Powered Re-entry Vehicle
David Lammers
ASTE 527 Concept
13 December 2011
Why and What is Powered Re-entry?
Take advantage of on orbit refueling
ΔV burn to decrease re-entry velocity
Light weight
Lower heat of re-entry = no heavy heat
shield tiles
• Easier on passengers (lower decelerations)
• Easier on vehicle = reusability
• Unlimited cross range capability
•
•
•
•
– Land anywhere on the Earth you desire
Fuel Depot
Game changing technology to utilize future
on-orbit fuel depots
Powered Re-entry Vehicle
• Small vehicle
– Lightweight
– Decreases up and down propellant requirement
• Designed for a small crew only
– 3-6 astronauts
• Horizontal landing
– May incorporate air breathing/turboprop propulsion for
in-atmosphere range extension
PRV
• Must be delivered to space
– Ex. X-37
• X-37 architecture
• Build on sub-orbital platform
– Space Ship 2, Lynx, Super Mod, etc.
• Low weight materials
– Carbon composites
– Less (or no)TPS
Case Study: X-37
•
•
•
•
Phased design
Designed for a 3.1 km/s ΔV and 270 days in orbit
launch weight of ~ 5000 kg
Upgraded X-37C design announced 2011
– 165-180% scale of X-37B
– Carry up to 6 astronauts in modified cargo bay
Reported Cost ($ in millions)
• 1999: NASA 109, USAF 16, Boeing 67
• 2002: Boeing awarded additional 310 under SLI
• Total of $500 million
Case Study: Space Ship Two
•
•
•
Suborbital (~110km)
Max velocity ~ Mach 3 (SS1)
Increase drag through
“feathering”
– Highly stable
– Low skin temperature
•
Allows use of light
weight carbon
composites without
heat shield
Velocity Profile of Shuttle
Propellant Requirement
• Uses Ideal Rocket Equation which neglects all
forces other than thrust
9000
8000
"Final" Velocity (m/s)
7000
6000
Peak Heating Region
5000
4000
3000
5000 kg initial mass
(X-37B)
2000
5000kg burnout mass
1000
1200kg burnout mass
0
0
5000
10000
15000
Propellant Mass (kg)
20000
25000
30000
Size Comparisons of X-37 and Shuttle
• Shuttle loaded mass 381,600 kg (estimate)
– 81,600 kg dry mass
• X-37B loaded mass 4,990 kg
– 2,600 kg dry mass (estimate)
Reusability is Key
• Low mechanical stress and low heat
buildup on vehicle should lead to a highly
reusable system
• Need to keep turnaround costs down
– Est. $450 million per shuttle launch
– Ideally the craft could be reused quickly with
almost zero cycle cost
Multiple PRV’s
• Economies of scale
• More customers
– Nations
– Private industry
– Individuals
Credit: Buzz Aldrin
Future Work
• Feasibility
– Would a system like this really work
• Simulation comparing reentry velocity,
drag, delta V, aerothermal simulation, etc.
• Figure out maximum velocity that the
“feathering” technique could be employed
– Initial thought it needs to be done at the apex
of a trajectory, thus a very low (almost zero)
velocity
References
http://www.af.mil/information/factsheets/factsheet.asp?fsID=16639
http://www.protechcomposites.com/pages/High-Temp-Panels.html
http://blogs.voanews.com/science-world/files/2011/09/iss.jpg
http://scienceblogs.com/startswithabang/upload/2009/05/could_an_ast
eroid_have_wiped_o/impact3.jpg
http://spacesolarpower.info/wpcontent/uploads/2011/10/fotovoltaico_spaziale.jpg
http://up-ship.com/blog/?p=639
http://buzzaldrin.com/space-vision/rocket_science/multi-crew-modules/
http://www.nasa.gov/centers/kennedy/about/information/shuttle_faq.h
tml
blogs.airspacemag.com/.../10/x37-still-aloft/
http://www.boeing.com/defense-space/space/hsfe_shuttle/facts.html
Powered Re-entry Vehicle
BACKUP SLIDES
Reentry, as it is Now
Shuttle
– Mach 25 at 120 km
– TPS = 8574 kg (30,000 tiles)
• Includes all types of tiles FRSI, LRSI (FIB), HRSI,
and RCC
FRSI < 371 C
FIB < 649 C
HRSI < 1260 C
RCC > 1260 C