Hatz Biplane Association

I'm going to CA to look at a Kelly D tomorrow, and was hoping for some info regarding the spar upgrade of which I have heard rumors.

Is the CB1 Spar the same as a Kelly D spar? Is the analysis performed on the CB1 relevant?

Does anyone have drawings or info on what the upgrade should look like?

Thanks, John Cadwell

Hi John,
Well, I do not have any experience with a Kelly-D and I'm no aeronautical engineer, but I would not think the CB-1 analysis could be applied to the Kelly-D. They are different airplanes that happen to share a common support organization. One key difference between the two is that the Hatz has a three piece top wing - left & right panels and a center section; the Kelly-D is a two piece wing - left & right panels attached at the cabanes (which are also different from the Hatz).

Perhaps someone here with more experience can shed some additional light.
Doug.

There has been an analysis done on the kelly-D---but a biplane cellule has to be analyzed in its entirety-- Top& bottom wings,
all the flying wires, and especially the N struts , as a true analysis is dependent on the "sharing" of the loads between all the members..
If you draw up a space frame of a biplane cell, apply some loads produced by the wings , and then try to solve the force
diagrams by simple triangulation --you come to a couple of points where the force is distributed by TWO struts---The
question is --How much in each strut. One of the first methods was by the theory of "least Work" which is what I used.

I have done an analysis on my K-D , but--I have mostly 7/16" flying wires (bought VERY cheap) and some old Piper wing struts
used for the N struts (same $ reason), and Doug Fir spars.

If you search the Hatz/K-D website I'm sure you could find the analysis done by Jurg Mueller (sp-??)

Jerry Wass