Archived

This topic is now archived and is closed to further replies.

flusie01

PMDG 737 and VSpeeds

Recommended Posts

Hello,i have a ugly Problem.Ok, i load the C172, then the PMDG 737-800.Now only the Ground Power on.Clear the Wetter.Images are here http://www.starflight-virtual.de/TopCat/image[NUMBER].jpgPlease change the NUMBER of the image without the []Now load exactly 28803,30 lbs Fuel and 32418 lbs FreightSo we have exactly 156000lbs Gross Weight. ( image33 )Now load the FMC a litle Route from EDDP to EDDF over FUL VOR.Wetter is fine in EDDP 15

Share this post


Link to post
Share on other sites
Help AVSIM continue to serve you!
Please donate today!

Hello,i have a ugly Problem.Ok, i load the C172, then the PMDG 737-800.Now only the Ground Power on.Clear the Wetter.Images are here http://www.starflight-virtual.de/TopCat/image[NUMBER].jpgPlease change the NUMBER of the image without the []Now load exactly 28803,30 lbs Fuel and 32418 lbs FreightSo we have exactly 156000lbs Gross Weight. ( image33 )Now load the FMC a litle Route from EDDP to EDDF over FUL VOR.Wetter is fine in EDDP 15

Share this post


Link to post
Share on other sites

Hello,the links are working.As i write before...replace the NUMBER with the number of the imagehttp://www.starflight-virtual.de/TopCat/image33.jpghttp://www.starflight-virtual.de/TopCat/image34.jpghttp://www.starflight-virtual.de/TopCat/image35.jpghttp://www.starflight-virtual.de/TopCat/image36.jpgAnd i have the correct Manual Pages taken for the 737-800 for the Speeds.The RWY Length is not a factor in EDDP . Not for the 736 and not for the 738 i think.Also the Wether is the same at both Situations, 736 and 738.I dont know why the VSpeeds are so VERY different in the 738 ???Also i have testet also the 739. Here the Speeds are also the same as in the Manual.That says the FS Wether Situation is the same for all Aircrafts, but the FMC of the 738calculates wrong VSpeeds.Can you thest it with your own FlightSim ?ThanksMatthias...i'm absolutely confused about that ... the 738 is the Airplane i will fly :-(

Share this post


Link to post
Share on other sites

I've found minor errors in older manuals by pmdg, if I have any doubt I always go by the FMS. Whatever Vr it provides seems to work pretty good. Jose might chime in and add more thought.

Share this post


Link to post
Share on other sites
Hello,that will mean .. "what ever the Manual says about the VSpeeds take the VSpeeds from the FMC" or ?Ps.: I have taken some Videos:http://www.starflight-virtual.de/pmdg_738/http://www.starflight-virtual.de/pmdg_736/1. Question: Can you find here any errors ?2. Question: Cany you try to reproduce the same Situation as min on your PC ?Thanks a lotMatthias
Hi Matthias,From your video i notice that you use Topcat.If you generate a Take Off and Landing report using Topcat you will find that the V speeds are printed on the report.You can then check them against the FMC on the aircraft.Most users find that the topcat figures are realistic.The NG when produced was ahead of its time however time has caught up with it and as a result some of the information in the manuals has been updated.Use the Topcat derived v speeds for accuracy.RegardsNorman Bowman

Share this post


Link to post
Share on other sites
Hi Matthias,From your video i notice that you use Topcat.If you generate a Take Off and Landing report using Topcat you will find that the V speeds are printed on the report.You can then check them against the FMC on the aircraft.Most users find that the topcat figures are realistic.The NG when produced was ahead of its time however time has caught up with it and as a result some of the information in the manuals has been updated.Use the Topcat derived v speeds for accuracy.RegardsNorman Bowman
Hello,thanks for Answering.But can you explain me why the VSpeeds calculated by the 737-800 FMC are so very different again the Manual and the VSpeeds from the 737-600 and 737-900 are exactly the same as in the Manual ? ( Tested on the Same Weather Situation in FS9 )Matthias

Share this post


Link to post
Share on other sites
Hello,thanks for Answering.But can you explain me why the VSpeeds calculated by the 737-800 FMC are so very different again the Manual and the VSpeeds from the 737-600 and 737-900 are exactly the same as in the Manual ? ( Tested on the Same Weather Situation in FS9 )Matthias
Hi Matthias,In image 33 you show the FS fuel and payload view.This should never be used for PMDG products as it distorts the performance of the aircraft.At the weights shown you are overloading the aircraft.In an earlier post I suggested that you are mixing up the weight selections.In 34 your weights are shown as LBs yet in the image showing the PMDG manual you are pointing to a weight value which is shown in 1000kg.The max weight for the 800 is just over 68000kgNorman Bowman

