Mnimum turn radius

Hello,

What is corner velocity and g load, to achieve min turn radius for Mig21...?

Min turn radius: Around Mach 0.75-0.80 ( Weight 7.500 Kg ) Sea Level - 1000 meters.

Minimum sustained turns according manual:

1.Second reheat, weight 7500 kg, 0,5 Ma:

- 1000 m (altitude) - 760 m (radius);

- 2000 m - 880 m;

- 3000 m - 960 m,

2.First reheat, weight 7500 kg, 0,5 Ma:

- 1000 m - 870 m;

- 3000 m - 1030 m;

- 5000 m - 1320 m.

Minimum sustained turns according manual:

1.Second reheat, weight 7500 kg, 0,5 Ma:

- 1000 m (altitude) - 760 m (radius);

- 2000 m - 880 m;

- 3000 m - 960 m,

2.First reheat, weight 7500 kg, 0,5 Ma:

- 1000 m - 870 m;

- 3000 m - 1030 m;

- 5000 m - 1320 m.

Sorry:

0.75-0.80 is for a min turn radius in time.

Min distance is at 0.5 Mach.

Manual

"minimum turn radius in time" makes no sense. Either you are minimizing time or minimizing radius. They happen at different speeds. Minimum radius will occur at slower speed than minimum time.

Corner speed is minimum speed that reaches load limit (8g, 7g, ...4g depends on configuration). Traditionally and in this case as well it is also the maximum turn rate possible.

I mean this:

Min time for a steady turn. I hope now makes sense for you. At 1000 meters and Mach 0.75 the Mig-21 is able to do a sustained turn ( space ) in the shortest amount of ( time )

Thank you very much.

Is there any Angle of Attack given for minimum turn radius?

I only understand the units given for the charts but not the explanations... :helpsmilie:

Radius of turn is better with more load and worse with faster speed. But of course speed helps develop load. Low speeds load is small so radius is large. For high speeds even though high load can be applied the speed increases the size of the circle. It is a moderate speed which is the minimum radius turn.

Rate of turn however gets better and better the faster you go provided the airplane's load limit is not reached. Corner speeds is the corner on the graph where the increasing turn rate meets the loading limit.

Be aware that optimizing turn radius is less often helpful than optimizing turn rate. Having a turn diameter of a kilometer isn't of much help if it takes takes a long time to make that turn. A faster-but-wider turning opponent will usually out perform a slower-tighter turning airplane.

Compare corner speed to minimum radius on F-16 at 0.28M versus maximum rate at 0.54M. It's practically 2:1 ratio. Tight turning is doing 13 degrees per second and fast turn is doing 28 degrees per second.

In MiG-21bis it depends if you are using the ARU tail in auto or maximum travel. With ARU in auto you can only hit 8g at ~1100 kIAS. With ARU low speed able at about 750 kIAS and also happens to be at 28-33 UUA-1. I see 15 dps auto and 20 degrees per second rate at 8g/750kIAS. Radius is ~1km auto and low speed 600-700m.

But minimum radius is happening at ~420 km/h about 500m. But turn rate is 14 degrees per second.

Lastly there is a question if these turns can be sustained by the engine's power or will slow down. Sustained best rate is maybe 12 dps at 5-5.5g (7500kg, second AB). Radius is pretty constant instant and sustained at lower speeds.

Thank you guys for thorough explanation... :D