LSA Spar attach questions

[Grum.man]

With it being cold out and spending a lot of time at home I started adding some of the LSA parts to Solidworks. I am not ready to start building just yet but this has proven invaluable to me for visualizing how things go together and to strategize how to accurately construct it. Other motives include the amount of work shortening each wing bay by 20" would make, as well as visualizing how it would look with a radial engine. When I get started I will likely buy the spars and ribs from the bearhawk store as the price vs labor and tooling seems like a good tradeoff.

With all that said my efforts have raised a few questions that will bug me if I don't get some answers. At the spar attachment I designed the brackets by pulling dimensions from the drawings as best I could. The parts don't match up perfectly. I don't think it would cause an issue but I was wondering if anyone else' looked like this in the first photo?

Second thing I noticed is the small gap between left by the spar material thickness. Do others fill this in with a scrap piece of spar thickness aluminum or is the gap fine?

The attachment holes on the component drawings scale to about 3/16". In the wing attachment drawings the front spar attachment measures approximately 5/16". Is that the final size that the holes should all be once the alignment is verified?

And lastly is a little teaser of what one would look like with a round cowling. Also experimenting with a few more stringers to round the shape out a little.

[BTAZ]

I believe the "small gap" has been addressed before. The spar web goes all the way out and is profiled to match the attach brackets.

When I built mine, I made the brackets by tracing per the plan outlines, then put them on the spar and contoured the spar web to match the brackets.

[Grum.man]

I believe the "small gap" has been addressed before. The spar web goes all the way out and is profiled to match the attach brackets.

When I built mine, I made the brackets by tracing per the plan outlines, then put them on the spar and contoured the spar web to match the brackets.

After I posted the question I found an old build log I had saved that showed the spar web between the brackets. So if you traced the drawing I guess the profile of your brackets didn't match either?

[BTAZ]

It has been a few years but I don't remember the front/rear pieces being mismatched.

Maybe Mark or someone with more recent experience can clarify

[PropMan]

And lastly is a little teaser of what one would look like with a round cowling. Also experimenting with a few more stringers to round the shape out a little.

[/QUOTE]

A Verner 7U on there would be pretty cool!

[Grum.man]

And lastly is a little teaser of what one would look like with a round cowling. Also experimenting with a few more stringers to round the shape out a little.

A Verner 7U on there would be pretty cool![/QUOTE]

That’s the engine I based my model on. The cowl shown is the boot cowl, the engine would sit in front of it. The diameter is what the 7u measures. I tweaked the firewall design to have a smoother transition from round cowl to the fuselage.

[sjt]

s.jpg
c web channel extends all the way under attach angle plates. Trim after riveting attach plates to web.

The web c-channels are different lengths. I think the best way to make the spar is to start by laying out the cap strips at the center web splice . The c-web will then have extra material under the attach angle.

It would require much more effort to lay out the attach angle and web perfectly, and then have to trim the c-web at the splice in the correct location. The capstrip rivet holes might not be far enough from the cut end if done that way.

Bob's drawing dimensions the attach hole as a reference point to the center web splice. Just make the part reverse of drawing layout. Start with the nice factory made squared off end that is at the center splice and assume that you will trim off at the attach angle plate with a trim router bit. All that is required is to position the cap strips rivet hole with the 9/16 offset from the c-web end.
b.jpg

[PropMan]

A Verner 7U on there would be pretty cool!

That’s the engine I based my model on. The cowl shown is the boot cowl, the engine would sit in front of it. The diameter is what the 7u measures. I tweaked the firewall design to have a smoother transition from round cowl to the fuselage. [/QUOTE]

I built a Legal Eagle with the Verner 3V, Love the radial sound, thought about the 7 on my LSA but i want to get it do quickly so going with the O200