Paraffin wax
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State: Paraffin wax is a solid at room temperature. It melts at a temperature of
46-68 degrees Celsius (115-154 degrees Fahrenheit).
Density: The density of paraffin wax is about 900 kilograms per cubic meter
(0.86 pounds per cubic foot).
Flash point: The flash point of paraffin wax is 199 degrees Celsius (388
degrees Fahrenheit). This means that it will ignite if it is exposed to an open
flame at or above this temperature.
Specific impulse: The specific impulse of paraffin wax is about 270 seconds
when used with liquid oxygen as an oxidizer. This means that it can produce
about 270 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: Paraffin wax is a relatively stable fuel and does not tend
to explode easily.
Ignition delay: The ignition delay of paraffin wax is about 0.1 seconds. This
means that it will ignite very quickly after it is exposed to an open flame.
Corrosiveness: Paraffin wax is not corrosive to most materials.
Toxicity: Paraffin wax is not toxic to humans or animals.
Acrylic polymer
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State: Acrylic polymer is a solid at room temperature. It melts at a temperature
of about 100 degrees Celsius (212 degrees Fahrenheit).
Density: The density of acrylic polymer is about 1,180 kilograms per cubic
meter (1.29 pounds per cubic foot).
Flash point: The flash point of acrylic polymer is about 38 degrees Celsius
(100 degrees Fahrenheit). This means that it will ignite if it is exposed to an
open flame at or above this temperature.
Specific impulse: The specific impulse of acrylic polymer is about 240
seconds when used with liquid oxygen as an oxidizer. This means that it can
produce about 240 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: Acrylic polymer is a relatively stable fuel and does not
tend to explode easily.
Ignition delay: The ignition delay of acrylic polymer is about 0.2 seconds. This
means that it will ignite slightly slower than paraffin wax after it is exposed to a
flame.
Corrosiveness: Acrylic polymer is not corrosive to most materials.
Toxicity: Acrylic polymer is not toxic to humans or animals.
Polyethylene
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State: Polyethylene is a solid at room temperature. It melts at a temperature
of about 110-130 degrees Celsius (230-266 degrees Fahrenheit).
Density: The density of polyethylene is about 950 kilograms per cubic meter
(0.91 pounds per cubic foot).
Flash point: The flash point of polyethylene is about 32 degrees Celsius (90
degrees Fahrenheit). This means that it will ignite if it is exposed to an open
flame at or above this temperature.
Specific impulse: The specific impulse of polyethylene is about 250 seconds
when used with liquid oxygen as an oxidizer. This means that it can produce
about 250 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: Polyethylene is a relatively stable fuel and does not tend
to explode easily.
Ignition delay: The ignition delay of polyethylene is about 0.3 seconds. This
means that it will ignite slightly slower than paraffin wax after it is exposed to a
flame.
Corrosiveness: Polyethylene is not corrosive to most materials.
Toxicity: Polyethylene is not toxic to humans or animals.
Poly(methyl methacrylate) (PMMA)
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State: PMMA is a solid at room temperature. It melts at a temperature of
about 105-108 degrees Celsius (221-224 degrees Fahrenheit).
Density: The density of PMMA is about 1,185 kilograms per cubic meter (1.29
pounds per cubic foot).
Flash point: The flash point of PMMA is about 32 degrees Celsius (90
degrees Fahrenheit). This means that it will ignite if it is exposed to an open
flame at or above this temperature.
Specific impulse: The specific impulse of PMMA is about 240 seconds when
used with liquid oxygen as an oxidizer. This means that it can produce about
240 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: PMMA is a relatively stable fuel and does not tend to
explode easily.
Ignition delay: The ignition delay of PMMA is about 0.2 seconds. This means
that it will ignite slightly slower than paraffin wax after it is exposed to a flame.
Corrosiveness: PMMA is not corrosive to most materials.
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Toxicity: PMMA is not toxic to humans or animals.
Hydroxyl-terminated polybutadiene (HTPB)
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State: HTPB is a solid at room temperature. It melts at a temperature of about
110-120 degrees Celsius (230-248 degrees Fahrenheit).
Density: The density of HTPB is about 1,050 kilograms per cubic meter (1.11
pounds per cubic foot).
Flash point: The flash point of HTPB is about 100 degrees Celsius (212
degrees Fahrenheit). This means that it will ignite if it is exposed to an open
flame at or above this temperature.
Specific impulse: The specific impulse of HTPB is about 270 seconds when
used with nitrous oxide as an oxidizer. This means that it can produce about
270 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: HTPB is a relatively stable fuel and does not tend to
explode easily.
Ignition delay: The ignition delay of HTPB is about 0.1 seconds. This means
that it will ignite very quickly after it is exposed to a flame.
Corrosiveness: HTPB is not corrosive to most materials.
Toxicity: HTPB is not toxic to humans or animals.
Hydrazine (N2H4)
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State: Hydrazine is a colorless, fuming liquid at room temperature. It has a
boiling point of 114 degrees Celsius (237 degrees Fahrenheit) and a freezing
point of 2 degrees Celsius (36 degrees Fahrenheit).
Density: The density of hydrazine is about 1.021 grams per cubic centimeter
(0.677 pounds per cubic foot).
Flash point: The flash point of hydrazine is 19 degrees Celsius (66 degrees
Fahrenheit). This means that it will ignite if it is exposed to an open flame at or
above this temperature.
Specific impulse: The specific impulse of hydrazine is about 288 seconds
when used with liquid oxygen as an oxidizer. This means that it can produce
about 288 Newtons of thrust for every kilogram of fuel that is burned.
Combustion stability: Hydrazine is a very stable fuel and does not tend to
explode easily.
Ignition delay: The ignition delay of hydrazine is about 0.002 seconds. This
means that it will ignite very quickly after it is exposed to a flame.
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Corrosiveness: Hydrazine is a corrosive fuel and can damage many materials.
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It is important to use materials that are resistant to hydrazine corrosion when
designing a hybrid rocket engine that uses hydrazine as a fuel.
Toxicity: Hydrazine is a highly toxic fuel and can be harmful to humans and
animals if it is inhaled or ingested. It is important to take precautions to avoid
exposure to hydrazine when handling it.
Overall, the best fuel for model rockets is a trade-off between safety, performance,
and ease of use. Paraffin wax is the safest and easiest to use, but it has the lowest
specific impulse and burn rate.
Acrylic polymer, polyethylene, and PMMA are all relatively safe and have higher
specific impulses than paraffin wax, but they can be more difficult to work with.
HTPB has a high specific impulse and burn rate, but it is more dangerous to handle.
Hydrazine has the highest specific impulse of any of these fuels, but it is also the
most dangerous.
If you are a beginner, paraffin wax is a good choice. If you are looking for more
performance, acrylic polymer, polyethylene, or PMMA are good options.
If you are an experienced model rocketeer and are looking for the best possible
performance, HTPB or hydrazine can be used. However, it is important to use these
fuels with caution and to follow all safety procedures.