Example: Lets say you have a C-6-7 engine the engine is twice a powerful than a B, and half as powerful than a D. The engine puts out 6 Newton�s of thrust per second. Since the delay is a 7 that means that there is a 7 second delay from the point of engine cutoff to ejection.
The liquid fuel rocket has two liquids that can be combusted. One is the oxidizer, and the other is the fuel. Some of the fuels need help to get ignited, and others will combust on contact.
The hybrid type motor some times has a solid fuel grain propellant, and is fed an oxidizer in the form of a gas, or liquid.
The space shuttle uses both solid, and liquid fuel engines. The large brown tank contains the liquid hydrogen, and liquid oxygenfor the three main engines of the orbitor. The white engines on the side of the main fuel tank are the solid fuel. Then there is the maneuvering rockets that are a special type of liquid engine, because the fuel will burn on contact which makes it more reliable, because it takes one more element of fireing the engine.
I have found that you can use the out side of a pen for multiple launch lugs. Just remove the inside of the pen, and cut off the other end of the pen. Then the pen can me cut into pieces for lugs.
The above rocket is PVC Rocket II EXP(you won't find this in stores). The rocket has been made from about 1'6" of PVC, glued to a 4 fin motor mount modified to take a D-12 engine. This has not been tested, awaiting test launch. Its earlier version PVC Rocket I EXP. had flown stable, but accelerated very slowly.
The are three rocket motors in the picture that are in the bottom left corner. The biggest motor is a D size motor, and the middle one is a A-B-C size motor, and the smallest motor is a half A motor.
Here is the post flight picture of the PVC Rocket II EXP. This rocket flew once(May 11, 2001). It had a successful ignition, and lift off. Parachute deployment was a failure, and the rocket smashed into the ground nose first. Smashed the nose cone, and misaligned the fin/motor mount. Plans for a PVC Rocket 3 are underway with a wide tube(so the parachute doesn't get jammed).
Here are some of my current working, model rockets not including my experiential built ones.
I have found that you can use the out side of a pen for multiple launch lugs. Just remove the inside of the pen, and cut off the other end of the pen. Then the pen can me cut into pieces for lugs.
Nose Cone:The nose cone can be made out of molded and solid plastic, wodden dowels shaped on a lathe, and anything that will fit the body tube, and it farily light.
Fuselage:This can be made out of fiber glass, carbon fiber, cardboard, construction paper rolled up, and even metal like aluminum.
It really depends on a couple of factory if you are building a small rocket for a A1/2 motor then you can get away with lighter materials and construction. If you are building a larger rocket you should only use materials that are going to be tough. One thing to keep in mind though of the fact of our hobbie, what goes up...must come down so be carful, and build safely.
Fins:Fins are usaly made from plastic, or balsa wood. Other woods can be used on heavier rockets like plywood, and base wood. Although thin metal can be used.
Launch Lugs:Most rockets use the launch logs like the ones that come in the model kids. I have been useing the outer shell of ballpoint pens cut down to size, or eyelets that screw into the fuselage.
Parachutes: You can use the parachutes that are sold in kits. If you want to build your own you can use material like Rip Stop Nylon, or trash bag material, or even silk, i think this is used in real parachutes im not sure).
