies to vertical gusts.

I think that you are confused unnecessarily
Alant
 
Posts: 1219
Joined: Wed Jun 23, 2010 6:58 am
Location: Portugal
Callsign: Tarnish99
Version: latest Git
OS: Windows 10/11

Re: Maximum possible lift??

Postby gierschi@flightgear » Tue Apr 19, 2016 1:52 pm

Thanks for the reply

You mean the True Airspeed instead of the indicated airspeed??

My second question asks for the sign of the mentioned properties:
The FG property ''/environment/wind-from-down-fps'' is positive when the wind is coming from down (a thermal/lift) and negative when you have a wind blowing in the direction of the ground. And simultaneously the properties ''/fdm/jsbsim/atmosphere/total-wind-down-fps'' and ''/fdm/jsbsim/atmosphere/turb-down-fps'' are negativ when the wind or turbulent portion is coming from down and positive when the wind blows in the direction of the ground?
gierschi@flightgear
 
Posts: 58
Joined: Tue Nov 03, 2015 10:40 pm

Re: Maximum possible lift??  

Postby Alant » Tue Apr 19, 2016 2:09 pm

It seems that the JSBSim ones are equal to, but opposite in sense, to the ones in environment. The clue is the inclusion of the word "from" in ''/environment/wind-from-down-fps''.

No doubt this has a historical origin as a North wind is one that comes from the North, but actually the air is travelling in a southerly direction.
Alant
 
Posts: 1219
Joined: Wed Jun 23, 2010 6:58 am
Location: Portugal
Callsign: Tarnish99
Version: latest Git
OS: Windows 10/11

Re: Maximum possible lift??

Postby Richard » Tue Apr 19, 2016 2:36 pm

gierschi@flightgear wrote in Tue Apr 19, 2016 1:52 pm:You mean the True Airspeed instead of the indicated airspeed


True Airspeed (TAS) and indicated airspeed (CAS) are different things again.

TAS is the speed of the aircraft relative to the outside air. https://en.wikipedia.org/wiki/True_airspeed

CAS is based on what instruments would read. https://en.wikipedia.org/wiki/Calibrated_airspeed

Ground Speed is the speed over the ground. If there is wind this will be reduced by the wind.
Richard
 
Posts: 810
Joined: Sun Nov 02, 2014 11:17 pm
Version: Git
OS: Win10


Return to Weather

Who is online

Users browsing this forum: No registered users and 3 guests