First of all thanks Yo-Yo for your explanations about the trim, stick forces, etc. The flight modeling of old warbirds when there is not much information about must be a considerable effort and any access to data is a treasure. I bought the module a year ago but I didn't started with the Bf 109 in DCS until a few weeks ago, when I also bought the Normandy 1944 Map + WWII Assets Pack.
Every time you add or take down power, different airspeeds, altitudes, center of gravity change, etc, the flight dynamics change and you need to change the trim to get level flight. Each aircraft is different, some require a lot of trimming, some very little. Usually it depends on the horsepower and design of the bird, based on what it is made for. The horizontal stabilizer prevents up-and-down, or pitching motion of the aircraft nose to get more stable flight.
What I cannot understand, it even shocks me, is why an aircraft design with a variable incidence tailplane (horizontal stabilizer) is limited to use only a small portion of it's trim travel band. Mostly any other setting than +1.5= "FULL AIRCRAFT NOSE DOWN" in the trim scale causes a high nose up condition at all speeds. Even at 200 Km/h, the 0 trim setting it's a very high nose up trim input. Thus most of the tailplane trim settings, from 0.5 to -6, are simply not usuable to get a stable flight at any range of speeds, power setting, etc. That's roughly the 80 percent of the variable incidence tailplane trim travel band not usuable to achieve a stable flight. This is how the Bf109-K4 behaves in DCS.
When you spawn in the air the trim scale setting is 0 and the IAS 500Km/h, 1.4 ATA. 100Km/h are lost in just a few seconds if you don't correct inmediatly the trim to 1.5 "full aircraft nose down", that's extremely tail heavy. I really don't like that loss of speed when I launch a dogfight against Spits or P51s. Even for take off I set the tailplane trim to 1.5 full nose down to avoid stall conditions just after lift off.
Even more, according the graphs, "how in the hell to gain a sustained climb at Stab incidence=0 (0 setting in tailplane trim band), even at a relative low speed 200 Km/h and 2600 rpm-1.3 ATA, you have to push on the stick!".
May be it's exactly the opposite and your red caption statement on the graph "At the whole range of IAS, for stab angle 0...+1.5 the stick must be PULLED more or less" it's really the correct one?. Yes, PULL to obtain a sustained climb at a certain angle with increasing forces as the IAS increases with stab trim settings from 0 to +1.5 aircraft nose down, that's the logical answer. Could it be an error in the graph or missinterpreation of terms used?
Or, is the graph really describing forces on the stick to achieve a dive?. That's more correlated to the data shown:
First table:
Stab incidence = 0 - Increasing stick forces in the PUSH direction are needed as the IAS increases to achieve a certain dive angle, 23,7 degrees.
Stab incidence = +1.5 (Aircraft Nose Down) - As the plane is trimmed nose down, less PUSH forces are needed on the stick for greater dive angles. A greater push force to achieve a 29,0 degrees angle than 26.0 degrees as the airspeed increases (Km/h).
Second table (gliding at idle) shows the same trends in forces.
DCS Normandy is really a great step forward from ED for us, the WWII old bird jockeys. Since I started flying the Bf109 in DCS I was very surprised by it's behavior in flight, the stabilizer trim seems simply wrong. I expect the current flight model to be corrected in some way to be a competitive aircraft in the WWII arena.
Thanks,
Mezzer
