RealTrim

[Guest wyoming]

I find it very good and it somehow feels natural... I can't remember if Active Camera can move your "head" vertically to give the visual equivalent of the G (havent's reloaded evrything yet) but that would work very well with it. Been back to FS after a long break and with a new rig, I had just noticed a very large increase in my use of the trim and just then this neat utility comes out. Thanks to the creator!

[Rudi 0]

It's yoke, not yolk.

[Rudi 0]

I've been following this thread too and I think I like the FAA method better, the one Cindy was talking about. Jim's technique sure does involve a lot of trimming. I think Cindy's right because I too look at the trim wheel and note the setting after I've trimmed stick pressure off. It's sort of a double-check in a way. Moreover, I don't constantly adjust the trim setting as others in the AOPA thread talked about; I just set it once for the desired airspeed and the airplane flies itself so nicely. As for leveling off, I certainly don't mind holding a little forward pressure on the stick while the airplane stabilizes - it's not that much physical effort and I think the technique permits me to feel the proper trim setting for level flight better than were I were to trim incrementally.Anyway, the important idea I picked up during this thread was the notion that it's important to look and know the trim setting for different airspeeds. I agree that trim correlates with airspeed and can see Cindy's point that there is only one trim setting for a given phase of flight, assuming of course that each phase corresponds with a desired airspeed. And Jim of course is correct that lift is affected by air density. So the actual position of the trim tab may vary with changes in air density and loading, for example, but the nature of the relationship between trim and airpseed is still linear meaning that there is only one trim setting for any given airspeed - so I guess they're both right in their own way. But since light aircraft fly in a limited altitude range it seems that any correction to the trim setting for a specific airspeed would likely to be pretty small - I think.A while ago at our field there was a pilot who took off on an IFR flight who experienced a bird strike that took out the pitot tube, and then when returning back to the field experienced a vacuum failure - in IMC - so no airspeed, attitude or DG - but got back down on the ground safely. I remembered this story (urban myth??) after reading this thread and tried to replicate this using FS. I guess I'm such a habit of looking at the trim setting that I remembered that I could fly the aircraft using just the power, turn coordinator, compass and trim setting as a proxy of airpseed. I don't want to diminish what must have been a pretty hairy experience (if this this did actually happen) but frankly I found that it was not terribly difficult to maintain positive control of the airplane, maintaining specific altitudes and headings, in simulated IMC conditions, on the computer just using the power and trim settings, TC and Mag comp. The times between navigation waypoints even worked out so I think I was flying the correct airpseeds, too. This, I thought, was kinda cool!

[Guest Adverse Yawn]

Rudi,>>lift is affected by air density. So the actual position of the trim >>tab may vary with changes in air density and loadingActually, the trim position isn't affected by air density. It would be if we managed our flights using TAS. All pilot references are through IAS (or CAS depending on the instruments). There are four things that affect trim: Power setting, IAS/CAS, weight and CofG. Power because the slipstream over the wings/tailplane and/or thrust/drag couple is affected. IAS/CAS because that is the refernece speed that the a/c thinkgs it is flying at. Weight because as you inferred an increased wingloading required a higher angle of attack: CofG because a more rearward CofG reduces the angle of attack.>>experienced a bird strike that took out the pitot tube, and then when >>returning back to the field experienced a vacuum failure - in IMC - >>so no airspeed, attitude or DGI imagine loosing the ASI is a pretty hairy experience, fortunately not something I have had to deal with. A friend of mine is a test pilot, he basically does the initial post maintenance test flights. On one incident he found the airspeed slowly decreasing after take-off. By definition, the job means flying unfamiliar aircraft so one wouldn't have such references as trim to work with. He went by the combinaton of control mushyness, power setting and wind noise. He did admit once back on the ground that he should have switched the GPS on as ground speed would have been a handy input too!Back to your story. What kind of aeroplane was it? The pitot will only affect the ASI (airspeed indicator), not the DG or altimeter. In fact it is inconcevable that the DG and altimeter systems could have been affected by a single bird strike located on the pitot.

