Saturday, April 25, 2015



This is a 'Turn Performance' flight model, designed to explore and match the turn rate performance of the actual 'Kfir' aircraft in X-Plane.
It Is an X-Plane 'Kfir' maneuverability demonstrator.

(Scroll down to read aircraft facts and flying tips for X-Plane flight simulator)

In general:
The current flight model of the VSKYLABS IAI 'Kfir' TC-2 gives a general perspective of it's real turn performance, based on it's Turn Performance Diagrams at 5,000, 15,000 and 25,000 feet. The 'Corner Velocity' was the main goal of achievement (actual performance diagrams of the 'Kfir' are attached below, for your use).

Corner Velocity:
In simple words, 'Corner Velocity', which also called 'corner speed' is the minimum speed at which maximum G can be obtained (at full engine power). Fly faster than it, and you can instantaneously pull to a maximum and even over-G turn (and lose energy in the process). Fly slower, and pulling all the way, will get your turn rate to drop rapidly, so the bad guy will gain angles as you'll lose energy.

Flying in the speed of 'Corner Velocity' is a good tactics in a dogfight. You are maneuvering at the best sustained turn rate of your aircraft, without losing energy, flying the air-combat geometry, and at the same time, you have the potential to 'go for the kill', or make defensive maneuvers by pulling harder into the maximum G or highest turn rate zone (which is usually not a sustained situation because of drag and thrust to weight ratio issues). 

For example, the corner velocity of the F-4E at 15,000 feet and maximum thrust is just above Mach 0.8, and it can hold up to 7G's sustained turn (depending on it's configuration) without losing energy. It's turn rate in this condition would be ~14 Degrees per Second. The corner velocity of the 'Kfir', at the same altitude is around Mach 0.7, but it's turn rate would be ~16 Degrees per Second. So, at 15,000 feet, the 'Kfir's' turn rate would be slightly higher, and it's corner speed would be slightly lower than the F-4E. I will discuss Dogfight tactics in another post :)

X-Plane flight performance note:
The VSKYLABS IAI 'Kfir' TC-2 flight model was tuned to match it's turn performance, but to do that in X-Plane, engine thrust had to be changed into higher values, and there are some changes (in the 'backstage') to the wing area and thickness, which are not visible and not affect it's delta-wing handling characteristics. These changes had slightly affected the accuracy of some non-drag consuming zones in it's flight envelope, but, all in all, and based on my experience, it's a good 'Kfir' maneuverability demonstrator. (Supersonic flight characteristics are not covered in this version, yet...).

Here are some performance charts for the 'Kfir C-7',
which is quite similar (the C-7 was a more powerful version):

The IAI 'Kfir' variants:
(I gathered this information with the help of Wikipedia, the free encyclopedia)

Kfir C.1:

Basic production variant.

F-21A Kfir: 
25 upgraded Kfir C.1 aircraft were leased to the USN and USMC for an aggressor role and were designated F-21A. These aircraft had been modified and included canards on the air intakes. These canards greatly improved the aircraft maneuverability and slow speed control, and were adopted on later variants.

Kfir C.2:
An improved C.1 that featured a lot of aerodynamic improvements. Changes included "dogtoothed" leading edges on the wings, small strakes under the nose and a larger sweep angle of the canards.

Kfir TC.2: 
A two-seat training variant developed from the C.2. It has a longer and lowered nose to improve the pilot's view.

Kfir C.7:
Vastly modified variant. Most if not all C.2 aircraft were modified to this variant. It included an improved J79-GEJ1E engine that offered more 1,000 lbs of thrust at full afterburner (and as a result increasing the Maximum Take-off Weight by 3,395 lbs), 2 more hardpoints under the air intakes, better avionics such as the Elta EL/M-2021B radar, HOTAS configured cockpit and inflight refueling capability.

Kfir TC.7:
A two-seat training variant developed from the C.7.

Kfir C.9:
Proposal for Argentina powered by Atar 9K50. Cancelled. Later developed as South Africa's Atlas Cheetah.

Kfir C.10:
A variant developed especially for export. The most important change is the adaptation of the Elta EL/M-2032 radar. Other changes include HMD capability and two 127×177mm MFD's. This variant is also known as Kfir CE ( Ecuadorean version ) and Kfir COA (Colombian version).

Kfir TC.10:
Upgraded version of the TC.7 for the Colombian Air Force.

Kfir C.12:
Upgraded version of the C.7 for the Colombian Air Force, a C-10 without the Elta EL/M-2032 radar.

Kfir Tzniut: Reconnaissance version of the C.2.

Flying tips (real life...and X-Plane):

Take off:

  • open full 'dry' power.
  • apply afterburenr after ~5 seconds.
  • rotate the nose up at ~150 knots.
  • at ~170 knots pull up a bit for clean take off.

After take off:

  • keep the nose up at ~15 to 20 Degrees for initial climb.
  • positive rate of climb, brakes, gear up.
  • let the aircraft gain altitude and speed in a shallow climb angle.
  • at 300 Knots you can retard the throttle back to full 'dry' power.
  • accelerate to ~400 knots for the climb and cruise (at higher altitude maintain Mach 0.85).
  • at or below 250 knots, retract the landing gears.
  • flying speed in the pattern - not less than 190 Knots.
  • start the final at 190 Knots, and bleed the airspeed to 170-180 Knots.
  • Final at ~5 degrees, use the HUD and the Velocity Vector.
  • engine to Idle when 'crossing the fence', and a gentle flare.
  • apply brake-chute, brakes.

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