Proper thrust/Vertical speed for TO

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Proper thrust/Vertical speed for TO

Postby cavity » Wed Dec 15, 2004 6:42 pm

I was wondering exactly what the climb out rate is for a 737 series airplane.  If you set the thrust at 90% after liftoff with proper flap settings, climb out at over 4000 fpm is possible if you plan on staying below 250/10000.  Reading performance charts has intial climb out numbers at 3250 fpm for the 737-400.  If I set that for the VS, I have to bring the power way back to stay below 250 .  Is this a flight modelling issue, or should I be climbing out at a higher vertical rate?  Todd
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Re: Proper thrust/Vertical speed for TO

Postby Daz » Wed Dec 15, 2004 7:24 pm

its not a modelling issue the aircrafts flying behaviour is not determined by the model its the flight dynamics that set all that....take a peak at the aircraft.cfg file for it and see if you can tinker with any settings that you know are wrong

failing that search the net for  improved flight dynamics :D
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Re: Proper thrust/Vertical speed for TO

Postby Skittles » Wed Dec 15, 2004 8:13 pm

One time while traveling, I asked the pilots what the climb rates were that they used.

They said it depends on fuel load, but for that flight, they used 2500fpm until 10,000ft then switched to 3300fpm.
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Re: Proper thrust/Vertical speed for TO

Postby beefhole » Thu Dec 16, 2004 4:45 pm

An interesting mistake even veteran simmers (like myself) make is setting power according to percent TOTAL thrust.  For example, the 90% tick mark on your joydtick.  I just figured this out when I was reading about how a jet turbine works-power settings are given in % N1, not percentage of thrust available.  The two guageson the top of the left engine gauges stack are the N1 indicators.  THAT'S what you're looking for for TO power.  In general, you are to spool the engines up to 40-50% N1 for equalization before setting TO power.  This does not mean you move your throttle to the 50 % tickmark.  You're looking for 50 to be displayed on the N1 indicator.  Then, you are to advance the throttles to 95-98% N1(in general).  This would be about the 75% tick mark on your joystick.  I just recently discovered this myself, since I too had problems keeping the aircraft under 250 kts. Using this procedure ensures that not only will you stay under 250 kts, but you will also be able to maintain V2+20, something that I had previously thought impossible!  This should help.  Also, I generally set my climbout VS to 2700 fpm and hten gradually decrease it to 2400 by 10,000 ft.  Skittles, I'm surprised the VS actually increases above 10,000 ft, but I'm guessing after increasing it they bring it down during the climb.

So, moral of this single-spaced story?  Set power using N1, not your joystick percentage markes.  That'll keep your speed down.  And lower your initial vs a bit, 24-2700 works perfectly.
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Re: Proper thrust/Vertical speed for TO

Postby cavity » Thu Dec 16, 2004 6:58 pm

I guess I left some stuff out.  I do usually set N1 for 90-93% after proper spool up.  I have a yoke so I have always used N1.  I stated modelling in my initial post, but I was suggesting flight modelling.  I often tinker with the flight dynamics sections, seems the FFX planes are extremely over powered even when fully loaded.  After so many hours in the cockpit, my interst has turned to accurate performance, and realistic fuel burn.  There are some exceptionally talented people out there who have created some great new flight dynamics, but I think the whole area needs to be addressed in the future.  Amazing how flying around looking at stuff no longer does it for me.  After purchasing 727 professional, I was hooked on the panels, start up, and fuel planning.  Still just do some fun VFR from time to time though.  Thanks for the replies.  Todd
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Re: Proper thrust/Vertical speed for TO

Postby Silver1SWA » Fri Dec 17, 2004 12:21 am

I found what you are talking about to be a real issue with the default 737 in FS2004.  I'm curious...what 737 are you flying?  It must all be in the flight dynamics.  I have found the PMDG 737NG to be much more gradual when it comes to airspeed after take-off.  In other words, your N1% stays rather high while the airspeed slowly climbs.  The default 737 would arrive at 250 kts almost immediately...very annoying.
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Re: Proper thrust/Vertical speed for TO

Postby beefhole » Fri Dec 17, 2004 2:46 pm

Hmm, I fly the default and, if the proper thrust is set, I no longer have the problem of reaching 250 kts.
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Re: Proper thrust/Vertical speed for TO

Postby cavity » Fri Dec 17, 2004 3:01 pm

Thats what I usually do, either set the VS for about 3800 or more on the autopilot to stay below 250, or climb out at a high angle if hand flying.  Silver, do you have any other payware?  How would you rate the PMDG 737?
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Re: Proper thrust/Vertical speed for TO

Postby Silver1SWA » Fri Dec 17, 2004 4:08 pm

I own the PMDG 737, Arianne 737-300 and the PSS A320.
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Re: Proper thrust/Vertical speed for TO

Postby cavity » Sat Dec 18, 2004 8:31 am

Sounds like I may need to get that.  I love 727 professional, although I do miss locking onto the route using GPS, and even the VOR/Nav lock is a bit weak.  I agree with you 100% on the default 737, cut back to 65-70% after rotation, just doesnt seem to cut it.  When I took the ATP pilot test, I climbed out at 4500 fpm because if you dont keep the engines in the proper thrust range its counted against you.  Lucky I passed that test and proudly display my certificate, somewhere under piles of other unimportant papers that is.  Todd
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