Trim on take off 737
Excelsis
Guest
Hi
I read on these boards and elsewhere that you have to set the nose up 10 degrees pitch before take-off on a Boeing 737-400.
How do I know what is 10 degrees while I am waiting on the runway?
The mouseover (tool tip)on the pitch wheel in the panel doesn't give me numerical degree information (unlike some other airacrft in FS9) . The only indication are the white stripes on the side of the wheel . How far is 10 degrees pitch then?
And once I rotate on the 737 do I have to reduce throttle from full thrust? If so, by how much and what is the panel indicator for that? N1?
Any advice gratefully received
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Jamie4590
Guest
You can only pitch the nose up or down when you are either airborne or are rotating the aircraft to become airborne. You can't pitch when you are stationary. I'm not sure if 10degrees is the aircrafts Theta-2 as it seems quite low (Concorde aims for 13.5 degrees but it can be higher) but assuming it is you pitch the aircraft to 10 degrees when you reach Vr (fast enough to take-off) over a period of several seconds. I believe pitch trim is used only inflight. The trim you use on the ground to stop the aircraft pitching up prematurly is performed by your horizontal stabalizer trim.
I'm not sure what the throttle procedures are for a 737 but I would imagine the throttles stay at their forward stops for a while after take off. Reducing power immediately after take-off can (and has) led to tragic consequences.
I fly 737s in real life. If you are using the PMDG 737, open up the throttle window and set your trim in the takeoff range of 3-8 degrees (set it in the green band to the left of the speedbrake lever. If it is not set in the takeoff range, you will get the takeoff warning horn when the throttles are advanced above 60% N1). The built in 737 that came with FS9 doesn't have a way to tell what the trim is set at as far as I can tell. BTW, takeoff trim is set in the event of a loss of engine on takeoff. It should have the aircraft trimmed pretty close to V2 to V2+15 airspeed range which is you best engine out climb speed for obstacle clearance.
Excelsis
Guest
Thank you both for your replies. I was getting frustrated because I kept overspeeding in the B737 ( I have just started to fly it) but my problem was that I was pitching too low after take-off. I discovered that 20 degrees is about right and I can keep my speed is to around 160 on climb out ( still can be a bit lower tho - have to practise more!).
I don't have PMDG aircraft but I will bear your advice in mins should I invest in it in the future.
Thanks!
Hi 🙂
The following is copied from my notes for the FS9 Boeing 737.400
(you cannot get a definative read-out on your trim setting - so I hope you can interpret the following)
Heaviest 150000 lbs Flaps 5: Trim : 0.8 Bar below centre bar
Auto pilot fpm ready at 1800
Midweight 11500 lbs Flaps 5: Trim: 0.4 Bar below centre bar
AP ready at 2700
Lightest 80000 lbs Flaps 5: Trim: 0.1 Bar below centre bar
AP ready at 3600
Excelsis
Guest
lionlicker wrote:
Hi 🙂
The following is copied from my notes for the FS9 Boeing 737.400
(you cannot get a definative read-out on your trim setting - so I hope you can interpret the following)
Heaviest 150000 lbs Flaps 5: Trim : 0.8 Bar below centre bar
Auto pilot fpm ready at 1800Midweight 11500 lbs Flaps 5: Trim: 0.4 Bar below centre bar
AP ready at 2700Lightest 80000 lbs Flaps 5: Trim: 0.1 Bar below centre bar
AP ready at 3600
Thanks for this but I have no idea what it means! Although I am guessing different weights affect trim settings but what does 0.8. 0.4 and 0.1 mean? And does "Bar below centre bar" mean the little white indicator at the side of the trim wheel? Are the numbers you quote altitude? And that's when you should set AP? FPM = feet per minute?
So many questions, and sorry to be dumb but if you could explain a little more I would be very grateful.
