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jcomm
October 28th, 2008, 03:10
Hi!

It's been a long time since my last post...

I've been flying for real :-) but recently I reinstalled fsx+sp1+sp2. I lost Airwrench :-(

One question: Is there a way to design a prop (single, nose mounted) prop aircraft fro MSFS that properly simulates the effects of power up on yaw.

Say you're on short final and decide to go around. In real life pushing your throttle to the stop will require rudder to counter slipstream effects, but ONLY rudder!!! The airplanes yaw a lot sometimes, but there is no noticeable bank (due to yaw?). You use rudder mostly. In all MSFS aircraft youa also have a LOT of bank, allways!!!!

This problem also affects flight performance on twins and multi-engine aircraft in general when one of the engines fails and assymetric thrust exists. Most of the time there is a LOT of induced bank, when there should primarily be yaw towards the dead engine side.

Finally, is there already a nice, trustworthy implementation of the turn coordinator in MSFS. There are commercial versions of some instruments that you can easily add to your instrument panels but as far as I know no one has ever came up with a proper turn & slip instrument...

fliger747
October 28th, 2008, 10:08
JC!

Low powered propeller aircraft will mostly have a yaw effect from the P-factor in which the swirl of the propeller contributes a side load on the verticle stabilizer. The aerodynamic dampening of the proportional large size of the wings results in a very small "torque" effect. In a high power loaded aircraft the wing area may be similar, but the power loading might be 15-20 times as much! So a torque roll, exceeding the aileron capacity to counteract at low speed may be quite possible. Re-download Airwrench, Jerry won't charge you to re-activate. There are a whole bunch of modifications available there!

It is possible to more or less replicate such charcteristics as far as they are accuratly known. I have flown a lot of the multi's with an engine (or two) out, a lot in FS and believe that fair replication of such flight charcteristics is possible. Milton Shoup's Beech 18 is a good one as is the Outhouse A-26. Implicet in much of this is the effect of adverse yaw. In a twin, up to 5 deg of bank is normal technique, to help compensate for the effects of the dead engine. In a twin some aysemetric lift will exist as the airflow over the wing of the good engine will be enhanced.

You are flying in FSX or FS9? My biggest beef with FS is the lack of an ability to easily lift the tail of taildraggers realistically, even at rest, as can often be done IRL.

What planes have you been flying? I know I have seen some good turn coordinators, easy enough to steal one and substitute it in your panel cfg file.

jcomm
October 29th, 2008, 01:50
JC!

Low powered propeller aircraft will mostly have a yaw effect from the P-factor in which the swirl of the propeller contributes a side load on the verticle stabilizer. The aerodynamic dampening of the proportional large size of the wings results in a very small "torque" effect. In a high power loaded aircraft the wing area may be similar, but the power loading might be 15-20 times as much! So a torque roll, exceeding the aileron capacity to counteract at low speed may be quite possible. Re-download Airwrench, Jerry won't charge you to re-activate. There are a whole bunch of modifications available there!


Good idea! But that will place me for hours in front of the PC again, just like in good-old-days, before offering all of my MSFS add-ons, ELITE, etc... and also all of my hardware 8-)

I re-installed fsx, then applied both service packs and recovered a few airplanes I had bought - LevelD 767, Pilatus PC-12 and Aerosoft Twin Otter.

The power-induced bank in msfs appears to be directly related to how internaly the sim "connects" power to torque effects. There are a few parameters one can tweak both in the ".CFG" and ".AIR" files (torque_on_roll, for instance) but I never figured out how to properly set it... If you try to model a realistic prop engine for, say, a C152, the yaw due to slipsream will be almost unnoticeable. If you increase prop effects than you'll have too much torque :-( I never played with the default prop tables in MSFS. Although Jerry has a very nice explanation of how it works, I do not have real data to base my tweaking...



You are flying in FSX or FS9? My biggest beef with FS is the lack of an ability to easily lift the tail of taildraggers realistically, even at rest, as can often be done IRL.

What planes have you been flying? I know I have seen some good turn coordinators, easy enough to steal one and substitute it in your panel cfg file.

I am using fsx only. I no longer have fs9. Taildragers propwash effects were much more realistic in fs2002, if I can recall... Something happened in between - probably one of thiose cuts in the AIR file parameters MS loves to do...