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michal

Cessna 172-Stays in Turn Except For RealAir??

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The issue is the Cessna staying in a turn or rotating out on its own. The FSX and FS9 stock Cessnas and the FSX Carenado Cessna 172 all seem to stay in the turn position/attitude when the yoke is returned to its neutral position. However, in FS9 the free-ware RealAir 172 returns to a level wings attitude over time when the yoke is returned to its center neutral position. Quite different Behavior. Which is correct?Regards,Dick BoleyA PC, an LCD, speakers, CH yoke

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The way I recall from my 172 flying days the actual behaviour is quite complex. Depending how shallow/steep the bank angle is the aircraft will either eventually return to wing-level position or it will keep titghtening the turn. How symmetrically it is loaded, whether pilot is the only person may also have big influence on the outcome. I never recall making turns with not less than 30 deg bank and aircraft having tendency to return to wing-level on her own, never.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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On numerous occasions when flying different aircraft, I have a tendency to move the yoke or stick from side to side, as well as the rudder pedals, just to compare to the sim world.If I should swing the Cessna's yoke to the left and release, but not make a real attempt to initiate a turn, the plane will bank, and then swing back to neutral. With the Van's RV's, the plane will just sit at the same banked angle for a period of time. I just haven't waited to see how long it will stay banked.All in all, with so many planes behaving differently, I don't get to upset if the sim plane doesn't model the exact actions perfectly.BTW, other differences--- make a banking turn in a Cessna 172, and be prepared to pull back on the yoke to keep altitude. With an RV, you don't pull back, and possibly might have to push forward. The Cessna pitches up with flap deployment, and the RV pitches down! The Cessna needs rudder in the turn to stay coordinated, and the RV usually doesn't :-hahL.Adamson

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Reggie,I cannot afford the extra $100 for the new USB pedals. Unfortunately my old gameport are now useless. I don't believe that their is a rudder trim available on the 172 in the aircraft I mentioned. The elevator trim was at level flight. I did use the yoke/elevator to maintain level flight in all cases.Regards,Dick BoleyA PC, an LCD, speakers, CH yoke

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This site has the following explanation of the function mentioned by Rob Young:http://selair.selkirk.bc.ca/aerodynamics1/...lity/Page5.html=======================================Lateral stability refers to stability around the longitudinal axis. It is sometimes called roll stability, although this is a misnomer.Rolling Moments and Roll DampingWhen the aircraft is flying in straight flight (no slip) with the ailerons neutral both wings produce the same amount of lift. This is true because both wings are at the same angle of attack and flying at the same velocity.If the pilot deflects the ailerons then one wing will produce more lift than the other (because it now has more camber.) This causes a rolling moment. The aircraft will begin to roll and will continue to roll, faster and faster, as long as one wing produces more lift than the other. As the aircraft rolls the angle of attack of the down going wing increases and the angle of attack of the up-going wing decreases. Before long the lift difference between the wings will disappear. Once the lift from both wings is the same a constant rate of roll will be established (the more the ailerons are deflected the higher the roll rate will be.) If the pilot returns the ailerons to neutral there will once again be a difference in lift between the wings with the down going wing being at a greater angle of attack. This condition will cause a roll rate in the opposite direction until the roll stops. At that point both wings are producing the same amount of lift and the angle of bank will remain constant.Lateral StabilityMost light aircraft display approximately neutral lateral static stability. In other words when rolled into a given bank and released the aircraft remains more or less at that angle of bank.If the aircraft rolled back to zero bank by itself we would say it had positive static lateral stability. If it rolled further, into a steeper bank we would say it was displaying negative static lateral stability.Most light aircraft if left with no pilot input will eventually roll into a steeper turn, usually entering a spiral dive. This means that most aircraft exhibit negative dynamic lateral stability. Despite this they can be flown quite well, except they require considerable attention when flying in IMC conditions.As indicated above lateral stability and directional stability are closely linked. If an aircraft has a lot of directional stability (most do) it tends to become unstable laterally. This is because the bank angle starts the aircraft turning, which speeds up the wing on the outside of the turn (high wing.) The faster wing produces more lift, which rolls the aircraft into a steeper bank.All aircraft will exhibit negative lateral static stability, as describe above, unless the designer adds some combination of the design features listed below to combat the effect described above. Dihedral High Wings Swept Wings=================================================The explanation makes sense but which Cessna is correct. Does a real Cessna have positive or negative lateral stability?Regards,Dick BoleyA PC, an LCD, speakers, CH yoke

