Okay, here's a couple of questions about my current re-doo's of some of the older 1/2A profiles.

1)  I've acquired a Brodak Stuntman 23 - my fondly remembered Goldberg Sportsman 18 and Jet 21 not being available - and a Sig Deweybird.  Both of these kits, and others I remember from a distant past, use two halves for the elevator that have to be joined and reinforced.  I'm inclined to dismiss this as some kind of "save wood" die-cutting issue.  I am also inclined to substitute a "do-it-myself" one piece elevator to go along with the one-piece stab.  I'd still put that piece of reinforcement anyway, it would stiffen up the elevator, but I'd get rid of that glue butt-joint between the two halves of the elevator.  Can anyone clue me in to the why's and wherefor's of this 2-piece approach and am I missing something about the structural consequences of the kit approach?

2)  I've read on a couple of posts that some of you guys REALLY prefer the sewn figure-8 hinge to the criss-cross cloth hinge for 1/2A sized models.  Are you at all concerned about not having a tight hinge line to prevent air leakage?  I'm being given guidance that on my larger models I should consider making the criss-cross hinges run the entire distance between the fixed surface and the movable surface.  Since that's consistent with my full-scale gliders, that seems like a good approach; but, at the same time, I understand the desire to have really floppy, no-resistance movable surfaces.  Any guidance here about the distinctions between 1/2A and larger models?

TIA,
Jim Howell
Huntsville, AL

Later edit:  I have just discovered that Brodak has laser-cut a 1-piece elevator, contrary to the duplicated Goldberg "instruction sheet".  I'll still put that reinforcement strip, tho'.  And I suspect that they may have up-sized the thickness from a 1/16" sheet to a 3/32" sheet for the stab/elevator.  Never having built the S-23 years ago, I don't know/remember this issue.

Not sure how important the sealed hingeline is to 1/2As, with slower speed and lighter loadings, but the figure-8 sewn hinges can be made about as tight as you want, and still be very free-moving...that's why they're so popular.

The elevator in the pic is incomplete; more hinges were later installed.  Just included this to show how tight a sewn hingeline can be.

I believe it is critical to have the control surfaces as free as possible on a 1/2A model.  It is MUCH more important than with the larger planes.....

Tim, Ray, Bill,

Thanks for your replies.  I was missing the "low line tension" characteristic for the 1/2A's as the difference between them and the bigger guys.  Floppy elevator is the goal!  That's actually not a problem for me.  My previous practice back in my dark ages on ALL my C/L models and my towline glider rudders was to use the sewn figure-8 hinge.

Thanks,
Jim Howell

With figure 8 higes, I make an appropriate small notch in the elevator so the hinge line can be tight.  I use dental floss for the hinge material. 

If you still want to seal the gap you can use a method Walt sometimes used on his logs. Simply run a cloth (I use nylon) hinge along the bottom of the "empennage". Be sure to taper the LE of the elevator (I sand a wedge), and be careul of how much paint gets in the gap so it stays flexible.

George

Look at John's Snapper at the end of the "fuel consumption" thread for a good example of "zig-zag linen hinges butted together". A perfectly sealed hingeline, for those who care.

I use cloth zigzags on my 1/2 A's I use eight pieces of cloth and have no trouble with free movement. One of my first 1/2A planes used those plastic hinges and wow that thing can be a handfull. My dad built his stuntman by the book and I wish I could give you a report but he hasn't flown it yet arghhhh.