Silicone hinges

[schrederman]

Guys,

I am doing a coupe of builds and I've heard of silicone hinges, but never have I seen them. Could someone please do a pictorial/explanation about them? Or... if they're no bueno por nada... Let me know why... PLEASE... with sugar on it... :D

Starting on my flatter-winged Hawk with ailerons and looking for better ways to do stuff... and El Jefe is in the works, too...

Jack

[sekollera]

Jack,

See here:

http://pagesperso-orange.fr/aeromod.concept/english_build_Voltij.htm

I've done about five Aeromod planes this way. Works quite well. Use real silicone, wait two days before removing the tape or working the hinge. Others use harder 3M 5200 or Goop, but I like the pure fishtank silicone.

/Adam

[glderguy]

Never ever use blue painters masking tape when doing silicone hinges. Ive done several planes using the system Adam posted and it works great. Dont make hinge too thick as hinges become very stiff. Reason you dont want to use blue masking tape as something in the adhesive will not let the silicone cure properly if at all.
Walter

[schrederman]

That looks too easy... Thanks... Will it work on built up stuff?

[gklimber]

Hi,

Go here:

http://genie.rchomepage.com/

and look in file 9 under (of all things) "Silicone hinging". There are pictures and all.

Cheers,
jer

[nuevo]

try here.... http://www.google.com/search?q=silicone+hinge

seriously, this one should help.
http://www.rc-soar.com/tech/silicone.htm

I've done it several times. The key is getting the thickness of the silicone bead very consistent. I use a popsicle stick sanded to a point, and then the point rounded to provide the exact radius I want. That radius determined by experimentation. I use that stick to scrape off any extra silicone, then let it cure. Works every time.

Oh, you can't do bare foam surfaces. Face the inner surfaces with FG first.

[seanpcola]

I've done around eight sailplanes with silicone hinges and love em. Everything stated above is correct especially the part about consistency in thickness. I found that the cheaper the masking tape the better it works. Stay away from the "Painter's tape" as glderguy stated. I experimented with many different brands/types of silicone and IMO the aquarium silicone types seem to work best. Clear and the most flexibility. I was surprised at how well this works on flaps with 90+ degrees of travel.

Sean

[Jurgen]

It's in german, but it has very nice color pictures of silicon hinging making.
Cheers ;)

[lincoln]

Can you use Goop? I hate silicone. Ok, ok, I DISLIKE silicone. Nothing sticks to it. (and that's an exaggeration, but not much of one)

The Ava has spoiler hinges that look like silicone hinges. I don't know if they are, or if it's some other kind of goo.

[seanpcola]

Can you use Goop? I hate silicone. Ok, ok, I DISLIKE silicone. Nothing sticks to it. (and that's an exaggeration, but not much of one)

The Ava has spoiler hinges that look like silicone hinges. I don't know if they are, or if it's some other kind of goo.


Goop is way too stiff. Also stay away from any of the household silicone products such as the colored types. What you are looking for is the "pure" silicone products such as the aquarium sealer I mentioned earlier. Good rule of thumb is the worse it smells the better it works in this app. :eek: :D

With the correct silicone and prep (read clean) you should have no problem with the hinges staying adhered.

[Andy W]

Goop breaks down quickly with exposure to sunlight.
..a

[jtlsf5]

Good rule of thumb is the worse it smells the better it works in this app. :eek: :D

With the correct silicone and prep (read clean) you should have no problem with the hinges staying adhered.

And that stinky smell is acetic acid. Think vinegar (3% acetic acid) with all the water removed. That is what is released when the better silicones cure. Not what you want to do in a small, closed area. Not toxic, but irritating.

JT (the chemist)

[rdwoebke]

Hey Jack,

I did silicon hinges (at least I think it was silicon) on the rudder on my Psyko #1. Now I'm about to do rudder on Psyko #2 and will do it the same way. I am very pleased with the results on the rudder. BTW, I think I used the blue painters tape! :) This time, I'll be sure not to though (although I did not have any adverse affects).

Ryan

[Robglover]

When you get the stinky silicone for hinging remember to hide it when you are doing electrical work. The stinky stuff is great for this application but it will cause corrosion of electrical and electronics components. You need the non stinky kind for your electrical uses.

And these hinges work great.

[slopemeno]

If you don't want to use Goop, try E-6000. It's made by the same guys, and you can get it in colors, and with a UV inhibitor as well. 3M5200 works well also.

