>>I may be wrong, but prop induced velocity on tail surfaces is>not modeled in FS9.>Off and on, depending on model and variations between FS2002 & FS9, the "spiral" slipstream effect on the vertical stab has been modeled in ranges from a so-so effect, to near perfection.If I can push right rudder on the takeoff roll (clockwise props from cockpit view) and feel like I'm riding a slight rising gutter, without a tendency for pressures to suddenly lighten up which allows for easy weaving back and forth, then I'm happy. And this right rudder force should continue through a good part of the climb phase. Note: forces depends on adjustable rudder trim, fixed rudder trim, etc.It's the prop induced airstream across the horizontal stab/elevator with no to slow airspeeds of the ground roll, that has been reduced in FS9 as compared to some earlier versions. Might be the same with the vertical tail too. I haven't tried bouncing a light tail around lately, by gunning the engine. IMO, it's the rudder force during the takeoff roll & climb, that's most important to get correct, rather than watching visual effects while sitting still on the ground.L.Adamson

>All this talk got me thinking about stuff that I never tried>in FS.>>Tried the prop overspeed last night. CS props don't overspeed>in fine pitch, which they should. But, they don't, at least with power pulled to idle. The prop governor reacts immediately in an overspeed condition and pulls the blades into a coarser pitch to stabilize the rpms. For instance, my Hartzell C/S prop and Lycoming engine has a governor that's set at 2700 maximum rpm at the full forward fine pitch setting. It has adjustable stops. See this:http://www.mccauley.textron.com/prop/prop-...03z-govern.htmlL.Adamson

It is possible I've misunderstood the engineering along the way but my understanding is this:For the Seneca we musn't select fine pitch until on final. The reason being that there is nothing to prevent overrev. Basically, the preload placed on the CSU spring by the prop lever being in full fine position is too much for the fly weights you counteract. Will will therefore be quite easy to windmill the prop into an overspeed. The Seneca uses oil pressure to fine the blade and gas pressure to coursen. So the preload can lock the blades into the fine position (or at least that is my interpretation of my instructors instructions).In a piston single, it is the other way around with a spring to force the prop to fine and oil pressure to coursen so suppose you are correct in that context. Not sure and hard to find info at the moment. Will need to read the flight manual back at the school when visit this weekend.

>All this talk got me thinking about stuff that I never tried>in FS.>>Tried the prop overspeed last night. CS props don't overspeed>in fine pitch, which they should. One can't set prop pitch in MSFS, only RPM. However, it should be possible to get a 'runaway prop' by having the correct prop tables and blade angle limits. I've never had information on such things, so generally make sure the prop 'behaves' up to at least Vne.>Also, I think it is too easy>to get to Vne in stuff like Arrows and C172s. In reality the>drag is so great that from 3000' you would be hard pressed to>get near it before running out of sky. In FS the aircraft just>blat straight to it and beyond. Airframe drag should be pretty close, at least in Prop AC. However, if you mean that it's too easy to hit Vne with the throttle pulled back, that would probably be due to the 'bug' in the windmilling calculation in MSFS. >Also played around and noticed something with regard to>stability. I set an aircraft up at cruise S&L. The dropped to>descent power waited for the a/c stabilise, then increased>back to cruise, waited to stabilise and then climb power and>waited to stablise. I didn't use the yoke at all. You might try just pitching up a bit in cruise, then letting go of the JS, without changing power settings. That would give an 'unaugmented phugoid'. Changing power complicates matters.>Default 172 Timings>Descent = 2:35>Back to Level = 0:50>Climb = 1:00>>DF Arrow>Descent = 2:00 (on a second go it took 5:00!!!???)>Back to Level = 1:20>Climb = 2:05 I took the DF Arrow (I did the FM) up last night and noted there wasn't much phugoid in normal climb, cruise. But I could force one. I developed the DF Arrow FM in FS2K, the loss of prop blast over the stabilator might have changed the above some. Another thing is that FS AC are more highly damped due to the fact there is no 'free stick' effect. The control surfaces do not float, rather they follow the JS' position. It's as if one held the JS fixed all the time in a real AC, rather than letting it float.>Flying Club Warrior>Descent = 2:45>Back to Level = 1:05>Climb = 2:30 Is that a real Warrior?. Your Warrior wasn't that much different from the DF Arrow. Dr. McCormick owns(owned) a PA-28, and gave a lot of technical info on it in his 1996 Aerodynamics Text. He showed the Phugoid period varied with CG; though that isn't normally considered a factor. >Suprisingly the default 172 is the most stable. The Arrow>suddenly went a bit wild on one descent for no reason and took>5 mins to stabilise. I don't think I've seen that. > The Warrior starts with huge fluctuations>which do damp quickly. The Seneca makes the most sense as one>would expect and increase in stability with an increase in>power as there is a greater downforce on the tail then.>They all had the same fault, they all settled at the same>speed (individual for each aircraft) for the three regimes.>This is wrong, the climb should settle at a lower speed and>the descent at a higher one. Somebody mentioned that aircraft>over the tail isn't done very well. I tend to agree. That could be changed. I'm always careful to set the the thrust point accurately, but flow over the windshield, etc. would add some imbalance. I generally set the Horiz Stab at an angle to push the tail down. With there no longer being any prop effect on the tail, that would no longer change pitch trim with power. Now there are tables that change Cm_de and Cm_dtrim wrt Alpha. I think the main reason is so a notch in elevator control can be added when the tail gets into the wing's downwash, which is at a lower speed than free stream speed. I've mainly tried to use those tables in my jet transports. Pitch Trim in MSFS is not realistic. It only changes the pitching moment. It should really have a similar effect to the elevator, which changes the pitching moment and tail lift at the same time.>Another couple of faults. The slipstream effect on the DF>Arrow and Warrior were almost none existant (very slight,>probably just controller calibration!). I also checked the DF Arrow's drag in a slip (again). Yes, it is limited. Cy_Beta appeared to be nominal relative to Cn_beta, possibly the amount of rudder control I set up was a bit too low. I think beta testers had suggested it be reduced from an earlier FM. Note I determined that drag to to Side Force varied with "q*S*CY_Beta*Beta^2" in an earlier version of MSFS. Varying with the square of Slip angle means 20 deg slip results in quite an increase in drag relative to 15 deg slip. At 1/4 radian (14.3 deg) slip, the basic side force should add a relative drag of '45', compared to a zero lift drag of '67'. Which should be noticeable, but not all that much. Also, I need to>re-check, the DF Arrow occasionally seemed to react in the>opposite sense!?! The default 172 seemed to have more.>Regardless, the effect was nothing compared to similar>aircraft in reality. In FS2K one could set sideslip drag with one of the AIR file 1101 parameters, One that was never figured out. That has been dead now for some years. Ron

