Standard FoamBoard Hinge weakness

[Keno]

Just for info if you are looking for straws you will find thousands at a restaurant supply store. In our area it is "Cash and Carry". All sizes are available. Also of course Amazon has them on their site. Only trouble with Amazon is ID/OD sizing is rarely posted.

 

[Piotrsko]

Coffee stirrer straws with appropriate music wire hinge pin full length in the style Lufthouse uses. The foamboard fails before the hinge and they hot glue on.

 

[Kendalf]

So I was at the Yanks Air Museum in Chino, CA and noticed how tiny the hinges are for the elevator and rudder if this biplane (forgot to note what model). It's incredible to me how three tiny bolts can hold each side of the elevator!

 

[Hai-Lee]

Coffee stirrer straws with appropriate music wire hinge pin full length in the style Lufthouse uses. The foamboard fails before the hinge and they hot glue on.

The foamboard failure is the thing that the proposed technique was submitted to prevent/combat. Sure coffee stirrers and music wire will work but they come with a weight penalty which can make some Minis almost impossible to build light and achieve proper balance! Additionally there is nothing more maddening than buying a kit only to find that you need to buy extra parts, (not listed or even mentioned at the time of purchase), just to complete the build!

It is beginning to appear that almost everyone has their own personal preferred method of reinforcing the hinges with a myriad of different approaches and techniques. It was not my intention to start a thread, (Urinating contest), that lists them all but rather to propose a solution that helps remedy the original weakness.

Please try it and evaluate it for yourself! You might find that it performs better than you actually thought possible! Feedback from those who have evaluated it or even used the technique in a flying model, in relation to its performance for them and issues that they discovered would be appreciated and welcomed!

have fun!

 

[Hai-Lee]

So I was at the Yanks Air Museum in Chino, CA and noticed how tiny the hinges are for the elevator and rudder if this biplane (forgot to note what model). It's incredible to me how three tiny bolts can hold each side of the elevator! View attachment 126036 View attachment 126037 View attachment 126038

Nice info but unless the Biplane was made from Foamboard it has little bearing upon the original suggestion.

The tail structure is a rigid frame canvas covered with bolted metal hinges. Because of the structure rigidity there is little hinge support required and 4 were used to reduce warping under aerodynamic load. For the time a simple, effective, and reliable design which was used almost universally in one form or another.

Unfortunately not of use on a FB only plane!

have fun!

 

[kilroy07]

It was not my intention to start a thread, (Urinating contest), that lists them all but rather to propose a solution that helps remedy the original weakness.

Good, then let's not... (have a urinating contest)...

Perhaps if you had started this thread with "How I solve Standard FoamBoard Hinge weakness" it might have better served your purpose.
As it is, I (and apparently many others) took it as an open discussion on solutions for hinges.

The wonderful thing about this community is the willingness of it's members to reach out, to discuss and share knowledge (all in a friendly manner.) I see no one pissing on your idea, but simply other members doing what we do best (sharing and caring.)

I for one am certainly willing to give your idea a try. I am a little concerned about it binding unless significant clearance is made between the different sections (because as you know, those surfaces can/will twist under the forces in flight) but the proof is in the pudding as they say.

I hope you can take a breath and take mine and the other suggestions, not as a threat on the validity of your design, but the communities response to what was apparently an open discussion.

We should all be having fun!

 

[kilroy07]

(forgot to note what model).

Looks to be a Jenny to me.
https://en.wikipedia.org/wiki/Curtiss_JN-4

 

[Hai-Lee]

Good, then let's not... (have a urinating contest)...

Perhaps if you had started this thread with "How I solve Standard FoamBoard Hinge weakness" it might have better served your purpose.
As it is, I (and apparently many others) took it as an open discussion on solutions for hinges.

The wonderful thing about this community is the willingness of it's members to reach out, to discuss and share knowledge (all in a friendly manner.) I see no one pissing on your idea, but simply other members doing what we do best (sharing and caring.)

I for one am certainly willing to give your idea a try. I am a little concerned about it binding unless significant clearance is made between the different sections (because as you know, those surfaces can/will twist under the forces in flight) but the proof is in the pudding as they say.

