+TexMurphy 0 Posted January 24, 2007 Hey Charles, Sorry for posting this in public as I dont know your email addy and dont know your exact forum name I thought Id just post my question. I was thinking that I might model the N28´s wing rip by removing all lift above a certian speed but Im quite lost on the mach tables. Is there a table for variable CLa and or CL0 based on air speed??? Thanks in advance Tex Share this post Link to post Share on other sites
Guest capun Posted January 24, 2007 Charles is having fun tackling Great Whites Down Under, don't expect a reply until next week Share this post Link to post Share on other sites
+Tailspin 3 Posted January 24, 2007 Charles is having fun tackling Great Whites Down Under, don't expect a reply until next week I hope he gets time to do some fishing too. Share this post Link to post Share on other sites
+Tailspin 3 Posted January 24, 2007 Tex, this may be worth a read. The N.28 had several service problems. Most remembered among them was the failure of the upper wing in a dive, the leading edge seperated from the aircraft pulling the fabric off the wing. This failure occurred at least six times (Meissner twice, and once each to Hall, Rickenbacker, Heinrichs and Casgrain.) In each case the failure occurred during a pull up from a power on dive. It was not the dive, but the pull out that wrecked the wing. There are several accounts of vertical dives, for instance Hartney states 'I was soon showing the squadron how this ship could dive vertically at the ground' (2); from this it can be infered that it was possible to safely dive this airplane as long as care was taken with the pull out. Despite the grotesque appearance of the failed upper wings in most cases control of the aircraft was maintained and the machines were safely landed. Had the ailerons been on the top wing like in pervious models this failure would have been much worse. The failure seems to have been limited to the ships of the 94th and 95th. It is quite possible that either the design had been improved by the time aircraft were delivered to the 27th/147th or as Hartney suggests these squadrons pilots were better prepared to cope with their machine's flaw. Hartney proudly noted 'no Nieuport of ours ever stripped it's wings'(3). The Nieuport Page Share this post Link to post Share on other sites
Gr.Viper 131 Posted January 24, 2007 Huh... Oh, I was also wondering if it's possible to increase drag when some part falls off or gets damaged. Say, you place fabric on some place as a separate object and then this cover gets destroyed - would it be possible to imitate the effect of such stuff happening? Share this post Link to post Share on other sites
+EmlD 3 Posted January 26, 2007 Huh... Oh, I was also wondering if it's possible to increase drag when some part falls off or gets damaged. Say, you place fabric on some place as a separate object and then this cover gets destroyed - would it be possible to imitate the effect of such stuff happening? The damage fabric placement on top wings is possible, but i have no idea how to connect this damage with the game.... we have: 1.Damage from coallision 2.Damage from bullets in this case we need damage from too hight speed....while diving, and it should influe only top wings...the part where the fabric damage node is placed... Any other ideas? EmlD Share this post Link to post Share on other sites
+Tailspin 3 Posted January 26, 2007 IMHO you shouldn't get too carried away with implementing this effect. As the article above relates the flaw was not so much speed related as it was pulling out of the dive too abruptly. In other words you could dive at high speeds, you just couldn't yank the stick back without care when climbing out. Big difference. Share this post Link to post Share on other sites
+peter01 2 Posted January 30, 2007 Hmmm, this is from the Society of WWI Sim Artisans (SWWIA website), who do extensive mods for RB3D: " Nieuport 28. Loosing the competition with the SPADs, the 28 was used as a stopgap aircraft by American pursuit squadrons when they first arrived in France. Fast and manueverable, it was also fragile, with a tendency to shed fabric from the top wing in a dive. It saw limited action and was soon replaced by SPAD XIIIs. " This is how its modelled in RB3D and in OFF (for N17, similar maybe?). Who knows really I guess, but any plane that lost a wing pulling up from a dive could probably lose it in a dive as well. Maybe both are right. Share this post Link to post Share on other sites
Guest Charles Posted January 30, 2007 (edited) Tex: Sorry for the slow response (beach weather here, you know how it is...) Reducing the lift to zero at any given speed is easy. For each lift surface, such as the wingtip, you will see (or can insert) tables to make the lift coefficients vary with speed, like in the following example: CL0MachTableNumData=3 CL0MachTableDeltaX=0.10 CL0MachTableStartX=0.00 CL0MachTableData=0.996,1.000,1.013 CLaMachTableNumData=3 CLaMachTableDeltaX=0.10 CLaMachTableStartX=0.00 CLaMachTableData=0.996,1.000,1.013 The above means that, say for CL0, the "base" factor is multiplied by 0.996 at speeds between 0 and 0.10 Mach (64.4 knots), then by 1.000 at speeds to 0.20 knots (128.8 knots), etc. Work out the speed at which you want your "simulated shredded wingtip with no lift" effect to kick in, and then just work backwards to construct your table with a factor of 0.00 cutting in at that speed. Edited January 30, 2007 by Charles Share this post Link to post Share on other sites
Gr.Viper 131 Posted January 30, 2007 Won't have the shredded part regenerate then at lower speed? I think the best way would be asking TK to add some kind of structure limits - +-G, airspeed etc. Share this post Link to post Share on other sites
Guest Charles Posted January 30, 2007 That's right (assuming that, without the lift, you can actually pull up and reach a lower speed, rather than just hurtling into the ground). What is needed for for this effect to really work is a variable like DetachSpeed=, to achieve a permanant separation. Share this post Link to post Share on other sites
