Corsair Turning Ability in AH

[Knegel]

Thanks brooke for this nice article,

i found this in your article, when reading about sustained turns:


"However, note that max turn rate is lower than for flaps up"

".......dropping full flaps tends to slightly decrease maximum turn rate"

Nothing more and nothing less is my point!!

Also the F2A turn tests confirm this and the turnratio lost with full flaps is 30% in that case, while the radius just get reduced by 20%.

You conclusion, that a plane turn more tight with flaps, dont work always in a sustained turn, or only count if we dont consider the engine thrust.

As the F2A test show, in high alt, where the plane have much less power, the plane have the most tight turn without flaps and also the best turn ratio. Simply cause the drag eat the thrust, while the lift is needed to overcome the -1g, so the plane only can reach a rather smal bank angle with full flaps, resulting in a worse turn radius.


dtango,

although a plane while a steady climb dont perform a turn, the same forces, which would perform a turn right away, only by banking the plane, work. If i trim a plane into a steady  climb, and if you then bank the plane, the plane will turn(and lose altitude).
With other words, the plane itself produce the same forces while turning and climbing, they only seems to work different.  Actually we could say, climbing is special kind of turning.  btw, the speed to archive the best turn ratio is very similar to the best climb speed.  
If i increase the lift of a plane, without to increase the drag, the plane will have a better climb performence and better turn.

If i increase the drag, the climb ratio will decrease, but also the turn ratioin a sustained turn(like brooks article confirm) and since the turn ratio decrease(the plane is forced to fly with a smaler bank angle) the radius increase, despite the lift is the same.

While flying with full flaps, we increase the lift, but also the drag, so in a sustained turn and climb the ratios get decreased, how much the radius get influenced while a sustained turn depends to the available thrust.

Greetings,

Knegel

[dtango]

With other words, the plane itself produce the same forces while turning and climbing, they only seems to work different. Actually we could say, climbing is special kind of turning.

Nope, I disagree .  Until we agree on this concept then all the other discussion is for not I'm afraid because the physics of flight and all the derived equations around turns and climbs come from the concept that a turn and a steady climb are not the same.

Tango, XO
412th FS Braunco Mustangs

[Knegel]

Hi,

they are not exactly the same, but the forces produced by the plane are the same.
A steady climb is the same like a 1G turn, if no gravity would exist.

Its only more sencefull to describe the climb with the drag and trust, cause the needed lift to overcome 1G is always the same in a steady climb, but the lift influence the climb angle, so the lift isnt unimportant.


The climb and turn ratio get influenced by the ability to produce more lift over the smaler needed AoA to produce the same lift, so over the induced drag.
The climb angle and turn radius get influenced by the max lift and effective thrust(thrust force  minus drag froce).

Thats why the behaviour of the AH planes cant be realistic.

They cant lose climb ratio like mad with full flaps, but the same turn ratio remain.
In the 100mph example the plane without flaps fly in its most bad condition regarding its induced drag(max AoA) and no matter with what speed the "full flaps plane" fly, it always lose at least 30% of the climb ratio.

The high lost in climb ratio, cause using full flaps,  indicate a much increased drag, as result the turn rate, at same speed must decrease as well, but it dont.

The F2A test confirm this, same like Brookes calculation.

If you can explain why the F2A test show a so much different picture to the AH planes, it could help. Even the A6m2 and Ya9T, which are two of the few planes that realy lose turn ratio and dont gain that much regarding the radius, are by far better than the F2A in the test.

In BW, in IL-2, in EAW, in the MS flight simulator and CFSII the flaps similar results like the tested F2A flaps, so you can go on to try to explain why the AH flaps work ok, or you can start to try to find out if something is wrong.

Who did say this??
A scientist tend to find what he want to find.

Greetings,

Knegel

[dtango]

A steady climb is the same like a 1G turn, if no gravity would exist.

Nope it is not .  If no gravity existed, a continuous 1G lift force would result in steady loop NOT a steady climb.  This is the salient point that the rest of the discussion hinges on.

If I get a chance later, I'll post some free-body diagrams and equations to demonstrate.

Tango, XO
412th FS Braunco Mustangs

[dtango]

Here are some diagrams.  Equations to come later.

Based on Newton’s laws, if a force constantly acts perpendicular to the path of a moving object, the object will move in a circular path at constant speed.  The following diagram graphically depicts this.  This is fundamental physics.



Guess what?  Lift is a force perpendicular to the path of a moving airplane.  If you remove gravity as you suggest and you have a 1G lift force, the 1G lift force constantly acts perpendicular to the airplane.  The next diagram depicts the results.



Look familiar?  By Newton’s laws the perpendicular lift force to the motion of the airplane causes the airplane to move in a circular path, not a steady inclined climb.  

Add gravity and therefore weight back into the equation.  If L > W then you still get a curved (actually an egg-shaped) path not a steady inclined climb in a straight path.

In a steady climb there is no net force acting perpendicular to the motion of the airplane because Lift and the component of Weight opposing it cancel each other out.  That’s why a steady climb isn’t a 1G turn.

