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Trimmed to land

Posted By: Greybeard

Trimmed to land - 03/14/12 11:35 AM

Mybe I'm reinventing the wheel, but would anyway to share how I improved my landing abilities (pretty poor, indeed) lately, increasing elevator trim about 15 "clicks" up before landing. First touch is critical and must be as soft as possible, keeping a/c as long as possible up, like if you would hamper it from touching down, cutting very slowly throttle, since a sharp cutoff would roll a/c upside down.... Curiously, this is much more difficult than in reality, at least with a light aircraft, where you "must" cutoff throttle and that can absorb some shock on landing without jumping like a cricket! smile

I'm speaking of 4.10.1. In 4.11 I think this has been addressed, since I notice much less "ricochet" (that's to say better shock absorbing). Unfortunately, some exaggerated ground effect was added, forcing a/c like FW190 to endless run a few feet over runway, before they touch down.

GB
Posted By: rollnloop.

Re: Trimmed to land - 03/14/12 03:44 PM

I always trim full up during final, it's much easier that way indeed, especially since our joysticks are usually less precise near the stops (but in a real plane it's almost the same, one is less precise when strong force needed), those fighters are usually very nose heavy at slow speed. The other thing is to approach at 1.3 stall speed, if you have trouble with any type of aircraft take it level at 1000m, gear and flaps down, idle power and full trim up, trying to keep altitude as speed comes down. When you feel the first stalling signs, note the speed, push down to recover and once you get 1.3 the stalls speed, increse power to go back level. Do your approach at this 1.3 stall speed, reduce gently power while flaring to get nose higher than horizon and keep it there, then wait. If too high, release the stick almost imperceptibly to limit bounce. If flare was too low and aircraft bounced high (provided gear hasn't collapsed), go around and try again.

It's quite comprehensible you don't have as much torque effect when changing power in a light aircraft, most don't have those fighters' 12ft props !

Happy landings smile
Posted By: Tolwyn

Re: Trimmed to land - 03/15/12 01:06 AM

Yowza, guys.
I neutralize trim as much as I can on a landing, as in real life.
Grey, my guess is you're coming in too steep, which is typical for most sim pilots. Most sim pilots want to see the entire run way out their cockpit, when really, you need to approach longer and more shallow. Fly the aircraft TO the runway.

Try the notion of flying the aircraft TO the ground, instead of floating the aircraft onto the ground.
Posted By: Tolwyn

Re: Trimmed to land - 03/15/12 01:06 AM

By the way, I have to say in real life in all the aircraft I fly, it's rare I even touch trim unless I'm flying long distances, and only then to ease fatigue I need to place on myself on the yoke.
Posted By: Nimits

Re: Trimmed to land - 03/15/12 03:36 AM

Really? 'Cause in every plane I've flown, GA or otherwise, I'm trimming after any significant pitch/power change.
Posted By: DGC338

Re: Trimmed to land - 03/15/12 07:09 AM

With you Nimits. Make a change, hold, trim. Like that in every aircraft I've flown apart from flying at very low level. Trim nose up so If you release you climb. The only other case where I don't trim is in aero's or in FBW aircraft.
Posted By: Greybeard

Re: Trimmed to land - 03/15/12 10:09 AM

rollnloop

I tried and it works! Curiously, it matches exactly what required by FIAT G50bis Pilot's Manual! Do you trim also for take-off?


Tolwyn

I think your way applies more to a carrier landing (land w/o flare), although I confess I tend to stay high and in a steep descent: an habit coming also from many real landings on a short runway, among relatively high obstacles (wires, trees, buildings).
In two years, I too used trim only once, but must be said I flew all short flights.


Nimits, DGC338

That's the right thing to do for long flights, I think, but when you go up for a short time, at low altitude, time spent to balance a/c becomes a significant part of the total and sort of wasting. IIRC, trim should be slightly nose-down, though, otherwise if you release risk stall.

S!
GB
Posted By: Tolwyn

Re: Trimmed to land - 03/15/12 07:59 PM

Carrier based aircraft have a MUCH more forgiving gear structure. I was literally referring to landing on a good ol' runway.
Posted By: Tolwyn

Re: Trimmed to land - 03/15/12 08:02 PM

Originally Posted By: Nimits
Really? 'Cause in every plane I've flown, GA or otherwise, I'm trimming after any significant pitch/power change.


To fly coordinated or to counteract fatigue, right? But do you trim for landing? What I mean is... actively? Well, I guess any adjustment is trimmed (the aircraft is ALWAYS trimmed, I guess).

