corner velocity

[df54]

best     instantaneous turn rate occours at corner velocity doesn't it.?If im
reading em diagrams correctly it does. I really dont see the importance of corner velocity if you can't maintain it.

[humble]

thats a big part of hi/low yoyo's....you cant maintain it (nor would you want to) for long. The goal is to be able to hit the "bingo" number when your evading or saddling up. Flying any plane in a circle for any other purpose just gets you killed more often then not....

[GunnerCAF]

The aircraft will be most manoverable at the corner velocity.  It will most likely not be able to maintain that speed in a sustained turn, but it gives you an indication on what speed you should be flying when you are fighting.

As an example, An FW190 D9 with a corner velocity of 325, against a Huricane with a corner velocity of 200.  The Huri will be most manoverable at speeds around 200, and the D9 will be at its peak at 325.  If your in the D9, I would stay fast

Gunner

[Mace2004]

Corner gives you a combination of the best turn rate and the minimum turn radius.  At any speed above corner you're g limited and your radius increases because of the extra speed.  Below corner you're lift limited and the airplane will stall before you can reach the g required for best rate and radius.  You're right though, this is instantaneous turn rate, not sustained.  Before getting too wrapped up about sustained turn rates, remember that sustained turns are level turns (edit: I'm talking about test report sustained turn rates, this is the number a chart will give you), something typically avoided in a fight unless you're trapped on the deck in a lufberry.  

WWII fighters did not have sufficient power to sustain a turn at corner velocity with the nose level or above the horizon; however, nose low turns at corner can certainly be sustained, if only for the time the nose is low.  Fights are typically not stabilized at a single speed but instead are a series of transients.  Nose low accelerating to above corner, nose high decelerating to below corner.  By "centering" your fight speed around corner you're getting better average performance.

The principle in a fight is to recognize where you are in the envelope in relation to the absolute best performance your aircraft can give you.   For instance, let's say your corner velocity is 200mph.  You come over the top of a loop with 80 and start down on the back side.  Lots of guys will keep the throttle at max thinking the more speed they get with their nose down the better off they are.  If they're getting ready to bug they'd be right, but if they intend to continue a looping fight they should actually throttle back and aim for corner velocity across the bottom to get the nose around quicker and minimize the vertical turn radius.  

Let's say you're going nose down full bore and your speed builds to 300-350mph.  Your relative turn radius and rate are horrible and as you blast along trying to keep from blacking out and thinking how cool it is that you've got all this speed you've just overshot your target's turn circle and he's just going to rudder over above you and dive on you from behind your wingline.  Happens all the time.  

Here's another example.  You're at 500 ft nose down and 80 knots and you need to recover.  Do you A) throttle back to keep yourself from accelerating into the ground or B) firewall the throttle and hit wep?  The answer is B.  You need to get to your best turn rate and minimum turn radius, i.e., corner and you need to accelerate to get there.

Again, I'd say that most people understand that getting too slow can be a problem but the big thing to takeaway about corner is that many people make the mistake of being far too fast.  You think the extra speed is helping but it's not.  I love guys who want to hit the merge going 400 or 450 mph.  I'll hit the merge in a hurricane at about 300-325 and pull up and over hitting corner of 200 as I'm near the top of my loop.  This puts me well inside his turn circle and behind his wingline.  Since I'm just a bit below corner after coming over the top I just reverse, crank on a magic turn and I'm D200 dead six.  Happens all the time.

[df54]

great information mace just the info i was hunting for. In other words
i should stay at corner in vertical turns also(The advantages of staying at corner are much more obvious in flat turns). Therefore throttle management
is a major component of of vertical fighting. My throttle management in vertical turns is horrific so ineed to practice coming over the top at corner
and not getting to fast coming down.



ps    Please excuse mytyping skills.

 


   















 

how to tell if your a redneck(per jeff foxworthy)  You know your a redneck if taking out the trash means taking your in-laws out to dinner.

[Mace2004]

Originally posted by df54
great information mace just the info i was hunting for. In other words
i should stay at corner in vertical turns also(The advantages of staying at corner are much more obvious in flat turns). Therefore throttle management
is a major component of of vertical fighting. My throttle management in vertical turns is horrific so ineed to practice coming over the top at corner
and not getting to fast coming down.



ps    Please excuse mytyping skills.

Well, ideally, it would be best to be at corner for the whole loop but unless it's the first merge and you start well over corner you won't be at corner at the top of the loop.  The biggest part of a looping fight is to be at corner across the bottom. Over the top there are a few other factors that enter in.  If you're corner across the bottom, you're going to be much less at the top since props just don't have the power to overcome both the drag and G force so you're going to decelerate.  If you're very slow at the top your aircraft's pitch rate can enter in and pitch rate is different than turn rate.  Turn rate relates more to a steady state turn and your flight path while pitch rate is the ability to "point" your nose.  Let's say you're really slow as you reach the top.  You're inverted so it's important to be able to pull your nose down but when you're too slow the nose just doesn't like to move because you have less airflow and less elevator authority.  Rudder can be used but for a pure vertical loop dropping flaps does quite well.

