Ideas for Vert Stabilizer Airfoil

Dear All,

I am sure someone has a great idea for creating a vertical stabilizer fin that is way easier than what I have been doing. I have been drawing airfoil sections in 2D and then stitching them together.

Attached is the model I am making, with the vertical stabilizer shown in 2D.

Note: I have not done any stability analysis on this model. Once I figure out how to model the aerodynamic surfaces, I will work on stability.

I would be very happy with any advice.

Best to all,

Chip
Robin Body 3.skp (2.9 MB)

Cool! If you want a simple constant taper to the foil shape, draw an end of it. Extrude it to length, and scale one end to the smaller dimensions. In the case of your vertical stab that would work for most of it. For the root and tip ends with the curved leading and/or trailing edges you could extrude a little, scale a little, extrude a little, scale a little, …

Alternatively you could model the foil cross sections at various stations along the span and then use Curviloft to create the surfaces.

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Brill! I forget about extensions. Duh.

Thanks,

Tom

Hi Tom,

You’re welcome.

FWIW, I did a little bit of your stab.


For the main length I drew a foil cross section at the bottom of the rudder and extruded it up. Then I scaled the span from the front to get the sweep along the leading edge. I didn’t scale the chord over that length but I figured that would be done at least above the rudder. Instead of Curviloft for the lower part, I used Extrude Edges by Rails from TIG’s Extrusion Tools (Sketchucation). I did the part I did in two stages. On the left you can see there the foil sections are. In front of the middle stab you can see the two stages. They got flipped/copied to make the starboard side. The groups that resulted from EEbyR operations were exploded to combine with the upper part of the geometry and made into a solid component. I split out the rudder with Eneroth Solid Tools. I figure the leading edge where the rudder meets the rear window on the “fuselage” can be modeled vertically. The stab can then be trimmed to the angle of the window.

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Well, I couldn’t stop.

I set up the top section like this so the top edge also has rounded end.

The last of the root end was done with a single operation of EEbyR. They were added to the existing geometry to make a solid component. And then the bottom was cut to match the slope at the rear of the fuselage.

FWIW, this could be modeled in fewer steps than I show I did it this way to be able to see how the surfaces were createdusing different options. Breaking it up made it easier to control.

With it in place I’m not too sure of the junction. Maybe it ought to flare a bit at that point.

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Not to change the subject too much, but is that a 1986 Rabbit with the mouse fur seats? Those are boss!

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Sorry to disappoint, but that is a Reliant Robin, circa early 70s. It probably came with bead covered seats.

The Top Gear guys (aka Grand Tour guys) tried to launch one into not even near orbit. This is going to be an attempt to launch a model sized version of their project.

Dave, Thanks for figuring out the top of the fin for me! Here is where I was at, before Dave. Always, before Dave.

Robin Flying Body.skp (3.3 MB)

Best to all,

Chipperoony

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I was thinking it was a Robin. I was thinking of " When Robin’s blue chariot inverted be, three wheels in the sky, … :stuck_out_tongue_closed_eyes:

Good work on the fin. Just need to make it all solid. :wink:

And that’s the tale of the ill-fated flight of the Reliant Robin. I pictured it cornering better in the air than on land. But I guess it’s nose down either way. Those bead deals can be pretty comfy too (if you don’t have mouse fur).

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