Whats the best corner speed for the hornet?

Quote:“...getting the smallest radius as fast as you can.“

No sorry, thats not what you re doing with corner speed.You have to decide, you either get the best rate or the smallest radius, but not both.Its the pilot job to choose which is better suited to the scenario he is in.

You donˋ t have to believe me though.

Look it up in the US Navy training command (they should´ve some authority on the matter) Flight training instruction for the the t-45 strike training.( its openly and freely available on the web.)

It covers among other things Basic Aerodynamics in regards to max performing your aircraft during BFM. In section 4-3 / 4-4 ( basic aerodynamic review) they list some interesting speeds for max perf ( for the t-45 of course, but the point is transferable):

Corner speed is 420kts , but min radius band is 140-180 kts. You see, min radius speed is quite a bit lower. Let me know if you canˋt find the document.

If you re in a true 1c fight or in the flat scissors where you also want to minimize your radius and downrange travel, all the turn rate in the world may not be enough to save your a— if you re going too fast , because at one point you will be crossing in front of the bogeyˋs nose due to your bigger radius and if he is really good, that might be enough for you to end up as gun or IR fodder.

Kind regards, Snappy

...You may want to rethink this or dig deeper into aircraft turn radius formula.

Snappy.

Well, in fact that guy "000rick000" is generally right! Sorry, but you may need to rethink about what the turn radius formula says:

G = V^2/R, where G is obviously the centripetal acceleration, V is velocity and R is radius.

Indeed, the w (can't spell the conventionally used "omega" character for angular velocity), V and G have a linear interdependent function. These 3 all vary linearly to one another, while the R versus G varies with a squared function of V, but don't get fouled by looking only at the formulas and not look further on how the values: V, w and G can combine in order to (mathematically) have the same resulted R.

What is corner velocity first of all? It is the velocity at which you will obtain the plane's maximum allowed instantaneous lift force (structurally operational limited) divided by a given weight, otherwise known as a maximum operational Z-Gload, which will offer you the highest instantaneous angular velocity. This mostly happens when flying at the maximum aerodynamic lift coefficient which lies nowhere else than on stall AoA (be it taken as the wing's only stall AoA or supercritical (vortex shed on fuselage) AoA)! Well, the following factors will affect this dimensionless coefficient: 3D wing shape, 2D or airfoil sections shapes (affected by leading and/or trailing edge surfaces deflections), Mach number and Reynolds number.

You can make a test (by only using the formulas or in-game tests) and see that if you can mathematically hold the same max lift coefficient at, any given instantaneous test speed, the resultant G-load (any G within or outside the structural limitation), centripetal acceleration (which is G-load multiplied by the gravity acceleration constant 9.80665) and angular velocity "w" will in the end give you the same radius R. The reason why the Navy knows that their T-38 (or any airplane whatsoever) will obtain a lower turn radius at low airspeeds most probably has to do with increasing the maximum lift coefficient by the use of droops and flaps. There is no other physical way that the plane can obtain a much lower turn radius, unless it increases the maximum lift coefficient (be it aerodynamic or global).

For short, the maximum aerodynamic lift coefficient alone (not accounting engine thrust) will give you the same resultant radius (as long as the engine thrust isn't varied) no matter how the G-load and velocity will decrease throughout the turn (these usually decrease due to excessive drag).

Now, I've only taken into account an ideal situation where the maximum aero lift coef. won't vary with airspeed and Mach number. The airspeed affects the lift coef through the Reynolds number. The Mach number affects the critical AoA (thus the max aero lift coef) due to the disturbances of pressure waves (compressibility) and later due to the presence of normal/attached shock waves. In general, the maximum aero lift coefficient will have it's "maximum" somewhere near 0.25-0.35 (this drastically depends on wing shape). Above and below around Mach 0.3, the max aero lift coef will become lower (decreasing more rapidly towards lower Mach than it does towards critical Mach).

The thing is that engine thrust will always affect the actual (depends on actual AoA) and/or maximum global lift coefficient (which takes into account all the forces perpendicular to the undisrupted airflow vector, not just the aerodynamically gained ones). Due to the fact that as airspeed increases, so will the engine thrust also increase (more or less linearly), the max global lift coef may eventually get higher if somehow the max aero lift coef won't suffer a sufficient decrease, so theoretically/mathematically if you will, the radius should be getting even lower near corner velocity if the sum of aerodynamic + thrust induced lift force will eventually generate a higher max global lift coef than at lower airspeeds where the engine produces less thrust. But this is only theoretical! Usually this may never happen indeed, because for airspeeds as high as 400+ knots near corner velocity, the max aero lift coefficient is somewhat reduced due to high Mach number and the engine thrust component (through AoA) may not compensate for the loss, but anyway, the difference in minimum radius between corner velocity and minimum 1G flight speed at crit AoA should be barely noticeable.

