Jump to content

Sign in to follow this  
Guest Rwilson

744 climb

Recommended Posts

Guest Rwilson

all,i have the 747-400, and clibing is a difficulty..?I was climbing to reach FL350, but then my pitch decreased and my climbing stopped. I kept changing from VNAV to FL CHG and nothing happened. I had to dissconect the auto-pilot and do it myself, which lost my speed. I had to change the altimiter to FL320 instead. Then it took 5 minutes to reach MACH .860.What is happeneing?robbie

Share this post


Link to post
Guest fullflapsplease

Are you checking to see that your not bursting through your maximum flight level in the FMC on the VNAV page 2/3? This will give you your optimum and maximum flight levels for your current weight.If you're heavy and bursting your MAX ALT then what you say you're experiencing will happen.Cheers.Mark.747400.jpg

Share this post


Link to post
Guest Rwilson

there is no FMC message saying that. But i will check upon it...cheers,robbie

Share this post


Link to post
Guest fullflapsplease

I don't think you'll receive a FMC message about that, just check in the VNAV 2/3 to see what the ALT values are.Cheers.Mark. 747400.jpg

Share this post


Link to post
Guest Rwilson

thank you very much, materobbie

Share this post


Link to post
Guest s_L_Y_F_a

Do you use Active sky? If yes than this could be the problem since AS simulates high altitude winds and when you climb through the air you may get into a zone with a totaly different wind direction/speed than the wind you had before. For example if you where flying with headwind and suddenly the wind turned 180 degree and you got tailwind then your airspeed would of course decrease.And since VNAV is trying to maintain speed by changing pitch while having a constant thrust setting and as a result VNAV reduces pitch to regain speed.

Share this post


Link to post
Guest fullflapsplease

Yes, theabove can also be the case, a way to reduce this immediate impact is to select wind smoothing in FSUIPC, mine is at 1 degree and 1 knot per every 5 seconds, this helps the aircraft re-configure itself and maintain speed.Cheers.Mark.

Share this post


Link to post
Guest capntom

The proper way to climb the aircraft is in VNAV, it will take care of the climb speed, rate and airspeed as well as engine thrust. It is not however idiot proof as far as the matter of optimal and maximum altitudes. This information is available on page 2 of the V-NAV tab where CRUISE optimum and Maximum for your weight will be shown. These values will vary a bit for a given weight with the cost index assigned. A figure of 100 or 200 is a typical CI.Note that the IAS will decrease in a constant Mach climb, above about FL 260 Mach will be used for all performance and speeds. M0.84 is a typical climb number for a CI (cost index) of 100.As the plane is capable of carrying a tremendous weight of fuel and cargo, the altitude capability varys greatly with weight. At Max Takeoff weight, something on the order of FL300 would be a good initial cruise alt to select. Empty, with say, 100,000 kg fuel, you could climb straight away to FL380 with a fairly soon step to FL 400.The performance is optimized to be efficent in a very small range of speed and altitude for a given weight! Too low and fuel burn goes up, too high and she will get really sluggish. You should be able to climb at M 0.840 and level right away at that cruise speed, if you are getting slower, you are too high!Cheers: Tom

Share this post


Link to post
Guest Rwilson

thanks, but the problem is that it takes ages to climb. It's ridiculous. I haven't had one succsesful (excuse the spelling) flight since i got it, all down to the climb.There was a message in the FMC saying "max alt FL159". Why can't i go higher than that?I put 200 on the cost index when i was flying from heathrow to cape town.I had about 153.000KG of fuel, i reduced my load, so much that i didn't have any cargo because it said i was over wieght in the FS9 Fuel/payload menu.Is something wrong here?cheers,robbie

Share this post


Link to post

Well-well,Did you by any chance use FS native tools (fuel/payload) to set fuel and payload? Don't do that. Use PMDG's own fuel/payload manager and you will be all set.This tool should be somewhere in your Start Menu, where PMDG747 installed itself, but you will most probably be able to find it in the installation folder.Ignore me if you are using it already.Cheers,


Balint Nagy
 

Share this post


Link to post
Guest capntom

153,000 kg is a lot of fuel, enough to get ya from Chicago to Hong Kong! With typical empty aircraft weight you should have a tko wt of around 313,000 or so, pretty light compared to the all up weight of 393,693 kg.At that weight you should be able to climb to an initial altitude of FL 340 or so.Double check the fuel and cargo weights, in FS "fuel and Payload" under aircraft. Empty weight should run around 160,000 kg.Tom

Share this post


Link to post
Guest Rwilson

i do accualy use fuel manager and the load manager, but it still says the airplane is over wieght. So i adjust the payload. I can't have full cargo and full load af passengers because the plane would be over wieght.So i'm guessing the climb has something to do with the VNAV and fuel load? Plus, how much fuel would you recommend with a flight from heathrow to cape town?

