DC-3 (Again)

[wunwinglow]

I seem to remember they flush-rivetted a Spitfire, test-flew it, then progressively glued split peas over it, in different locations, to see there flush mattered and where it didn't. Might be an apocryphal story...

Tim

[Leif Ohlsson]

OK, I'm glad to admit it - you never get too old to learn. Could not believe a DC3 really looked like that close up, even though I studied the photos Gil provided earlier closely. Just didn't register. Too much looking out the window of contemporary commercial jet airliners prejudiced me, I guess (although it hasn't been that many occassions).

Leif

[Gil]

Thanks for the huzzahs. I am actually beginning to understand how to use Flamingo, Rhino's advanced renderer (now that's scary). I find that my usual problem is not reading the next paragraph, so to speak, for the explanation. Doing so saves so much time..., (Total Attention Deficit Disorder in action I am sure).

Always remember that the render engine needs surfaces to render. A line or point will not render because it has by definition zero surface area. It can be "shown" in the rendered image meaning that it cannot be represented as an "illuminated object" and will not be smoothed or anti-aliased by the render engine. Rhino is great at very small surface detail and Flamingo faithfully renders it. The reason for using a rectangular cross section surface is to insure that it's surface is well above the surrounding surface at all points. A single surface parallel with the larger surface will tend to "melt" in and out on curved surfaces causing unwanted artifacts in the rendered image. Below is a render using the Rhino Render engine of the same geometry as used earlier in thread.



I think what Tim was referring to was an attempt to prevent separation of the laminar airflow on the Spitfire. The split peas acting as turbulators. Any of you who have dabbled in high performance gliders are probably familiar with the following explanation:

http://www.mh-aerotools.de/airfoils/turbulat.htm

+Gil

[maurice]

Tim
Not an apocryphal story. Once the boundary layer has transitioned to turbulent flow you might as well save on production costs and time and peeling half peas off in stages showed where flush riveting was necessary and where effort could be saved.
Fully equipped with peas the Spit lost 22 mph in top speed.

Shrike
And for the same reason that golf balls have dimples.

Gil

No, turbulators explain Shrike's point and why golf balls have dimples but that was not the purpose of the peas test with the Spit. That was intended to establish the areas that retained laminar flow.
Models and golf balls are operating in a totally different range of Reynolds numbers to full size aircraft and, as in this case, the relative importance of some effects can change dramatically between small and large flying objects.

[Gil]

The rivets from the earlier experiment were applied to projected rivet lines on the nacelle skin using the "array along curve" command in Rhino. Transverse ring bands were done first providing correctly rotated rivets for the horizontal rivet lines. Again these were stored as a separate layer in Rhino. Apologies again for the low resolution HDRI dome image.

Beginning to look like a real aircraft skin...,

+Gil

[Leif Ohlsson]

Apologies again for the low resolution HDRI dome image

No apologies necessary for this, Gil - it looks astounding indeed!

Leif

[John Bowden]

Gil it's beautiful.............but the polished mirror finish looks more at home on a Reno Mustang rather than a Gooney Bird.

But it would look fantastic in Delta Air Line livery.

john

[Gharbad]

There's a DC-3 on the cover of my local airport's magazine.
It's a very nice looking plane.

[Gil]

Glad you guys like it. I'm kind of partial to it for all the above reasons...,

Many of the DC-3s were only painted to accent the aircrafts aluminum art form when first put into service by the airlines. That's the look I'm after. Down the line from here I'll apply a paint pattern to the surface for one of the early adopting airlines, probably do the City of San Francisco, United Airlines Mailiner Service. American DSL's are also prime candidates (have to add the sleeper widows to the fuselage).

Rhino's rendering abilities have been one of it's more maligned attributes but with the release of version 4 and Flamingo version 2 McNeel and Associates is catching up fast. I seem to be getting happier all the time with it...,

I'm taking a small break to do something else for the next several days...,

+Gil

[Gil]

Guess who got a new render/shader?

+Gil