Trying to simulate instrument errors in a VSI

Questions about deployment and use of Air Manager Instruments

Moderators: russ, Ralph

Message
Author
JackZ
Posts: 2267
Joined: Mon Feb 22, 2016 1:02 pm

Re: Trying to simulate instrument errors in a VSI

#11 Post by JackZ »

Good proof of concept, but I am afraid that’s a bit of a hair pull.
Most if not all of the modern aircrafts are equipped with IVSI (instantaneous vertical speed indicator), built to counteract the effect you’re trying to implement by using counterweights and small pistons.
https://www.mcico.com/resource-center/a ... t-lag-time

The reaction time lag of a standard VSI is for vintage aircrafts with old VSIs. It can be up to 6-9 seconds
My YouTube Chanel on the A320 (Real SOPs by an Airline Pilot IRL):
https://www.youtube.com/playlist?list=P ... 0Q6SBASRqJ

SimPassion
Posts: 5346
Joined: Thu Jul 27, 2017 12:22 am

Re: Trying to simulate instrument errors in a VSI

#12 Post by SimPassion »

Good point Jacques 👍, exactly what I need :

image.png

JackZ
Posts: 2267
Joined: Mon Feb 22, 2016 1:02 pm

Re: Trying to simulate instrument errors in a VSI

#13 Post by JackZ »

Yeah. IVSI Have INSTANTANEOUS written on the face of the Gauge somewhere
My YouTube Chanel on the A320 (Real SOPs by an Airline Pilot IRL):
https://www.youtube.com/playlist?list=P ... 0Q6SBASRqJ

SimPassion
Posts: 5346
Joined: Thu Jul 27, 2017 12:22 am

Re: Trying to simulate instrument errors in a VSI

#14 Post by SimPassion »

JackZ wrote: Wed Oct 11, 2023 1:20 pm Yeah. IVSI Have INSTANTANEOUS written on the face of the Gauge somewhere
Yes, as in the picture shown above 👍

frumpy
Posts: 361
Joined: Sat Jan 30, 2016 12:01 pm

Re: Trying to simulate instrument errors in a VSI

#15 Post by frumpy »

I have only flown standard VSIs, but it was 20 years ago, is that vintage? :) I assume that in most steamgauge 172s and modern ULs you can find at the airfields have non-IVSIs. I used to work at an airfield and looked at the gauges, afaik IVSIs are more for IFR equipped aircraft.

I am easily bothered by all too perfect displays of aircraft systems in a flightsim. Like engine 1 values are identical with engine 2 values and they change exactly at the same instant moment and of course always have perfect sensors with a 1°C resolution and so on, you name it. Elite flightsim did better 25 years ago (btw. you can setup each plane having a standard or IVSI). I feel with AM and it's posibilities to alter values a bit we can greatly increase immersion, like Jacques did with the vibration needle effects.

For IVSIs, this can be a swinging movement of the needle when flying through rough air since the counterweight starts moving. But I don't think this is easily feasible in X-Plane, yet it does not make too much sense without a motion platform.

JackZ
Posts: 2267
Joined: Mon Feb 22, 2016 1:02 pm

Re: Trying to simulate instrument errors in a VSI

#16 Post by JackZ »

I think even 20 years ago most of the VSI were already in fact IVSI. I have not flown any GA aircraft for a while, but I don’t recall having encountered VS lag delays such as 6 to 9 seconds which seems A LOT.
In my Airbus we don’t have this problem anyways as data comes from the Air data reference computers (ADR) and is therefore compensated.

As per to “to clean to be true” I do agree with you, as once again even in the Airbus it is common to see differences on altitude displays between captain’s and F/O PFD’s of like 10 to 20 feet.
My YouTube Chanel on the A320 (Real SOPs by an Airline Pilot IRL):
https://www.youtube.com/playlist?list=P ... 0Q6SBASRqJ

User avatar
jph
Posts: 2857
Joined: Fri Apr 10, 2020 12:50 pm
Location: Somewhere over the rainbow..

Re: Trying to simulate instrument errors in a VSI

#17 Post by jph »

Interesting project and great work and input.
Nice.
Joe
Joe. CISSP, MSc.

frumpy
Posts: 361
Joined: Sat Jan 30, 2016 12:01 pm

Re: Trying to simulate instrument errors in a VSI

#18 Post by frumpy »

JackZ wrote: Fri Oct 13, 2023 4:03 pm I think even 20 years ago most of the VSI were already in fact IVSI. I have not flown any GA aircraft for a while, but I don’t recall having encountered VS lag delays such as 6 to 9 seconds which seems A LOT.
Here its quite a few seconds:
https://youtu.be/YIOGik5klB4?feature=shared&t=115

Here is also a very slow VSI, left of the standby horizon:
https://youtu.be/nHaQ-8ta9EY?feature=shared&t=306

frumpy
Posts: 361
Joined: Sat Jan 30, 2016 12:01 pm

Re: Trying to simulate instrument errors in a VSI

#19 Post by frumpy »

Next version is up.

Changes:
- speed limitation of the pointer is removed for now, as it did not feel right and the code looked nasty
- random offset of +-50 ft/min added; afaik this is the normal range for instrument error
- ground effect added; while the plane is in ground effect, the static pressure rises. This causes a negative reading on takeoff and landing; for real life check this: https://youtu.be/RQCBihrk0EY?feature=shared&t=660
- some random changes due to turbulence; I did not find any dataref for up/downdrafts, so I used fluctuations of the wind and brought the mean to 0; check this: https://youtu.be/r83l8sU12Ak
- strength of ground effect and turbulence can be tweaked to your liking with the initial variable definitions

Thats a demo of the offset and ground effect:
https://youtu.be/3cz57kwi4dI



Post Reply