Corner speed?

[FlyingPapy]

S!

I often read about the corner speed and managing your energy.

For the management, I suppose it is to keep the best and fastest speed.

But how do I determine the best speed and the corner speed of each aircraft.

I know that dog fighting is an art and a science... but I am still struggling and making no progress.

The AI are better than me and online my life expectancy is 3-4 min.

I like to fly ultra and expert, it is beautiful and challenging, I like it.

Any pointers on dog fighting?

 

S!

[PB0_Foxy]

here is good explanation :

http://en.wikipedia.org/wiki/Maneuvering_speed

[AndyJWest]

One important thing to understand is that corner speed (basically the highest speed at which you can make a full control deflection without risking structural damage) is not the same thing as the speed giving the best sustained turn rate.

[FlyingPapy]

S!   PBO_Foxy

 

Nice link, but for the planes we are flying what would be those speed.

 

S!  AndyJWest

 

And what would be these sustained speeds. Can we find diagram of that.

 

S!

Edited July 25, 2014 by FlyingPapy

[Gambit21]

The important thing to remember about corner speed is that it's a transient advantage - once you make that turn you're no longer at corner speed.

[69th_chuter]

My understanding is that ...

 

 ... maneuvering speed is the maximum speed full control deflection can be used without airframe damage and

 

 ... corner speed is the lowest speed at which destructive G can be reached before accelerated stall.

[Gambit21]

Corner speed is that speed which the aircraft attains it's maximum turn rate.

It has nothing to do with 'destructive G/stall'

[Matze81]

Corner Velocity is the MINIMUM airspeed at which maximum allowable g's can be obtained, thus resulting in the highest INSTANTANEOUS turn rate.

No fighter has enough power to sustain that airspeed while pulling max g's (maybe for a while by giving up altitude but obviously not indefinitely).

That means that this highest turn rate will only be achieved temporarily and that it'll decrease quickly once the airspeed decreases.

In addition to Corner velocity a pilot needs to know another airspeed value / airspeed range. And that is the speed (range) that results in the highest SUSTAINED turn rate.

Basically it's the most g's that can be sustained without losing airspeed (or maybe better: energy).

 

So, in a classic 2 circle rate fight (in Sim forums you often read "Turn and burn" TnB) you maximize your turn performance by starting out with corner velocity and by pulling as hard as possible (within structural limits) initially. Once the airspeed has decreased to the airspeed for maximum sustained turn rate, ease off the backstick pressure slightly and hold that airspeed.

 

But obviously there's way more to BFM and ACM than having a theoretical understanding of those speeds. Knowing the basics and adhering to those speeds will not make you "Über"! Depending on the tactics that are employed, they might not even be that relevant (e.g. BnZ). Just keep that in mind! But in quite a lot of situations they can be useful.

 

So what are the speeds for our fighters in BoS?

Bad news: I don't know for sure!

 

I go by my subjective feel and estimate that corner velocity for the 109's could be around 450-480 kph.

The highest sustained turn rate is achieved around 290-300 kph, in my estimate.

 

I might be quite a bit off, so don't take it as fact or historically proven data!

 

Others on the forum did some useful "flight testing" and posted the results. Take advantage of those numbers.

 

 

Just my 2 cents. That's what I soaked up back in days.

 

[Gambit21]

I think I'll put some into narrowing it down for the Yak - but I haven't worried too much about it since like I said (and you obviously know) the advantage is transient.

[Gort]

Corner Velocity is the MINIMUM airspeed at which maximum allowable g's can be obtained, thus resulting in the highest INSTANTANEOUS turn rate.

No fighter has enough power to sustain that airspeed while pulling max g's (maybe for a while by giving up altitude but obviously not indefinitely).

That means that this highest turn rate will only be achieved temporarily and that it'll decrease quickly once the airspeed decreases.

In addition to Corner velocity a pilot needs to know another airspeed value / airspeed range. And that is the speed (range) that results in the highest SUSTAINED turn rate.

Basically it's the most g's that can be sustained without losing airspeed (or maybe better: energy).

So, in a classic 2 circle rate fight (in Sim forums you often read "Turn and burn" TnB) you maximize your turn performance by starting out with corner velocity and by pulling as hard as possible (within structural limits) initially. Once the airspeed has decreased to the airspeed for maximum sustained turn rate, ease off the backstick pressure slightly and hold that airspeed.

