Tuesday, February 25, 2014
Friday, February 21, 2014
DCSS (Delta Cryogenic Second Stage)
The DCSS has been selected as the interim upper stage for
the first two flights of the Space Launch System (SLS), according to a
justification on NASA procurement website.
Based on the responses to that sources sought synopsis, NASA
determined that the DCSS is the only means available to support the immediate
in-space propulsion needs of the SLS within the SLS manifest schedule
constraints," says the agency, “the DCSS is the only known in-space stage
requiring relatively minor modifications to enable full compliance with the
requirements of the early SLS manifest."
The DCSS is powered by a single Pratt & Whitney
Rocketdyne RL-10B engine, fueled by liquid hydrogen, like this one:
The rocket has divided the political and space communities,
with supporters trumpeting its unprecedented capabilities and detractors
blaming the program for taking precious dollars from NASA. In any case, NASA is
now legally required to build SLS, earning it the derisive name 'Senate launch
system' in some corners.
RS-25
The RS-25 engines are the most powerful engines in the
world. Also they will be the first reusable engines in history. They were used
30 years ago on another mission, but now they know that they are the right ones
to carry with this mission. These engines are 200 feet long and have a diameter
of 275.6 feet of diameter. They will be the main engines powering the SLS. They
will also be the only ones to function on all of the missions while the
astronauts are in space.
The RS-25 will function with hydrogen and liquid oxygen
fuel. These engines are already in Florida for trials and they are installing
new technology like new hardware and a new battery.
Each engine will be equipped with a Main Engine Controller,
an integrated computer that controls all of the engine's functions and monitors
its performance.
These engines are very sophisticated because they have
50,000 parts. The engines produce a specific
impulse for 453 seconds in a vacuum, or 363 seconds at sea
level, consuming 1,340 L of propellant per second. They have a mass
of approximately 3.5 tones and are capable of throttling between 67% and 111%
of its rated power level in one percent increments. The RS-25 operates at
extreme temperatures, with the liquid hydrogen fuel being stored at 250 °C
while the temperature in the combustion
chamber reaches 3,315 °C
After 135 missions and more than 280 hours of trials, 100%
of missions succeeded. So before using this huge engine, that is referred to
with the nickname of “Clark Kent”, they will make further trials to show this
is not only the best engine in history but also the right one for the mission.
So these engines will allow the SLS to push 73 times faster than an
Indi-500 race car.
Here are some examples that NASA gives us on their official
page to know how powerful these engines are:
The fuel turbine that is on the RS-25 is so powerful that if
it were spinning an electrical generator instead of a pump, it could power 11
locomotives; 1,315 Toyota Prius cars; 1,231,519 iPads; lighting for 430 Major
League baseball stadiums; or 9,844 miles of residential street lights -- all
the street lights in Chicago, Los Angeles or New York City.
Pressure in the RS-25 is equivalent to the pressure of
submarine experiences three miles beneath the ocean.
The RS-25 engines will be starting their final trials
after they finish testing the J-2X, at the end of November 2014.
Tuesday, February 11, 2014
Orbital Maneuvering System- Israel Olvera
Orbital
Maneuvering System
The Orbital
Maneuvering System (OMS) is basically an hypergolic propellant powered engines
that are used by the shuttle during three phases: The ascent, the orbit and the
deorbit.
During the
initial launch, the engines sometimes may be used after main engine cutoff in
order to power up or boost the shuttle to the predetermined elliptical orbit. This
is called the OMS-1 burn. But it may not be required based on the payload and
mission.
Now, the
Orbital Maneuvering System-2 burn is used to circularize the elliptical orbit
that the shuttle first enters after launch. These engines may be used to change
the shuttle’s orbital characteristics during the mission.
The Orbital
Maneuvering System engines are used to deorbit the shuttle so it may reenter
Earth’s atmosphere.
