Stearman PT-17

[Brenton]

Hi, I am building a Stearman PT-17, I'm not sure where L-3, L-4 and L-5 go. Any help is greatly appreciated. Thanks

[davidchoate]

Look on Plan Sheet At step 1. BUILDING FUSELAGE FRAME- The "l" parts are toward the rear appenage . look at the 3d drawing lowest on that page. L5 is the rubber motor peg support, L3 and L4 are structural webbing it appears for the tailwheel and horiz. stab.Wish I could show You, but My soldering iron got a bit close to My phone and the camera is a little blurred. But the plans are clear.

[davidchoate]

"L" parts represent "longitudinal frame" parts I think.I kinda think I wet L-3 as it follows the between the top 2 stringers the stab would rest on, and proceed on a slight curve the length of the stab center, and needs a curve. If stringers are not on 1st they will not go on. They are about last.

[David Lewis]

The letter prefix I believe indicates the building sequence. You start with A parts, then the B parts, etc.

[backyardbalsapilot]

I never realized that. It makes a strange amount of sense, though.

[davidchoate]

David Lewis; if Youy see this I think Maybe you may move this to sTABILITY THREAD, BUT i AM EXPERIMENTING WITH bIPLANES, AND WONDERED IF THE TOP AND BOTTOM WING OFFSET WAS FOR STRUCTURAL STRENGTH, OR STABILITY?

[dirk gently]

If you mean stagger, than it affected structural rigidity in a negative way, but it improves the wing lift, as the wings are not in each other's way, to put it in layman's terms.

[David Lewis]

Positive stagger moves the high pressure area below the top wing away from the low pressure area above the bottom wing.

The Beech Staggerwing was probably arranged to make a convenient place to mount the main gear.

[Chris A.]

I can understand positive stagger, but how does negative standard work? For instance the Beechcraft Stagger Wing.

[dirk gently]

In the same way. The stagger is negative, so that the top wing does not obscure the view. But what David said above still applies.