For Fenix:
You mentioned that you started with a flyable RV-4 and are preparing a new tapered wing to replace the original. What a great opportunity to compare the two.
The predrilled spars were not available when I built my wing and I cannot simply plug a new wing into the existing match drilled centre-section. I assume that you have solved the problem of transferring the bolt hole patterns to the new spar. As I recall they were drilled undersized and then reamed to fit.
What was the gross weight of your RV and with all of the new fuel available, what weight are you planning for the new configuration. You mentioned the capacity earlier but perhaps you plan to fly long distance solo.
Edit:
I just re-read post 23. This new wing is something you are trying out with an eye to a custom fuselage. The original gross weight for the RV-4 was 1500 lb., increasing that to 1868 lb. is rather ambitious. The original fuel capacity was 32 gallons, the additional 40 gallons that you are planning amount to 240 lb.. You seem to be allowing for additional weight growth. Do you have a weight comparison for the old and new wing panels?
For the sake of flying qualities, the two wings can be flight tested at the same flying weight, lots to learn there.
Yes it was the opportunity for a "head to head" comparison that really piqued my interest. The engineer who worked with me on this was also interested in the ability to make this direct comparison. If it had not been for the opportunity to compare the two I don't think the engineer would have been curious enough to take on this job.
Yes the issue of building a new wing that would fit in place of the original one was a point of real concern given the "hand made" nature of most homebuilts, to include the RV4. And yes, they are all joined with close tolerance bolts as you described. I spoke several times with Wayne of Phlogiston products (who made a lot of the spar components and a lot of completed spars for the RV4 specifically) about this challenge and how it could be tackled. He was very helpful, an all out "good guy" and gave me a lot of tips, techniques and advice for how to make an accurate reproduction of the original spar.
Of course it involved taking the wings off of my plane to make patterns, not only of the main spars but also of anything else I thought might be relevant, most notably the relative positions of the main and rear spar as these also change a bit from plane to plane. Taking out all those (I think there are 28) close tolerance bolts in a somewhat hard to reach place, and putting them back in again was not much fun. But in about 2 weekends work I had them off and back on again with a nice set of patterns. Soon I get to do it all over again, and then I will know how well the new wings fit. I may be unpleasantly surprised, but I'm pretty confident they will line up well after taking all of Wayne's advice.
In regard to your question about the weight limits:
As I recall the gross weight for the RV4 is 1500 LBS. My original empty weight as I recall is 1050. Yes this wing is engineered for considerably more weight than the 1500 Lbs of the RV4. Some of the RV4's limits are due to its wing, which in my case will be changed. Of course there are also limits of the fuselage (of which I have not analyzed) and most notably the landing gear. My original plan was to fly this wing on my RV-4 and, if I liked the way it behaved, to then build a new airplane for this wing and return the RV4 to its original condition. The additional weight capability of the tapered wing is intended to be used on the "next plane". I don't intend to fly the RV4 beyond its stated design limits. Yes, as you stated, you can fly further solo because you can put more fuel.
I think I stated above (or maybe only intended to) that the plane I had in mind for this wing was something very similar to what is now the F4 Raider. So instead of designing a new fuselage for this wing I may just build the F4 design and put a tapered wing on it. If I do that this wing will not work because the F4 is wider than an RV4 (the plane I would have scratch built for it would not have been wider). So this wing may end up staying on my RV4 forever, yes with more weight capacity than can be used on that fuselage. But now that I have all the fixtures and techniques sorted out I believe I can build another set of wings quicker than I can design and scratch build a fuselage. I began to take notes along the way of things I learned in the building of the first wing so I would not forget them before building the second wing. Having all the fixtures and techniques and tricks sorted out I built the second wing from scratch in about 225 hours. I have had the analysis done for extending the center portion of this wing by 4" for use on the F4 so that is likely what will follow if I like the characteristics of this wing. If I go this route I will have to comply with the limitations of the F4 of course, but IIRC the gross weight limit of the F4 is 1850, very close to the 1868 I designed for.
The final decision of whether I use the F4 design or complete a design of my own fuselage will not be made until flight testing is done. Due to the washout I put in the wing the "average angle of incidence" is a bit less as it relates to the fuselage than it is on the original RV4. This may result in the plane flying somewhat "nose up" to get the required "average angle of attack" for level flight. The engineer was particularly curious about the outcome of this condition. We don't think it will make much difference (but again this design was subject only to a structural analysis, not a performance analysis or stability analysis) but if it turns out the plane does fly "nose up" with this wing compared to the original wing the fix will be to change the angle of incidence when mounting the wing to the fuselage. If this turns out to be needed I will not build the tapered wing F4 but instead do a new fuselage design as I believe the incidence on the F4 is that same as on an RV4.
As far as a weight comparison of the rectangular vs tapered wing panels: No actually I have not weighed the new wing panels yet. They have not yet been fully assembled with flap, aileron, and both tanks all on the wing at the same time so I never took occasion to weigh an assembly. Yes, I could simply weigh the components individually and arrive at the unpainted wing weight but it never dawned on me to do that and now I am not on the same continent as my project so sadly cannot provide a wing weight. However I will post that info when it is available and then later the performance changes I measure from flight testing.
I hope that addresses your questions in a meaningful fashion, but if you have more, feel free to ask, I'll do my best with the info I currently have access to.