Zur's FM / OPS "tips'n tricks"

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Author	Topic: Zur's FM / OPS "tips'n tricks"
Zurawski Pilot	posted 04-21- 09:44 AM OK ... Call it "one-up-man-ship" or what have you ... Tails fine tutorial and SV's leap to cunstruct a FM document has ...well ... made me feel like lazy twit! That said ... Maybe I can contribute to the learning process with my "tips'n tricks" 1.) I use OPS1.2.1 for "all" FM tweakage. (now that Bryan kinda fixed the canopy and obprob quirks). There is "nothing" pertaining to a FM that can't be done in OPS. The fact that you can "see" your FM makes a world of difference! 2.) "Baby steps". Don't try to do everything at once and save often. Note" - It's almost imperative that you take notes regarding what's been changed. There quite franky is nothing more fustrating than to make a change and find it's "no good" and not remember what the original settings were. 3.) Build/add/adjust your inertia boxes to both represent the mass of the aircraft "AND" also reflect the parts they represent. 4.) Get the basics first. It's an act of futility to try and model a detailed FM from scratch. Get the known basic performance numbers in the ballpark before fine-tuning or attempting to add neuances. "Every" change you make to a FM will affect another part of it. my pet-peeve* ... GET THE PLANE TO FLY TO KNOWN SPECS FIRST AND FORMOST. 5.)To adjust the Center of Gravity more accurately, it's better to reduce inertia box "density" in the nose, rather than add "density" to the tail. Reason being, if you add to much to the tail, you will notice greater inertia "YAW" from the rudder than what is realistic or prudent. OK ... That's a start. I'll add more as I remember them! [This message has been edited by Zurawski (edited 04-21-2000).] IP: Logged
Sv Pilot	posted 04-21- 10:27 AM This is awesome Zur, keep it up! These are the kinda tidbits that most of us need... otherwise we learn the hard way, re-inventing the wheel over and over again with the wrong inertia volumes on the spokes ------------------ -Sv =FC= WWI in SDOE! IP: Logged
Zurawski Pilot	posted 04-21- 11:12 AM More tips ... Changing roll performance: You can alter roll performance several ways. One is you can either increase or decrease the degree of travel in the ailerons. (This is assuming you don't HAVE historical data) -OR- If you have historical data for the DOT (like I did for the P47D and the 109s. You WANT/SHOULD use as much historical data you can before fudging anything)... You can use the wings inertia densities to assist you in this ... If you've ever sat in a swivel-chair (or are a avid ice-skater).. and spun youself. If you stick your arms or legs out you'll notice you will spin slower ... If you draw them in you will spin faster. You can apply the same principal to the roll-rate on flight-model! By increasing the object volume "density" ... in the wing roots ... and decreasing the density in the wing tips. You can manipulate the roll-inertia to either speedup or slow-down roll speed! (This principal is also why you don't want to have too much wieght in the tail section of an aircraft. Too much produces the adverse "YAW or swinging in the planar axis of the aircraft.) [This message has been edited by Zurawski (edited 04-21-2000).] IP: Logged
Zurawski Pilot	posted 04-21- 11:24 AM Another tip (I'm on a roll) To change an aircrafts turn-speed: You can increase the degree of travel in the elevators. Again like the roll-speed, Use historical data is you have it. -AND OR- Manipulate the inertia volumes in the nose an tailsections to adjust the Center of Gravity fore and aft. The Center of Gravity or "CofG" immediatly and directly affects both the turn speed and the "how easily an aircraft spins/departs" ... Bare in mind the closer to the center of the aircraft you make your changes, the less drastic your changes will be ... If you add too much density to the very end of of a aircraft, you will notice higher degrees of "inertia YAW" or pedullum in the tail than if you added the density closer to the midline or reduced it from the nose section. [This message has been edited by Zurawski (edited 04-21-2000).] IP: Logged