Share this post


Link to post
Share on other sites
Hi Matthias,In image 33 you show the FS fuel and payload view.This should never be used for PMDG products as it distorts the performance of the aircraft.At the weights shown you are overloading the aircraft.In an earlier post I suggested that you are mixing up the weight selections.In 34 your weights are shown as LBs yet in the image showing the PMDG manual you are pointing to a weight value which is shown in 1000kg.The max weight for the 800 is just over 68000kgNorman Bowman
Hello,have you shown my 2 Videos ??Here are all weight in LBS.Please...can you try to reproduce my Situation in your FS and give me an info if yourVSpeeds then are the same in your FMC and your Manual ??For that please easy clear all wether in your FS and locate your 738 in EDDP.Than load 35144 LBS of Freight and 10001.17 lbs of Fuel.Programm the FMC from EDDP to EDDF over FUL VOR and give me the VSpeeds from your FMC.Thats all what i want.I know about SOME Errors in the Pictures.ThanksMatthias

Share this post


Link to post
Share on other sites
Hello,have you shown my 2 Videos ??Here are all weight in LBS.Please...can you try to reproduce my Situation in your FS and give me an info if yourVSpeeds then are the same in your FMC and your Manual ??For that please easy clear all wether in your FS and locate your 738 in EDDP.Than load 35144 LBS of Freight and 10001.17 lbs of Fuel.Programm the FMC from EDDP to EDDF over FUL VOR and give me the VSpeeds from your FMC.Thats all what i want.I know about SOME Errors in the Pictures.ThanksMatthias
Hi Matthias,I will,in the course of Sunday ,Load as per your weights check against 1) the manual 2)against Topcat and post some feed back Late Sunday.Norman

Share this post


Link to post
Share on other sites

Not sure if this helps but I noticed in the first example you stated that you loaded 28,000lbs+ of fuel yet in 'Image 36' if you look under the speed charts at your fuel gauges it shows approximately 8600lbs.Appears that the fuel was not loaded.Just my .02Gene Levulis

Share this post


Link to post
Share on other sites
Not sure if this helps but I noticed in the first example you stated that you loaded 28,000lbs+ of fuel yet in 'Image 36' if you look under the speed charts at your fuel gauges it shows approximately 8600lbs.Appears that the fuel was not loaded.Just my .02Gene Levulis
Hi Matthias,Just tried out your figures and yes the FMC figures do not correspond with the ones written in the manual.You need to bear in mind that most virtual pilots do not use the manual for take off v speeds.Most either use the Topcat program for the vspeeds,inserting them into the FMC as per the real world,or will use the FMC generated figures.Your original question was why was the manual correct for the 600/900 and not the 800,I cannot answer as only PMDG staff may be able to help.Norman Bowman

Share this post


Link to post
Share on other sites
Hi Matthias,Just tried out your figures and yes the FMC figures do not correspond with the ones written in the manual.You need to bear in mind that most virtual pilots do not use the manual for take off v speeds.Most either use the Topcat program for the vspeeds,inserting them into the FMC as per the real world,or will use the FMC generated figures.Your original question was why was the manual correct for the 600/900 and not the 800,I cannot answer as only PMDG staff may be able to help.Norman Bowman
Hello,thanks a lot for your help !!So i am now sure thats not an error on my site.Now .. how can i connect the PMDG Staff and what Speeds are correct ?And .. how can i find out what are the correct VSpeeds ( for me ) i have to use?FMC, TopCat oder the one in the Manual ?? :( Matthias

Share this post


Link to post
Share on other sites
Hello,thanks a lot for your help !!So i am now sure thats not an error on my site.Now .. how can i connect the PMDG Staff and what Speeds are correct ?And .. how can i find out what are the correct VSpeeds ( for me ) i have to use?FMC, TopCat oder the one in the Manual ?? :( Matthias
Hi MatthiasSometimes it is a matter of what you as the pilot wishes to use.I use Topcat for all of the aircraft which it supports.With a recent flight from LFBO to EGLL the Topcat speeds and the FMC speeds came out as almost alike.(Within two or three Knots).If the speeds vary by a large margin,FMC to Topcat ,it is usually because I have not used identical parameters when loading either Topcat or the FMC.Norman Bowman

