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im a little confused.....

crosscheck9 Guest

Hi,
Recently, I posted a topic called climbs, but I'm still a little confused. With the 757/737, I find that the lowest climb rate i can go to, so that i can accelerate to the final cruise speed, is around 1000fpm, so, how am i supposed to accelerte to that speed at 2100 fpm. Do I have to alter the amount of thrust exerted at the aircraft.cfg files. Any help would be appreciated, and BTW, Thanks a lot for helping me out guys. This forum is by far the best I have seen

3 Responses

Pro Member Chief Captain
tomthetank Chief Captain

😕 Cofused 😕
After takeoff your rate of climb is at its greatest as the aircraft is flying through dense air,(you get more lift out of the wing)but the higher you climb,the air becomes less dense,(less lift)so you have to lower your rate of climb

So start of with a high climb rate(2500/2700) and lower it as you climb
Some of the real high flyers go up in steps,say climb to 27000ft level out to gain speed,then step up to 30000ft and level out again,and so on

Pro Member First Officer
leadfoot First Officer

In take-off and climb configuration I hope you have your engine N#,s set at or around 90%. That is what the TOGA sets the engines to. If you can't climb at more than 1000fpm even at min alt i.e. 15000-20000' there is something wrong with your plane or possibly even your program. That being said, I configure my climb so that when I reach cruise alt, I'm within 15-20kts of target cruise speed. If my cruise alt is in the low 30s --- 31-33 thousand ft. I can still climb 1500-1800 fpm. If crs alt is 37-39 thousand ft. my climb is 800-1000fpm. How I perform my departure is as follows; I let the TOGA do the take-off roll and climb out, I set up a 10-12 degree climb angle pull up the gear and then start retracting flaps at 1000'agl, one notch at a time now, this happens around 180 kts. At 4000' agl and 235kts the last flap setting is retracted. Now I set up for a 250kts climb profile, and engage the A/P. at this time my climb is 3500fpm. Depending on weather I may have to go to 4000fpm to maintain FAA 250 kt limit under 10000'. After crossing the limit alt I nose down for a 3000fpm climb to set up cruise climb, usually around 280-290 kts. by the mid teens best climb is around 3000', by the low 20s it is down to 2500', the high 20s 2000' all the while I'm still at 280-290 kts ias. I reduce my climb a little at a time to maintain constant ias. At 2000' from cruise alt I set up the auto throttle to 290-310 ias for cruise and start slowly reduceing climb to 500 fpm and then 100' short of alt I set it to 100fpm. and engage the A/T. Upon reaching cruise alt I adjust the A/T as needed for proper cruise. If you have maintained 280-290 kts ias through-out the climb, your true airspeed at cruise alt intercept will be close to 440 kts tas. That's only 20kts short of target cruise speed. I let the A/P and A/T do the rest. Concerning the config files, I would'nt tinker with the 737s thrust at all. It is well powered for it's size. The 777 however is in my opinion somewhat underpowered. I increased the output from 84000 lbs to 95000 lbs thrust. that seemed to solve the problem. Out of the box the 777s engine N#s had to be set at 90% just to be able to cruise at book figures, and then it was still sruggling at that. I am not one to be patient with under powered planes or anything else for that matter. I hope this helps answer your questions.

Pro Member Chief Captain
Alex (Fire_Emblem_Master) Chief Captain

What you are experiencing is completely normal, so i would like to introduce you to our friends: "Cruise Climb" and "Economy Climb"

Cruise Climb: Simply put, when you take off, FPM below 10,000 should be 2200. Above 10,000 to 16,000 climb at 1700. Cruise Climb to whatever FL is approx. 15-1600FPM. You are not going to want to truly accelerate untill you level off at your cruise alitude, you'll burn way the heck too much fuel doing that, instead, climb out at 265KIAS, if the engines are struggling with that, go for 250. At high altitudes, that translates into almost .62 Mach. When you level off, the aircraft will accelerate to your set speed because of the higher N1 required to mantain a set speed during climb. You'll also notice the higher you go, the lower fuel burn becomes...to a point, of course, then it goes back up again. You may have to ajust these FPM Numbers if you're fully loaded for a trans-continental flight, but I fould the fully fueled and loaded 767-200 to Cruise Climb at 1600FPM.

Economy Climb: Essentially, you are cruse climbing at 250KIAS, with a FPM rate of 11-1300 to cruise, to save on gas.

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