Thursday, July 5, 2018

Relative wind demonstrator keychain

We've all had our CFIs demonstrate maneuvers to us by puppeting a little model airplane. In fact, it's hard to find a flight school without a few little models lying around, often (with a strong sense of irony) some cool WWII fighters that the hapless students stand a snowball's chance in Hell of ever getting to fly in their lifetimes....

What these models miss is the most important thing -- and, as a reader of this blog, you probably already know what we're going to say it is. It's the relative wind!

To that end, we have created a little trinket that you can use to visualize your aerodynamic state as you puppet your maneuvers. Move the little arrow around to simulate different angles of attack and yaw, and move the arrow closer to the plane (i.e. appearing bigger from the viewpoint of the pilot) to simulate a higher indicated airspeed. This is, of course, precisely the metaphor around which the Airball display is built!

We're going to be giving these out at Oshkosh this year, so if you want one, be sure to find us and get yours!

The production line

To get these made, I 3D printed the parts on my Prusa i3 MK2S printer. I made tray after tray, using up a whole reel of yellow filament and a bunch of blue:

A few of the prints went sort of sideways, but that's part of the deal I guess:

Melissa and I then had a massive assembly party:

And the final result, a pile of almost 200 little doodads:

Tokki the whippet slept nearby. Poor guy has a hurt paw and has to wear the Cone of Shame:

Making your own

Each of these is made of a 2-piece arrow, an airplane, a keychain attachment and a little rubber band:

You first insert the keychain into the arrow body, and attach and secure a jump ring:

The hole in the body is large enough for the chain, but the jump ring won't fit, so that secures it. You then attach the body to the arrowhead with some cyanoacrylate glue and use the rubber band to secure the arrow to the airplane:

The keychain parts are from and are here, $7.49 for a pack of 100:

The STL files for printing the plastic parts are in this Google Drive folder:

Oshkosh 2018 airplane model

The filament is Hatchbox 1.75mm PLA, in the standard Blue and Yellow colors.

Hope to see you at Oshkosh!

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