2. Your country to defend has one of the most mountainous topographies on this planet, where mountain chains are 2000m on average.
The Qaher is surely designed to make use of ground effect, its WIG like wingtips clearly point to it. Here is a technology where no experienced metallurgy is necessary, benefit by a physical effect affecting kinematics by developing a terrain avoidance system with digital maps and multiple redundant sensors. A mature terrain avoidance system for very low altitudes, state of the art. Ground effect was used on sea surface because land operation would be too dangerous but with today's technology this limitation can be eliminated.
A
ground effect vehicle (GEV) (aka WIG) is a
vehicle that is designed to attain sustained flight
over a level surface (usually over the sea), by making use of
ground effect. Although they may look and have related technical characteristics similar to
seaplanes,
ground effect vehicles are not aircraft, as they are unable to fly freely in the air. They are also dissimilar from
hovercraft or
hydrofoils, as they do not have any contact with the surface of the water.
Ground effect vehicles constitute a completely unique class of transportation.
A ground effect vehicle needs some forward velocity to produce lift dynamically and the principal benefit of operating a wing in ground effect is to reduce its lift-dependent drag. The basic design principle is that the closer the wing operates to an external surface such as the ground, said to be in ground effect, the more efficient it becomes.
An airfoil passing through air increases air pressure on the underside, while decreasing pressure across the top. The high and low pressures are maintained until they flow off the ends of the wings, where they form vortices which in turn are the major cause of lift-induced drag—normally a large portion of the drag affecting an aircraft. The higher the aspect ratio of the wing (that is, the longer and skinnier it is), the less induced drag created for each unit of lift and the greater the efficiency of the particular wing. This is the primary reason gliders have long and skinny wings.
Placing the same wing near a surface such as the water or the ground has the effect of greatly increasing the aspect ratio, but without having the complications associated with a long and slender wing, so that the short stubs on an Ekranoplan can produce just as much lift as the much larger wing on a transport aircraft, though it can only do this when close to the earth's surface. Once sufficient speed has built up, some GEVs may be capable of leaving ground effect and functioning as normal aircraft until they approach their destination. The distinguishing characteristic is that they are unable to land or take off without a significant amount of help from the ground effect cushion, and cannot climb until they have reached a much higher speed.
https://en.wikipedia.org/wiki/Ground_effect_vehicle
IMHO, Qaher 313 is not a Ground Effect Vehicle.
Principle of ground effect
When an aircraft flies at a ground level approximately at or below the length of the aircraft's wingspan or helicopter's rotor diameter,
there occurs, depending on airfoil and aircraft design, an often noticeable ground effect. This is caused primarily by the ground interrupting the
wingtip vortices and
downwash behind the wing. When a wing is flown very close to the ground, wingtip vortices are unable to form effectively due to the obstruction of the ground. The result is lower
induced drag, which increases the
speed and
lift of the aircraft. A wing generates lift by deflecting the oncoming airmass (relative wind) downward. The deflected or "turned" flow of air creates a resultant force on the wing in the opposite direction (Newton's 3rd law). The resultant force is identified as lift. Flying close to a surface increases air pressure on the lower wing surface, nicknamed the "ram" or "cushion" effect, and thereby improves the aircraft lift-to-drag ratio.
The lower/nearer the wing is with regards to the ground, the more pronounced the ground effect becomes. While in the ground effect, the wing requires a lower angle of attack to produce the same amount of lift. If the angle of attack and
velocity remain constant, an increase in the lift coefficient ensues, which accounts for the "floating" effect. Ground effect also alters
thrust versus velocity, where reduced induced drag requires less thrust in order to maintain the same velocity.
Low winged aircraft are more affected by ground effect than
high wing aircraft. Due to the change in up-wash, down-wash, and wingtip vortices there may be errors in the airspeed system while in ground effect due to changes in the local pressure at the
static source.
Another important issue regarding ground effect is that the makeup of the surface directly affects the intensity; this is to say that a concrete or other smooth hard surface will produce more effect than water or broken ground..
https://en.wikipedia.org/wiki/Ground_effect_(aerodynamics)
Did someone just suggest this is a low level penetrator? Like the Panavia Tornado, a multirole, twin-engined aircraft designed to excel at low-level penetration of enemy defences?
Variable wing geometry had been desired from the project's start. Advanced navigation and flight computers, including the then-innovative
fly-by-wire system, greatly reduced the workload of the pilot during low-level flight and eased control of the aircraft. The Tornado incorporates a combined navigation/attack
Doppler radar that simultaneously scans for targets and conducts fully automated
terrain-following for low-level flight operations; being readily able to conduct all-weather hands-off low-level flight was considered one of the core advantages of the Tornado
If F313 is designed to make use of ground effect, why not a low wing design, like F5, HESA Azarakash (model 2007) or HESA Saeqeh, or even a mid-body wing like HESA Azarakash (model 2008)?
To use ground effect, it needs to fly at 8-10 meters (F-5 and F16 span) altitude continuously..... in Iran's mountenous terrain.
This is Tornado flying low at high speed (probably about 80 m).
Here Typhoon (with flight heights mentioned)
http://www.dailymail.co.uk/news/art...-jets-fly-formation-each.html#v-3084998485001
F-111 low level oops