Rib material ?

[kauaicuda]

Hello and good morning, I just ordered plans for a bearhawk LSA, cant wait to get this party started!

Could anyone kindly share the material required for the ribs? I'd like to start shopping around for metal. Thanks in advance!

-Robert Hansen
Frederick Maryland

[Frank]

Robert, I’m in a similar position as you. I’ve had the LSA plans for several months but have not been able yet to start building.

Trying to finish multiple house projects, get the shop together and exit the workforce (retire).

I hope to begin in earnest with the LSA about the time snow starts to fly here in Denver.

When you receive your plans you will also receive “The Bearhawk LSA Book”.

It states “We do not supply a materials list”. And then proceeds to give good reasons for this.

My thought is to do what Eric Newton has done:

http://mybearhawk.com/wingneeds.pdf

http://mybearhawk.com

I will go over each page of the plans in close detail (at first the wings) and list every part specified.

And then lay it out in a suitable application (Adobe Illustrator is what I have) and try different scenarios.

I’m thinking I won’t order all the wing materials at once; just what I need for ribs, stiffness, spar attach brackets.

I’m thinking the first order can be shipped by UPS. The next order might need to come by truck.

I will also add a margin for practice, mistakes and to have an extra or two of each part.

So, between the various ways the materials can be ordered and shipped, and given our skills or lack thereof, it’s easy to see why a generic materials list is probably a bad idea.

Probably the best reason to make our own individual materials list is to force us to really study the plans.

I’m not there yet but hope to be soon. I’m pondering tools and methods.

Glad to see another LSA getting started.

Soon I will be playing catch-up with you!

Frank Forney
Denver Colorado

[geraldmorrissey]

Try to order material with a plastic coating. It makes life much easier. I order the material coiled, but its a pain to uncoil, cut what you need and recoil. Ordering coiled saves on shipping vs flat. If your ribs are .025 and .032 order a 4'×8' sheet of each. That will keep you going for a long time. Once you have chopped that up, you will have a better understanding of additional requirements. The shipping is not really that bad. You don't really know what your scrap rate is going to be yet and that has to be added in. Good luck.
Gerry
Patrol #30 tanden with lots of scrap.

[geraldmorrissey]

I buy from Airparts Inc in Kansas City. They sell sheet metal by the foot. And they will ship coiled. I wouldn't spend much time trying to figure out material requireme with computer applications. Spend that time making tooling. Just buy some material and start cutting.
Cheers
Gerry
Patrol #30 tandem

[Frank]

In Tony Bingelis “Sportsplane Construction Techniques”:

“The direction of metal grain is a matter of importance when laying out any part that must be bent. That is, the bend should always be made across the grain, or as close to that orientation as practical.”

So I wonder if there are any other ideas or conclusions about “metal grain” especially as it concerns laying out rib shapes on an aluminum sheet?

[jaredyates]

Bob has clarified in the past that none of his structures are depending on the grain direction, or else he would have specified. Good practice would be to bend across the grain when possible, and categorize ribs as not possible.

[geraldmorrissey]

I located the material grain to be be 90 degrees at the maximum thickness of the airfoil for the center rib of the Patrol. Seemed like a good compromise. You have no flaps so you may want to shift it a little. Others will chime in with options. Nose ribs I went 90 degrees at the most aft of the rib profile. You two guys should share tooling. That is a big part of rib building. Note that the spar webs go completely against the grain rule. Lots of experienced builders on this forum to guve you advice.
Gerry
Patrol #30 tandem

[johnb]

Robert,
Welcome to the LSA plans build club. Most of the ribs are .020. I bought most of my metal from a local TW Metals distribution center. They sell in 4x12 sheets and will add protective plastic. The more you buy, the better the price. If I recall, I used 3 sheets of .020, 1 sheet of .025, and 2 sheets of .032. That got me material for most ribs and spar channels to get started. Other thicknesses that didn't need 4x12 sheets, I ordered from Aircraft Spruce.

Like others said, study the plans, make your rib tooling. Have fun and good luck.

-John

[Chewie]

Bob has clarified in the past that none of his structures are depending on the grain direction, or else he would have specified...

Exactly. Case in point, the wing spar flanges bend with the grain.