Dynamic stall discussion

[Insuber]

Originally Posted by ACE-OF-ACES

No don't be so hard onyourself! I realise you were un-able to explain the difference which is why I ask you for the link in the russian forum


Ah good so you agree with me and the link I posted a few pages back, i.e.

Advanced Topics in Aerodynamics

Where it defines a dynamics stall as..




What your forgeting is there is a chance that CoD does simulates stick inputs the same way IL-2 did.. Where the stick input is not a position offset as much as a force input.. That is to say just because you move the still all the way 'back' does not mean your elevator moved all the way 'up'.. What is actully going on is when you move your stick all the way ack, your have appled the max force input.. Thus if your max force input is limited to 20lb and due to the airspeed it would require 60lb to fully deflect the elevator.. Well you can see your not going to fully deflect the elevator


And your welcome to it! S!

You are welcome my friend! I'm glad that you evolved from your yesterday's position of "what's a dynamic stall", and then "no need to waste time to model the dynamic stall", IIRC ... Only fools never change their mind, and you're not one of them luckily.
Regarding the topic, I've found the issue of , I've asked the question to B6 and I've got my answer. And I'm happy that someone learned some lil' bits of aerodynamics in the process.

[ACE-OF-ACES]

Originally Posted by TomcatViP

Dyn Stall =

A stall that has its root in a dynamic phenomena. A stall is essentially linear : the AOA increase (or the speed decrease at a given aoa). In the dyn stall the flow ard the wing is disturbed briefly inducing non linear effect

The source can be mechanical (aileron reversing), aerodynamic (temp vortex) or thermal (critical temp inducing critical external pressure change - eg turbulences)

An example will be the rotor blade turning around it's axis. The blade AoA hve to be raised when the blade travel backward in order to compensate for the loss of speed and equilibrate the lift generated by the rotor.

At certain speed the AoA variation can be critical to the airflow generating vortex on top of the blade that prevent the normal airflow circulation. The flow is separated at a higher than normal speed and the blade is stalled (generating a high amount of drag).

Agreed in that your definition agrees with the links I have posted thus far..

S!

[ACE-OF-ACES]

Originally Posted by Insuber

You are welcome my friend!

Ditto!

Originally Posted by Insuber

I'm glad that you evolved from your yesterday's position of "what's a dynamic stall"

Ah, now I see why you were so confused!! I wasn't asking what a dynamic stall is as much as I was asking what 'they' (you being one of the they) were saying what a dynamic stall is.. Does that help you?

Originally Posted by Insuber

, and then "no need to waste time to model the dynamic stall",

That still depends on how brief is brief.. As I noted, if CoD is not currently simulating accelerated stalls, than yes that should be added.. But the difference between an accelerated stall and a dynamic stall could be so small as to go un-noticed, and thus not needed to simulate. For example, if your telling me that in a dive in CoD, if I pull the stick hard & fast and the plane never stalls.. Than CoD is not even simulating an accelerated stall and it should.. But assuming it does stall.. Than what your talking about adding is the 'brief' increase in lift just prior to the stall to the accelerated stall code to simulate the dynamic stall.. My point an others is that 'brief' spike in lift may go un-noticed if it only lasts for a Millie second.. Does that help you?

Originally Posted by Insuber

IIRC ... Only fools never change their mind, and you're not one of them luckily.

This is true! I am very open minded.. So open minded that I ask people to explain what it is they are referring to as oposed to assuming what it is they are referring too.. Problem is there are some here he don't really know what they are talking about and thus can not explain what it is they are referring to without showing everyone they really don't know what they are talking about

Originally Posted by Insuber

Regarding the topic, I've found the issue of , I've asked the question to B6 and I've got my answer. And I'm happy that someone learned some lil' bits of aerodynamics in the process.

And only time will tell.. Guess we will have to wait for the CoD update/patch to see who really learned anything here today! S!

[Insuber]

ACE, I think that being in a forum you must be more straightforward and direct, rhetoric questions and elliptic thesis get easily misinterpreted. I thought indeed that you ignored a simple concept such as the now famous DS, and denying the need to add it to the FM. Moreover I thought erroneously that you were trolling around trying to hijack the discussion and confuse B6. I'm glad to discover that you are the finest and deepest expert of aerodynamics of this forum. S!

Cheers,
Ins