[Guest Cindy_Zoonan]

Rudi what airport are you talking about

[Guest av84fun]

First let me say that this aspect of the thread delves into highly complex aerodynamic issues such as L/D ratios etc. and I do not intend to use too much bandwidth to discuss the matter. I will therefore, keep it pretty simple but your mistaken notions do point out the misinformation and honest misunderstandings surrounding many things related to aerodynamic lift.<>Sure it is. See below.<>You might not but the airplane does. The WINGS could care less what your AI might read. Your WINGS care about the VELOCITY of air passing over and under them. Aerodynamically speaking, "velocity" is defined as TRUE AIRSPEED. (see below)<>It is also well known that at a given power setting, an aircraft will CLIMB faster in lower density altutude conditions than at a higher density altitude. Therefore, in Cindy's example, in which she cited a SPECIFIC RPM setting, she said she could know in advance, at what precise point to set the trim wheel. That would, of course, be impossible because in LOWERER temperatures and the related lower density altitude, the wings will generate greater lift. Therefore, to target a GIVEN rate of climb, MORE TRIM (or yoke pressure) would be required because more lift is being generated.Also see the following definition of "velocity"...which is TAS and it is well known that VELOCITY (TAS) and not IAS is what affects lift.<>Source..David F. Rogers, author Laminar Flow Analysis.For further study, consult the following"<> The Complete Soaring Pilot's HandbookI understand where you are coming from and this discussion (but not Cindy's which is just flat wrong) is one of those half full/half empty discussions.For example, will an aircraft stall (proving a loss of lift) at roughly the same INDICATED airspeed regardless of altitude...density or otherwise? Roughly, yes, so your suppositions about the use of the AI to reflect the state of lift is fine, as far as it goes.But the issue is TRIM and trim's purpose is solely to offset...one way or the other...the airplane's tendency to climb or descend with a GIVEN input of yoke pressure. Therefore, it is inarguable thatmore or less lift will be generated due to variations in density altitude and therefore, there would be more or less lift to offset by use of the trim wheel and therfore, the trim SETTING must be variable as density altitude varies...assuming a GIVEN power setting, which was Cindy's scenario.Regards,Jim

[Guest av84fun]

