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RAIS
RAIS Redundant array of inexpensive systems
[architecture].
RAISD Research and Acquisition Information Systems
Division (Andrews AFB).
RAIU Receiver autonomous integrity unit.
RAJ Ring-around jammer (ECM).
Rajpo Range Joint Project Office.
RAKA Russian aerospace agency, also called
Rosaviakosmos, since 2003 the FKA.
rake 1 Angle between local vertical and swivel or castor
axis of swivel-mounted wheel, eg tailwheel.
2 Angle between quasi-straight edge of wingtip and
aircraft longitudinal axis, called positive * when leading
edge is shorter than trailing edge and negative * when
trailing edge is shorter.
3 Distance, measured parallel to aircraft longitudinal
axis, between front of propeller blade at tip and plane of
rotation through axial mid-point of hub (simple fixedpitch
propeller).
4 Acute angle between line joining centroids of
propeller blade from root to tip and plane of rotation
(often zero and possibly synonymous with 3).
5 Comb, linear or other array of pitot heads.
raked tip Sharp sweepback on extreme outer section of
wing, propeller/helicopter blade or other aerofoil.
raking shot Gunfire almost aligned with hostile aircraft
longitudinal axis.
RAL Rutherford Appleton Laboratory [SERC, now
part of CLRC; Chilton OX11 0QX] (UK).
Ralacs Radio-altimeter low-altitude control system
(RPV).
RAL-BCN See next.
RAL beacon Downwind of threshold, shows runway
alignment.
RALS, Rals Remote augmented lift system.
RALT Radar altitude.
RAM 1 Random-access memory.
2 Radar-absorbing [or absorbent, or attenuating]
material(s).
3 Research and applications module (Space Shuttle).
4 Rapid area maintenance (AFLC).
5 Raid-assessment mode (radar).
6 Reliable/available/maintainable.
7 Rolling-airframe missile.
8 Route-adherence monitoring.
ram 1 Increase in pressure in forward-facing tube, duct,
inlet etc as result of vehicle speed through atmosphere: if
fluid flow were brought to rest in duct pressure would be
q, dynamic pressure. Hence * inlet, * pressure, * -jet, * air,
* effect.
2 Main movable portion of hydropress; term not
encouraged for most hydraulic devices having linear force
output, for which actuator is preferred.
ram air Air rammed in at forward-facing inlet.
ram-air parafoil Flexible double-membrane wing
inflated for rigidity by ram air.
ram-air temperature That of ram air brought to rest with
respect to vehicle; stagnation temperature. Local temperature
on a surface subject to full kinetic heating, as at the
peak line along a leading edge, symbol T ram , normally
taken as T amb (1 + 0.2M 2 ).
ram-air turbine Small windmill extended into slipstream
to provide shaft power for essential services [eg., flight
ramp status
control or electric power] following total engine or electrical
failure.
Ramana Role of agile management in aerospace.
Raman effect Scattering, with change in polarization
and wavelength, of light passing through transparent
solid, liquid or gas.
ramark Fixed radio beacon continuously transmitting
(sometimes coded signal) to cause radial line on PPI
radars.
ramburner Turbofan which at Mach 2.5–4 closes off
core to become a ramjet.
RAMCC Regional Air-Movement Control Center
(US).
ram compression See ram (1).
RAMCS Rapid airborne mine-clearance system (USN).
Ramdi, RAMDI Radioactive miss-distance indicator.
ram drag See momentum drag.
Ramics Rapid airborne mine-clearance system (USN).
ram inlet Forward-facing inlet designed to achieve
maximum ram recovery, also called ram [or ram-air]
intake.
ramjet Air-breathing jet engine similar to turbojet but
without mechanical compressor or turbine; compression
is accomplished entirely by ram (1) and is thus sensitive to
vehicle forward speed and non-existent at rest (hence *
cannot start from rest). Inefficient at Mach numbers
below 3 but extremely important for unmanned vehicles,
esp. in conjunction with rocket (eg ramrocket). Also
called athodyd, Lorin duct; not to be confused with
pulsejet or resonant ducts.
RAM net Camouflage net made of RAM (2).
Ramos Remote automatic meteorological observing
station.
RAMP, Ramp 1 Robotic applications for modular
payloads (USA).
2 Radar modernization program.
3 Reconnaissance avionics maintainability program
(USAF).
4 Ramp control service.
ramp 1 Main aircraft parking area at airport, airfield,
airbase.
2 Sharp-edged wedge with sloping wall forming inner
wall of supersonic inlet duct to create oblique shock(s) and
improve pressure recovery, esp. at supersonic speeds;
usually has variable geometry.
3 Inclined track for launch of target, RPV, UAV or
missile under moderate acceleration.
ramp capacity Number of aircraft, of specified general
size class, for which ramp (1) is designed, including nosein
and off-terminal parking.
ramp check Visual external inspection of aircraft plus
replenishing hydraulic fluid, oil, water and other consumables,
plus checking tyres and brakes.
ramp extension Increase in size of ramp (1) to augment
capacity or allow for larger aircraft with wide turning
circles.
ram pressure Ram (1).
Ramps Resource allocation and multipath scheduling.
ramp services All services needed by civil aircraft on
transit stop or turnround, normally excluding mechanized
freight handling and supplies (eg pantry/bar
stocks) brought from terminal.
ramp status Accorded a new prototype after it has gone
‘out the door’ and is being readied for taxi tests.
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