sevenheavy
Posts: 927
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Leveld B763 - Needs Too Much Power?

Wed Mar 26, 2008 2:26 pm

Hoping for some opinions on this one....

I've had the LevelD B763 for a couple of years and I've just gone back to using it after a while on PMDG stuff. I can't remember whether it was like this all along but it seems to me that an unrealistic amount of thrust is needed when taxiing on the ground. Even at relatively light weights 45-50% N1 is required to get the aircraft moving and this goes up to almost 60% when at MTOW. Even take off thrust seems excessive - derated take offs are much more sluggish than I believe they should be and I'm using 110% just to get airborne

I'm wondering if I have unwittingly done something to the FDE?. Does anyone else think the same or has had a similar issue? is there a way to adjust the power settings within the aircraft.cfg?

I remember from a thread on here (which I now can't find!!) of an update for the FDE to increase the power when using reverse thrust. I updated my FDE accordingly and I wonder if this could have influenced any other power settings.

Grateful for any opinions or suggestions.

Regards
So long 701, it was nice knowing you.
 
Qantas744er
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RE: Leveld B763 - Needs Too Much Power?

Wed Mar 26, 2008 4:56 pm

Hey, use to feel the same when I started off with my PMDG and LDS planes. And for the taxi thrust there is a simple answer. Microsoft simply did not create a very good friction module for fs2004. This means the tires suffer from higher friction then they should. Requiring more thrust then they really should to taxi.

For your takeoff during a derated TO it will feel a little weak on TO depending from your TOW but since that allways changes there is no general power setting you should use. Look for a takeoff performance calculator for the LDS763 were you can enter weight, wind, pressure, temp and the specific airport and runway and the prog will tell u what de rate and assumed temp to use. It can even give you the optimal flap setting and tell you approx. How much runway you will need.

The 763 has a lot of power and even at MTOW at most conditions full thrust should not be required. BTW do you only derate or also use a assumed temp. ? Do you use TOGA on TO?

And don't change anything in the .cfg except for the power of the engines in lbs. What I do is check under the FAA TCDS for the specifc thrust on a certain engine I am flying on that airline and the. Enter it in the aircraft.cfg for that flight to make it as realistic as possible.

Excuse my spelling but written from my iPhone.

Leo
Happiness is V1 in Lagos
 
Ryanair737
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RE: Leveld B763 - Needs Too Much Power?

Wed Mar 26, 2008 8:03 pm

I think you might have done something to the FDE without knowing, on very light weights my Leveld 767 doesn't need any thrust to start moving and when heavy only needs about 40-45% I would say which is true to the real thing.

I would check your settings out.
LAST FLIGHTS= Ryanair LPL-BGY-LPL - EI-DPS/DWV - MAY 08 // NEXT FLIGHTS= TBC
 
sevenheavy
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RE: Leveld B763 - Needs Too Much Power?

Wed Mar 26, 2008 10:45 pm

Thanks guys- Ryanair - the figures you quote are more in line with what I remember.

My next question is, are there any obvious places to start to find the problem with the FDE? I have limited experience of updating the .cfg's but I am familiar with the process.

Regards
So long 701, it was nice knowing you.
 
David L
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Joined: Tue May 18, 1999 2:26 am

RE: Leveld B763 - Needs Too Much Power?

Wed Mar 26, 2008 10:50 pm



Quoting Qantas744ER (Reply 1):
This means the tires suffer from higher friction then they should. Requiring more thrust then they really should to taxi.

Wheel bearings, surely? Tyres should offer as much friction as possible. In any case, other publishers seem to have worked around it.

Quoting Qantas744ER (Reply 1):
For your takeoff during a derated TO it will feel a little weak on TO depending from your TOW but since that allways changes there is no general power setting you should use. Look for a takeoff performance calculator for the LDS763 were you can enter weight, wind, pressure, temp and the specific airport and runway and the prog will tell u what de rate and assumed temp to use.

Doesn't the LDS 763 have an FMC to give a huge helping hand in such matters... assuming it's set up correctly?
 
cptspeaking
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RE: Leveld B763 - Needs Too Much Power?

Thu Mar 27, 2008 11:06 am



Quoting SevenHeavy (Reply 3):
My next question is, are there any obvious places to start to find the problem with the FDE? I have limited experience of updating the .cfg's but I am familiar with the process.