+peter01 2 Posted January 31, 2007 Simulating some probs at excessive speed sounds great :yes: until changes such as DetachSpeed etc are added. I guess hard at first, but once done ...........????? I was also wondering if another way to go is using the stall features to simulate probs at high speeds? That is if kicking in at low speed, maybe it can kick in at high speeds? Recoverable, but limits aircraft performance. Share this post Link to post Share on other sites
+TexMurphy 0 Posted January 31, 2007 Thanks for your response Charles, Ive managed to figure out the mach tables and hence managed to remove the annoying auto level ability of the N28 which was inherited from the "default" file we started with. I did obandon the simulation of the breakin wings, loss of lift was one idea that got thrown out, compression was another. Compression would have been the best way to simulate it imho as compression prevents you to pull up above ceration speeds. Though I didnt like the "freeze" function that had to be used as the. Still maybe this could be done better by having a mach table for the pitch momentum property. Though I really feel we should wait and see if TK ever adds it. Tex Share this post Link to post Share on other sites
+TexMurphy 0 Posted February 2, 2007 Charles Ive got one more question. How do the stall values work? Tex Share this post Link to post Share on other sites
Guest Charles Posted February 2, 2007 The stall parameters for the lift surfaces are as follows: CLMax is the maximum Lift Factor Alpha is the Angle of Attack AlphaStall is the angle (in degrees) at which the aircraft stalls AlphaMax is the maximum angle of attack (in degrees) the aircraft becomes uncontrollable or enters a spin AlphaDepart is the maximum angle of attack (in degrees) before the aircraft will definitely spin All of these Alpha terms are in degrees from horizontal The lift "curve" is modeled as 4 connected straight line segments - first part with slope of CLa to AlphaStall, then at reduced slope to AlphaMax, then flat top segment to AlphaDepart, and it drops off from there. Also, past AlphaStall, there is some randomness subtracted, so none of the wing panels have exactly the same amount of lift. (this randomness increases in magnitude as Alpha increase). StallMoment is the additional pitching moment you get when the wing section starts to stall. positive pitch (+) makes it so it pitches up as you stall (making it more unstable), negative pitch (-) makes it so it pitches down when you stall (making it more stable). The default value, if you don't specify a value, I think, is -0.02, which I think would make for gentle mushing forward type stall I was looking for... StallDrag is the additional drag caused by the stall. There are also a couple of other stall/depart variables which SF has which work for prop planes, although I am not sure if they are all implemented in FE. They should have default values so that if you don't specify them, you just get the default behaviour. PostStallCma= determinesthe Cma (pitching moment due to Angle-of-Attack (Alpha)) past stall. Pre-stall, the engine uses lift value and xac value to calculate the pitching moment. Once the wing stalls and departs, additional pitching moment of StallMoment + the PostStallCma * (AoA - AlphaDepart) is added. I think this defaults to -0.2 or something. StallHysteresis= (should be from 0.0 to 1.0) determines how far the AoA has to be reduced in order for the airflow to reattach itself. I think 0.0 means the wing section will be unstalled as soon as AoA goes back under the stall angle, 1.0 means wing will unstall only when AoA goes back to 0 deg. I think the default is 0.4 or something. PostStallZeroLiftAlpha = this is the angle at which the lift goes down to zero. Post AlphaDepart, the lift is linearly reduced down to zero at this angle. I think this defaults to 90-deg... And also, for control surfaces like flaps and slats (not really relevant for WWI aircraft), you also have DeltaStallAlpha, which is the change in maximum alpha before stall due to control surface deployment. Share this post Link to post Share on other sites
Old Guy 0 Posted February 2, 2007 Charles, Your mention of slats and flaps triggered a thought. Yeah, yeah, I know. It IS an odd phenomenon. WW1 aircraft didn't have flaps, but they did have one huge drag-inducing part -- the propellor. A broadbladed, fixed pitch prop should produce a lot of drag when the engine speed is reduced, such when descending to land. I've had a lot of trouble slowing any FE aircraft to a reasonable landing speed. Is this type of prop drag modeled in FE? Jim Share this post Link to post Share on other sites
+TexMurphy 0 Posted February 2, 2007 Thanks Charles Alot to digest and alot to work with but very good stuff!! Tex Share this post Link to post Share on other sites
Guest Charles Posted February 3, 2007 Old Guy: I don't think prop drag is modelled, but it is a good thought. I will put my thinking cap on.... Share this post Link to post Share on other sites
+TexMurphy 0 Posted February 7, 2007 Sorry to bug you again Charles... The Alpha tables what is the scale in and what does it measure??? Tex Share this post Link to post Share on other sites
Guest Charles Posted February 8, 2007 Alpha is the angle of attack (the angle betwen the mean chord of the lift surface e.g.wing and the relative airflow). It is measured in degrees. Share this post Link to post Share on other sites
+kreelin 2 Posted February 10, 2007 (edited) ...WW1 aircraft didn't have flaps, but they did have one huge drag-inducing part -- the propellor. A broadbladed, fixed pitch prop should produce a lot of drag when the engine speed is reduced, such when descending to land. I've had a lot of trouble slowing any FE aircraft to a reasonable landing speed. Is this type of prop drag modeled in FE? Unfortunately not... This is something missing in TK's series. Specially with WWI planes that don't have airbrake ;). I've already tried to model this in Jet Flightmodel long times ago but never find a way to do it... I hope TK will do something about it one day ;) Edited February 10, 2007 by kreelin Share this post Link to post Share on other sites
+Tailspin 3 Posted February 10, 2007 You gotta slow down the old fashioned way...a couple of quick s-turns to scrub off my initial approach speed works for me. Share this post Link to post Share on other sites
