Take Off Roll Problem

[Popcorn 18]

While this may very well be a user error issue, I cannot figure out what I am doing wrong. I have loaded an A320 with 100 pax and 6000kg of cargo. Set my trip distance to 900 nm and flight level of FL320. This results in a ZFW of 55,644kg and my block fuel is 11,379kg which is well within limits and doesn't appear to be a heavy load. When departing rwy 09L at KPHL, I almost use the entire rwy length before I reach my Vr speed of 158 (I think). Again, I could be wrong, but I don't think I should have that long of a take off roll. I put the throttle into the flex detent and I have also tried it in the TOGA detent, but there wasn't much improvement. It seems as though the acceleration of the aircraft is too slow. I am able to get Concorde X in the air before I can get Airbus X Extended in the air in the same situation. So my question is am I doing something wrong, or is this an issue with the add on that will hopefully be addressed? I love this add on and this is my only issue with it. Thanks for the help in advance.

Chad

[Fab10 34]

I have raised this question before, as have others.

The v-speed tables are incorrect, and an update or correction was promised.

Someone mentioned an accurate Airbus take-off performance calculator called TPC.EXE, which I found and downloaded, and this, depending on several factors and conditions, generally provides improved and/or more accurate v-speeds.

Hope this helps.

Fabio

[Airbus339 129]

I have raised this question before, as have others.

The v-speed tables are incorrect, and an update or correction was promised.

Someone mentioned an accurate Airbus take-off performance calculator called TPC.EXE, which I found and downloaded, and this, depending on several factors and conditions, generally provides improved and/or more accurate v-speeds.

Hope this helps.

Fabio

Agree. I may add that, after a bunch of flights, AXE speeds are more correct if runway's very long, while they are totally irrealistic if the runway's very short

[KAPTEJNLN 237]

well i have to agree about the takeoff roll.. I actualy did 1 test a while back and found it was unrealistic i compaired to data i got from real pilots and departing from the same runway every week but seems nearly imposible in the sim.. i got data for a flight from EKAH to GCTS and it has more waight then posible in the sim as it has the extra fuel tanks you can upgrade to in order to be able to fly that route and have enough extra fuel... i had to edit els where to get the same weight for take off and whit toga i lifted off at the end of the runway whit out safety meters left thats not right

[Fab10 34]

Another thread explored the solution of updating the thrust_scalar in the aircraft.cfg file.
This provided immediate results, and for all phases of flight (I recall that between 1.1-1.3 was added to the number depending on aircraft model).
I tried this for a while, until an Aerosoft update rewrote the cfg files, and I never bothered to reconfigure the thrust_scalar.

EDIT: 0.1 - 0.3 I think!

[Like Me 0]

Bitte Helft mir ich habe mir das Add-on auch geholt und mache alles richtig Checkliste abarbeiten und dann starte ich die Triebwerke gut bis Hier hin alles perfekt geklappt...aber dann versuche ich bei meinem Joystick immer mit dem gas hebel schub zu erzeugen aber es rührt sich nix ....selst wen ich vollstoff gebe triebwerke immer noch im leerlauf bitte helft mir ....

[KyleD 1027]

Bitte Helft mir ich habe mir das Add-on auch geholt und mache alles richtig Checkliste abarbeiten und dann starte ich die Triebwerke gut bis Hier hin alles perfekt geklappt...aber dann versuche ich bei meinem Joystick immer mit dem gas hebel schub zu erzeugen aber es rührt sich nix ....selst wen ich vollstoff gebe triebwerke immer noch im leerlauf bitte helft mir ....

Hallo,

Benutzen sie bitte die deutschen foren hier fur unterstutzung: http://forum.aerosoft.com/index.php?/forum/543-airbus-x-extended/

[--- 170]

Another thread explored the solution of updating the thrust_scalar in the aircraft.cfg file.

This provided immediate results,

Take off performance is already correct, it's just the computed speeds that are presently wrong. Changing the thrust scalar ruins the realistic performance. Hence the 'immediate results' are not the correct results.

[Popcorn 18]

Take off performance is already correct, it's just the computed speeds that are presently wrong. Changing the thrust scalar ruins the realistic performance. Hence the 'immediate results' are not the correct results.

