Particle Emitting Speed Through Script

I have a JS which I try to change the velocity the particles are emitted. (I included full script for you to understand better)

#pragma strict

var engine: ParticleSystem;
var thrust: float;
var thrustRate: float;
var startThrust: float;
var fuel: float;
var F9: GameObject;

function Start () {
	engine = GetComponent.<ParticleSystem>();
	thrust = startThrust;
	fuel = 70;

function Update () {
	if(fuel > 0){
			if(100 > thrust){
				thrust = thrust + thrustRate;
			if(thrust > 0){
				thrust = thrust - thrustRate;
		fuel = fuel - (thrust * 0.000001);
		F9.GetComponent.<ParticleSystem>().Particle.velocity = thrust;

The problem is this part:
F9.GetComponent.().Particle.velocity = thrust;

Console tells me
"An instance of type ‘UnityEngine.ParticleSystem.Particle’ is required to access non static member ‘velocity’.

Like I said, I want the particles go faster as I increase “thrust”.

(If you ask why do I have sth called “engine”, it is bc I tried to use it as engine.Particles.velocity but it didn’t work)

ParticleSystem.Particle is a inner class.
what you want to adress is F9.GetComponent.<ParticleSystem>().startSpeed or velocityOverLifetime

you can see all the variables here: Unity - Scripting API: ParticleSystem