PSXseecon version 3.23 released

[Hardy Heinlin]

One method to calculate IAS with True Altitude, QNH, TAS, OAT:

1. Compute Pressure Altitude using True Altitude, QNH.

2. Compute Mach using TAS, OAT.

3. Compute IAS using Pressure Altitude, Mach.


Anyway, I'll add that IAS Qi. I think I'll set its rate to 10 Hz.


Regards,

|-|ardy

[kiek]

Simon
Oh. You are right. My first thought is when QNH change, the difference between IAS and TAS will also change. But it seems to more relate with altitude then QNH

No Simon is not right... You need the pressure altitude, which is QNH dependent.

[b744erf]

Sorry for my poor aviation knowledge 😂. Right, the pressure altitude needs QNH.

And, just one more question. Since I have spent a long time to find the way to calculate the IAS, I am still curiosity to know the Q code for current position QNH and OAT. I can only find them from pre-setting airport weather and the planet weather, which may not be the aircraft surrounding wx.

Of course, I will definitely wait for the new Q code for IAS

Regards
Jack

[Hardy Heinlin]

You can get the pressure altitude directly from Qs562:

https://aerowinx.com/board/index.php/topic,2514.msg73175.html#msg73175


Regards,

|-|ardy

[simonijs]

So, just for my understanding: using Q-variables and PSXseecon - for the purpose of calculating IAS - Pressure Altitude and QNH are required? Because when writing my post the other day, I was wondering: how would you get QNH at 54N040W?

I am asking since my formulas all use pressure and density at ISA MSL, plus pressure and density at altitude (amongst others). But not QNH. Results were always within ± 0,1% of PSX Embry Riddle FDR data.

And just for the record: I was asking a question, and remarked that I was not aware of a formula that uses QNH. After two further posts this then became "No Simon is not right". Using Dutch language: beetje kort door de bocht.

Regards,
Simon

[Hardy Heinlin]

... for the purpose of calculating IAS - Pressure Altitude and QNH are required?

No, if you already have the Pressure Altitude you need no QNH. You didn't get that wrong :-)

The sim designers initially just see the True Altitude, not the Pressure Altitude. In order to compute the Pressure Altitude from the True Altitude, they need to know the QNH at the current position.

From a pilot's point of view, however, you just set STD on the altimeter and you see the Pressure Altitude directly on the instrument. But from the sim designers's perspective, you initially get the geometric (true) altitude relative to the simulated 3D world sea level. At that point, any air data is irelevant; there's just geometry.

The pilot wants to derive the true data from the instrument data.
The sim designer wants to derive the instrument data from the true data.


Regards,

|-|ardy

[kiek]

And just for the record: I was asking a question, and remarked that I was not aware of a formula that uses QNH. After two further posts this then became "No Simon is not right". Using Dutch language: beetje kort door de bocht.

Hi Simon,
Since you seem to know Dutch, I"ll switch to Dutch which is easier for me:

Uit jouw vraag maakte ik op dat je niet kon geloven dat je QNH nodig had. Als je al een pressure altitude hebt dan natuurlijk niet, maar als je de pressure altitude moet berekenen dan wel. Zie ook
Hardy's post hiervoor. Ik doe zelf niets anders in mijn PSXT programma's.

Mijn antwoord kon inderdaad wat bot opgevat worden, dat spijt me.

Groeten,
Nico

[simonijs]

Hi Hardy,

Thank you for explaining; now I understand why QNH is required for sim designers!


Goedemorgen Nico,

Yes, very Dutch indeed. I live in Amsterdam (with a son living in Delft), but have been away from home, computer and books since the end of March. Thank you for your kind reply as well.

Regards,
Simon

[b744erf]

You can get the pressure altitude directly from Qs562:

https://aerowinx.com/board/index.php/topic,2514.msg73175.html#msg73175


Regards,

|-|ardy

Thank you Hardy.

[Hardy Heinlin]

PSX version 10.175 is up with a new Qi for the standby IAS:

https://aerowinx.com/board/index.php/topic,2514.msg79856.html#msg79856


I discarded the idea of using the existing Qi37 ("StbyIasError"). Unlike I thought yesterday, this is actually an effective implementation. It's default value is 1000 which represents the factor 100%, e.g. 900 would stand for 90% and when an add-on injects such a factor into PSX, the standby instrument in PSX will show an IAS value that is factored accordingly. The value is stored in situ files. All situ files so far contain the normal value 1000. If an add-on injects a different value, it can only be reset by another injection or by editing the related situ file. The malfunction reset button in PSX will not reset this particular error. -- Anyway, that's why I keep that old Qi37. It has to be compatible with the old situ files.


Regards,

|-|ardy

[kiek]

I will add the new Qi to PSXseecon when I am back from vacation (week of June 10th).

