Burn Rate: 7.9 - 8.0 mm/s

Despite the stabilizer it is still quite a sensitive composition. It should be pressed, not rammed, into tubes.

Some say drying on paper causes too much of the stabilizer to be wicked out and lost leaving an overly sensitive composition, but I haven't experienced this problem in practice. However I use kitchen wrap rather than kraft which tends to be more 'hairy' and absorbent.

It is quite a good nozzleless rocket propellant, a short core (about 2-3 IDs of the case long) is useful, but too large and the rocket will explode.

Try to achieve a completely homogeneous composition for best performance. If there are any white flakes visible re-wet with solvent and rub through a screen over and over until is it completely, consistently, pink.

More petroleum jelly can be used if you experience unresolvable explosions, try 5 parts. Sodium Benzoate can replace the Sodium Salicylate one-for-one for a somewhat less powerful composition.

Potassium Salicylate is a less hygroscopic replacement for the Sodium version but is much harder to source.

Copper Salicylate can be used to achieve pale-blue tailed rockets but they won't whistle. The Copper Salicylate has to be very dry, and keeping it that way is a challenge.

A few percent Titanium flake can be added for white sparks. Note however that adding Titanium or other metals sensitizes the composition significantly. It is very unwise to sieve a metal containing whistle composition! Prepare the whistle first and sieve it well then mix in the metal by diapering. Do so in small quantities for best safety.

Method:

Pre-screen the Potassium Perchlorate several times. Screen the Iron Oxide and Sodium Salicylate together well.

Dissolve Petroleum Jelly in a small quantity of Petroleum Spirits (or other suitable solvent) warming gently on a water bath, dilute sufficiently to allow full wetting the combined quantity of composition.

Mix solution with Sodium Salicylate and Iron Oxide mixture and stir to wet completely. Add Potassium Perchlorate and mix very well, adding extra solvent if required.

Force through a sieve at least five times to achieve a completely homogeneous pink dough. Use a waterbath if required to drive off excess solvent and achieve a crumbly consistency, screen again and spread out on paper to allow the solvent to evaporate completely.