Takeoff speeds

[musiol1 10]

Hello. I check the forum but couldn't find any topic about t/o speeds so i start new one. I don't know that this is problem or this is as supposed to be. Explenations. I fly from lgkr (Corfu) to lhbp my FOB was 6.9 and t/o speed was 142. After landing in Dudapest i start new flight (without closing sim) from Dudapest to Malaga. FOB was 10.9 and t/o was 133 (it's strange because speed was lower then last flight when i have less fuel). Before each flight i load fuel from Aerosoft.AirbusX.FuelPlanner. Will be greatfull for any answer. Greetings

[Emi 5161]

HI Lukasz,

there are many many many factors contributing to the speeds.

First and foremost: What's your takeoffweight and flap setting?
If you carry less passengers, but more fuel, or simply use another flapsetting, the resulting speeds may be the same...

Next which speed to you refer to? V1, Vr, V2, etc?

And finally the speeds are dependant on

Wind

Temprature

QNH

Runway lenght

Airport elevation

Runway condition (dry, wet, snow, slush, etc.)

Runway slope

Packs ON/OFF

Anti Ice ON/OFF

[musiol1 10]

Ok so im starting with the answer .

1. In first flight t/o weight was 63t in the second 67,1t , Flaps at position 1 in both flights.

2. I never changing passenger and cargo so it's alwats 150 pax and 3,5t cargo

3. I refrer to aech speed V1,Vr,V2 because all was lower in second flight (each speed wa about 8 or 9 knots less)

4. Weather: I'm using OPUSFSI - surface wind 020/1 for t/o from LGKR and 035/4 for takeoff to from LHBP

5. Runway for t/o at LGKR 17 (alev 6ft - dry) for t/o from LHBP 31L (elev 495ft - snow)

6. Packs off, anti ice in both cases off for t/o.

Edit

I did the same flight (LHBP-LEMG) with the same weather condition again, but firstly i resterded FSX.

Vref speeds was about 147 as supposed to be, but again after landing i want to do next flight without closing sim and speed was lowered again to Vref below 130kt with FOB 8,9.

This is really strange for me.

[musiol1 10]

Hello. Again i have same problem. 2 routes without closing FSX - LHBP-LGIR and LGIR-LHBP.

1) T/O from LHBP V1=142 Vr=149 V2=150 after landing in Heraklion i load fuel again so FOB was same 8,5 i both takeoffs

2) T/O from LGIR V1=118 Vr=129 V2=130. Climb rate almost +1000vs higher then in a first flight.

3) After landing at LHBP i do short and simply test. I load at LGIR with same weather condition and same loadshet but firstly i restart FSX. And speeds look like V1=141 Vr=148 V2=149.

How there is so big differences in t/o speeds when i dont close sim befere next flight and restart sim before next fligt. It's almost 20knot.

Will be greatfull for some test and investigation about that.

Lukasz

[FraPre 89]

Hello,

after landing you load the loadsheet data complete new or only the fuel?

From airport to airport must changing the takeoff speed. She´s dependant from many datas (see answer from Emi)

Frank

[musiol1 10]

Yes full loadshet. Look at post above you . I test ad fly from LHBP to LGIR, then without closing sim back from LGIR to LHBP (in this case V1=118 Vr=129 V2=130 at LGIR). After landing i restart sim and for sure was do again LGIR-LHBP (same Loadshet, same weather). Speeds looks like V1=141 Vr=148 V2=149. 19Kt differcences ?? it's not normal.

Now i'm pretty sure that each time if i dont close sim and want to do second fligt speeds are calculated incorectly.

I can give speeds from another yesterday flight LHBP-LICC and LICC-LHBP. Same problem lowerde speeds bofefore second t/o without closing sim.