So here it is. After much thought and elbow grease the Silverlite was launched.
I had two unsatisfactory behavior from this launch.
The first one being the launch rod not firmly secured to the ground. This allowed the rocket to tilt and took off at an angle. I'm also going to make sure my launch lugs are secured and are not flimsy.
Fuel also chuffed. The fuel had some moisture in it and combined with my low kn ratio it was a bit harder to ignite.
Friday, July 22, 2011
Thursday, July 7, 2011
Welcome to my blog
I assure you, my reader, that I'm not an expert. I'm an amateur rocket builder. When I was about 6 years old, my uncle tried to make a rocket. He was using home made black powder stuffed in a toothpaste tube. It flew a whopping 1 foot.....and I never forget it!
How I Started
I started making my own rockets about January of 2011. Since then I've flown so many stick rockets that I lost count.
Fuel
Basically all of my rockets use potassium nitrate as oxidizer and a sugar fuel.
Common sugars are Sucrose (White table sugar), Dextrose (or glucose), and Fructose.
Basically I made my first rockets using 65g of potassium nitrate and 35g of Sucrose.
That is 100g of fuel. Typically that is the ratio I use. 65/35 % of KNO3 and SUcrose.
I prepared the fuel with a method found on James Yawn's site called the recrystallization method. You can find it here and another video here.
One problem with sucrose is that it is very brittle and can crack easily causing your fuel to have more burning surface area and thus produces more pressure which can lead to an explosion which gives you a CATO (catastrophic at takeoff).
James use Karo syrup and dextrose to reduce this flaw.
Stick rockets are easy to make. You can learn by following the method used in this video:
Nice, right?
Their center of pressure (CP) and center of gravity (CG) is balanced by the weight of the motor and the body of the stick. I made them just like that with the exception of the material for nozzle and bulkhead. They used kitty litter, or bentonite clay. I do not have any of that so i used the soil in my location which is a red type of clay. You can try the soil where you live as long as it is clay based and not sand.
Then, I graduated from sticks
I've made those type of rockets until I started making bigger motors. Pretty soon I found myself using 1 inch schedule 40 PVC packed and cored with 6 inches of fuel. That was when I realized it was too big, too heavy, unsafe to be sending it up on stick with no parachute for a safe landing. My main concern was landing on someone's car or on their roof!
Here is a 4 inch stick rocket (black powder) that i'm still very proud of
For smaller rockets it would be safe but not for anything that heavy (car windshield smashed by falling object?).
Model Rockets
Rockets with fins and nose cones (traditional looking ones) require more than just a stick to fly. They are a little more difficult to fly because you have to balance the center of pressure and center of gravity. Basically to get your rocket flying your CP must be behind your CG by at least 1 caliber (cal). The thickness of the airframe is 1 cal.
And here is my first awful flight with a fin based motor. No parachute as yet.
One VERY important device was missing from these launches - the electric igniter. Igniters are more reliable and they give you all the power at ignition. Visco fuses waste some fuel before the rocket takes off; this was evident in the videos above. Ignitors also give you a safe distance to launch your rocket.
Rocket Design
In order to design and launch successfully, you will need some software to assist you. Rocksim is expensive but is often mentioned in rocketry groups for its reliability (paid software - developers are more responsible). I use Open Rocket. It is free and also supports ENG files that i export from My Free ENG software. Burnsim can be used. It is not free but it is worth the price.
I design motors in SRM, test them, and then when I'm satisfied with that I export the ENG to OpenRocket.
I then design a rocket around this motor in Open Rocket. Voila, you now have a rocket to build spec by spec!
the Silverlite rocket consists of the following materials:
Motor:
- 1 inch schedule 40PVC motor, 6 inches core fuel length, 0.48inch core, 0.375 nozzle throat, 0.83 exit.
Airframe
- 1.5 inch pvc drainpipe. The thin one that can be cut with strong scissors.
Fins
Solitex - a really thin board used in ceilings. Any thin strong hardwood can be used.
Nosecone
Same PVC tubing as the airframe cut to form the nose. A method I adopted from Ed Weber.