[Murdr]

Originally posted by df54
great information mace just the info i was hunting for. In other words
i should stay at corner in vertical turns also(The advantages of staying at corner are much more obvious in flat turns). Therefore throttle management
is a major component of of vertical fighting. My throttle management in vertical turns is horrific so ineed to practice coming over the top at corner
and not getting to fast coming down.

The majority of the time you'll want full throttle in a loop fight.  You'll want the speed from the downsweep to carry you back to the top on the next upsweep.  If you are well above stall speed, you could adjust on the throttle when you are nose down, but be carefull you don't give up too much E while doing so.

At the top of your loop, its good to remember that most planes in AH will nose down like a rock when stalling inverted (some do have adverse torque forces that take over, and make them harder to manage).  If you are using flaps in this loop fight, and are inverted and near stall at the top, you can simply raise flaps (which raises stall speed) briefly to induce a stall, and swing nose down quicker rather than languishing at the top of your loop.

  If you are very near stall speed, or stalling over the top it is usually better to stay at full throttle.  When you cut power in that situation you just make it longer (in distance and time) to recover level flight at the bottom.  If you feel like your downsweep is going to carry you outside your opponents turn, you can always try guiding to their "weak side" to force them to roll aginst their torque.  If they are near stall speed, they may not be able to roll to you as you briefly overshoot.


Another thing to remember is that you aren't obligated to try to follow your opponents flight path when they split-s.  If gaining too much speed on the way down is a concern, you can flatten out your turn (like 45 degrees off of vert for example) and reaquire their extended 6 as you get to the opposite end of the turn.

[Mace2004]

Originally posted by Murdr
The majority of the time you'll want full throttle in a loop fight.  You'll want the speed from the downsweep to carry you back to the top on the next upsweep.  If you are well above stall speed, you could adjust on the throttle when you are nose down, but be carefull you don't give up too much E while doing so.

This all depends on the speed of the loop being performed, the geometry of the fight and the acceleration rate of your aircraft.  Even in a high speed fight you'll want full throttle the majority of the loop, except on the downside if you're going to significantly exceed corner.  Many planes can do constant full throttle loops in a slow speed fight and hardly get near corner so overspeeding isn't the issue; however, this is not the case during the high e of the first few turns where a great many kills occur or during an e fight.

At the top of your loop, its good to remember that most planes in AH will nose down like a rock when stalling inverted (some do have adverse torque forces that take over, and make them harder to manage).  If you are using flaps in this loop fight, and are inverted and near stall at the top, you can simply raise flaps (which raises stall speed) briefly to induce a stall, and swing nose down quicker rather than languishing at the top of your loop.

I have to completely disagree with this.  Stalling over the top usually results in the nose parking.  It'll fall through eventually but in it's own time.  I'm not talking minutes here, just moments but those are very long moments in a fight.  It's much better to prevent the stall and point the nose where you want it.  People sometimes forget that when you're pulling positive G the lift is "up" only relative to your plane and when inverted over the top of a loop your lift vector is down.  Stalling and/or raising the flaps to induce a stall is exactly the wrong thing to do as it costs you your lift and eliminates your ability to generate G along with causing a large increase in drag.  You lose the ability to pull your nose back down and your airplane will do whatever it wants to do.  Eventually, what goes up must come down and this includes stalled airplanes and usually they'll just seek the vertical and the nose will drop through although sometimes, they'll hang and even do an inverted falling leaf.  Also, in a looping fight, it's best to raise your flaps when coming up on the frontside of the loop to reduce drag.  This is particularly important with two position flap systems like the spit and hurricane.  In either case, adding some flap over the top is the most effective way to prevent an inverted stall, maintain control and get your nose over and down again.

 If you are very near stall speed, or stalling over the top it is usually better to stay at full throttle.  When you cut power in that situation you just make it longer (in distance and time) to recover level flight at the bottom.  

True, I don't think anyone suggested cutting power at the top of a loop.

If you feel like your downsweep is going to carry you outside your opponents turn, you can always try guiding to their "weak side" to force them to roll aginst their torque.  If they are near stall speed, they may not be able to roll to you as you briefly overshoot.

This is a good point.  If you have to choose a side then go in the direction that's most difficult for him and, except for the Tempest and Typoon, that would be the right side.