But obviously there's way more to BFM and ACM than having a theoretical understanding of those speeds. Knowing the basics and adhering to those speeds will not make you "Über"! Depending on the tactics that are employed, they might not even be that relevant (e.g. BnZ). Just keep that in mind! But in quite a lot of situations they can be useful.

So what are the speeds for our fighters in BoS?

Bad news: I don't know for sure!

I go by my subjective feel and estimate that corner velocity for the 109's could be around 450-480 kph.

The highest sustained turn rate is achieved around 290-300 kph, in my estimate.

I might be quite a bit off, so don't take it as fact or historically proven data!

Others on the forum did some useful "flight testing" and posted the results. Take advantage of those numbers.

Just my 2 cents. That's what I soaked up back in days.

Pretty good description - you soaked up,some good gouge. "Corner velocity" is sort of an "official" slang term and is indeed the min speed that max structural G can be generated. This state results in the maximum turn rate. However, for a long time, jets have been able to sustain this velocity at medium to low altitudes in level flight (this is why fighter pilots have neck and back issues in later life ). Some the the current fighters can actually climb. Obviously, the lower the speed for a given G, the higher the turn rate.

 

Afterburners are a wonderful thing...

 

Due to a lack of thrust, the prop fighters can't sustain their max G. In the game without access to a G meter to telemetry, it will be difficult to determine. You could get pretty close using replay and a stop watch to determine turn rates, but you won't know exactly where you transition into over G or are doing structural damage. We can't measure max structural G in the sim, just ultimate load capability as evidenced by the wings falling off. This is a too abrupt of an indicator to be useful for our practical purpose.

 

I do wonder how the programmers obtained flight data, and if it is reflected in the sim. It was certainly tested in real life and reported.

Edited July 26, 2014 by Victory205

[RydnDirty]

I suspect what the OP is really after is the optimum speed for sustained turn. As that is more useful to us flying ww2 prop planes.  For the bf109 is would be around 300km/h or just over. 

The thing to remember is that you could pull harder on the stick until the plane is on the verge of stall but this would not improve the turn time or diameter.  Just relax a little pull as little as you need to, to out turn your opponent.

 

I remember when I started online fighting I assumed the best possible turn I could do was pulling as hard back on the stick until I was on the verge of stall but I looked at graphs of turn time v speed and realised that after a certain point pulling harder on the stick slows you down past your optimum speed and degrades turn performance.

 

Here is an interesting graph of IL2 1946 bf109f4 vs P39n1 turn time v speed

You can see that the bf109 has better turn performance at high and low speed but at just the right speed the P39 will out turn the bf109.

 

Edited July 26, 2014 by WillyZurmacht

[FlyingPapy]

S! everyone.

 

It is a bit clearer now and the graph from WillyZurmacht is great.

Where can we have these graphs for the planes in BOS?

Thanks

 

S!

Edited July 26, 2014 by FlyingPapy

[Madov]

It's interesting that the theoretical doesn't always match the real life practice. In the book 'Hurricane Combat, The Nine Lives of a Fighter Pilot' the author Wg Cdr K.W. Mackenzie describes how they would train in tight combat turning by pulling the stick back into the stomach and holding it there until one could feel the blackout coming on. In fact blacking out in training was considered  normal. These pilots  knew that the enemy fighter was fast but also had great confidence in the Hurricane's abilities.

Edited July 27, 2014 by MADOV

[Gort]

It's interesting that the theoretical doesn't always match the real life practice. In the book 'Hurricane Combat, The Nine Lives of a Fighter Pilot' the author Wg Cdr K.W. Mackenzie describes how they would train in tight combat turning by pulling the stick back into the stomach and holding it there until one could feel the blackout coming on. In fact blacking out in training was considered normal. These pilots knew that the enemy fighter was fast but also had great confidence in the Hurricane's abilities.

 

That probably references a situation where the aircraft starts with excess energy available, either airspeed or altitude. The sustained turn rates of the prop fighters are low enough G that I doubt that blackout would be an issue in a level turn.

 

Sustained level turn performance is academic, it's not something that you'd want to do a a matter of habit unless you enjoy being target practice, or just want to gather bogey's for your mates to engage.

 

If you don't know what to do, start a nose low turn into the enemy, bleeding down to, then sustaining the corner velocity. Most planes give buffet cues for different lift states, something difficult to duplicate in the sim. Normally such at run would be felt as light aerodynamic buffet.

