ORIZONT
Photo
Gallery Orizont
About
Orizont
It is a project created in the days of the X Prize Competition. After
the end of the competition and the creation of the new STABILO vehicle,
ARCA operated some design modifications on this vehicle. The main purpose
of those modifications is to create a long range, high altitude vehicle
for future comercial aplications. The new variant received the "2B"
designation.
Flight
sequence
The vehicle will take-off from the ground with an expandable landing
gear.
It will climb at 13.000m during 190 sec. The final speed will be around
750 km/h.
At 13.000 m and 45 degrees angle the main hybrid rocket engine (Hydrogen
peroxide 85% and paraffine wax) will be ignited. Immediately after
the start the vehicle will begin to accelerate rapidly, the aerodynamic
surfaces putting the vehicle to a 60 degrees trajectory. This trajectory
will be kept for the entire time of the rocket engine run.
After the rocket engine shut-down the ship will continue to climb
inertial at an 60 degrees angle. The low atmospheric density from
those altitudes will not allow the pilot to control the attitude of
the ship from the aerodynamic surfaces and the ship will be controlled
with the reaction control system (RCS).
At the maximum altitude of 100 km, the ship will have the lowest speed
from the entire flight sequence. The pilot will continue to control
the ship with the RCS.
After reaching the 100 km altitude, the vehicle will start the descent.
For less then half the distance, the pilot will experience the effects
of imponderability. When the ship will encounter the first dense atmospheric
layers the use of the RCS is not necessary. For the landing procedures
the pilot will deploy the wing progresively. The landing will be made
on a runway using a lightweight landing gear.
The
Variable Geometry Wing
The most interesting element of the Orizont vehicle is the variable
geometry wing. The variable-geometry wing system offers the possibility
to use the vehicle both at low speeds and high speeds because of the
variable sweep angle. For low speeds the wing is used at low sweep angle
(near 0) and for the high speeds the sweep angle is increased to 70
degrees. The whole concept was determined by the necessity to put the
vehicle at altitudes around 13.000m using an external liquid fuel rocket
booster. The booster has 30.000 N max. thrust and uses hydrogen peroxide
85%+kerosen.
The low sweep angle offers the possibility to obtain a high lift, absolutely
necessary in high atmosphere. However, the drag generated by the wing
in this configuration is unacceptable at high speeds like those used
in rocket powered flight. The change of the sweep angle from 0 to 70
degrees leads to a dramatically decrease of the air drag and lift, in
the case of high speeds.
The change of the sweep angle is a complex technical problem which request
attention and precision. The weight penalty of such a system compared
with a fixed one is around 20%.
The biggest problems were those generated by
the changing position of the center of pressure and center of gravity
encountered during the wing sweep angle changes. The system offers the
answer to the high altitude climbing with a limited speed and the evolution
of the vehicle at high speeds.
The
Hybrid Rocket Engine and Fuel Tank
ORIZONT uses a hybrid rocket engine. The engine is built from composite
materials and uses Hydrogen peroxide 85% and paraffine wax. The engine
use the ablative cooling technology (inner layers vaporise in order
to keep outer layers at a resonable temperature). The internal structure
is made of silica phenolic composite materials and the extrenal structure
is made of carbon fiber/epoxy resin.
Finally, the fuel tank are also built from composite materials. This
technique started to be used by ARCA in 2001 and until now we had 100%
reliability during the tests and real flight.
The
Reaction Control System (RCS)
For flight control at high altitude where the atmosphere is very thin
and aerodynamic surfaces are inefficient, ORIZONT uses RCS. There are
12 small thrusters that use air under pressure. The thrusters do not
influence the trajectory, their only purpose is attitude control. RCS
is used when the pilot needs to reposition the vehicle, during reentry
and to avoid uncontrolled movement of the vehicle after the powered
flight phase and during the last 6 sec. of the powered flight.
Status
on June 2009: Airframe completed.
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