Mike, have you also tried it out? Any problems or issues?

 

No, Nandan, but I will give it a try this evening. Very curious to see if there really is a problem.

 

Mike

Hi Nandan,

 

First off thanks for tackling such an ambitious project... I've enjoyed using your first merge and look forward to using your new ones...

 

I didn't get as much time as I would have liked - but - I did a few takeoffs with your PW variant - and - I didn't get the bad proposing... I didn't change any load outs - just used the package as it came... I'll try to get some time next weekend to do some more testing...

 

Thanks,

Scott

Hi everyone,

 

I did some experiments with the RR 200ER version. When heavily loaded - @ 600,000 lbs - at FL385 or so, it sometimes rocked from side to side. It seemed to be set off by things like changing the scenery density, especially going from heavy scenery (sliders to right) to light scenery (sliders to left). It was much worse at low scenery settings. Switching views may do it too. I observed some moderate porpoising but not often and I couldn't reproduce it. I decreased the "empty_weight_roll_MOI=" setting in the Aircraft.cfg file from 17000000 to 12000000, and it appeared to greatly reduce the rocking from side to side to a negligible level (the kind of thing that often happens momentarily when the scenery or view is changed, or the sim is unpaused).

 

Dangerous if you don't know exactly what you are doing. Strongly recommend novice users not try this

 

+1. Be sure to back up the air file if you try to edit it.

 

Do you have the VC merged for this one? If yes what should I do to make the VC show up?

.

 

Nandan is using the newer SkySpirit models that don't have a VC. You would have to go back to the older Opensky models.

 

Mike

What exactly do you guys mean when you say "the plane is bouncing up and down at cruise level" ? Like does it climb a few feet, then descend etc? Is it during the climb?

 

Thanks,

Nandan

Hi everyone,

 

For me, the plane is boucing in the last part fo the climb, if i have to reach FL400, the plane start to bounce around 36500 feet, nose up and down from 5º to 15º, 15º to 5º, all time, when I reach FL400, the plane is stabilized.

 

B777-200ER PW

Payload: 78592 lbs

ZFW = 392.592 lbs

Fuel: 41410 lbs

TOW: 434.002 lbs

 

 

Thanks.

 

Javier.

Javier, thanks for posting your exact load info.

 

B777-200ER PW

Payload: 78592 lbs

ZFW = 392.592 lbs

Fuel: 41410 lbs

TOW: 434.002 lbs

 

 

I copied the 200ER PW version to my aircraft folder, set the fuel and payload as above, started at FL350, and I didn't see any problems except for a small amount of side to side rocking that stopped by itself. I tried changing the scenery density from low to high and back.

 

BTW, climb at this altitude was only about 600ft/min, which seems reasonable at this high altitude.

 

Javier, if you feel like experimenting, try changing the ""empty_weight_pitch_MOI = " parameter in the aircraft.cfg file up or down by 5,000,000 or so and see if it has any effect.

 

Mike

Hi!, Mike777, thanks for the reply, I'll try this.

Mike, do you want people to change "empty_weight_roll_MOI=" or "empty_weight_pitch_MOI =" or both? I have searched heaps, and can't find a definitive answer to what these parameters do. Can you or someone please explain what each of the MOI parameters do (the empty_weight_roll_MOI= & empty_weight_pitch_MOI =)?

 

Cheers,

Nandan

Mike, do you want people to change "empty_weight_roll_MOI=" or "empty_weight_pitch_MOI =" or both? I have searched heaps, and can't find a definitive answer to what these parameters do. Can you or someone please explain what each of the MOI parameters do (the empty_weight_roll_MOI= & empty_weight_pitch_MOI =)?

 

"MOI" is "Moment of Inertia", or the resistance to motion. There is one for each axis of rotation, roll (side to side), pitch (forward and back -- changing might fix "porpoising"), and yaw (horizontal rotation around the vertical axis -- what the rudder makes the aircraft do). I only reduced the Roll MOI number (from 17000000 to 12000000) and it appeared to greatly reduce the rocking from side to side. I didn't experiment with the Pitch MOI as I have hardly seen the porpoising problem. But I am thinking it might help for those who do. I just experimented -- it's very easy to do, reload the same situation file, and see what happens.

 

I'm attaching the discussion of MOI from the FS9 SDK, which is available through links here (the Aircraft Container section is what you need):

http://support.microsoft.com/kb/555857

 

The MOI section of the SDK is attached as a pdf.

 

Mike

Hi everyone!!

 

I changed this parameters:

 

empty_weight_pitch_MOI = 13000000 (original 23000000)

empty_weight_roll_MOI = 7000000 (original 17000000)

 

I realized two flights:

 

Tokyo - Hiroshima (the same configuration)

Cruise altitud: FL400

 

B777-200ER PW

Payload: 78592 lbs

ZFW = 392.592 lbs

Fuel: 41410 lbs

TOW: 434.002 lbs

 

All was perfect. No boucing.

