The static tester is hooked up to a electronic pressure transducer (Ebay $12)
and sends data to an analog to digital converter to be read by a computer
This static tester gives the engine thrust over time. Plans for the static tester.
BAHAR - Propulsion
If you the website surfer, plans on getting into rockets and are
considering using ideas from this page, I warn you to be very careful!
When making rocket propellant a small spark or flame most likely
will ignite the propellant and you may be injured, killed or
explaining what you were doing to the fire department.
Accidents have a way of happening unless you are careful and know what you
are doing. My advice is start by researching how to use the various chemicals
to make propellant safely. After this, when you start making propellant safely,
start with very small batches of propellant to get an understanding for how it reacts.
The BAHAR project currently uses solid fuel for all propulsion.
If our rocket endeavors have continual success we will look into
hybrid and liquid engines as well as thrust vectoring but
for now solid motors seem to be the quickest way to get off the ground.
BAHAR Static Tester:
The static tester is hooked up to a electronic pressure transducer (Ebay $12)
and sends data to an analog to digital converter to be read by a computer
This static tester gives the engine thrust over time.
Plans for the static tester.
Motor I:
The first type of motor we experimented with consisted of fertilizer grade
potassium nitrate (KNO3) and icing sugar. By weight 65% KNO3 and 35% icing sugar were used.
To make a large amount of fuel at once we used a 25kg bag of KNO3 from a hydroponics store
which cost about $35. A garden store should be able to get this as well. A braun electric
coffee grinder that shoots the ground up KNO3 into a large garbage pail is helpful to grind the whole 25kg.
13.5 1kg bags of icing sugar then were dumped into the pail and lots of well ventilated, gloved hand
mixing is then required (at least 10 min - don't be lazy or your rockets will suck ;). I have now
heard that dextrose is better but icing sugar works fine for us and it doesn't need to be ground.
After you have this large amount of powder you can take a couple scoops out whenever you want and heat
it in a double boiler oil bath to melt it and squish it into your motor whenever you want.
These motors have an ISP of about 110 to 130 I believe.
The most important thing is to check out other websites that have much more detailed instructions
Richard Nakka's superb website.
Solid Motor II:
The second type of motor we made uses fertilizer grade ammonium nitrate (AN) instead of KNO3 as
the oxidizer. You can obtain this at the same places that sell KNO3 (it is used as fertilizer.
on golf-courses). We obtained a 25kg bag of this for about $40.
We are just in the starting phase of testing these engines. The main problems are
that AN burns slower than KNO3 so expensive metals are needed, like magnesium, to heat the motor and speed
up the rate of combustion.
A catalyst is also very helpful. Ammonium dichromate is apparently the best catalyst. Potassium dichromate can
also be used and may also be used to inhibit AN's phase changes, which can crack or expand fuel grains when the temperature changes.
This motor is held together with a rubber or plastic binder instead of the icing sugar motor which is held together
with the carmelized sugar.
Solid Motor III:
The third type of motor we have uses ammonium perchlorate as an oxidizer.
This oxidizer is expensive to purchase ($5US a lb) we are currently looking into making it ourselves.
Like the AN motor this motor is held together with a rubber or plastic binder.