Hi Rudi,<>Yes, but Cindy's method requires a LOT of physical force being applied to the yoke for quite a while, whereas activating either a trim button or wheel would require only momentary application of a relatively tiny "force" that could easily be applied with your baby finger.Try holding MAJOR forward yoke during the entire transition from climb to cruise speed...with your baby finger...and you will quite likely dislocate your middle knuckle! (-:In addition, leaving trim at its CLIMB setting all the way to CRUISE would result, by definition, in a near maximum OUT OF TRIM condition (upon reaching cruise speed and never having touched the trim wheel. That's just NOT a good idea from any point of view, including safety.<< think Cindy's right because I too look at the trim wheel and note the setting after I've trimmed stick pressure off. It's sort of a double-check in a way. >>Different strokes for different folks Rudi, but I don't even recall the last time I even LOOKED at the trim wheel...in flight. (Of course, we look at it on the ground as part of the pre-take off checklist).I don't think many other pilots look at or care about the trim wheel SETTING in flight because the proper indication of whether the aircraft is trimmed is readily determined by FEELING whether any forward or backward yoke pressure is required to maintain the flight condition that we wish to accomplish.<>Maybe you have MUCH stronger arms than most of us have but if your airspeed has increased by FIFTY PERCENT which would be typical for a light single that climbs out at 80 kts and cruises at 120 kts. then there will be A LOT of forward pressure required if your remain trimmed for climb speed but have reached cruise speed.<>No such thing as THE TRIM SETTING for any given airspeed. Sorry to disagree...but you also contradicted yourself when you wrote:<>That is correct Rudi. <>OK. Not being an aerodynamicist, I don't know whether the relationship between trim and airspeed is linear...but I doubt it.But that is beside the point. When you suggest that "there is only one trim setting for any given airspeed" you are missing the point of trimming. You don't trim for AIRSPEED...DIRECTLY...you trim for the CONDITION OF FLIGHT that you wish to maintain...either a climb, a descent or level flight. Of course you GET an airspeed when you have achieved the condition you intend to achieve but you don't TRIM for that airspeed. You TRIM solely and exclusively to RELIEVE THE NEED FOR MANUAL ELEVATOR PRESSURE REQUIRED TO ACHIEVE THE INTENDED FLIGHT CONDITION....PERIOD. :-)And that truism is at the very heart of this whole trim methodology issue. The trim's only purpose is to RELIEVE the necessity for manual yoke pressure for a given regime of flight and since that is true, simply logic suggests that if it is there to help you, you should USE it.The related and overwhelming argument is that if you don't use it for the transition between climb and cruise flight, then you are INTENTIONALLY allowing the airplane to reach a near maximum OUT OF TRIM condition which just makes no sense.Just in closing, I share YAWN's skepticism of the bird strike myth but let me cite that kind of thing as a powerful argument against NOT triming off forward yoke pressure during climb out. What if, Rudi,that bird strike...which has happened to me and which I PROMISE you is a DRAMATIC event...one that would necessitate an immediate trip to the nearest laundramat after landing...Now, what if that bird strike happened JUST AS you had reached cruise speed and where holding significant forward yoke pressure...because you had not trimmed incrementally (at the "cost" of a few flicks of a thumb or finger)???When you JUMPED out of your seat...and experienced the highest pulse rate of your entire life...you would undoubtedly release all that forward yoke pressure and as a result...on top of whatever other issues you had to face...you would also have to recover from a significant and unintendedly high deck angle...rate of climb and reduction of airspeed.Not a good idea.I enjoyed this dialog.Regards,JimEDIT: Let me also compliment YAWN on reminding us (are you listening Cindy?) that one of the factors influencing the trim setting is the CoG. Therefore, at a given power setting, the trim wheel MUST be placed in a different position, to achieve a target flight condition, depending on whether there is X amount of passanger/baggage weight in the rear of the cabin.

[Guest bobsk8]

Been out of town for a week and I can't believe that this thread and trim disucssion is still going on. I think that much of the discussion on this thread would have been eliminated if the add-on had orginally been titled. "Unreal Trim" ;)

[Guest nilsca]

Hey BobIt's still "Real"Trim in my book ;)I'm not responsible for the pilots discussing flaps/no-flapslandings in here ... eh ... trimming procedures :) CheersNils

[Guest Adverse Yawn]

I would call it "realer trim", it is real one respect but not in the other. The overall effect is that it is more real :)

[Rudi 0]

Cindy I am at KISP. Why.

[Rudi 0]

I said airspeed indicator, attitude indicator and DG (attitude indicator = artificial horizon)

[Guest Adverse Yawn]

Sorry my mistake. Query still stands though, unless the vacum failure is supposed to be a completely seperate and coincidental failure. In VMC the loss of the AI and DG are not an issue. Just look at a Cub :) ASI, though - no thanks, but as my mate's store testifies to too, not necessarily and major problem.

[Guest av84fun]

<>Not really that big a deal either...in VMC. The informed pilot will know what power/flap/gear settings yield given airspeeds for descent, approach and landing.Going through the entire transition from cruise to descent to landing with a covered up AI is taught by wise instructors to their students in primary training.Besides, with even a handheld GPS and an ATIS report, airspeed can be quite accurately calculated anyway.But I would get on the nearest ILS. (-:Regards,Jim

[Guest Cindy_Zoonan]

I had a nearly identical experience. I think the incident to which you are referring happened to me when flying out of KISP.