[EVALUATING / NO BUG] Almost impossible to stall ?

[CoBlue]

Latest patch 1.2.15 .

Advanced Flight Maneuvers at speeds over 4-500 km/h. With ARU System on or off.

The airplane is almost impossible to stall, no matter how hard you pull on the stick. The AoA remains in yellow no matter what. Sometimes the AoA will only reach half of the yellow marker even if pulling max stick. Thus can't utilize the whole flight envelope.

It's like flying in "game mode". The new FM is too easy & has changed so dramatically from the previous build (if you wasn't careful you stalled out easily) now it's the opposite?

 

Also roll rate in a clean configuration is much slower then before ?

 

See thread http://forums.eagle.ru/showthread.php?t=139717

Thanx;)

Edited March 12, 2015 by Cobra847

[archer86]

I realized the same.

there is no danger with 1.2.15

[mytai01]

I never really found it easy to stall before the update, but it could be done with dramatic effects. I've always had problems with not breaking the gear on landings. I'll have to check this one out myself! :book:

[Golo]

I have to agree.

One other thing I tested after update was spins and as of now they dont behave like manual said they should. Now it just sets into flat spin.

 

Before the update there were characteristic 3 axis oscilations just like manual said.

 

I dont know what changed in FM, but this just isnt MiG-21 anymore :cry:.

[CoBlue]

I have to agree.

One other thing I tested after update was spins and as of now they dont

behave like manual said they should. Now it just sets into flat spin.

Before the update there were characteristic 3 axis oscilations just like manual said.

I dont know what changed in FM, but this just isnt MiG-21 anymore :cry:.

Agreed, sadly not the same Mig-21 anymore

Is this a bug ? can the devs please comment on the new FM ?

[Harle]

Agreed, sadly not the same Mig-21 anymore

Is this a bug ? can the devs please comment on the new FM ?

 

Yeah, right! Cobra, say something!:bounce:

[Manuel_108]

She stalls just fine imo and I can still get her in the red AOAs easily.

[Harle]

She stalls just fine imo and I can still get her in the red AOAs easily.

 

Not fine enough compared to the previous FM.

[Hook47]

We need a response from LN on this, what is the deal? I agree with the above.

[chn6]

I need Stall and Spin..

[Big Nuts]

Yeah me too, is it safe to assume the fm will be corrected?

[NeilWillis]

Is it also safe to assume it is now not more correct than it was before?

 

On what are you basing your findings? Gut feelings?

[Flamin_Squirrel]

Latest patch 1.2.15 .

Advanced Flight Maneuvers at speeds over 4-500 km/h. With ARU System on or off.

The airplane is almost impossible to stall, no matter how hard you pull on the stick. The AoA remains in yellow no matter what. Sometimes the AoA will only reach half of the yellow marker even if pulling max stick. Thus can't utilize the whole flight envelope.

It's like flying in "game mode". The new FM is too easy & has changed so dramatically from the previous build (if you wasn't careful you stalled out easily) now it's the opposite?

 

Also roll rate in a clean configuration is much slower then before ?

 

See thread http://forums.eagle.ru/showthread.php?t=139717

Thanx;)

 

If you're testing at speeds over 500km/h then you lack understanding of corner speed and its implications on achievable AoA.

 

Corner speed is the optimum speed to achieve the best instantanious turn rate; it also determines what will limit your turn rate. If you fly slower than this, you're AoA limited (full aft stick results in a stall). Flying at 500km/h+ you're likely faster than corner speed; as such you're G limited (a tight turn will result in you blacking out/breaking the plane before you stall).

[Cobra847]

The revised FM is still undergoing tweaks.

However, it is currently more accurate than it has ever been.

 

Whether control authority is not quite right is being evaluated, but if it is right, then it obviously won't be reverted.

[eekz]

I want to agree, imo stall and spin improved alot in 1.2.15. Nice progress LN!:thumbup:

[Golo]

I want to agree, imo stall and spin improved alot in 1.2.15. Nice progress LN!:thumbup:

 

Really, spins improved? Can you explain to me how?

Before, when you got MiG-21 into its characteristic spin oscilations and let go of controls it sorted itself out just like manual said.

Now when you get to the spin (flat spin since 1.2.15) and let go of controls, you can enjoy fall to your death.

It does not behave according what manual says at all.

[sissypilot]

Yes our beauty "ensure the most authentic MiG-21 experience ever created", wonderful but which one? The previous one which stalled each turn or this one which does not stall no matter what? Or the next one?

[Dolphin887]

Noted, will be fixed, however, for the IAS>600 km/h read the manual and Flamin_Squirrel post.

 

Thank you.

[CoBlue]

Noted, will be fixed, however, for the IAS>600 km/h read the manual and Flamin_Squirrel post.Thank you.

Hello Dolphin887,

Can we expect an FM update for v1.5?

Thanx!

[Maverick Su-35S]

I need Stall and Spin..