 

The current and recent jets would sustain max G at corner velocity or above until they ran out of gas. At high altitude you start with a slightly nose low turn that will eventually become level or climbing at low altitude. The pilot strains and cries a lot. The props and early jets are extremely nose low and even then, can't sustain max G.

Edited July 27, 2014 by Victory205

[JG52*ErmarShell]

On 25.7.2014 at 8:37 PM, AndyJWest said:

One important thing to understand is that corner speed (basically the highest speed at which you can make a full control deflection without risking structural damage) is not the same thing as the speed giving the best sustained turn rate.

 

Sry, but this is plain wrong in every respect.

 

The corner speed is a BFM term which describes a given speed at wich the aircraft has its max. turn rate (°/min) at Gmax at this certain speed without bleeding energy, aka sustained turn (rate). Thus "corner speed" and the speed for the sutained turn rate are the same!

 

The speed of the max. turn rate at max G while still conserving energy = corner speed. (it has nothing to do with speeds which could lead to structural damages).

 

There's also a higher speed possible and hence a higher G-load but at the expense of bleeding energy during such turns aka "instantaneous turns", either flown constantly by unexperienced BFM pilots or shortly at the beginning/ entry window of the opponent's turn by BFM pilots (followed by reducing the speed till they have reached the plane's corner speed and thus turning - hopefully - faster than their opponents).

 

Instantaneous turns is what you described. That's the turn rate flown at any speed's possible Gmax (so, right before either the pilot or the plane's structures break) - there's no corner speed, the Gmax can be flown at any possible speed, since you will pull as many Gs as you can to max the turn rate while therefore losing lots of energy due to the high G-loads and bank angles.That's the difference. That's what you mean, but this is quite the opposite of sustained turns only flown and possible at corner speeds.  If you continue flying an instantaneous turn you'll most probably end up losing the fight when your opponent doesn't do the same mistake, while the sustained turn - know your corner speed! - can give you a huge advantage over everybody who don't know their plane's corner speeds.

 

Again, the sustained turn rate is defined and achieved by flying the plane's max. turn rate at max. G but only at a certain, a given airspeed (not at any speed as for the instantaneous turn rate), and this particular speed is the infamous corner speed, since faster or slower than this corner speed will be leading to loss of energy until your plane starts stalling.

 

The latter also being a rookie mistake, for they often don't know their planes' corner speeds and unsuspectingly exceed it -  or maybe even drop below it - at max G-loads no matter the speeds or the bank angles because they hope to achieve the fastest turn rates this way and hence pull more Gs to not lose altitude during their turns but therefore losing energy in return until the plane's energy is bled out to an extent that they eventually fall prey to their opponents. It might also happen when people mistake the one speed/turn rate with the other.

 

In the planes data sheet it's mentioned as the speed at which the plane performs best, e.g. for the Yak-1b it's:

 

Maximum performance turn at sea level: 19.0 s, at 270 km/h IAS.

Maximum performance turn at 3000 m: 24.1 s, at 270 km/h IAS.

 

https://il2sturmovik.gamepedia.com/Yak-1b

 

As you can see, it's not always the fastest turn, especially not at all altitudes, but it's always the best turn rate achieved without losing energy, a turn which can be  'sustained' forever - till you run out of fuel of course, while your described  speed, the unsustainable instantaneous turn speed, might give you a faster turn rate - at the beginning - but not in the long run. These turns can theoretically be flown up to 9 g's, the limit till the pilot passes out, aka G-LOC, or till the plane breaks - whatever might occur first. But these turn rates cannot be sustained. The clue is in the title 'sustained turn rate'.

Edited April 21, 2018 by -=[GIAP]=-JG52*ErmarShell*

[ZachariasX]

On 25.7.2014 at 8:30 PM, FlyingPapy said:

Any pointers on dog fighting?

It is a concept from the jet age basically. With prop planes it is far from trivial maintaining a suitably high speed. Also you have to take into account that depending on aircraft at corner speed controls are rather stiff already. You have to have a really fast and powerful aircraft to benefit from the concept of corner speed. For many of our purposes, comparing relative turn (as shown above) and roll times at given speed between aircraft makes more sense.

 

In a Gloster Gladiator, you don't fly at corner speed in a fight. In a Tempest, much more so. But keep in mind, without a g llimiter corner speed can be a dangerous speed range.

[[CPT]Crunch]

You can have all the corner speed you want, and still get beaten up by the guy who knows how to maneuver outside your plane.  It only works if the other guy is dumb enough to commit.