Tango, XO
412th FS Braunco Mustangs

[mtnman]

Knegel, you seem to be using the terms "turn radius" and "turn ratio" interchangably.  

Radius measures the SIZE of the circle-  Ratio measures the TIME needed to complete a 360 degree circle.  Those two circles will not be the same size if the best results are wanted.

A plane turning its best RADIUS circle will probably be turning its smallest radius circle by flying at or near minimum controllable airspeed.  Any excess speed would make the RADIUS larger, counter-productive to measuring for smallest RADIUS.

A plane flying for best turn RATIO is trying for the highest degrees per second around a circle.  This plane would do best (I believe) by flying at "corner velocity".  In the F4U, I understand this to be about 250 mph, which is well above minimum controllable airspeed.  Any slower than corner velocity would take longer than needed to complete the circle.  Any greater speed should increase the distance traveled...

A plane trying for best turn RATIO would NOT want flaps, but would want to be very near the speed where flaps would help.  A plane trying for best RADIUS would want to be slow, and would want / need flaps to have the extra lift provided to stay aloft for this slow, tight turn.

A plane flying slow enough for a small radius turn would find excessive bank to be detrimental, so would not want/need a whole lot of aileron.  SOME bank is needed of course, but too much aileron would probably cause problems with adverse yaw effect.  Rudder would seem to be more important, which the plane in question has lots of.  Rudder in this situation would supply the needed bank to complete the turn.

Brookes statement-

"However, note that max turn rate is lower than for flaps up"
".......dropping full flaps tends to slightly decrease maximum turn rate"  

-would be seen to hold water- turn RATE may suffer from flaps, but RADIUS would suffer from LACK of flaps.  Drag induced by flaps during a timed competition would be bad,  but would be acceptable if the competition was NOT based on TIME.
 
Two planes flying identical RADIUS turns (the charts you posted at the beginning of this discussion measured radius, not rate) would not have the same turn RATE if one was flying faster than the other.

If your lift/drag/thrust/climb/turn at 1G argument where true, what happens if the plane is flying level at 1G?  

You seem to argue that lift fights drag, and that lift also fights gravity.  I think the basic idea is that lift fights gravity, and thrust fights drag.  Drag does not necessarily hinder lift.  It could be argued that drag PROVIDES lift, or IS lift- at least until it gets excessive.

"A steady climb is the same like a 1G turn, if no gravity would exist."

If gravity didn't exist we would be having this discussion, for a whole LOT of reasons.

The plane climbing at 1G is using excess THRUST to CLIMB, not lift.  The plane in a 1G turn is using excess thrust to provide SPEED translated to LIFT to keep it aloft for the turn.  The energy is not used the same way.  

MtnMan

[Knegel]

Originally posted by dtango
Nope it is not .  If no gravity existed, a continuous 1G lift force would result in steady loop NOT a steady climb.  This is the salient point that the rest of the discussion hinges on.

Tango, XO
412th FS Braunco Mustangs

Thats exactly what i say, cause a loop in a room without gravity is nothing more than a turn, of course a turn without bank(no need to bank without gravity), but the plane turn and this show that the forces are exact the same, while in the case of a steady climb the gravity hinder the plane to turn.

A plane with more lift but same drag, weight and thrust will have less drag at the end, cause a smaler AoA is needed to produce lift to overcome 1G, as result, the lift need to get reduced(otherwise the plane would start to loop) and so the induced drag get reduced and the climbratio increase.
If the AoA dont get adjusted, the plane with more lift start to loop, then it will decrease the speed, so the lift reduce, but also the zero drag, at the end the plane will have a more steep climb and only a bit better climb than the one with less lift (Edit: Its rather the ability to produce lift (lift factor CL) than the lift itself where iam talking about).  

Of course we can also simply say the plane climb better cause it have a smaler drag, and this of course is enough for calculations regarding every steady climb at best climb speed, but we shouldnt forget why the plane have less drag. The reason is the better CL.


Greetings,

Knegel

[Knegel]

Hi,

Originally posted by mtnman
Knegel, you seem to be using the terms "turn radius" and "turn ratio" interchangably.  
MtnMan

I dont use it interchangeable, i only try to point out that the relation between turnratio and turn radius of most AH planes with/without flaps is unrealistic.

Originally posted by mtnman
A plane trying for best turn RATIO would NOT want flaps, but would want to be very near the speed where flaps would help.

As the turn radius AND turn rate tests made by me and posted by me in this theatre show, the AH F4U dont lose turn ratio with full flaps, thats what i criticize.

Originally posted by mtnman

 A plane trying for best RADIUS would want to be slow, and would want / need flaps to have the extra lift provided to stay aloft for this slow, tight turn.

In the F2A (Brewster Buffalow) test of a real plane(i posted the link to this test here), you can see that it depends to the powerload and air density, if the radius with flaps is smaler.

Originally posted by mtnman
A plane flying slow enough for a small radius turn would find excessive bank to be detrimental, so would not want/need a whole lot of aileron.  SOME bank is needed of course, but too much aileron would probably cause problems with adverse yaw effect.  Rudder would seem to be more important, which the plane in question has lots of.  Rudder in this situation would supply the needed bank to complete the turn.

