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C172 sideslip in FU3

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Hi all,Came across this interesting article in Simpilot comparing the FSX and X-Plane flight models of the Cessna 172.http://www.simpilotnet.com/index.php?optio...0&Itemid=32Interesting conclusions, although as the writer observes, to be taken with a large dose of caution.It did set me to thinking about the sideslip authenticity of the FU3 C172 flight model. I have experienced the phenomenon personally, but not while at the controls. After a few seconds of sinking like a stone, my stomach ended up somewhere.. well... up there. :( :( :( Has anyone tried this in FU3? I can't unfortunately as I am forced to used co-ordinated rudder at the moment. B) How does the ten year old FU flight model compare with the other flight model tests?Cheers B) Bruce H

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I took a test flight in our Cessna last night to check various maneuvers and responses. The short answer is that FU III performs like the two others--hardly any effect on sink rate with crossed controls.My recips torque to the left and the force depends on thrust. That's good. To check a sideslipping descent I ended up flying high and then killing the engine to get no torque whatsoever. However, in this situation the aircraft yawed slowly to the right so I had to compensate a bit anyway to go straight. It might be a case of controller calibration or it might be the weather. Evidently, I went for a clear day with no hefty winds but there's probably some air movement anyway.Crossed controls make the aircraft sink faster for a while but when it stabilizes in the new configuration it doesn't seem to make much of a difference. Stalling is pretty much like FS. That is, while you certainly know when you're going too slow the stall is soft and recoverable. Our aircraft may drop a wing but I haven't seen any real spins. It's really strange that the RealAir FS aircraft are capable of spinning since the FS flight model doesn't separate between the two wings. That is, as the model is concerned THE wing is either flying or stalled. RealAir accomplishes this by giving the flight model a very low yaw axis number, actually one that doesn't rhyme with the roll and the pitch numbers. In real life physics these are all interdependent and the yaw value is a function of the other two axes. Weight and balance are also mixed and matched to reach certain goals without worrying about where the various elements really go. It's a "what works works" approach and RealAir does that brilliantly. Critics say that you can't get it right for all the wrong reasons without introducing errors in other flight modes. While X-Plane certainly has the handles to model a proper spin the aircraft may sink too fast during a spin. I'm going to try this out in the latest version of X-Plane. The test used a late version 8 while the current on is at version 9.3. A few important things have happened to the flight model lately.In any event, FU III aircraft still perform well within the normal flight envelope. That's where 95 percent of pilots spend all of their time anyway. While a proper crossed control response would have been nice it's more important that the response to flaps is correct. Proper stall and spin behavior would be very nice to have since it teaches us what to avoid. It's better to have a stall / spin response that's too violent than hardly any at all since stalls kill in real life.

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I did a few more X-Plane tests (v9.3 beta 7). The Cessna is a pretty benign aircraft that won't stall unrecoverably unless you really insist. When you pull up gently to attain 45 - 50 knots the nose comes down and the plane picks up speed again. To make it nasty you have to keep pulling up. Eventually it spins and sinks, apparently sinking too fast. I pulled it out of all spins but I almost hit the ground before being able to resume flight a couple of times.X-Plane may seem to be the best sim in this respect since it does model spins. However, the real Cessna IS a quite stable and benign aircraft and it will take extremely poor piloting skills to go that far. That is, unless we play with loading and put too much weight at the back. To do that in FU III would require us to set up a modified aircraft with more weight and a different center of gravity. While full versus empty fuel tanks will change the weight it can't be used to create a dangerous weight distribution. When real GA aircraft stall an improper weight distribution tends to be a major factor. There's been quite a few bands on tour with too much heavy equipment loaded into the back of a small aircraft.Rounding it off, we shouldn't be too concerned about the FU III Cessna. It's quite a bit too benign when you really try to stall it, the FS Cessna likewise and the X-Plane Cessna probably a bit too wild once it starts spinning. Well, at least it does spin. Anyway, it would be a better idea to compare other aircraft as the Mustang, the Sukhoi and the Beechjet. A fighter, an aerobatic plane and a bizjet should not be too forgiving if you go into a deep stall. The real Mooney has an issue with flat spins -- once it goes into a deep stall it may be very hard to bring back. All flightsims leave something to be desired when you operate way out of the proper flight envelope.

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You might be interested in trying out the Cessna 172SP made by RealAir and uploaded to the Avsim library as freeware. The file name is ras172_fs9.zip, and it is in the Original Aircraft section of the FS 2004 listings. The file description includes this, "This new version will now spin and sideslip in FS2004 ...." Their payware Spitfire model was widely acclaimed for introducing the same capabilities.-Doug

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I tried the Real Air Cessna a long time ago and once more in May. But that was when Avsim "died" so I couldn't post any reply. I can not confirm that sideslipping (crossed controls) increases the sink rate. It does, however, enter a spin if you force a deep stall. Have you tried it out and found that it works as advertised? Real Air stresses that "full realism" is required to make it act as intended.

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No, I haven't tried it myself. I just remembered reading about it and thought it might be of interest to you. For anyone anxious to find it while the Avsim Library is offline, I believe it is available at the RealAir site's Downloads section.It may interest you that Aerosoft is giving quite serious consideration to developing a stand alone replacement simulator to take over where Microsoft has determined not to proceed, and are soliciting input about what the simulator should contain, and what its functions should be. The forum discussion is in the General Discussion sub-forum.The discussion has so far been broken down by month, and has a huge number of posts. The first group, for the month of May, is herehttp://www.forum.aerosoft.com/index.php?showtopic=25954The second June installment begins herehttp://www.forum.aerosoft.com/index.php?showtopic=26062Persons such as yourself are eminently qualified to make serious contributions to these threads. If you read them from start to finish, you'll be amazed at how many people want things that FU3 provided - some of them like weather, they know are FU3 specialties, while others are things they obviously don't know were provided in FU3. In fact, it may be appropriate for someone with your credentials to suggest them buying FU3 code.Well, I certainly went off-topic but I'm grateful to have your attention on the matters discussed.-Doug

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