Propellants:

The primary oxidizer for this project will be hydrogen peroxide. Hydrogen peroxide was used in rocket applications mainly from 1938 to 1965 as a monopropellant as well as a bipropellant, but is no longer widely used because of its storage stability problem. Typically the hydrogen peroxide used for rockets was in a highly concentrated form of 70% to 99%, this concentrated form is also known as t-stoff. T-stoff was used as the oxidizer in many of the german rockets built during world war II, typically at a concentration of 80% hydrogen peroxide, 20% water with added stabilizers such as Phosphoric acid, Sodium phosphate, an 8-Oxyquinoline. Even with the added stabilizers, t-stoff will slowly decompose during long storage periods and the oxygen will bubble out of the liquid leaving water. If it has been contaminated it will decompose at a faster rate and has the potential to become very explosive. concentrated hydrogen peroxide is also hazardous to handle, it may cause severe burns when in contact with skin and there are many organic materials that may react exothermically with it and cause fires. Hydrogen peroxide is also photochemically sensitive, thus decomposition can be triggered by exposure to electromagnetic energy, the general decomposition in this case is as follows.

In the combustion chamber hydrogen peroxide will decompose according to the chemical reaction below. The products of the decomposition are superheated steam and gaseous oxygen.

To accelerate the decomposition process a catalyst such as various permanganates, manganese dioxide, platinum, and iron oxides can be used although any impurity can act as a catalyst. The reaction is completely heterogeneous up to about 400°C, and may be partly homogeneous above 425°C. The activation energy is about 8.5-19.0 kcal/mole at low temperatures and 40-50 kcal/mole at high temperatures. One advantage to using hydrogen peroxide in this system is its ability to act as an oxidizing and reducing agent. The solid propellant will be a form of permanganate, so combustion will be supported by the decomposition of hydrogen peroxide and reduction of permanganate. Although the system is designed to support the use of t-stoff, it is expensive, so 50% hydrogen peroxide will be substituted. The reactions are the same, but the power and efficiencies of the engine will be penalized.

The reaction in the combustion chamber should involve the following overall sequence. When hydrogen peroxide decomposes the first step will be the rupture of the oxygen bonds, thus

forming hydroxide. With the introduction of hydroxide, the hydrogen peroxide becomes unstable and is further reduced by the chain reaction:

The solid fuel grains for this project will be potassium permanganate. The permanganate will act as a catalyst for the decomposition of hydrogen peroxide. It will also act as an oxidizer when reduced by the portion of hydrogen peroxide that does not decompose. In general the permanganate will reduce according to the following reaction.

We can see that again one of the products is hydroxide, thus further promoting the decomposition of hydrogen peroxide. The reactions are exothermic but not extremely violent and will flood the chamber with warm oxygen. Thus, all that is needed is a spark or open flame inside the chamber to accelerate the reactions and complete the combustion process. Once the oxygen has been ignited the combustion process within the chamber will continue until the fuel has been depleted. From the above reactions the exhaust products should be potassium, manganese dioxide, hydroxide, and steam with some granules of unreacted potassium permanganate that may get blasted out of the chamber. So, the general reaction should be similar to:

Mixture Ratios:
Using the chemical reactions above, the mixture ratios for complete combustion can be estimated. Complete combustion occurs when there is no leftover fuel or oxidizer in the chamber at engine burn out. The mixture ratio, also known as the stoichiometric ratio, will mainly depend on the types of propellants. Although the stoichiometric ratio reveals the theoretical maximum temperatures and heat release, in most rocket engines the optimun conditions occur at ratios other than the stoichiometric ratio. Because of this, we can only use the calculated values to estimate a mixture ratio at which to start the experimental investigations. The optimum mixture ratio may also be affected by the stay time within the combustion chamber and the cooling system, if any. Once the optimum mixture ratio has been established, any deviations will result in penalties in engine performance.


Properties of Hydrogen Peroxide:

Typical Physical Properties of Hydrogen Peroxide
Molecular weight	34.016
Density of solid at freezing point	1.71	g/cc
Density of liquid at 20°C	1.450	g/cc
Viscosity of liquid at 20°C	1.245	cwntipoises
Viscosity of vapor at the boiling point	137	micropoises
Surface tension at 20°C	80	dynes/cm
Diffusivity in air at 60°C	0.188	cm2/sec
Heat of sublimation at the freezing point	15.58	kcal/mole
Melting point	-0.43	°C
heat of fusion at the melting point	2987	cal/mole
Boiling point	150.2	°C
Heat of vaporization	12.33	kcal/mole
Critical temperature	457	°C
Critical pressure	214	atm
Heat capacity of solid at the freezing point	0.39	cal/g °C
Heat capacity of liquid	0.628	cal/g °C
Heat capacity of vapor	10.22	cal/g °C
Heat of formation in vapor	-32.52	kcal/mole
Free energy of formation in vapor	-25.24	kcal/mole
Dielectric constant at 20°C	73.1
Magnetic susceptibility	-0.50	10^6 cgs emu/g
Refractive index	1.4067

Thermodynamic Functions of Hydrogen Peroxide at 1 ATM
	-((F°-Ho°)/T)	(H°-Ho°)/T	S°	Cp°	H°-Ho°
Temperature (°K)	cal/deg mole	cal/deg mole	cal/deg mole	cal/deg mole	cal/mole
298.16	46.33	9.42	55.76	11.00	2810
300	46.39	9.43	55.82	11.02	2830
350	47.87	9.69	57.54	11.47	3391
400	49.17	9.94	59.11	11.93	3976
500	51.44	10.42	61.84	12.68	5210
600	53.38	10.85	64.23	13.28	6511
700	55.09	11.21	66.31	13.76	7848
800	56.61	11.58	68.17	14.15	9263
900	57.99	11.89	69.86	14.51	10702
1000	59.26	12.15	71.40	14.84	12153
1100	60.43	12.41	72.83	15.15	13656
1200	61.56	12.65	74.17	15.45	15186
1300	62.52	12.87	75.41	15.72	16737
1400	63.50	13.09	76.58	15.97	18322
1500	64.41	13.29	77.69	16.20	19935
Cp° = constant pressure heat capacity F° = free energy Ho° = enthalpy at absolute zero H° = enthalpy of H2O2 as ideal gas at 1 atmosphere S° = Entropy T = absolute temperature