[b744erf]

Thank you Hardy! Thank you Nico! Thanks for the super quick update! Appreciate your help. Can't imagine that one day I could be the one who ask for an update for PSX :p

And one more question. Since I am also building my standby attitude indicator. I am going to use Qs121, which includes pitchRad and BankRad (4880 and 4881 in PSXseecon). Are there any Q variables (Or PSXseecon variables) show the PSX standby gyro data? So that I could also simulate the caging action. I am not asking for the new variables. But just want to confirm if I am using the correct variables. whats more I would like to ask how PitchRad and BankRad work. It seems that the pitch move every 1 degree, both data move about 1750. I can hardly figure out the precise number because it moves too fast. What is "Rad" short for?

Regards
Jack

[Hardy Heinlin]

Rad means radian. It's another unit for the angle value. Programming languages usually work with radians rather than degrees.

360 degrees are equal to 2*pi radians (circa 6.283 radians).

In the PSX network, pitch and bank angles are provided as the rounded result of radians * 1000. E.g. -3142 corresponds to -180 degrees.

Negative pitch means nose down.
Negative bank means bank left.

You may use Qs321 for some standby attitude effects:

Qs321="MechAtt"; Mode=ECON; Min=7; Max=20;

This string always starts with "1;" -- you can ignore that. The remaining three variables are:

pitchErrorAdd * 1000
bankErrorAdd * 1000
gyroRpm * 1000

The errors are angle values that need to be added to the true attitude angles. Normally, the error values are "0".

I guess the caging knob in your hardware works mechanically and holds the attitude at the neutral position? If so, you need not care about the caging simulation in PSX.


Regards,

|-|ardy

[b744erf]

Oh!!! Thank you for the detailed explanation. I just checked the PSXseecon variables. For now it dose not include Qs321 data. So I could only use QS121. Hope if possible, Nico could add it as well. 🫡.

About the caging, I would say it is impossible to work like a OEM one. My standby gyro is actually working with two Servo motor, like the standby IAS indicator. I will add a micro switch to detect the pulling action for caging. But I need a data from PSX to simulate the gyro error or stay at a non normal position which need to be caging. For now I am going to write a script that when the aircraft is not power, the indicator will be at a nonnormal position. It will be normal when pulling the caging, but go back to the non normal position again when releasing. But It don't need the caging if the aircraft is powered up. I know it is not how the real world works. But it is the only thing I could do for fun. Haha

I think I can finish replacement work for the gyro parts. I will upload a video for that as well. Thank you Hardy and Nico, and the superb PSX and PSXseecon.

Regards
Jack

[kiek]

Hello Jack,

I will add Qs321 too, no problem.

Btw, you are the first to ask for it in 10 years. You must be  building a superb flight deck!?

It would be nice to put a link to a video of your cockpit at my site  to illustrate the power of PSX + PSXseecon + SIOC.

Kind regards,
Nico

[Jeroen Hoppenbrouwers]

Question concerning mechanical (gyro) attitude indicators.

I know they topple when either the gyro spins too slowly or the attitude reaches the mechanical limit (which obviously is not there on a military fighter or aerobatic aircraft).

However -- if the airplane is at physical rest on the ground and you pull the power (electrical, pneumatical) off the gyro motor, does it always topple or does it gradually become more unstable but may remain quite upright?

Hoppie

[b744erf]

Hello Jack,

I will add Qs321 too, no problem.

Btw, you are the first to ask for it in 10 years. You must be  building a superb flight deck!?

It would be nice to put a link to a video of your cockpit at my site  to illustrate the power of PSX + PSXseecon + SIOC.

Kind regards,
Nico

Nico.

It would be my great honor to have my simulator appear on your website! This is the Facebook account I specially set up for my simulator, MySim Seven Four. Unfortunately, I haven't updated it often. However, there are some recent photos of it inside.

https://www.facebook.com/profile.php?id=100090742840185&mibextid=LQQJ4d

I am currently on a business trip. By the middle of next week, I will be at the simulator, and I will take more photos then.

Thank you Nico.

By the way, I am now using the PSXseecon CDU for all three of my CDU displays, which wonderfully saves a lot of power on my computer. I would like to try controlling the brightness of the CDU by interfacing a potentiometer with an OpenCockpit board. Does PSXseecon include this function?

Regards
Jack

[kiek]

I am not sure that the brightness's of the CDU's is in Hardy's Q variables... It would surprise me.

[Hardy Heinlin]

The CDU brightness potentiometer angles are here:

Qh404="BrtCduL"; Mode=ECON; Min=0; Max=4713;
Qh405="BrtCduC"; Mode=ECON; Min=0; Max=4713;
Qh406="BrtCduR"; Mode=ECON; Min=0; Max=4713;

4713 (radians * 1000) corresponds to 270°.

The brightness pushbuttons on the LCD CDU also use these Qh variables.


Regards,

|-|ardy

[kiek]

The CDU brightness potentiometer angles are here:

Qh404="BrtCduL"; Mode=ECON; Min=0; Max=4713;
Qh405="BrtCduC"; Mode=ECON; Min=0; Max=4713;
Qh406="BrtCduR"; Mode=ECON; Min=0; Max=4713;

4713 (radians * 1000) corresponds to 270°.

Ah I see. Thx Hardy.

@Jack, Yes they are in PSXseecon too.