>Interesting observations. You forget the fuselage side force,>which is roughly proportional to yaw angle, but it actually>adds to engine "side-force". So it doesn't invalidate, but>reinforces your reasoning. The other strange thing is the>ability to fly almost sideways. I wonder in this case how FM>calculates the lift. Maybe a gauge like AFSD could help in>analyzing the forces.You're right. Also, the tail force has a component which contributes to the side-force ..even though it's simultaneously counteracting the yawing tendency, it's still causing the AC to describe a curved path over the ground because it's acting perpendicular to the flight path and is unopposed.It's all these effects that create the disastrous loss of directional control experienced when you lose an engine in a twin.The 'sideways flight' tendency is most pronounced when there is a strong crosswind, as I found out recently after killing the upwind engine shortly after t-off in my DF B58. x(

<>No, the true irony is when some people can't accept the fact that they don't know who is right and who is wrong.<>When does "healty debate" that you seem to so admire, include the use of childish vulgarities?:-)

<>Bob, that surprises me since, in an earlier post in this marathon thread you indicated that as a RW twin pilot, you found that the DF Baron single engine modeling was "amazingly realistic"...or words to that effect.I cannot explain why you "almost fly sideways" on a SE approach to landing in the DF Baron. But I am certain that the issue must be hardware-specific on your rig.No such behavior was encountered in Beta testing across a multitude of different rigs.I just shot a couple SE approaches to be SURE and I experienced no such behavior EXCEPT when excessive power was carried on the good engine.<

<>You are too funny Rico. Bob has actually...repeatedly...offered the opinion that the Baron FDE is surprisingly accurate but you started this thread with the premise that the Baron flight model was: <>If you now concur...100%...with Bob's obviously skillful analysis, then you contradict the very premise of your original post.But that sort of "flip flopping" is nothing new. In another thread in which you found the need to demean DF's flight modeling, you incorrectly posted that in a slip, both rate of descent and airspeed are supposed in increase.After you were corrected on that subject, you posted in this thread...<>While it is good that you eventually reversed your error on airspeed dynamics in a slip, the balance of your above post remains incorrect. The DF Baron does not "float or gain altitude" in the slip unless..A. Your flight control rig is defective orB. YOU are adding back pressure on the yoke when attempting only to activate the ailerons.Regards,Jim

>I cannot explain why you "almost fly sideways" on a SE>approach to landing in the DF Baron. But I am certain that the>issue must be hardware-specific on your rig.I experienced the same behaviour.>I just shot a couple SE approaches to be SURE and I>experienced no such behavior EXCEPT when excessive power was>carried on the good engine.Uhm, but IMHO excessive power as well, would not allow the a/c to fly almost sideways (in RL).>You stated that "the component of thrust from the operating>engine acting perpendicular to the flight path...">But thrust from the good engine does not operate>"perpendicular" (i.e. at 90 degrees) to the flight path. It>operates at a tangent to the flight path.He didn't mean that the thrust from the engine operates perpendicular to the flight path, but that the thrust _has_ a component that acts perpendicularly to the flight path.P.S. we need another 24 posts to break the record:http://forums.avsim.net/dcboard.php?az=sho...ing_type=search

>Well, I haven't seen MSFS with any FAA certifications for>flight training, irregardless of $125,000 coupled simulators. >:) I was mostly trying to point out the role in which the US>Navy was using MSFS, as I believe the original poster of this>particular subject misunderstood such.>Maybe MS wants nothing to do with FAA certification? Remember when the unfortunate events of 9-11 not only delayed FS2002 but there were some rumblings that it may have been cancelled? Of course all of that was (I think anyhow) RUMORS. Maybe MS doesn't want to go anywhere close to having a lawsuit slapped on them. Gosh knows they have enough people after them looking for loopholes into B. Gates wallet already!

