KNSB Motors

Potassium Nitrate / Sorbitol

KNSB (Potassium Nitrate and Sorbitol) motors are my favorite of the "sugar" motors for a few reasons. It has many benefits over than standard sucrose (KNSU) propellant in that:

  1. Lower melting temperature (~203°F) - This means that you can cook your fuel at a lower overall temperature, increasing safety of both yourself and the propellant from its flash point as well as a much longer working time.
  2. No carmelization - You wont have to worry about "burning" another batch from overcooking.
  3. Longer Burn Time - Burn rate is decreased.
  4. Lower Hygroscopicity - Grains will not deteriorate as fast and storage is simplified.
  5. Less Viscous - You can pour motor grains much easier than sucrose propellants.
  6. Quicker/Easier - It cooks both faster and easier than sucrose.

There are a few drawbacks as well, but I feel they are easily overweighed by the benefits. Still, they should be noted:

  1. More Expensive - Sorbitol is about 5-10 times more expensive than sugar (depends on order size and place)
  2. Lower Performance - Sorbitol has a very similar performance to KNSU but it is lower (on the range of just a percent or two, depending on your techniques of making and packing the propellant).
  3. Odd Thrust Curve - KNSB sometimes displays triangular thrust curves. For more information on this, please visit Richard Nakka's site.