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Guest jcomm

Prop effects in FU3...

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I recall from the old days of FU2 that slipstream effects, but also torque, were considerably more effective than in fu3.In fu3 most of the aircraft, standard or add-on, show praticaly no yaw tendency during takeoff and initial climb, and rudder, unless a crosswind is present, is normaly not required, something that is, IMHO, one of he major limitations/absences in fu3 FM.The Mooney is a good example of this. The real aircraft (and also the model in fu3) has a rudder trim position for takeoff & initial climb, but Mooney pilots still have to add right rudder to counter the slipstream effect during takeoff. In fu3, even if we enable (as I allways do...) torque, this effect is almost inexistent.Yet, the "Red Baron" is very sensible to abrupt power inputs during takeoff, and also appears to react to slipstream effects in a rather convincing way, which contributes to leaving me very confuse about this subject...After all: Can someone tell me if realistic prop effects can be modelled in fu3 after all?

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J.C.,It does work - for me at least. Tried the GeeBee R2 with torque switched on? Give it full stick on the runway and it almost flips over :-eek Actually had trouble with that one - trying to get little enough torque to make others happy. Me? I just use full aileron as well :-lolRegards,**************Jonathan Point**************"I'd rather be down here wishing I was up there than up there wishing I was down here"

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Jonathan,OK, you're describing torque, wich is almost unnoticeable over the great majority of GA prop aircraft, and indeed I think fu3 models it, but, what accounts for the need for rudder (right or left depending on CW or CCW rotating prop...) during takeoff and initial climb is mainly slipstream effect, or the "hellical" effect of the propwash over the horizontal tail.It's been a long time since I last digged into the details of fu3 "AIR" files but I recall some parameter, associated with an object, that somehow indicated if it was on the propwash(???). Maybe it got nill in fu3, but it surely played it's effects in fu2!!! As a matter of fact, in fu2 it was well kniwn for playing the effects in the the reverse sense (requiring left rudder where right rudder was supposed to be used, etc...).

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Hi guys,you need to add a line to your flt3.cfg filelike so; 1 for 'on' and 0 for 'off'. Its' originally a line from FUII config but works in FUIIIopt_jet_wash 1:-wavePete

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Thx Pete for the hint!I will try it later tonight, and will let you know the results ASAP!!!Sometimes those "hiden" parameters pretty much remind me of Fly2!, another great sim - again light-years away from MSFSish thingy... - lost for stupid commercial reasons/policy...Great that there are still active forums for both here at AVSIM!

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Pete,just tested it but unfortunately it doesn't have any effect on slipstream.Maybe it is just Jet engine wake turbulence-referred, which as a matter of fact is allways active in fu3.Thank you anyway!!!

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J.C.,Sorry, I was thinking of torque. There ARE prop-was effects modelled in FU3 however they are mostly set to low values. They are embedded inside the flight model of each aircraft and are easily edited. Wash effects are included for all lift surfaces.Now, here's what I'd like to do. I am not sure how much you know (or want to) about editing FU3 flight models but it's not hard (laborious, but not hard). What I'd like to do is edit the wash effects of the GeeBee to work as you explained. I can send to you all the files required, with instructions. What we learn from this can then be applied to all single-engined planes in FU3!I'm not saying that you would want to do all of them but I would certainly like to do some experiments with it and really don't have the time right now - I have a lot of FU3 projects happening. This would also be very useful for my T6 and F4U, which are currently on the drawing board ;)Please let me know if you would be interested. 'Good help is hard to find'. This is not a reflection of our developers - we're just all too busy and could do with some more helpers :-waveRegards,**************Jonathan Point**************"I'd rather be down here wishing I was up there than up there wishing I was down here"

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Although it's been a loooong time since I last used any fu3 editing tools I certainly wouldn't mind to try it again...Could you help me finding the links for those tools? Where can I download it from?The T-6 is particularly sensible to slipstream, so it should be great if you could model it that way.I also had the chance to talk to a real Spitfire pilot last here at a portuguese air show in Beja and he confirmed the need to be "gentle" with the throttle and use all your rudder trim + a lot of rudder input during takeoff to counteract the slipstream + p-factor effects.As a matter of fact he stated that when an engine failure occurs during initial takeoff run the less experienced pilot does not nill the rudder effects as fast as it would be required and the aircraft tends to "leave" the runway towards the side you were deflecting the rudder controls to (depends on CW or CCW engine being used...)I will send you a private message with my contact.Thx!!!

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Hi I'm new here but nobody mentioned the direction that the nose moves on tack off. FU 1 the direction the nose moved was left for a clockwise turning propeller (as seen from the cockpit) which is opposite from what you would expect on a real airplane. This was always curious to me.JakeInHartselSitting at 9,700 ft. msl

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I've mentioned this some time before -- it seems that FU and FS prop aircraft want to turn in opposite directions. I'm used to kicking right rudder to fly straight. However, the yaw tendency diminshes with speed, which is correct. To those of you flying real aircraft and to those of you "flying" various simulators, how do you find the torque effect? Regarding simulators, a prerequisite is to have coordinated rudder unchecked and to use pedals or a twist stick for realistic rudder control.best regards,Hans Petter

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Well Hans, it really isn't too different from flying a real plane, especially a taildragger. You just keep it straight with the rudder pedals. You do have the disadvantage of not being able to feel the plane as you would in a real plane, but most simulators are more forgiving than the real thing. To make it a little more complicated on most old tail draggers once you started your flare you no longer have a view of the runway over the nose of the plane and you have to look out the side of the plane and to judge how straight you are and adjust accordingly. It really is much easier than it sounds, and like everything a little practice and it becomes second nature.

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I understand, but it makes you feel good when you do a nice job of it! Even if its only virtual spectators there to see :-)But we all mess up at times, I have a broken prop in my garage from the time that I landed my Mooney Mite gear up. I believe that every pilot that I knew was at the airport that day.At least virtual spectators tell no tales once the computer is off:-)JakeInHartsel

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Gear up landings ? Ahh, yes. I remember making a lovely final approach to one of FU3's airports in my Beechjet a while ago. It really was a nice, centreline, touchdown zone beauty...right up to the point where the fuselage connected with the asphalt ! :-eekThat was a real shocker.Chris Low.

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Jake wrote: "You just keep it straight with the rudder pedals".Yes, I'm doing my best :-) However, I'm still a bit confused as to which direction a real propeller aircraft will tend to turn or yaw.We've got the rotation of the engine creating a force that will tend to rotate the aircraft in the opposite direction. Then there's the effect of the propeller blowing air backwards in a helical pattern. This stream of air will hit one side of the tail (horizontal as well as vertical) stronger than the opposite side.So, as you start rolling down the runway, will you kick right or left rudder? Then, will the turn tendency simply diminish as you pick up speed or will it change to an opposite turn at some point / under some circumstances? Hans Petter

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