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Another airfile question...

Rami

Rami

Administrator
Staff member
Hey guys.

I want to take a stab at redoing the airfile for the Dewoitine D.376. I looked for aircraft with similar performance, and the PZL P-11 aircraft is a very close match.

However...the PZL P-11 is a gull-wing and the Dewoitine D.376 is a high-wing parasol type. Does that make a major difference in the airfile?
 
Negative...the flight dynamics module doesn't recognize unconventional wing designs per se, only wingspan, wing area, dihedral, twist, chord, drag factor and incidence. You can play around with all of these to tweak out performance disparities between the two designs. More to the point, given that the low gull wing design has a greater degree of dihedral over the parasol, which generally has none, there is some room there for a noticeable difference in roll rate or aileron effectiveness.
 
Reply...

Bearcat241,

Okay, cool. So as a general rule, which numbers will I be focusing on the most? (Chord, Twist, dilhedral) And going from a gull wing to a flat wing, which way would the numbers be trending?
 
For a gull wing, mainly dilhedral, with a minor emphasis on increasing the chord. The opposite for the straight wing.
 
Rami said:
...And going from a gull wing to a flat wing, which way would the numbers be trending?
Click to expand...

Sorry Rami, i was in a little rush at the time and only answered the first question. As for adjusting the numbers, for these two AC there's basically nothing much you want to. I should have looked closer at the PZL before replying. The PZL's high-mounted gull wing and the Dewoitine's high-mounted parasol wing have very similar constructs from mid to outer wing and only major difference is in the fact that the PZL's wings are fuselage mounted at the roots, with additional fuselage support struts, whereas the Dewoitine's are mounted to its fuselage strictly by wires and struts. This makes the Dewoitine's design inherently weaker for hard maneuvering and susceptible to greater drag.

But overall, between the two there's just not enough there to warrant drastic changes in the numbers, except maybe in the G limits section of record 1101. All of the other factors - wingspan, wing area, dihedral, twist, chord, drag factor and incidence - i would suggest just leaving as is.
 
Reply...

Bearcat,

Thanks for the detailed explanation, I really appreciate it!
 
Reply...

Bearcat,

Success! I tested her both in combat and free flight, and with the correct weight and engine data, and using the PZL P-11 airfile as a base, she handles well and "feels" pretty authentic, much better than before. I've got the max speed set about perfectly.

The only other thing that still mystifies me is that she starts above the runway, then settles onto it when she loads.

I really appreciate the guidance here....
 
Rami said:
...The only other thing that still mystifies me is that she starts above the runway, then settles onto it when she loads.
Click to expand...

It may take some work get it just right, but you'll need to adjust the static_cg_height in the contact points of the aircraft.cfg. You do this by pausing as the cockpit view loads - don't let the loading finish - and go to external view. Note the distance between the ground and the wheels (in feet). Minimize the screen, open the aircraft.cfg and decrease the static height by so much and save, but keep the cfg open on screen. Maximize the sim window, reload the model (Alt+A+Enter) and freeze it again before the loading finishes. Check the wheels-to-ground distance again and repeat until satisfied. Once you get the main wheels contacted properly, you may need to adjust the static pitch to get the tailwheel down as well.
 
Reply...

Bearcat,

Actually, it wasn't terribly difficult at all. However, with the Dewoitine 376, I spoke too soon. The aircraft has the "PZL disease" since swapping out the airfile. When you start the engine, the aircraft surges forward, and you can actually take off without increasing the throttle. However, the engine and prop data appear correct...:dizzy:
 
Not sure which model you're into, but if you have a record 505 in the air file, go to Propeller Start Delay and lower it into the range of 15-25 --- 25 being the strongest.
 
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