SpaceX Falcon 9 Full Thrust - OrbComm OG2-2 - Launching December 21/22, 2015
Screenshot from SpaceX Webcast of the night launch of OrbComm OG2-2
Mission Rundown: SpaceX FT - OrbComm OG2-2
Written: February 1, 2021
Let’s try this boost back thing
With this mission, SpaceX’s Falcon 9 rocket will deliver 11 satellites to low-Earth orbit for OrbComm , a leading global provider of Machine-to-Machine communication and Internet of Things solutions. The OrbComm launch is targeted for an evening launch from Space Launch Complex 40 at Cape Canaveral Air Force Station, Florida.
If all goes as planned, the 11 satellites will be deployed approximately 20 minutes after liftoff, completing a 17-satellite, low Earth orbit constellation for OrbComm . This mission also marks SpaceX’s return-to-flight as well as its first attempt to land a first stage on land. The landing of the first stage is a secondary test objective.
This is the flight plan step by step, the boost back burn reverses the 1st stage's trajectory back toward landing zone 1 LZ-1. JRTI is only for ocean landings on GTO and some CRS missions.
The Payload
OrbComm Generation 2 (OrbComm -OG2) second-generation satellites are intended to supplement and eventually replace the current first generation constellation. Eighteen satellites were ordered by 2008—nominally intended to be launched in three groups of six during 2010–2014—and by 2015 have all been launched, on three flights. OrbComm has options for a further thirty OG2 spacecraft. The satellites were launched by SpaceX on the Falcon 9 launch system. Originally, they were to launch on the smaller Falcon 1e rocket.
This third launch, with the final 11 second-generation OG2 satellites, was successfully completed on December 21, 2015. It was initially scheduled for late-2014, but OrbComm delayed the launch until at least mid-2015 finally resetting the launch timeframe to mid-August through late-September 2015. The launch date was further delayed by the rocket failure on the SpaceX Falcon 9 Flight 19 launch in June 2015, which ultimately delayed the OG2 launch further out to late 2015.
The satellites were placed by the Falcon 9 launch vehicle "within a fraction of a degree in inclination and 5 kilometers (3.1 mi) in altitude of the intended orbit," and by 9 January 2016, were in the middle of on-orbit testing, while executing propulsion maneuvers that had spread the 11 satellites over a 6,400-kilometer (4,000 mi) orbital arc.
The OrbComm OG2 satellites are being manufactured by an industry team led by Sierra Nevada Corp and Argon ST, a Boeing subsidiary. A total of 18 OrbComm next-generation OG2 satellites were in production as of February 2013. OrbComm OG2 satellites will provide enhanced OrbComm messaging capabilities, increased capacity, and automatic identification systems (AIS) service. The agreement with SpaceX to launch 18 satellites on its Falcon 9 rockets was signed in December 2012 for a total cost of $42.6 million.
OrbComm ’s OG2 spacecraft were manufactured by Sierra Nevada Corporation and MicroSat Systems, around the SN-100A satellite bus. Argon ST, which is owned by Boeing, produced the satellites’ communication payloads. Each spacecraft has a mass of 172 kilograms (379 lb) and is designed to provide at least five years’ service.
Of the OG2 spacecraft already launched, FM101 was lost in a launch failure and FM111 malfunctioned after eleven months in orbit. The remaining spacecraft in orbit are currently believed to be healthy. By august 4, 2017 it’s rumored that only 12 OG2 Satellite Vehicles are operational of the OrbComm OG2 constellation, but no evidence can be found.
The Full Thrust Falcon 9
Falcon 9 Full Thrust has improved the previous model V1.1 by increasing the length of both the interstage and the second stage. The propellant/oxidizer has been densified by superchilling both RP-1 and especially the LOX, so it with the engine improvements has a 33% increase of performance during liftoff.
The Falcon 9 Full Thrust launch vehicle has a number of significant modifications from the previous Falcon 9 v1.1 vehicle. These included:
increased second stage tank length and propellant volume with 10%
The Merlin 1D+ engine had an increase of the sea-level thrust to about 730 kN (165,000 lbf) with a thrust-to-engine weight ratio of 180.
11 foot Merlin 1D+ vacuum engine nozzle with an expansion ratio of 165:1, and the engine can throttle down to 40% of its max. thrust, or 360 kN (81,000 lbf).