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Hi Dicknot much experience with a real c172 here, but from what I know, the c172 is built as a very stable aircraft and will return to straight level flight over time if you let go of the controls - even from more extreme attitudes. The RealAir models this very well. When it comes to flight dynamics, in case of doubt, I'd trust what Rob has come up with.Cheers,Christian

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>The issue is the Cessna staying in a turn or rotating out on>its own. The FSX and FS9 stock Cessnas and the FSX Carenado>Cessna 172 all seem to stay in the turn position/attitude when>the yoke is returned to its neutral position. However, in FS9>the free-ware RealAir 172 returns to a level wings attitude>over time when the yoke is returned to its center neutral>position. Quite different Behavior. Which is correct?>>Regards,>Dick Boley>>A PC, an LCD, speakers, CH yokeThe 172 has positive stability in the real world, it will eventually return to wings level if the controls are neutral (unless you are in an extreme bank angle, then the bank angle may increase further). The FSX model isn't accurate in this regard.

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> The 172 has positive stability in the real world, it will eventually return to wings level if the controls are neutral (unless you are in an extreme bank angle, then the bank angle may increase further). I beg to disagree, my actual 172 flight experience simply contradicts that.In my opinion what you call "extreme" is in fact something much closer to say around 45 deg or even less. The aircraft will never return to wings-level from such steep bank on its own, not at least per my experience having flown 172 about 270 hrs.As a matter of fact in this fairly respected source: http://www.av8n.com/how/htm/roll.htmla quote: "in a coordinated turn, the aircraft is happy to continue turning forever; it will definitely not have any tendency to return to wings-level flight. Indeed, it will have the opposite tendency, called the overbanking tendency which we now discuss ..." I recommend to read it in depth.If I recall Flight1's C172 had this overbanking tendency modeled pretty well though it was long time ago and I no longer have it installed so I can't easily check.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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The 172 stays in a turn once you enter a turn and center the yoke. It will eventually, but very, very slowly return to level flight depending on your rudder input/adjustment and depending on the winds aloft.For vertical adjustments to the elevator, it is true that it will return to level flight when the controls remain centered, but it is only partially true for lateral adjustments.Pat

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Thanks for finding that article Dick.I do believe the high wing design was chosen by Cessna (in their attempt to create the "Car in the air" to make as stable a platform as possible, with positive roll stability (as Rob notes).OT - There's a cool Cessna ad from the 40's on the walls at Daniel Webster College stating how after the war, people flying Cessna's to the grandparents for Christmas will be a common thing.Thomas[a href=http://www.flyingscool.com] http://www.flyingscool.com/images/Signature.jpg [/a]I like using VC's :-)N15802 KASH '73 Piper Cherokee Challenger 180

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>The issue I'm having is if the wings are banked>even as little as 2 or 3 degrees in flight sim,Two completely different things. Roll stability is there to make sure the airplane will return to wings level in such cases. What we are talking here about is return of the 172 from a pronounced, coordinated turn to wings-level. This does not happen in real world. And your comment about "descent rate" also is not very relevant to the subject. If you ever flew real Cessna with an instructor when steep turns are practiced it is not a big deal to trim the 172 that the airplane will be both turning and not losing altitude, even with 45 or 60 deg bank, all skilled pilots can do it well. I also go on record to state that return to wings-level doesn't happen in a typical standard turn like 30 deg bank.Michael J.http://img142.imageshack.us/img142/9320/apollo17vf7.jpg

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>> The 172 has positive stability in the real world, it will>eventually return to wings level if the controls are neutral>(unless you are in an extreme bank angle, then the bank angle>may increase further). >>I beg to disagree, my actual 172 flight experience simply>contradicts that.>>In my opinion what you call "extreme" is in fact something>much closer to say around 45 deg or even less. The aircraft>will never return to wings-level from such steep bank on its>own, not at least per my experience having flown 172 about 270>hrs.>Well, I've never actually put the 172 in a 45 degree bank and let go of the controls to see if it would recover, the descent rate would be the only thing you'd worry about in that situation. The issue I'm having is if the wings are banked even as little as 2 or 3 degrees in flight sim, the 172 will never return to wings level, in the real world it would rather quickly, and I have tested that.