In all the velocity corner and/or EM diagrams that we see, we are not told anything about the LE/TE (leading edge/trailing edge) surfaces deflections, but we can presume that at least the leading edge droops are partially deployed towards increasing the critical AoA (thus maximum aero lift coef) even though it's lower than near Mach 0.3. I doubt that near corner velocity, when pulling to obtain the critical AoA, the droops/slats wouldn't employ to "correct the airflow", otherwise I'm pretty sure that the corner velocity would've been much lower than we actually find them. This again can add up to tell that turn radius mustn't vary considerably from corner speed to low speed.

Kind regards.

Now, on the other hand has any of you actually tried to compare those EM diagrams that you found on the net with how the plane actually performs in DCS? Surprisingly, the DCS FA-18 will outperform the data from any EM charts found in both constant turn rates at any comparable IAS/Mach, altitude weight/loadout config and also in longitudinal acceleration (engine thrust), vertical climb and/or max climb rate!

Very good for finding the real EM diagrams, but please make some tests and compare them. What I've found is that our in game FA-18 has a constant turn rate of about 2-2.5 seconds faster than any of the presented diagrams. At higher loadouts and altitudes, the gap is even higher!

Kind regards!

...

Close to the same speed as the f-16 it seems, can she hold the same rate?

Do you find this normal?

Kind regards!

*snip*

If you break at corner speed pulling max G, at that instant you'll get your best instantaneous rate and you'll be very close to your smallest turn radius also, but ONLY at that instant.

You'll immediately start bleeding speed and your turn rate will start to fall off. You now have a choice: keep pulling to maintain minimum turn radius, or ease off the stick to keep your speed up for best sustained rate. You have to pick one, you don't get both. Just look at a turn performance chart.

If you break at corner speed pulling max G, at that instant you'll get your best instantaneous rate and you'll be very close to your smallest turn radius also, but ONLY at that instant.

 

You'll immediately start bleeding speed and your turn rate will start to fall off. You now have a choice: keep pulling to maintain minimum turn radius, or ease off the stick to keep your speed up for best sustained rate. You have to pick one, you don't get both. Just look at a turn performance chart.

Exactly man! You've just re-told what I've already explained from an engineering perspective! The turning radius is only a function of lift coefficient (if wing load (mass and reference area) and fluid density are already constants), while the turn rate is only a function of speed and centripetal acceleration (or G-load as reference).

Kind regards!

As windy said - it's all about knowing if your are in a 1C or 2C fight.

For 2C keep it between 350 and 450, for 1C pull until below 200 kn and then keep it between 20-22 alpha. That worked for me. An EM- diagram would be nice and there is always Tacview to generate our own numbers.

My advice: keep the tally and listen to the alpha. If you keep the tally and have the speed in the right ballpark, the fight is half won.

Sorry to revive an old thread but i was curious what you meant by keep the alpha between 20-22? What does that mean exactly? So if you're at 200kn then don't point your nose more than 20 degrees away from the direction you're traveling? Is that so you don't stall?

The alpha is the angle of attack and it's displayed in the HUD, indicated by an... well... Alpha.

The hornet can fly ridiculous AOSs without stalling. I think at about 20° at 200 KCAS you should be able to stay at this speed.

So it's less about stalling and more about conserving energy.

Sorry to revive an old thread but i was curious what you meant by keep the alpha between 20-22? What does that mean exactly? So if you're at 200kn then don't point your nose more than 20 degrees away from the direction you're traveling? Is that so you don't stall?

Look for the infinity symbol on the left side of the lower HUD data block. Think of AOA as how much the jet is "skidding" through the sky. At high AOA, the jet is actually skidding in relation to where the nose is pointed. The more AOA, the more the skid. IOW the actual flight vector path of the aircraft is something less than where the nose is pointed. The less AOA, the more the two are coincident.

Sorry to revive an old thread but i was curious what you meant by keep the alpha between 20-22?

It's a bit like slip angle in a car.

I used to switch half flaps for corner rate, but DCS changed (prob fixed) the ECS and that aint workin anymore.