Ryan Bocook

Sierra Space – Dream Chaser

About: Getting to work on building a space vehicle has always been a dream. I learned a ton about the similarities between building a space plane and an air plane and got introduced to the additional challenges of operating in low earth orbit. This build is still a work in progress and will head to environmental testing in Plumbrook Ohio before the launch pad for it’s first CRS2 mission to the ISS.

What I learned

  • The Dream Chaser Space Plane is a reusable lifting body vehicle designed to reenter the atmosphere and land on any runway that a 737 can use.
  • The design is inspired by NASA’s HL-20 vehicle, which in turn is from a pedigree of many lifting body designs
  • 1982 – The Russians were playing with lifting bodies and launched the BOR-4 – we were were spying on each other, obviously interested in anything that was deployed via rocket. Photos were taken by the the Australian Air Force and the Russians tried to hid behind a smoke screen as they recovered the vehicle from the sea.
  • 1999 NASA selects Boeing Integrated Defense Systems to design and develop a vehicle built in California’s Phantom Works. This vehicle is the X-37 which is now a classified vehicle designed to orbit for up to 270 days at a time. The Chinese have since launched and landed a similar reusable vehicle in 2020.
  • In 2006, a company called SpaceDev licensed the HL-20 design from NASA a decade after its cancellation. However, NASA didnt select the new Dream Chaser for their first Commercial Orbital Transportation Services Program.
  • In 2008, the founder of SpaceDev died and Sierra Nevada Corporation (SNC) purchased the company (SNC is a privately owned Defense Contractor known for retrofitting existing aircraft with military grade surveillance equipment and weapons)
  • in 2010, SNC won a round of Commercial Crew Development program under the Space Act Agreement and then later won a portion of the Commercial Resupply – 2 contract.
  • In 2021 SNC splits off Sierra Space as their own company so that they can focus on creating processes, systems and infrastructure needed to support the space business
  • There are 3 variants of The Dream Chaser vehicle family
  • DC100 is an un-crewed, autonomous vehicle heading to ISS, Orbital Reef, Free Flying Missions and National Security in Low Earth Orbit. This is the vehicle pictured above, which is Serial Number 1 (DC100.1 or UDC-1) under construction and has missions under NASA’s Commercial Resupply contracts.
  • DC200 is the crewed version in design which is currently 6 astronauts in LEO for the ISS, Orbital Reef, Free Flying, National Security missions
  • DC300 is un-crewed designed for Commercial, civil and national security in LEO, MEO, GTO
  • The cargo variant is designed for 9 launch cycles with a refresh at the Kennedy Space Center between each relaunch
  • The Un-crewed Dream Chaser (UDC) rides on top of ULA’s Vulcan Centaur rocket under a fairing and the wings must fold inboard to fit in the fairing. The wings deploy mechanism operates in zero G, so testing must simulate this environment. The crewed version is intended to not have folding wings for weight and simplification/de-risking.
  • The Shooting Star is the cargo module, also in construction in the same hanger as UDC-1. The cargo module is not reusable and will burn up on reentry. Therefore, many cargo modules must be made and simplified for cost out purposes.
  • The thermal protection system (TPS) on the vehicle is like the Space Shuttle and uses the same tile and non-tile approach. The tiles are bonded to SIP (strain isolation pads) made of Nomex felt with RTV silicone and then to the vehicle skin to create the OML of the vehicle. The gaps between the tiles were filled and the non tiled portions were covered with flexible FRSI blankets that were also bonded with RTV.
  • Tile placement, fixturing, application, cure times and fragility lead to delays on the shuttle
  • The nose landing gear is a skid which helps reduce weight, simplifies the design and packaging envelope when stowed.
  • The construction of the vehicle is not unlike XB-1 or other composite aircraft – similar processes, materials, tolerances (composites, adhesives, aluminum, titanium, fasteners, clickbonds and nut plates, fixtures, jigs, tools, FOD, quality, etc)
  • UDC-1 is still under construction in 2023, just north of Denver Colorado and UDC-2 structure is under way in the same hanger.

References

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