PPRuNe Forums

Go Back   PPRuNe Forums > Flight Deck Forums > Tech Log
Forgotten your Username/Password?

Tech Log The very best in practical technical discussion on the web


Reply
 
Thread Tools
Old 23rd Sep 2011, 10:50   #1 (permalink)
 
Join Date: Jan 2008
Location: Reading, UK
Posts: 2,786
Rate One Turn

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."

http://en.wikipedia.org/wiki/ROT_(aviation)

Any comments ? Am I expecting too much of Wikipedia ?
DaveReidUK is offline   Reply
Old 23rd Sep 2011, 12:14   #2 (permalink)
 
Join Date: Aug 2002
Location: Up north
Posts: 1,115
From (FAR) AIM:

Quote:
STANDARD RATE TURN− A turn of three degrees per second.
CaptainProp is offline   Reply
Old 23rd Sep 2011, 21:56   #3 (permalink)
 
Join Date: Jun 2010
Location: Canada
Age: 27
Posts: 359
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.

imgur: the simple image sharer

Also of note, if you search just ROT in wikipedia it comes up correctly.

ROT - Wikipedia, the free encyclopedia
italia458 is offline   Reply
Old 25th Sep 2011, 09:07   #4 (permalink)
 
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,161
And not every airplane has to be able to do it!

Can you imagine a Concorde flying a holding at FL 370 with one rate turn?
How many gs would that be?
Microburst2002 is offline   Reply
Old 26th Sep 2011, 01:33   #5 (permalink)
 
Join Date: Jun 2010
Location: Canada
Age: 27
Posts: 359
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.
italia458 is offline   Reply
Old 26th Sep 2011, 02:31   #6 (permalink)
 
Join Date: Nov 1999
Location: The Land Downunder
Posts: 766
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.
Artificial Horizon is offline   Reply
Old 26th Sep 2011, 02:54   #7 (permalink)
 
Join Date: Jun 2010
Location: Canada
Age: 27
Posts: 359
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.
italia458 is offline   Reply
Old 26th Sep 2011, 10:50   #8 (permalink)
 
Join Date: Jun 2001
Location: UK
Posts: 2,613
Quote:
It's very easy to get into a spiral dive or at least experience some difficulty maintaining speed and altitude beyond 30 degrees.
Which is why, at an early stage of their training, military pilots spend a lot of time doing just that
Basil is offline   Reply
Old 26th Sep 2011, 19:14   #9 (permalink)
 
Join Date: Mar 2005
Location: Uh... Where was I?
Posts: 1,161
Any of you guys have flown "B figures" during training?

I'm not sure it they are a "local" thing where I trained or if it is universal
Microburst2002 is offline   Reply
Old 26th Sep 2011, 20:22   #10 (permalink)
 
Join Date: Dec 2006
Location: The No Trangression Zone
Posts: 1,820
I wonder if Concorde got a pass on limit holding speeds
Pugilistic Animus is offline   Reply
Old 26th Sep 2011, 22:24   #11 (permalink)
 
Join Date: Jan 2005
Location: France
Posts: 2,304
Quote:
Originally Posted by Pugilistic Animus View Post
I wonder if Concorde got a pass on limit holding speeds
PG, Concorde would 'hold' at the usual 250 to 300 kts, like everybody else.... not Mach 2 as an earlier poster suggested....
CJ
ChristiaanJ is offline   Reply
Old 27th Sep 2011, 03:21   #12 (permalink)
 
Join Date: Jun 2010
Location: Canada
Age: 27
Posts: 359
Quote:
PG, Concorde would 'hold' at the usual 250 to 300 kts, like everybody else.... not Mach 2 as an earlier poster suggested....
CJ
You must have skimmed my post extraordinarily fast...
italia458 is offline   Reply
Old 27th Sep 2011, 08:47   #13 (permalink)


Probationary PPRuNer
 
Join Date: Sep 2009
Location: South Wales
Age: 37
Posts: 3
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.

Is this turning into another Concord thread?
Ace Beer Charlie is offline   Reply
Old 27th Sep 2011, 09:12   #14 (permalink)
 
Join Date: Mar 2011
Location: Somewhere over the rainbow
Posts: 28
that rule really falls apart quickly at higher TAS
jpilotj is offline   Reply
Old 27th Sep 2011, 09:18   #15 (permalink)
 
Join Date: Jan 2006
Location: In a far better place
Posts: 2,326
Oh my... how about the SR-71??
captjns is offline   Reply
Old 27th Sep 2011, 10:15   #16 (permalink)
 
Join Date: Jun 2005
Location: USA
Posts: 680
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

So yeah!
westhawk is online now   Reply
Reply
 
 
 


Thread Tools


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT. The time now is 06:23.


vBulletin® v3.8.7, Copyright ©2000-2014, vBulletin Solutions, Inc.
SEO by vBSEO 3.6.1
1996-2012 The Professional Pilots Rumour Network