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Hello fellow FE/FE2 flyers, As a continuation of my experiment to include over-compression tendencies in the 200hp Daimler engine for Geezer's Junkers J.1 model, I did some (successful) tweaking of the previously tweaked data inis for the the BMW-powered Fokk. D.7 and late, 200hp Alb. D.5a. Tinkering with the following values in the data inis is required to get things working well, under the Engine section: AltitudeTableNumData AltitudeTableDeltaX AltitudeTableData The NumData should reflect how many values are present under the AltitudeTableData section. The DeltaX number is finicky, the general rule being that a higher number gives more powerful engine results across wider alt. bands but is perhaps less historically realistic, while in some cases a lower number is required, for example to "unglue" the AI from the ground in case the AI has trouble handling a particular plane, and also to create more subtle and gradual performance drops across smaller/thinner alt. bands. [Edited this section to include more accurate info.] TheAltitudeTableData entry begins with a value of 1.000 - ground level number, and then gradually falls off to 0.000. Correct over-compression of an engine requires that a number higher than 1.0, usually a few entries that are higher than 1.0, are included at the start of the AltitudeTableData entry - to generate the correct effect if an over-compressed engine is at full throttle near sea level. Values under the FlightControl section, particularly top speed values, then become a reflection of top speed at altitudes between about 1000 and 1500m - typical heights at which Idflieg would have over-compressed engines tested. (This also depends on the DeltaX number and where the AltitudeTableData value of 1.000 begins: for example, values of 1.200, 1.050, 1.000, etc., with a DeltaX no. of 500, would mean that 100% performance is at 1000 m alt.) It's no wonder that there is some confusion therefore regarding top speeds of the BMW-powered Fokk. D.7, and if its numbers are reflections of what happens near sea level or at 1 km alt. approximately. [Added important info. here too.] Here is a snippet from TheAerodrome.com for the 180hp Mercedes (au) installed in many Fokk. D.7s: "Climb rate is 5 m/s at sea level, falling linearly to 0 m/s at 6 km, marked as the "theoretical ceiling". Climb rpm begins at 1400 rpm at sea level, falling to 1310 rpm at 5600m." "Level speed: 0 km: 190 km/h @ 1570 rpm 1 km: 188 km/h @ 1580 rpm 2 km: 182 km/h @ 1530 rpm 3 km: 177 km/h @ 1490 rpm 4 km: 167 km/h @ 1430 rpm 5 km: 152 km/h @ 1360 rpm 6 km: 124 km/h @ 1280 rpm" Here are the results for the newly tweaked BMW-powered Fokk. D.7: near sea level: 210-211 kph @ 100% throttle near sea level: 176-177 kph @ 70% throttle (cruise, not using high alt. throttle) 1000 m: 201 kph @ 100% throttle (this is the top speed usually cited for the BMW-powered D.7, but probably refers to at alt., not at sea level) 1500 m: 198 kph @ 100% throttle 3000 m: 187 kph @ 100% throttle 4000 m: 176 kph @ 100% throttle climb rate to about 1000 m, at 70% throttle, is around 3.5 m/s; climb rate remains fairly consistent beyond 1000 m, at 100% throttle, if speeds in 120s and 130s kph are maintained Results are a noticeable improvement over the Mercedes-powered D.7 (no wonder pilots wanted this type). Here are results for the newly tweaked 200hp Mercedes-powered Alb. D.5a: near sea level: 206 kph @ 100% throttle near sea level: 183 kph @ 70% throttle (cruise, not using high alt. throttle) 1000 m: 202-203 kph @ 100% throttle (Goering supposedly reported maintaining over 200 kph in level flight in an Alb. D.5a...perhaps the 200hp variant?) 1500 m: 198-199 kph @ 100% throttle (this is the top speed sometimes cited for the late variant Alb. D.5a, again perhaps referring to at alt. and not sea level) 3000 m: 187-188 kph @ 100% throttle 4000 m: 177 kph @ 100% throttle 5000 m: 165 kph @ 100% throttle 6000 m: 110-112 kph @ 100% throttle (noticeable drop, since exceeding its ceiling here of about 5900 meters) 6025 m: 90-95 kph @ 100% throttle (begins to shudder and stall) climb rate to about 1000 m, at 70% throttle, is around 4 m/s; climb rate is around 3 m/s at 100% throttle beyond 1000 m, in 120s and 130s kph (slamming the throttle to 100% below 1000 m would not have been recommended historically, but gives a climb rate of about 5-6 m/s, similar for the Fokk. D.7...probably used in emergency scenarios) Results for the late Alby. are a noticeable improvement over the 180 hp Mercedes (au) Albies, and similar to results for the Fokk. D.7 - watch the wings though in dives on the Alb., especially with the now excess power. Also interesting is the historical realism of how the speed advantage at alt. for the high-compression engines remains fairly consistent across the altitudes (dropping off in small steps of about 5-10 kph per 1000 m), and then severely drops off close to the ceiling for the type. A gradual, more "curved" drop of speed for high-alt. engines should be seen for WW2 types - but is usually, mistakenly assumed of WW1, over-compressed types too, which would remain fairly consistent in power until close to their ceiling (see relevant discussions on TheAerodrome.com for more info.). Attached are the two tweaked data inis (will roll this eventually into a ver. 9.0 of the FM update pack). I'm still debating if I will tinker with the 180hp (au) Mercedes-powered types...the benefit of over-compression on those types would be small, probably too small to make any noticeable difference in FE/FE2. Happy flying, Von S [Files included in ver. 9.0 and later of my FM updates pack.]