> Most is done intuitively, even though most pilots>(etc.) can't explain exactly what they are doing. I'd say much quite like aero engineers: if you ask 10 of them why airplanes fly, you get 10 different responses (and probably a flame war on Bernoulli, Newton, circulation and Lift Demons), nevertheless their brainchilds fly (most of the time). :DMarco

(in spite of Big Al's distaste for summing>up..you really should stop acting like a little kid who just got told no from his parents>not a Cub Scout Pack.and yet here you are, the only person in the topic with childish replies since your first one.

>> Most is done intuitively, even though most pilots>>(etc.) can't explain exactly what they are doing. >>I'd say much quite like aero engineers: if you ask 10 of them>why airplanes fly, you get 10 different responses (and>probably a flame war on Bernoulli, Newton, circulation and>Lift Demons), nevertheless their brainchilds fly (most of the>time). :D>Marco I bet you noted 'Lift Demons' in sci.aeronautics. ;) Looks like you are now looking for 'flow over swept wings'. As far as lift goes, I'm sure it's either Navior-Stokes or Lift Demons. The later appears more often, so is probably correct. Those little devils multiply like crazy in the transonic range. At hypersonic speeds most are swept away or burned up. Are you modeling a Barron in X-Plane? That's what the flow images from X-Plane appeared to apply to at your site. However, it's not clear there is any prop wash over the wing. BTW, if you are interested in a few ideas applying to modeling swept wings in MSFS, email me. Ron

Ron,>>Most is done intuitively, even though most pilots (etc.) can't explain >>exactly what they are doing. As you say. Indeed the Human Performance and Limitation section of our ATPL course covered alot of these aspects. Some psychologists explain a skills development in phasesstages: Cognative , Associative and Autonomous. The latter stage being the phenomenon you describe; where motor and cognative skills are fully integrated. As classic example of this is the power for height and stick for speed technique that is taught by most schools. Most experienced pilots will tell you that they combine the two natuarally and instinctively...i.e. the just fly and land :)On a total TANGENT and on the latter subject, one school in the UK has abandoned the power for height/stick for speed technique in favour of a more point and shoot. They claim that it took too long for students longer to stabalise the approach. Frankly I can't help but think they've missed the point of that instructional method with regard to the general interplay between controls. In addition they use Grumman AA5s as trainers, a most unsuitable aircraft in my opinion as they can take quite alot of management, absolutely have to be landed on the mains (no room for error), low prop clearance and supceptible to PIOs (relatively speaking in relation to 152s, 172s, PA28s, etc). I really wish somebody would do one for FS.

> As far as lift goes, I'm sure it's either Navior-Stokes or>Lift Demons. The later appears more often, so is probably>correct.Eheheheh...> Are you modeling a Baron in X-Plane? No, I am not the author of that model, I prefer airliners and aerobatics a/c's, but I'm just beginning to experiment some plane-making.> That's what the flow>images from X-Plane appeared to apply to at your site. >However, it's not clear there is any prop wash over the wing.I think longer lift vectors behind the prop are the effect of propwash. In past versions of X-P there was the possibility to show also the swirling flow the prop left behind. It was really neat to see, but the author removed that possibility!> BTW, if you are interested in a few ideas applying to>modeling swept wings in MSFS, email me. Ok :)Marco