While the v speeds are indeed high (more along a 777) and correcting them would help, I still think the thrust is off because the aircraft seems to accelerate too slowly. Comparing the trust to that of the NGX it takes much longer for the AXE to get up to speed. I know they are different planes and have different engines, but the lbs of thrust the Boeing and Airbus engines produce for those size aircraft is quite similar thus the acceleration should be similar as well.

[Cheyenne Chief Pilot 829]

It's not a bug - it's a feature: That acceleration is characteristic of Airbus.

[--- 170]

It's not a bug - it's a feature: That acceleration is characteristic of Airbus.

??? Why should an A320 accelerate any different from a B737 if they are at the same weight and use the same amount of thrust?

Nevertheless it's not possible to compare these two as the thrust reduction calculation (and engine) is different in the A320 and the B737 and hence you don't have any precise comparison about the actual amount of thrust used.

[gandy 25]

Dont really have an issue getting the A320 in the air at KPHL 9L with a heavier aircraft, in the air around taxiway L, just past M on the airport chart when rotating.

Taken from the A320 Instructor Support manual ( dated 2001 ).

"The recommended flap configuration to provide best tail clearance at take off is CONF 2. It is therefore to be used whenever performance allows, considering furthermore that when CONF 1 + F is chosen, take off close to V2 mini may have to be achieved."

Also In the Manual.. after a long winded thing about correct usage of the thrust levels..

"Rolling take off is recomended whenever possible"

I have found the a320 does struggle when using CONF+1 ( got to hit close to V2 which means a lot more runway ) and its a little heavy but CONF 2 or CONF 3 is the winner for me and gets me up in the air a lot quicker. Sadly though correct aircraft takeoff config is one of my downfalls.. regardless if im flying a little GA aircraft or something bigger but im learning.

[--- 170]

IRL we use conf 1+F for various reasons as much as possible and if the runway is long enough the speeds for conf 1+F, 2 and 3 are almost identical.

I think the conf 1+F 'struggle' will end with the new FDE that comes with SP1

[gandy 25]

When simming from my local airport it does take a little longer than i would expect when irl they get a 747SP off the runway quicker ( 2271m runway or 7450ft if you prefer )

Looking forward to sp1

[Emi 5161]

??? Why should an A320 accelerate any different from a B737 if they are at the same weight and use the same amount of thrust?

Nevertheless it's not possible to compare these two as the thrust reduction calculation (and engine) is different in the A320 and the B737 and hence you don't have any precise comparison about the actual amount of thrust used.

That one is simple. As you know from your real world experience the A320s takeoff N1 is usually not above 90%. In the 737 though higher settings than that are quite common.

Actually if you really reduce it to the same N1 level there will of cause not be a big difference.

What I have to add to this situation is the following: The Flex Temp calculated by the computer is most of the time not correct in 1.04. If you use the TPC tool mentioned above you'll get a much better one togeather with the correct speeds and then it'll work without problems

[Popcorn 18]

Again I understand the v speeds are too high, but even if they were lower, (say around 135 ± for Vr) it still takes took long for the AXE to reach that speed. My calculated Vr for the flight was 158 as I tried it again this morning and I even set TOGA and by the time I lifted off, I was just about at the intersection for rwy 35. In real life, I am a pilot (Private, Instrument, Multi) and I have been to KPHL many times and while on a taxiway have seen A320/A321's depart and they are up in the air well before the sim is. I do believe the thrust scalar is off, but I'd really like a dev team person to answer that. If I can get wheels up in the PMDG 747 with more PAX, fuel, and cargo loaded before I can get wheels up on the AXE, then something is most certainly wrong. Hope V1.10 will solve this issue, if not, I do hope a hotfix will come out soon after. This is the only issue I have with the plane, everything else is great IMO and is surely one of the best purchases I made for FSX.

[--- 170]

If I can get wheels up in the PMDG 747 with more PAX, fuel, and cargo loaded before I can get wheels up on the AXE, then something is most certainly wrong.

Why ?

747-400 400000lbs DOW + 33000lbs pax + 22000lbs fuel = 455000lbs TOW / 228000lbs thrust = 1.99

A320-200 92000lbs DOW + 33000lbs pax + 22000lbs fuel = 147000lbs TOW / 50000lbs thrust = 2.94

I really don't understand these apples and oranges comparisons

[Popcorn 18]

Why ?