Share this post


Link to post

Robbie,You are mixing apples and oranges! ;-) Check that you have Weight in kgs selected in the PMDG|General|Options menu Various tab.Also make sure your FS International setting is set to Metric (altitude in feet).Now you should be able to enter any weight anywhere in kilograms. (I really wish we could get rid of this imperial system...lol)Hope it helps,


Mats Johansson
PMDG Flight Test Dept
Boeing777_Banner_BetaTeam.jpg

| Asus Z270-A | Intel i5-7600K @ 4.8 GHz OC/H2O | nVidia Geforce GTX 1070 8GB OC/O2|

Share this post


Link to post

Robbie, I do not know right now how much fuel would be needed for such a flight, although I have recently completed a route just like that. It all depends on distance, payload, predicted wind direction and speed along the route, the distance of your alternate(s) and your choice of minimum landing fuel. I have made a decent little fuel planner for the 400 that will even tell you the fuel distribution among tanks, possible time until TANK/ENG and so on.You cannot have full pax and full cargo load as it will, indeed exceed the MTOW by some. Try, for instance full pax load with 4 to 6 palletts of cargo. Also, when setting up FMC, pay close attention to VNAV page 2 where, after input of fuel amount, ZFW and Cost Index, it will present you with OPT ALT, referring to the optimum cruise altitude given your current weight. Round up this value to the closest 1000 and enter it as your CRZ ALT. Also set this altitude on the MCP and after takeoff, turn VNAV on and let it manage thrust and climb in order to reach your altitude safely.Also, there is an extraordinary document made by Holger Seilz here:http://forums.avsim.net/dcboard.php?az=sho...13344&mode=fullGo and check it out. It's definitely worth the time, and most probably you will recognize the answer to your problem.Cheers,


Balint Nagy
 

Share this post


Link to post
Guest 747-NUT

Hi, First off all I don't really know the answer to this, but I will share some experiance with you.On ALL my flights so far the FS Fuel/Load Manager has claimed the aircraft is over weight. Even if the PMDG one states it's empty, with 2/3rds fuel. I have now removed all weight and fuel settings for the 747-400 in there for my favorite flights. Yet the FMC Set's Opt Alt to around FL300 she climbs to that, stays there and all is well, depending on load set in the PMDG Load Manager she often can go higher. Just depends on the trip.On some of my first long haul flights with full Pax, Cargo, and Fuel, V2 speed has been 185 Knots with 20 flaps.. :)I even had the Red Letters saying I was overweight. But she got of the ground (Just) and went on to fly 5hrs at FL2800 although I think I was above landing weight so I ended up dumping all but the minium amount of fuel to land or do 1 go around........ although I crashed on Approach, due to pilot error.... :) But the fact is she climbed to 28000ft with all that weight on boardSelect the Flight Director to on, before you depart. keep the Atificial Horizon on the pink Horizontal line, this will give you the best climb speed, for the given weight, if you want to fly it manually of course.I have had (Once, when I first got the plane) an Unable CRZ Alt in the FMC Display, but bringing it down a thousand feet or so seemed to work.YEEEEEEEE HAAAAAAAWWWWWW ;)Cheers.Matt.

Share this post


Link to post

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  
  • Tom Allensworth,
    Founder of AVSIM Online


  • Flight Simulation's Premier Resource!

    AVSIM is a free service to the flight simulation community. AVSIM is staffed completely by volunteers and all funds donated to AVSIM go directly back to supporting the community. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. Thank you for your support!

    Click here for more information and to see all donations year to date.
  • Donation Goals

    AVSIM's 2020 Fundraising Goal

    Donate to our annual general fundraising goal. This donation keeps our doors open and providing you service 24 x 7 x 365. Your donation here helps to pay our bandwidth costs, emergency funding, and other general costs that crop up from time to time. We reset this goal every new year for the following year's goal.


    2%
    $565.00 of $25,000.00 Donate Now
×
×
  • Create New...