[AndyJWest]

1 hour ago, -=[GIAP]=-JG52*ErmarShell* said:

 

Sry, but this is plain wrong in every respect.

...

 

Wrong? Nope. Correct according to the actual definition of corner speed used by real pilots of actual aircraft, rather than armchair sim jockeys:

Quote

The intersection of the positive aerodynamic boundary (lift limit) and structural limit defines a speed that is crucial to fighter performance and equally important to P-51 flying. This is known as “corner velocity” or “maneuver speed”. At this airspeed, a fighter attains maximum instantaneous turn performance. At any airspeed below this speed, the airplane cannot be overstressed. It will stall before the limit load factor is reached. Above this speed, however, the aircraft can exceed the limit load factor before it stalls

http://www.warbirddepot.com/fighter_formation/documents/FFQP_Turn_Performance.pdf

 

 

[DD_Perfesser]

Lets try not to confuse the OP any more....

Never heard maneuver speed used much in combat discussions. Mostly for cruise in turbulent air.

I've always thought of “maneuver speed”  as the best speed to enter a fight. You can do anything with your controls without damage. If you start maneuvering and your speed drops below the max performance turn speed it's time to back off the G or get the nose down.

[AndyJWest]

The thing is, neither the terms 'corner speed' or 'maneuver speed' were used much (if at all) during WW2, at least as far as I've been able to ascertain. 'Maneuvering speed' is the term now used for the maximum speed at which full control deflection can be used without damage*. 'Corner speed' or 'corner velocity' are generally defined the at the same thing when actually explained, other than on simmer's forums, where some people seem to think it is another term for best sustained turn speed. It would be a darned sight simpler if people actually explained what they meant, rather than using vague terminology that can't be found in historical (or modern) sources.

 

If anyone has evidence to the contrary, i.e. a WW2 (or even modern) source from real-world aviation that defines 'corner speed' as 'best sustained turn speed', I'd like to see it.

 

* This isn't strictly correct. The actual definition for 'maneuvering speed' (VA) is more complex: "The structural design requirements do not cover multiple control inputs in one axis or control inputs in more than one axis at a time at any speed, even below VA"

http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFinalRule.nsf/0/395c3f064247018a862577b200495b5a!OpenDocument

Edited April 21, 2018 by AndyJWest

[busdriver]

6 hours ago, -=[GIAP]=-JG52*ErmarShell* said:

The corner speed is a BFM term which describes a given speed at wich the aircraft has its max. turn rate (°/min) at Gmax at this certain speed without bleeding energy, aka sustained turn (rate). Thus "corner speed" and the speed for the sutained turn rate are the same!

 

The speed of the max. turn rate at max G while still conserving energy = corner speed. (it has nothing to do with speeds which could lead to structural damages).

 

Not sure which military service awarded your wings...but I've got the charts and definitions that dispute your assertions, and to think the USAF let me teach BFM.

 

Edit: Had to scan some old reference material to share. Attached is a four page PDF taken from something called "the big red book" or more typically "Three dash one" back in the Jurassic era. There were individual specific volumes tailored to each fighter or attack airplane in the USAF. These four pages were in every volume. I was able to copy these four page because they were unclassified. You will find the next two definitions on pages 2 & 3 of the PDF.

 

The minimum velocity at which maximum G can be obtained is defined as "corner velocity." Below this speed, buffet or stall will be encountered; above this speed the structural limit will be encountered first. At the corner velocity, the airplane attains its highest rate of turn which is sometimes referred to as the "Quickest/Tightest Turn", since about this speed turn rate decreases and turn radius increases.

 

Sustained corner velocity is the speed at which a maximum sustained rate of turn can be achieved for a given power setting and is a function of thrust since it occurs where G is maximum attainable without an accompanying loss of speed and/or altitude (Ps = 0).

 

For the uninitiated, sustained corner velocity means you are pulling less than the airframe maximum G and flying faster than corner. Read the example of the F-4 in the PDF.

 

 

This graphic is from my UPT T-38 Applied Aerodynamic study guide.

 

 

Energy Maneuverability.PDF

 

 

 

 

Edited April 21, 2018 by busdriver

[gn728]

Just a heads up - if you're interested - Requiems' latest tutorial video is on this subject 

 

[[APAF]VR_Spartan85]

Requiems’ a god....his aerial combat vids have saved my ass countless times!

[busdriver]

41 minutes ago, spartan85 said:

Requiems’ a god....his aerial combat vids have saved my ass countless times!

