Boss248

I am building the Goldberg Ultimate Bipe and I was going to use the "live" hinges that came with the kit. I have never used this type hinge in all my 30 years of building, I almost always use Klett of GP flat hinges but I was doing a pull test and to my surprise the hinge came out of the rudder trailing edge. I did clean the hinge with acetone to remove any mold release and scored the flats of the hinge with 60 grit sandpaper so the only thing I can think of is I did not get enough epoxy in the hinge slot. I have used the live paper/plastic hinges before but the range of movement was a lot less than I needed and the control surface was really hard to push on at it's max through. I have a bunch of Robart medium size pin type hinges but the hinge barbs sticks beyond the wood to a point where the barbs are no longer touching the wood.
I am open to any new or old ideas so let me know what type of hinging you have used in the past.

rayb

My Feedback: (13)

I am presently building a CG Ultimate also. I have not installed any hinges yet but I glued some balsa scraps to the rudder leading edge, the fin trailing edge, elevator leading edge and horizontal stabilizer trailing edge so that the hinges would have something to glue to. I plan on using Robarts also.
Ray

rayb

My Feedback: (13)

By the way Boss248, do you have a copy of Higley's book "Bipes"? Lots of great tips in it on construction of the CG Ultimate. Well worth the money IMHO.
Ray

iowanspctr

Just finishing up a Goldberg Anniversary Cub, looked at the hinges, didn't use them. I'm sure someone has used them successfully but I used Sig CA hinges. I've never had a problem with those and they're really easy to install with the hingeing machine. I think I'll use the Robarts for the Venture 60 I've got in the box, though.

scott7x71

I just put Robart Hinge-Points in a Northstar 40 (duck) and the barbs protruded through the trailing edge stock also. I just put some scrap pieces in there so the entire barb length has something to bite.

The instructions say you only need two barbs to grab but I have never trusted that. I follow the "ounce of prevention...." line of thinking and I've never had a failure.

CafeenMan

As has been said, you should always make sure that hinges are fully enclosed in wood.

In the case of flat hinges, they should always be pinned in place - even if you're sure you glued them in properly. A pinned hinge won't come out without taking the trailing edge with it.

Boss248

I always cover a plane then finish installing and glueing the hinges in so I am a bit confused as to the pinning of the hinges with tooth picks after it is covered, do you cover over the tooth picks with what ever color is to be used??
I did some experimenting with the live hinges that comes in the kit and on some pin/flat hinges I found in a junk box, I installed the hinges in some scrap balsa and used epoxy and both the small pin/flat and the Goldberg pin/live hinges stayed in the wood with me pulling as hard as I could.
The reason I am a bit concerned is the ones that pulled out on my W.M. Extra 1/4 sc.
I am going to be installing a Saito 180 iin the bipe(I know...major overkill) but my buddy had a Y.S 140 in his Goldberg bipe and it was a blast to fly so I says to myself...180 in CG bipe...why not.
Below is a pic of the hinges I have...I am starting to lean towards the medium Robarts. The one main reason I did not just go ahead and use the Robarts is I had already sheeted the hor. stab and vert. stab ...but a small amount of surgery on the under side of the horz. stab and vert stab is all thats needed so I can hen build up the stuff that is already sheeted.

CafeenMan

I normally don't bother covering the hinges on a sport model. What you can do is take some scraps of the covering, put it between two pieces of paper and then hole-punch it. Use the circles to cover the toothpick pins. Oh yeah... I put in the pins after covering.

Boss248

I thought about is a lot and I have decided to do it like I think it Caffenman...which is sinking the hinge in the elevator leading edge and sanding the vert. stab trailing edge with some 60 grit wrapped around a 5/16 dowell rod. This is a more time cosuming task but the way the elevator works with the fulcrum recessed and a radius sanded on the elev. leading edge is like killing 2 birds with one stone. Doing it this way seals the gap because the leading edge of the elev. never comes out of the concave sanded in the horz. trailing edge.

MikeSell

My Feedback: (2)

Have you ever thought of using iron on hinges. Granite state marketed them for years. It is just a two strips of supercoverite sewed together. Each strip spans the gap and the line of thread is the hinge point. They are gapless, limp, and hold on the entire trailing edge. I've used them in models from 1/2a to giant scale without a failure.
When Granite state hinges became hard to find I just made my own.

Boss248

Mike...I do remember the hinge method you speak of...many moons ago in my control line days we made hinges out of silk. This is a cdiss cross type hinge that was actually easy to do. I have also used 2 pices of Monokote...this was done by cutting 3/4" strips of Monokote turning one strip glue up and ironing the other strip glue facing down letting the top piece over lap the glue up piece by 1/4".
Thanks for the heads up on the Granite state hinges Mike...had forgoten about them.

Azcat59

How about trying the Hayes plastic hinges, guys? (Used to be Kraft-Hayes before Phil Kraft retired). Cycle them back and forth to set the plastic, scuff them up, install with slow-dry epoxy (15 min. ok), and you can have near-zero hinge gaps, and hinges that will last for years. I have been using these on all my "serious" airplanes for some 26 years with zero hinge failures. As I understand it, they used to be the "gold standard" when Kraft radios and items were popular.

Clair

CafeenMan

I agree with AzCat. I really prefer Hinge points because they are sooooo easy to install. But Kraft hinges are awesome. I still have a few around.

I don't agree with the "cycle them back and forth a few times" though. For me it was sit in front of a movie and cycle them for quite some time to get them good an flexible. )

Azcat59

An old timer taught me how to "cycle" the Kraft-Hayes hinges.....bend them about 90 degrees each way a few times, then bend them completely back upon the other half hinge.... i.e. bend the hinge back 180 degrees, each direction, several times. I think the package used to say that, in fact. It had something to do with realigning the molecules in the plastic. After this they will be nicely flexible.

Just don't flex them like this when they are real cold....I showed my buddy how to do this one morning at the field, and cracked the hinge....first time ever. Had lots of egg on my face over that one....

Clair

Boss248

Down in this part of the country those type hinges were called live hinges and I have used them on planes that did not need much surface throw. The nice thing about those type hinges is they want to go back to a flat shape which helps the servo but they also have just the opposite effect when the servo is asked to push or pull against the resistance of the live hinge.
I went ahead and did the hidden type hinge using the medium size Robart hinges and moved the fulcrum (pivot plane) 3/16" into the leading edge of the control surface. This meant that a concave was sanded into the trailing edge of the horizontal stab to accept the rounded leading edge of the elevator and now the elevator pivots inside of the concave portion of the horizontal stab which also seals the joint and no sealing of the joint is needed.