Re-installing the airplane would probably be your best bet...

I hadn't flown the 763 in a while and when I got on the other night, it was all screwy, and I only had the default Level D 32 bit textures, and nothing else...did a re-install of the 763 and it was fine after that...just had to reinstall my add-on textures again and it was good to go...
...and don't call me Shirley!!
 
QFA380
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RE: Leveld B763 - Needs Too Much Power?

Fri Mar 28, 2008 8:36 am

I also often feel that the Level-D might have something up, it does take quite a large amount of thrust just to get it moving. I normally just throttles to the metal though for take-offs, don't really care how much virtual fuel I'm using.

Quoting David L (Reply 4):
Doesn't the LDS 763 have an FMC to give a huge helping hand in such matters... assuming it's set up correctly?

The FMC doesn't figure that stuff out for you, it just allows you to enter it and then it will control the power during take-off. Real pilots I assume either work this out for themselves with runway length, weight and atmospheric conditions in those massive flight manuals or they have a special calculator or they might just ask dispatch.
 
David L
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RE: Leveld B763 - Needs Too Much Power?

Fri Mar 28, 2008 9:55 am



Quoting QFA380 (Reply 6):
The FMC doesn't figure that stuff out for you, it just allows you to enter it and then it will control the power during take-off.

I'm not saying it does it all for you, I'm saying that if you use it properly, you remove a lot of extra work.
 
Ryanair737
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RE: Leveld B763 - Needs Too Much Power?

Fri Mar 28, 2008 12:54 pm

All the FMC does with regards to thrust in the 757/767 it allows you to enter your takeoff thrust temperature and that is about it. The Thrust Management System (TMS) near the engine display does the majority of the thrust management in the 757/767.
LAST FLIGHTS= Ryanair LPL-BGY-LPL - EI-DPS/DWV - MAY 08 // NEXT FLIGHTS= TBC
 
David L
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RE: Leveld B763 - Needs Too Much Power?

Fri Mar 28, 2008 5:06 pm



Quoting Ryanair737 (Reply 8):

I guess I've been spoiled by the PMDG 744X.  Smile
 
Qantas744er
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RE: Leveld B763 - Needs Too Much Power?

Fri Mar 28, 2008 6:17 pm



Quoting David L (Reply 4):

Doesn't the LDS 763 have an FMC to give a huge helping hand in such matters... assuming it's set up correctly?



Quoting David L (Reply 7):

I'm not saying it does it all for you, I'm saying that if you use it properly, you remove a lot of extra work.

There is a difference bewtween a de-rated takeoff and a takeoff with assumed temp. + a de-rated setting. A normal de-rate being chosen from the FMC will not be even close to optimal for the takeoff .

Pilots use only the minimum thrust required for their takeoffs. This to save fuel, wear to the engines etc. This minimum thurst is a combination of assumed temp and a de-rated setting. But the FMC cannot give you this data. So it is calculated by the crews with either charts, dispatch over ACARS (thats how its mostly done in the US) or by having laptops with the software on them.

For example at x weight x wind x temp on x runway length with xobstacles the plane requires 1.30EPR to complete the TO successfully the 2 de-rate options in the FMC will give you 5% 10% and de-rate for example. 5% might give you 1.52EPR 10% 1.41EPR This because these de-rate settings rely on the real outside temp which at full takeoff thrust might give you 1.60EPR at x temp. So why not use a assumed temp.? This will get you the closest to 1.30 EPR together with a de-rate setting.

Quoting David L (Reply 4):
Wheel bearings, surely? Tyres should offer as much friction as possible. In any case, other publishers seem to have worked around it.

Wrong. Tyres will offer a certain friction. But when friction is too much then the plane will of course require more thrust to get it rolling then in real life. And this is exactly the problem with FS2004 the friction is much too high. My proof is that with a PW4056 744 such as UA,SQ,MH etc. operate (i have changed the thrust setting in the .cfg to match the thrust of the PW4056 so 56,750Lbs as to the 58,000Lbs it currently has for all 3 models as this is the max. thrust provided by the GE CF6-80C2BF1) When at MTOW i need 42-45% N1 to get my plane rolling and then around 41 to 42% to keep it going.

Philsquares, member of this forum and SQ 744 captain also flying with PW4056 engines stated how using more than 40% N1 on the 744 for taxi is pretty dangerous as the exaust temps. get very high.

