Botton hinging flaps ?
 

What is the best way to bottom hinge flaps using Robart hingeponts ? It is very difficult to drill the hole right at the bottom edge of the wing T/E at the correct angle for a Robart hingepoint. After some experimenting I find that most times I ended up having the flap too low or too high even tho I used a jig with an angle hole that sits nicely on the T/E . I am thinking of switching to C/A hinges but I am sure its not easy to make a slot right at the edge as well plus the c/a hinge tends to be stiff and the servo has to overcome additional force to maintain the flap in up position. Any suggestions? BTW its a foam core wing for EDF airplane . Tks

RE: Botton hinging flaps ?
 

I would suggest using a Klett or Dubro nylon hinge. You can put the slots in at a slight upward angle in to the wing and the flap. If there is some slight variation in the angle from hinge to hinge it will have no effect as long as the hinge center line is constant. I did this on my last B-25 and it worked out fine.

RE: Botton hinging flaps ?
 

I have drilled the hole at an angle with no problem.As long as the hing center lines all line up it will work great.

David

RE: Botton hinging flaps ?
 

The hinge centerline will have to be exactly on the bottom edge of the wing T/E which is very difficult to accomplish . I will try to use klett or dubro this time around. Using the GP hinge slotter will be a real challenge ! I used Robart hinges the last time and it was not to my satisfaction even with a jig.

RE: Botton hinging flaps ?
 

You will have more control/accuracy by CAREFULLY using a #11 blade to make the slots instead of the slot machine. It is a lot slower, however, in this instance, accuracy is more important than speed.

RE: Botton hinging flaps ?
 

I use the plastic hinges that have a removeable pin.
Pull the pins out of the hinges and run a LONG piece of stiff pushrod wire thru all the hinges on 1 surface. Take a straightedge long enough to make a line the length of the surface. Put the pencil down and start pushing slots along the straight edge in the locations. Make the slots way to wide for EASY slide ins later. DO NOT WORRY if the slot is angled up or down a lot. The hinge will automatically take care of it. ************DO NOT TWIST the slot cuts.************* That WILL BIND any hinge. This is where a WIDE Exacto blade helps keep all the slots from twisting.

I use a metal straight edge and using enough foam rubber around the control surface, put it into a vice or clamp it between 2 pieces of wood to steady it while working. Nothing is able to move except the straight edge and Exacto blade.

I sometimes use clear tape to hold the straight edge steady and just poke the blade up and down.

Easier to do than write.

The long wire holds all the 1/2 hinges in perfect alingment while the 30 minute Epoxy sets up. I stuff a TINY bit of glue into all the slots first. WHY. As the REAL hinge 1/2's are pushed in, NO GLUE can slide towards the exposed hinge pin holes.

You DID PRE VASALINE the hinge joint edge of the hinges ????

Repeat the mating 1/2 surface the same way.

It really is foolproof.

RE: Botton hinging flaps ?
 

I think I will clamp a straight edge to the bottom edge of the wing T/E where the flap is located and use it as a guide to manually cut slots for the hinge using # 11 knife.

Tks for all the suggestions.