larger and stronger interstage 4,5 meter with revised stage separation mechanism the spring loaded center pusher in the vacuum engine bell
revised grid fin design a 4 by 5 feet aluminum 6 inch mesh to support the continuation of the Falcon 9 booster controlled-descent and landing tests, and ultimately, the operational Reusable Falcon 9 launch system
upgraded structure in the landing legs, also to support the reusable development program and objectives
upgraded first stage structure and welded octaweb engine support structure
denser liquid oxygen and RP-1 propellants through the use of subcooling below the typical temperature range of previous Falcon 9 launch conditions. A liquid Nitrogen tank with a heat exchanger supcools the LOX before loading in the tanks
Thus allowing more fuel and oxidizer to be stored in a given tank volume, as well as increasing the propellant mass flow through the turbopumps and increasing thrust with the superchilled propellant
liquid oxygen is subcooled to 66.5 K (−206.7 °C; 119.7 °R; −340.0 °F)
Liquid oxygen has a density of 1.141 g/cm3 (1.141 kg/L or 1141 kg/m3) when subcooled it has a density of 1.255 g/cm3 (1.255 kg/L or 1255 kg/m3)
RP-1 cooled to 266.5 K (−6.6 °C; 479.7 °R; 20.0 °F)
the capability of sub-cooling the RP-1 fuel to −7 °C is giving a 2.5–4% density increase from 0.81 g/cm3 (0.81 kg/L or 810 kg/m3) to 0.842 g/cm3 (0.842 kg/L or 842 kg/m3) given a 4% increase in density, a 20 to 30 kg pr. m3
the first stage booster can reach low Earth orbit as a single stage if not carrying the upper stage and a heavy satellite aka. it’s useful as an ballistic missile
The Falcon 9 Full Thrust with its satellite fairing stands 70 meters tall, the length is increased by 1,6 meters thanks to the changes in the second stage and interstage due to the improved Merlin 1D+ vacuum engine. The height is reduced by about 5 meters when launching a Dragon CRS mission to ISS.
The total fueled mass of a Falcon 9 Full Thrust is 549.000 kg. The first stage holds 410.900 kg propellant (287.400 kg LOX, 123.500 kg RP-1), and the second stage holds 107.500 kg propellant (75.200 kg LOX, 32.300 kg RP-1) leaving 30.600 kg to fill fuel tank pressurization COPV tanks with pressurized helium and for vehicle control a number of COPV tanks with cold nitrogen gas to use in the vehicle’s CRS thrusters.
This drawing by Ed Kyle has been used a couple of times before in chapters on V1.0 and V1.1 with rocket length in mind, now it's about calculating tank volume in cubic meters
Doing the Math: 287.400 kg LOX requires 229 m3 of tank volume, 123.500 kg of RP-1 requires 146,7 m3 of tank volume which totals 375,7 m3 tank space in the first stage. The diameter is 3,66 meters giving an area of pi x r2 = 10,52 m2, with the volume 375,7 m3 divided by area 10,52 m2, a given propellant tank min. height of 35,7 meters are found. And with a first stage height of 42,6 meter, that leaves 6,9 meter for the Octaweb’s 9 Merlin 1D+ in the engine bay, bulkheads, COPV and other nicknacks related to the first stage.
For the second stage we repeat the math. 75.200 kg LOX requires 59,9 m3 of tank volume, 32.300 kg of RP-1 requires 38,4 m3 of tank volume which totals 98,3 m3 tank space in the first stage. The diameter is 3,66 meter giving an area of pi x r2 = 10,52 m2, with the volume 98,3 m3 divided by area 10,52 m2 a given propellant tank minimum height 9,34 meter is found. I must ask myself if Wikipedia or Ed Kyle numbers can be thrusted later on.
With a second stage height of 12,6 meter, that leaves 3,26 meter for the 1 Merlin 1D+ vacuum engine, bulkheads, COPV and other nicknacks related to the second stage.
The interstage isn’t calculated regarding the overlap from stage one to stage two, other than the Merlin 1D+ vacuum engine is totally encapsulated, but 1,2 meter interstage is unaccounted for. Maybe that space is taken by either a bulkhead or the tripod center pusher for stage separation. There must be extra tank volume in case of overheating and thereby expanding LOX and RP-1.
The rocket hull mass and volume haven't been calculated either, since hull thickness, hull material density and specific hull construction aren't available for in depth calculation. The empty rocket mass or “dry mass” is available if you search for Falcon 9 on WikiPedia or search on Ed Kyle's homepage.
It’s sadly closed, and my old computer with some of his pages died.
Then there are rocket data wires, power wires, all sorts of fuel pipes, gas pipes, control valves and Reaction Control System thrusters, which all are unknown in lengths, thickness and mass. A 25 ton “dry mass” in the first stage is a fair estimate, but who but SpaceX engineers would know that for sure.
The total fueled mass of a Falcon 9 Full Thrust is 549.000 kg. That statement needs to be examined whether or not it is a supercooled propellant and oxidizer. Data must be confirmed from multiple sources first.
Following successful launch and deployment of the 11 OrbComm OG2 satellites, the Merlin Vacuum (1D+) second-stage engine successfully reignited in a test SES-2, there by demonstrating its capability to launch the next payload SES-9 into a geostationary transfer orbit.
The third engine burn SES-3 deorbited the second stage as planned for a destructive reentry, preventing it from becoming space debris. The propellant reserve that is estimated at less than 1% for this third deorbit burn can be used in an extra kick in supersynchronous transfer orbit burn to aid the payload in saving its propellant, when it’s shifting orbit to its geostationary 24 hour orbit. The 2nd stage then becomes a 4 ton piece of space debris.
A heavier payload decreases the second stage's capability to reach a higher transfer orbit, and decreases the first stage capability to return to the launch site or a barge downrange.
In August 2016, the returned first stage B1019 was eventually put on permanent display on a stand outside SpaceX headquarters in Hawthorne, California.
