Question to real world pilots about flight controls

[ahuimanu 50]

Because I'm not a real pilot, I'd love to ask.... if you're making a typical turn in the traffic pattern (90 degrees ~ 30 seconds), do you trim out the elevator forces during the turn or just hold the yoke back?

Basically, trim can be used at any time to relieve the forces required to hold a desired nose attitde. Since power, wind and descent/climb all influence the desired nose attitude, a pilot can be trimming quite often. If you are practicing things like steep turns and the like, you wouldn't usually be constantly trimming in an aircraft like a C172. Usually, you trim for straight and level flight, but you could also trim when a stable descent or climb is desired. However, like I said originally, you trim to make the pressure in the yoke go away when trying to maintain a desired nose attitude.

[jon b 2,050]

The biggest movement of the yoke in pitch on the 74 is on rotation after that when trimmed out only very little movement of the yoke is required to change the pitch,especially at higher altitudes.Interestingly as the speed increases after takeoff the stab position is automatically changed by the aircraft to reduce the out of trim forces,unless the pilot manually trims which cancels this automatic operation.CheersJon

[JHepburn 0]

Basically, trim can be used at any time to relieve the forces required to hold a desired nose attitde. Since power, wind and descent/climb all influence the desired nose attitude, a pilot can be trimming quite often. If you are practicing things like steep turns and the like, you wouldn't usually be constantly trimming in an aircraft like a C172. Usually, you trim for straight and level flight, but you could also trim when a stable descent or climb is desired. However, like I said originally, you trim to make the pressure in the yoke go away when trying to maintain a desired nose attitude.

I understand what trim does, but I'm asking what is typically taught in terms of technique. Since a turn is a transient maneuver, do you leave it alone so that you're in trim when you roll out? Or, do you trim the elevator forces out during the turn?

[downscc 1,327]

I forgot to mention the maneuver was indeed with steep turn, I think the FAA requires this maneuver with 45 deg bank although the 60 deg bank (2g) is much more fun. If you are good you will fly into your own wake turbulence.Every pilot has their own technique, but I don't trim during a turn, I add the back pressure without thinking about it. Thinking about it, most of the turns made that require this type of compensation are in the terminal area and other things are happening too like speed changes, flaps and altitude.I think everybody that wants to know what the controls feel like should go to their local airport and pay the flight school for an introductory flight. Flight schools would love to have your business and will usually give you a good price on a chance to go out and do a couple of turns, maybe a stall, and and a landing. Do it!

[Check_Airman 3]

Interestingly as the speed increases after takeoff the stab position is automatically changed by the aircraft to reduce the out of trim forces,unless the pilot manually trims which cancels this automatic operation.

Didn't know that, where in the FOM can I read some more info on that tidbit?Paul

[des182001 1]

I took a introductory flight in Augusta, GA and it was awesome. I got to fly a cessna 172 for 30 min and the instructor was surprised with how familiar I was with the aircraft (thanks Flight 1). He let me takeoff and I flew the whole time to include the approach onto the runway; he took the controls at about 500' AGL. He also let me trim the airplane for level flight and conduct a series of 30 degree left and right turns; the trim was not thouched during the turns so a small amount of back pressure was required to keep the cessna level.It was only $70 dollars and worth every penny. I'm planning on doing my PPL when my wife finishes college.

[Irishcurse 234]

I forgot to mention the maneuver was indeed with steep turn, I think the FAA requires this maneuver with 45 deg bank although the 60 deg bank (2g) is much more fun. If you are good you will fly into your own wake turbulence.

That was the first real adrenaline rush I had in my flying lessons. At first you think taking off and landing are a adrenaline rush, then stalls, but when you do a steep turns ( I did figure 8's ) and you are just coming wings level to start your turn to the opposite direction, you feel the shudder of your own wake is a rush. I love doing steep turns.As to the original post, you have to trim the aircraft. If you let the AP handle the approach, you will see the aircraft is trimmed pretty good when you disconnect.RegardsRichie

[Spin737 102]

Didn't know that, where in the FOM can I read some more info on that tidbit?Paul

Here's some 737NG copypasta for you, Paul. I don't think the classic has STS.Speed Trim SystemThe Speed Trim System (STS) is a speed stability augmentation systemdesigned to improve flight characteristics during operations with a low grossweight, aft center of gravity and high thrust when the autopilot is not engaged.The purpose of the STS is to return the aircraft to a trimmed speed bycommanding the stabilizer in a direction opposite the speed change. The STSmonitors inputs of stabilizer position, thrust lever position, airspeed andvertical speed and then trims the stabilizer using the autopilot stabilizer trim.As the aircraft speed increases or decreases from the trimmed speed, thestabilizer is commanded in the direction to return the aircraft to the trimmedspeed. This increases control column forces to force the aircraft to return to thetrimmed speed. As the aircraft returns to the trimmed speed, the STScommanded stabilizer movement is removed.STS operates most frequently during takeoffs, climb and go-arounds.Conditions for speed trim operation are listed below:

[Check_Airman 3]

Thanks Matt!I'll have a look at it next time I fly.Paul

[Spin737 102]

Thanks Matt!I'll have a look at it next time I fly.Paul

No problem. Just think of it as helpful runaway trim! ;)

[jon b 2,050]

Paul,Mat,I`m not sure where its written I`ll have a look in the manuals tonight on my way home to London(once I finish the newspapers!) just hidden somewhere in my memory. From what I recall the 747 works slightly differently from the 737 system you`ve pasted above, in that rather than helping to hold a particular speed it automatically adds nose down stab trim as you accelerate unless manual trim is used.Cheers Jon

[woodreau 0]

One of the "difficult" basic tasks that wanna be pilots have to master is a 360 turn left followed by 360 right (or right/left) without altitude deviating +/- 100 ft. No amount of practice in a simulator will prepare you for this.

Actually - it's no amount of real world flying in the actual aircraft can prepare you to do the steep turns in the level D simulator of the simulated aircraft. One of (at least mine anyway) the most dreaded things is doing an RPC (recurrent proficiency check) - never mind I've flown the aircraft for the last six months in real world conditions. Getting back into the box - I have to get some handflying of the simulator to get the feel of the simulator again before I attempt the flight maneuvers so that I can somewhat passably fly the stalls and steep turn profiles. - But never had to do steep turns in the actual aircraft (at least since my piston airplane days anyways.)But I can't answer the OP's 747 question - never having flown the 747, all I can offer is for sure, they shouldn't be having the control column pulled all the way back aft in the pilot's lap. But I don't think any pilot can really answer how much backpressure they are exerting on the control column - it's all subconscious and the pilot "maneuvers" his control column instinctively that there isn't a lot or much conscious thought applied towards what they're actually doing to the control column. We're not Commander Data, who can measure that he's exerting 30 hectonewtons (or whatever) of pressure against the control column. We just squeeze in some backpressure, see what it does - then either squeeze in some more, lets some out, or hold it there.Steve W.

[Check_Airman 3]

But I don't think any pilot can really answer how much backpressure they are exerting on the control column - it's all subconscious and the pilot "maneuvers" his control column instinctively that there isn't a lot or much conscious thought applied towards what they're actually doing to the control column. We're not Commander Data, who can measure that he's exerting 30 hectonewtons (or whatever) of pressure against the control column. We just squeeze in some backpressure, see what it does - then either squeeze in some more, lets some out, or hold it there.

That just about sums it up nicely. You just apply as much pressure is needed. If yo ever find yourself looking at the control column and thinking "how much is that deflected?" Something's wrong.If you've never flown a plane, it's a bit like asking how much you have to stretch to reach the top shelf of your pantry. You don't really think about it, you just do it.Paul

[ahaka 0]

But I can't answer the OP's 747 question - never having flown the 747, all I can offer is for sure, they shouldn't be having the control column pulled all the way back aft in the pilot's lap. But I don't think any pilot can really answer how much backpressure they are exerting on the control column - it's all subconscious and the pilot "maneuvers" his control column instinctively that there isn't a lot or much conscious thought applied towards what they're actually doing to the control column. We're not Commander Data, who can measure that he's exerting 30 hectonewtons (or whatever) of pressure against the control column. We just squeeze in some backpressure, see what it does - then either squeeze in some more, lets some out, or hold it there.Steve W.

That of course makes sense. :)The reason I asked was that in PMDG 747 I sometimes find the need for extreme control positions. I found this out when making the IGS approach at Hong Kong's old Kai Tak airport. Although the airplane is perfectly trimmed for the ILS, the last minute turn to the runway sometimes asks for extreme positions, especially with strong crosswinds. The PMDG MD-11 handles differently, needing less input on the controls.