Discussion Thrust building up with time

[N_Molson]

Hello, :hello:

To keep a rocket realistic, the thrust has to build up at liftoff during a few seconds, except maybe for SRBs.

I'm trying to get this piece of code working. With success sometimes, but not always. There's certainly a way to improve it.

The idea is that the engines are pre-ignited at 20%, then their thrust build up until it reaches 100%.

I tried to write it as a function. The basic concept is "équation de droites", I didn't found a translation on Wikipedia :


The following is running in clbkPostStep(double simt, double simdt, double mjd)

if (GetThrusterLevel(th_main[0]) >= 0.02 && GetThrusterLevel(th_main[1]) >= 0.02 && ignition1 && SEP == 0)
{
if (ignitionA) // timer
{
Time = simt;
}

long double MainE;
MainE = 0.2*(simt-Time) + 0.2; // y = a . x + b ; y = thrust level, x = time, b = "starting offset"

SetThrusterLevel(th_main[0], MainE);
SetThrusterLevel(th_main[1], MainE);

if (MainE >= 1)
{
ignition1 = false; // close loop
}

ignitionA = false; // do only once
}

So, what do you think about it ?

 

[Wishbone]

What would you like to hear?

MainE = ((simT-ignitionT)>threshold? 1.0 : 0.2+0.8*(simT-ignitionT)/threshold);

 

[N_Molson]

Just to see if there are simpler and more "stable" methods to do this, because mine seems a little unreliable...