In landing though, I don't know about you, but I wouldn't touch my trim wheel. smile
Posted By: Nimits

Re: Trimmed to land - 03/16/12 02:37 AM

On a GA aircraft in a VFR pattern, it probably depends on where the trim is. Trim button on the yoke, and I am going to at least get the trim moving in the direction of neutral for a short final configuration/descent slope; if it is a wheel on the floor, maybe not. Granted, its not as if the stick forces on a PA-28 or a C-172 is going to be that hard too handle in any reasonable trim/power/CG configuration, but I feel it is good habit.

On anything faster/heavier, though, I'd definately trim for final, especially on a instrument approach, just like I would trim for slow flight, or any other manuevers. Don't know if that is normal or not, but it is the way I've always done it.
Posted By: rollnloop.

Re: Trimmed to land - 03/17/12 05:24 PM

Quote:
In landing though, I don't know about you, but I wouldn't touch my trim wheel. smile


Probably the misunderstanding comes from when one considers "landing" start. Of course, aircraft must be trimmed during final, not while flaring.

@Greybeard: for take off, i only rudder trim mostly. At start up check wich direction prop is turning over cowling: left to right--->trim rudder right. right to left---->trim rudder left. Trim pitch neutral, then, if after a few take offs you see that this particular aircraft needs much pushing on the stick while leaving ground , trim pitch slightly for dive. If it needs much pulling, trim slightly for climb.
Posted By: Greybeard

Re: Trimmed to land - 03/18/12 11:09 AM

Originally Posted By: rollnloop.
@Greybeard: for take off, i only rudder trim mostly. At start up check wich direction prop is turning over cowling: left to right--->trim rudder right. right to left---->trim rudder left. Trim pitch neutral, then, if after a few take offs you see that this particular aircraft needs much pushing on the stick while leaving ground , trim pitch slightly for dive. If it needs much pulling, trim slightly for climb.


Parfait!

Thank you,
GB
Posted By: Fishingnut

Re: Trimmed to land - 03/20/12 04:59 AM

Originally Posted By: Tolwyn
Yowza, guys.
I neutralize trim as much as I can on a landing, as in real life.
Grey, my guess is you're coming in too steep, which is typical for most sim pilots. Most sim pilots want to see the entire run way out their cockpit, when really, you need to approach longer and more shallow. Fly the aircraft TO the runway.

Try the notion of flying the aircraft TO the ground, instead of floating the aircraft onto the ground.



Well you sure are different from me then, because I'm also a real life pilot but I usually fly a steep approach in IL2. Mostly because the steeper the approach, the less throttle you need and therefore the torque affects your landing less, so this requires less correcting rudder. Since I come in steeply, I simply start the flare up a bit higher but that's easy to get used to. The lessened torque also means less wing drop to one side if you get a little too slow too high in the flare. I think a real fighter pilots landed fairly steeply in real life mostly so they can get that nice view of the runway that you seem to think is soooo bad. What's wrong with a great view on approach? I just like the 'chop and drop' technique, works well as any other way once you get used to starting to flare a bit higher and the low torque also makes it easier to stay in the enter of the runway without fidgeting with heavy ruddering.

As far as using neutral trim like someone suggested, this does not work in the sim well. Nor does it work well for all real-life aircraft either. Try to land a Cessna 182 or 205 with neutral trim and give me a call from your hospital room!! A lot of up trim on most Cessna high winged planes is a good idea because they are notorious for being really nose heavy. Not so much to the 152s or 172s but a 172 still has me trimming up a quite a bit. What types of planes are you guys flying or are some of you just saying your pilots and you're really not?
Posted By: Tolwyn

Re: Trimmed to land - 03/20/12 07:43 PM

I never said having a big view was bad! I meant that because of the nature of the game (monitors) sometimes you come in steep so you CAN see the whole runway. I've never flown any high-performance aircraft. I was very much speaking in generalities, but I tend to fly the airplane TO the runway instead of floating it ONTO the runway. Maybe I just didn't say it right. wink

Hey, I think you should do whatever works for you in the game. I wasn't preachin' !

Hmmm. I've not ended up in the hospital yet. Although I've never flown a 205. I'm more of the 152, 172 variety, so my experience seems limited.

I'm a pilot. Got lots of video, however, i'ts getting too expensive and my 10 year old makes it hard for me to justify the cost anymore. frown I did see a Citabria at Oshkosh 2 years back and I SO SO SO wanted to buy it. Oh, man. Didn't even know they still manufactured them.
Posted By: Nimits

Re: Trimmed to land - 03/20/12 09:14 PM

For GA, PA-28-140/150,mostly; C-172 at times, a little in a DA-20C. Personally never cared for the C-172, but their is an FBO about 5 minutes from where I live now that has a couple of C-172s, while the closes Pipers or Diamonds are 30-45min away (and in the opposite direction of where I'd want to go cross country).

IRL, flat approaches can appear easier, I've seen, but I've found most CFIs prefer steeper approaches for visual patterns, mainly on the theory that if the engine quits, you can still make the runway.
Posted By: Fishingnut

Re: Trimmed to land - 03/21/12 02:13 AM

At the airport I used to hang out at, they had one 172 that you absolutely had to trim up to land, even with no load other than yourself in the cockpit. If you threw some baggage or a person in the back you didn't have to. If you tried to land with neutral trim in most circumstances you'd run out of elevator with the yoke against to back stop about the time the stall went off and that could cause a hard landing or even a nose-wheeler. That thing was really nose heavy.

One time I took off in a hurry and somehow missed the line on the checklist for setting the elevator trim to takeoff trim ( which was marked ) and I tried to take off with the trim where someone had left it at the previous landing. Well, they had it full up trim set!! So when I rotated I ballooned into the air with the stall horn screaming!! Needless to say I nearly pee'd myself and had I not pushed forward on the stick really fast, I might no be writing this now. Plus I castigated myself for months for being so careless with checking off checklist items!! I think it was about a month before I flew again......All pilots make scary mistakes at times, I'm just the only one stupid enough to admit to them. My main point being though that particular Cessna 172 had people trimming up a lot for landings.
Posted By: Tolwyn

Re: Trimmed to land - 03/21/12 06:40 PM

People still don't believe me when I tell them hanky-sucking to test your stall horn is part of the pre-flight checklist.
Posted By: EinsteinEP

Re: Trimmed to land - 03/21/12 07:11 PM

Trim doesn't change how far the elevator can go, just the force needed by the pilot to maintain a given control position for a given aircraft condition (weight, airspeed, altitude, etc.). Folks going from nimble/light aircraft, like the Cessna 152, often have problems with the additional oomph needed to flare in a heavier aircraft like the C172 or C182 on their first few flights. Trimming does help reduce the force required to flare, but it doesn't magically extend the elevator. It's possible that whoever was having problems with landing that Cessna was trimmed for level flight (more nose down), not descent (more nose up), which is a big difference. Had they been trimmed properly, even with a forward CG, they would have had no problem controlling the aircraft through touchdown.

Setting the trim to full nose up causes problems not only for the pilot who flies afterwards and doesn't check their trim wheel (see Fishingnut's great learning story above) but could also be a significant problem for the landing pilot: trying to execute a go around by pushing in the power will cause the aircraft to pitch up sharply, losing airspeed and causing the pilot to fight the controls to prevent a stall. In fact, I'd go so far as to say that setting the trim full in any direction is always a bad idea - the trim should be set to just what is needed, no more, no less. If a pilot needs full trim one direction or the other to maintain control of the aircraft, they're probably in more trouble than they realize.

In real life, I was taught to trim often and I found it really helped the stability and smoothness of my flying. I learned to trim whenever I felt any force on the yoke, including simply maneuvers like level turns (tilt the yoke with one hand to begin the turn, spin the trim wheel down a couple times with the other to maintain altitude, reverse the process for leveling out). Trim, trim, trim, trim, trim, trim, trim... Took a lot of the work out of my arms and put it into the trim tabs, which never complained about the extra duty.

There are pilot preferences on whether or not to trim a force against the stick or to trim forces out (aka neutral trim). My preference is to trim neutral (i.e., no input force needed to maintain descent attitude) and have used this approach in real life on Cessna 152s, 172s, 140s, Piper cubs (J-3), PA-12 Super Cruisers, and a Stinson 108 and also have not spent any time in a hospital.
Posted By: Tolwyn

Re: Trimmed to land - 03/21/12 10:03 PM

Thank you, Einstein. I was explaining this to a friend of mine even before I started reading your post and I found myself saying...

SEE??
Posted By: Boilerplate*

Re: Trimmed to land - 03/22/12 01:25 AM

Originally Posted By: EinsteinEP
Trim doesn't change how far the elevator can go, just the force needed by the pilot to maintain a given control position for a given aircraft condition (weight, airspeed, altitude, etc.). Folks going from nimble/light aircraft, like the Cessna 152, often have problems with the additional oomph needed to flare in a heavier aircraft like the C172 or C182 on their first few flights. Trimming does help reduce the force required to flare, but it doesn't magically extend the elevator. It's possible that whoever was having problems with landing that Cessna was trimmed for level flight (more nose down), not descent (more nose up), which is a big difference. Had they been trimmed properly, even with a forward CG, they would have had no problem controlling the aircraft through touchdown.

