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( T o p )
1
R e f e r e n c e s
T o g g l e t h e t a b l e o f c o n t e n t s
B S T A R
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A p p e a r a n c e
F r o m W i k i p e d i a , t h e f r e e e n c y c l o p e d i a
F
D
=
1
2
ρ
C
d
A
v
2
{\displaystyle F_{\text{D}}={\frac {1}{2}}\rho C_{\text{d}}Av^{2}}
where
ρ
{\displaystyle \rho }
is the air density ,
C
d
{\displaystyle C_{\text{d}}}
is the drag coefficient ,
A
{\displaystyle A}
is the frontal area, and
v
{\displaystyle v}
is the velocity.
The acceleration due to drag is then
a
D
=
F
D
m
=
ρ
C
d
A
v
2
2
m
{\displaystyle a_{\text{D}}={\frac {F_{\text{D}}}{m}}={\frac {\rho C_{\text{d}}Av^{2}}{2m}}}
In aerodynamic theory, the factor
B
=
C
d
A
m
{\displaystyle B={\frac {C_{\text{d}}A}{m}}}
is the inverse of the ballistic coefficient , and its unit is area per mass. Further incorporating a reference air density and the factor of two in the denominator, we get the starred ballistic coefficient:
B
∗
=
ρ
0
B
2
=
ρ
0
C
d
A
2
m
{\displaystyle B^{*}={\frac {\rho _{0}B}{2}}={\frac {\rho _{0}C_{\text{d}}A}{2m}}}
thus reducing the expression for the acceleration due to drag to
a
D
=
ρ
ρ
0
B
∗
v
2
{\displaystyle a_{\text{D}}={\frac {\rho }{\rho _{0}}}B^{*}v^{2}}
As it can be seen,
B
∗
{\displaystyle B^{*}}
has a unit of inverse length. For orbit propagation purposes, there is a field for BSTAR drag in two-line element set (TLE) files, where it is to be given in units of inverse Earth radii.[2] The corresponding reference air density is given as
0.15696615
kg
/
(
m
2
⋅
R
Earth
)
{\displaystyle 0.15696615{\text{ kg}}/(\mathrm {m} ^{2}\cdot R_{\text{Earth}})}
.[3] One must be very careful when using the value of
B
∗
{\displaystyle B^{*}}
released in the TLEs, as it is fitted to work on the SGP4 orbit propagation framework and, as a consequence, may even be negative as an effect of unmodelled forces on the orbital determination process.[4]
References [ edit ]
^ Hoots, Felix R.; Roehrich, Ronald L. (December 1980). SPACETRACK Report No. 3 Models for Propagation of NORAD Element Sets (PDF) (Report). Retrieved November 8, 2022 .
^ Vallado, David A., and Paul J. Cefola. "Two-line element sets-Practice and use." 63rd International Astronautical Congress, Naples, Italy. 2012.
R e t r i e v e d f r o m " https://en.wikipedia.org/w/index.php?title=BSTAR&oldid=1171641465 "
C a t e g o r i e s :
● S p a c e f l i g h t c o n c e p t s
● O r b i t s
● T h i s p a g e w a s l a s t e d i t e d o n 2 2 A u g u s t 2 0 2 3 , a t 1 1 : 1 5 ( U T C ) .
● T e x t i s a v a i l a b l e u n d e r t h e C r e a t i v e C o m m o n s A t t r i b u t i o n - S h a r e A l i k e L i c e n s e 4 . 0 ;
a d d i t i o n a l t e r m s m a y a p p l y . B y u s i n g t h i s s i t e , y o u a g r e e t o t h e T e r m s o f U s e a n d P r i v a c y P o l i c y . W i k i p e d i a ® i s a r e g i s t e r e d t r a d e m a r k o f t h e W i k i m e d i a F o u n d a t i o n , I n c . , a n o n - p r o f i t o r g a n i z a t i o n .
● P r i v a c y p o l i c y
● A b o u t W i k i p e d i a
● D i s c l a i m e r s
● C o n t a c t W i k i p e d i a
● C o d e o f C o n d u c t
● D e v e l o p e r s
● S t a t i s t i c s
● C o o k i e s t a t e m e n t
● M o b i l e v i e w