[FIXED INTERNALLY] Wind not accounted for in flight model and display.

[The Falcon]

Corner speed is defined as the minimum airspeed at which the maximum allowable g can be generated.

Well thank you for clarifying. A table can also be made using CAS but it is better to use TAS. CAS is a calibrated speed, it depends on the density, etc. The TAS is not, therefore it is a point of reference, it is easier to understand how much altitude you can gain or lose in a fight because it is a "true speed"

[The Falcon]

And that's IAS/CAS. From an aerodynamic POV the aircraft doesn't care about TAS at all.

See what the problem is with separating things? from the perspective of the wings/control surfaces/lift/drag it's correct, but not for the flight as a whole. The TAS for the a/c matters!

[The Falcon]

Ok let me understand what you mean. Are you saying that, maintaining the same engine power, an aircraft with headwind 200kts and GS 0kts, vertically climbing is the same as another plane with tailwind 200kts and GS 400kts?

Yes, finally, he got it!

Sorry but make me understand. If in one case your mass is moving at a speed of 200kts and in the other case your mass i moving at 0kts, how can they ever have the same vertical climb?

[bbrz]

See what the problem is with separating things? from the perspective of the wings/control surfaces/lift/drag it's correct, but not for the flight as a whole. The TAS for the a/c matters!

And? You are talking the whole time about GS, not TAS!!!!

TAS and CAS are basically identical at S.L. and both are not related the groundspeed in any way.

[bbrz]

Sorry but make me understand. If in one case your mass is moving at a speed of 200kts and in the other case your mass i moving at 0kts, how can they ever have the same vertical climb?

Because energy has nothing to do with groundspeed! Only IAS/CAS/TAS/EAS.

 

Everyone in this thread is trying since many pages to explain this fact to you. I'm running out of ideas in which other way I could make you understand this very basic fact. Sorry.

[takamba]

Sorry but make me understand. If in one case your mass is moving at a speed of 200kts and in the other case your mass i moving at 0kts, how can they ever have the same vertical climb?

 

Kinetic energy of an aircraft is a function of its airspeed, not ground speed.

We are in an aircraft moving through the air, we are not in a vacuum.

 

And IAS is in both cases 200 kts.

[Deano87]

Sorry but make me understand. If in one case your mass is moving at a speed of 200kts and in the other case your mass i moving at 0kts, how can they ever have the same vertical climb?

 

Stop using the ground as your reference. Why do you think the ground has anything to do with this? All that matters is airspeed. Moving mass (energy) is relative not absolute. Remember the earth is spinning at nearly 1000mph at the equator, should that velocity also increase the aircrafts energy state? It is after all measurable motion? The obvious answer is no. Aircraft flying with the rotation of the earth at the equator don’t pull to their vertical and suddenly shoot up at 1000mph lol. Why?

 

Energy state is in relation to the air the aircraft is flying through, it has nothing to do with the ground.

 

When an aircraft is flying downwind and it pulls to the vertical that downwind velocity DOES NOT get added to the vertical velocity.

[David OC]

We have all tried.

 

One more,

 

When you look at a flying plane once it's off the ground.

 

It's not going anywhere, "just a free", "scenic flight".

 

So no navigation need and he/she doesn't care where they end up.

 

Just pretend after this aircraft leaves the ground, the ground is no longer there (Forget Ground Totally). Only the aircraft in this air mass, it doesn't matter if moving around or still air mass.

 

The aircraft flies around in this air left, right, forward, back, up and down. It has no sense of anything but flying through this air mass. To the aircraft there is only perhaps some turbulent air to hit it this air mass.

 

There is no wind to be felt on the aircraft at all once flying. Only it's generated speed by it's own engine power.

(The is no relation ship to this "wind" when just flying around and having fun)

 

ONLY when you need to go somewhere or land does this matter and (ONLY AFFECTS TIME) not the flight model. Jetliners even use the jet stream to go somewhere even quicker. This doesn't affect the flight model.

 

Quote

"Airspeed and ground speed are not the same thing though. An aircraft can be flying within normal design limits, well below the speed of sound at altitude, but according to its ground speed, appear to be flying at near-supersonic speeds."

 

https://blog.privatefly.com/how-does-the-jet-stream-affect-my-flight-time

 

Does a pilot in a 777 need to worry about this ground speed that's faster than the design limits of the 777? Might rip the wings off turning out of this wind?;)

 

A good example of something that gives relative meaning to "wind"?

 

Airfield windsock

 

 

Why?

Because it's FIXED to a point in the earth.

 

Planes don't have a long enough keel when flying over water.:)

Edited February 4, 2020 by David OC

[billeinstein]

This doesn't make much sense IMO in your mentioned combat scenario. Furthermore if both aircraft are at roughly the same altitude, TAS will be the same for both at the same IAS. So what would be the point to know TAS?

Especially when maneuvering close to, or at the edge of the envelope, I'm much more interested in IAS than in TAS.

 

TAS * flight time = the length of flight path.

TAS^2/radius = |vector {G + gravity}|

 

That's the performance.

[bbrz]

TAS * flight time = the length of flight path.

TAS^2/radius = |vector {G + gravity}| That's the performance.

Maybe times have changed over the years. When we did 1 vs 1 and 2 vs 2 dogfights IRL we certainly didn't use the above formulae.

Without any AoA gauge the only important things were our eyes and IAS.

 

This additional TAS/performance thing doesn't do anything to help clarify things in this thread and for The Falcon in particular.

[billeinstein]

Maybe times have changed over the years. When we did 1 vs 1 and 2 vs 2 dogfights IRL we certainly didn't use the above formulae.

Without any AoA gauge the only important things were our eyes and IAS.

 

This additional TAS/performance thing doesn't do anything to help clarify things in this thread and for The Falcon in particular.

 

For example, for turn radius, TAS and G, you can get one of them with two others are known. IAS can't. If you don't care how tight your turn is, you don't need TAS.

[bbrz]

If you don't care how tight your turn is, you don't need TAS.

If you insist on calculating your turn radius precisely during a dogfight, for whatever reason, knowing the ground speed and the wind direction would be essential as well.

[billeinstein]

If you insist on calculating your turn radius precisely during a dogfight, for whatever reason, knowing the ground speed and the wind direction would be essential as well.

 

No. For a steady turn in constant wind condition, the turn radius is always changing looking from the ground (navigation flight path). But for the aircrafte perfomance caculation, you ARE flying in a circle with constant turn radius.

[Deano87]

For example, for turn radius, TAS and G, you can get one of them with two others are known. IAS can't. If you don't care how tight your turn is, you don't need TAS.

 

In ACM You don’t actually care exactly how tight your turn is, you care that you’re max performing the aircraft, and when it comes to that TAS is pretty meaningless, IAS and AoA are much more useful measurements. Corner speed and best sustained turn airspeed are both usually quantified in IAS not TAS.

[bbrz]

But for the aircrafte perfomance caculation, you ARE flying in a circle with constant turn radius.

Thanx, I know. It was you who mentioned BFM in this context. If you start using the E6B during BFM for precision you need to take everything into account.

[billeinstein]

In ACM You don’t actually care exactly how tight your turn is, you care that you’re max performing the aircraft, and when it comes to that TAS is pretty meaningless, IAS and AoA are much more useful measurements. Corner speed and best sustained turn airspeed are both usually quantified in IAS not TAS.

 

But your energy management must use TAS. Max rate turn is only one case in ACM. IAS tell you how to get max turn rate, TAS tells you how Max the turn rate can be. The radius doed affect the head to head dogfight for example, to chose one cirlcle fight or two circle, or how to keep your seperation and to pull how many leading turn.

[bbrz]

But your energy management must use TAS. Max rate turn is only one case in ACM. IAS tell you how to get max turn rate, TAS tells you how Max the turn rate can be. The radius doed affect the head to head dogfight for example, to chose one cirlcle fight or two circle, or how to keep your seperation and to pull how many leading turn.

Again, once an opponent is added to the equation we are talking about position/navigation, you would 'theoretically' need to know GS and wind direction. Otherwise your whole 'calculation' will be wrong.

[billeinstein]

Again, once an opponent is added to the equation we are talking about position/navigation, you would 'theoretically' need to know GS and wind direction. Otherwise your whole 'calculation' will be wrong.

 

No, there is no need for GS and wind caculation in ACM. Only A2G aimming need those correction.

There is no different for whether the air is moving (wind) or the ground is moving reversely.

[bbrz]

No, there is no need for GS and wind caculation in ACM.

Exactly, but then we are talking about IAS again and not TAS.

 

Since the wind is usually blowing in only one direction and you and your opponent are hopefully not flying in formation, you turn radius and lead angle calculation will be incorrect without GS and wind direction.

 

Since this is way off topic and it's unfortunately very similar to the discussion with The Falcon, I'll let you guys continue this never ending thread on your own.

[billeinstein]

Exactly, but then we are talking about IAS again and not TAS.

 

Since the wind is usually blowing in only one direction and you and your opponent are hopefully not flying in formation, you turn radius and lead angle calculation will be incorrect without GS and wind direction.

 

Since this is way off topic and it's unfortunately very similar to the discussion with The Falcon, I'll let you guys continue this never ending thread on your own.

 

The calculation can be done perfectly without GS and wind, but only TAS. The air of steady wind is an inertial reference system.

[sLYFa]

The calculation can be done perfectly without GS and wind, but only TAS. The air of steady wind is an inertial reference system.

Turn performance depends on a lot more then just TAS. Weight, drag, pressure and a lot of other factors play into the equation to account for all the forces in play. For the aerodynamical forces (i.e. lift and drag), IAS and Mach number are the important values and they are also the values presented to the pilot in the cockpit. They are therefore the ones provided (among other things) in aircraft performance charts. Of course there are exceptions, like cruise performance data where TAS is important for navigational purposes. But mostly, IAS and Mach are used.

[billeinstein]

For another example, your aircraft is in steady level turn in steady wind.

Your IAS is 300 kts, you are pulling 3 G in the turn. Wind speed is 50 kts.

You can't calculate your turn rate or turn radius with these information.

But if you know your TAS, for example is 350 kts, you can calculate them with it and get your turn rate is 8.82 deg/s, turn radius is 1170 m.

[bbrz]

...if you know your TAS, for example is 350 kts, you can calculate them with it and get your turn rate is 8.82 deg/s, turn radius is 1170 m.

NO! How on earth do you calculate the turn radius without knowing the wind direction?!?

[billeinstein]

Turn performance depends on a lot more then just TAS. Weight, drag, pressure and a lot of other factors play into the equation to account for all the forces in play. For the aerodynamical forces (i.e. lift and drag), IAS and Mach number are the important values and they are also the values presented to the pilot in the cockpit. They are therefore the ones provided (among other things) in aircraft performance charts. Of course there are exceptions, like cruise performance data where TAS is important for navigational purposes. But mostly, IAS and Mach are used.

 

That's dynamics. The mesuring the perfomance of an aircraft mostly means kinematics.

[bbrz]

You can't calculate your turn rate or turn radius with these information.

And how is it possible that the performance section of the manuals can do that with IAS?