>Ron,>>>>Most is done intuitively, even though most pilots (etc.)>can't explain exactly what they are doing. >As you say. Indeed the Human Performance and Limitation>section of our ATPL course covered alot of these aspects. Some>psychologists explain a skills development in phasesstages:>Cognative , Associative and Autonomous. The latter stage>being the phenomenon you describe; where motor and cognative>skills are fully integrated. I often had to think about a slip with crosswind; I didn't do them all that often. Though the control of each of four axis was more intuitive. OTOH, it wasn't clear I twisted the handlebars on a motorcycle just the opposite direction I wanted to turn until I analysed it. We learn to control our bodies and cognitions as infants; no one needs to think about how to walk unless he has suffered an impairment. In fact, walking is very complex, and no one knows exactly how the brain develops the motor control required. I bet young kids could learn to fly quite easily. But, it had better be in a simulator. One mistake and he probably wouldn't get another chance in a real AC.>As classic example of this is the>power for height and stick for speed technique that is taught>by most schools. Most experienced pilots will tell you that>they combine the two natuarally and instinctively...i.e. the>just fly and land :) I spent a lot of flying an RQ-1 Predator in FS with a full screen view, HUD (experimental). I carefully used the throttle to climb, cruise, and descend. IAS stayed nearly constant. But only if I damped out the Phugoid manually at lower speeds. It's that Phugoid oscillation which can make it difficult to see how well that works. The same applies to jet transports, one has to get the trim right to climb at the correct IAS, while controlling vertical rate with the throttle.>On a total TANGENT and on the latter subject, one school in>the UK has abandoned the power for height/stick for speed>technique in favour of a more point and shoot. They claim that>it took too long for students longer to stabalise the>approach. Yes, that Phugoid again. That RQ-1 HUD above also has a flight path indicator which makes it easier to 'point and shoot'. Also, an AoA scale right near the center of the view. I linked another cursor in the XML code to indicate when thrust was equal to drag. Use the throttle to set that point and the AC would eventually fly level at current IAS and throttle setting. A lot of "cheats", but useful to see what is really going on. OTOH, the full screen view is just the opposite, it gives a good view for landing with no panel in the way. Which is a major problem with most all PC simulators. > Frankly I can't help but think they've missed the>point of that instructional method with regard to the general>interplay between controls. Seems learning how power controls VS would be the first thing to teach. Then, work in the 'point and shoot' landings, but don't forget the former. I remember how 'Stick and Rudder' claimed one could land shorter by slowing down the AC. But that results in first flying level for a while to kill speed. It appears one is going to contact the runway farther away. But, wait a while, with the lower approach speed it takes longer to reach the threshold, even though vertical speed may not drop significantly. I found it did work. That only works if one isn't too fast in the first place. I tended to use brute force to get a PA-28 down, sometimes using full flaps and some slip. Something that gives an immediate effect! One can experiment with the above in FS. Slips don't appear to add all the drag they should, but do add some. Ron

Ron,>>I carefully used the throttle to climb, cruise, and descend. IAS >>stayed nearly constant. But only if I damped out the Phugoid manually >>at lower speeds. It's that Phugoid oscillation which can make it difficult to see how well that works. The same applies to jet >>transports, one has to get the trim right to climb at the correct >>IAS, while controlling vertical rate with the throttle.I'm not sure what else you have flown so maybe you don't readily identify with this, but this is certainly something I noticed any aircraft to a degree and is quite pronounced in even slightly more powerful aircraft like the Arrow turbo and Seneca (the biggest I've got to fly). If you trim for straight and level, reducing power seems to reduce the elevator downforce significantly (i.e. more noticably). The results in an a greater than commensurate pitch down and an increase in speed meaning much more up trim is required than to maintain speed and RoD. The most reliable way to stabalise the descent (for low-houred at least pilots like me) in these aircraft is to reduce power when straight and level to the target speed and then drop the nose to achieve the RoD. Whereas with the PA28s, AA5s, et al it seems to be easier to to just reduce IAS and tweak. A jet, because of the lack of slipstream, should not have these characteristics...in theory at least...I think.I can't say I've taken a great deal of notice when applying climb power rather than reducing, that is assumed to be a case where a retrim is required because even cruise climb speed on the aircraft I've flown as slower than cruise. Although there is a Catalina share going at Duxford, 1/20th for