747-400 400000lbs DOW + 33000lbs pax + 22000lbs fuel = 455000lbs TOW / 228000lbs thrust = 1.99

A320-200 92000lbs DOW + 33000lbs pax + 22000lbs fuel = 147000lbs TOW / 50000lbs thrust = 2.94

I really don't understand these apples and oranges comparisons

It's all logic and nothing more. Yes comparing different sims, but the 747 is obviously much larger/heavier and while it has two more engines, it should roll down the runway longer before wheels up. If you still don't understand, then perhaps look up take off distances required for a 747 under different atmospheric conditions and then the same for an A320. You'll clearly see the 747 needs more runway than the A320. however in the sim it is opposite, I can take the 747 under the same conditions and be wheels up before the AXE. Logic should say there is something wrong there.

I am not here to argue and if you feel the sim is right than that's great, but I personally (and apparently others) find it to be unrealistic to use up the amount of runway we have to before wheels up even if we calculate our own vspeeds using programs like topcat. It makes it better, but I'm still down the runway farther than needed and I believe that is because the acceleration is off a little bit.

[Joshua Che. 1601]

It's all logic and nothing more. Yes comparing different sims, but the 747 is obviously much larger/heavier and while it has two more engines, it should roll down the runway longer before wheels up. If you still don't understand, then perhaps look up take off distances required for a 747 under different atmospheric conditions and then the same for an A320. You'll clearly see the 747 needs more runway than the A320. however in the sim it is opposite, I can take the 747 under the same conditions and be wheels up before the AXE. Logic should say there is something wrong there.

I am not here to argue and if you feel the sim is right than that's great, but I personally (and apparently others) find it to be unrealistic to use up the amount of runway we have to before wheels up even if we calculate our own vspeeds using programs like topcat. It makes it better, but I'm still down the runway farther than needed and I believe that is because the acceleration is off a little bit.

No offense, but we have been at this discussion over and over again.

Pardon me for not trusting you (or anyone here) claiming the TO performance is wrong without any charts etc..... You cant expect me just to believe a stranger telling me its wrong when my RW bus pilots say its fine.....

Yes, vspeeds is a problem though, plan to be addressed after SP1.

[mrhoward 8]

No offense, but we have been at this discussion over and over again.

Pardon me for not trusting you (or anyone here) claiming the TO performance is wrong without any charts etc..... You cant expect me just to believe a stranger telling me its wrong when my RW bus pilots say its fine.....

Yes, vspeeds is a problem though, plan to be addressed after SP1.

Amen, Joshua!

It's all logic and nothing more. Yes comparing different sims, but the 747 is obviously much larger/heavier and while it has two more engines, it should roll down the runway longer before wheels up. If you still don't understand, then perhaps look up take off distances required for a 747 under different atmospheric conditions and then the same for an A320. You'll clearly see the 747 needs more runway than the A320. however in the sim it is opposite, I can take the 747 under the same conditions and be wheels up before the AXE. Logic should say there is something wrong there.

I am not here to argue and if you feel the sim is right than that's great, but I personally (and apparently others) find it to be unrealistic to use up the amount of runway we have to before wheels up even if we calculate our own vspeeds using programs like topcat. It makes it better, but I'm still down the runway farther than needed and I believe that is because the acceleration is off a little bit.

Your logic is flawed.

Just because one uses a little objective comparison, does not make it a logical argument.

There are many differing factors between a 747 and a A320. First of all, and glaringly, is THRUST to WEIGHT ratio. It's not all about EPR rating. It's also about the fact that that 1.99 EPR rating on a 747 produces a hell of a lot more thrust overall than the same amount on a 320. Not to mention that you also failed to account for the thrust REDUCTION in the scenario as well. Research and compare the differences between TO, TO1, and TO2, and how they compare to the A320 FLEX TEMP thrust reduction and then ensure you're comparing takeoff runs while using the same amount of thrust reduction. Because saying you can get the 747 in the air faster than the 320 when you're using TO is just an insult to logic.

Also, not considered or accounted for in your realism debate is flap settings. You do the SAME scenario with Flaps 1 on a 747 and tell me how much runway it takes you then. The 320 wouldn't need as much time with a Flap 3 takeoff either.

In any case, if you don't like it, design your own, ultra realistic logically flawless sim.

We'll be waiting.

[--- 170]

1.First of all, and glaringly, is THRUST to WEIGHT ratio. It's not all about EPR rating.

