the turn fight and why it kills

[crutch]

Warning!  Some boring physics stuff.

Turn-fighting is probably the most used form of ACM and the least understood.  Any two aircraft, propeller, jet or rocket driven, will have exactly the same turn radius and rate IF they have the same airspeed, bank angle and G-loading.

They can and will have differing capabilities for maintaining those turn factors.

Examine the three tables; Turn radius, Turn rate and Turn time in the Appendix.

The Turn radius table was created using this formula: R =  V^2/A.
R = radius of the turn in feet
V = speed of the aircraft in feet per second, squared
A = acceleration in feet per second per second, 1 G = 32.2 feet/sec/sec.

The Turn rate table was created using this formula: w =  360 / (2 * PI * R) / V.
w = Degrees per second
R = radius of the turn in feet
V = speed of the aircraft in feet per second
PI = Mathematical constant = 3.14159.

The Turn time table was created using this formula: T =  360 / w.
T = time for one complete 360 degree turn
w = Degrees per second.

After examining the data in the tables, you can see changing the G-load has more effect than a small speed change.  Think of it as changing to an inside lane at on a racetrack.  You are now turning a smaller circle but you are also paying a penalty for the smaller circle.

You can see an aircraft’s best turning numbers are unique for a sustained turn.  Two aircraft can fly matching turns but one will be able to hold those numbers for a longer period than the other.

This is where the confusion about aircraft ‘A’ being out turned by aircraft ‘B’ comes from.  When ‘A’ has a better, by the book, turning rate.  The rate was for a very specific set of conditions.

The rate you have to deal with now is the one handed to you by the bandit you are facing in the turn now.

How does this translate to an actual fight?

[crutch]

How does this translate to an actual fight?

Example:
Two pilots are fighting a duel, each are flying the same aircraft, Spitfire Mk 9s.  Both pilots have the same fuel and ammunition loads.  The determining factor here is pilot skill.

Each pilot enters a turn with exactly the same airspeed (250 IAS) and G-load (3 Gs) and they are in full knife edged (90 degree) banks.

Examining the table for their turn factors gives a turn radius of 1,392 feet.  They are both turning 15.1 degrees per second, completing a full circle in 24 seconds.

This is just like two kids chasing each other around a table and running at the same speed.

Pilot ‘A’ thinks he can catch up to pilot ‘B’ by increasing his airspeed and he pushes his throttle to the stop, accelerating to 275 IAS. He is starting to black out at 3 Gs and he does not want to pull any more.

Will he catch pilot ‘B’?  No

The why is complicated.  Unlike the kids, pilot ‘A’ does not have friction with the floor holding him in his turn.  Pilot ‘A’ increased his speed by 25 MPH but held his G-load steady.  This increased his turn radius by 292 feet to 1,684.  He is running in a larger circle, and his increase in speed is not enough to move his nose around faster in the larger circle: It is slower.  He is only turning 13.7 degrees per second now taking 26 seconds for a full turn.

Pilot ‘B’ is now gaining on pilot ‘A’ at a rate of 30 degrees per turn.

Pilot ‘A’ made the wrong choice.

[crutch]

Pilot ‘B’ slows down to 225 IAS and increases his G-loading to 4 Gs.  This changes his turn numbers and he is now in a circle with a radius of 845 feet with a rate of 22.4 degrees per second, completing a circle in 16 seconds.

If pilot ‘A’ had not made any changes, then this would let pilot ‘B’ catch up to him in 1 and a half circles.

Pilot ‘B’ now has another problem - can he sustain the G-load and speed for the time needed to catch his opponent. 

This is where the Energy properties of those aircraft become extremely important.

Granted, the previous example was a very ideal one, but it serves to show the relationship of speed and turn rates.

How do you modify a turn without using speed or G-load?

