On speed trimming for what?

[nicesub]

Hi,

As I am trying to learn how to land the plane I keep hearing fly it on speed (yellow circle) and trim. 

My question is what do you mean trim? Trim for what? So that the plane flies level when on the yellow circle no matter what or for some specific descent rate or what? What I need to target with the trim? Confused with this as everyone keep throwing this word trim but never specify desired effect to be chased with it.

[razo+r]

In general, when someone says trim the plane, it means that you have to trim it in such a way, that there are no forces on the stick, basically the aircraft remains in a fixed attitude at a specified speed.

When someone says trim on speed, it means you have to trim it in such a way, that your aircraft maintains the perfect AoA for landing, indicated by the yellow circle.

And as it is the AoA for landing, you should be in a landing configuration. But if you do it in level flight or on the standard 3 degree glide is up to you. You just have to trim it in such a way that the aircraft maintains the on speed AoA. The trim is mostly the same, regardless if you are in a descent, level flight or climb as long as you maintain the speed. Trim changes with speed, so once you are on speed, you shouldn't have to touch trim anymore until touchdown if trimmed perfectly.

Quote

Confused with this as everyone keep throwing this word trim but never specify desired effect to be chased with it.

Trim is one of the very basics of aircraft. You can easily find hundreds of thousands of ressources online about what trim is.

Here's an example:

https://pilotinstitute.com/aircraft-trim-explained/

Edited Monday at 10:13 PM by razo+r

[nicesub]

But if I trim for the cat to fly level whilst at the yellow circle, how the hell it will descend to land if all is fixed in place?

[razo+r]

6 minutes ago, nicesub said:

But if I trim for the cat to fly level whilst at the yellow circle, how the hell it will descend to land if all is fixed in place?

You reduce power, which in turn will slow you down, less lift, nose goes down, aircraft starts to descend. If you increase power, the aircraft will start to climb.

Or you use the elevators to pitch down and reduce the power a bit so you don't pitch up again.

Edited Monday at 10:31 PM by razo+r

[RustBelt]

In landing you pitch (trim) for speed, and use power for climb descent. With a spring centered joystick trim is hard to understand. You’re using the stick to hold the nose at your desired AoA (and so speed) in a real plane or with Force Feedback, you then trim until you don’t have to hold the stick where you put it. You’re moving the neutral point of the stick.

With a spring centered joystick it becomes unintuitive, as you trim you’re bringing the stick back to its centering point to emulate trimming off forces. So the stick position changes as opposed to the stick staying where it is and force against keeping it there trims away. 

[Q3ark]

9 hours ago, nicesub said:

But if I trim for the cat to fly level whilst at the yellow circle, how the hell it will descend to land if all is fixed in place?

When you’re on finals and you’re all nicely trimmed out use power to adjust your glide slope.  

[CF104]

On 8/18/2025 at 4:24 PM, nicesub said:

But if I trim for the cat to fly level whilst at the yellow circle, how the hell it will descend to land if all is fixed in place?

Sounds like you need some instruction on aircraft dynamics during approach. 

When you are trimmed On-Speed (correct AOA) for approach in level flight, the following governs your success.

1. power controls rate of climb and descent

2. Pitch controls speed. 

3. Use DLC (Direct Lift Control) to fine tune your touchdown point in-close.

When properly flown, an approach uses power to control the rate of climb/descent. The aircraft will maintain the On-Speed AOA throughout as long as the power applications are smooth and you're NOT applying pitch inputs on the stick. Don't touch the trim at this point. If you are high, reduce power. If you are low, increase power. Also remember that if you need to increase or reduce power, do it in small amounts and be prepared to reverse the power inputs to prevent overshooting the desired result.

The use of DLC will help in making pinpoint landings. It doesn't take long to get used to it and allows you to change your rate of climb/descent momentarily without changing the power settings. 

Set up a flight and just do some slow flying to work through these techniques. Assign DLC to buttons on your control stick or throttle, or just use the keyboard (much harder). Start by trying to fly level, trimmed On-Speed (correct AOA) for approach(AOA indexer O lit up) and DLC on. Turning on DLC will give you a mild pitch down that will require nose up trim.  Now that you're stable, start reducing power in small amounts to increase rate-of-descent. Now apply some power to reduce the rate-of-descent. Once mastered you can pinpoint the rate-of-descent you desire and keep it steady there. Use DLC in small amounts to fine-tune your approach in-close. DLC switch forward increases descent and DLC switch aft decreases descent.

I highly recommend you start out by reading Chuck's Guide on the Tomcat as it provides a lot of insight into flying and operating the jet.

https://chucksguides.com/aircraft/dcs/f-14b

Regards,

John

 

 

[Czar]

On 8/18/2025 at 7:24 PM, nicesub said:

But if I trim for the cat to fly level whilst at the yellow circle, how the hell it will descend to land if all is fixed in place?

It is not trim for level flying.
It is trim for AoA (angle of attack). You can descend or ascend in landing trim all day long. What will bring you into the glideslope and keep you in it for landing is power setting or throttle.

Welcome to the forum nicesub!

Edited 1 hour ago by Czar