Shifting Center of Gravity (weight and balance)

[hitman]

Weight and balances on an aircraft are extremely detrimental to a stable flight, and more so on heli's. I have a few questions to ask about this:

 

1) Will CG be static or dynamic in BS? Obviously with weaps release the CG will change, but what about fuel bladders? Hydraulic fluid? Also pertains to question 2.

 

2) Is fluid dynamics figured into the simulator? Fuel leaks into separate compartments, hydraulic fluids being dumped overboard, ballast, liquid sloshing in half-filled reservoirs?

 

3) Kind of a dumb question, but would there be a way to load the aircraft in such a manner to make it unstable in certain flight characteristics? (flying forward with tail heavy tendency makes it harder to lower the nose and accellerate, a means to adjust tail heavy a/c to nose heavy)

 

Please dont refer me to the FAQ, this is just to go a little bit more in-depth. Yes, no, and maybe are excellent answers, will accept an either/or statement too.

[EvilBivol-1]

1) Will CG be static or dynamic in BS? Obviously with weaps release the CG will change, but what about fuel bladders? Hydraulic fluid? Also pertains to question 2.

Yes, the CG is dynamic and will change as the stores/fluids/airframe structure are affected in real time. Whether the change will be enough to you to appreciate it, however, is another question. (Opps, see Alpha's response below).

2) Is fluid dynamics figured into the simulator? Fuel leaks into separate compartments, hydraulic fluids being dumped overboard, ballast, liquid sloshing in half-filled reservoirs?

The available pressures and flows of the fluids are modeled dynamically and mainly within their respective systems (e.g. the fuel system <-> engine <-> APU, etc.), including pressure dependencies, pumps functionality, etc. The fluids themselves are not modeled according to fluid dynamics.

3) Kind of a dumb question, but would there be a way to load the aircraft in such a manner to make it unstable in certain flight characteristics? (flying forward with tail heavy tendency makes it harder to lower the nose and accellerate, a means to adjust tail heavy a/c to nose heavy)

I don't think you can configure the aircraft for instability. However, damaging the airframe can be fun. Edited August 23, 2008 by EvilBivol-1

[AlphaOneSix]

These kinds of things are taken into account during aircraft design so that they are not a big issue:

 

The weapons are already generally lined up with the CG, so firing them off does not appreciably change the CG (that I can tell).

 

The fuel tanks are arranged in such a way that the CG does not change appreciably as fuel drains out of them.

 

The total amount of hydraulic fluid on the aircraft is not heavy enough to cause a noticeable shift in CG. Besides, if you lose all of your hydraulic fluid, you have much larger concerns.

 

The aircraft isn't really watertight, so if there is hole big enough for fuel to leak, it will leak out of the aircraft, not redistribute itself around the aircraft.

 

The fuel tanks have baffles in them to prevent sloshing that would alter the CG of the aircraft.

 

To try to answer your third question, using normal loading, there isn't any way to get the Ka-50 out of CG limits. The only possible thing I can think of would be to fill one of the fuel tanks (aft or forward) and leave the other one empty, but even then I am not sure if that would be sufficient to throw the aircraft out of CG limits.

 

I think the only way to really get the aircraft out of CG would be to have part of it shot off. ;)

Edited August 23, 2008 by AlphaOneSix

[Yo-Yo]

One more addition: the landing gear position up/down moves CG as well. And one can notice it while hovering or even flying.

 

And by the way - gear retracting mechanics (kinematics) is modelled coupling with the hydro system so if you try to retract gear while the helo flying with a g>1 it will be difficult to fully retract the landing gear.

[VMFA117_Poko]

^^ Amazing. Im so hungry to finally see this that my teeth have grown to ground.

[d0ppler]

Weight and balances on an aircraft are extremely detrimental to a stable flight, and more so on heli's.

 

due to my experience with radio controlled aircrafts, fixed wing aircrafts are far more prone to changes in c/g than helicopters. I can mount a 2lb camera in front of my .50 size heli without any problems hovering and manouvering it. That would be impossible with an eqvivalent fixed wing aircraft.