Try the same!

Other example, a real 737 will roll foward slowly at low weights and idle thrust. Take the PMDG 737 at a low weight hit F1 to make sure you really are using idle thrust (incase you have a throttle quadrant etc.) and check if the plane rolls foward. Again this wont happen.

As it seems the issue with the thread starters 763 is related to a bad? FDE update then it does make sence. But if you would like to have a better and more detailed read about the issue with the friction in FS2004 just google it up. There is even a alternative .dll that someone created requiring a more realistic thrust setting for taxi, but as the LDS and PMDG developers have confirmed this creates a whole bunch of other unrealistic issues with brake distance etc. as the brakes on the LDS and PMDG planes have been adapted to be realistic even with the increased friction that FS2004 creates.

Leo  Smile
Happiness is V1 in Lagos
 
sevenheavy
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RE: Leveld B763 - Needs Too Much Power?

Sat Mar 29, 2008 11:01 am



Quoting Qantas744ER (Reply 10):
My proof is that with a PW4056 744 such as UA,SQ,MH etc. operate (i have changed the thrust setting in the .cfg to match the thrust of the PW4056 so 56,750Lbs as to the 58,000Lbs it currently has for all 3 models as this is the max. thrust provided by the GE CF6-80C2BF1) When at MTOW i need 42-45% N1 to get my plane rolling and then around 41 to 42% to keep it going.

How do you go about changing the .cfg's? Do you create a seperate one for each engine type or just amend it each time you fly a particular type?

Thanks
So long 701, it was nice knowing you.
 
Qantas744er
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RE: Leveld B763 - Needs Too Much Power?

Sun Mar 30, 2008 5:36 pm

hey sevenheavy, all I do is change it for the particular flight, but it only takes 5 seconds and I hardly need to change it. And knowing the max thrust ratings by heart is even better. If you need some for certain operators on the PMDG 737/744 or LDS 763 I will tell you what airline uses what engine at what thrust rating. Feel free to ask.


Leo
Happiness is V1 in Lagos
 
David L
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RE: Leveld B763 - Needs Too Much Power?

Sun Mar 30, 2008 5:48 pm



Quoting Qantas744ER (Reply 10):
Wrong. Tyres will offer a certain friction. But when friction is too much then the plane will of course require more thrust to get it rolling then in real life.

If you reduce the tyre friction you risk slipping. Tyres are designed to offer as much friction with the surface as possible. Wheel bearings are designed to have as little friction as possible. To take an extreme example: if tyre friction was zero, you'd have no traction on the runway, therefore no directional stability if there was even the slightest camber on the taxiway/runway and your brakes wouldn't do anything either. If the wheel bearing friction is too high, on the other hand, you'll need more thrust to get moving.
 
cptspeaking
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RE: Leveld B763 - Needs Too Much Power?

Sun Mar 30, 2008 9:23 pm



Quoting David L (Reply 13):

I started to post yesterday about this, going into the differences between static and dynamic friction, then I thought I could probably spend my time better  Smile
...and don't call me Shirley!!
 
David L
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RE: Leveld B763 - Needs Too Much Power?

Mon Mar 31, 2008 10:41 am



Quoting CptSpeaking (Reply 14):

I thought of referring to the notorious Conveyor Belt thread but thought better of it.  crazy 

Qantas744ER: there might be a property which MS calls tyre friction but, if it's "too high", it can't actually be tyre friction - that's all I'm saying.  Smile
 
Qantas744er
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RE: Leveld B763 - Needs Too Much Power?

Tue Apr 01, 2008 5:16 am



Quoting David L (Reply 15):

Qantas744ER: there might be a property which MS calls tyre friction but, if it's "too high", it can't actually be tyre friction - that's all I'm saying. Smile

Regarding the actual tyre friction i was 100% wrong and you are 100% right. Thats just what the file is named that creates the issues in FS9.

I stand corrected!

Leo  Smile
Happiness is V1 in Lagos
 
David L
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RE: Leveld B763 - Needs Too Much Power?

Tue Apr 01, 2008 11:03 am



Quoting Qantas744ER (Reply 16):
Regarding the actual tyre friction i was 100% wrong and you are 100% right.

I'd say we both had valid points. The difference is that you were dealing with the issue under discussion and I was being pedantic.  biggrin 

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