----------------------------------------------------------------- There were several models of the DC-9 with different length. The DC-9-20 is the short model with high-lift devices and powerful engines. It's said to be called "DC-9 sports" or "DC-9 hot rod". The DC-9-30 is the most widespread model with a stretched fuselage. The DC-9-40 has an again stretched fuselage and even more powerful engines. .mod files: My 3D models are work-in-progress for some time now, but I simply have no time to make them in RMK. The parameters work fine, though, with the DC-9 by 'dl3fy' (Jürgen Dreyer). The landing gear isn't quite correct and flaps and ailerons are completely wrong. But that doesn't influence the flight behaviour, and there are even two "propellers" so that asymmetric thrust may be simulated. The model seems to be a -30 but I'm not sure. .par files: The parameter files 'DC-9-xx JP.par' each render the flight behaviour of a 1:10 scaled model powered by two turbines, e.g. JetCat P60 with a thrust of 62 N each. The parameters were derived from the few information given at http://www.thilokyritz.de/ by Thilo Kyritz for his DC-9. His model seems to be not completely true to scale, but here a true model of the real airplane is assumed. The 2.845 m / 112 in wing span, 93.5 dm² / 1450 in² wing area and 19.5 kg / 43 lb weight give a 210 g/dm² / 65 oz/ft² wing loading for the DC-9-40. This is very high but causes no problems at the given model size. Engine thrust was set to only part of the thrust of the JetCats, though, still giving a 0.47 thrust/weight ratio. That's sufficient even for grass runways and considerably more than the 0.272 value of the real aircraft. This value is set in the parameter file 'DC-9-40 JP scale.par' for comparison, but you'll need a tarmac runway like that of the Arizona Model Aviators to try it out. The -20 and -30 models each have a slightly lower weight / wing loading and higher thrust/weight ratio. By the way, jet engines with only 26 N thrust would suffice. The parameter files 'DC-9-xx EP.par' each render the flight behaviour of a 1:16 scaled model powered by two electric ducted fans (EDF). Assumed are DS-30-DIA (3-ph) fan units by Daniel Schübeler, e.g. with Lehner 1520-14 motors. At the website http://www.schuebeler-jets.de/ Daniel states exactly the needed 9 N / 2 lbf static thrust at 0.4 kW electric input power (e.g. with 32 A current draw from 12 cells NiCd or NiMH) and 60% efficiency for this drive. Wing span is 1.778 m / 70 in and weight was limited to 4.9 kg / 10.8 lb. Now the 36.5 dm² / 566 in² wing area gives a fairly high 134 g/dm² / 44 oz/ft² wing loading which should not be exceeded for good controllability of the model. However, Norbert Rauch states 6 kg weight for his -20 and 6.5 kg for the -30 and -40 at his http://www.rauch-airliner.com/DC9E.htm web page. Using the parameter file 'DC-9-30 EP heavy.par' you may test what would be the flight behaviour. The 178 g/dm² / 58 oz/ft² wing loading makes for a just controllable model in the simulator, anyway, at least on a spacious airfield with tarmac runway. .wav files: The files JetCat.wav and JetCat_.wav are not recorded but only processed by me. I only cut out short pieces where loudness is fluctuating not too much. Years ago, they were published with jet models on http://www.rc-sim.de - creator unknown. They should fit better than other jet sounds recorded from real planes. The files edf.wav and edf_.wav were simple copies of the REFLEX AXI sound files. They were renamed to allow easier replacement by the real sound of an electric ducted fan (EDF) if I ever record it for REFLEX. If you have an EDF drive on whatever model, please help with recordings (send an e-mail). Meanwhile the edf.wav file is a processed version of an EDF (German: impeller) sound file published by flyingbaer (http://www.flyingbaer.de/). For both variants of the model (jet and EDF) the thrust/weight ratio 0.47 or 0.37, respectively, is by far sufficient. Even despite the high wing loading and small size of the model it is well controllable. However, effective wing flaps including leading edge slats (which are not renderable in REFLEX) are assumed. Even with the low true-to-scale thrust/weight ratios the model is still controllable, assumed you know how to fly such a thing. The model is quite fast but obviously well behaved. The model is trimmed to take-off by itself or with a bit help and climb steadily at 1/3 flaps (15°) and full power. Level flight is then stable at a power setting of 40 to 50% and maybe a bit down elevator. In clean configuration (flaps and landing gear retracted), it will glide steadily as well as stay level in powered flight. On final approach, set full flaps (50°) and much power to adjust a shallow glide slope. It's nicely simulated that there's not much trouble if one engine fails. Set up to 5% 'Probability of engine failure' in the simu- lation parameters (F6). More REFLEX models and the latest versions are on my page http://time.fh-augsburg.de/~erd/Modellflug/textDownloads.shtml Enjoy! Burkhard Erdlenbruch mailto:Burkhard@Erdlenbruch.de http://time.fh-augsburg.de/~erd/Modellflug/textReflex.html -----------------------------------------------------------------