SpaceX Falcon 9 Block 5 - Bangabandhu-1 - Launching May 11, 2018
Screenshot from Tim Dodd hosting SpaceX Falcon 9 with Bangabandhu-1 May 10
Mission Rundown: SpaceX Falcon 9 - Bangabandhu-1
Written: January 13, 2021
Now we have our workhorse
SpaceX is targeting the launch of Bangabandhu Satellite-1 on Friday, May 11 from Launch Complex 39A (LC-39A) at NASA’s Kennedy Space Center, Florida. The two-hour launch window opens at 4:14 p.m. EDT or 20:14 UTC.
Bangabandhu Satellite-1 will be deployed into a Geostationary Transfer Orbit (GTO) approximately 33 minutes after launch.
The Bangabandhu-1 Satellite mission will be the first to utilize Falcon 9 Block 5, the final substantial upgrade to SpaceX’s Falcon 9 launch vehicle. Falcon 9 Block 5 is designed to be capable of 10 or more flights with very limited refurbishment as SpaceX continues to strive for rapid reusability and extremely high reliability.
Following stage separation, SpaceX will attempt to land Falcon 9’s first stage on the “Of Course I Still Love You” droneship, which will be stationed in the Atlantic Ocean.
The Payload
Screenshot of Bangabandhu 1 in angle test under stress loads
Bangabandhu-1 was designed and manufactured by Thales Alenia Space. It is named after the father of the nation, Bangabandhu Sheikh Mujibur Rahman.
SpaceX will be launching the Bangabandhu 1 telecommunication satellite for the Bangladesh government telecommunication company . The built satellite will ride a Falcon 9 to Geostationary Orbit (GEO).
Bangabandhu 1 is equipped with 14 C-Band and 26 Ku-Band spot beam transponders with a 1600 megahertz capacity. The satellite will expand the Ku-band coverage over all of Bangladesh and its nearby waters including the Bay of Bengal, Nepal, Bhutan, Sri Lanka, the Philippines, eastern Indian states (West Bengal, Assam, Meghalaya, Mizoram, Tripura, Nagaland, Arunachal Pradesh) and Indonesia.
This is coupled with the C-band coverage for all aforementioned areas. It will be able to count holdings as well as to calculate the population density, depending on the natural increase and the natural decrease of birth rates and death rates in a particular country. It scans the number of people per 1,000 km2 with its advanced, installed technology such as cameras. The satellite will be located at an orbital location 119.1° East longitude and provide voice, data and video service to Bangladesh.
SpaceX Falcon 9 Block 5
SpaceX is launching their first "Block 5" rocket out at Launch Pad 39A at Kennedy Space Center, located at Cape Canaveral in Florida. It’s launching Bangladesh's first satellite called Bangabandhu-1, which is pretty small weighing only 3 700 kg. It's heading to a Geostationary Transfer Orbit, so the satellite will have to boost itself into its final orbit. This means the first stage will have to land on the "Of Course I Still Love You" drone ship 611 kilometers down range.
The Falcon 9 per usual stands 70 meters tall now in a black and white colour scheme with the standard 34 foot payload fairing. The black fire resistant legs have been redesigned to retract to avoid demounting the landing legs, but who knows if the legs don't warp during descent making it hard to relock the legs to the boosters locking pins. Spoiler.
This upgraded and "final" block change of the Falcon 9 features a black interstage vacuum engine cover, better and black thermal protection on the first stage for less refurbishment after recovery, black retractable landing legs, slightly increased thrust (8% to 845 kN) and new turbine blades inside the turbo pump in the Merlin 1D# engine. There's other tweaks, but this is the culmination of all landed and reflown Falcon 9 to date!
Another difference between earlier Falcon 9 blocks and Block 5 is a throttle function in the combustion chamber that delivers a constant thrust as the atmospheric pressure reduces, while the rocket ascends above the atmosphere.
The combustion chamber decreases its RP-1/LOX intake, which the earlier Full Thrust Falcon 9 didn’t do, so the combustion chamber pressure isn’t constant aka. “Full Thrust” with the side effect, that the thrust increased 10-15.000 pound-force pr. engine with the reduced air pressure outside the older Merlin 1D+ enginebell.