The OMS provides enough power for orbit
insertion, orbit circularization, orbit transfer, rendezvous, deorbit, abort to
orbit, and abort once around. It offers more than 1000 pounds of propellant to
the aft reaction control system.
Aft Reaction Control System
The Aft Reaction Control System is a
spacecraft which uses thrusters to provide altitude control or even
translation. It uses diverted engine thrust to provide stable altitude control
of a short/vertical takeoff and landing aircraft.
_________________________________________________________________________________
Spacecraft reaction control systems are often used for altitude control while reentering the Earth’s surface, station keeping in orbit and control orientation.
The OMS is
stored in 2 independent pods located on each side of the orbiter’s aft
fuselage. The pods also house the aft RCS (Reaction Control System) and are
referred to as the OMS/RCS pods.
Each one of these
pods contains one OMS engine and the hardware that is needed to pressurize,
store and distribute the propellants to perform the velocity maneuvers. The
vehicle velocity required for orbital adjustments is approximately 2ft per
second for each nautical mile of altitude change.
During the first OMS thrusting phase, both
engines are used to raise the orbiter to a predetermined elliptical orbit.
Next, during the thrusting phase, vehicle attitude is maintained by supporting
the OMS engines. The Reaction Control System usually does not come into
operation with the OMS thrusting period. However, if during an OMS thrusting
period the OMS supporting (or gimbal) rate or gimbal period exceeds their own
limits, RCS attitude is required. In case that just one OMS engine is used
during the thrusting period, but RCS control is also required.
Attitude Control:
It is the exercise of control over the
orientation of an object respecting the inertial frame of reference or any
other entity such as certain fields, nearby objects, etc.
During the OMS-1
thrusting period, the liquid oxygen and liquid hydrogen that are trapped in the
main propulsion system ducts are dumped. The liquid oxygen is dumped out
through the space shuttle main engines’ combustion chambers and the liquid
hydrogen is dumped through the starboard side, which is the right side. This
velocity was pre-computed in conjunction with the OMS-1 thrusting period.
Once the
OMS-1 thrusting period is completed, the RCS is now used to null any residual
velocities (just in case it is required). The flight crew operates by using a
rotational hand controller or the translational hand controller to command the
applicable RCS thrusters to null the residual velocities.
The second OMS thrusting period using both OMS engines
occurs near the apogee of the orbit established by the OMS-1 thrusting period
and is used to circularize the predetermined orbit for that mission. The
targeting data for the OMS-2 thrusting period is selected before launch;
however, the target data in the onboard GPCs can be modified by the flight crew
via the CRT keyboard, if necessary, before the OMS thrusting period.
Upon completion of the OMS-2 thrusting period, the RCS
is used to null any residual velocities, if required, in the same manner as
during OMS-1. The RCS is then used to provide attitude hold and minor
translation maneuvers as required for on-orbit operations. The flight crew can
select primary or vernier RCS thrusters for attitude control on orbit.
Normally, the vernier RCS thrusters are selected for on-orbit attitude hold.
Bibliography:
“HSF-The Shuttle.” HSF-The
Shuttle. N.p., n.d. Web, 6 Feb. 2014
“Orbital Maneuvering
System.” Orbital Maneuvering System. N.p.,
n.d. Web, 6 Feb. 2014
Monday, February 10, 2014
Hydrogen and Oxygen Fuel
What it is:
Well, in my words and what i undersrand Oxygen fuel is like
technology that burns pure oxygen with gaseous fuel. For me is a mix of pure
air and gasoline.
The Hydrogen fuel is a zero-emission fuel which uses uses
electrochemical cells. It is combustion in internal engines. It is used to
power vehicles.
How they use it on the SLS:
They use the Oxygen Fuel and the Hydrogen Fuel to feel the
OV's (Orbiter Vehicle) tank, because like I have said it, they are like
GASOLINE.
Why do they use it on the SLS?
They use it because it is a liquid-fuel cryogenic rocket
engine that was used on NASA's Space Shuttle and is planned to be used on its
successor, the Space Launch System.