 

Yes he is. 

[AndyJWest]

@ Busdriver: Interesting that the second diagram you've provides shows the velocity for best sustained turn rate as higher than the corner velocity. I think the opposite is usually true for WW2 piston-engined fighters? I suspect it is something to do with the differing thrust characteristics of props vs turbojets. Any comments?

[Wolferl_1791]

 

The good old Falcon 4.0 manual is still a fantastic reference. Here's an example of some good EM charts: page 48 http://download.high-g.net/files/Falcon_4_Manuals/f4_HFFM-manual.pdf

And the info about turning: page 199 http://download.high-g.net/files/Falcon_4_Manuals/f4_manual.pdf

 

What about IL2? Don't know, don't care, I always find my own solution to each developing problem. I've done thousands of AI duels, and realized that the only way to win is to understand the fundamentals, not to focus on specific values.

 

But, for a beginner, values are important to understanding those fundamentals, so your best tool to finding it is a test flight, not a book.

- Align yourself with a big landmark such as a town or a river.

- Slow down to a desired speed.

- Open radiators to max, push throttle to combat power and do a series of 10x 360 turns. Use a chronometer and then divide by 10 the final time.

- Focus on maintaining altitude and speed.

- Increase speed after each series in 10 kph increments.

 

This will give you sustainable turn time at each speed.

 

Repeat the whole thing but with flaps at various positions.

 

Make a mental note about how each speed affected your stability, your comfort, i.e. how easy the turn was for you to maintain. How "hard" were you pulling? How unstable was the aircraft? Did you have to use a lot of rudder? Did you hear any buffeting? Were you able to answer to your mom call, throw the dog a ball while doing it?

But you're not finished yet. Turn radius is just as important. It's proportional to speed/turntime. It allows you to turn inside your enemy and even if his turn time is half of yours, if you have a smaller turn radius he'll never be able to get guns on you (put an F16 against a Po2 in a pure G turn fight and see what happens). Use an Excel table to find the values. Don try to remember a specific speed, just notice how it reacts to changes in speeds overall.

 

So which is the best corner speed? Pick a favorite, frame it and hang it on a wall. You'll barely use it 1% of the times anyway.

 

(bogus values)

Now, let's say that the 109 has a turn time of 20 seconds at 270 kph, 21 seconds at 290 kph and 22 seconds at 330kph. Which is your best turn speed? Which is the one you should strive for in combat? If you said 270 kph you've basically shot yourself in the foot. The right answer is: 330kph. That's your "Green Alert" speed, you're still turning well, but you can react to the fight, maybe even GTFO if needed. Even if your 270kph enemy is gaining up on you, wait, observe. Just as he's rubbing his hands and passing your spidey sense line, go to "Yellow Alert", i.e. pull slightly more and drop your speed to 290-300 kph. You now had a slight burst of rate of turn that will make your enemy call you cheater. He'll be baffled and try to turn even harder. But he can't. Now he's at 260kph, same turn rate as you and running out of ideas. Yes, he might have shorter turn radius, but you can fix that with a slight yo-yo. Oh but now he can extend (maybe), so what? Go home. You're alive, he's alive, a moment of christian love in the middle of the Apocalypse.

 

 

 

 

 

 

[busdriver]

3 hours ago, AndyJWest said:

@ Busdriver: Interesting that the second diagram you've provides shows the velocity for best sustained turn rate as higher than the corner velocity. I think the opposite is usually true for WW2 piston-engined fighters? I suspect it is something to do with the differing thrust characteristics of props vs turbojets. Any comments?

 

Andy I'm afraid I don't have enough information to support a definitive statement one way or the other. I would have to look at their VN diagrams. My intuition tells me that power limited WW2 fighters are worse performers in terms of maintaining energy therefore their PS = 0 (spoken as P sub s) curve would put sustained corner velocity faster than corner. But I'm the first to admit that I could be totally wrong. I reckon I make this deduction based on the F-4 (a heavy airplane that always kept slowing down in a turn even in AB) versus the F-16 (an airplane with a wide speed range for corner/sustained corner). I'm not saying that proves anything, they're just exemplars I had experience with. 

 

When I look at this simple diagram...as an example of a piston driven airplane (or jet for that matter).

 

 

I have a hard time grasping where one might plot sustained corner velocity (or speed if your prefer) slower than corner/maneuvering speed. I would want to see the VN diagram.