Setting the trim to full nose up causes problems not only for the pilot who flies afterwards and doesn't check their trim wheel (see Fishingnut's great learning story above) but could also be a significant problem for the landing pilot: trying to execute a go around by pushing in the power will cause the aircraft to pitch up sharply, losing airspeed and causing the pilot to fight the controls to prevent a stall. In fact, I'd go so far as to say that setting the trim full in any direction is always a bad idea - the trim should be set to just what is needed, no more, no less. If a pilot needs full trim one direction or the other to maintain control of the aircraft, they're probably in more trouble than they realize.

In real life, I was taught to trim often and I found it really helped the stability and smoothness of my flying. I learned to trim whenever I felt any force on the yoke, including simply maneuvers like level turns (tilt the yoke with one hand to begin the turn, spin the trim wheel down a couple times with the other to maintain altitude, reverse the process for leveling out). Trim, trim, trim, trim, trim, trim, trim... Took a lot of the work out of my arms and put it into the trim tabs, which never complained about the extra duty.

There are pilot preferences on whether or not to trim a force against the stick or to trim forces out (aka neutral trim). My preference is to trim neutral (i.e., no input force needed to maintain descent attitude) and have used this approach in real life on Cessna 152s, 172s, 140s, Piper cubs (J-3), PA-12 Super Cruisers, and a Stinson 108 and also have not spent any time in a hospital.


Yes. That's the way I remember using trim in Flight Simulator II back in 1985. yep
Posted By: Dart

Re: Trimmed to land - 03/29/12 11:49 PM

Quote:
What types of planes are you guys flying or are some of you just saying your pilots and you're really not?


I fly a Champ and found that trim is Of The Devil.

Set it for easy flight at 60 MPH (about a half an inch back from center with just me) and leave it alone!

One hand on stick and one on throttle while landing, please, as one doesn't have a third hand to put above the window for trim.

I do the same in flight sims - trim for cruise and stop dinking with it.
Posted By: Greybeard

Re: Trimmed to land - 03/30/12 10:46 AM

I too think trimming for cruise speed is best for all the flight, both for real and in sim. Light planes have almost same speed for take-off, climb, cruise and descent, while during sim, speed varies so often that I think it's hard to keep it constantly trimmed. Perhaps could be interesting some of following readings:

Trim for Angle of Attack!

Trim Won’t Solve All The World’s Problems

Use Outside References and Trim

Cheers,
GB
Posted By: EinsteinEP

Re: Trimmed to land - 03/30/12 07:47 PM

Grey, the articles you referenced actually support changing trim, not leaving it set for cruise speed.

Trim for Angle of Attack!
"Trim for airspeed at 1 G. Airspeed depends on trim."
Airspeed at cruise and airspeed during an approach are quite different in light aircraft.

Trim Won’t Solve All The World’s Problems
"Put the pitch attitude where it belongs, keep it there with the yoke, and then trim off the pressure."
Pitch attitude at cruise and pitch attitdue during descent is quite different in light aircraft.

Use Outside References and Trim
"Trimming the airplane for the desired angle of attack and flying with a light touch on the controls is also exceedingly helpful in maintaining a definite value for angle of attack."
Angle of attack at cruise and angle of attack during approach is quite different in light aircraft.

And, if an aircraft's airspeed is constantly varying, then the pilot doesn't have very good control of their aircraft.

That said, I still believe the use of trim is up to pilot preferences. If pilot needs/wants to have that tacticle feedback during approach, then they can either trim that force in or, if cruise trim isn't far enough off, they can leave that trim in. It's not important that every pilot flies with the exact same technique - it's important that every pilot flies with the technique that's best for them.
Posted By: Neal

Re: Trimmed to land - 03/30/12 08:12 PM

Originally Posted By: Fishingnut
If you tried to land with neutral trim in most circumstances you'd run out of elevator with the yoke against to back stop about the time the stall went off and that could cause a hard landing or even a nose-wheeler. That thing was really nose heavy.


I don't get why you'd hit a limit with neutral trim (as opposed to nose up) but I don't know what else a change would include for you. Perhaps different speed? Something else you didn't mention?

I think it would make a difference in a plane with stab trim like a 109, wouldn't it?


Posted By: Greybeard

Re: Trimmed to land - 03/31/12 09:44 AM

Sorry, I failed to make myself understood. I meant that was just my opinion, but I remained open minded to different ones, especially those by credited authors, like those linked, meant to give a wider view on the matter.

Originally Posted By: EinsteinEP
... I still believe the use of trim is up to pilot preferences.


Well said, much wise.

Cheers,
GB
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