Tension Hinges also called Laced Hinges or Monokote Hinges

2004.01.08
2004.04.26 - updated: tipos de fita
2005.09.02 - updated: foto de exemplo de aplicacao
2006.04.11 - updated: English translation, reference to "laced hinges" name, link to xtc's RCGroups post

Tension hinges é uma maneira muito eficiente de fazer uma dobradiça com fita adesiva para leme, profundor, flap, ailerons, etc. Tem gente que usa materiais como Monokote mas eu prefiro fita adesiva. Voce pega dois pedacos de fita e cola a pontinha de um na pontinha do outro, parte adesiva com parte adesiva. O resultado e' uma fita que da metade pra ca' tem cola de um lado e da metade pra la' tem cola do outro lado, e bem no meio nao tem cola (e' a parte que colou um pedaco de fita no outro). Essa fita voce cola uma metade na parte fixa (estabilizador ou asa), passa a parte sem cola bem pelo vão entre a parte fixa e a parte movel (leme ou profundor ou aileron), e cola a parte de la' na parte movel, mas pelo outro lado (pois voce passou a fita pelo vão). Dai' cola outra fita ao contrario logo em baixo... ao contrario quer dizer: começa colando do lado oposto da parte fixa, passa pela vao e cola na parte movel pelo lado de ca'. Sempre que for colar a segunda metade da fita, ponha as partes fixa e movel bem apertadinhas uma contra a outra e cole a fita bem esticada. Cole um par desses em cada ponta e se o espaco for grande (um aileron, por exemplo), cole mais um par a cada 10cm +/-. Planeje o espacamento com antecedencia e vá colando em sequencia pois daí voce pode enfiar a fita pela ponta do vao e correr ela ate' a posicao, fica muito mais facil do que ter que enfiar uma fita com cola por um vao apertadinho... (essa parte ficou mal explicada, mas se voce se deparar com o problema vai entender o que eu quis dizer). Para meus aviões de até 2m de envergadura eu uso fita adesiva comum ("durex") e funciona perfeitamente. Nesse tipo de dobradiça a cola da fita nunca é exigida na direção perpendicular à superficia colada, sempre paralelamente (cisalhamento) e nesse sentido a cola resiste muito mais. Para o desprovavel risco da fita se romper, use varios conjuntos de fita, tantos quanto achar necessario. Para lemes de park-flyers por exemplo, em que a dobradiça tem apenas uns 15cm de aresta, eu uso uma sequencia continua de pares desses, sem intervalo... com fita de 1.5cm umas 8 fitas já preenchem todo o espaço e são muito mais resistentes do que qualquer esforço que será feito ali... Em aviões muito maiores use fitas mais resistentes como por exemplo fita filamentosa da 3M (em São Paulo pode ser encontrada na Vick). Eu nao teria restrições em usar uma dobradiça dessas feita com fita filamentosa em um avião 1/3 de escala com 4m ou mais de asa. Faca uma experiencia... funciona bem pacas! Desse jeito inclusive voce nao precisa chanfrar a parte movel para ela encontrar com a parte fixa por uma aresta... pode colar topo com topo que a dobradica funciona direitinho e sem folga.

Tension hinges is a very efficient kind of hinge made using standard adhesive tape. Some people use covering like Monokote (thus the name Monokote hinge) but I like adhesive tape better. Get two pieces of adhesive tape and stick the very end of one piece to the end of the other, sticking the adhesive side of one piece to the adhesive side of the other. After that what you get is a tape that on one half has the adhesive on one side, on the other half has the adhesive on the other side, and right in the middle there's no adhesive (it's the overlap between the two original pieces of tape). Stick one half of this tape to one of the parts to be hinged (A) stab or wing usually, let the middle part with no adhesive in between the two hinged parts (B) and stick the other half of the tape to the other part to be hinged (C) rudder, elevator or aileron usually noticing that one half of the tape is sticked to one side of the stab and the other half to the opposite side of the rudder. Then make another piece of tape just like the first one and stick it right next to it but remembering that the half that goes on the stab will be on the opposite side as the first tape, same thing on the rudder: tape sticked to the opposite side of the first one. Between steps B and C (above) hold the two parts to be hinged firmly touching one another right on the zero degrees deflection position, so not to develop slop. Use a pair of opposite tapes on each end of the hinge and if the hinge is long (an aileron for instance), use another pair every 10cm=4" or so. Plan the spacing beforehand and stick each tape in the sequence they lay on the hinge because this way you can pass the non-adhesive middle part of the tape between the two parts on one end and slide it all the way to the correct position, this is much easier than trying to pass one of the adhesive halfs of the tape in between the two hinged parts when they are already firmly held together... This is difficult to explain in writing, but if you step into this problem you'll realize what I mean... This kind of hinge is particulary effective because the force that holds the parts together is applied parallel to the surface the tape was sticked to, there's never a force trying to peel the tape off. Relying on the peeling resistance of the adhesive by itself would make it much weaker, but the way the force is applied the tape resists much more. Example: stick a piece of tape on the table, hold one end and pull it parallel to the table, compare the force it resists this ways to the force it resists to peeling the tape off the table... very different isn't it? I use standard office adhesive tape for planes up to 2m wingspan with no issues whatever. If you are weary about it space the pairs of tape more closely together. Right next to the pushrod horn (or to the pull-pull horn, whatever...) make sure you have tape hinges on the full 3-5cm (1-2") to each side of the horn. This will be one of the most stressed parts. In much larger planes (3m span or larger) use a stonger tape like 3M's fiberglass weave tapes. With such a strong tape I would easily trust this hinging system to whatever size model plane you may think of. One last great advantage of this type of hinge is that you don't have to bevel the parts to be hinged. You can hinge them directly after cutting (or build the parts straight with no bevel, if built separetely) with the added benefit that on the zero degrees deflection you'll have absolutely no slot on the surface, i.e., less drag. A great hint for building the several pieces of tape that will be required is to stick a long piece of tape to another the same length sideways (instead of sticking the end of one piece to the end of the other) then cut slices of this tape. You only have to be careful so that the width of the overlap between the two original tapes should be about the width of the parts that touch each other on the parts to be hinged (because you don't want adhesive in this place) and that the part of each original tape that remains uncovered by the other strip is wide enough to get a good tack on the parts. Due to the very favorable way the force is applied 1/2" tape is usually wide enough for most uses on planes of wingspan up to approx 3m.

Very nice pictures by xtc of these hinges but using covering like Monokote instead of adhesive tape on this RCGroups post

Veja um exemplo de aplicação no Tim Maia:
See a sample application used on Tim Maia: