Matching Level-flying Autopilot with trim

[PREC0GNITIVE]

Hey Guys

 

I am pretty new to IL-2 but loving it so far. Just wanting to get some advice from you veterans out there regarding trim.

 

I have my pitch, yaw, roll trims set to my joystick and I get the concept of what they do and use them somewhat often however:

 

I notice if the level-flight auto pilot is on it is rock solid and flies on an hard straight line.

Is this achievable with good trim? Or is the autopilot just making minute adjustments as it goes?

When I adjust the trim so I can let go of the stick I seem to having to be constantly adjusting the trim...

 

Additionally is there a way to tell optimum prop RPMs etc? I max everything for take-off and generally leave it at 100 (except the throttle/ mixture)

 

I am mainly flying the Pe-2 Series of planes as a reference.

 

Cheers

 

Prec0g

[FTC_DerSheriff]

The auto pilot is basically flying with the optimal trim all the time. 

Theoretically achievable. But a lot of work and therefore useless since it negates the benefit of trim 

Edited April 1, 2018 by DerSheriff

[Lemon]

hi Precognitive, welcome to the sim,

by the way you had an answer from DerSheriff, he s a top pilot and a star lol , and i encourage you too click on his link on his signature many good quality ,guides and tips from him.

thank you much by the way Mr. DerSheriff for all the time you spend to help and entertain other people in your videos, you made me better in many aspect of the sim

[TP_Jacko]

For a given constant speed you can set trim and fly hands free for some time. Any change in speed will need to change the trim. You can also set the trim to hold the nose up to climb at a constant speed. 

 

Have a look at Col Ninny's video on trim.

forum.il2sturmovik.com/topic/34421-col-ninnys-how-to-fly-tutorials-for-new-and-advanced-players/

Lesson 3 

Edited March 29, 2018 by TP_Jacko

[Pict]

On 3/24/2018 at 3:35 AM, PREC0GNITIVE said:

I notice if the level-flight auto pilot is on it is rock solid and flies on an hard straight line.

Is this achievable with good trim? Or is the autopilot just making minute adjustments as it goes?

 

Yes & yes

 

1. Once you have set your engines up for optimum cruise.

 

2. Set your pitch trim, while watching the Vertical Speed Indicator (VSI), this will always just be an initial setting that you will change after the following steps.

 

3. Set your rudder trim. To do this you need to look at your turn & bank indicator which is between the Vertical Speed Indicator (VSI) & Altimeter. Look at the ball and if the ball is to the right, add right rudder trim, if the ball is on the left add left rudder trim, until you have the ball spot on in the center.

N.B. Correct rudder trim is important to counter engine torque and get you flying straight along your center-line, and has a large affect on your speed.

 

4. Set your roll trim until the aircraft is level in the horizontal as seen on the Artificial horizon gauge.

 

5. Let the aircraft settle for a bit and watch the clocks, as it speeds up, the airflow over the wings (aerofoils) will create lift and as it climbs it will lose speed and therefore lift and start to dive, once again speeding up and eventually climbing.

It takes a little time and fine tuning to reduce and finally eradicate this porpoising cycle and you may settle for a gentle rise & fall of the Vertical Speed Indicator (VSI).

 

6. Repeat steps 1 - 5 until happy  

 

Tip:- Rather than just winding on trim, try to hold the joystick where the aircraft is level and wind the trim on then, reducing the pressure on the stick at the same time, effectively winding the tension out of the stick. If you can master this, it is the quick way to trim out the aircraft. 

 

 

On 3/24/2018 at 3:35 AM, PREC0GNITIVE said:

Additionally is there a way to tell optimum prop RPMs etc?

 

Best way to set the engine is with the gauges within the cockpit as the HUD "technochat" feature that reads off in % just indicates the position of your control lever. It does not take into account any balancing that is required to achieve optimum settings for the engine, nor does it take into account changes in manifold pressure that happen when you change altitude or supercharger gears.

 

Best settings can be found in the map or in any of the many tutorials available on this site. Like the most excellent video tutorials by SYN_Requiem https://www.youtube.com/c/TheAirCombatTutorialLibrary?gvnc=1 I recommend taking the time to watch as many as possible, but with regards to your question of particular interest to you would be the following;

 

Pe-2 Series 35 https://www.youtube.com/watch?v=DDA5yJyUNoU&list=PLnyigzFtHeNoZw4NdT4jjwY5rFET4_cBf&index=4&t=0s

Pe-2 Series 87 & 110 https://www.youtube.com/watch?v=2DKdLqGXfUs&t=0s&index=9&list=PLnyigzFtHeNquPvKFr3mazkk_VK0JpxUw

Multi engine #1 - Principles https://www.youtube.com/watch?v=TNHZZP8NUgQ&t=0s&list=PLnyigzFtHeNqmQMVhq1Shl972CPX4O-0B&index=13

Multi engine #2 - Handling engine failures https://www.youtube.com/watch?v=i9roIW1OuXM&index=14&list=PLnyigzFtHeNqmQMVhq1Shl972CPX4O-0B 

Edited March 31, 2018 by Pict

[Warpig]

Trim is an interesting thing. I can never get it perfect to where I can just fly hands-free , if even for just a few moments at a constant speed. But.. If you train yourself to always be adjusting pitch trim, to adjust your attitude--it pays off in a big way and will save you a lot of work on the joystick.

 

Yaw and roll trims are a big help too, but pitch trim is the most important of them all. Start using it from day one, and you'll be a much better pilot for it

 

For RPM's, use performance charts to see the ideal RPM ranges for cruise, combat, etc. Once you know to use your gauges, engine management becomes simple. You use your tachometer to adjust RPM bands, and use your manifold pressure to adjust your throttle. Use your temperature gauges to adjust radiators and cowls. Mixtures can be a bit more tricky depending on the plane, but usually you would use an auto-lean for cruise, and auto-rich for combat. You'll learn more about that with time and experience.

Edited April 2, 2018 by Warpig

[AndyJWest]

It is unrealistic to expect to be able to set BoX trim for 'hands free unlimited flight'. The real aircraft being modelled (without autopilot) can't do that. The purpose of trim is to minimise control inputs, and reduce control forces, rather than to eliminate them entirely. Even when ideally trimmed you still need to make small inputs. 

[Pict]

2 hours ago, AndyJWest said:

It is unrealistic to expect to be able to set BoX trim for 'hands free unlimited flight'.

 

That's only true because BoX doesn't have unlimited maps and when you get to the edge the game takes over and turns your plane around  Anyhow up until you nobody was talking about unlimited hands free flying...

 

You can trim a plane out in BoX or the real thing to fly hands off for the distances we fly in BoX with ease.

Edited April 2, 2018 by Pict

[AndyJWest]

27 minutes ago, Pict said:

 

That's only true because BoX doesn't have unlimited maps and when you get to the edge the game takes over and turns your plane around  Anyhow up until you nobody was talking about unlimited hands free flying...

 

You can trim a plane out in BoX or the real thing to fly hands off for the distances we fly in BoX with ease.

Would you care to back that up with some actual evidence regarding (a) BoX, and (b), the real thing?

[Warpig]

3 hours ago, AndyJWest said:

It is unrealistic to expect to be able to set BoX trim for 'hands free unlimited flight'. The real aircraft being modelled (without autopilot) can't do that. The purpose of trim is to minimise control inputs, and reduce control forces, rather than to eliminate them entirely. Even when ideally trimmed you still need to make small inputs. 

I could have worded that better. What I meant was, I cannot trim the plane to fly perfectly level even momentarily. Even adjusting pitch trim in 1% increments, the plane will either gain or lose altitude. I always wish I can find that sweet-spot when my speed isn't changing, but I'm never successful at it.

[AndyJWest]

19 minutes ago, Warpig said:

I could have worded that better. What I meant was, I cannot trim the plane to fly perfectly level even momentarily. Even adjusting pitch trim in 1% increments, the plane will either gain or lose altitude. I always wish I can find that sweet-spot when my speed isn't changing, but I'm never successful at it.

The thing is, pitch trim isn't really an 'altitude' control. At best it controls the angle of attack, and indirectly, the airspeed. You are never going to be able to set up trim to hold an exact altitude, since any deviation from either the ideal pitch setting or throttle setting is going to result in a climb or descent. And even when you get it as close as you can, the dynamic aspects of stability will probably result in 'phugoid' long-period variations in altitude: 

https://en.wikipedia.org/wiki/Phugoid

 

Aircraft stability is a complex subject, and I don't pretend to understand it all. What I do know however is that a great deal of effort went into developing autopilots, for both military and civilian aircraft, because the designers knew that trying to achieve 'perfect trim' was impossible. You need gyroscopes and positive feedback mechanisms for that.

 

Edited April 2, 2018 by AndyJWest

[Pict]

On 3/30/2018 at 8:16 PM, Pict said:

5. Let the aircraft settle for a bit and watch the clocks, as it speeds up, the airflow over the wings (aerofoils) will create lift and as it climbs it will lose speed and therefore lift and start to dive, once again speeding up and eventually climbing.

It takes a little time and fine tuning to reduce and finally eradicate this porpoising cycle and you may settle for a gentle rise & fall of the Vertical Speed Indicator (VSI).

 

I never use or look for the fake autopilot stability when I fly in BoX...

 

Like I said, manual trim is good enough for the flying done in Box, at least the flying I do, and that includes bombers doing level bombing and navigating complex routes to target with the wonder-woman compass & gps and all that stuff...

 

The guy asked if he could work his trim without the auto pilot, I gave him my way of doing that. If you just want to shut him and me down, and tell us to use the autopilot because Wikipedia says so, good luck with that  

Edited April 3, 2018 by Pict

[Requiem]

Hey Precog, I answered your PM via YouTube but just to clarify something from what I've read in this thread.

 

As far as I'm aware the "Auto Level" Autopilot will not use trim so you will never replicate being as good as the Autopilot is by using trim alone. If you watch things carefully in the cockpit you can see it's the stick and rudder that move in order to maintain altitude according to your airspeed and power settings, not trim.

[AndyJWest]

21 minutes ago, SYN_Requiem said:

Hey Precog, I answered your PM via YouTube but just to clarify something from what I've read in this thread.

 

As far as I'm aware the "Auto Level" Autopilot will not use trim so you will never replicate being as good as the Autopilot is by using trim alone. If you watch things carefully in the cockpit you can see it's the stick and rudder that move in order to maintain altitude according to your airspeed and power settings, not trim.

 

Yup. It even flies the I-16, which has no trims at all.

[mpdugas]

I recall sailing once, many years ago, on a short, fat Island Packet and marveled at how it corkscrewed its way across the water, sort-of averaging the correct heading as it moved gracelessly, tossing and flopping about hilariously.

 

If you visualize an airplane as if it were a boat traversing a shifting sea state, it becomes easier to comprehend the problem of the regularity of movement; don't liken an aircraft to a land vehicle, because it's not comparable.

 

Fly an airplane with a loose, soft grip, and you'll be fine.