<> I do not pretend to be an aerodynamicist and Bob could be correct with respect to jet engines but not with prop engines for the following reason gleaned from a major university's aerodynamic program.",The forces. Propeller blades are constructed using aerofoil sections to produce an aerodynamic force, in a similar manner to a wing. Consequently the blades are subject to the same aerodynamics

<Right Tom.Having flown an X-plane based MOTUS sim, driven by no less than six servers, I can assure you that there is no practical reason why a similar system based on FS9 could not obtain certification if FS cared about that...which they apparently do not.Rico posted:<<>Well, I haven't seen MSFS with any FAA certifications for>flight training, irregardless of $125,000 coupled simulators. >:) I was mostly trying to point out the role in which the US>Navy was using MSFS, as I believe the original poster of this>particular subject misunderstood such.>>But as was pointed out elsewhere in this thread, it is Rico who misundersands the role in which the Navy and MANY top flight schools are using FS9.Regards,Jim

Jim,Are YOU a R/W multiengine-rated pilot?

Personally I think creating a loggable sim from FS would be a touch nut to crack. Although I doubt FS would have much if anything to do with the process. It would be a third party who would have to package up the sim as a collection of hardware, aircraft modeling (physical and visual), instruments, controls, enclosure, visuals, instructor station etc. In this context It is easy to underestimate the amount of work required to accomplish such a feat. Just as an example of some of the current characteristics that make it extremely difficult to produce anything like half decent results for a trainer:1) Instruments are very flakey. It simply isn't possible to practice realistic unusal attitude recovery.2) Fluidity of instruments, especially the HSI/DI is an issue. It is possible to use something like Reality XP, but I have been told there are issues with the turn coordinator realism.3) Consistency of cloud bases. It must be possible for the instructor to set a cloud base that he knows prevents visual contact before DA/MDA on an instrument approach. With FS as it is, for all he knows the student found one of the many holes in the 'overcast'.4) Loading situations/scenarios. If you load a scenario, the a/c must be instantly flyable, not take time for engines to spool up, do a bit of a nose down, etc.5) ATIS voice over VORs. As far as I know this isn't possible.6) Framerate consistency. It is usually all over the shop.7) Instructor station. The instructor must be able to manipulate the aircraft and environement in whatever way he wants (increase alt, low cloud base, move aircraft). This needs to be quick with consistent results and instant resume. Not something available within FS at the moment.8) Flying by numbers. It is no good having an FM that is nearly right. It must be spot on or else how can a student be expect to fly with precision in the real aircraft. The current pressing bubbles in wallpaper FM, where solving one problem creates another, is not upto it.9) Failures: They aren't comprehensive enough. It isn't really possible to create subtle problems that would lead to failure if unchecked such as a creeping CHT.10) Asymetrics and Vmc: Its no good arguing about it. They are goofed in FS. Some serious research is needed to get around that problem.Sim time is logged against the hardware and charged by the hour an no student will be pleased if it is another case of "lets try that again".To solve all those issues requires a massive amount of custom code and hence alot of upfront cost and considerable financial risk. I simply don't believe the development costs would be justified by the potential revenue. It's not going to happen in my opinion because for an FS based sim to stand a chance it needs to be cheaper by the hour, not more expensive that the established competition.From the official FS site:"The Navy's T-34C Turbo Mentor training plane will be imported into the product so students can train for their first flights." "First Flights" That say it all. Basically, this is the stick and if you move it left....you get the my drift I think.

[CUT]>So, there is no perpendicular "thrust force" but rather a>"torque force".I think there's a simple misunderstanding.Since a picture is worth a thousand words, I enclosed one to figure the situation described by Bob. (I left out all drag forces that are by definition parallel to relative wind). What Bob was trying to point out is that an a/c's can't fly along a straight path, while the nose is yawed away from the operating engine and (at the same time) with wings level, since in this case there is not any force to oppose the component of thrust acting perpendicular to relative wind (rudder/vert stabilizer sideforce in this case has the same direction, so it adds up).>More importantly, however, no matter what the force acting>perpendicular to the longitudinal axis might be called, just>as is true in wind triangle calculations, the components>become less and less significant...to the point of being>irrelevant.True, it's small, but increases quite rapidly even for small angles. For example, it becomes 10% of total thrust for only 6 degrees yaw angle, and 20% for 12 degrees yaw angle.Bob reasoning is correct, but it should be carefully verified with flight tests within FS.Marco