Hatz Biplane Association

I am a new Hatz Biplane Association member and just bought a CB-1 project and I'm thinking of making a few changes, (1) I would like to use a Cont. 0-300 engine (2) Cessna 170-B spring gear (3) cut and lower the upper left longeron for the front cockpit . My project already has a 10" longer fuselage and the upper wings have been extended 12" each. Any thoughts on this ?

Thanks, Rick_k23

O-300 powered Hatzes exist, I was looking at one online before I found the one (O-290 powered) that I bought.

I'm not so crazy about the spring gear, it would look wrong and require redesign of the fuselage in that area.

Lowering the longerons might be OK, but you'd want to do some careful structural analysis.

Thanks Dana,Just thinking about the spring gear, I like that it would give about 12" wider stance and less drag but it does change the look to a more sporty plane. Do you know if any one has build pictures of lowering the longeron? And going over my plans I see that I don't have any drawings of the wings. Do you know if I can get them without buying a new set?
thanks Rick

I think some have have designed structure to interrupt the longeron at the front cockpit and carry the loads down lower, but I don't know any details. As far as getting a partial drawing set, I guess contact the Hatz association and explain what you need.

Regarding the spring gear... the standard gear attaches at two points, transferring the loads to the strong points at the forward flying wire attach point and the lower front wing spar attach point. WIth a narrow spring gear, you would have to design a supplemental structure to dump the loads in the same places. There have been quite a few biplanes with lower fuselage failure due to an inadequately engineered spring gear conversion. Not saying you can't do it, but you have to do it carefully.

Thanks Dana, still in the thought process on what I will do.Rick

If you have a look at Rick Hansen's Travel Air in the April 2021 Sport Aviation magazine, the door on the passenger cockpit has a curved bottom.

I run the idea by a couple of engineers I see at coffee every week. The consensus was I could remove that part of the longeron and add a curved piece to lower it a bit only if I added a brace across where the original piece was !?!

Joking aside their advise was the same as Dana's. That I should do the analysis before messing with the structure. The door does look real cool with a curved bottom and probably helps with access.

Thanks Murray, I located a CB-1 with the longeron lowered for a door that I am going to look at, and I know the guy flies it a lot, and he loves it. So I will let you know what I see. PS, I have been through Saskatoon on my way to Edmonton a couple of times a few years back. I like your part of the world. PSS. Have you seen the TV show "Corner gas" my wife and I really like it,( at least I do anyway). I think it was filmed in Moose Jaw, which is also a cool town. Thanks Rick

Just a test, checking on the forum post, it has not been letting me in as registered member

Rick - Corner Gas was my favorite. I was though Rouleau (Dog River) and couple times while they were filming.

I'd really be interested in the modifications for lowering the longeron for the passenger cockpit. Can you post some pictures when you get a chance to have a look at the CB-1 that has been modified.

And next time you're through Saskatoon stop in. I'll send you a PM with my number.