 

Second flight:

 

Paris - Tokyo

Initial cruise altitud: FL330

 

B777-200ER GE

Payload: 54927 lbs

ZFW: 368927 lbs

Fuel: 228500 lbs

TOW: 597427 lbs

 

Three step climb: FL330 to FL350

FL350 to FL370

FL370 to FL390

 

All was perfect, except the last s/c, around FL382 to FL390 the plane start to nose up, nose down, disconect VNAV and conect V/S to 900 fpm, the plane stabilizes and reach to FL390 corectly.

 

The rest of the flight was OK. descend an land OK.

 

Thank you to all for the advices, for me, all is ok, this is a minor issue, I continue to experiment. If I find something, i'll tell you.

 

Thanks again for this merge to Boeingsta, this is a great job, and thanks to Mike777 for the advices.

 

Javier.

All was perfect, except the last s/c, around FL382 to FL390 the plane start to nose up, nose down, disconect VNAV and conect V/S to 900 fpm, the plane stabilizes and reach to FL390 corectly.

 

The rest of the flight was OK. descend an land OK.

 

Hey!

 

When you say "nose up, nose down", by nose down, do you mean you descended? Or was it just levelling off to gain some speed, because that happens to my aircraft a bit.

 

Did you use VNAV for the descent?

 

As a general rule of thumb, if anyone is wondering, is calculate the Top Of Descent (first 2 digits of your cruise level, e.g. 31000, use 31), multiplay by 3, add 3NM on. Then use Flight Path Angle and crank it to -3.2. This should get you neatly at the desired altitude you want too.

 

If you need to fly to a certain altitude by a waypoint, then use: (flight level - desired altitude by waypoint) x 3 + 3. E.g. FL310, need to be 10000ft by certain waypoint: (31-10)x3 +3. -3.2 Flight Path Angle.

 

Let me know if when you changed the MOI's if VNAV worked for you. Because the VNAV isn't good on the PSS, unless you've programmed it into the FMC correctly. I don't trust it. Just let us know if the changing of MOI's did any good. It'd be awesome if it fixed the problem :lol:

 

Thanks,

Nandan

Hi everyone!, thanks Nandan for the reply.

 

When the plane "nose up, nose down" (bounce) is always when I climb, the plane maintain the climb, but all time the nose is "up and down"

 

When I changed the MOI's, the VNAV works a lot better, the "bounce" of the plane almost gone, in this week, I realized two "Paris-Tokyo" and two "Tokyo-Paris" and only in one, the plane bounced, to climb from FL382 to FL390, but i disconect VNAV and i connect V/S at +900 fpm and the plane reaches good to FL390, I think that the "bounce" in this flight was due I had a little more fuel (around 13000 lbs more) that in others flights, because the others flights with less fuel, all was ok, I complete the flights (12 hours) without problems. I'll to investigate this, if I discover something, I'll tell you.

 

Thanks.

 

Javier.

 

P.S. I can't wait for the B777-330ER !! Let's go!!

 

Sorry for my poor English.

Oh sweet. Extra fuel shouldn't cause bouncing i would imagine.

 

Mike777 you said the rolling side to side only happens when you switch between dense and light scenery and such, is this true? Does it happen in flight? I get the side to side rolling when i un-pause sometimes. But i think this is normal. It doesn't happen to me during flight. I might reduce the MOI pitch and roll values by 5,000,000 just to bring it closer to the calculated value which i obtained from using the formula given in the FS9 aircraft container.

 

Nandan

Mike777 you said the rolling side to side only happens when you switch between dense and light scenery and such, is this true? Does it happen in flight? I get the side to side rolling when i un-pause sometimes. But i think this is normal. It doesn't happen to me during flight. I might reduce the MOI pitch and roll values by 5,000,000 just to bring it closer to the calculated value which i obtained from using the formula given in the FS9 aircraft container.

 

Nandan,

 

I'm not sure it happens spontaneously. It did happen (until I lowered the value for Roll MOI by 5000000) if I switched views or changed scenery settings. It wasn't "normal" in that it didn't stop right away. I know that momentary vibrations of various sorts can happen when the view or scenery density is changed (or even alt-tabbing in and out of Windows in full screen, or unpausing a flight), but this kept going -- the aircraft wasn't stable.

 

It seems that decreasing the Roll MOI and Pitch MOI worked for Javier, and lowering the Roll MOI worked for me (I never had much porpoising), so I think you are on the right path.

 

Mike

Hey everyone!

 

Just like to update you on anything ive been doing on the merge. Currently i have reduced the MOI pitch and roll values by 7,500,000 (7.5 million) and it's working great! I didn't have a rocking problem to begin with but i changed the 2 values anyway and it's working well :biggrin: .Bring both values down even if you only had a problem with 1 parameter (ie if you only had a problem with roll, still bring both down). This is so the values are closer to the calculated values which were calculated using the equation in the FS2004 container SDK.

 

So try it out guys! And tell us how it goes! ^_^

 

Nandan.