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Why do I just barely make it off the tarmac in time?


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Posted

I am flying PMDG 737 800/900 series. I have read through the manual a few times now but I'm not fully understanding what I'm doing wrong on this one. My home field I like to fly out of is Atlanta Hartsfield. I have been taking off from rwy 8L numerous times now in short hops over to Charlotte. Well anyway..I notice that when I get to V rotate, I barely have enough runway left to get off the ground. I am able to do it, but I notice a lot of other heavys getting off the ground sooner than I do on the same respective runway, even much larger aircraft. When I pull onto the runway, I rev N1 to 40%, let off brake, hit the TO/GA switch on the MCP and off I go. I have set the speed (from takeoff page plus 5 )in the IAS/MACH selector. Flaps are set to 5. I have tried only using the max for N1 (24K) and CLB from the N1 limit page on FMC thinking this would give me max performance. Any thoughts as to what I am missing here?Thanks,Chris Williams

Posted

Chris,In addition to what Ryan said about your fuel and payload (make sure you set-add your fuel and payload in the 737 fuel planner util--I think found on PMDG's downloads page)...You need to also make sure you have hit all your PERF pages in the CDU/FMC so that it updates your correct gross weight.It sounds like to me you have probably missed those pages even though you set your Vr speeds.Good luck!

Jeff D. Nielsen (KMCI)

https://www.twitch.tv/pilotskcx

https://discord.io/MaxDutyDay

10th Gen Intel Core i9 10900KF (10-Core, 20MB Cache, 3.7GHz to 5.3GHz w/Thermal Velocity Boost) | NVIDIA GeForce RTX 3090 24GB GDDR6X | 128GB Dual Channel DDR4 XMP at 3200MHz | 2TB M.2 PCIe SSD (Boot) + 2TB 7200RPM SATA 6Gb/s (Storage) | Lunar Light chassis with High-Performance CPU/GPU Liquid Cooling and 1000W Power Supply

Posted

If the problem is the nose is stuck to the ground, it doesn't rotate at Vr, then check your trim. Too much nose down trim turns this baby into a big expensive bus.

Dan Downs KCRP

Posted

I used the "aircraft load manager" that is under PMDG and set the 800 single to: forward 4574, aft 5656; Pax weight: 31500, cargo 10230, zfw 133030, max takeoff weight 173k, max zfw 136000, max fuel load 39970.I must say that I have not revisited this load manager since my maiden voyage when I got the software, so it was only set for the 800 single, not the 800 mixed or 900 single/mixed. I'm wondering now if that may have had something to do with it since I mainly fly the 900 series. I have attempted a different flap setting once (10) which really did not seem to make any difference. I'm now starting to question if it has been a situation with the fuel weight.Chris

Posted

Hi,Max Zero Fuel Weight for 737-800 is roughly 61,6 Tons. Normally 60 Tons is realistic (fully loaded)Don't try to use more flaps, it will increase drag.You said that your engines are limited to 24k. I don't use reduced thrust for t/o at that weight. 26k is needed.What are your V-Speeds? It's a good indication of your weight.To what value do you trim?Another thing you could do (short RWY). Brake manually, set thrust to 70% and once the engines almost spooled up to 70%, release brakes and apply full thrust.

Posted

Just for the record the only "normal" flap setting for takeoff (at least in the 800) are 1, 5 and 15. The only places I have ever used 15 is when we were heavy and flying out of LGA, DCA, or SNA.

Tom Landry

 

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