Powered Re-entry Vehicle

David Lammers

ASTE 527 Concept13 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

0 5000 10000 15000 20000 25000 300000

1000

2000

3000

4000

5000

6000

7000

8000

9000

Propellant Mass (kg)

"Fin

al"

Velo

city

(m/s

) Peak Heating Region

5000 kg initial mass(X-37B)

1200kg burnout mass5000kg burnout mass

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

Credit: Buzz Aldrin

• Economies of scale• More customers

– Nations– Private industry– Individuals

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=16639http://www.protechcomposites.com/pages/High-Temp-Panels.htmlhttp://blogs.voanews.com/science-world/files/2011/09/iss.jpghttp://scienceblogs.com/startswithabang/upload/2009/05/could_an_asteroid_have_wiped_o/impact3.jpghttp://spacesolarpower.info/wp-content/uploads/2011/10/fotovoltaico_spaziale.jpghttp://up-ship.com/blog/?p=639http://buzzaldrin.com/space-vision/rocket_science/multi-crew-modules/http://

www.nasa.gov/centers/kennedy/about/information/shuttle_faq.html

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 CFIB < 649 CHRSI < 1260 CRCC > 1260 C