I've just made the mistake of consulting Wikipedia to check that my understanding of what a Rate 1 turn (which I'd always thought was 3 degrees per second) is correct.
"The aviation term ROT stands for rate one turn, also known as a standard rate turn. All aircraft must be able to perform a standard rate turn.
A standard rate turn for (light) airplanes is defined as a 3° per second turn, which completes a 360° turn in 2 minutes. This is known as a 2-minute turn, or rate one (= 180°/minute).
For heavy airplanes a standard rate turn is a 4-minute turn."
While Wikipedia is typically a great reference, it's wrong on that one. ROT stands for "rate of turn". There is not only rate 1 turns but rate 2 and 3 and I guess you could continue past that. Rate 2 is a 6 degree/sec turn and rate 3 would be a 9 degree/sec turn. Half rate turns are sometimes used as well; 1.5 degree/sec.
The speed limit for holding is typically 265 kts or Mach 0.83. The bank is limited to turn rate of 3 degrees/sec or a bank angle of 25 degrees, whichever is less. So no matter what speed you were flying, you'd never be pulling more than 1.1G.
But just for the sake of fun... I calculated the Concorde (any airplane for that matter) would be pulling 3.32G if it was in a steady, level 3 degree/sec turn at a speed of 1150 KTAS (~Mach 2). The angle of bank required is 72.45 degrees.
Yea, I seem to remember the angle of bank for a rate one turn is approx. your TAS / 10 + 7. So once you get a tas of 380 kts plus then you are over 45 degrees angle of bank to maintain a rate one turn, so not possible to achieve on most jet aircraft except in the hold on on approach.
That's why ICAO says to maintain a maximum of 25 degrees bank in the hold. It's unadvisable to go beyond 30 degrees bank while flying with reference to the instruments. It's very easy to get into a spiral dive or at least experience some difficulty maintaining speed and altitude beyond 30 degrees.
I remember reading in Brian Trubshaw's book on Concorde that although the holding speed was higher its handling characteristics were such that it's rate of turn allowed it to follow the same holding pattern as normal aircraft.
It's been said the Blackbird would start a 180 turn over Dallas, Texas and complete it over Wichita, Kansas, completely missing the state of Oklahoma. Checking an online turn calculator, that seems plausible too.
1,750 KTAS (~mach 3.0) 15 deg of bank 335 NM turn diameter 18 minutes to complete the 180 deg. turn (10 deg. per min.) 525 NM flown Straight line distance between Dallas and Wichita = 310 Nm