[INVESTIGATING] ASI indication bug

ASI shows instantaneous drops with application of AOA/G. This can be in the order of 50+mph. Its not energy bleed. As soon as you reduce the AOA the ASI needle jumps back to its original value. You can drive the ASI needle all over the place by just relatively minor applications of AOA/G. There is ample Spitfire cockpit video around that clearly shows this behavior is wrong.

 

It was porked in another Sim as well .... same coder ?

I noticed this too. Of course, at higher AoA the ASI should show less, but right now it's jumping all over the place, very unrealistic.

I haven't flown the Spitfire for more than a year. Tried it today and honestly I am shocked this problem is still not solved. This is not something of little importance. Really nobody is bothered by this? Developers included?

ASI shows instantaneous drops with application of AOA/G. This can be in the order of 50+mph. Its not energy bleed. As soon as you reduce the AOA the ASI needle jumps back to its original value. You can drive the ASI needle all over the place by just relatively minor applications of AOA/G. There is ample Spitfire cockpit video around that clearly shows this behavior is wrong.

 

It was porked in another Sim as well .... same coder ?

 

So, you pull G's and the speed won't bleed? Only on the ASI? hmm..

So, you pull G's and the speed won't bleed? Only on the ASI? hmm..

 

 

This depends on if you have the flight data showing. It would be easy to test in DCS... I might take a look at this sometime this week, if I find some free time!

Hmmm, I was only aware that reading errors due to sideslip were modeled, which is actually a nice feature.

 

Never noticed this other discrepancies ? Will check when possible and report back ...

ASI shows instantaneous drops with application of AOA/G. This can be in the order of 50+mph. Its not energy bleed. As soon as you reduce the AOA the ASI needle jumps back to its original value. You can drive the ASI needle all over the place by just relatively minor applications of AOA/G. There is ample Spitfire cockpit video around that clearly shows this behavior is wrong.

 

It was porked in another Sim as well .... same coder ?

I understand you mean airspeed indicator. Well at high angles of attack it can definitely show false readings by pitot tube errors due to aerodynamic effects. I don't really know if that's any bug or just how this instrument in particular was. Many more British instruments in the Spitfire cockpit are not specially reliable so it won't be any news this one also is.

 

 

S!

It is not a problem!

Most of us cannot see the needle on the ASI anyway. :D

spitfire in still in beta, it is most likely that bugs fixes are in progres

You have the wrong information, the module Spitfire release from 02-03-2017.

 

- Access Release v1.5.5.60314

- Release Support v2.0.5.1648

You have the wrong information, the module Spitfire release from 02-03-2017.

 

- Access Release v1.5.5.60314

- Release Support v2.0.5.1648

 

you are right wow i though that spit got released not far ago, time for me passing so quick :P

This is a bug? The ASI indication drop (and increase) with AoA/G application was so obvious I figured it must be real, otherwise it would've been fixed.

It's not just the ASI. The altimeter changes simultaneously, it can instantly gain or lose 1000 feet+. I'm not sure if the VSI acts correctly (or in concert).

 

Something that could account for this. A common reference air pressure intake.

 

A certain glider I know have a common reference static air pressure intake in the tail supplying the ASI, Altimeter and two VSIs (four instruments). When flying slow and turning as tight as possible, this static pressure intake gets in the shadow of the wing and becomes turbulent. Long story shorter, in this specific situation, all four static air pressure dependent instruments goes apeshit. They (ASI, VSIs & Altimeter) stutter synchronously with maybe 10 Hz frequency and a small amplitude.

 

Not exactly how the Spitfire instruments act, yet similar in that multiple instruments are affected synchronously. Something like this is plausible for affecting all air pressure dependent instruments (altimeter, ASI and maybe also Spitfire VSI).

 

An hypothesis, assuming the best efforts of DCS programmers. They have modeled the instruments to the best of their ability (including a common air pressure intake), and this is the result they get. The fact both ASI and altimeter acts synchronously indicates that the modeling equations have them connected.

 

When flying fast (even a glider that Vmax at a relatively slow 170 mph) you don't jerk the stick. The G forces are felt instantly. Breathe on the stick (pitch wise) and you'll feel it in your spine.

 

In an armchair with a joystick on your desktop otoh, you feel nothing and and you jerk the stick in a way you never would in real life and this causes air intake pressure differences (admittedly this assumes air pressures intakes are modeled to a possibly ridiculous detail).

 

It would be convenient if the Spitfire had a G meter. The P51 has a G meter and as an experiment one could try never moving the stick more than resulting 0.5 - 1.5 G and compare how one moves the stick not watching the G meter. Note the difference between deliberately applying high G force and just flying normally. 2G, for example, is very noticeable in real life and 'normally' turning, climbing & diving you never apply this, unless you feel like it. I think (not having stared at the glider G meter) normally it's even less than +-0.5G.

 

I struggle with this obvious bug, not being fixed for so long, so maybe it isn't strictly a bug. Or not a bug that can be fixed without compromises.

~

 

 

Edited sentences and wording for clarity

"static", I just remembered the terminology for this glider intake was "static"

Edited June 25, 2019 by -0303-

Considering how a ASI works, it seems like the airflow into the pitot tube get's disturbed at high AoA. I would be amazed if ED modelled this.

I would be amazed if ED modelled this.

I remember something about that was modelled as instrument error due to high AoA, but as descriptions are so unclear I don't know if the reading error OP means is that or there really is a real bug now.

 

 

S!