Potassium nitrate/sugar propellant improvement

We know that hexamine can not be oxidized with KNO₃ but with the additive phenolphthalein. My simple assumption was now that phenolphthalein could improve the combustion behavior of potassium nitrate/sugar  (sucrose, sorbitol etc.) as well, so I made a quick comparison test of 2g KNO₃/sucrose and 2g KNO₃/sucrose (65:35 ratio) with some phenlphthalein added:

The mixture with the added phenolphthalein was easier to ignite and burned much quicker. The melting points of sucrose (185–186 °C) and sorbitol (110–112 °C) are far lower than the melting point of phenolphthalein  (260 °C), so phenolphthalein and KNO₃ could be both dissolved in dry heated sugar.


Update August 29, 2011 

I just found a first source (The chemistry of fireworks by Michael S. Russell) where it is mentioned that phenolphthalein was used to enhance the burn rate of gun powder. Page 42: "...together with an organic fuel, known as phenolphthalein, which is said to enhance the burn rate."

I was not aware of this. I found the effect of phenolphthalein by myself without this knowledge.
Another source (Black Powder Manufacturing, Testing & Optimizing by Ian von Maltitz) says on page 27: "Phenolphthalein has been used as a charcoal substitute [for black powder]. Its use hasn't gone much beyond the experimental stage. This is possible because phenolphthalein is very expensive when compared to charcoal..."

Neither phenolphthalein and KNO₃ nor phenolphthalein and KClO₃ are combustible without a second fuel.