Recovery
My recovery method is based on a method developed by Ed Weber (http://youtube.com/rocketmanbkk)
How I Started
I started making my own rockets about January of 2011. Since then I've flown so many stick rockets that I lost count.
Fig 1.0 Typical stick tailed rocket (from http://warandgame.com/)
Fuel
Basically all of my rockets use potassium nitrate as oxidizer and a sugar fuel.
Common sugars are Sucrose (White table sugar), Dextrose (or glucose), and Fructose.
New
Honey is also used for its fructose.
Basically I made my first rockets using 65g of potassium nitrate and 35g of Sucrose.
That is 100g of fuel. Typically that is the ratio I use. 65/35 % of KNO3 and SUcrose.
I prepared the fuel with a method found on James Yawn's site called the recrystallization method. You can find it here and another video here.
One problem with sucrose is that it is very brittle and can crack easily causing your fuel to have more burning surface area and thus produces more pressure which can lead to an explosion which gives you a CATO (catastrophic at takeoff).
James use Karo syrup and dextrose to reduce this flaw.
Stick rockets are easy to make. You can learn by following the method used in this video:
Nice, right?
Their center of pressure (CP) and center of gravity (CG) is balanced by the weight of the motor and the body of the stick. I made them just like that with the exception of the material for nozzle and bulkhead. They used kitty litter, or bentonite clay. I do not have any of that so i used the soil in my location which is a red type of clay. You can try the soil where you live as long as it is clay based and not sand.
Then, I graduated from sticks
I've made those type of rockets until I started making bigger motors. Pretty soon I found myself using 1 inch schedule 40 PVC packed and cored with 6 inches of fuel. That was when I realized it was too big, too heavy, unsafe to be sending it up on stick with no parachute for a safe landing. My main concern was landing on someone's car or on their roof!
Here is a 4 inch stick rocket (black powder) that i'm still very proud of
For smaller rockets it would be safe but not for anything that heavy (car windshield smashed by falling object?).
Model Rockets
Rockets with fins and nose cones (traditional looking ones) require more than just a stick to fly. They are a little more difficult to fly because you have to balance the center of pressure and center of gravity. Basically to get your rocket flying your CP must be behind your CG by at least 1 caliber (cal). The thickness of the airframe is 1 cal.
And here is my first awful flight with a fin based motor. No parachute as yet.
Launched near that abandoned house. Do NOT do that with your launches.
Launch in open field instead.
And then the "yellow mellow"
One VERY important device was missing from these launches - the electric igniter. Igniters are more reliable and they give you all the power at ignition. Visco fuses waste some fuel before the rocket takes off; this was evident in the videos above. Ignitors also give you a safe distance to launch your rocket.
Rocket Design
In order to design and launch successfully, you will need some software to assist you. Rocksim is expensive but is often mentioned in rocketry groups for its reliability (paid software - developers are more responsible). I use Open Rocket. It is free and also supports ENG files that i export from My Free ENG software. Burnsim can be used. It is not free but it is worth the price.
I design motors in SRM, test them, and then when I'm satisfied with that I export the ENG to OpenRocket.
I then design a rocket around this motor in Open Rocket. Voila, you now have a rocket to build spec by spec!
My Silverlite Rocket (under construction as we speak)
the Silverlite rocket consists of the following materials:
Motor:
- 1 inch schedule 40PVC motor, 6 inches core fuel length, 0.48inch core, 0.375 nozzle throat, 0.83 exit.
Airframe
- 1.5 inch pvc drainpipe. The thin one that can be cut with strong scissors.
Fins
Solitex - a really thin board used in ceilings. Any thin strong hardwood can be used.
Nosecone
Same PVC tubing as the airframe cut to form the nose. A method I adopted from Ed Weber.
Recovery
My recovery method is based on a method developed by Ed Weber (http://youtube.com/rocketmanbkk)
- Umbrella made into a parachute.
- Wooden plunger for ejecting the parachute
- Waist band elastic used for pushing the plunger at the right time, for the ejection.
(click to enlarge)
 Simulations done with different motor designs. (click to enlarge) |
(work in progress)
|
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