Hatz Biplane Association

New member to the Hatz Association and this is my first post on the forum.

In 1983 my brother started building a Kelly D, plan number 30. After working on it for some time, he hung the fuselage in the ceiling of his shop and stored the wings. I have recently acquired the plane and have been in the process of picking up where he left off. I will be modifying it somewhat -- I have made a down payment on a Rotec R3600 radial engine and will be rounding the fuselage -- can't have a rectangular biplane with a radial engine. Another modification that I am presently working on is redesigning the landing gear for a more conventional look and raising the fuselage to handle an 80 inch prop. Have a couple of questions at this point: 1) Has anyone out there put a radial on a Kelly -- if so would love to bend his ear. 2) I am going to use Spruce shock absorber coil springs on the landing gear -- part number 06-13200. I have a design worked out but know the use of the springs has been done many times before. Does anyone have a "standard design" -- don't necessarily want to recreate the wheel. Maybe there is another spring/system that someone has been using.

Would appreciate any comments, ideas, etc.

Thanks,
Stan

Hi Stan. Welcome aboard!

The Kelly-D does not seem to be as actively built as the Hatz, so as far I know, no one has put a Rotec on a Kelly-D. There are a few in progress out there, but there hasn't been much activity here on the forum.

The spring landing gear, as you said, has been done many times... including here on the Hatz Classic, Bantam and CB-1 so plans from any of them would probably work for you with some modification to fit the Kelly-D.

Hope that helps.

I am nearing completetion of this Kelly D project as stated above. When it was picked back up, the decision was made to mount a Rotec R3600 150HP radial engine and round the fuselage, etc. Doing some preliminary weighing of the components of the plane, it is OK with the 1600 pound gross weight that is listed on the plans but I would like to consider the gross at 1700 -- maybe even 1750. I have the horsepower to handle a little more weight and am installing Bruntons flying wires -- so feel OK there. I have redesigned the landing gear and it's good with the additional weight. Also strengthened the fuselage to handle additional wing loading. The question I have is in reference to the wings and their strength. They are 50 inch chord with the airfoil based on 23012 (modified Taylorcraft) and wing loading is 6.95 pound per square foot based on the 1600 gross weight. The spars are aircraft grade spruce -- the front one is 5 x 3/4 inches and the rear one is 3 1/4 x 3/4 inches is size. There is no information that is on the prints or that I can find on the computer on design strength of the plane (G limits) -- I understand it is not an aerobatic plane. The designer (Dudley Kelly) is no longer with us and I can't find any contact information on the design engineer. Mr. Kelly worked on the design/drawings of the Hatz planes and designed the Kelly D to be a "simplified Hatz". I don't have any information on the Hatz wings physical structure to make any comparison as to what Mr Kelly designed into the Kelly D -- and the Kelly D may be a completely different design/airplane than the Hatz. But the Hatz CB-1 has a wing loading of 8.15 pound per square foot and the Hatz Classic has a wing loading of 9.44 pounds per square foot.

With all that being said, I would appreciate any comments.

Stan

Hi Stan,

See appended report from 2003. Maybe the administrator can make the document available on the Hatz homepage as well.

Juerg

ha622 wrote:Hi Stan,

See appended report from 2003. Maybe the administrator can make the document available on the Hatz homepage as well.

Juerg

Juerg,
I have studied your study in detail and would like to discuss a few things with you. My email is: stanholz2@yahoo.com -- will
you send me your email address.

Thanks, Stan

Finished the Kelly D and it took it's first flight on March 31th. Everything was absolutely perfect -- trim, etc. Flight was 35 minutes. I was going to insert a few pictures of her but can't get that done -- will take input from someone on how to do that.

Congratulations!

To upload pictures. click "Upload attachment" below the message entry screen. Then "browse", find and select the file, wait for it to upload, and when you see the "Place inline" button, click it. It will insert the image code into your message.

Trying again to upload a few pictures of the Kelly D.

Wow! The Rotec looks perfect on the Hatz, that is the first one I have seen on a Kelly D. Great job, really nice lines and beautiful paint. I love the way the fuselage fits with the engine, that is always a challenge and yours looks great.

Beautiful!