I hope you can take a breath and take mine and the other suggestions, not as a threat on the validity of your design, but the communities response to what was apparently an open discussion.

We should all be having fun!

I take on your comment as to the naming preference I chose for this thread but then the use of "How I solve Standard FoamBoard Hinge weakness" or similar would be just another post to bring the attention what could be considered as just another personal preference among many! The thread was raised to highlight weakness in Foamboard hinges and to propose an alternative method of doing Foamboard hinges for greater strength and even longevity! Maybe even bring it to the attention of the FT crew themselves for serious consideration!

What attracted my ire, (so to speak), or adverse reaction, was the simple fact that the posted alternatives were NOT Foamboard Hinges but rather hinges from different materials used to replace FB hinges! The technique was proposed so that anyone could buy an FT kit from the store and assemble it in what MIGHT be a more robust manner without needing to add NON-FT materials or to purchase any additional materials.

As for replacement hinges there are a multitude of possibilities, many of which I have used personally in a plethora of different designs from tape to wrapped and soldered Brass tube "T" for use on the tail of a foamboard EIII wing warping attempt. As for the techniques proposed by others in the past and even on this thread I have tried/evaluated them previously for my own personal use but was always seeking a simpler and all FB solution. Heck ! I even tried using tooth picks buried in the foam as the hinge material, (but not practicable really)!

I still look forward to feedback from those who have evaluated the technique for themselves in direct comparison with the standard FT bevel technique.

Have fun!

 

[Merv]

I’ve never had a failure with the tape hinge similar to the suggestion of @Tench745. First do a glue hinge. Put down a small bead of hot glue, then spread, I use a hot covering iron. Then add the tape hinge. To finish, use the covering iron to reactivate the hot glue, binding the tape hinge to the foam.

 

[Keno]

All is good my friends. I have seldom met a fellow flyer that has the same opinion or answer to a question or problem. Hai-Lee thank you for your proposed hinging method. I read many ideas here and I have found they offered me only increased knowledge. This will work there but maybe not there. Learning is a gift and I find nothing in these posts that has not offer me that. Even the goofiest Ideas I have heard/read may either offers me humor or enlightenment. Go for it guys and gals give me all your all your ideas as it provides me with knowledge to solve problems or maybe develop a new model design. This is what it is all about, LEARNING. Sorry for the rant.

 

[buzzbomb]

Thank you for such a great thread, Hai-Lee! You called yourself militant. I'd add hard-headed to that. You are one hard-headed militant son-of-a-gun! And we love your for it! Don't break your wrist on @kilroy07. We can take this to the Bar Somewhere in the Middle of Nowhere, if we have to. I don't think that will be necessary. I'm about to talk you both down by showing you something that I did not come up with, but is totally awesome.

The near total lack of white, exposed foam? The decent bevel? How did I pull that off???....... Ya'll tell me!

 

[Hai-Lee]

@buzzbomb You finally figured it out and then broadcast it to the entire forum. There is not much harder than a head made of bent and riveted steel plates! Hence the avatar!

I don't bust my wrists normally, (I reserve that for special occasions). Sometimes I do get too focused but then it does help when tackling that big problem!

I have vented my spleen on this so I will let other forum users settle this for themselves now! My view has been put clearly! Mind you I will watch and answer questions or discuss any issues that users may have.

As always, Have fun!

 

[buzzbomb]

@buzzbomb You finally figured it out and then broadcast it to the entire forum. There is not much harder than a head made of bent and riveted steel plates! Hence the avatar!

I don't bust my wrists normally, (I reserve that for special occasions). Sometimes I do get too focused but then it does help when tackling that big problem!

I have vented my spleen on this so I will let other forum users settle this for themselves now! My view has been put clearly! Mind you I will watch and answer questions or discuss any issues that users may have.

As always, Have fun!

Perfect! Your head *MIGHT* be harder than mine. I don't have the helmet, but then I don't need it!! If my skull was any thicker you'd have to glue my eyes to the outside.

This is not an off topic post, though. Methods of making a bevel. You haven't commented on the picture.

 

[Hai-Lee]

Perfect! Your head *MIGHT* be harder than mine. I don't have the helmet, but then I don't need it!! If my skull was any thicker you'd have to glue my eyes to the outside.

