Angle of Attack is KING

bomber
Posts: 1379
Joined: Mon Nov 30, 2015 3:40 pm

Re: Angle of Attack is KING

Postby bomber » Sat May 28, 2016 8:17 am

jwocky wrote:Oh oh ohhhh, a bit careful here, please ...

1.) They go in and out ... obviously. Means, they change dynamically their relevance in lift and drag. Which leads to the effect that is is really dynamic ... as in, the flaps move from one position to the other. Now imagine you have all this in your main lift routine. Every function is internally worked as kind of a little chukn of software inherently blocking other parts of the software from getting to work while this thing runs. So you really want to split it up in smaller chunks.
Another example for such effects (not aerodynamically, but software-wise) is a JSB-fuel system. Looks quite nice on the paper and the theory is so elegant. And of course it runs faster in JSB than it would run in an extra.Nasal module ... however, the cost in blocking core cycles are higher



This seems to be the argument that a complicated flight model uses more processing power than a simple one and as such flight models not being that important we should have the less processing power one so that we can use the extra cycles on something else.

This is a flight modelling forum... I'm a flight modeller... and I'm never going to buy that argument.... afterall following that same premise 3d models should be restricted to 3000 vertexes and textures should be a maximum of 2 off 256x256

How about instead we see how much more detrimental to the output a complex flight model is to a simplistic...

As for tweaking.... nothing wrong with it, if it's your bag.... but there is more than one way of tweaking, you've learnt one method how about learning another ?

Simon
"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

User avatar
jwocky
Site Admin
Posts: 1833
Joined: Sat Sep 12, 2015 12:04 pm
Contact:

Re: Angle of Attack is KING

Postby jwocky » Sat May 28, 2016 11:05 pm

You got me wrong here, Bomber. I didn't say, FDM modelling is not important. What I said is, FDM modelling with keeping an eye on the software is even better.
If you pack everything in one monolithic function, you sit on one core with it and the whole monolith has to be worked through before anything else can happen. Alas, no part of FG, inclusind JSB actually supports multithreading, but what is in there, implicitly, is a number of yields, splitting as a side effect, long operations in slices. Which allows overall a better performance and a smoother operation over the whole system.
Free speech can never be achieved by dictatorial measures!

bomber
Posts: 1379
Joined: Mon Nov 30, 2015 3:40 pm

Re: Angle of Attack is KING

Postby bomber » Sun May 29, 2016 7:56 am

What does one function within fdm mean ?
"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
Posts: 1379
Joined: Mon Nov 30, 2015 3:40 pm

Re: Angle of Attack is KING

Postby bomber » Sun May 29, 2016 8:01 am

Here's my jsbsim flight model being pressure tested for performance issues within outerra.

https://youtu.be/jnL5KglQG_g
"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

User avatar
jwocky
Site Admin
Posts: 1833
Joined: Sat Sep 12, 2015 12:04 pm
Contact:

Re: Angle of Attack is KING

Postby jwocky » Sun May 29, 2016 8:42 am

one function providing an output value. Like a parameter for ground effect for example. One channel, one kinematic. The better the granularity of the source, the smoother things run in my experience and of course, if FG and JSB go multithreading at one point, you can profit from it easier if you worked already with a higher granularity.
Free speech can never be achieved by dictatorial measures!


Return to “JSBsim”

Who is online

Users browsing this forum: No registered users and 16 guests