exhaust(ing) problem

Discussion in 'Tips, Tutorials & Tools' started by lunarhighway, Feb 19, 2006.

  1. lunarhighway

    lunarhighway Member

    Hi all
    i'm currently building nobi's great agusta A-109e, a great kit that went together perfecly well even after scaling down to 1/72. Yet since the model doesn't have any problems of it's own i decided to add some and convert it to a belgian army 109BA... this version has two exhausts behind the engin that look very simple, but i found, are nearly impossible to do in paper...

    basicly they're big tubes bend so that one end stands at an almost 90° angle from the other... problem is that they have to be very small on the model, around 1cm long... quite small to use a lot of circular sections... It would be great to be able to simply roll a tube and than bend it somehow...but as far as i can see that's not really possible :(

    i think similar shapes are found on ship models so perhaps someone form that department has any advise?

    any help will be greatly appreciated

    (this page has some pics i'm using as a reference)

    GEEDUBBYA Active Member

    Howdy Lunar,

    Ok, I know this may not be much help, but how about pl;astic tubing like that used on fish aquariums? Heat, bend to shape/angle, cool and cut, then paint black with magic marker.
    Or......I know that flexible soda straws can be used in this manner also.
    There used to be flexible paper straws with a light wax coating on them, maybe you could find some of them at a store near you.
    I am sure others will have helpful tips for your problem.

    Have a good day,

    Greg aka GW
  3. Gil

    Gil Active Member

    Hi Lunarhighway,

    You can make tubes out of tissue paper wrapped around a form. Create a form that accounts for two to three layers of spiral wound tissue paper. Coat the form with beeswax or some other suitable mold release agent before winding the first layer of strip tissue so the result can be easily removed from the form. Soak the wound tissue with PVA (white glue) followed by another layer of tissue. Repeat one last time and let it dry. When dry fill with a little spackle or other sandable filler and sand smooth when dry. Finish by slicing the tissue layup in halves to allow removal from the form. Glue the two halves together, touch any seam shows and paint. The tissue is the stuff that comes with shirts and is fairly fragile so work slowly and with a light touch.

    A second method uses the same materials except the form is made from carved styrofoam. Instead of cutting the finished part in two the foam is simply dissolved away with acetone leaving the part ready for finishing. The acetone can be kept in a jar in which the part is immersed and can be reused over and over again. Nail polish remover will work if acetone isn't readily available. The acetone will get thick with styrene which can be used as dope to harden and make paper easier to sand (saturated styrene paper surfaces can be glued with plastic model cement). Some really complex header shapes can be constructed with this method.

    Good Luck!

  4. lunarhighway

    lunarhighway Member

    thanks for the sugestions!!!

    i've heared some inspiring and encouraging things :) , for a second there i though a was facing a wall...I think there might be some straws laying around somewhere, and that tissue might work as well...
    that styrofoam - aceton technique will probably work well to, but i don't like the idea of having these fumes in my workspace/bedroom...however the idea of a disposable mold is interesting

    i'll give it a shot... i'm trying to make some kind of review of this build so we'll see how it turns out.
  5. Fishcarver

    Fishcarver Active Member

    Can you use something like this?

    You will have to "noodle" a bit with the shape. (It is a ventilator from a small torpedo boat)

    Attached Files:

  6. Darwin

    Darwin Member

    Gil, you sound as if you have built a gumbander or two in your spotted path. Seriously, though, many of the construction/design problems I have seen raised lately though these forums have been extensively covered in the model airplane magazines of the sixties, seventies, and eighties (at which point radio control shake-and-bakes pretty well took over the hobby and thus the magazines as well). Search ebay, thrift shops, etc. for model mags such as Flying Models (before the title was changed to RC Flying Models), Model Airplane News. Inside the pages you will find extensive articles on such things as vacuformers, casting small parts with resin, molding small parts using the tissue-paper-mache approach Gil described, etc. The medium of those magazines may have been balsa and tissue paper, but the techniques used are directly applicable to cardstock.
  7. Darwin

    Darwin Member

    And, talking about elbow macaroni....why not? Seems to me I used uncooked elbow mac on many occasions to represent exhaust stubs on my stick and tissue projects.
  8. NOBI

    NOBI Active Member

    Hi there,

    i saw that A-109Ae and look forward to modified my A-109E too but time is very important :) so i did that exhaust in metaseq and unfold in pepakura...non scale and let's you modify that file yourself. i dont know it is wrong shape or not but i think it is no problem :p


    if you want .PDO or .MQO file to edit yourself please PM me

    Attached Files:

  9. Gil

    Gil Active Member


    Yes, many of the techniques are borrowed directly from stick and tissue style modeling. The tissue layup is actually a relatively recent development. It was actually done as a last resort experiment for the following model. It actually worked much better than I had anticipated. One of the best kind of outcomes. The tissue really compacts with the PVA glue to form a very light though tough layered entity. The following image shows the result...,

  10. lunarhighway

    lunarhighway Member

    thanx for the replies,

    and thanx nobi for that developement...and yes,time is indeed a precious thing right now, most of my modeling is done during the weekend, so it might be a while before i can try all these great hints .... right now i'm thinking of builing the unfold patern nobi made and than cover it with glue soaked tissue, and than sand it to shape... seems like a nice compromise...

Share This Page