Another thing to remember is that you aren't obligated to try to follow your opponents flight path when they split-s.  If gaining too much speed on the way down is a concern, you can flatten out your turn (like 45 degrees off of vert for example) and reaquire their extended 6 as you get to the opposite end of the turn.

Another good point.  You can take the fight into the oblique instead of pure vertical; however, just be aware that this usually results in a rolling scissors.  If you aircraft can't roll as well as your opposition you may be giving him an advantage but overall, it can be a very good move.

[Simaril]

THANKS for this discussion, Mace and Murdr! This has been a big conceptual help for me.

Now it'll only take a few weeks of being splatter on someone's windshield to get it into practice......

[Balsy]

where are accurate AH2 charts available that state cornering speed?

Thanks,

Balsy

[Widewing]

Originally posted by Balsy
where are accurate AH2 charts available that state cornering speed?

Thanks,

Balsy

Corner velocity can be roughly estimated for each type by doing a simple test.

Take off climb to at least 1,000 feet. Level off and accelerate to about 300 mph.

Pull into a turn, cranking in more G until your vision is limited to a small hole in the black... You are now at approximately the plane's corner velocity. If you open E6B and center the speed read out, you will be able to see IAS and TAS.

I've done this with the P-51D and F6F-5 and it is very close to published corner velocities for these fighters. It's a good rule of thumb at least.

Note that you will not be able to sustain corner velocity for more than a few seconds without turning nose down.

My regards,

Widewing

[Mace2004]

Originally posted by Balsy
where are accurate AH2 charts available that state cornering speed?

Thanks,

Balsy

What would really be nice are a complete set of V-n diagrams but WW is right the approximate number can be roughly determined using the method he mentions.  For the Hurri it's about 220mph at S/L with a combat load which is good enough for government work.  The few I've checked include the A6m5: 220, the 109F: 250, and F4U-1D:275.  All of these were at S/L and 50% fuel, no flaps.  

Funny thing happened when I was testing the F4U.  While accelerating out to 300 I fired a few bursts and firing the guns slowed the acceleration rate.  When I was around 300mph firing the guns stopped the acceleration completely.  When I stopped firing the airplane began accelerating again.  This is very noticable watching the E-6B.  I've heard that firing the 30mm cannon in the A-10 has an effect but six .50s?  Is AH modeling recoil or is something else going on?

[Widewing]

Originally posted by Mace2004

Funny thing happened when I was testing the F4U.  While accelerating out to 300 I fired a few bursts and firing the guns slowed the acceleration rate.  When I was around 300mph firing the guns stopped the acceleration completely.  When I stopped firing the airplane began accelerating again.  This is very noticable watching the E-6B.  I've heard that firing the 30mm cannon in the A-10 has an effect but six .50s?  Is AH modeling recoil or is something else going on?

Recently, I was testing climb rate in the F4U-4. I fired the guns while climbing and the climb rate dropped by about 1,000 ft/min! I guess they are modeling recoil.

My regards,

Widewing

[Mace2004]

Originally posted by Widewing
Recently, I was testing climb rate in the F4U-4. I fired the guns while climbing and the climb rate dropped by about 1,000 ft/min! I guess they are modeling recoil.

My regards,

Widewing

More cudos to HT.  If they're paying enough attention to the flight model to include these kinds of details it shows almost an obsession for accuracy.

[Murdr]

Originally posted by Mace2004
This all depends on the speed of the loop being performed, the geometry of the fight and the acceleration rate of your aircraft.  Even in a high speed fight you'll want full throttle the majority of the loop, except on the downside if you're going to significantly exceed corner.  Many planes can do constant full throttle loops in a slow speed fight and hardly get near corner so overspeeding isn't the issue; however, this is not the case during the high e of the first few turns where a great many kills occur or during an e fight.

Gee, I just said all that.  All I cautioned is not to go wholesale overboard on throttle chopping.  You have a number of issues to deal with besides your own corner velocity, including a match up between dissimilar planes.  If you are only focused on what you can you, it is going to put you in a disadvantage in some situations.

I have to completely disagree with this.  Stalling over the top usually results in the nose parking.  It'll fall through eventually but in it's own time.  I'm not talking minutes here, just moments but those are very long moments in a fight.

Again I added specific notes along with the suggestion that it is a better idea in some planes than it is in others.  "It'll fall through eventually but in it's own time."  With the point being "in its own time" can be quicker with the right plane model and attitude.  Even if the time is negligble, you could achieve a flight path that you otherwise could not.  Again noting that it was simply a possible option in a very specific situation, and not a general rule.

*I guess I should differentiate better between "something to experiment with" and "its a good idea to".  I do agree with mace to the extent that there are a number of planes where you would typically lose more than you would gain by stalling.*