Cozy Mark IV Retracts Main Gear

[Vacabrava]

Hi all,

How I built my own retracts main gear profile, and it is specific made to the Cozy Mark IV, I decided to open a thread about him.

I think with some mods we can do one LEz fit too.

I saw the other threads, seeking for information about the landing loads involved.

What I found were opinions of our experts on the configurations and performance between Velocity style, Drybread and Berkut style.

I wish that you fellows guided me on the gear tests.

I need some guidance with respect to weight / strength of compression that each leg must bear with the safety factor.

What kind of impact test could I perform, some suggestions about that too.

I will not hire an engineer to do calculations. Since I am building an experimental plane, I will try my project in my own Cozy.

I'm doing this for the benefit of the community, and to my CZ coolness.

But I open this topic to discuss the tests that I must perform, the calculations that I must to do, and whatever you want to talk about the specific profile that I developed.

It has much information on my web site at ch 09, and videos too.

Feel free to make your comments and give me tips.

The leg looks good, it was well compact, I had some gaps in the extension of central pivot but was filled with flox and epoxy. And it's clearly overbuilt.

I will destroy that one performing the tests. And I will try to make one with just 13lbs.

Look, in that one I don't used vacuum nor the external caul plate, with these two process I can reduce pennies in the weigth.

The best thing on this, is that I will build everything with a minimal cost.

Hugs to everyone.

[TMann]

My only concern with your design is how well it will shand up to a drop test (which you will need to determine the gross weight limit,)

Where are those stresses focused?

 

Waiter has a good segment on his web site. It is based on the Infinity gear he has installed on his plane. If you are concerned that your gear would not stand up to this then don't fly it.

[Marc Zeitlin]

I wish that you fellows guided me on the gear tests.

I need some guidance with respect to weight / strength of compression that each leg must bear with the safety factor.

What kind of impact test could I perform, some suggestions about that too.

Read FAR's 23.721 - 23.735 for landing gear design requirements. Part 23, Appendix "C" might be useful, too.

 

I will not hire an engineer to do calculations. Since I am building an experimental plane, I will try my project in my own Cozy.

I'm doing this for the benefit of the community, and to my CZ coolness...

It is certainly admirable that you want to learn how to design landing gear is a safe effective manner. The FAR's listed above will give you an excellent set of requirements and tests that must be performed and passed to certificate an aircraft under Part 23 (Normal and Utility Category).

 

Good luck.

[Vacabrava]

Thak you Marc,

 

I make some calcs and get that if I apply 1.5 safety factor, to the CZ gross weight, I think mine will be 2160lbs. I have 3240lbs to test each leg.

The drop test, I will do the maximum, 18.7 inches of height. I will continue to ready the FARs.

 

And TMann, I know Infinity gear, very beautiful product, but I don`t like hydraulics, they leak`s.

If I proceed and pass FARs I am ready to fly, with legs fixed on the projected landing gear bulkheads.

 

I let you know when I perform the tests.

 

Best Regards.