//-126
function DeOrbit{
	parameter burnLng, deltaV.

	lock pos to SHIP:geoposition.

	lock curLng to pos:lng.

	DECLARE LOCAL tgtLng IS burnLng - 5.
	if curLng > burnLng or curLng < tgtLng {
		SET WARPMODE TO "RAILS".
		SET WARP TO 3.
		print "warping to " + tgtLng.
		WAIT UNTIL curLng > tgtLng and curLng < burnLng.  
		SET WARP TO 0.
		print "arived at dst " + tgtLng.
		print "burn at " + burnLng.
	}
	print "currently at" + curLng.

	BRAKES ON.
	RCS ON.
	LOCK steering to retrograde.
	wait until curLng >= burnLng.

}

function CalculateBurnDuration{
	parameter dv.

	declare local isp is GetIsp().
	declare local finalMass is mass * exp(-dv / (isp * constant:g0)).
	declare local twr is ship:maxThrust / (((mass + finalMass)/2) * constant:g0).


	local t is dv / (twr * constant.g0).
	return t.
}

function GetIsp{
	LIST ENGINES IN allEngines.
	declare local totalThrust is ship:maxThrust.
	local sum is 0.
	local weights is 0.
	for eng in allEngines{
		if eng:IGNITION and not eng:flameout{
			local w is  eng:AVAILABLETHRUST / totalThrust.
			local ispW is eng:isp * w.
			set sum to sum + ispW.
			set weights to weights + w.
		}
	}
	return sum / weights.
}

// DeOrbit(-126, 250).
print CalculateBurnDuration(250).