Warbird Information Exchange

Hello Folks:

I am looking to have some difficult stringers made, and asking if anyone knows of any sheetmetal shops which are capable of doing aerospace quality work at a reasonable price?

Thanks!

For the Hawker Stuff you could try Sanders Aeronautical as they have a great deal of sheet metal experience with the British Hawker stuff.

_________________
Rich Palmer

Remember an Injured Youth
benstear.org
#64- Stay Strong and Keep the Faith

BOOM BOOM, ROUND ROUND, PROPELLER GO

Don't Be A Dilbert!

Make sure what you are looking at is a formed piece and not an extrusion too. Vultee used what looks to be formed shapes in numerous locations, but when you look at the drawings, you find they are extrusions instead. Look very carefully at the cross section and you can tell.

Do they need to be roll formed or can they be brake formed?

Hello Brandon:

Most likely roll formed because of large bend radius. From .125-.343"

Thanks,

Chris

They typically can be made on a press brake depending on the shape. The main reason for roll forming is mass production.
Almost had to make some J stringer for the SNJ but Raytheon used the same shape in King Air wings.
Military repair manual for the King Air states the same part is acceptable if made on a press brake, hand brake or roll formed if made from the same alloy and thickness as the orig or whatever spec stated.
If joggles are required then it would probable need to be done 0 or soft and Heat Treated after joggling.
Roll Forming Corp made the King Air material and I believe has a 20,000 foot minimum per a conversation with Bill Yoak.

_________________
Rich Palmer

Remember an Injured Youth
benstear.org
#64- Stay Strong and Keep the Faith

BOOM BOOM, ROUND ROUND, PROPELLER GO

Don't Be A Dilbert!

The Vans RV kit series airplanes uses the same section J stringer (same thickness) as is used
all over the T-6/SNJ/Harvard. Main difference is it has the main J section, but not the tiny
lip on the riveted side / edge (that's easily put on there with a brake and trim process).

It's relatively cheap too (about $1 dollar per foot, last time I bought 10 eight foot sticks of it).

Bela P. Havasreti

The horizontal has stringers different than the rest of the A/C for thickness. .025 for the J and .020 for the L.
I believe the wing J is .040 or at least the S123 is but it is the same shape as the horizontal section but .015 thicker.
And this lacks any kink on the skin leg.

_________________
Rich Palmer

Remember an Injured Youth
benstear.org
#64- Stay Strong and Keep the Faith

BOOM BOOM, ROUND ROUND, PROPELLER GO

Don't Be A Dilbert!

Some shapes can't be easily brake formed, radii too close together for instance. It would help to see the cross section.

In any case I wouldn't know where to get it made. Maybe WestPac could do it?

Thanks Rich. I haven't torn into my wing panels yet, but I re-skinned the entire aft fuselage / tail cone
section as well as both horizontal stabs and the vertical fin. The tail cone has the same stringers as
the empennage (same basic shape). The spot welded stringers in the tailfeathers don't have that
little lip, but the flat / skin-side section of the stringers you get from Vans is actually wider than those
NAA spot welded stringers so you can trim them to size and/or form the little lip on the stringer and use
them in the tailcone (there are a good number of brand new RV J section stringers in my SNJ tailcone,
and also in the tailfeathers of my SNJ!).

Bela P. Havasreti

I got quotes from Alcoa and a few top sheet metal shops around the country. So far Alcoa is about less than half the price of the competition. Alcoa will do the parts as an extrusion where the others will do it as roll forming from T0. What I am trying to find out now are the mechanical properties of a roll formed part vs. an extrusion.

The extrusion has a longitudinal grain direction, while roll formed is lateral. The roll formed version is rolled out of very soft material making me draw the conclusion that work hardening is similar to the work hardening an extrusion experiences.

The drawback might be that the extrusion may have more impurities in it.

When I was rebuilding the Harvard, I did notice that the extrusions were more prone to exfoliation corrosion later on.

My conclusion is if the final product of both are 2024 T-3, both experience similar cold working, and the extrusion has a longitudinal grain direction at the same time the extrusion might have some impurities.

I do know that the yield strength of 2024T-3 is the same across the board whether extrusion or rolled die pressed.

Anyone have any engineering data on this? I haven't been able to find any engineering papers or tables on one vs. the other.

WIXer "Sabremech" aka David S., Warbird Heritage Foundation maintenance director and his business partner can make anything and are have FAA Parts Manufacturing Approval" (PMA) capability. If I need anything fabricated for my T-33, I go to these guys:

http://www.vintageairworks.com/

No email on their website, I guess they like the word of mouth, walk in approach..

There's a company in Australia called "Aircraft Raw Material Supply" which regularly advertises in Classic Wings magazine that does custom extrusions in short run, short turnaround times for aircraft projects. I have no idea what their reputation is, but have always wondered what their prices would be in comparison to the major facilities. No website was listed, but the contact is a guy called Malcolm - e-mail: mlt@bigpond.net.au and phone +61 0408 200 795. I'd be curious to know the results if you do contact them.

Cheers,
Richard

_________________
Richard Mallory Allnutt - Photography - http://www.rmallnutt.com

It's on the bottom of the text on the homepage.

_________________
Defending Stearmans on WIX since Jeff started badmouthing them back in 2005.