>> That only works if one isn't too fast in the first place. >I tended to use brute force to get a PA-28 down, sometimes>using full flaps and some slip. Something that gives an>immediate effect!>> One can experiment with the above in FS. Slips don't appear>to add all the drag they should, but do add some. >A particular "flight dynamic" that needs much farther improvement, is the ability to slow down (good air braking effect), when pushing the "constant speed" prop control full forward for fine pitch and high drag; for entering the pattern, or a high altitude "carrier approach".Last year, a friend and I, made it a point to see what we could do with a new Van's RV9A, 0-320, and Hartzell C/S prop. We did "drop like a rock carrier landings", landing with the wind, and everything in between, just to see what kind of short field performance was possible in varying conditions. The C/S prop, makes all the difference in the ability to slow down quickly versus the fixed pitch. Pushing the blue knob forward in FS, never seems to have enough of the desired effect. And BTW, this subject was brought up in the RV forums, using Flight Factory simulated RV as an example. Just something else to play with, in the arena of flight dynamic design... :D L.Adamson

>Ron,>>>I carefully used the throttle to climb, cruise, and descend.>IAS >>>stayed nearly constant. But only if I damped out the Phugoid>manually >>>at lower speeds. It's that Phugoid oscillation which can>make it difficult to see how well that works. The same applies>to jet >>>transports, one has to get the trim right to climb at the>>correct IAS, while controlling vertical rate with the throttle.>I'm not sure what else you have flown .. Very few real AC.> so maybe you don't>readily identify with this, but this is certainly something I>noticed any aircraft to a degree and is quite pronounced in>even slightly more powerful aircraft like the Arrow turbo and>Seneca (the biggest I've got to fly). If you trim for straight>and level, reducing power seems to reduce the elevator>downforce significantly (i.e. more noticably). The results in>an a greater than commensurate pitch down and an increase in>speed meaning much more up trim is required than to maintain>speed and RoD. The most reliable way to stabalise the descent>(for low-houred at least pilots like me) in these aircraft is>to reduce power when straight and level to the target speed>and then drop the nose to achieve the RoD. Air flow over the tail and how wing downwash is changed by the prop certainly affects pitching moment. Thrust offset from the vertical waterline also makes a difference. Regardless, if one doesn't change the power too rapidly, the final descent IAS may not change that much. As one gets familiar with a specific AC he can use the yoke, then trim, to pitch the AC to the steady descent slope. > Whereas with the>PA28s, AA5s, et al it seems to be easier to to just reduce IAS>and tweak. A jet, because of the lack of slipstream, should>not have these characteristics...in theory at least...I>think. Generally jet transports do have a vertical thrust offset. Which is due to both the distance from the vertical CG and the turbines angular offset. It is usually desirable to have the nose pitch down with increased thrust. That is what one wants if he adds a lot of throttle when near a stall. Pitch down also helps keep the AC from pitching up too much when one wants to increase ascent rate. That sounds backwards, but I think it helps minimize a Phugoid.>But I've not experianced an aricraft that has gone through the>oscillation (phugoid in your posh words :)) that many FS>aircraft seem to exhibit when adjusting power. Could be due to incorrect thrust point. Or, the fact there is no longer any prop wash. And, when there was, I don't know if it had the appropriate effect on the tail, since FS 'elevator trim' does not emulate a trim tab. If it did, it might have responded to prop wash. Supposedly the Phugoid period depends only on TAS. I found it was typically 97 seconds for a 747, and that's near what I measured for my FS 747. The period was also right for a 172. However, how fast the Phugoid damps out appears to depend on Lift/Drag. I noted it didn't die out very fast in the Predator I modeled. Finally I realized I was climbing at 'best endurance' IAS, where L/D is about twice that of a 172. The oscillation did die out faster at higher speeds, where L/D dropped. The majority of FS jets have excessive drag, also very high pitch damping (10X real). The high drag would help damp the Phugoid, but I've noted high pitch damping seems to result in way too slow a pitch change, and that makes them harder to trim. >>> I remember how 'Stick and Rudder' claimed one could land shorter >>>by slowing down the AC. ...>Stick and Rudder's section on the glide is pure gold.>>>One can experiment with the above in FS. Slips don't appear>to add all the drag they should, but do add some. >Funny you mention that. I knocked up a wee video of an FS>Seneca sideslip here: http://www.bishbashbosh.org/index.htm It>won't be there for long though. However, you will see it>creates a alot of drag - and no, I wouldn't do that in real>life unless I very desperate indeed (assuming I could of>course)! I'm afraid a video would take forever to DL at 44.0. ;) Ron

