[NO BUG] Speedometer Bug

[VO101_MMaister]

Hi,

 

I was in an online game, low on fuel and on my way back to base when a strange speedometer behavior came up.

 

The instrument started to act reversed, so when I gained speed it was indicating sinking speed when I dropped speed it was showing increasing. Very strange. My plane was undamaged.

I was afraid that it wont be shown on a track, so I reached for my phone to take a video. Here it is:

 

]

[Anatoli-Kagari9]

Hi,

 

I was in an online game, low on fuel and on my way back to base when a strange speedometer behavior came up.

 

The instrument started to act reversed, so when I gained speed it was indicating sinking speed when I dropped speed it was showing increasing. Very strange. My plane was undamaged.

I was afraid that it wont be shown on a track, so I reached for my phone to take a video. Here it is:

 

]

 

Probably damage to your pitot dynamic port ?

[MAD-MM]

Must be not a bug, can be icing on the pitot tube.

[VO101_MMaister]

Probably damage to your pitot dynamic port ?

 

Can be!

I wasn`t hit and I wasn`t in any extraordinary flight situation when it came up (3000m, about 600km/h), that is why I thought that it might be a bug.

[Nedum]

Must be not a bug, can be icing on the pitot tube.

 

 

How so?

If the tube is iced how can it show changes in a direct reaction on the true speed change (gain height or lose height)? Shouldn’t it show constant less speed but in such a way that if the plane gains more speed it should show more speed but less as with as ice-free tube? Even the tube is iced or has a defect it shouldn't react like it did in the vid.

[VO101_MMaister]

Well, icing rarely happens at clear blue sky. But it makes sense regarding the shympthoms.

 

If the dinamic intake of the pitot freezes then the speed indication can reverse. The trapped pressure in the dynamic intake will be relatively lower compared to the static when you dive so the speedometer will function reversed. The counterside applies when you climb.

 

Anyway, I hope that the developers can have a look at this one and confirm that it is a coded feature of an instrument failure.

[NeilWillis]

I don't have a speedometer in mine, I have an air speed indicator. Perhaps that's the problem? AFAIK, speedometers generally work by having a cable drive from the gearbox, or a wheel.

 

Aircraft don't generally get fitted with them as they're not touching the ground enough to make speedometers a very useful instrument.

 

Pitot freezing definitely affects air speed indicators though, and I believe they can freeze in almost any climatic conditions. All you need is water and sub zero conditions which can be present even on the sunniest of days.

[Anatoli-Kagari9]

A blocked pitot-static problem will only affect airspeed indicators.

 

A blocked pitot tube will cause the airspeed indicator to register an increase in airspeed when the aircraft climbs, even though actual airspeed is constant.

 

This is caused by the pressure in the pitot system remaining constant when the atmospheric pressure (and static pressure) are decreasing. In reverse, the airspeed indicator will show a decrease in airspeed when the aircraft descends.

 

I'm glad to find DCS correctly models this. Will search for the remaining error combinations of dynamic / static / both ports, all modeled correctly only on a few sims ELITE being the only one for GA that I know models it correctly.

 

See "https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2007.pdf"

 

under "Blocked Pitot System"

Edited February 7, 2016 by jcomm

[VO101_MMaister]

I don't have a speedometer in mine, I have an air speed indicator. Perhaps that's the problem? AFAIK, speedometers generally work by having a cable drive from the gearbox, or a wheel.

 

Aircraft don't generally get fitted with them as they're not touching the ground enough to make speedometers a very useful instrument.

 

Pitot freezing definitely affects air speed indicators though, and I believe they can freeze in almost any climatic conditions. All you need is water and sub zero conditions which can be present even on the sunniest of days.

 

Well, as a non native english speaker it is always a pleasure to be educated by knowledgeable natives about the right expressions ;)

[saburo_cz]

Same trouble for DCS Fw 190D, my pitot tube froze several times on two servers with winter map. It happened when i climbed above 3km and spent there some time. After i descended to low altitude this trouble diappeared within few minutes.

I have always switch on pitot-tube heating, question is : does it (pitot heating) simulated corectly or bug is here?

[VO101_MMaister]

Well I keep being amazed by the details of DCS...

[Anatoli-Kagari9]

Well I keep being amazed by the details of DCS...

 

Me too - together with Aerowinx PSX, they're my study sims :-)

Edited January 29, 2016 by jcomm

[NeilWillis]

Well, as a non native english speaker it is always a pleasure to be educated by knowledgeable natives about the right expressions ;)

 

Not an educational posting, but using the correct terminology will certainly help you find a solution if you choose to do some further research. I hope you didn't think I was being offensive. There isn't really a way of saying anything here without someone taking it badly, but sometimes a nudge in the right direction will help, and saying nothing might mean you can't find exactly what you need to find.

 

The first place to look for anything is the manual, and I am certain you'll never find any mention of speedometers in them.

[VO101_MMaister]

Not an educational posting, but using the correct terminology will certainly help you find a solution if you choose to do some further research. I hope you didn't think I was being offensive. There isn't really a way of saying anything here without someone taking it badly, but sometimes a nudge in the right direction will help, and saying nothing might mean you can't find exactly what you need to find.

 

The first place to look for anything is the manual, and I am certain you'll never find any mention of speedometers in them.

 

No bad feelings NeilWillis, you were right about the terminology. :thumbup:

[NeilWillis]

I'm glad you see it the way it was intended. Thanks V0101 MMaister.