So recently got the Comanche and it blows me away how easy this thing is to trim. I did a short hop yesterday above some quite hilly/mountainous terrain. It was quite choppy, but that thing pretty much stayed dead on level for the entire flight with barely any readjustment. It stays so level that using the ALT hold on the AP almost seems redundant lol.
So I decided to fly the route again in a few other aircraft. The 152, the Beaver, and the RV-14. These were all way more of a handful. They all required constant adjustment and there were a lot of times the aircraft would sink or rise without any change in pitch - which I guess is the result of sinking or rising air, but I never experienced those moments in the Comanche.
So whatās the deal here? Is MSFS just too sensitive compared to real life. Or is the Comanche too stable?
it dependsā¦. I guess that is how an answer to your question has to start. The wing loading and the overall control balance of the aircraft in question has a lot to do with how it flies IRL.
Even fairly similar aircraft can fly very differently and in certain situations the pilot is the most crucial factorā¦ control inputs usually have more than one result. Pitch up will increase drag, decrease speed, increase liftā¦ā¦
However at least in most GA airplanes, if you did not touch the power controls, the aircraft will return to the previously trimmed stateā¦maybe after a few oscillations and be fairly stable again.
If the pilot however adds control inputs again at just the wrong moment, he can upset that balance again and the cycle starts over, sometimes with bigger amplitude than before.
The Cessna C210, Beech Bonanza and Piper Saratoga are all very stable aircraft. Once trimmed they just fly along happily with very little input required. Even in conditions where their smaller siblings are much more demanding of their crew.
But at least on calm days or evenings even a very light C150 is quite easy to trim for pretty much hands off flyingā¦.but she will need a more frequent nudge to stay on course and wings level.
A Citabria, or SuperCub are much more agile in every sense and are never as stableā¦so they are also not easily trimmed for long.
A Stephens Akro is so squirrels it never really trims out. But you just think of what you want it to do and it is already going in that direction.
in the sim you are missing, usually at least, the most important thing. How do the controls feel in flight. How much force do you have to apply to create a reaction or the other way around, how much force can you apply without upsetting a stable aircraft.
In the real airplane you hold the aircraft where you want it and then trim away the force you feel in the controls. After that you make one or two small adjustments and it is done.
In the sim you do not have that. You react to a gauge for VS and that just simply doesnāt work as well. And the return to trimmed state also doesnāt work as well, with some aircraft. The Comanche is a good example for other developers.
One small edit thoughā¦ even the most stable aircraft can not smooth out all the potholes in the sky. If you fly through unstable adjacent air masses you are going for a ride. And even in a heavy like a C210P or a Saratoga you will need to tighten those belts.
In mountainous areas you can encounter airmasses that overpower your aircraftā¦I ran into that once flying into Aqua Dulce in the Saratoga, by being sloppy to be honest, and needed all 300 horses and probably a little lift from my guardian angel to arrest the sinker I had flown into.
Thanks for that. It all makes a lot of sense. I get that sinking or rising air a fair bit in the other planes on the sim where the VS gauge will fly up or down by 1000fpm without any change in pitch, but the Comanche doesnāt seem to experience this much at all. How common are these air potholes IRL?
Generally speakingā¦it is usually the most stable early in the morning or in the evening and into the night.
The ground texture and topography has a lot to do with it of course.
Any large bodies of water nearbyā¦also a big influence in the air. And then of course it depends a lot on your altitude. Down low you can usually expect more movement but it also is dampened somewhat because some of the energy is lost in trees and ground ondulations.
However very close to those same trees, buildings or hills etc you can experience strong turbulence that does not even register a few hundred feet higher.
Last but not leastā¦.is it a sunny day or overcast? The sun creates turbulence simply by heating the ground, and because that is usually not really uniformly it will create potholes.
Even the ground color can make a difference when it comes to thermal updrafts and downdrafts. The lowest layer of the atmosphere is subject to all sorts of friction, orographic lift, and other convective currents.
How high those effects reach depends on a lot of factors. Of course, the jet stream, strong mountain waves, convection from storms, and simple changes in wind aloft can cause turbulence at higher altitudes.
That said, I find the sim does overstate thermal lift a bit for GA aircraft, especially over longer periods of transit.
I recall one flight in a C172 from Johannesburg to Cape Town in South Africa in the 80ās. It was a very hot day over a semi-desert area. At one stage we hit the worst air I have EVER encountered. In quick succession (at around 7,500ft IIRC), I went from full throttle, nose pitched up, 70kts IASā¦ and going DOWN @ 1,000fpm! Next moment: nose down, almost idle power, 120ktsā¦ and going UP @ 1,000fpm! Seeing as it was a sparsely populated area with essentially zero traffic, I very quickly gave up on that and just flew a fixed attitude at turbulent air penetration speed and just the air to throw me around at around my planned altitude. That was extreme and VERY tiring and trim was useless.
Second worst was in another hot region, flying along some mountains on a hot day. Not the huge up and downdrafts but absolutely JARRING turbulence that was relentless and extremely uncomfortable for all of us. Another turbulent air penetration speed flight.
And then the other extreme: flying in the cool of the evening/night in anything from a C172 to a C210 or Bonanza. Like sitting in a comfy lounge chair, just suspended, apparently motionlessly, in the air. Trim and forget. One of the incredible pleasures of small aircraft flying that I will always treasure.