This is not an off topic post, though. Methods of making a bevel. You haven't commented on the picture.

JUST FOR YOU!

The bevel looks quite well done! Perhaps better than I could achieve using the same methods.

Just be careful with the length of the aileron and its tendency to want to curl and thereby cause the wing.aileron to delaminate at one or both ends in the future.

Nice work!

have fun!

 

[buzzbomb]

JUST FOR YOU!

The bevel looks quite well done! Perhaps better than I could achieve using the same methods.

Just be careful with the length of the aileron and its tendency to want to curl and thereby cause the wing.aileron to delaminate at one or both ends in the future.

Nice work!

have fun!

Did you really think I'd let you get away with that weak-a$$ reply? You still haven't said how it was done, and you are wrong (I hope) about the weakness.

I'm throwing this out not only at you, Hai-Lee, but @kilroy07, @Merv, @Keno. What method did I use to make that to me, awesome bevel? No cutting. No gluing. Just the paper completely protecting the foam, on a wonderful bevel.

I'll give you a hint. I got it from @FDS.

 

[bracesport]

I have used the interwoven tape method for most of my planes - works well, but is a tad ugly - these days I use micro cable ties for the hinges - I like it because it’s mechanical and in my opinion very robust - the PP is a great live hinge, and by folding it in half and wiping the file over the fold (or a hot soldering iron) it creates a nice hinge! Epoxy the cable tie into holes in the FB edges.

 

[Hai-Lee]

Did you really think I'd let you get away with that weak-a$$ reply? You still haven't said how it was done, and you are wrong (I hope) about the weakness.

I'm throwing this out not only at you, Hai-Lee, but @kilroy07, @Merv, @Keno. What method did I use to make that to me, awesome bevel? No cutting. No gluing. Just the paper completely protecting the foam, on a wonderful bevel.

I'll give you a hint. I got it from @FDS.

You obviously did it on the Golf course and you used an iron!

have fun!

 

[buzzbomb]

You obviously did it on the Golf course and you used an iron!

have fun!

Hole in one!

 

[PsyBorg]

I was messing with a project a while back and ended up delaminating a hinge during the build trying to keep a control surface out of my way.

All I did was dry brush a li e of white gorilla wood glue the length of the hinge and re laminate the paper. Layed another bead of hot glue down as normal and wiped it all away.

Why not just pre delaminate a quarter inch of paper at the hinge, tack it back down with the wood glue, then do the standard hot glue reinforcement when that dries.

Super simple no noticible weight gains and super strong. Works with any of the ideas mentioned in this thread.

 

[Hai-Lee]

I was messing with a project a while back and ended up delaminating a hinge during the build trying to keep a control surface out of my way.

All I did was dry brush a li e of white gorilla wood glue the length of the hinge and re laminate the paper. Layed another bead of hot glue down as normal and wiped it all away.

Why not just pre delaminate a quarter inch of paper at the hinge, tack it back down with the wood glue, then do the standard hot glue reinforcement when that dries.

Super simple no noticible weight gains and super strong. Works with any of the ideas mentioned in this thread.

You are correct This problem is one that has been kicking me in the REAR for a very long time. From my own limited experience you can glue the ends of the hinge line but with time it still can distort and separate. When the ends of the hinge line are held firm the centre can start to bow upwards or downwards unless supported or stiffened with a skewer or similar. The larger the span of the control surface the worse it gets and sooner it occurs.

It all comes back to the Hinge point/line and its serious lack of material and support. Short hinge lines are not that much of an issue but when the unsupported hinge line exceeds around 200mm the lack of support allows the control surface to curl or warp and the stresses can separate the paper from the foam in places of high stress over time.

In the past I have added skewers, glue, tape and even music wire trying to lock the control surface shape and position in with limited successes. I shortly will be producing a design for a LARGE control surface design that will offer little or no additional support for the hinge line than that which was described in the first post on this thread. My earlier tests showed a serious instability in shape and alignment using the original technique but this shows such promise the detail design for the project is already underway with the hinge line support as a necessary feature because weight on the projected aircraft is the enemy.

Again I suggest that readers take a few pieces of scrap FB and experiment with the hinge line designs and test their strengths!

have fun!