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Hot C85-12 Baffling Felt Question

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  • Hot C85-12 Baffling Felt Question

    Good Morning Everyone, Another Hot C85-12 question. Does anyone know what the felt like material is that i have seen used as baffling extensions from the back metal baffle to the cowl hood?
    i have airform baffling which are excellent but the rubber has firmed up and i have some very large gaps (curling) maybe some trimming would help?
    I put a light behind the baffle, close up cowling with the hangar lights out.

    Click image for larger version

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    thanks Paul
    Attached Files

  • #2
    Felt is probably not what you need. Difficult to tell from the photos but if the seal material is not formed a little during installation, it will tend to bunch up when the cowling pushes it over. In other words you end up with too much material so you get the wavy effect. May be able to improve this situation by shortening the seal alittle, otherwise the simplest solution is to snip the middle of each wave or take out a this wedge. If they are silicone seals, super glue works if you want to join the material after trimming.

    for the larger openings, add baffle and seal material as needed to close the gaps. Make sure the under cowl pressure is pushing the seals against the cowling so and not blowing them away from their sealing surface.
    Scott
    CF-CLR Blog: http://c-fclr.blogspot.ca/

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    • #3
      every square inch of open area that is not necessary can raise temps by 20 degrees
      N29787
      '41 BC12-65

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      • #4
        oil temp or cht hot?

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        • #5
          Thanks for info,
          oil is hot, i don't have a way to check cht on this plane
          We trimmed the Black rubber type baffling and relief slit the couple remaining ones, Oil temp was 190F at 65F ambient so 125F above ambient.
          Tuesday Before trimming i was reading 200F @ 60F so 140F above ambient. I still have a ways to go but it is clear that the baffling trim lower the Oil Temp 15F or so. i still have light coming thru but very much less, i will try to glue together the tops and report back

          It is a Deluxe short mount 85-12F with starter and luscombe exhaust, cowling sheet metal is marginal. i did install the bottom baffle under the case which seamed to get 5F or so.

          I have always wondered if the cast deluxe grill messes up the airflow enough to be noticeable.

          thanks again

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          • #6
            Originally posted by Ragwing nut View Post
            oil temp or cht hot?
            oil
            N29787
            '41 BC12-65

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            • #7
              Some of the early planes used leather for the baffles. Might try a blast tube on the temp bulb housing to move a little more air behind the diaphragm area..
              EO

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              • #8
                if oil is hot I would look at your lower baffling that feeds air to the oil tank

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                • #9
                  Originally posted by Edwin Otha View Post
                  Some of the early planes used leather for the baffles. Might try a blast tube on the temp bulb housing to move a little more air behind the diaphragm area..
                  EO
                  thats a cessna bandaid and is false sense of security

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                  • #10
                    All the original A-65 engined Taylorcraft I have known have used felt baffle cowl seals...perhaps not the best idea, but maybe original. I have no reason to think that original C-85 engined aircraft would be vastly different, unless these engines were later installed under an STC.

                    Of course, through wear-and-tear (and decades of abuse and neglect and fatigue and oil impregnation and everything else) these felt seals fail. A give-away for original felt baffle sealing is the iron staples used to attach the felt to the aluminium baffles...no-one has the tooling to do that these days.

                    Better to replace with new, or use an alternative baffle seal material, if approved in your country of use.

                    Hope that helps,
                    Rob

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                    • #11
                      Got to agree with Rob. I had felt seals on my 41 and wanted to keep them because they were "original". I put new felt in and even hand bent the staples since as he said, there is no tool to do it any more. Got a bad surprise about 18 month ago when in the pattern I had a soft "pop" sound and the oil temp started to rise, pretty quickly actually. No idea what it was but the temp was closing fast on the red line from early on the down wind to touch down and we shut down on roll out and rolled off the side of the runway. No damage we could find except the felt seal on top had blown back and was tilted AFT instead of forward. It was AMAZING how fast the temps went up with all that air going over the engine and down behind it instead of through the cylinders! I pulled all that nice felt off and replaced it with that awful looking blue silicon cowl seal. It fit MUCH tighter against the cowl and no further problems. Originality is great, and if you really know how to put the felt on I would bet it would work fine, but the silicon was easy to put in and seemed almost fool proof. I like originality, but not enough to cook an engine.

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                      • #12
                        Who wants to buy the machine to install staples? It’s the size of a Volkswagen van! They are still around, I passed in 2 of them just because I don’t have room. They convert a coil of wire to a staple and it punches through the felt and aluminum and folds the staple in about 2 steps of the machine. Fast for production but not an end user way to do things. Tim
                        N29787
                        '41 BC12-65

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                        • #13
                          Blue Silicone it is, at least it will match the lower color of the plane...

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                          • #14
                            More info and suggestions here:
                            https://c-fclr.blogspot.com/p/taylor...d-cowling.html
                            Scott
                            CF-CLR Blog: http://c-fclr.blogspot.ca/

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                            • #15
                              The early Aeroncas had leather baffles and with the addition of the C85 they controlled the high oil temps with a blast tube to the rear area.

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