Hatz Biplane Association

Looking at this picture seems the hole, circled in RED, brakes through the end of the spar.

Is this the way everyone has done it? .... just curious.

Blue skies,
Keri-Ann

On my Classic's top wings, the bolt holes on the front and rear spars are very close to the edge similar to your picture.

-Scott

Yes, Kerri-Ann that's right. It's exactly how mine worked out and how I've seen others.


Nick

The hole is drilled close to the end of the spar and then opened up because during assembly you need to put a bushing in there before putting the bolt in. The bushing prevents crushing the end of the spar between the two wing attach plates.
John Hanson HC-012

This is obviously a picture of our wing spar! We cut the edge of to clear the bolt, but it can be done eighter way...

Hans & Sam, H.C.#78, Switzerland

stearmoth wrote:This is obviously a picture of our wing spar! We cut the edge of to clear the bolt, but it can be done eighter way...

Hans & Sam, H.C.#78, Switzerland

Yes this is. Hope you do not mind me using it? I just did not see if one leaves it this way or does some other opening up of the hole. But John Hanson HC-012 explain it, thanks.

Why I was asking, I am doing a 3D Build of the entire plane. I like to check fits and its sort of a per-build in my head, so when building, its like the building a 2nd plane .... make since?

Hi Kerri-Ann!

Please don't misunderstand me! You can use everything free you find on our homepage, of course!!! I just noticed, that this was our spar picture...
Anyway, I find it doesn't matter if you cut an edge off or just leave it that way! Any thoughts?

Kind regards
Hans

P.s. This is great if you model the Hatz in 3D -- That's a task!

Hi Hans,

I just thought that I should have asked permission first and felt I did something that may have upset you by posting your work. Thanks for the use and permission. Understanding a lot about the build from your excellent web site, great detailed pictures. .... any more to post?

About the bolt /spar breakout, I was just curious because a bolt breaking through the end of a spar where a fitting is attached is a place that a crack could develop over time longitudinal. We have had this happen in an Aercona Chief we owned.

As John stated there is a bushing between the two fittings, so I would tend to open up the area to the diameter of the bolt and install an aluminum bushing there. Or move the bolt hole in the fitting back to a minimum of two bolt diameters from the spar end.

Really need to study the plans more, just getting to the wing spar 3D Model. Will post more drawings as I go.

This is so much fun!

BTW, Love your plane Hans. What inspiration for all of us. Are you starting to cover her yet?

Blue skies,
Keri-Ann

Hi Kerri-Ann and all,

The mentionned bushing concerns me: we didn't find a hint on the Makelan drawings to add such a bushing between the wing spar and centersection fittings (on the lower wings there is one welded to the longeron). What other's do? Do the CB-1 plans ask for such a busching or better called distance tubing?

It is very motivating to follow and energise the discussion between all of us, and we don't see this under a competition aspect. In contrary, we are delighted if others leave the path and create a "new" version of a well proved and beautiful design, which the base CB-1 is! Among the most significant changes have been created by Billy Dawson, Mark Marino and Mehlin Smith, just to name the common best known. We ourself tried to continue the path of Mehlin and adopted the newly built Rotec engine in order to have a vintage looking biplane hopefully without the risks of an old radial engine where spare parts are lacking and less engine rebuilders are offering the service of overhoul and old engine....

So keep up the discussion and we are eager to see other new versions.

Kind regards
Hans & Sam, H.C,#78, Switzerland

P.S. We are still awaiting our static load test, which is delayed to mid January (too busy schedule of the authorities). Then we are now ordering the Poly Fiber materials from the Belgian agency (at almost twice the US cost) because it is so difficult and expensive to ship solvents overseas. However, based on what we have seen in your country, we feel that with Poly Fiber we will be able to reach what we expect.

Hans & Sam, Keri Ann and all,
I had a in depth discussion with my DAR about this very subject while building the top wings. I was very concerned that the hole being so close to the spar edge could eventually cause a crack to develop. He assured me that with the addition of the doublers that the load is transfered through the entire spar fitting assembly and that no movement will occur to set up a crack even with the hole so close to the spar end. I did not install any bushings and proceeded as per plans. Scott used another method for his construction which can be viewed through his website that may be of interest to others as well. I'm attaching a picture of my spar that I had sent to my DAR for his approval before I proceeded with drilling the holes.