Long March 7A | Shiyan 12-01 & 02 (Auto Orbit)

Craft celebrating the launch of the 3rd Long March 7A flight carrying the Shiyan 12-01 & 02 sats to GTO

Mission - Shiyan 12-01 & 02

Like a large number of Chinese missions, limited information is available on the Shiyan 12-1 and Shiyan 12-2 spacecraft.This mission is a follow up to the Shiyan-9 and Shiyan-11 payloads.

Each spacecraft has a mass of 3 tonnes (6600 lb) and are labeled as technology demonstration satellites. They were developed by the China Association for Science and Technology (CAST).

Where is the satellite going? :

Geostationary Transfer Orbit (GTO)

Satellites operational Orbit:
Geostationary Orbit (GEO)
[8863 x 8863 km in Droo Orbit]

Rocket: Long March 7A

The Long March 7A (also known as the Chang Zheng 7A) is a 3 stage medium lift launch vehicle. It is able to put up to 13,500 kg into low-Earth orbit, and up to 7,000 kg into Geostationary Transfer Orbit.

First stage
The first stage of the Long March 7A consists of the center core and 0, 2, or 4 liquid fueled boosters. The core is based on the Long March 5’s core and is 3.35 meters in diameter. It has two keralox oxygen-rich staged combustion cycle YF-100 engines. Each engine produces roughly 1,200 kN of thrust and burns with a specific impulse of 300 seconds.

Each booster consists of a single YF-100 engine. In total the vehicle can produce up to 7,200 kN of thrust.

Second stage
The second stage is also 3.35 meters in diameter. It contains four keralox oxygen-rich staged combustion cycle YF-115 engines. Each engine produces 176.5 kN of thrust, has an ISP of 341.5 seconds, and a chamber pressure of 117 bar.

Third stage
The Long March 7A has a hydrolox third stage that is derived from the Long March 3B. The third stage uses two YF-75 engines. Each engine produces 78.45 kN of thrust and has an ISP of 438 seconds. This makes it one of the most efficient chemical rocket engines, behind the RS-25 with an ISP of 452 seconds, the RL-10 with an ISP of 465 seconds, and some other hydrolox engines.

————————————

Craft Notes:

1. Auto-Launch to Orbit by Preprogrammed Vizzy. (Throttle 100%)
2. Multiple Pad and Rocket Camera setups
3. Preprogrammed Vizzy for Launch and circulation phases (>550 x 550 km orbit)

*Fairing Deploy to be done after 115 km AGL (manuallly)
*FInal orbit insertion (GTO) and payload deploy to be done manually

Spacecraft Deploy Notes:

(wait for 60s after GTO transfer burn is completed)

1. Activate AG1 to activate separation groups
2. Activate AG2 to deploy Spacecraft 1
   (wait 30s)
3. Activate AG3 to deploy Spacecraft 2 shroud
   (wait 15s)
4. Activate AG4 to deploy Spacecraft 2

MISSION SUCCESS !!

————————————

Credits:

Predecessor Craft by 3DExplorer - China Long March 7A/E
Base Vizzy by: KAL

Modifications to Rocket, Space-crafts and Vizzy by OrbiteX