How it works in general:
Well in case of the Oxigen Fuel they use it to welding and
cutting. Welding: a welding torch is used to weld metals. Cutting: a torch is
used to heat metal to its kindling temperature.
In case of the Hydrogen fuel, it operates similar to a
battery.
Bibliography:
www.nasa.gov/.../sls
en.wikipedia.org/wiki/Oxy-fuel
en.wikipedia.org/wiki/Hydrogen-fuel
inventors.about.com/od/.../ss/Physics_Illustr_2.htm
ORBITAL MANEUVERING SYSTEM
ORBITAL MANEUVERING SYSTEM
The orbital maneuvering system gives the push for the
introduction for orbit, orbit circularization, orbit transfer, rendezvous,
deorbit, abort to orbit and abort once around, and can provide up to 1,000
kilos of fuel system aft reaction control. This is in two separate sheaths which
are on each side of the fuselage aft of the ship. In
pods are also the back RCS and are referred to as the OMS/RCS pods. Each
pod contains one OMS engine and the hardware needed to pressurize, store and
distribute the propellants to perform the velocity maneuvers. The two pods provide much abundance
for the OMS. Speed required for the vehicle which deals for
orbital adjustments is approximately 2 feet per second for each nautical mile
of altitude change.
PROPELLANT STORAGE AND DISTRIBUTION
The propellant storage and distribution system consists of
one fuel tank and one oxidizer tank in each pod. Also has propellant feed
lines, interconnect lines, isolation valves and crossfeed valves. the two fuel
tanks of the OMS. Enable the orbiter to reach a 1,000-foot- per-second
velocity change with a 65,000-pound payload in the payload bay.
The propeller is in domed cylindrical titanium
tanks within each pod. Each propellant tank is 96.38 inches long with a
diameter of 49.1 inches and a volume of 89.89 cubic feet unpressurized. The dry
weight of each tank is 250 pounds. The propellant tanks are pressurized by the
helium system. Preparing count four stub galleries and a collector manifold.
The stub galleries acquire wall-bound propellant at OMS and in rcs
speed operations not to introduce by mouth gases. The stub galleries have
screens that allow propellant flow and prevent introduce gases by
mouth. The collector manifold is connected to the stub galleries and also contains
a gas arrestor screen to further prevent introduce by mouth gases also contains
a gas arrestor screen to further prevent gas ingestion, which permits OMS
engine ignition without the need of a propellant-settling maneuver using RCS
thrusters. The operating pressure of each tank's nominal operating
pressure is 250 psi, with a maximum operating pressure limit of 313 psia.
A capacitance gauging system in each OMS propellant tank
measures the propellant in the tank. The system consists of a
forward and aft probe and a totalizer. The forward and aft fuel probes use fuel
(which is a conductor) as one plate of the capacitor and a glass tube that is
metallized on the inside as the other. The front and back oxidizer probes use
two concentric nickel tubes as the capacitor plates and oxidizer as the
dielectric. (Helium is also a dielectric, but has a different dielectric
constant than the oxidizer.) The back probes in each tank contain a resistive
temperature-sensing element to correct variations in fluid density. The fluid
in the area of the communication screens cannot be measured.
One tiny electric switch in each of the
ac-motor-operated valve actuators signals the respective valves' position (open
or closed) to the onboard flight crew displays and controls as well as
telemetry. An extensive improvement program was implemented to reduce the
probability of floating particulates in the tiny electric switch
portion of each ac-motor-operated valve actuator. Particulates could affect the
operation of the tiny electric switch in each valve and, thus, the
position indication of the valves to the onboard displays and controls and
telemetry.
CONCLUSION:
The job of the OMS is to propel and maneuver the shuttle
after it has arrived in space. It consists of two smaller engines located at
the rear of the orbiter on either side of the main engines.
WEB SITIES:
-Orbital
Maneuvering System
-Propellant
Storage and Distribution
-Wikipedia
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