Does HTC calculate CoG or use NASM documents for the Ta152?

[Mister Fork]

The CG is dynamically calculated as gas is consumed, bullets shot, bombs dropped ...

HiTech

I remember this exact question came up when we introduced the Dora back in early 2000's. It's all dynamic.

[colmbo]

The CG is dynamically calculated as gas is consumed, bullets shot, bombs dropped ...

HiTech

Then why doesn't it show a pitch trim change in Dawger's example?  CG certainly changes trim --- you can lean forward in a Cessna 152 and it will pitch down slightly.

[Dawger]

The CG is dynamically calculated as gas is consumed, bullets shot, bombs dropped ...

HiTech

If this is the case, then the fuel tanks are calculating exactly on the Center of Gravity at all times in the TA-152 that i flew because there is no trim change in the aircraft with fuel burn out of the forward or aft tank.

I did see a trim change burning left and right wing tanks in the TA-152 so one can assume that there is, a calculation being performed for lateral weight changes and the effect on roll moment.

[Zimme83]

 
In every real world airplane I have ever flown, even fuel tanks with a centroid on the center of gravity require adjustment of pitch trim with fuel burn. This is because the center of gravity is a POINT and fuel tanks are not POINTS.

Not really, whats matter is the center of gravity of the fuel tank, and that is a POINT...

[JunkyII]

If this is the case, then the fuel tanks are calculating exactly on the Center of Gravity at all times in the TA-152 that i flew because there is no trim change in the aircraft with fuel burn out of the forward or aft tank.

I did see a trim change burning left and right wing tanks in the TA-152 so one can assume that there is, a calculation being performed for lateral weight changes and the effect on roll moment.

I didn't watch your video (doesn't work for some reason) but how did you test forward vs aft tank and CG??

Did you test with the guns empty??? I feel like that is why you don't notice the nose being lighter as much.

[FLS]

...

Assumptions otherwise, despite evidence to the contrary, are erroneous.

The evidence indicates that the Ta-152 forward fuel tank is on the CG.

Then why doesn't it show a pitch trim change in Dawger's example?  CG certainly changes trim --- you can lean forward in a Cessna 152 and it will pitch down slightly.

Maybe because the Cessna is a 1,600 lb airplane instead of 10,000 lbs and the 200 lb pilot already sits in front of the CG?

[Dawger]

I didn't watch your video (doesn't work for some reason) but how did you test forward vs aft tank and CG??

Did you test with the guns empty??? I feel like that is why you don't notice the nose being lighter as much.

Test method is as follows:

Fuel burn times 10

Set power, turn of autopilot. Combat trim off as well.

Switch to desired tank. Burn until empty and see what happens. Not much happens in pitch burning any tank. Wing tanks do have an effect on roll.

[Dawger]

Not really, whats matter is the center of gravity of the fuel tank, and that is a POINT...

I have news for you.

Fuel is liquid.

While we must, for simplicity sake, treat the fuel tank as a single point (usually expressed in inches aft of datum or fuselage station) the reality is that fuel, being a liquid, does not behave as a point force on the aircraft.

Angle of attack will change the center of gravity as the fuel moves in the tank.

[Dawger]

The evidence indicates that the Ta-152 forward fuel tank is on the CG.

Maybe because the Cessna is a 1,600 lb airplane instead of 10,000 lbs and the 200 lb pilot already sits in front of the CG?

Or maybe its not.

You can feel a 120 lb flight attendant walking down the cabin in a 100,000 jet (in the flight controls, Anything else might be inappropriate). We could always tell when the boss was awake in the back by the watching the trim move. It amazed him that the flight attendant seemed to have some supernatural power.

I used to trim the Beech 18 nose down so I could walk to the back to get my lunch and still be within 100 feet of my altitude and that is a 10,500 airplane.

Real airplanes require constant trim in the pitch axis.

[Zimme83]

I have news for you.

Fuel is liquid.

While we must, for simplicity sake, treat the fuel tank as a single point (usually expressed in inches aft of datum or fuselage station) the reality is that fuel, being a liquid, does not behave as a point force on the aircraft.

Angle of attack will change the center of gravity as the fuel moves in the tank.

The TA had a rubber bladder inside the fuel tank which would prevent the fuel from moving around...

[FLS]

Or maybe its not.

You can feel a 120 lb flight attendant walking down the cabin in a 100,000 jet (in the flight controls, Anything else might be inappropriate). We could always tell when the boss was awake in the back by the watching the trim move. It amazed him that the flight attendant seemed to have some supernatural power.

I used to trim the Beech 18 nose down so I could walk to the back to get my lunch and still be within 100 feet of my altitude and that is a 10,500 airplane.

Real airplanes require constant trim in the pitch axis.

I'm  seeing a difference in lever arm compared to the Ta-152 fuel tank sitting on the CG.

[colmbo]

Maybe because the Cessna is a 1,600 lb airplane instead of 10,000 lbs and the 200 lb pilot already sits in front of the CG?

Because of some of your responses I have to ask...are you a pilot?  have you ever flown an airplane?

It doesn't matter where the pilot sits, the aircraft is trimmed....the pilot leaning forward changes the CG.

FYI in the Cessna 152 the arm for the passenger seats is 39 inches aft of datum, the permissible CG range is 31-36.5 inches aft of datum....the seats are behind the CG. 

 
The 200 pound pilot was a 120 pound pilot moving only his upper body...very tiny change in CG position yet there was a change in aircraft trim.

Flying the B-24 it was very noticeable when someone went to the tail....that's a 200 pound passenger and a 65000 pound airplane.

[colmbo]

The TA had a rubber bladder inside the fuel tank which would prevent the fuel from moving around...

The bladder would hold the fuel, a baffle would lessen it sloshing about.

[colmbo]

Not really, whats matter is the center of gravity of the fuel tank, and that is a POINT...

And that "point" might change position depending on the shape of the tank.

[FLS]

Because of some of your responses I have to ask...are you a pilot?  have you ever flown an airplane?

It doesn't matter where the pilot sits, the aircraft is trimmed....the pilot leaning forward changes the CG.

FYI in the Cessna 152 the arm for the passenger seats is 39 inches aft of datum, the permissible CG range is 31-36.5 inches aft of datum....the seats are behind the CG. 

 
The 200 pound pilot was a 120 pound pilot moving only his upper body...very tiny change in CG position yet there was a change in aircraft trim.

Flying the B-24 it was very noticeable when someone went to the tail....that's a 200 pound passenger and a 65000 pound airplane.

Hitech says it's modeled so if it's wrong how much is it off and in which direction should the trim change?