Rate Of Turn

[flyer_by_the_wire]

Hey.....

I was a bit confused regarding the Rate Of Turn(Rate Two Turn specifically!!)

A rate 1 turn is 3dgrees per second..a rate two turn is 6 degrees per second..so while flying a rate two turn,a 360 degree tun should be completed in 1 minute..

But according to this article,

http://www.airdorrin.com/Resources/i...imedturns.html

a rate two turn is defined as 1 and a half degree per second

so this ways,the aircraft would take 4 minutes to complete a 360 degree turn.

so what should be the correct value??

thnx

[Bellerophon]

flyer_by_the_wire


...A rate 1 turn is 3dgrees (sic) per second

Correct.


... rate two turn is 6 degrees per sec...

Correct.


...a rate two turn is defined as 1 and a half degree per second...

Not correct.

As stated earlier in the article a turn rate of one and a half degrees per second is ... a Half Standard Rate Turn .... 1 1/2 degrees per second rate of turn ... and it will take you 4 minutes to turn 360-degrees....


Best Regards

Bellerophon

[flyer_by_the_wire]

@ Bellerophon

thank you so much for the reply..

But the article mentions that the HSRT is sometimes known as a RATE TWO TURN..

So have they quoted it wrong??

[aterpster]

Yegads! I'm lucky I didn't crash without knowing about Rate 1 and Rate 2 turns.

I was always taught (and then taught) standard rate turns. (3 degrees per second or two minute turns).

And, the U.S. military used to use 1/2 standard rate turns.

[plt_aeroeng]

Memory is a little fuzzy, but my recollection from the 60s was that in precision radar controlled approaches, 1/2 rate turns were expected once on final approach.

Another use for 1/2 rate turns were holding for a jet penetration at FL200: a standard rate turn would give an excessive angle of bank, particularly in a century series fighter.

BTW, a good GCA would give accuracy as good or better than Cat 1 ILS - a good thing, as sometimes in Europe an F86 pilot needed to get to the equivalent of Cat 2.5 by GCA, with no fuel for other options.

[bingofuel]

And to fly it, try an angle of bank equal to 10% of the airspeed +7
ie !20kts, bank angle would be 12+7 =19deg to achieve a rate one turn.

(That's if I have remembered correctly)

[Bellerophon]

plt_aeroeng

...a standard rate turn would give an excessive angle of bank, particularly in a century series fighter...

Yes, indeed.

For example, to have performed a rate 1 turn, in level flight in the cruise, in one passenger aircraft in the BA fleet not so long ago, would have required a bank angle of 73°, and pulling 3.23g.

Even a half-standard rate turn would have involved a bank angle of 58°, and pulling 1.89g.

Probably why we didn’t ever attempt them in the cruise!

In fact, most jet passenger aircraft will not attempt a rate 1 turn, in level flight in the cruise, as anything cruising around M0.85 and FL350 would need to use a bank angle of about 53° and pull around 1.66g.


bingofuel

...to fly it, try an angle of bank equal to 10% of the airspeed +7...

Well remembered; a formula still being used, which works well for any aircraft when flying at more modest speeds.


Best Regards

Bellerophon

[photofly]

Re 10% of airspeed+7:

It may be accurate enough, but it's still not very accurate, particularly at low speed. The correct expression should, I think, be arctan(v/364), where v is the speed in knots.

At 50 knots, the approximation gives 12 degrees where the right answer is 8 degrees. At 80 knots, 15, where the right answer is 12. By 130 knots the error is less than a degree. The two agree exactly at only one speed, which is about 160.5 knots.

[Microburst2002]

then the rule of thumb is really good

three degree error at the typical 80 kt TAS is very good

and Who wants to fly at 50 kt?

what i am not going to do is to get my calculator out of my flight bag and start dividing by 364

although I like to use it for other stuff quite often