Using Acufeel with PMDG airplanes will certainly shake the airplane if you overspeed, but I think it might also tuck the nose for you as well.

It certainly does!

 

I loaded an aircraft to 100,000,000 lbs for fun in FS - it flew normally.

 

Weight seems to make no difference to the flight dynamics. In fact, MS flight dynamics are a joke. Modern systems can do so much better than that (and for those that think a highly realistic flight model would hurt frame rate - you would be very much mistaken).

 

A few things to demonstrate how rubbish MSFS flight dynamics are:

 

* Try taking off with the *slats* retracted - should be impossible but it isn't.

* Deployment of slats at high altitude should result in violent pitch up - it does not

* Accelerating beyond critical Mach number should result in Mach tuck - it does not

* The stall speed at altitude is far too slow (in fact, MSFS does not correctly model AoA) - "coffin corner" is thus not modelled

* Accelerated stall is not possible

 

Best regards,

Robin.

Takeoff with slats retracted should not be impossible.

Accelerated stalls are simulated in FSX.

As is coffin corner.

 

I haven't tried selecting such a weight, but it may well be FSX ignores it as out of limits. The FSX aerodynamics model is simplified but the basic effects of weight and g are taken care of.

Woah what is Mach tuck?  I don't fly real world with mach so first I've heard of it.  I guess I can google.  In the NGX I do get coffin corner in certain circumstances.  Have PMDG somehow figured out a way to simulate this or will FSX not stall at the correct speed no matter what?  Is the ngx coffin cornering just a visual touch?  

 

At high mach numbers, shock waves start to form causing the centre of lift  to move aft. This causes a nose down pitching moment. That's it basically; it's been a while since I reviewed principles of flight in detail.

Flamin_Squirrel got it. You must take immediate action, as increase in Mach number only makes the problem worse, and is generally unrecoverable once it develops (the nose pitches down, only promoting the aircraft to accelerate further). It's often accompanied by control reversal, first in roll, but also in pitch, further adding to the recovery problem. Stab trim might need to be used instead. Control flutter can lead to failure in very short time.

 

Best regards,

Robin.

Flamin_Squirrel got it. You must take immediate action, as increase in Mach number only makes the problem worse, and is generally unrecoverable once it develops (the nose pitches down, only promoting the aircraft to accelerate further). It's often accompanied by control reversal, first in roll, but also in pitch, further adding to the recovery problem. Stab trim might need to be used instead. Control flutter can lead to failure in very short time.

 

Best regards,

Robin.

 

Many airliners actually cruise above Mcrit, so encounter some mach tuck. They're designed for it though, so it doesn't lead to control difficulty.

 

Those aircraft that aren't can obviously end up in serious trouble.

 

 

In case i abort before the V1 does the p,lane stop before the end of runway? and the opposite is if i try to abort the flight after V1 do i overshoot the runway? Of course u can say depends how far from V1 u abort the flight but i am simply curious about this performances. I know it sopunds stupid but it is just curiousity

 

A lot of factors goes into calculating V1. VMCG, MAX BRAKE(VMBE), VCEF, etc to name a few. Through performance charts and formulas, a given gross weight will equate to a critical field length. As long as the critical field length is shorter than runway available, and no other limiting speeds are exceeded(VMBE ), you can stop the aircraft above V1 and not exceed the runway. All depends on what speed V1 is based on. So basically when MTOW is limited by runway available(field length limited), you will exceed the runway if above V1. We used a procedure in the DC10 called takeoff into suspected windshear. We calculated V1, VR, and V2 for MTOW for the field conditions and for actual gross weight. As long as there was a 10kt split between both rotate speeds, We used the MTOW V1, VR, and V2 not to exceed a 20kt additive. In this situation, you are always limited by the MTOW speeds and would never exceed runway available.

 

 

 

@Alfrdo - VR is just the calculated speed to rotate in order to reach V2+10 at least 35 feet above the runway, you should be looking at Vmu or Vlo if you want to test if the aircraft actually lifts off around the correct speed for its gross weight.


I think it's just V2 at 35ft, and that's single engine with the other falling at V1.

 

In the aircraft I've flown, V2 or V2+10 will happen at 35ft. Depending if engine out V2 or all engine V2+10.

 

 

 

Many airliners actually cruise above Mcrit, so encounter some mach tuck. They're designed for it though, so it doesn't lead to control difficulty.



Those aircraft that aren't can obviously end up in serious trouble

 

At Mcrit there is a lot of drag. Most airliners are limited by the Mcrit. The DC10 had a max mach of .88. This is it's Mcrit. Even though it has no control issues above Mcrit, that's the max mach set by the FAA due to Mcrit. The DC10 has a design dive speed of .95 and was stable at that speed. The G5/550 and the Citation X has the same effect, but the max speed was set at Mcrit. The Lear would become uncontrollable due to the shock wave and flutter. Ever watch the shockwave dance on the wing? I see it alot on the G5. 

Ever watch the shockwave dance on the wing? I see it alot on the G5. 

 

No but I'd like to. Any chance of a jump seat ride?!

Very smooth :wink:

A video would be awesome, if you could? I'll settle for a ride in the back if not. :lol:

 

Best regards,

Robin.

Where are you all located? Would have to give ya a shout if I'm ever headed to your area and give you the nickle tour. I'll try to get a video. First time I saw it, I thought it was my eyes or something stuck to the window. I leaned in close to see what could be possibly stuck to and fluttering on the window. That's when I realized it was mid wing. Reminded me of the line that separates a pencil when it sits in a glass of water.

 

 

A video would be awesome, if you could?

 

 

Pretty visible in that one for a little bit in the beginning.

 

 

 

Where are you all located?

 

IAD - all my buddies send me messages when they fly through because I'll run them around town to hang out during their airport appreciation time.  haha.  Let me know if you're ever flying through.

Kyle, I get through BWI a lot . I'll shoot you a message when ever I fly through

Kyle, I get through BWI a lot . I'll shoot you a message when ever I fly through

 

Good deal.  I wouldn't mind getting up there sometime.  Last time I was up there was 2009 to take the AT-SAT...haha.

Where are you all located?

Basingstoke UK, so let me know if you're in the south of England any time!

KSC. (NOT the Florida one)

Not that many biz aviation goes on around here. Might very well be that the airport has yet to see a Gulfstream V/550.