The only way to reduce thrust and therefore G-force on the payload was to turn the engines down during mach one, just before max Q and stage separation on the old Block 4 and the Full Thrust v1.2. Block 5 no longer needs to do anything other than to throttle down the RP-1/LOX intake of the turbo pumps in the engines to maintain the thrust in decreasing air pressure.
Another new feature is that the RP-1/LOX begins loading at T -35 min, which ensures that the propellant is as cold as can be before liftoff, so that a minimum of LOX gets too “hot” and evaporates away before launch. The LOX is pumped through a liquid nitrogen heat exchanger outside on the launch pad, before it’s pumped into the LOX tanks on the first and second stages of the Falcon 9 rocket.
The LOX tanks are kept chilled by helium bubbles stirring the LOX, giving it more “air” space to evaporate thus removing heat by venting boiled off oxygen through the engines plumbing , which are kept chilled just above working temperature. There are vents at the top of the LOX tanks on the first and second stages, which regularly release the excess pressure in the LOX tanks before liftoff.
But just how big are those LOX tanks?
By utilizing the ratio of LOX to RP-1 is 2,327 part LOX to 1,0 part RP-1 it can be assumed that if LOX density of 1.255 g/cm3 in super chilled condition and with RP-1 chilled density of 0.842 g/cm3, that 2,920 kg LOX + 0,842 kg RP-1 is consumed per second per engine.
3,762 kg propellant x 9 Merlin 1D# engines x 162 second burntime = 5 485 kg propellant.
But with the fact that the 9 Merlin 1D# engines have 410,9 ton of propellant in the first stage fuel tanks. We can now estimate the size of the parts of propellant in the LOX/RP-1 ratio by dividing the 410,9 ton with the 5,485 ton which gives 74,91 as the number of portions of propellant that a Merlin 1D# engine consumes. Is that the nozzle size?
74,91 x 3,762 kg propellant x 9 Merlin 1D# x 162 second = 410 900 kg propellant.
I have calculated the minimum tank volume in the first stage on both types of propellants by multiplying with the number of engines and the total burn time. 174,29 liter x 9 Merlin 1D# engines x 162 seconds burn time = 254 118 liter equivalent to 254,12 m3 of LOX tank space in the first stage. 74,91 liter x 9 Merlin 1D# engines x 162 seconds burn time = 109 219 liter equivalent to 109,22 m3 of RP-1 tank space in the first stage.
With 2 242,8 liters of propellant is consumed by the 9 Merlin 1D# engines every second of full thrust during liftoff. This is equivalent to 592,5 gallons of propellants to those metric impared. It can also be calculated as kilograms per liter using the LOX/RP-1 densities.
218,73 kg x 9 Merlin 1D# engines x 162 seconds burn time = 318 908,34 kilogram LOX.
63,07 kilo x 9 Merlin 1D# engines x 162 seconds burn time = 91 956,06 kilogram RP-1.
These calculations are minimum numbers on the first stage only, I have yet to do a more precise calculation on the second stage. There should be extra room for evaporation in the top tank dome and room for a number of COPV helium and nitrogen tanks.
An extra engine chilling makes sure that the LOX doesn't boil off immediately in a thermal shock on the metal engine parts, and because the Merlin 1D# engines prefer liquid oxygen pumped directly into the pressure chamber with cold -70 Celcius RP-1 before combustion and rocket thrust build up.
Falcon 9 Block 5 will be ready for NASA to certify it for human transport from American soil, but it must prove itself first through its reliability. That means the COPV Composite Overwrapped Pressure Vessel model 2.0 should fly at least 7 times without incidents before being certified by NASA. From booster B1047 they will be a standard fixture on the Falcon 9 Block 5 rockets.
This booster B1046 is equipped with the last old COPV model 1.0 and it was used later on in a spectacular in-flight abort test of the new Dragon 2 or Crew Dragon. Spoiler alert.
I have used the Scandinavian unit “km/t kilometer i timen” which should be kilometers pr. hour in english speaking countries. I’m sorry. It's been corrected by now.
No comments:
Post a Comment