Spar cuttout and LG bulkheads

[Phil Kriley]

I trial-fit the wood pieces (LXY and LDX or somesuch?...plans are at home...) at the rear of the side, and neither the angles nor the lengths are exact. I adjusted the forward piece so that the rear of it is parallel to the rear of the fuselage side at 5.5", and the wide wood is 8.7" from the bottom of the upper longeron, and the two pieces meet nicely.

 

But my question is: How do you know exactly where the front wood should go - and does it matter? The forward bottom of it is supposed to be 16.3" from the rear - is this critical? If so, then I will have to cut new wood because mine are too short. If my forward piece fits the front of the wide piece and the wide piece overhangs the rear of the side exactly .5", then am I good to go?

 

I cut the wood exactly per the plans, but could not make them fit per the drawings.

[Jon Matcho]

How do you know exactly where the front wood should go - and does it matter? The forward bottom of it is supposed to be 16.3" from the rear - is this critical?

The 5.5" and 8.7" dimensions are critical, with the 16.3" dimension setting the angle of LWX.

 

I adjusted the forward piece so that the rear of it is parallel to the rear of the fuselage side at 5.5", and the wide wood is 8.7" from the bottom of the upper longeron, and the two pieces meet nicely.

Sounds good -- make sure you're checking for perpendicular to the upper longeron (should be same as "parallel to the rear of the fuselage side"). The angle is important, which is what the 16.3" measurement does. If you're you're close, you're probably fine based on your definition of 'close'.

 

Check out how Bernard Siu addressed it on his web site.

 

I recall the same dilemma and just moved on. There's definitely more guidance that could be added to the plans in that area, but... close enough I think. I'll let you know soon how my LG bulkheads align to LWX and LWY -- that's my next step.

[Phil Kriley]

I guess I'd better cut longer pieces then, because if I get the angle right, the front piece doesn't touch the lower longeron doubler - it comes up about 3/16" short - almost 1/4". The good news is both sides are identical.

 

What we need is to draw an extended line from the 16.3" location to the corresponding endpoint on the upper longeron, then place the front piece on this line and cut the wide piece to fit.

 

So if I understand - the 5.5" and 8.7" and the 16.3" are the critical measurements. The wide piece needs to hang off the back AT LEAST .5", but it can be more...? That being the case, the angles and lengths in the plans flat out don't work. I'm thinking out loud now: Maybe if I draw an extended line from my front piece to the lower longeron and it hits at 16.3", then I know I have the angle correct, and I can just flox the gap or cut a filler piece to make the front piece meet the lower longeron doubler...? Whadaya think?

[Jon Matcho]

So if I understand - the 5.5" and 8.7" and the 16.3" are the critical measurements.

You do understand!

 

The wide piece needs to hang off the back AT LEAST .5", but it can be more...?

Correct... it can be more, which you can just cut to 0.5" when it comes time to fitting your temporary firewall.

 

That being the case, the angles and lengths in the plans flat out don't work.

In this case, I think you're right. You now have me wondering what I did exactly to address the issue, and I'm going to verify tonight. I'll let you know.

 

I'm thinking out loud now: Maybe if I draw an extended line from my front piece to the lower longeron and it hits at 16.3", then I know I have the angle correct, and I can just flox the gap or cut a filler piece to make the front piece meet the lower longeron doubler...? Whadaya think?

Sounds like a fine idea. Check the link to Bernard Siu's web site above (I must have edited while you were reading). He writes about doing the exact same thing.

[Phil Kriley]

You do understand!

 

 

Sounds like a fine idea. Check the link to Bernard Siu's web site above (I must have edited while you were reading). He writes about doing the exact same thing.

Yep - I went and visited his site and he did what I proposed - man that makes me feel better! I don't know about you, but I'm in awe of his and Wayne's craftsmanship! My project looks good, but their's looks like fine furniture!

[Jon Matcho]

I don't know about you, but I'm in awe of his and Wayne's craftsmanship! My project looks good, but their's looks like fine furniture!

I know what you mean. Bernard's work looks very good, and has been praised by a builder-flyer as "exceptional" (or a similar word).

 

I can see how people can allow themselves to have "rough" planes, as well as how people can have "immaculate" planes. I just want a "good" plane that is well-built, has no sharp edges or burrs, and flies very well. I don't want it to take any longer than it needs to, and I am definitely not doing this to make a show plane. Still, I'm doing my best to be neat while trying not to develop another OCD in the process.

 

Sooo... keep up the GOOD work!

[Kraig]

Phil,

Another site to keep as a reference is Rick Maddy's. He has great photo's and descriptions, and it will really answer many questions as you go along. Consider his and Wayne Hicks as your bible, I will read up on both their sites many times before and then many times during each step. Has saved my bacon too many times to remember.

 

Kraig

(Starting chapter 10)

[Phil Kriley]

Thanks Kraig! Will do!

[Jon Matcho]

So if I understand - the 5.5" and 8.7" and the 16.3" are the critical measurements.

My 16.3" was probably ~15.9", and you can see the resulting dilemma here.