Nose wheel Cubbies

[atom]

This is just the follow up as to the accident of my cubby ZU -DWY at Baps earlier this year.
I am now in the process of making sure that the nose wheel is made more sturdier than the existing one. On close inspection i noticed that the wall thickness of the nose wheel tube differed at the place where it broke off with comparison to the rest of the tube.
I am in the process of ensuring that ONE tube is used for the nose wheel and the tube wall thickness is in the range of 4-5mm.There will be no welding done on the tube as it weakens the metal. I will have the product completed in 2 or 3 weeks. It will be advisable for all the cubbies with nose wheel configuration to do that mod. As yet CAA has not visited me for any further investigation as to the cause of the nose wheel failure but if you look at the material used there is no doubt as to the weakness of the structure.
Will keep you informed..

Atom

[grostek]

Hi Atom,

The Primary strength from a tube comes from having sufficient diameter.

So if the original tube that failed had a diameter of 50mm x 2.1 wall thickness consider using a diameter of 63mm x 2.1 wall thickness.

This will give you an approx 26% additional material.
It will be be able to take approx 21% more load.
It will also have approx 26% more Buckling Strength
Finally it will weigh approx 26% more.

So if the original nosewheel strut weighed for example 4Kg then the replacement would weigh 5Kg.
Going the 4mm or 5mm route will very quickly double the weight of the new part and for very little gain in Buckling strength.

Then also consider making the bend gusset over the curve portion of the tubing longer so that more of the curve is covered by the gusset.

During welding of tubing it is important to have gaps more or less equal to the material thickness , this is to ensure that the finished weld has full penetration.

Hope this helps you.

Kind regards,

Gunter Rostek.

[atom]

Thanks for the info Grostek.
the diameter of the strut is a fixed 35 mm so i cannot change that unless i do mods to the engine bracket. Increase in the wall thickness should be definately better then the existing pipe they fitted on without doing too many changes.

Thanks again
Atom

[grostek]

Hi Atom,

Sounds like you dont have too many options.

Hope you have her back in the air real soon.

Kind regards,

Gunter Rostek.