Step Tubing

[RVG8tor]

Since Van's is closed today I thought I would ask here;

I need some of the step tubing, ACS calls it "Streamlined" tubing. I need to match the stuff my step is made from (8A).

So does anyone know what size it might be. I need to place the order today for other stuff as I leave the country Sunday and will not have a chance to call Van's before hand.

ACS page with the tube sizes: http://www.aircraftspruce.com/catalo...streamline.php

Thanks

[BillL]

Originally Posted by RVG8tor

Since Van's is closed today I thought I would ask here;

I need some of the step tubing, ACS calls it "Streamlined" tubing. I need to match the stuff my step is made from (8A).

So does anyone know what size it might be. I need to place the order today for other stuff as I leave the country Sunday and will not have a chance to call Van's before hand.

ACS page with the tube sizes: http://www.aircraftspruce.com/catalo...streamline.php

Thanks

With all the A's flying out there that one helpful owner or builder, would walk to their RV Factory and measure one for you. I asked a year ago and could not get it either. I don't need a step so terminated the pursuit.

[wirejock]

Originally Posted by BillL

With all the A's flying out there that one helpful owner or builder, would walk to their RV Factory and measure one for you. I asked a year ago and could not get it either. I don't need a step so terminated the pursuit.

Mine are handy
Looks like this is a match.
1.6850.714.0491-1/43/40.62903-11600$13.60

[BillL]

Originally Posted by wirejock

Mine are handy
Looks like this is a match.
Major:1.6850"
Minor: .714"
Wall thickness .049"
1-1/43/40.62903-

Part number: 11600

Price: $13.60

Thanks !!!

OK - I did a few calculations - and this section can handle 100 Ft-lb of bending moment at yield of 63.1 ksi. If someone could now tell us the length of the step and its offset distance from the fuse, then we will have a theoretical step weight capability.
Thanks.

[RVG8tor]

Thank you guys for running down the numbers. I will measure my step when I get back, if someone can run the numbers it would be fun to know what the mathematical limit is on the step as far as weight.

I can tell you I babied my step but i do weigh 260 and mine cracked in the first 100 hours.

Cheers

[David Paule]

An ordinary stress analysis will not show the actual strength of the step assembly, because the failures I've seen photographed and posted on VAF seem to indicate that the cracking is caused by local deflections in the tube wall.

The tube wall is fixed at the weld, while the overall tube permits deflection. I think - not verified by analysis, just a hypothesis, nothing more - that this causes high local stresses in the wall, leading to early fatigue failure.

Dave

[BillL]

Originally Posted by RVG8tor

Thank you guys for running down the numbers. I will measure my step when I get back, if someone can run the numbers it would be fun to know what the mathematical limit is on the step as far as weight.

I can tell you I babied my step but i do weigh 260 and mine cracked in the first 100 hours.

Cheers

FWIW Here are the pictures I took of the Vans step reinforcement.

[Av8torTom]

Others have suggested that vibration and prop wash are major culprits since it is the right side step that seems to crack most often (despite the fact that the left step usually gets more use). Some builders - including myself - have added some shot to the inside of the step to act as a vibration damper. Don't know if it will work, but don't think it will hurt.

http://http://www.vansairforce.com/community/showpost.php?p=954284&postcount=12