Hi Excelsis
Right in the middle of the 737.400 default panal (2d) you will see the "PITCH TRIM" wheel (only small). You will see the little calibration "bars" just to the right of that. On start-up I have noticed the little triangle is pointing to the centre bar. Change the trim and you will notice the little triangle moving up or down the calibration "bars".
With the Auto-Pilot, normally I suppose you would set all the parameters BEFORE YOU TAKE OFF. For example you set HDG , IAS/MACH, ALTITUDE, and VERT SPEED (fpm) ready at their setting before you T.O. , then hit [Z] when your in your climb. (Turn on AT/ARM also!).
Check your Gross Weight (ALT A F), before you taxi, and do your maths so you know how to set up the plane. The fpm setting I supplied are not at maximum to allow you to perform a turn directly after T.O. Once the plane straightens out, you can up the fpms even more. This is of course a take off and climb using MILITARY POWER, --- in real life you are not allowed to deafen the residents in nearby suburbs with such a thunderous display.
Excelsis
Guest
Thank you for taking the time again to explain this! Greatly appreciated.
Just one more thing: your 0.8. 0. 4. 0.1 references? Are these decimal fractions of the wheel trim below the centre bar in which the whole trim below the centre bar is 1.0. So: 0.8 would be about three-quarters trim down (or about three bars from the centre), 0.4 would be just under a half below the centre bar ( approx. two bars) and 0.1 would just be under the centre bar (about one bar).
With other aircraft you can see exactly what the percentage trim is ( + or -) by mouseover but the 737 doesn't have this- irritatingly - but then I guess real aircraft don't tell you this either 
No, 1.0 represents only one calibration bar - so 0.8 below centre bar is not quite down to the next bar.
Just try it and you'll see. Remember, this is a trial figure based on using 5 degrees flaps on take-off.
Excelsis
Guest
lionlicker wrote:
No, 1.0 represents only one calibration bar - so 0.8 below centre bar is not quite down to the next bar.
Just try it and you'll see. Remember, this is a trial figure based on using 5 degrees flaps on take-off.
Thanks Lion. All clear now. Thank you for bearing with me!
Cheers
Your query touches on two important aspects of flying a Boeing 737-400 in FS9 (Microsoft Flight Simulator 2004), specifically related to trim setting on takeoff and throttle management. Let's address these step by step:
1. Setting 10 Degrees Pitch:
It's true that you'll want to set a 10-degree nose-up pitch before takeoff on a 737-400. The challenge here, as you've pointed out, is that the tooltip doesn't provide numerical information.
- Firstly, the white stripes on the side of the trim wheel usually correspond to a trim setting, not the actual pitch degrees.
- To find the 10-degree pitch, refer to the attitude indicator on the flight panel. This displays the aircraft's attitude relative to the horizon, where you can gauge a 10-degree nose-up pitch.
- Alternatively, you can refer to the aircraft's documentation, sometimes provided with the virtual aircraft files, which might have information on corresponding trim wheel positions for a particular pitch.
2. Throttle Reduction After Rotation:
After the rotation of the 737, managing your throttle is essential. Here's what you should know:
- You'll generally not reduce the throttle immediately after rotation; you'll keep it at full thrust to reach the climb phase.
- Once you reach a safe altitude and airspeed, you may start to reduce thrust. The N1 is indeed the panel indicator you'll refer to for this. The exact value depends on your climb profile and can vary based on your flight plan and weight. Generally, it's around 85-90% N1 for a typical climb.
Note: These instructions are specific to FS9 and the 737-400 model, but principles like watching the attitude indicator for pitch information may apply to other platforms like Microsoft Flight Simulator (2020) or X-Plane 12.
I hope this clears up your confusion. Feel free to ask if you have any further questions. Happy flying!
P.S. For in-depth insights into flying the 737, you might consider referring to the official Boeing 737 manuals or other educational materials that align with FS9.
Disclaimer: Always refer to real-world manuals, guides, and expert tutorials when attempting to replicate realistic flying procedures. This advice is tailored to flight simulation and should not be applied to real-world aviation.
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