Transcript Drag

Thrust
E80 Static Motor Test
Spring 2009
Forces on a Rocket
http://www.grc.nasa.gov/WWW/K-12/rocket/rktth1.html
The Question
• In the event of a crash landing of your
rocket, what will be the effect on the
instruments inside the rocket?
(Translation)
• What is the velocity of impact?
• What is the impulse response of the
rocket structure?
Solid rocket engine
Specific impulse
Static Motor Test
Static Motor Test
Static Motor Test
FT  mVe   Pe  P0  Ae  mVeq
m
m final  minitial
tburn
Veq 
m

tburn
FT ,average
m
Thrust Analysis
KINETICS
(Non equilibrium
processes)
Fuel Burn Rate
m
THERMODYNAMICS
(Equilibrium processes)
Exit conditions from nozzle
Ve
Pe
Kinetics of Solid Fuel Combustion
6NH4ClO4 ( s)  10 Al ( s)  4 Al2O3 ( s)  2 AlCl3 ( g )  3N2 ( g ) 12H2O( g )
 ENERGY !!!!!!
   fuel AsVburn
m
Vburn  kPt
n
Thermodynamics of Flow Processes
 AV  constant (mass balance)
h  12 V 2  constant (energy balance)
Isentropic Flow through Nozzles
dA
A
  1  Ma 2 
dV
V
For subsonic flow (Ma<1)
For supersonic flow (Ma>1)
For sonic flow (Ma=1)
dA
0
dV
dA
0
dV
dA
0
dV
Isentropic Flow of Perfect Gas Through
Converging-Diverging Nozzle
Ae
1  2    1
2 
1 

Mae 

*
A
Mae    1 
2

 1
2 1
Isentropic Flow of Perfect Gas Through
Converging-Diverging Nozzle
A
1

A* Ma
 2    1
2 
1 
Ma 

2

   1 
 1
2 1
Rocket thrust summary
E80 Static Motor Test Lab
1.
2.
3.
4.
Calibrate Load Cell
Measure Thrust Curve of Rocket Motor
Measure Average Mass Flow Rate
Compute combustion pressure assuming
isentropic nozzle flow. Model burn rate of
rocket fuel.
5. Estimate the impact velocity of your rocket.