$LastChangedDate: 27-Juil-2011 $

# CL_man_sma

Delta V required to change the semi-major axis

## Calling Sequence

       [dv,anv] = CL_man_sma(ai,ei,af [,posman,mu])

## Description

- Computes the delta-v required to change the semi major axis.

  The maneuver consists in modifying the periapsis or apoapsis radius only, and only one maneuver is performed: at periapsis or at apoapsis.

  The output argument dv is the delta-V required expressed in spherical coordinates in the QSW frame: [lambda; phi; |dv|], where lambda is the in-plane angle (+%pi: towards planet and +%pi/2: ~along velocity), phi is the out-of-plane angle, positive towards the angular momentum vector (the angular momentum vector is perpendicular to the orbit plane and oriented according to right hand convention), dv is the norm of the velocity increment.

  anv is the true anomaly at the position of maneuver.

## Parameters

ai :

  Initial semi major axis [m] (1xN)

ei:

  Initial eccentricity (1xN)

af :

  Final semi major axis [m] (1xN)

posman:

  (optional) flag specifying the position of maneuver (0->periapsis, 1->apoapsis; default is 0) (1xN)

mu :

  (optional) Gravitational constant. [m^3/s^2] (default value is %CL_mu)

dv :

  Delta_v in spherical coordinates in the QSW frame [lambda;phi;|dv|] [rad,rad,m/s] (3xN)

anv:

  True anomaly at the position of maneuver [rad] (1xN)

## Authors

- CNES - DCT/SB

## See also

- CL_man_biElliptic

- CL_man_hohmann

- CL_man_hohmannG

## Examples

    ai = 7200.e3;
    af = 7000.e3;
    ei = 0.1;
    [dv,anv] = CL_man_sma(ai,ei,af)
    // Check results :
    kep = [ai ; ei ; %pi/2 ; 0 ; 0 ; anv];
    kep1 = CL_man_applyDv(kep,dv)