Sugar Motor Formulation Performance
Significant differences are observed when one switches from one sugar fuel to another. These differences are most notable with respect to burn rates. Richard Nakka has compiled a useful spreadsheet (SRM) which can be used to input various sugar motor grain geometries and obtain motor performance as the output. Three fuels, sucrose, dextrose, and sorbitol are presently modeled by this spreadsheet in 65:35 KNO3/sugar ratios. The burn times for 38mm motors using these three fuels are 0.77 sec, 0.89 sec, and 1.13 sec respectively (at 1000 psi max. chamber pressure). The delivered ISP for each of these formulations is virtually identical at 132 to 134 sec. Thus, the nozzle throat area necessary for a given motor size will vary significantly from one sugar to another providing other parameters such as core diameter, additive use, etc. are held constant. The links below list static engine test data that have been obtained for each sugar fuel. Most of these tests were performed using 2 grain (Bates) 38 mm motors using Aerotech (or equivalent) T6 aluminum motor hardware and RCS phenolic/glass disposable nozzles. Each Bates grain is 46 mm long. Core diameters are 0.375". Test stand results were based on the use of an Aerocon 50kg load cell, amplifier, and DataQ data acquisition module. Note that these test stand results involve simple 65:35 mixtures of KNO3 and each respective sugar (except for the "mixtures" link below where surfactant is used as an additive). Test stand results of these formulations and other additives such as surfactants, iron oxides, etc. are located at the test stand link. Those links which have no test data will be populated once data is obtained. Who knows when that will occur.......