The possible bank angle depends to the effective thrust, and the radius depends in big degree to the bank angle. Thats why the F2A in low alt with full flaps perform a 20% smaler radius than without flaps(better thrust cause more power and more air density), while the radius in high alt increase while flying with flaps.  Otherwise i agree and thats some more arguments why a turn at very slow speed isnt that good.
In all cases the turn ratio of the tested and calculated  F2A while a sustained turn decrease.
 
 

Originally posted by mtnman

......................... (the charts you posted at the beginning of this discussion measured radius, not rate) .................

I did offer turn rate and turn radius results later in this theatre.

Originally posted by mtnman
You seem to argue that lift fights drag, and that lift also fights gravity.

I just saw that its rather the lift factor where iam talking about and the lift factor is responsible for the induced drag.

Originally posted by mtnman

  I think the basic idea is that lift fights gravity, and thrust fights drag.  Drag does not necessarily hinder lift.  It could be argued that drag PROVIDES lift, or IS lift- at least until it gets excessive.

The idea is that the ability to produce lift influence the drag, afterward the thrust fights the drag.

Originally posted by mtnman

The plane climbing at 1G is using excess THRUST to CLIMB, not lift.  The plane in a 1G turn is using excess thrust to provide SPEED translated to LIFT to keep it aloft for the turn.  The energy is not used the same way.  

MtnMan

btw, while climbing with a very high AoA, the wing need to produce less lift than 1G, cause the propeller already point upward.
While climbing with full flaps at rather high speed the wing often need to produce more than 1G lift, cause the nose tend to point downward while a steady climb.

But anyway, this all is absolutly not important to value the AH turn performence with/without flaps, while a sustained turn.

Greetings,

Knegel

[Badboy]

Originally posted by Brooke
If by some miracle someone actually goes through the math of it, if you find errors, please let me know.

One big one and a couple of little ones...  check your mail.

Badboy

[Knegel]

Originally posted by Knegel

btw, while climbing with a very high AoA, the wing need to produce less lift than 1G, cause the propeller already point upward.
While climbing with full flaps at rather high speed the wing often need to produce more than 1G lift, cause the nose tend to point downward while a steady climb.

But anyway, this all is absolutly not important to value the AH turn performence with/without flaps, while a sustained turn.

Greetings,

Knegel

I just see that this is also a reason why a plane with flaps cant have a that good turn ratio and radius. With flaps the max AoA get reduced and the angle between the wing and the fuselage change. As result planes with flaps tend to have a "nose down" behaviour while a steady flight(this is wanted to provide a better sight while landing).
While a turn with flaps this mean: The nose dont point as far inward as without flaps, the thrustline is worse  for turn and climb, so we have less thrust into turning/climbing direction and we need more lift to overcome this.

Greetings,

Knegel

[gripen]

Brooke,
Badboy might have allready noted this out but it seems that you assume the value of the e constant with and without flaps.  In practice the flaps also change the value of the e and you can see this by looking the  figure 5. in the F2A data (the value of the K gives the slope of the Cl^2/Cd line).That is also the point in dtango's argumentation.

Otherwise I found your notation difficult to read  because the most of  formulas are inside the text, a better idea would be separating all  the formulas  from the text.

[F4UDOA]

Gents,

A while ago someone was using a very basic calcualtion for circumferance based on flight speed. I cannot find it and I was wondering if someone could repost it if possible.

Knegal,

You are reffering to turn rate, turn radius and turn ratio. What are you using to determine turn ratio? Are you using Dean's formula for this? What is your definition of "Turn Ratio". Also how are you measuring turn rate?

Thanks

[Krusty]

F4uDOA, do you mean this:

Make compete revolutions several times to make sure your speed is the same, and time how long it takes to make one complete turn on the compass. Then take the speed you have.

Then you have the time it took to make a full circle, and you have the MPH, so do the math to figure out how far you went in that time (say, 20 seconds at 150mph) that gives you circumference. Then divide by pi to get turn radius (or is it diameter?).

That what you were thinking of?

[Knegel]

Originally posted by F4UDOA
Gents,

Knegal,

You are reffering to turn rate, turn radius and turn ratio. What are you using to determine turn ratio? Are you using Dean's formula for this? What is your definition of "Turn Ratio". Also how are you measuring turn rate?

Thanks

Hi,

i just got aware that there may be a different between turn ratio and turn rate(actually iam dont know if there is a different, cause i always thought thats two words for the same, so much to my english knowledge ), this both i did use interchangable, measured in °/sec or sec/360° .
So i meant always turn rate, sorry for the mess.

Greetings,

Knegel

[F4UDOA]

Krusty,

Thanks a bunch, I find myself out sourcing parts of my brain everyday. Pretty soon I will just sit in a chair all day with a name tag and drule.

Knegal,

No problem, you are doing fine, I just wasn't sure if you were using Dean's formula for turning or turn rates. I was getting confused:rolleyes: