Flight Readiness Review

Student Launch Initiative

SCS Rocket Team

Statesville Christian School

April 2, 2008

The Rocket

The Rocket Details

• The Static Margin for the rocket, if we can build it to the minimum mass of about 9 lbs will be about 5, according to simulation performed in RockSim.

• The rocket will most likely have a mass of 10 to 11 lbs. This mass will be mainly in the front of the rocket resulting in a Static Margin greater than 5.

• Our rocket design is stable.

• Using the Cesaroni K1440 motor, our average thrust to weight is 32:1 for a 10 lb rocket and the peak thrust to weight is about 48:1 for the same weight rocket.– This is much higher than the “rule of thumb” value

of 5:1 for stable flight after the rocket leaves the launch rail.

• Using an 8 ft launch rail, the rocket leaves the rail with a velocity of 102 mph, according to RockSim. – Using a “rule of thumb” velocity of 30 mph off the

launch rail for stable flight, the rocket will be stable off the rail.

Rocket Recovery• Drogueless at apogee with 15 ft long Kevlar shock

cord connecting the fin can to the upper rocket section– Motor ejection is at 17 seconds from engine cutoff with

Loki ARTS II altimeter firing a charge at apogee for backup.

• A 60 inch Loc Parachute will be ejected at 1000 ft by the Loki ARTS II altimeter with 15 ft of Kevlar shock cord.

• Descent rate with this parachute is 20 ft/sec assuming the rocket mass is 10 lbs on the launch pad

Test Plans and Procedures

• Rocket Testing Plan:– Altimeter Testing

• Change in Pressure Test (Evacuated Jar and diodes/lamp)

– Apogee Detection– Dual Deployment

• Will the altimeter light the E-Match? (Via Laptop)• Will the altimeter light two E-Matches? (Via

Laptop)• Determine black powder amount necessary for

ejection charge to shear 3 nylon pins

• Payload Testing– Reverse Thrust Motor ignition detection

method– Remote transmission of pressure

information to base station from electronics payload

• Distance• Integrity

– Accurate data from pressure sensors– G-Force robustness of payload

The Scale Model Flight

• We have successfully flown the scale model with and without the reverse thrust motor ignited!

• The rocket was stable for both flights.• We used an Estes E9 motor as the reverse

thrust motor. • The only real difference noted was that while

flying the rocket with the RTM twice, we noticed there was no wind cocking.– The wind was averaging about 10 mph for both

flights with the reverse thrust motor lit.

Dual Deployment Avionics Test

• The Dual Deployment Avionics uses a Loki ARTS II altimeter.

• The altimeter will be set to fire an ejection charge at apogee and at 1000ft above ground level.

• We plan to test the altimeter by placing it in an airtight jar and progressively pumping the air out of the jar. We will then stop and slowly let air back into the jar.

• We may need to slightly “jar” the altimeter to simulate liftoff of the rocket.

• Small light bulbs/ammeters will be attached to the apogee and main parachute connectors to determine if the altimeter attempted to fire the ejection charges.

• We will also examine the altimeter data to confirm pressure changes.

Ejection Charge Amount Test

• Using an online calculator, the amount of 4F black powder we need for our ejection charges is 0.67 of a gram.– This yields 15 lbs/in2 pressure in a 12 inch

long 3 inch diameter tube.– This will permit 3 2-56 nylon shear pins or

2 4-40 nylon shear pins. The current plan utilizes 3 2-56 nylon shear pins.

• We plan to test our rocket using 1.0 gram of 4F black powder with the rocket flight configured (except for the motor).– This gives approximately 160 lbs of force on the

bulkhead. Since each 2-56 pin shears reliably at 35 lbs of force, this should allow three shear pins to be used with our rocket.

• We will use the laptop to ignite the charges with the rocket configured for flight. A drogue and main separation test will determine if this amount of 4F black powder will break the shear pins and safely separate the rocket.– This is a feature of the Loki ARTS II altimeter

software.

Payload Integration Feasibility• The electronics payload will be housed in the

same bay as the altimeter. – Both will be on the same “sled” with batteries on the

backside– Switches for the altimeter and electronics payload will

be located on the sled between the two devices• Switches will be accessed by a porthole in the payload section

that will be plugged during flight.

Outer Tube Coupler for Bulkhead Stop

Sled for AltimetersEyebolt

Through Rod Assembly

ElectronicsPayload AltimeterSwitches

• Wires will run inside a tube from the bottom of the rocket to the electronics payload section. This is for ignition of the RTM.

• A wire will run from the payload section to the nosecone attached to a thin sheet of Aluminum foil for detecting when the RTM has fired.