If you want to get into the weeds a bit, but maybe come away with a deeper understanding of what trim is, why itās necessary, and how we use it, hereās a link to an answer I provided in a thread about this very aircraft. It goes a bit further than just the application of trim in turbulence and remains applicable to most aircraft.
In my specific Cessna 152. Its very easy. I hardly ever have to touch the wheel and when i do its a very simple nudge. MSFS is not very realistic when it comes to trim and thats also due in part to the physical controls and users have. In real life its actually very easy.
Thatās the biggest takeaway. Trim basically sets the neutral point of the tail-down force with respect to balancing the pitching moment for the torque provided by the current weight, cg, and lift vector from the wing. The effect we feel as pilots is we donāt have to hold the elevator in place with the yoke to achieve that balance.
With the sim, weāre dealing with numbers and springs instead of physical aerodynamics, so trimming instead just moves the stable point of the pitch moment in the sim to wherever the spring tension is centered, kind of a backwards workaround. But it kinda works.
Where it causes issues is that we donāt have any aerodynamic tactile feedback, nor the seat of our pants feel when turbulence or thermals, whatever, knocks us out of balance, which, when combined with visual proprioception allows us to make instant, small adjustments with the yoke when stability is upset. Note this is also the thing that can kill you when you donāt have visual of the horizon as in night and/or IMC conditions.
So we end up fixated on the instruments and chasing the needles when in visual conditions in the sim, which is what weāre not supposed to do in real life (just verify with quick glances).
That said, I feel like with enough practice, you can get pretty good at it in the sim, itāll just be a little different than real life. Iād say the majority of the issues in the sim are people who just donāt understand how to apply trim correctly (as it applies to the sim and/or reality), some just havenāt practiced enough, and the rest is exacerbated by some issues with (lack of) inertia and overbearing thermal lift. Iāll add that hardware can play into it as well.
IRL trimming small GA plane is much easier than in sim: you apply the elevator pressure you want for given airspeed + climb/descend, then with trim you neutralize the force you exert on the yoke. When you no longer feel the force - you are properly trimmed.
To have the same in sim you would need expensive force feedback yoke like Brunner. You may also consider modding ordinary yoke just for the natural trim:
Exactly. Itās very simple. Trimming IRL is just adjusting to the point you donāt need to push or pull to keep the yoke/stick in the position you want it in. Thatās all it is. Yokes/stick IRL donāt have a center position like they do when using sim hardware with springs.
Itās not really about keeping a constant V/S. The main purpose is for your hands to not get tired. If youāre not trimmed correctly keeping the elevator where you want if might actually require quite a lot of force.
Obviously if youāre in turbulent air you donāt retrim the aircraft constantly. It doesnāt make sense.
The best implementation in cheap hardware without force feedback I remember was in the CH Yoke. It had a ātrimā wheel that physically moved the yoke shaft back and forth. But it was a very cheap yoke and not very precise so the usefulness was limited, but the idea was great.
Fascinating. Even though Iāve read it a fair few times I still canāt quite wrap my head around the concept of trimming for airspeed. It always feels like youāre taking power and pitch to change the attitude of the craft (level, descend, climb) and relieving pressure from the controls.
Iāve been trimming a lot more now I have a TB Velocity One with nice trim wheel and lately experimenting with adjusting power and then leaving the controls alone to observe what the aircraft does. Iām realising Iāve been āfightingā the plane rather than working with it.
One of the first things they drill into you in flight training is āattitude, power, trimā. Itās like Mr. Miagi in The Karate Kid: āwax on, wax offāā¦ Later, they will even cover the airspeed indicator on you so you canāt see it. You need to be able to set the airspeed to your nominal speeds (e.g. normal cruise, Vx, Vy, etc), based on the tach and noseās attitude relative to the horizon. But trim is last in that list. You set the attitude with the yoke, set the desired power and then trim.
Iāve started to adjust throttle to put myself in a climb or descend then control / adjust pitch then trim. And I guess I am always looking for the speed appropriate to the plane in that phase. Is that wrong or just a slightly different way of achieving the same thing?
Edit: adjusting pitch and power happen almost at the same time. Iām making sure to fly with left hand on yoke and right on throttle.
Iāll leave it to @CharlieFox00 to explain. Heās an instructor of sorts and has a way with words. But ahead of his input Iād say āit dependsā.
Fine. I will take a stab at itā¦ It depends in so far as you might want to climb at a higher speed than Vy in a cruise climb, or ATC might ask you to keep the speed up as you descend towards an airport. The latter is a scenario encounter frequently in the C172 that I fly. In that case, I might just reduce the power from my cruise power setting and donāt touch the trim. Then when they want me to slow down, Iāll reduce throttle some more as I add up elevator to pitch for the new speed and then trim once Iām stable at the new speed, using power to regulate my rate of descent. My instructor would have had me slow the aircraft down by pulling the power back to a high idle, pitch for the new speed and then add power back in, but these days I tend to do it more āall togetherā.
Edit: Another example of where youād be juggling pitch, power and trim is in the pattern for landing. Iām just a low time pilot, having only finished my PPL about a year ago, so I still mostly do things the way my instructor wanted. He had me do 80 knots on downwind, 70 on base and 60 on final in the C172, with flaps 10, 20 and 30 respectively. When you turn to base and set flaps 20, you actually have to add power and/or pitch nose down a bit to avoid slowing below 70 knots. Then once youāre stable, you trim. It all happens faster in real life than in the sim.
