Sine wave spar

[Konrad]

On the subject of triangulation.

The webs really aren't adding much as a sine wave spar. As Doc said much of the added benefit comes as a function of the sine wave amplitude. The undulation of 3/16" in minimal.

 

[jure]

another suggestion for the triangles:

 

[Konrad]

That’s a lot of work fitting the triangles under the spars. Other than a bit more glue area what do I gain for the added work?

 

[jure]

the anchoring of the triangles at a single point, without forming a quadrilateral shape.

 

[Konrad]

As there is some interest in this Tercel project I'll start a thread on the Tercel.
I think the point of the sine wave spar might be missed. The webs are not intended to make triangles. My simplification of the construction results in straight web segments.

 

[Wayne]

If you just knew someone with a laser cutter... LOL

 

[Hank GB Z]

Konrad,

Please be sure to post a link to the threads so we can follow along.

One detail I just noticed is you spaced the ribs out to simulate the sine wave. How did you arrive at the right spacing? And will you leave that ply carry through long or trim it down to fit the rib bay?

Hank

 

[Doc James Hammond]

Konrad,

Please be sure to post a link to the threads so we can follow along.

One detail I just noticed is you spaced the ribs out to simulate the sine wave. How did you arrive at the right spacing? And will you leave that ply carry through long or trim it down to fit the rib bay?

Hank

The correct spacing (Frequency) has to do with the natural frequency of the built model, but mostly the wings.

Its easy to work out accurately - if you have a few months and a Frontier 1102 petaFlop supercomputer in your closet that is. Longhand will turn your brain into a sinusoidal infinity loop.

Otherwise, don't worry - on a balsa model the same spacing as the ribs, or half that will work fine.

Oddly enough, when I tried to work it out (quick and dirty) for the MKI Redshift, I was happily surprised to find that the frequency was roughly 60mm peak to peak which is pretty close to the locally made corrugated glass fibre roofing panels. As an added bonus, the actual curve of the corrugations looks like it was derived from a real sinusoidal profile. Don't you just love it when a plan comes together...? By accident...?

Doc.

 

[Konrad]

Ok, moving the Tercel joke to another thread

Doc, Really, you and I know that this can be done with a slide rule! (Well, those of us with gray hair, sorry Doc).

Hank, I used the as supplied web width as the spacing for the ribs, a lot less work!

Wayne, Is it up and running? And how much will you charge for operator time? Sounds like a great project for a Friday build night!

 

[Doc James Hammond]

Grey hair? Konrad, why you young ...

I need a breadth of fresh hair it must be admitted...Haircut? Nah - mostly I just go for a nice wax 'n polish. Not many people get their skulls detailed...

Julia says its romantic - she can see the full moon every night...

Cheers,

Doc Scully.