2. It's also about the fact that that 1.99 EPR rating on a 747 produces a hell of a lot more thrust overall than the same amount on a 320

3.Because saying you can get the 747 in the air faster than the 320 when you're using TO is just an insult to logic.

4.Also, not considered or accounted for in your realism debate is flap settings. You do the SAME scenario with Flaps 1 on a 747 and tell me how much runway it takes you then.

1. Did you really read my post? The 747s thrust to weight ratio is much higher than the A320s

2. I do hope that a 57000lbs thrust engine produces more thrust than a 50000lbs thrust engine. But a 'hell more' that surely isn't.

3. Well, I've seen a 747SP becoming airborne after a 1300ft take off run, but never an A320.

4. Flaps 1 as a take off flap setting for a 747-400???

[Cheyenne Chief Pilot 829]

(...)

Also, not considered or accounted for in your realism debate is flap settings. You do the SAME scenario with Flaps 1 on a 747 and tell me how much runway it takes you then. The 320 wouldn't need as much time with a Flap 3 takeoff either.

(...)

LOL: Now we're even comparing degrees of flaps (Boeing) to configs (Airbus).

Time to grab my ... popcorn!

[mrhoward 8]

1. Did you really read my post? The 747s thrust to weight ratio is much higher than the A320s

2. I do hope that a 57000lbs thrust engine produces more thrust than a 50000lbs thrust engine. But a 'hell more' that surely isn't.

3. Well, I've seen a 747SP becoming airborne after a 1300ft take off run, but never an A320.

4. Flaps 1 as a take off flap setting for a 747-400???

1.) Yes, I did. Which is exactly what I said. Higher thrust to weight ratio means an aircraft has a shorter takeoff roll... not a longer one. So again, it's not shocking that a lightly loaded 747 can lift off faster than an A320. It has more power to spare to accelerate faster and get airborne quicker.

2.) What A320 has a 50000lbs thrust engine? Try 25000-27000lbs at the highest rating for the IAEV2500s. So that's 27,000 x 2 engines = 54,000lbs total thrust for the A320 compared with 59,500 x 4 engines (that's the lowest rated power option on the 747) = 238,000lbs total thrust for a 747-400 Rolls-Royce. I don't know about you, but I consider 230,000lbs a hell of lot more than 54,000lbs.

3.) Again, a lightly loaded 747SP would have an insanely short takeoff run due to the fact that that 200,000lbs of thrust is designed to get 700,000lbs+ airborne. When it's not that loaded the thrust to weight performance provides even greater performance. Ever notice how much faster you walk when you aren't carrying 100lbs of weight? If not, try seeing how fast you go and how much energy you expend carrying and not carrying a large load and then you'll understand the effect lower weights effect performance with the same power output.

4.) Well you seem to want to skip the effect that flaps have on lowering the takeoff roll of aircraft. The A320 doesn't take off with the equivalent of Flaps 20 like the 747 does. It uses it's first detent. Probably closer to flaps 5 than flaps 1 on a 747, but the point remains.

You also skipped over entirely the concept of lowered takeoff engine power. So go take a 747, load it up to 75% of it's DESIGN CAPACITY (not the exact pound for pound weight you use on the a320), and perform a Flaps 5, TO2 takeoff. I don't think you'll get the same stellar performance.

And what side of this are you supporting here? I can't tell. Its seemed that you were supporting the concept that the 320 takeoff roll is accurate but then you seem to pick apart my attempt to support it as well. A bit confusing.

[mrhoward 8]

LOL: Now we're even comparing degrees of flaps (Boeing) to configs (Airbus).

Time to grab my ... popcorn!

They're all degrees Olli. How they're set may differ, but they still come down in degrees.

[Cheyenne Chief Pilot 829]

They're all degrees Olli. How they're set may differ, but they still come down in degrees.

So the Airbus CONFIG 3 has to be converted into degrees of flaps in order to compare it to degrees of flaps of a Boeing (still size and shape of different wings isn't even considered).

(...)

Also, not considered or accounted for in your realism debate is flap settings. You do the SAME scenario with Flaps 1 on a 747 and tell me how much runway it takes you then. The 320 wouldn't need as much time with a Flap 3 takeoff either.

(...)

CONFIG 3 in an Airbus is ...

20° flaps angle

and

22° slats angle

compared to flaps 1 of a Boeing 747?!?

And there's even more to say about the aerodynamics of those aerofoils when comparing one to another ...

EDIT: spelling of 'slats' corrected ...