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Dick, I'm guessing you have Rudder Pedals that have a gameport connection. If so you can still use them. I'm using gameport Rudder Pedals I've had for years. All you need is a gameport to USB converter. If you Google it you will find a wide variety of makes and prices. I picked one up online for approx. $25.00 US. Can't remember where I got it though. Craig

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Sorry to chime in, but how do you define "neutral controls"? Surely if you trim your aircraft it's not neutral anymore (ie trim = elevator deviation)?Christian

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First let me make a correction = the Cessna I used was not Carenado but Flight-1.According to what I am seeing none of the aircraft in FS9 or X do a perfect job at this task. Now is the time for the usual reminder - "what do you expect for $70". For moderate turns of 30 degrees or less the RealAir 172 seems to have it right and it returns to wings level over time. Assume all trims are for level flight and no wind. Once you exceed some amount of banking a point is reached where either the aircraft seems to hold that point or the bank becomes more severe resulting in a possible spin.IF the Cessna 172 is designed with positive lateral buoyancy then the 172 should always return to wings level with a "reasonable" amount of bank. Those models at moderate banking that stay in bank despite the centering of the yoke appear to be faulty. I suspect that very severe banking may give unpredictable results in terms of detailed incremental actions. You can probably count on a spin at the extremes.Regards,Dick BoleyA PC, an LCD, speakers, CH yoke

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>First let me make a correction = the Cessna I used was not>Carenado but Flight-1.Flight1 Cessna 172 is the best Skyhawk I ever tried in MSFS.>seems>to have it right and it returns to wings level over time.Your opinion. I stated many times (I have about 270 hrs in real 172) that this is not to be expected in a real aircraft, any aircraft, not only the 172. I suggest you read some textbook on aerodynamics (I have provided a good link on roll stability above) that will enlighten you on the subject of positive lateral buoyancy?. But you can definitely pick an aircraft that works best for you.Michael J.

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>If you ever flew real Cessna with an instructor when steep turns>are practiced it is not a big deal to trim the 172 that the>airplane will be both turning and not losing altitude, even>with 45 or 60 deg bank, all skilled pilots can do it well. I have plenty of time in a real cessna (I'm just a few hours away from my instrument checkride and all my training was done in 172's). If any instructor ever lets you trim an airplane for level flight while in a steep turn, find a new instructor. Think about it, as soon as you roll out of the turn, the nose of the airplane will point upward (think about the 60 degree, 2g rule, when you return to zero degrees of bank, you only need about half the lift, but you are trimmed for twice that).

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>Your opinion. I stated many times (I have about 270 hrs in>real 172) that this is not to be expected in a real aircraft,>any aircraft, not only the 172. I suggest you read some>textbook on aerodynamics (I have provided a good link on roll>stability above) that will enlighten you on the subject of>positive lateral buoyancy?. >>But you can definitely pick an aircraft that works best for>you.>>Michael J.Your posts in this thread stink of arrogance. http://sio.midco.net/FTP5/thumbdown.gif

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It has been a long time since I flew a Cessna-but plenty of intructors in my area that use Cessna 172's advocate trimming the plane in a steep turn for "hands off" flying of the procedure.Trim reduces control forces. If one trims while in the steep turn there will be less work involved- then rolling out of the steep turn-one will have to point the nose downward and of course retrim to reduce the forces-of course if one didn't touch the controls to pitch to correct attitude and didn't retrim perhaps your scenerio would happen-but who in their right mind would not re-adjust? In a similar vein-doesn't the same happen in a go around? One will have to apply power and point the nose in the right direction at the go around point -and of course retrim from the landing position-the control forces may be considerable at that point but to do otherwise would be a problem.http://mywebpages.comcast.net/geofa/pages/rxp-pilot.jpgForum Moderatorhttp://geofageofa.spaces.live.com/

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> Think about it, as soon as you roll out of the turn, the nose>of the airplane will point upward (think about the 60 degree,>2g rule, when you return to zero degrees of bank, you only>need about half the lift, but you are trimmed for twice>that).I never trimmed for a 60 deg bank but certainly trimmed for a 45 deg bank. Not a big deal if you know how to fly the airplane and how to overpower controls if necessary. The forces are reasonable and transition from steep turn to wings level can be spread over some time to allow more time to re-trim. Again, for a pilot who knows how to handle airplane and anticipate things - not a big deal, there are certainly more challenging maneuvers in aviation.Michael J.

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