One is offsetting the center of your turn from the center of the bandit’s turn.
Put a penny on top of a quarter.  The rim of the quarter is your turn circle and the bandit’s is the rim of the penny.  If the penny is centered over the quarter, you both are turning around the same axis, you will never be able to catch the bandit.   
If you slide the penny to the side so the rim of the penny touches the rim of the quarter, then for one very brief point your turn will match the bandit’s.
The downside of this is it is much easier for the bandit to adjust his turn center to get himself out of danger.

Another method is to tilt your turn so it is not in the same plane of motion as the bandit’s.  Using the quarter analogy again, tilt it at a 30 degree angle and hold the penny flat.
Gravity will change the shape of your turn from a pure circle to an egg shaped oval.  The fat part of the oval is on the lower side where you change your dive to a climb.
This will also pull in the sides of your turn. 
These changes may be enough for you to match the bandit’s flat turn at a couple of points.  This is NOT a stable configuration and will change as energy is lost and one pilot reacts to the other.

The last way to modify your turn is by your bank angle.  If you are banked less than 90 degree, relative to the plane of the circle, then you can increase the G-load used in the turn.
If the bandit is banked at 30 degrees and you can fly with a larger bank angle of 60 degrees, you can effectively pull more Gs in the turn.  You will suffer a lose in altitude as less of the G-load is used to provide lift.

The absolute guaranteed way to win a turn fight is not to get in one.

sorry, I think I killed the system with my first try.
theis is a sample from "Check Six" without the 'tables'

[crutch]

Sorry for the double thread, thought the first one didnt work.

[Plazus]

Interesting stuff. Where did you get this information?

[crutch]

Easy, I wrote it  

The full text is part of the book Check Six

basic application of physics.  real world will not meet those numbers of course because I didnt take drag into account.

[morfiend]

 Great imfo crutch.

 Now I have a place to send players to read why they got out turned by Xplane in Yplane.


 Hopefully some players will read this and a light will go on.

   

[JunkyII]

good stuff

[TequilaChaser]

Pilot ‘A’ thinks he can catch up to pilot ‘B’ by increasing his airspeed and he pushes his throttle to the stop, accelerating to 275 IAS. He is starting to black out at 3 Gs and he does not want to pull any more.

is that a typo?  gots to be

[onan]

Good job Crutch....

It's not all about riding the blackout and full throttle then?

[Wreked]

Thank you crutch - 

-my understanding is that given a set of changing vaiables you want to attain your "best" Corner Speed : ie the set of variables that let you get around that circle in the quickest time. Nice examples of how to do that by changing some of the angles/orientations. Made it quite clear.

I can remember seeing a list of Corner Speeds some years ago for a variety of AC. - your Check 6??

...cheers eh!

[james]

Just ordered it off amazon and will be able to read it tomorrow

[FLS]

If pilot A increases power while holding a 3G turn won't he increase his turn rate instead of speeding up?

[crutch]

If pilot A increases power while holding a 3G turn won't he increase his turn rate instead of speeding up?

no, and this is where most die in a turn fight.

at 250IAS and 3Gs he was in a circle of 1392 ft radius, turning at a rate of 15 degrees a second for a complete circle in 24 seconds.

at 275 IAS and 3 Gs the radius is pushed out to 1684 ft and even though his velocity IS faster, he has a much larger distance to travel. it reduces his turn rate to 13 degrees a second and a complete circle in 26 seconds.

if he had slowed down to 225IAS and held the 3 Gs he would hace reduced his circular path to 1127 ft, increased the turn rate and would be turning a circle in 21.5 seconds

the math is real and it might take running the numbers several times to see it but thats the simple but hard truth.

Gs have more effect in a turn than changing speeds.

bottom line is the easiest way to win a turn fight is to not get in one

[FLS]

I understand your point and I'm not arguing that. My point is that airplanes typically don't speed up when you add power, they climb. If you consider a turn to be a horizontal climb then you can see where adding power while maintaining G would increase the turn rate not the speed.