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Clean up and improve node execution code.

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This commit is contained in:
Anna Rose Wiggins 2021-08-03 20:35:50 -04:00
parent 935c6cf671
commit cadd3404b9
3 changed files with 89 additions and 117 deletions
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98
lib/throttle.ks
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@ -19,101 +19,3 @@ function TWR {
local t is THROTTLE * SHIP:AVAILABLETHRUST.
return t/(m*G).
}
// Calculate the time required to burn a given dV at a given altitude.
// Must be called while in the same SOI as the burn itself.
// Assumes a perfectly spherical Kerbal in a vacuum.
function BurnTime {
parameter dV, m is SHIP:MASS, s is STAGE:NUMBER.
local f is stageThrust(). // Engine Thrust (kg * m/s²)
local Isp is stageISP(). // Engine ISP (s)
local dVs is SHIP:StageDeltaV(s):VACUUM.
if dV > dVs {
// TODO: not 100% this is needed vs using DeltaV:DURATION.
// Docs suggest DeltaV:DURATION is not entirely reliable, however.
// For now we're logging both values for comparison.
local t is burnTimeCalc(dVs, m, Isp, f).
// debug
print "Computed stage burn time = " + t.
print "KSC-estimated stage burn time = " + SHIP:StageDeltaV(s):DURATION.
// end debug
local parts is list().
for part in parts {
if part:DECOUPLEDIN = s - 1 {
set m to m - part:MASS.
}
}
return t + BurnTime(dV - SHIP:STAGEDELTAV(s):VACUUM, m, s - 1).
}
// debug
local t is burnTimeCalc(dV, m, Isp, f).
print "Burn time in last utilized stage = " + t.
// end debug
return t.
}
// Convenience function to wrap the actual calculation for burn time.
function burnTimeCalc {
parameter dV, m, Isp, f.
if f = 0 {
print "WARNING: Tried to calculate burn time with a thrust of 0. Returning 0. Your calculations are probably wrong.".
return 0.
}
// TODO: this formula differs from the following:
// t = ((M0 - Mf) * Isp * G) / f
// which is suggested at https://www.reddit.com/r/Kos/comments/lev9pw/getting_burntime_from_next_stage/gmig0hl/?context=8&depth=9
// are they equivalent? Is one better than the other? This one doesn't require
// knowing final mass, which is nice.
local g0 is CONSTANT:G0.
return g0 * m * Isp * (1 - CONSTANT():E^(-dV/(g0*Isp))) / f.
}
// Calculate the ISP for a given stage.
// Defaults to current stage. Assumes your ship is designed so that
// engines are discarded immediately when they flame out.
function stageISP {
parameter s is STAGE:NUMBER.
local en is list().
list ENGINES in en.
local ispSum is 0.
local eCount is 0.
for e in en {
if e:STAGE = s or e:STAGE > s and e:DECOUPLEDIN < s {
set ispSum to ispSum + e:ISP.
set eCount to eCount + 1.
}
}
if eCount = 0 { return 0. }
return ispSum / eCount.
}
// Calculates the total thrust for the given stage, in kN.
// Defaults to current stage. Assumes your ship is designed so that
// engines are discarded immediately when they flame out.
function stageThrust {
parameter s is STAGE:NUMBER.
local en is list().
list ENGINES in en.
local sum is 0.
for e in en {
if e:STAGE = s or e:STAGE > s and e:DECOUPLEDIN < s {
set sum to sum + e:POSSIBLETHRUST.
}
}
return sum.
}