Solid Rocket Experiment
ARO 102L
Introduction of Astronautics
Try Lam
try.lam@jpl.nasa.gov
Mission Profile
Coast
Descent
Burn
Solid-Fueled Rocket Performance Project
Objective: This project is intended to provide a basic introduction to the mechanics of
rocket flight theory and experimentation with solid-fuel model rocket.
Three Phases
1.Static ground test
2.Assemble the rocket in class
3.Flying and flight measurement
Groups:
•You will split into groups of 5 to 6. Each group will analytically predict the time it takes
for each of the group’s rockets (5 or 6 rockets) to ascent, deploy their parachutes, and
return to the ground.
Equipment:
•NANO or Nimbs model rocket kit
•Estes A8-3 solid-propellant model rocket engine
•Assembly tools
•Measuring tools
•Stopwatch
•Launch pad
Solid-Fueled Rocket Performance Project
Procedures
Solid-Fueled Rocket Performance Project
Procedures
Rocket Assembly
• Carefully read and follow the instructions in the rocket kit!
Solid-Fueled Rocket Performance Project
Procedures
Measurements
•Measure the body tube diameter for drag estimation.
•Record the nose code shape for CD value.
•With the unburned rocket engine temporarily installed in your rocket, measure the
• Rocket mass
• Center of gravity location (form nose tip)
•Calculate the parachute’s drag coefficient by dropping the rocket with the parachute
open
• Find a two story building and drop your rocket off with the parachute
deployed.
• Measure the height dropped and the time it takes to fall.
• Measure the effective diameter of the parachute
• Compute the CD_para (below)
CD _ parachute =
W
æ1 2
ö
Aparachute ç rVparachute ÷
è2
ø
where
Vparachute =
Drop Height
Drop Time
Solid-Fueled Rocket Performance Project
Procedures
Pre-Flight Operational Checks
•Make sure that the nose cone can easily slip out of the body tube
•Make sure the parachute is not tangles up (might want to add some baby powder to
the parachute to ensure it doesn't stick or tangle).
Team Assignments
•Rocket launcher = the owner of the rocket
• Record the mass before and after launch
• Place rocket on launch pad (note which channel it is on)
• Go to the launch table
• Arm the launch system
• Loudly count down “3-2-1-fire”
• Push the igniter button
•Timers (x2)
• Stand at sides of the launch area
• Start timing when they here “fire” command
• Record the time at maximum altitude and time to ground
Solid-Fueled Rocket Performance Project
Procedures
Team Assignments (continues)
•Inclinometer (x2)
• Practice this before actual flight
• Stand 50 yards away form the launch stand
• Point the inclinometer at the rocket on the stand and pull the trigger to unlock
the pendulum pointer.
• Follow the rocket’s flight path pointing the inclinometer like a gun sight
• When the rocket reaches maximum altitude, the trigger will be released,
locking the inclinometer pointer at max inclination angle.
• Record the angle
Solid-Fueled Rocket Performance Project
Inclinometer & Altitude Calculation
Solid-Fueled Rocket Performance Project
Procedures
Pre-Flight Operational Checks
•Make sure that the nose cone can easily slip out of the body tube
•Make sure the parachute is not tangles up (might want to add some baby powder to
the parachute to ensure it doesn't stick or tangle).
Launch Operations
•See “Team Assignments”
•Record the time to max altitude
•Record the total time (launch to ground)
•Record data from the inclinometer (max inclination)
Solid-Fueled Rocket Performance Project
Post Launch Calculations
Engineering Calculations
•Calculate how high (in meters) the rocket is expected to fly based on your measured
mass and the published or measured characteristics of the A8-3 engine being used,
and how long it will take to get to the max altitude.
•You will have to estimate the drag coefficient of your rocket. Use the experimental
drag coefficient graph, consider your rocket’s shape, have the fins been streamlined,
shape of the nose cone, launch lug drag, etc.
•From the Estes A8-3 model rocket engine specs, the rocket has a burn time of tB = 0.73
sec, average T = 3.18 N, and a burnout mass of 10.2 g, total impulse = 2.5 Ns. Write
down yours
Specs
Reported Values
Your Values
Comments
Burn Time, tB
0.73 secs
Average Thrust, T
3.18 N
Burn out mass
10.2 g
Engine only
Total Impulse, Itotal
2.5 Ns
Itotal = Σ (T × Δt )
Graph from “Model
Rocket Altitude
Performance”, Centuri
Engineering Technical
Information Report TIR100, 1968
CD =
D
æ1 2ö
A ç rV ÷
è2
ø
CD º drag coefficient
D º drag force
A=
p
d2
4
º cross sectional area
r º density
V º velocity
Solid-Fueled Rocket Performance Project
Post Launch Calculations
Engineering Calculations
•Compute the total altitude (see “Useful Equations” slide)
•Compute the total descent time (see “Useful Equations” slide)
•Compute the total flight time (see “Useful Equations” slide)
•Compare calculated results to recorded results
Solid-Fueled Rocket Performance Project
Report
General
•Each is group is to turn in a TYPED report with everyone’s data
Cover Page
•Include course name, section number, experiment name, quarter, date
•Include group number and names of the group members
Summary Page
•Include objective
•Include key objective
•Include a brief conclusion
•Include something like the table below
Membe
r Name
Sanded
Fin?