Ronin Pilot	posted 04-21- 11:24 AM Zur: Great tips! Thanks... That no. 5 is going to help me right now... "5.)To adjust the Center of Gravity more precicly, it's better to reduce inertia box "density" in the nose, rather than add "density" to the tail. Reason being, if you add to much to the tail, your notice more inertia "YAW" from the rudder than what is realistic." Thank you, thank you, thank you.... Ronin IP: Logged
Zurawski Pilot	posted 04-21- 11:55 AM Yet another tip ... Keeping a "tippy" planes wheels on the ground. Add physical weight to your wheels and wheel assemblies. (of cource historical data is best if you can get it) This helps move the CofG "down" so tippy planes are more controlable. Bare in mind once the wheels retract the weight is simply obsorbed into the total weight of the aircraft! IP: Logged
Laika 801 Pilot	posted 04-21- 01:08 PM Great stuff ! Can you put this in a doc file that I can download somewhere. So I can read and think about it like in a book IP: Logged
Zurawski Pilot	posted 04-21- 01:33 PM ... Laika, I'm hoping SV uses this stuff in addition to Tailslides tutorial and makes a "definative source" document on FM'ing (SV ... I "hope" you correct my "two-finger speed typing" errors) IP: Logged
Zurawski Pilot	posted 04-22- 12:01 AM more ... At this point and time FS doesn't model either WEP or turbo ... Because of this is one were to use "historical" engine HP and RPM values for engine that were equipped with these ... It would would be near impossible to model top-speeds and or high-alt performance. What I've done for all the aircraft that use either of these ... I've over modeled them to reflect it. For instance ... The P47Ds engine is rated at 2300 HP @ 2700 RPMs. In order to get 428mph @ 32000ft ... I had to boost the settings to 2800 HP @ 3000 RPMs ... Which closely models this engine using constant turbo. NOW ... I don't advocate "fudging" ... BUT IMHO this is an exception. I justify this "fudge" by having many sources state that many pilots had their turbos wire open in the field to get as much "UMPH" from the engines they could ... [This message has been edited by Zurawski (edited 04-22-2000).] IP: Logged
Sv Pilot	posted 04-22- 07:18 AM Have you seen my site Zur? I don't think I ever spelled "the" correctly once! teh th te het -Sv IP: Logged
Zurawski Pilot	posted 04-24- 10:17 AM Airfoils .. OK... Obviously there are only a finite number of airfoils that "came" with the game. And airfoils "DO" have alot to do with flight-modeling ... FS uses airfoils derived from NACA airfoil profiles. While not all airfoils are listed or available. Efforts should be made to find one for the aircraft your modeling ... if not on that is at least "close". What to do with'm once you have one? If you open one of FS default airfoils with say wordpad or MS Word ... You'll see its basicly a binary record of the airfoil. Note that it's broken into three regines ... XXXairfoil ... XXXairfoilup ... XXXairfoilDn. If you open a NACA airfoil record ... you'll see a simular broken outline. What you do is cut/copy and past the NACA data-block into/replace the existing ones in the default .sm file ... NOW ... You "HAVE" to keep the naming conssesions the same ... I.E ... if the .sm is called spitfoil which is eight (8) letters ... your new .sm HAS to also be eight letters. Do this thoughout the doument (ie ... where it says XXXairfoiup, XXXairfoildn ..) THEN ... "Save as" and make sure to use the same caming consession as you used inside the document. Note that you will have to add this new airfoil to the startup.ppf (depending on the airfoil, sometimes you have to list is both as a .ppf AND a.sm ... don't ask me why) ... An VIOLA .. new airfoil! IP: Logged
Tailslide Pilot	posted 04-24- 10:26 AM Zur and I have a philosophical difference here.. I leave RPM and HP at the historic values and fiddle with the propeller shape to get the performance to match. Either way is good though. TS IP: Logged