>>>> That only works if one isn't too fast in the first place.>> One can experiment with the above in FS. Slips don't appear>>to add all the drag they should, but do add some. >>>>A particular "flight dynamic" that needs much farther>improvement, is the ability to slow down (good air braking>effect), when pushing the "constant speed" prop control full>forward for fine pitch and high drag; for entering the>pattern, or a high altitude "carrier approach". I've worked on the prop tables in twins to get more windmilling drag with power off, but didn't much consider higher prop drag at idle throttle. Without cutting the ignition or mixture I always saw some thrust from the prop.>Last year, a friend and I, made it a point to see what we>could do with a new Van's RV9A, 0-320, and Hartzell C/S prop.>We did "drop like a rock carrier landings", landing with the>wind, and everything in between, just to see what kind of>short field performance was possible in varying conditions.>The C/S prop, makes all the difference in the ability to slow>down quickly versus the fixed pitch. I did do what I could in a C208B turboprop to increase prop drag when the throttle is pulled back; especially with the Condition Lever in Low. Though, I don't think I got it as high as in the real 208B. >Pushing the blue knob forward in FS, never seems to have>enough of the desired effect. And BTW, this subject was>brought up in the RV forums, using Flight Factory simulated RV>as an example. >Just something else to play with, in the arena of flight>dynamic design... :D >L.Adamson I did the FFS RV-7. I just checked and see I didn't play the trick in the prop efficiency table I do in twins to increase windmilling drag (at least with a dead engine). I don't remember anyone bringing it up before for an SEL. I'll try to remember your comment! There is a bug in the FS SIM1.DLL that results in windmilling drag not being accounted for properly. I suspect that could be fixed by adding one line in the source code. But, getting MS to fix such things is just about impossible. They knew about the excessive rolling drag before FS9 came out, but left it as it was. It finally took a guy in Germany to find the rolling drag tables and fix a few entries with a hex editor in sim1.dll. It does seem that the engine/prop should add drag if the RPM is higher than Idle RPM. OTOH, if one manages to stop FP prop rotation with the ignition cut, the prop drag actually decreases. I heard a C172 will glide farther with rotation stopped then with the prop windmilling. One should also drop glide IAS from about 70 kts to 62 kts. I have observed that in my C172 flight model. I couldn't get that RV-7 to spin decently without messing up the normal flight dynamics. However, I had an EAA data report on the AC with lots of digitized performance data. And, found my FM was remarkably close. Ron

> I couldn't get that RV-7 to spin decently without messing>up the normal flight dynamics. However, I had an EAA data>report on the AC with lots of digitized performance data. >And, found my FM was remarkably close. >Yes, the flight model is really close. A good representation of the "feel" of flying an RV. I used it a lot, but the VC panel is a bit dated these days.I remembered that you had done the FM, which is why I brought it up. :D L.Adamson

Ironic, isn't it? Some people just can't accept when they know someone else is right. He's just upset that he's been called on for being a bit of a prat.There's a difference between 'healthy debate' and 'being a butthole.' Figure it out. And while you're at it, learn to not take the internet so seriously, before you have a heart attack (or you go overboard and get banned, it doesn't make much difference to most people, really).

But Paul, yours can't be more realistic than mine, mine was developed using the googleplex quotient. Surely you're aware of the googleplex quotient? ;)

> Generally jet transports do have a vertical thrust offset.>Which is due to both the distance from the vertical CG and the>turbines angular offset. It is usually desirable to have the>nose pitch down with increased thrust.But in airliners with wing mounted engines, the position of these latter should generally produce a nose pitch up, right?Marco

Marco,>>But in airliners with wing mounted engines, the position of these >>latter should generally produce a nose pitch up, right?I wansn't really commenting on the instantaneous reaction to the application or removal of power, more the general sustained effect. However, yes, to what degree I'm not sure but buy most accounts it is pretty insignificant in a most operational situations (low moment, spool times, etc probably come into play). I guess :)