Predicted
Time to
Max Alt.
(s)
Measured
Time to
Max. Alt.
(s)
% Error
for time
to Max.
Alt.
Predicted
Max. Alt.
(m)
Measured
Max. Alt.
(m)
[inclinomet
er)
% Error
for
Max.
Alt.
Predicted
Total
Flight
Time (s)
Measured
Total Flight
Time (s)
% Error
of Total
Flight
Time
Parachute
Open?
Bob
Yes
5
6
20%
50
55
…
…
…
5%
No
Sue
No
6
7
…
…
…
…
…
…
…
Yes
Solid-Fueled Rocket Performance Project
Report
Rocket Description Page(s)
•Include description of rocket, manufacturers, model, and engine type
•Include pictures, photos, diagrams, and describe the assembly process.
Launch System Description Page(s)
•Include description of launch system, platform, guide rods, and launch equipment
•Include pictures, photos, diagram
•Include a description of the launch process
• Described the launch mission profile
• Include details of what you recorded
Parachute Pre-Launch Test Description Page(s)
•Include description of parachute pre-launch test and the purpose of this test
•Include pictures, photos, or diagram of what you did
•Include equations and results form all member’s rockets (their Cd_para value, etc.)
Solid-Fueled Rocket Performance Project
Report
Static Engine Ground Pre-Launch Test Description Page(s)
• Include description of static engine ground test and the purpose of this test
• Include pictures, photos, or diagram of what you did
• Include equations and results form the ground test (e.g., the Isp values, thrust vs.
time plots)
Maximum Altitude Measurement Page(s)
• Include description of the inclinometer device and the measurement technique
• Include table and equations describing the conversion form recorded angle to
altitude
• Include photos, diagram, or pictures if you want
• Discuss if wind conditions affected your measurements
Other Measurement Page(s)
• Include description and discussion of any other measurements (if any)
Solid-Fueled Rocket Performance Project
Report
Calculation Page(s)
• Include equations, discussions, and results
• Include table of measurements, calculations, and errors
• Discuss anything that might be an error source or what might affect your results
Conclusion Page(s)
• Summarize the experiment, what you can do better, lessons learned, etc.
References
Appendix
• Any raw data, tables, notes, equations you want to include
Useful Equations
General Equations
A=
T - D -W = m
p
d2
4
D
æ1
ö
A ç rV 2 ÷
è2
ø
Ve = g0 I sp
CD =
DV = Ve ln ( m0 / m f )
Vpara =
tdescent
Thrusting (Burnout) Equations
h drop
t drop
h
= total
Vpara
ttotal = tb + tc + tdescent
htotal (max) = hb + hc
dv
dt
1
K = CD Ar
2
æT
ö
a0 = ç -1÷
èW ø
W
BC = º Ballistic Coefficient
K
æ
m
K ö
-1
tb =
tanh çVb
÷
T -W ø
K (T - W )
è
æ
a0 ö
Vb = a0 × BC tanh ç g × tb
÷
BC ø
è
æ
BC é
a0 öù
hb =
ln êcosh ç g × tb
÷ú
g êë
BC øúû
è
Useful Equations
Coasting Equations
Descent Equations
T =0
-D - W = m
dv
dt
tdsecent =
BC
-1 æ Vb ö
tc =
tan ç
÷
è BC ø
g
BC é Vb2 ù
hc =
ln ê1+
ú
2g ë BC û
( time to coast to V = 0 )
( altitude when V = 0 )
Coast + Thrust Altitude Equation
hmax = hb + hc
hb + hc
Vparachute
ttotal = tb + tc + tdsecent
Table of Results
Item
Symbol
Center of Gravity Location
Xcg
Empty Mass of Rocket
mrocket
Liftoff Mass of Rocket
m
Pre-launch Motor Mass
mmotor
Gravity
g
Liftoff Weight
W
Drag Coefficient
CD
Diameter of Rocket
d
Cross Section Area
A
Field Elevation
h
Air Density (at elevation)
ρ
Engine Type
Values
Estes A8-3
Average Thrust
T
Burn Time
tb
Propellant Mass
mprop
Specific Impulse
Isp
Units
Table of Results
Item
Symbol
Values
Thrusting and Coasting Calculations
Burnout Velocity
VB
Burnout Altitude
hB
Coast Altitude
hC
Coast Time
tC
Total Altitude
htotal
Parachute Descent Calculations
Parachute Diameter
dpara
Parachute Area
Apara
Drop Time (pre-flight)
tdrop
Drop Distance(pre-flight)
hdrop
Parachute Descent Velocity
Vpara
Parachute Drag Coefficient
CD_para
Descent Time
tdescent
Total Flight Time
ttotal
Units
Table of Results
Item
Symbol
Values
Units
Performance Calculations
Exhaust Gas Velocity
Ve
ΔV = Ve ln(minitial/mfinal)
ΔV
Item
Symbol
Values
Compare Calculation to Test Data
Total Altitude (calculated)
htotal_calc
Total Altitude (recorded)
htotal_data
% difference (error)
Erroralt
Total Flight Time (calc.)
ttotal_calc
Total Flight Time (record.)
ttotal_data
% difference (error)
Errortime
Units
Appendix
Model Rocket Assembly Instructions
Model Rocket Engine
Model Rocket
Model Rocket
Model Rocket
Model Rocket