2011-02-18

X-Plane utility competition lineage

This is a history which shows the progress up to my previous post. First is my DH 84 simply converted into a KZ IV-lookalike. Should have had NACA 23018 airfoils, but I gave it 23016 and 23012 instead. Turned out to be overweight and with control issues. Next I tried with four Pobjoy Niagaras in order to get more power. Controllability was worse, so I gave that up. These were both fitted with simple flaps.


I then switched to a high wing, but didn't want to move the engines up, so I moved them forward a bit, Do 28-style. This one flew pretty well, but had much too high stall speed. Should also have had NACA 23018 airfoil if it wanted to be Do 28-like.

Next, in order to save weight a single all moving vertical tail. And with a more modern airfoil than a 0006, NACA 66.009/66.006 which has lower drag. From here on, all designs have fixed leading edge slats. I'm trying to have two flap schedules, one with more deflection right behind the engine and outer flaps which only are used on landing.

As the general layout was workable, I tried with new wing airfoils, NACA 4418. And I also switched to NACA 2412 for the propeller foils. Fixed pitch propeller. More radically, I tried Junkers flaperons. They work very well in roll control at low speed, but not so much as flaps. More importantly, here is when I decide on nose gear.

A bit of re-work on the wing to give less drag in the centre section looks good, but is more complicated than needed. Next iteration, which you saw in the previous post, adds a wing behind the engines to get some powered lift. Not sure if that's a good idea.

If you take a good look, you can see in all but the second image traces of one of the aerodynamic tricks I'm using to get better landing performance.

The other is the lack of inverted airfoils, so instead of a symmetrical foil for the stabiliser I have a lifting one with dihedral 180 degrees, no elevators instead ailerons which move with pitch (and not with roll), but opposite.

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