[bobby legue]

I tried a mock up of a silicone hinge in this fashion. I marked the psuedo sub rib and the flap with a line parralel line to where I thought the silicone should end up. After fiddling with the amount of deflection to match my "high tech" silicone applicator so the ends of the stick would end up at both lines, I used the popsicle stick to smear the silicone into the space and firmly up to the tape on the other side. I let it cure and removed the tape. It stayed in the deflected position as expected. The hinge had a little resistance but did not bind.
The result was a working hinge but the attempt failed as the radius given by the stick pushed the flap piece back about one eigth of an inch when pushed into the nuetral position. However the results shows potential and with some more minor adjustments Im sure it can be worked out.
My next attemp will have a piece of folded waxed paper inserted into the silicone at full up deflection as Im doing this for a bottom hinged flap.
This is fun!
Bob

[Andy W]

Based on this thread, I attempted these on my High Aspect I am putting together. I did just one aileron as a test first, it worked very well, with just a small bead of silicone the hinge was very firmly attached, but moved quite freely.

I had an issue, however, with vertical alignment. When I removed the tape, the aileron had "sunk" about 0.5mm, so there was a tiny 'step' down from the trailing edge to the aileron. I could have lived with it, but as this was a test, I pulled the hinge apart and will do it again. I had allowed this to cure while sitting at a slight angle, about 30 degrees 'up aileron', to prevent the silicone bonding the facing surfaces together, and I'm sure that's what caused it. I will do the next one with the wing in the foam bed, so everything will be aligned. I'll just have to be really careful not to get too much silicone on the face of the surfaces..
..a

[seanpcola]

Andy,

What I do to prevent the two issues above is to first, mask off the faces with tape, leaving of course the top (bottom if doing flaps) 1/16" or so exposed. After applying the silicone and dressing it with a stir stick shaped to the correct radius I then peel off these two pieces of tape. Last step I do is clamp the surface to the wing using something like paint stir sticks, top and bottom, spanwise and bridging the wing and the control surface. You really only need to do three areas, both ends and the middle.

What surprised me the first time I used this was how well the flaps came out. Absolutely no problems with 90 degree travel. :)

[Andy W]

Thx. That would do it. Tape is cheap!
..a

[Neil Stainton]

The Ava has spoiler hinges that look like silicone hinges. I don't know if they are, or if it's some other kind of goo.

I believe they are hinged with silicone.

Neil.

[Andy W]

Hmm.. pretty sure mine is just taped.. have to check that out.
..a

[seanpcola]

Mine are taped also.

[Neil Stainton]

That's what Vladimir told me.

[bobthenuke]

My Super Ava has the spoiler hinged with silicone.

-bob

[davidjensen]

Success! Last night I taped up and gobbed the 100% aquarium grade silicone into the hinge area of the v-tail surfaces on my Erwin. I spent about 10 minutes each side dabbing and rubbing the silicone into the flat surfaces of the skin. Then I wiped it with a wood stick tool. This evening I removed the tape and the hinge is GOOD. It is very flexible and provides more than enough throw. SO I added and additional layer of silicon this evening and retaped and clamped it for another 24 hours. My hope is that it will stiffen the hinge and make it more secure. Pictures tomorrow.

[Andy W]

I found a method that worked for me to. The key to success was to increase the gap between the hinged portion of the surface. This results in an overall larger hinge cross section, which is far easier to create. It also flexes better, instead of bonding the two surfaces together as a strip. I originally had <.5mm between the top skins (aileron), a gap of ~1mm and increasing the taper on the surface LE makes a huge difference..
..a

[seanpcola]

Guess I should have mentioned that :o . You don't want a real close tolerance like you would with other hingeing methods. There has to be a little "meat" to the hinge. I typically go with roughly a little more than 1/16".

[davidjensen]

The additional layer of silicone worked great. It stiffened up the hing nicely. The gap is about 1/16 for these small surfaces. This weekend I will do the flaps and ailerons. The gap on the flaps is going to be closer to 3/32" to get the trailing edge to line up right.

[KevinSharbonda]

Pictures guys?
Thanks in advance!

[davidjensen]

OK since you asked. This is a different type of silicone hinge from what I'm used to. You can see the gap and I used 5 times more silicone than the other type with faced edges. I used a wood stick to smooth and form the silicone and I may have to add an additional layer as I did with the v-tail.

[tonyestep]

This thread is really informative! I have never made a silicone hinge but now I probably will. Thanks, guys.

[Andy W]

For my flaps, I am thinking of routing out a "step" along the lower skin hinge area, and filling it with silicone. I want the "top" of the step to not be adhered, however. This will give me a rectangular strip of silicone on a surface that may be required to deflect a great deal under significant load.
Wondering what I could use to prevent it sticking? Just had a thought - packing tape along the step would probably work well, the shiny side will pull off the silicone easily..
..a

[seanpcola]

A Mylar strip might do it. Wax? Several choices. Good idea and worth an experiment. On the ones I have done there have been no issues with flaps going 90 degrees or even a bit more. Having said that there is always room for a better mousetrap. ;)