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Vehicle and Terrain threads Discussions about environment and vehicles in CoD

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  #1  
Old 12-12-2011, 05:27 PM
bolox bolox is offline
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Default The British ASI

one thing that has caught my attention since release is the needle behaviour of the British ASI's:- there is a marked drop in indicated speed as G is pulled, something that definitely doesn't appear with German instruments.
I can think of no reason for a difference in the behaviour, both being similar systems

While we're talking asi's- what is going on with the hurri and blen asi?
i've never seen a British asi(of the period) with dual needles, all having a single needle as depicted in the spit

spit/huuri asi


320 mph asi blen (and many others)
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  #2  
Old 12-13-2011, 02:58 AM
IvanK IvanK is offline
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This bug of the UK ASI needles responding instantly to backstick has been brought up directly with the devs.
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  #3  
Old 04-04-2012, 05:43 PM
Ataros Ataros is offline
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The devs response at il2bugtracker.com
Quote:
Working as intended, historically accurate. (updated by Ilya "Luthier" Shevchenko and Roman "Mad Dragon" Deniskin)
http://www.il2bugtracker.com/issues/2

Interesting details in modelling.
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  #4  
Old 04-04-2012, 07:31 PM
fireship4 fireship4 is offline
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Finally a bug tracker! It has been needed and easy to get (correct me if I'm wrong) since the start.
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  #5  
Old 04-05-2012, 03:16 AM
IvanK IvanK is offline
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Quote:
Originally Posted by Ataros View Post
The devs response at il2bugtracker.com
http://www.il2bugtracker.com/issues/2

Interesting details in modelling.
"Working as intended, historically accurate. (updated by Ilya "Luthier" Shevchenko and Roman "Mad Dragon" Deniskin) "

I cant believe that as accurate. I am yet to see any ASI behave in this manner including on some relatively ancient types. Given we are talking about basic Pitot static devices in both RAF and Luftwaffe types why should the only the RAF ASI exhibit this behaviour ?

This DVD



http://www.amazon.co.uk/Supermarine-.../dp/B000AOX79M

Contains some exceptional in cockpit over the shoulder imagery of a MKI being test flown. This includes a a full low level aerobatic routine in which the ASI can be clearly seen.
There are NO wild reductions in IAS as G is applied. You do see normal IAS reduction as the speed varies throughout the manoeuvres but you don't see ASI needle reductions/fluctuations responding to G/backstick increases.

Here is a screen grab to illustrate the view presented in the DVD test flight the ASI is clearly visible throughout:



And another DVD with Cockpit Cam showing a display routine in a Hurricane I

http://www.amazon.co.uk/ITVV-Hurrica.../dp/B0036U2VGW
Its cockpit viewpoint shown in this screen grab:

Again NO large ASI swings under G/Backstick. Some minor oscillations in the order of +-5MPH max are evident.

-----------------------------------------------------------------------------

In the case of large Yaw inputs (particularly at low IAS) then some small oscillation could be expected since the Pitot head on the RAF types is located on the outboard section of the wing. (Port wing in the Spits case) therfore the pitot head would experience local airspeed changes with yawing. e.g. If the YAW input results in the pitot head "advancing" into the airstream (On the Spit with the Pitot head on the outer port wing yawing RIGHT) then you could expect a momentary minor increase in IAS. Once the YAW stabilises the ASI would be constant. The opposite being the case if the yawing moment results in the pitot head retreating in the airstream (in the case of the Spit Yawing LEFT). This is one of the reasons why with aircraft with Pitot heads on the outboard wings that you see differing stabilsed IAS values in a spins to Left and Right.

There is no rational reason imo why this should occur in the pitch axis.

Last edited by IvanK; 04-05-2012 at 06:29 AM.
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  #6  
Old 04-05-2012, 06:50 AM
Ataros Ataros is offline
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S!
I am not an expert but maybe a pitot tube has different design or located differently compared to axis ones? What do experts say on WWII historical forums? We have some here in Russia but I am not a member.

Are you sure the videos show authentic instruments?

If yes, could you post the evidence into bugtracker http://www.il2bugtracker.com/issues/2
and ask mods to change the issue status to "new" or add a new status like "updated". We can discuss it here http://www.il2bugtracker.com/boards/1/topics/15?r=17
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  #7  
Old 04-05-2012, 07:20 AM
IvanK IvanK is offline
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Posted on Bug tracker forum asking for the bug to be reactivated,.... and with the devs directly again !

Shouldn't be closed/Rejected subject on Bug tracker imo it should still be open.

Yes these Aircraft are faithful restorations using original components.

The 109 Pitot probe is in a similar location to the Spitfire under the outboard portion of the port wing, and yet it does not exhibit the same (bugged imo) behaviour as the RAF types.

Last edited by IvanK; 04-05-2012 at 08:07 AM.
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  #8  
Old 04-05-2012, 08:43 AM
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Osprey Osprey is offline
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A bug tracker is fantastic as long as there is control - perhaps a few people here who have permission to raise and comment on defects. The last thing we want are biased statpadders to spoil the game in their favour.

Last edited by Osprey; 04-05-2012 at 08:50 AM.
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  #9  
Old 04-05-2012, 10:15 AM
bolox bolox is offline
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IvanK, thank you very much for your input, agrees totally with my limited experience of flying relevant types (Chipmunk and Harvard).

The last thing i wish to do is cause a 'war' over this (or any other issue) and further overload Ilya and the team, however at the very least it is inconsistent with the behaviour of other nations asi's.

anyway for those who want to know a little more how pitot systems work and their errors maybe of interest
http://www.nar-associates.com/techni...ide_screen.pdf
or for the more technical
http://ntrs.nasa.gov/archive/nasa/ca...1993092348.pdf
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  #10  
Old 04-05-2012, 12:30 PM
Ataros Ataros is offline
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Reopened the issue.
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