 

You need stall and spin?

 

First off, make sure your pitch trim and indicated airspeed (IAS) combination allows your AoA to go beyond the red mark on the AoA indicator when you pull full aft stick, cause no matter how slow you fly, if the trim is pretty much pitched down, you can barely reach the yellow mark on the AoA with full aft stick, so you must trim to pitch up as much as needed in order to go beyond stall AoA with full aft stick.

 

It was the trim that didn't allow most of you guys to have full pitch up elevator travel in order to overshoot the critical/stall AoA.

 

To induce a spin, you must simply use cross-controls (aileron and rudder inputs opposite to each-other) and a yaw rate will develop opposite to your aileron and towards your rudder.

 

In order to get out of spin, use cross-controls in the opposite direction now, having the stick (aileron) towards the spin and the rudder opposite to spin and you'll stop the spin.

[Maverick Su-35S]

Is it also safe to assume it is now not more correct than it was before?

 

On what are you basing your findings? Gut feelings?

 

YES! It is safe to assume it is not more correct than it was before and even if generally seems more correct than it was before in some places, it is less correct at other important places.

 

I'm not looking to say this, but maybe I should mention that I'm an aerodynamicist, flight dynamics specialist and pilot and I know exactly what I'm saying!

 

The MIG-21, had very realistic pitch-yaw-roll couplings and oscillations at high AoA spins and lovely wing rocking at high AoA when almost no yaw rates were developed, among it's first patches (early when it came in DCS). These might've been modified a bit and have different values but are still present in some form and they might still be realistic.

 

The ONLY problems with it's FM at that time were the "stalled lift" which came to zero, the rolling moments that were too high due to aileron deflection at some AoA and the high reduction in pitch stability (tended to pitch up) immediately after the wings stalled.

 

When the wings stalled they produced 0 lift (you could tell that by the G load indicator returning to 0 when stalling) which is wrong. In real life, when a wing or even airfoil (infinite wing span wing) stalls beyond a certain AoA, it still provides lift, but only between 50..66% (depends on 2D/3D shape) of what it should've had if there was no stall and as the AoA continues to increase after stall, so should the G-load or lift should also increase with further AoA even through stall..., cause that's reality...!

 

Here's a picture for closer understanding of how lift develops with AoA between null lift AoA and 90 deg. AoA:

 

http://www.aerospaceweb.org/question/aerodynamics/q0194.shtml

 

It never hurts to learn aerodynamics now and then and you'll always learn that you could've known more...!

 

Another problem that I told above was the fact that with the wings stalled, the center of lift moved too much forward (relative to the CG position), making the plane almost become unstable and tended to pitch up a lot, but this was partially fixed, because when passing through about 10 more deg. of AoA beyond that of stall with the remnant pitch up momentum that was accumulated, the aircraft suddenly develops a high pitch down moment although your stick is still full aft...! No matter if you try to pitch rock up and down and then back up to pass beyond that "magic" AoA which tends to snap your nose down, you still can't pass it. It's like a wall that the AoA slams into. Indeed as the AoA continues to increase, so should the pitch down moment continue to increase as well, but that should be a smooth and nice transition to higher pitch down moment up to about 90 deg.AoA, yet it seems that somewhere around 30-35 deg. of AoA (real AoA better seen from outside the aircraft using smoke and not the AoA indicator which indicates much higher values than real) the pitch down moment is even higher than it should be at 90 deg. of AoA with full forward stick, for this kind of aircraft in particular.

 

These were 3 things that seems like were tried to be fixed, but it seems that one of them (the pitch moment due to AoA) turned even worse than it was and the lift due to AoA beyond stall isn't high enough because for example even if the airspeed is almost constant (doesn't drop much) and you pull the stick until you reach your maximum G-load/lift and continue to pull and increase AoA beyond stall, the G-load drops to about a quarter (25%) of the lift it had at critical AoA (keeping in mind that the airspeed didn't drop more than 8-10%), so it's still not enough. The lift or G-load should still be somewhere between 50-66% left after the stall developed.

 

 

P.S.: Stall has nothing to do with airspeed as most people tend to think it has or learned so and makes them not understand aerodynamics anymore..., in reality ONLY the AoA governs stalling up to supersonic speeds and only from there the stall occurs according to both AoA and airspeed.

[CoBlue]

YES! It is safe to assume it is not more correct than it was before and even if generally seems more correct than it was before in some places, it is less correct at other important places.

As an aerodynamicist, flight dynamics specialist and pilot, your knowledge is priceless to DCS community:thumbup: I Hope LN will listen to you;)

[CoBlue]

Now in 1.5 you have to keep an watchful eye on the AoA at speeds (<600 km/h) when hard maneuvering, or you'll stall if not careful!

The whole flight envelope can be taken advantage of.

Thanx & Good job LN :thumbup:

Edited November 16, 2015 by CoBlue