MechJeb2

Hi,

I have been experiencing this problem for a very long time. I have never reported it before because I always manage to reduce the TWR at landing to something like 1.7-1.8 which seems more Mechjeb friendly.

The problem seems to be that Mechjeb is not taking into account the time it takes for an engine to produce thrust after the landing guidance begin to increase the vessel throttle (from idle).

I can attach demo video if it helps (I'm using RSS/RO)

From a development point of view I think this time can be measure empirically (in case it is not defined as part of the ModuleEngines), during launch or doing a quick burn test during landing.

Yes, exactly :)

I can confirm this will only happen with RealFuels/RealismOverhaul due to specific patches that change the way the throttling response works.

Is it because of such thing like useEngineResponseTime, engineAccelerationSpeed?

relevant bit of existing code that could get reused:

MechJeb2/MechJeb2/MechJebModuleThrustController.cs

Lines 301 to 311 in 63b2a02

    
           // Call this function to set the throttle for a burn with dV delta-V remaining. 
        
           // timeConstant controls how quickly we throttle down toward the end of the burn. 
        
           // This function is nice because it will correctly handle engine spool-up/down times. 
        
           public void ThrustForDV(double dV, double timeConstant) 
        
           { 
        
               timeConstant += vesselState.maxEngineResponseTime; 
        
               double spooldownDV = vesselState.currentThrustAccel * vesselState.maxEngineResponseTime; 
        
               double desiredAcceleration = (dV - spooldownDV) / timeConstant; 
        
               targetThrottle = Mathf.Clamp01((float)(desiredAcceleration / vesselState.maxThrustAccel)); 
        
           }

	// Call this function to set the throttle for a burn with dV delta-V remaining.
	// timeConstant controls how quickly we throttle down toward the end of the burn.
	// This function is nice because it will correctly handle engine spool-up/down times.
	public void ThrustForDV(double dV, double timeConstant)
	{
	timeConstant += vesselState.maxEngineResponseTime;
	double spooldownDV = vesselState.currentThrustAccel * vesselState.maxEngineResponseTime;
	double desiredAcceleration = (dV - spooldownDV) / timeConstant;

	targetThrottle = Mathf.Clamp01((float)(desiredAcceleration / vesselState.maxThrustAccel));
	}

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