Hatz Biplane Association

Hi Classic builders,
There were some issues with Makelan drawing errors, we read about, but may have forgotten.... Anyway, yesterday we have got one in our necks:

When we first mounted an upper wing panel to the center section, we discoverd an issue! Fact is, that the rib of the outer panel is lieing 1/4" higher that the center section rib! While checking for the reason, we discovered that there is a mistake on the page 4 drawing!!!! The 1" vertical distance of the wing mounting bracket hole (on center section) is measured from the bottom of the spar rather than from the bottom of the center section floor. The number should read: 3/4" and not 1"! . We are not sure, if this issue has been posted earlier - We thought, but couldn't find a post. Anyway, the easiest thing will be to make new spar brackets with new positioned mounting holes for the wing panels as our center section is already finished. Othervise we would to tear away the top leading edge plywood panel and make all new designed sheet metal brackets, which exactly match the drilled spar holes.
Any better ideas?

We will inform Jeff Shoemake about this drawing error.

Sometimes one gets a draw back, but we are seeing land and put grease in our hands...

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

For those that have not reached this point. I only drilled the holes in the center section brackets. Then after the upper wings were built. I joined the wings with the center section -got my alignment. maked the holes in the wing and then drilled the holes under size and reamed to size. There are sim errors in the lower wings and I learned from this. Note you can use a very short section of a pencil held by neddle nose pliers to mark your holes.

Posted by Michael fly in 2011
Jan, 2003 to ?? 2011
N838MM

Thank you for alerting us to this dimension problem. However, I'm still not quite sure of how to solve it. I had my fittings water jetted with pin holes located as specified in the drawing. Can I just move the fitting down 1/4" so that the landing wire and reference holes are even with the center section bottom? Or do I need to relocate the wing attach hole on the center section fittings? At the stage I am at, I cannot tell if lowering the entire fitting will put the cabane, roll wire, and flying wire holes in proper position. Looking at page 4 of the drawings, it seems the reference hole and wing attach hole should be lined up with the bottom of the spar and therefore. I would need to relocate the wing attach hole, not the entire fitting. I have not drilled the center section spars yet, so once I am sure of the solution, I'll probably have the cs spar fittings remade.

Thanks

JD

I'm just about ready to plywood skin the leading edge of the top right wing and did a final check for alignment today and discovered the exact same problem. I haven't attached the center section skin yet so I'm planning on building all 8 center section spar fittings. My fitting are about 3/4 of a bolt hole off making the wing too high to match the center section. Can anyone input as to if it would be a good idea or not to weld closed that one hole then drill undersized then ream to size? Any input will be greating appreciated as I'm leaning toward just building new spar fittings.

Ron

As I'm about to assemble my centre section for the second time, I'd also be very interested in hearing how others have dealt with this.
Guys?

Nick

Hi guys,

We checked the drawings again and here is our proposal.

Look at the center section:
We think, that the position of the brackets is correc t, however, the hole for the wing bracket bolts sits 1/4" too high. We would not recommand to place the brackets 1/4" lower as then the holes for the cabane struts and the landing and roll wires sits too low (the brackets are protruding to much in the airstream). In this case, we would redo the brackets. This can be done also if the center section spars are already drilled. It is possible to absolutely duplicate the bracket spar holes to match the holes absolutely congruent!

Look at the top wing panel:

If the spar bracket holes are not drilled yet, we would suggest to mark and drill those holes for both front and rear spar brackets 1/4" higher. As we already drilled those, we are going to laser cut new brackets and relocate the wing connecting hole 1/4" higher.

We will be duplicating those brackets with an absolute match of the spar holes. If somebody is interested, we can send DXF files of our modiufied brackets.

We still haven't approached Jeff on this issue, but will do.

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

Hans and Sam, that's a beautiful looking aeroplane you have there.

I found a discussion in the archive that shows the exact problem you're talking about.
http://www.hatzbiplane.com/dcforum/DCForumID3/139.html
There are many other plans errors in there too. Maybe this discussion should be brought out into this forum so this information is not lost.

Nick

Nick wrote:Hans and Sam, that's a beautiful looking aeroplane you have there.

I found a discussion in the archive that shows the exact problem you're talking about.
http://www.hatzbiplane.com/dcforum/DCForumID3/139.html
There are many other plans errors in there too. Maybe this discussion should be brought out into this forum so this information is not lost.

Nick

FYI, The information from that thread has been brought into the "sticky" post called "Hatz Plans Discrepancies" at the top of the Hatz Classic forum.

Great idea, Doug. We can dig out all the discrepancies and get them in there for future builders.

Nick

As far as I can tell, on the right hand side of sheet #10 there is a correct depiction of the center-section to wing connection.
While that part of the sheet has no dimensions printed on it, it is 1:2 scale, and the details of the connection (end ribs, center section spar (without the bottom of the center section nor the fuel tank) are clear.
I encourage those who have encountered the problem to say whether I am right or wrong.