Radius of turn rule of thumb
 

Not really sure this is the correct place, but what was the quick rule of thumb to quickly get a rough estimate of radius of turn?
Miles per minute minus 2? 240 knots would 4nm/min and minus 2 would be 2nm of radius?

What bank angle? What G?

Concorde used about 35nm radius to do a 180 at Mach 2.02 (1165 kts). Bank of 30° 1.15 g. Tha's just about exactly twice what your rule predicts. Rule = 19.5 nm/minute - 2 = 17.5nm, actual = 35 nm.

Anothe source says 20° bank, 1.06g, 52nm radius turn.

The Blue Angels (F-18 Hornets) had a dual maneuver I saw once. One plane in carrier-landing-config (flaps, gear, hook), the other clean at ~ 610 kts (700 mph). The fast plane would pass the slow one at the middle of the showline, and both would roll into 360-turns timed to return to the crowd at the same moment. "Slow and dirty" used about 0.4-mile radius (less than width of the Mississippi at that point), fast plane flew 3-mile+ radius way out over Arkansas. No idea what angle and G they used.

Google ; csgnetwork.com/aircraft turn performance........

I am just looking for a simple rule of thumb to use in the terminal area for a medium sized airliner (A320, 737, etc.) and that would make it easy to calculate when to turn into a DME arc and lead radial to turn off it.

See the below. I am not allowed to post the actual link at this point, delete the space before htm.
code7700.com/rot_turn_radius. htm

Old thread here

https://www.pprune.org/tech-log/1596...n-formula.html

One of the simplest rules-of-thumb that I've seen (assumes limiting bank angle of 25°) is to square the groundspeed (in nm/min) and then divide the result by 9, to give radius in nm.

Yes, that's it.

You had me worried for a moment - I teach maths as a sideline, so I ought to be able to explain things clearly. :O

I find the navigation formula of "About yea" does the trick most of the time."

1% of groundspeed, in still air, SRT.

Or, Mach number minus 2, still air SRT.

Using the original formula.... At 120kts = 2nm / m minus 2 is 0nm radius... Even less at lower speeds.

So best rule of thumb... Radius is 2nm.
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The Mach number -2 or nm/min-2 would work for speeds higher than 180 knots since we are limited to a bank angle of 25°.

I thought the other rule of thumb was TAS or GS divided by 200? 1% of GS is the diameter, isn't it?

Subject to assumptions about turn rate and bank angle, of course.

Just wondering if the OPs original formula should have had a divide by 2 sign, instead of a minus 2 sign...?
Still gives about the same answer...
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