Share this post


Link to post
Share on other sites
Hi MatthiasSometimes it is a matter of what you as the pilot wishes to use.I use Topcat for all of the aircraft which it supports.With a recent flight from LFBO to EGLL the Topcat speeds and the FMC speeds came out as almost alike.(Within two or three Knots).If the speeds vary by a large margin,FMC to Topcat ,it is usually because I have not used identical parameters when loading either Topcat or the FMC.Norman Bowman
Hello again,sorry for the late answer, but i have checked "Enable email notification of replies?" , but become no eMail .. hmm.Ok, the question about the VSpeeds is also why are the Speeds in the same outside situation and the same procedure i taken to programm the FMC and load the airplane, in the 737-600 the same and in the 737-800 so very different ??Load the 737-600 and crosscheck the FMC and TopCat Speeds ---- are the sameLoad the 737-800 and crosscheck the FMC and TopCat Speeds ---- very different ( not only 1 or 2 knots )I have taken the absolutely same procedure for both airplane setups !!You can also call me via icq : 258167793ThanksMatthias

Share this post


Link to post
Share on other sites
Hello again,sorry for the late answer, but i have checked "Enable email notification of replies?" , but become no eMail .. hmm.Ok, the question about the VSpeeds is also why are the Speeds in the same outside situation and the same procedure i taken to programm the FMC and load the airplane, in the 737-600 the same and in the 737-800 so very different ??Load the 737-600 and crosscheck the FMC and TopCat Speeds ---- are the sameLoad the 737-800 and crosscheck the FMC and TopCat Speeds ---- very different ( not only 1 or 2 knots )I have taken the absolutely same procedure for both airplane setups !!You can also call me via icq : 258167793ThanksMatthias
Hi Matthias,I will be away for about six weeks so that you are going to have to try and get your answers from someone else.One final thought is that 600 series was produced in 1994 ,as is common in the real world adjustments and improvments have taken place.and rather than update the manual the PMDG team carried on producing new models etc.Norman Bowman

Share this post


Link to post
Share on other sites

Hello,i have written to the PMDG Support and hope i become a positive response.If here is another user and can help me...plese contact me.ThanksMatthias

Share this post


Link to post
Share on other sites

Ok, I tested this for all 4 versions of the 737NG30000 lbs of payload10000 lbs of fuel5

Share this post


Link to post
Share on other sites

Hello,thanks for your Help, in the FMC i have the same Values with your Payload and Fuel.But the Question was the difference between the Values from the FMC and the Manual !!Look here :LBSFMC PERF INIT PAGEPMDG ManualFMCTOPCATACPayloadFuelGrossWeightZFWV1VrV2V1VrV2V1VrV2737-6003000013300123500110,2118119129118119129Not avail in TopCat737-7002100016000120000104,1116119129116119129123124128737-8004379112000147000135,1143145154130140149140141147737-9004350012000150000138,2143145155143145155Not avail in TopCatLook at the Bold red marked Speeds !!!FMC VSpeeds from the 736, 737 and 739 are absolutely the same as in the Manual !!But the FMC VSpeeds fromn the ( mostly flown ) 738 are absolutely different and not only 1 or 2 Knots !! That was nearly 10 knots difference !!!Are that Differneces the same on your System ?Why we have differences with the 738 ??Matthias Ps.: I have added a Picture of the Excel Table .. lost the format in the Post

Share this post


Link to post
Share on other sites

Just a small piece of information, in case you are not aware of it...V1 is dependent on runway length in general, so for a given TOW and flap setting, V1 is not going to be the same for a 7000ft or 10000ft runway, given that V1 is the maximum abort takeoff speed ( I know some call it the decision speed, but that term is misleading, since the decision to abort cannot be made after it...). The less tarmac you have for your takeoff run, the slower your V1 will be... Vr and V2 are not runway dependent as far as I am aware.I believe TopCat takes runway length into account when calculating this stuff... the manuals will only give basic data on a standard runway length (maybe 10Kft?)Andrew

Share this post


Link to post
Share on other sites

Hello,yes i know, V1 is the Speed, when i slower as V1 i can STOP the Take Of run.But as your write

Vr and V2 are not runway dependent as far as I am aware.
Vr and V2 are also as V1 very different between the Values from the FMC and the Manual!!And also for a Runway length as in EDDP ( more then 11000 ft ) are the Runway length no theme for the calculated V1 !Also i have taken the ICAO Wheater ( 15

Share this post


Link to post
Share on other sites

I just use the values calculated by the FMS. I sometimes reduce V1, particularly if the runway is shorter, but I leave Vr and V2 at their respective settings. At lower temps on longer runways, I consider assumed temperatures and de-rates, but without actual guidelines, it is difficult to calculate the required assumed temps... this is where TOPCAT can come in, but I don't have that...The FMS Vr/V2 have always worked thus far.Andrew

Share this post


Link to post
Share on other sites