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{"sheet":"Introduction","index":0,"n_rows":52,"n_cols":9,"rows_kept":52,"cut":false,"hidden":false,"merged":[],"flags":["formulas_cached_only"]}
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[]
[]
[null,"IGNITER.XLS",null,"MS EXCEL 2000 Spreadsheet",null,null,null,"Written by R.Nakka Oct..1999, Release 1.00"]
[{"$nulls":7},"Parachute addition by D. Pennington, Mar. 2002"]
[{"$nulls":7},"Latest Release 1.1"]
[null,"Introduction",{"$nulls":5},"For free distribution"]
[]
[null,"This spreadsheet may be used to estimate rocket motor chamber pressure, or parachute chamber"]
[null,"pressure that results from the combustion of a pyrotechnic igniter charge."]
[null,"The igniter charge is typically Black Powder (BP), although this spreadsheet may be"]
[null,"used for any pyrotechnic mixture, as long as the charge mass density and  impetus*  is known."]
[]
[]
[null,"Values for impetus for a few mixtures are given in Table 1."]
[null,"For BP,  the mass density may be determined using the BP worksheet. Either mass ratios or"]
[null,"volumetric ratios of potassium nitrate (KN), sulphur (S) or charcoal (Ch) may be used as input."]
[]
[null,"Rather than inputting igniter charge mass, the igniter volume is required, from which the mass"]
[null,"is calculated based upon the density. This would seem to be a more useful approach, as "]
[null,"the volume occupied by an igniter is often a limiting design parameter."]
[]
[null,"The method is based on the NASA report SP-8051 Solid Rocket Motor Igniters,and"]
[null,"makes the reasonable assumption that the products of combustion behave as an ideal gas,"]
[null,"with the ideal gas equation (PV=mRT) being applicable. Combustion is assumed to be"]
[null,"complete and adiabatic, with the assumed combustion time being brief, such that no"]
[null,"pressure loss (e.g. through the nozzle throat) occurs."]
[]
[]
[null,null,"Table 1"]
[null,null,"Material",null,"Grade",null," Impetus (ft-lbf/lbm)"]
[null,null,"Black Powder",null,"Igniter (note 1)",null,"100 000",null,"Note 1"]
[null,null,"Black Powder",null,"Commercial FFFF",null,"85 000",null,"Note 2"]
[null,null,"Black Powder",null,"User prepared",null,"50 000 - 70 000",null,"Note 3"]
[null,null,"KN-Sucrose powder",null,"User prepared",null,"110 000",null,"Note 4"]
[]
[]
[null,"* Impetus is  represented by the term RT  in the ideal gas equation, where R is the"]
[null,"gas constant, and T is the combustion temperature."]
[null,"Impetus of a propellant or pyrotechnic mixture represents available energy per unit mass."]
[null,"This may be determined for any pyrotechnic mixture by use of a chemical equilibrium"]
[null,"program such as one of the PEP programs (PROPEP, GUIPEP, CET, etc.)"]
[]
[]
[]
[null,"Notes:","1. This value is taken from NASA SP-8051, Section 2.1.4. (seems high)."]
[null,null,"2. Calculated, based on KN/Ch/S ratio of 74/15.6/10.4"]
[null,null,"    using GUIPEP."]
[null,null,"3. Estimated"]
[null,null,"4. Calculated, KN/Sucrose ratio of 65/35, using GUIPEP.  This mixture is"]
[null,null,"    energetic, but requires generous heat input to initiate. An exploding"]
[null,null,"    bridgewire (EBW) initiator may be more suitable than a resistive element."]