Zurawski Pilot	posted 04-24- 10:37 AM "philosophical differences?" Bah! ... I'm just right that's all. j/k Actually ... I "do" agree with Tail to a degree ... I guess I shopuld have qualified my original post by saying ... "try every other option firsy before doing this) I personally have found that playing with the prop-data only can take you so far ... In the case of the P47D ... the default (non-turbo).. engine variable just could not muster the top-end-speed at alt, despite WHAT I did to the prop data. There-in lies the reason for the boost in HP and RPM (And I already justified my logic) IP: Logged
Tailslide Pilot	posted 04-24- 10:43 AM Ok.. yes I set mine at 'constant WEP' horsepower too. I figure if/when engine wear and overheating gets added to the sim we won't have to change anything. TS IP: Logged
jedi Pilot	posted 04-24- 11:44 AM Three's in! Constant WEP HP is what I used as well. Actually, it should be possible to use an obExec to simulate WEP horsepower on the engine, and higher fuel consumption as well. The only thing missing is the increased wear on the engine (not much reliable data on that I fear) and a way to make the WEP "run out" after a few minutes. Is there a way to attach a "timer" to an obExec function? ------------------ --jedi-- IP: Logged
bjorn Pilot	posted 04-24- 11:54 AM A way to fake it may be to use an alternative small "WEP tank" When it's empty the engine is dead. The problem, though... how do you manually trigger the WEPon and WEPoff functions? _ /Bjorn. IP: Logged
Tailslide Pilot	posted 04-24- 11:56 AM WEP doesn't run out like nitrous, you can overstress your engine until it quits. There's pretty interesting description of its use in here: http://www.zone.com/fighterace/news/tbltnewsbobgoebel.asp TS IP: Logged
jedi Pilot	posted 04-24- 01:51 PM I suspect that any of the systems, either water injection, nitrous injection, or manifold pressure overboost, could probably be used until the system ran dry or until out of danger occasionally without any significant damage to the engine. But running the plane routinely at those settings would probably wear out the engine a lot faster, and of course increase the chance that it would fail inflight. As for a "trigger," the only thing in the sim I can think of where the pilot can trigger an obExec is the bailout function, where the "Flyboy" obFunc is triggered. I guess I'd be willing to trade the ability to bail out for the ability to model WEP But maybe that also means that you can "call" an obExec somehow with the commands in the sim. That way any unused command (bomb doors in a fighter, for ex) could perhaps be "re-wired" to the WEP function. ------------------ --jedi-- IP: Logged
Laika 801 Pilot	posted 04-24- 04:31 PM Laika 801 did not underatnd you any longer. As you can see I cant even write right. What is a WEP ? Is this the same as the so called "takeoff-power" ? I used the full takeoff power on the I16 - of course you dont know if you got the full power or not because of the obProb I added to the engine. As I know the soviets flew all the time with full power - a bit rough those guys, but I like this way of flying - "dont mind if your engine explodes as long as you can get faster...". LK IP: Logged
jedi Pilot	posted 04-24- 06:32 PM WEP = War Emergency Power. A setting where you run the engine ABOVE it's normal maximum takeoff power. Only possible on some aircraft. P-51 could choose to exceed the maximum allowable manifold pressure by pushing the throttle though a wire gate or detent. "The book" said he could do this for 5 minutes, but you could do it until the engine failed if you had to... Most of the German fighters had a Nitrous Oxide injection system that boosted power (usually at higher altitude) but the boost only lasted as long as the nitro. The Navy fighters and the Jug had water injection, which did the same thing (but worked better at low altitude than the nitrous system) and again, the extra power ran out with the water. As Laika's and Team Jug's engine setups show, you CAN vary the engine output in SDOE. The problem is doing it ON COMMAND rather than as the result of damage or by defining an initial random power output. I still can't believe the original coding didn't include WEP. You wouldn't build a jet sim without afterburners... ------------------ --jedi-- IP: Logged

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