(1/9) Most of us know the rocket engines used on #ISRO's rockets. But not as many know the smaller engines they built for use on their satellites to perform precise orbit raising/trajectory correction burns.
Let's get familiar with some of the lesser known engines of ISRO 🧵
(2/9) But first we gotta learn a few terms. A rocket engine runs in Blowdown or Regulated mode.
In Blowdown mode the propellant is pressurized with a fixed amount of helium. So as prop. is consumed, the pressure in the prop. tanks decreases.
(3/9) But in Regulated mode more Helium is continuously added to the tanks to keep a constant internal pressure.
Knowing this is important as it tells you if a spacecraft needs pressurant tanks in addition to prop. tanks.
Okay let's see the engines-
(4/9) Liquid Apogee Motor (LAM):
LAM comes in 2 flavours - one with 440N thrust (used on MOM, CY-1 etc) and the other with 800N thrust (used on Vikram lander). It runs on MON-3/MMH propellant, operates in regulated mode, uses radiative cooling and has a specific impulse of 315s.
(5/9) 50N thruster:
It's another runs on MON-3/MMH engine bipropellant which was used on Vikram lander for attitude control and also powers SSLV's 4th stage (VTM) Sadly this is the only info I could find about this engine.
(6/9) 22N thruster:
This engine was used on spacecrafts like MOM, CY-2's orbiter and GSAT series of satellites. Same hypergolic propellant, operates in blowdown mode, uses radiative cooling, and has a specific impulse of 285s. Like most ACS thrusters, it cannot be throttled.
(7/9) 10N thruster:
This engine was actually based on the 22N thruster and is used on GSAT satellites. Same propellant, blowdown mode and 285s specific impulse. But unlike the 22N thruster it uses both radiative and film cooling.
(8/9) 1N and 11N thrusters:
These thruster are monopropellant thrusters which were used on IRS and Cartosat satellites. Of these, I found that the 11N thrusters has a specific impulse of 220s and was also used on Astrosat.
(9/9) Finally the last engine I want to show is ISRO's electric thruster. GSAT-4 launched on GSLV Mk-2's maiden flight was the first Indian satellite to have electric thrusters but only went as far as the Bay of Bengal which is why GSAT-9 became the first such sat to reach orbit.
Thank you @Astro_Neel for providing two of the photos and @gareebscientist as some of the photos were taken from a video of yours 🙏
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