{"sheet":"Pressure calc","index":1,"n_rows":55,"n_cols":14,"rows_kept":55,"cut":false,"hidden":false,"merged":[],"flags":["formulas_cached_only"]}
[]
[null,"CHAMBER PRESSURE CALCULATION"]
[]
[]
[null,"Instructions:"]
[null,null,"1)","Choose igniter charge material by putting an 'X' in appropriate box (use Delete key to remove existing 'X')."]
[null,null,null,"If Black powder is selected, the density cell will be automatically filled in (the density is read from"]
[null,null,null,"the BP worksheet). If Other is chosen, enter the value of mass density."]
[]
[null,null,"2)","Fill in the remaining shaded cells with required data."]
[null,null,null,"Pressure in the motor chamber with G=1 must never exceed the MEOP"]
[null,null,null,"(Maximum Expected Operating Pressure) of the motor. Pressure in parachute chamber should not exceed fail pressure"]
[null,null,null,"of body tubing being used (e.g. fibreglass, plastic, cardboard, phenolic etc.)"]
[]
[null,null,"3)","If being used to calculate ejection pressures and ejection force for parachutes, component separation charges etc.,"]
[null,null,null,"then Vc becomes the volume of the chamber in which the charge is being placed (e.g. parachute compartment) See also"]
[null,null,null,"Note [b]."]
[]
[]
[]
[null,"Igniter charge material"]
[]
[null,"X","  Black powder",null,0.03173485276254163,"lbm/in3","density of BP charge   (see BP worksheet...)"]
[null,null,"  Other",null,null,"lbm/in3","density of  igniter charge powder"]
[]
[null," Chamber Pressure calculation",{"$nulls":7}," Ejection Force calculation for parachutes etc."]
[]
[null,null,"Vic =",0.098,"in3","Volume of igniter charge    NOTE [1]",null,null,null," Internal diameter rocket tube *",null,null,2.52,"in"]
[null,null,"Vc =",14,"in3","Volume of  motor chamber, empty"]
[null,null,"Vg =",10,"in3 NOTE [b]","Volume of propellant grain",null,null,null," Calculated force of ejection",null,null,4128.089555406696,"lb force"]
[]
[null,null,"C =",0.0031100155707290797,"lbm","Mass of igniter charge   ",null,null,null,"  Notes:"]
[null,null,"=",1.4107030628827106,"grams",{"$nulls":4},"[a]","* Assumes chamber closed by fore and aft"]
[null,null,"V =",4,"in3","Motor chamber free volume",{"$nulls":4},"bulkheads same diameter as ID of rocket."]
[null,null,"l =",85000,"ft-lbf/lbm","Impetus of charge powder     NOTE [2]",null,null,null,"[b]","Vg for parachute compartments etc. is either"]
[null,null,"D =",0.0007775038926822699,"lbm/in3","Loading density (C/V)",{"$nulls":4},"zero, or, if volume of parachute, cords, wadding,"]
[null,null,"Pa =",14.7,"psia","Ambient (atmospheric) pressure",{"$nulls":4},"etc. is known, that total value in cu. in."]
[null,null,"G =",1,null,"Fraction of original charge mass "]
[{"$nulls":5},"consumed [NOTE 3]"]
[null,null,"P =",827.6717791244648,"psia","Pressure in motor chamber"]
[]
[]
[]
[null,null,"Notes:"]
[]
[null,null,"[1]  The volume of a cylindrical tube type igniter may be readily calculated here:"]
[]
[null,null,"D =",0.25,"in.","Inside diameter of tube"]
[null,null,"Lic =",2,"in.","Charge length"]
[null,null,"Vic =",0.09817477042468103,"in3","Volume of igniter charge"]
[]
[null,null,"[2]   The impetus (or effective force) delivered by a particular charge material "]
[null,null,"       See Table 1 for some values of impetus."]
[]
[null,null,"[3]   Normally use G=1. The calculated pressure is then the maximum."]

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[]
[null,"BLACK POWDER DENSITY CALCULATOR"]
[]
[null,null,"Instructions:"]
[null,null,"1)","Enter BP composition  by either  a) mass, or b) volume , in appropriate set of cells.   NOTE [1]"]
[null,null,null,"The alternative set of cells must be blank  (use Delete key)."]
[]
[null,null,"2)","Enter loading fraction."]
[]
[]
[null,null,"a) Composition by mass",null,null,null,"b) Composition by volume"]
[null,null,null,"(percent)",null,null,null,"(percent)",null,null,"by mass"]
[{"$nulls":10},"(calculated)"]
[null,null,"KN",74,"%",null,"KN",null,"%","","","",null,74]
[null,null,"Charcoal",16,"%","or","Charcoal",null,"%","","","",null,16]
[null,null,"Sulphur",10,"%",null,"Sulphur",null,"%","","","",null,10]
[null,null,null,"","D"]
[]
[null,"->","Calculated ideal density of  BP composition     NOTE [2]"]
[]
[null,null,1.4653451806247801,"g/cm3"]
[]
[]
[null,null,"Loading fraction (ratio of actual BP density to ideal density)"]
[]
[null,null,0.6]
[]
[null,"->","Calculated  actual density of  BP composition"]
[]
[null,null,0.879207108374868,"g/cm3"]
[null,null,0.03173485276254163,"lbm/in3"]
[]
[]
[null,null,"Notes:"]
[]
[null,null,"[1]  Typical  composition is  KN 74%, Charcoal 16%, Sulphur 10%, by mass."]
[]
[null,null,"[2]  Based on ideal densities of constituents:"]
[null,null,"      (Ref. CRC Hdbk. of Chemistry & Physics, 54th ed.)"]
[null,null,null,"KN",2.11,"g/cm3",null,null,0]
[null,null,null,"Charcoal",0.57,"g/cm3",null,null,0]
[null,null,null,"Sulphur",1.96,"g/cm3",null,null,0]
[{"$nulls":8},0]

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[]
[]
["EQUATIONS USED IN THE SPREADSHEET"]
[]
["Pressure calc worksheet",null,null,null,"BP worksheet"]

{"sheet":"Revisions","index":4,"n_rows":13,"n_cols":5,"rows_kept":13,"cut":false,"hidden":false,"merged":[],"flags":["formulas_cached_only"]}
[]
[]
[]
[]
[null,"Revision Record"]
[]
[]
[null,"Revision","Date","Worksheet","Changes"]
[]
[null,1,"1999-04-01","-","(initial release)"]
[null,1.1,"2002-03-01","Pressure calc","parachute modification (DGP)"]
[null,null,null,"Introduction","Text modified"]
[null,null,null,"BP","Added 'pop up' comment"]