Hatz Biplane Association

I’m unclear how this is going to work.

1: The plans show the cockpit outline tubing welded to the longerons and not the square tubing that the aluminum cowl bolts to. It seems to me that when wrapping the aluminum over the fuselage top, it won’t fair along those tubes. Is that correct?

2: How is the aluminum sheeting secured around the cockpit openings? I’m thinking it’s laced to the steel tube frame when you put the cockpit combing on?

Any input would be appreciated. This is the stuff that keeps me up at night!

Hi Beech D
When I welded in cockpit support tubing under the aluminum just inside of the cut out holes I used 1/2" PIPE INSULATION AND LEATHER COVERING FOR COMBING then laced this to the aluminum 2" spacing with parachute cord. This tightens everything. I hope this is of some help.
Steve HC0162

That’s what I figured I’d do. So you welded in the tubes to be fair with the aluminum. Gotcha. The plans must be off. I’m sure this will become clearer when I get to that stage.
Thanks
Doug D

Hello Beach D
I forgot about answering your second question about where to weld the opening supports to the upper longerons. Mine is a classic so there is lots of clearance from the skin. I"m helping a frend build building a cb1 which will require this to conform closely to the skin. Also he want"s to add a passenger door to compliment things. Lotsa fun.
Regards Steve HC0162

Thanks Steve,
Appreciate the feedback. Honing to put a door on mine as well.

Timely topic. I was just starting on the cockpit cowling.

For Doug's first question, the pictures from the CD show that the plans are probably correct. The cockpit outline support is attached to the longeron and not the square tubing. It looks like the only support it gives it to the actual cockpit opening and not up from the longerons. I was thinking of attaching the cockpit outline tubing to the square tubing and form it to fit the aluminum cowling. Probably not required as the support is needed for the opening and not along the sides.

For the second question, I'll probably screw the aluminum cockpit cowling opening to the metal outline support. I drilled holes right through the square tubing and welded anchor nuts to the bottom side of the tubing rather than using nutserts to attach the aluminum cowling. This was a suggestion from a mechanic. Just about everybody I talked to hated those $%#*& nutserts. I'll do the same for the cockpit hole. The screws and anchor nuts for the cockpit holes will be covered by the leather and padding.
If you check out Jeff Orear's EAA Builders log, he didn't bother with the metal cockpit opening supports. He formed an aluminum tube to the cockpit openings. It definitely makes for a clean looking cockpit opening. Jeff, I hope you don't mind me posting your picture here.

No problem Murray. Just good to see someone actually looks at my site!

I would add that I also have aluminum angles that will be riveted to the cockpit skin to give it more stiffness. All of this is from the fertile mind of Carlo Chillar and his award winning Classic. Gotta come clean. I’m not that smart.

Thanks! I did see Jeff's post and thought that was a way I didnt think of. Looks legit. I've also seen people form the upper cowl and build the reinforcement at that point. I will go back and review Macklands pics and what I took at Oshkosh and get a better feel. Bit of a ways off but for that but going to be at that stage of the build by Spring. And it makes me sleep better knowing I have a clear understanding of the concept.