[hitman]

due to my experience with radio controlled aircrafts, fixed wing aircrafts are far more prone to changes in c/g than helicopters. I can mount a 2lb camera in front of my .50 size heli without any problems hovering and manouvering it. That would be impossible with an eqvivalent fixed wing aircraft.

Not necessarily. If you put the weight on the helicopter underneath the rotor shaft, the CG will not be affected. Larger aircraft are able to carry a lot more weight than most helicopters, although there are some helis that do carry TONS of cargo. Even those helis have to watch their CG very closely. A small shift in CG can throw a heli out of balance quite easily.

[monotwix]

Unmanageable pilots weight.

http://www.youtube.com/watch?v=iGvut-vpi0M

[mvsgas]

This is what happens when you don't pay attention to CG

The aircraft was undergoing a Phase inspection and the removed to many components from the front.

[CAT_101st]

Unmanageable pilots weight.

http://www.youtube.com/watch?v=iGvut-vpi0M

 

 

The pilot was just a idot. and had never flown a choper. at the end yo can here a guy say that he was never checked out in it and did not know how to fly it. the pilot just wasted 26K for a pride thing.

[hitman]

No, the guy announced he had no time in that type aircraft. Every heli handles differently, and the fact that he managed to get it up in the air told me he knew roughly what he was doing. He was still an idiot, though..

[hitman]

One more addition: the landing gear position up/down moves CG as well. And one can notice it while hovering or even flying.

 

And by the way - gear retracting mechanics (kinematics) is modelled coupling with the hydro system so if you try to retract gear while the helo flying with a g>1 it will be difficult to fully retract the landing gear.

That sounds pretty interesting...Ive yet to come across any helis that didnt rely on skids or downlocked landing gear. (the heli with Accelleration doesnt count cuz I dont fly it.)

[monotwix]

The pilot was just a idot. and had never flown a choper. at the end yo can here a guy say that he was never checked out in it and did not know how to fly it. the pilot just wasted 26K for a pride thing.

 

 

I guess that if you were a fat bustard or a skinny snot or a pilot who can’t be told what to do, it wouldn’t have mattered for the gyro brick manoeuvres where’s a good flight configuration can go a long way.

This principal doesn’t work well for the figure of speech apparently,

 

Well I believe it does, it just takes some effort to do any thing.

[Zorrin]

No, the guy announced he had no time in that type aircraft. Every heli handles differently, and the fact that he managed to get it up in the air told me he knew roughly what he was doing. He was still an idiot, though..

 

 

From his "ability" to fly the Schweizer I'd have said he has NO time in Helis at all.

 

Every car handles differently, as does every aircraft. However the fundamentals are the same.

 

You pull the lever and depending on where the Heli was built it'll either swing to the left or the right.

 

Now if he had any time in helis he'd have known that...

 

He certainly didn't have a full license and at most 10 hours instruction.

 

The only reason he got it into the air was because he didn't know how to stop it. You can see when it just starts spinning he's pulling in more collective and no pedal....

[monotwix]

From his "ability" to fly the Schweizer I'd have said he has NO time in Helis at all.

 

Every car handles differently, as does every aircraft. However the fundamentals are the same.

 

You pull the lever and depending on where the Heli was built it'll either swing to the left or the right.

 

Now if he had any time in helis he'd have known that...

 

He certainly didn't have a full license and at most 10 hours instruction.

 

The only reason he got it into the air was because he didn't know how to stop it. You can see when it just starts spinning he's pulling in more collective and no pedal....

 

 

He already knows that, his quest was to know more about the central gravity forces simulation to have an idea of the sim.

As I see it there’s no need to make the point of the physics for this nature.

Edited August 24, 2008 by monotwix

[hitman]

Its not necessarily needed, but it is nice to know. :) Besides, I agree that pilot was stupid not to follow his instructors commands. It would have been a nice Darwin award.