Evolution: Martian Star

This impulse evolution involves maneuvering the vessel in a series of inbound and outbound approaches around a planet (Mars). When completed, the maneuvers can be visulaised as forming a simple star pattern around the planet.

Skills

The evolution is intended to provide training and competency evaluation on the following impulse navigation skills:

  • Calculating and engaging bearings
  • Engaging held bearings
  • Relating maneuvers to grid position
  • Deceleration to a defined point

Proving Course

The evolution proving course is centred on a designated planet, usually Mars.

The starting point is on the X axis a distance from the first point of the ‘star’. The end point is within a target area 100 GU’s squared centred on the first point of the star.

Example Course

The example evolution is centred on Mars with co-ordinates X -1745 Y 15100.

The course points (CPs) for the evolution are:

CP Co-Ordinates Heading from CP
1

X -3445

Y 15100

000
2

X -2945

Y 15100

011
3

X -1945

Y 15300

079
4

X -1785

Y 16100

Radial
5

X -1705

Y 16100

281
6

X -1545

Y 15300

349
7

X -745

Y 15140

Radial
8

X -745

Y 15060

191
9

X -1545

Y 14900

259
10

X -1705

Y 14100

Radial
11

X -1785

Y 14100

101
12

X -1945

Y 14900

169
13

X -2945

Y 15100

End

Evolution Plan

You'll notice from this evolution plan that maneuvers are set up in advance, typically one or more course points from where they will have to be executed.

CP1

  1. Above: Evolution map (click for more detail)Get the vessel underway - a speed of .08C is recommended.
  2. The vessel starts the evolution at CP1, which is 500 GU's from the first point of the star (CP2).
  3. Set the Intercept Bearing Calculator (IBC) to target CP2.
  4. Use the radial slider to select the bearing required to give the correct heading from CP2.

CP2

  1. When CP2 is reached (the IBC will show zero range), engage the bearing.
  2. Set the IBC to target CP3.
  3. The required bearing from CP3 is 68° which is too large for a single maneuver. Break it down into a four-part held bearing of 17°.  Use the radial slider to select this bearing and select the HOLD mode.

CP3

  1. When the IBC shows zero range, engage the bearing and complete four maneuvering cycles.
  2. Set the IBC to target CP4. Make any minor heading adjustments indicated by the IBC.
  3. A radial traversal will be required from CP4 in order to maintain course. Calculate the required held bearing using the Held Bearing Calculator (HBC), entering your speed and a radius of 40GU.
  4. Select the calculated bearing (which will be a starboard bearing) on the radial slider and select the HOLD mode.

CP4

  1. When CP4 is reached (the IBC will indicate zero range), execute the held bearing until the position indicator shows the required heading from CP5 (281 degrees).

CP5

  1. When CP5 is reached (the IBC will indicate zero range), disengage the held bearing.
  2. Set the IBC to target CP6 and adjust heading as indicated.
  3. Use the radial slider to select the bearing required to give the correct heading to CP7 (68° broken down into a four-part held bearing of 17°).

CP6

  1. When CP6 is reached (the IBC will indicate zero range), engage the bearing and complete four maneuvering cycles.
  2. Set the IBC to target CP7 and adjust heading as indicated.
  3. Select the same bearing as used for the radial traversal from CP4 on the radial slider and select the HOLD mode.

CP7

  1. When CP7 is reached (the IBC will indicate zero range), execute the held bearing until the position indicator shows the required heading from CP8 (191 degrees).

CP8

  1. When CP8 is reached, disengage the held bearing.
  2. Set the IBC to target CP9. Make any minor heading adjustments indicated by the IBC.
  3. Use the radial slider to select the bearing required to give the correct heading to CP10 (68° broken down into a four-part held bearing of 17°).

CP9

  1. When CP9 is reached (the IBC will indicate zero range), engage the bearing and complete four maneuvering cycles.
  2. Set the IBC to target CP10 and adjust heading as indicated.
  3. Select the same bearing as used for the radial traversal from CP4 and CP7 on the radial slider and select the HOLD mode.

CP10

  1. When CP10 is reached (the IBC will indicate zero range), execute the held bearing until the position indicator shows the required heading from CP11 (101 degrees).

CP11

  1. When CP11 is reached, disengage the held bearing.
  2. Set the IBC to target CP12. Make any minor heading adjustments indicated by the IBC.
  3. Use the radial slider to select the bearing required to give the correct heading to CP13 (68° broken down into a four-part held bearing of 17°).

CP12

  1. When CP12 is reached (the IBC will indicate zero range), engage the bearing and complete four maneuvering cycles.
  2. Set the IBC to target CP13 and adjust heading as indicated.

CP13

  1. You will need to bring the vessel to all stop at CP13. Look up the deceleration distance at the vessel’s current speed (for .08C the stopping distance is about 295 GU’s at 80% thrust).
  2. When the IBC shows the stopping distance, engage reverse thrust.
  3. The vessel should come to all stop within +/- 50 GU’s of CP13.

Evaluation

For evaluation purposes, on completion of each CP no more than 6° correction to the next CP must be necessary.

The vessel must come to all stop within +/-50 GUs of the final CP.

Categories: