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

[billeinstein]

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

 

Turn on the smoke during the turn and it will tell you why not count the wind.

[bbrz]

Turn on the smoke during the turn and it will tell you why not count the wind.

You honestly believe that the turn radii are identical when turning into a 100kts tailwind and into a 100kts headwind?

[billeinstein]

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

 

If you can do it with IAS, but more date must be needed such as tempreture and pressure. First convert the IAS to TAS with them, then calculate the rest.

[billeinstein]

You honestly believe that the turn radii are identical when turning into a 100kts tailwind and into a 100kts headwind?

 

Yes. It's a steady turn.

[bbrz]

If you can do it with IAS, but more date must be needed such as tempreture and pressure. First convert the IAS to TAS with them, then calculate the rest.

Sorry but that's plain and simple wrong. Have you even looked at turn performance tables?

[bbrz]

Yes. It's a steady turn.

Well, in this case any further discussion is definitely useless. I'm starting to believe that you and The Falcon are actually twins. Over and out.

[sLYFa]

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

 

These two are closely linked. How will you know your TAS or any speed if don't know thrust and drag? How will you know g-load if you don't know lift?

Your initial claim was:

CAS/IAS/EAS is mostly for dynamic/structural strength/load caculation, not performance.

That is simply not true. Basic geometry like turn radius equals g load and TAS is not aircraft performance, it's much more complicated as I already outlined.

I can assure you that most of the aircraft performance charts (which literally have the word 'performance' in their title) are not what you are describing.

 

Well, in this case any further discussion is definitely useless. I'm starting to believe that you and The Falcon are actually twins. Over and out.

Welcome to DCS forums, where arguments and opinions are sometimes the same...

[billeinstein]

Well, in this case any further discussion is definitely useless. I'm starting to believe that you and The Falcon are actually twins. Over and out.

 

Can you understand the steady turn is a constant radius turn? Wind just make the turn center move, not changing the radius. Just like a wheel rolling on the ground. Every point on it have a constant turn radius, but the center is moving forward.

[billeinstein]

These two are closely linked. How will you know your TAS or any speed if don't know thrust and drag? How will you know g-load if you don't know lift?

Your initial claim was:

 

That is simply not true. Basic geometry like turn radius equals g load and TAS is not aircraft performance, it's much more complicated as I already outlined.

I can assure you that most of the aircraft performance charts (which literally have the word 'performance' in their title) are not what you are describing.

 

 

Welcome to DCS forums, where arguments and opinions are sometimes the same...

 

The performance of an aircraft mainly are how fast and how high it can fly, how tight and how fast it can turn, and climb, etc. you will unlikely to see IAS in it.

[billeinstein]

Sorry but that's plain and simple wrong. Have you even looked at turn performance tables?

 

Do you know the Mach number is TAS/speed of the sound at that condition?

[sLYFa]

The performance of an aircraft mainly are how fast and how high it can fly, how tight and how fast it can turn, and climb, etc. you will unlikely to see IAS in it.

Good that you mention these parameters, because TAS is either irrelevant for them or they are much more conveniently conveyed with IAS.

 

I have seen a lot of aircraft manuals, both russian and western, military and civilian, including (admittedly small) AC I flew myself. And in almost every performance chart for TO/climb, descend, loiter/cruise and landing, IAS (or CAS) is used. And this is only logical because A: IAS is a major factor in calculating aerodynamical forces and B: it is known by the pilot at any time.

If you don't believe me, get yourself any aircraft performance manual and have a look.

[billeinstein]

Good that you mention these parameters, because TAS is either irrelevant for them or they are much more conveniently conveyed with IAS.

 

I have seen a lot of aircraft manuals, both russian and western, military and civilian, including (admittedly small) AC I flew myself. And in almost every performance chart for TO/climb, descend, loiter/cruise and landing, IAS (or CAS) is used. And this is only logical because A: IAS is a major factor in calculating aerodynamical forces and B: it is known by the pilot at any time.

If you don't believe me, get yourself any aircraft performance manual and have a look.

 

[billeinstein]

[sLYFa]

How convenient isn't it? Care to share something from the P-51's Pilots Flight Operating Instructions? Because it is full of IAS tables, just like NATOPS, Airbus FCOMs and most of the other manuals.

Anyway, I see this has turned into a 'look I'm right' discussion. I provided my arguments of why IAS is more interesting for performance charts than TAS. You can keep throwing archaic diagramms all you want, that doesn't change physics and how things are calculated. If you want to insist, so be it. I only hope that your translation work is more accurate than your research on aeronautical literature.

[Deano87]

I have never seen any aircrafts pilots notes, flight manuals or anything else that has listed critical speeds in TAS, its always IAS/CAS & Mach.

 

VNE limits are usually IAS/CAS and Mach whichever is reached first. Block 50 F-16 VNE is listed as 800KIAS/2.05M for instance.

Same for stall, manoeuvring, flap and gear limit speeds.

 

TAS has its place for flight planning and other things but it's not that relevant to a discussion about what a pilot actually uses while flying imho. I'd rather know how much G potential and energy the aircraft has then how quickly I'm actually traveling through the air tbh.

[billeinstein]

How convenient isn't it? Care to share something from the P-51's Pilots Flight Operating Instructions? Because it is full of IAS tables, just like NATOPS, Airbus FCOMs and most of the other manuals.

Anyway, I see this has turned into a 'look I'm right' discussion. I provided my arguments of why IAS is more interesting for performance charts than TAS. You can keep throwing archaic diagramms all you want, that doesn't change physics and how things are calculated. If you want to insist, so be it. I only hope that your translation work is more accurate than your research on aeronautical literature.

 

You know there is no TAS indicator on most early wwii fighters. But in every performance test charts from the test flight it was converted to TAS. Do you know why?

[billeinstein]

I have never seen any aircrafts pilots notes, flight manuals or anything else that has listed critical speeds in TAS, its always IAS/CAS & Mach.

 

VNE limits are usually IAS/CAS and Mach whichever is reached first. Block 50 F-16 VNE is listed as 800KIAS/2.05M for instance.

Same for stall, manoeuvring, flap and gear limit speeds.

 

TAS has its place for flight planning and other things but it's not that relevant to a discussion about what a pilot actually uses while flying imho. I'd rather know how much G potential and energy the aircraft has then how quickly I'm actually traveling through the air tbh.

 

For energy and G calculation , it must use TAS. Mach number is from TAS, not IAS.

[The Falcon]

Guys on the IAS TAS speech I would like to report one thing..

 

To obtain the TAS, the other speeds must be corrected by the errors:

 

IAS corrected by the position and instrument error gives the CAS;

CAS corrected by the compressibility error of the air gives the EAS;

EAS corrected by the density error due to the altitude gives the TAS;

TAS corrected by wind effects gives GS.

 

The TAS is important in the calculation of the energies, it is like a reference point. IAS indicates the speed relative to the mass of air, it does not correct the density, it does not tell you at what real speed the a/c is hit by the air. It only tells you what your "aerodynamic speed" is. TAS tells you absolutely how many meters per second the air hits you, not for nothing it is called true airspeed. In the absence of wind, the TAS and the GS are the same. So in the calculations it gives you the energy related to your displacement of your mass in the air. If I used IAS, the calculation would not be correct simply because IAS is not affected by the attitude of the aircraft, the change in density and air temperature with the altitude and the compressibility effects.

[The Falcon]

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.

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.

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.

This thing cheats my mind. I understand that the calculation of kinetic energy is relative to the observation point, but there are things that confuse me, I would say that it is not really a basic thing.

For example the discourse of the earth rotation. Why can't you add that energy vertically? I believe that by rotating together with the earth surface we have a certain kinetic energy and the bodies tend to conserve this motion energy. But if the earth stopped spinning we would fly away towards the direction in which the earth turned but also vertically. So in addition to having a kinetic energy we are in a system of forces. In this case we have the centrifugal and centripetal force, but gravity does not allow us to escape or to orbit, therefore our centrifugal force is not strong enough to escape.

 

And here comes the problem, what cheats me.

When you want to go into space and orbit you have to reach a certain speed to escape gravity and a speed to stay in orbit. This speed is not related to the airspeed but to the GS.

So if as you say the two a/c have the same vertical climb it is because you are using the airspeed. But the calculation is mathematically correct from the GS point of view only but it does not apply in reality because we should have a fleeting speed sufficient to convert our kinetic energy vertically.

I hope someone can prove mathematically so i'll have clearer ideas.

Just to clarify i'm using this formula

 

Kin.E= 1/2 m v2

This has nothing to do with the bug etc ... but it's nice to learn and understand things.

Edited February 5, 2020 by The Falcon

[Deano87]

For example the discourse of the earth rotation. Why can't you add that energy vertically?

 

Because the air its flying through is also traveling at 1000mph with the earth. So its lifting potential is ONLY the relative motion between it at the aircraft. Even as the aircraft is flying vertically upwards (compared to the ground below it) its still actually traveling at 1000mph sideways with the rotation of the earth. If it DID suddenly inherit the energy of the earths rotation you would have got free energy, because it would be climbing vertically at 1000mph (plus its original airspeed), but ALSO traveling sideways at 1000mph with the rotation of the earth. This is exactly what happens with tailwinds and headwinds.

 

This leads me to the question, IF pulling to the vertical would add energy from downwind (it doesn't but lets imagine), then why not turning 90 degrees left or right (crosswind), What would the difference be? Surely that would also add energy as well, the same physics are happening, only 90 degrees different. Think about why that doesn't happen when turning crosswind, and you get your answer as to why it doesn't happen when pulling to the vertical.

 

 

And here comes the problem, what cheats me.

When you want to go into space and orbit you have to reach a certain speed to escape gravity and a speed to stay in orbit. This speed is not related to the airspeed but to the GS.

So if as you say the two a/c have the same vertical climb it is because you are using the airspeed. But the calculation is mathematically correct from the GS point of view only but it does not apply in reality because we should have a fleeting speed sufficient to convert our kinetic energy vertically.

 

Well an orbital velocity is not really related to ground speed either. Say you orbit your space craft around the equator but in the opposite direction to the earths spin, your GS would be +2000 mph faster then it would be orbiting with the earths spin, but your orbital velocity compared to the solar system would be the same. Once in space the ship doesn't care how the planet spins below it, all it worries about is having enough forward momentum to equal the force of gravity from whatever body it is orbiting. This is the whole reason why its advantageous to launch your rockets to the east, because you get to inherit the speed of the earths rotation for free as you leave the atmosphere. You CAN launch your rocket west if you want but you will need more Delta-V to reach orbit.

Edited February 5, 2020 by Deano87

[Hummingbird]

For energy and G calculation , it must use TAS. Mach number is from TAS, not IAS.

 

Yup, accurate calculation of G forces & rate is only possible via TAS. Hence why performance manuals come with speed conversion charts to convert IAS and/or CAS into TAS, these are different for every aircraft.

 

F-14, F-15, F-16 etc. EM charts are all in TAS, mostly True Mach Number.

Edited February 5, 2020 by Hummingbird

[David OC]

Because the air its flying through is also traveling at 1000mph with the earth. So its lifting potential is ONLY the relative motion between it at the aircraft. Even as the aircraft is flying vertically upwards (compared to the ground below it) its still actually traveling at 1000mph sideways with the rotation of the earth. If it DID suddenly inherit the energy of the earths rotation you would have got free energy, because it would be climbing vertically at 1000mph, but ALSO traveling sideways at 1000mph. This leads me to the question, IF pulling to the vertical would add energy from downwind (it doesn't but lets imagine), then why not turning 90 degrees left or right (crosswind), What would the difference be? Surely that would also add energy as well, the same physics are happening, only 90 degrees different. Think about why that doesn't happen when turning crosswind, and you get your answer as to why it doesn't happen when pulling to the vertical.

 

Well an orbital velocity is not really related to ground speed either. Say you orbit your space craft around the equator but in the opposite direction to the earths spin, your GS would be +2000 mph faster then it would be orbiting with the earths spin, but your orbital velocity compared to the solar system would be the same. Once in space the ship doesn't care how the planet spins below it, all it worries about is having enough forward momentum to equal the force of gravity from whatever body it is orbiting. This is the whole reason why its advantageous to launch your rockets to the east, because you get to inherit the speed of the earths rotation for free. You CAN launch your rocket west if you want but you will need more Delta-V to reach orbit.

 

Soon you'll be allowing for earth's 67,000 mph speed around the sun.:)

[Deano87]

Soon you'll be allowing for earth's 67,000 mph speed around the sun.:)

 

Well indeed. Our solar system is doing about 500.000 mph in some direction as well. :lol:

 

My point was obviously that none of these inherited motion effects are seen in reality, thankfully.

Edited February 5, 2020 by Deano87

[Fri13]

Wind effects the ground track of the aircraft. But it does not effect how the aircraft flies or its performance.

 

You just explained that aircrafts ain't aircrafts, but groundcrafts... Maybe we should as well call spacecrafts as orbitcrafts....

 

The air speed is indicated because it doesn't matter what happens on ground. Same way as all aeronautical calculations are all about speed of wind in relative to the aircraft attitude.

Be there a zero wind, high wind, thin air etc... It is all about air and aircraft attitude to it.

 

There is no ground, there is inertial movement that can be calculated and that as well is all about air speed and relative attitude for the aircraft and its shape.

 

 

We can place an aircraft to wind tunnel, and consider that there is no ground, there is nothing else than a gravity that is pulling aircraft down, and to fly you need lift.

And what you need to do to generate lift? Just a high air speed from any direction as long it is steady and the aircraft will counter the gravity?

 

Since when we did receive a anti-gravitation generators so that our aircrafts can counter the gravity regardless the air flow direction or strength?

 

In aeronautical, ground speed is just one element of many in flight. Gravity is one of the core elements. If you can't overcome gravity, you are either in weightless space or you will be moving toward gravitational force that is pulling you to it. And why you don't want that?

 

Air and its speed affects directly to the aircraft. It doesn't matter is the aircraft stationary or flying, and it doesn't matter is it air speed as wind, or is it aircraft speed by propulsion, it is all about the direction, speed and the relative effects by the aircraft shape.

 

Otherwise we would all be flying spheres, as air doesn't matter and only gravitation would be required to be countered.

[JUICE-AWG]

Honestly, I would report bugs once and with acknowledgement...wait until the Changelog comes out and verify fixes. Remember, the Viper is still in development.