Project
Ignis engine.

Construction

• This rocket was built to flight test a cluster of four Ignis engines. The rocket has a maximum total thrust of 200 lbs. with a burn time of 3.5 seconds. The engines are located 30" forward of the rear of the rocket due to their weight of 14.69 lbs. (8.0 lbs. of which is fuel). The rocket body is vented aft of the engines to allow the exhaust gasses to exit the rocket body without causing a vacuum. The rocket body is made from 6" cellular ABS drain pipe. Fins are constructed from 1/4" balsa wood with poster board laminated on either side to increase their strength. Fins are held on with 10-24 fully threaded aluminum studs. Each engine has two igniters for redundancy. igniters will be set off with a 120 volt, 20 amp circuit via a portable generator, this will ensure the ignition of all four engines at the same time. The rocket carries a 22 second smoke charge that will serve as a delay element for the parachute deployment device. It will also serve to indicate the rockets position up until parachute ejection. The nosecone is made from plaster and gauze; its hollow shell will house the smoke charge and ejection charge as well as the parachute and ropes.
• Rocket body weight without fins or nosecone: 7.09 lbs.
• Engine weight: 14.69 lbs.
• Fuel weight: 8.00 lbs.
• Total take-off weight: 28.50 lbs.
• Thrust to weight ratio: 7:1
• Rocket length: 72"
• Rocket diameter: 6.5"
• Center of gravity: 34" from nose.
• Center of pressure: 45.5" from nose.
• Stability: 1.76

Pros

• Rocket was inexpensive and easy to construct.
• Rocket is scaleable for larger engines and a video bay.

Cons

• The four bolts that hold the engine cluster in the rocket body have a tendency to pull on one side of the engine casing allowing for a possible structural failure of the end cap. Future designs will have two rods for the engine cluster to hang from.
• The two wires that go up the smoke tube to the igniter do not get blown out when the smoke charge is lit. It is possible that this could cause a blockage of the smoke discharge tube leading to an overpressurazation of the smoke charge casing and eventually an explosion. Future designs will incorporate smaller gauge wire that is routed through the side of the smoke charge casing which will not block the smoke discharge tube.
• There is too much resistance in the igniters. The generator failed to light all four engine sets. Two engines lifted the rocket off the pad and then it crashed back down.

Pictures

• Empty engine casings and nozzles drying.
  
• Empty engine casings drilled, nozzle pieces and igniters.
  
• Close-up of igniters.
  
• Finished nozzles.
  
• Nozzles in engine casings.
  
• Nozzle retaining pins drying and crimp terminals added to igniters.
  
• Close-up of terminals on igniters.
  
• Finished engine casings with nozzles installed and retaining pins primed.
  
• One engine fueled and two igniters installed in core.
  
• All four engines fueled with igniters and end caps bolted together.
  
• Copper pipe hanging strap used as electrical buss for igniters.
  
• Close -up of ignition buss and rivets.
  
• Finished engine cluster. Not bad for $20.
  
• Smoke charges. 1 1/2" PVC with fuel poured in. Fuel is painted with epoxy on exposed ends to prevent moisture from being absorbed by fuel.
  
• End sections on smoke charge.
  
• Ejection charge. 003" brass shim stock inserted in PVC union as rupture disc.
  
• Smoke and ejection charge assembly.
  
• Smoke and ejection charge assembly mounted on forward bulkhead.
  
• Rocket body.
  
• Fin cut out of balsa wood strip.
  
• Threaded rods epoxied in balsa wood.
  
• Finished fins laminated with poster board.
  
• Close-up of threaded rods to be attached to rocket body.
  
• One fin attached to rocket body.
  
• Rocket body with all fins attached.
  
• Edge of fins treated with latex caulk.
  
• Finished rocket body primed.
  
• Forward bulkhead.
  
• Forward bulkhead installed in rocket body over engines.
  
• Ignition leads.
  
• Rocket with engines installed and smoke / ejection charge.
  
• Business end of rocket. Polypropylene plugs are inserted into rocket nozzles to seal fuel and prevent moisture from entering engines.
  
• Nosecone mold.
  
• Gauze and plaster in mold.
  
• 1/2 nosecone removed from mold.
  
• Two halves of nosecone held together with tape while epoxy is drying.
  
• Epoxy holding together the two halves of the nosecone.
  
• Nosecone primed.
  
• Nosecone painted.
  
• Parachute eye bolts installed on forward bulkhead.
  
• Finished rocket ready to fly.
  
• The launch tower before it was primed.
• Finished rocket in launch tower.
• Fin clearance in launch tower.
• Nose cone clearance in launch tower.
• Rocket and generator in van.
• It was hot in the desert.
• The rocket ready to fire.
• Ignition hook-up.
• Me next to the rocket.
• Launch switch.
• Generator next to the van.

Video

• 513 failed flight. Only two of the four engines lit due to the generator not producing enough power to ignite all the engine sets.
• Static test of the new Incendio engine, end cap blew out.
• Test firing of the new incendio engine.

CAD Drawings

• 513 rocket design.