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    by Published on 03/14/2010 04:41 PM
    1. Categories:
    2. e Chapter 6 - Fuselage,
    3. l Chapter 12 - Engine/Propeller
    Glassing new NACA runner side ducts to runner

    Here you can see we've added angled ducts to the sides of my NACA runners. I hope to do two things here, well, maybe three. I don't want to suck rain (1) into the engine, so I was moving to the side discharge. I would also like to get better ram air flow (2) into the motor, so by taking a more direct route to the new air cleaner, and expanding the duct closer to the NACA (3), I think overall flow will be much improved. We'll probably never really be able to tell if any of that is true, but I like it better. Some additional information on the runners can be found here.


    Runner side ducts
    ...
    by Published on 03/10/2010 05:44 PM
    1. Categories:
    2. e Chapter 6 - Fuselage,
    3. l Chapter 12 - Engine/Propeller

    So, we're building this new cooling plenum. My engine always cooled fine, but I had issues iwth the runner to NACA junction and the plenum was a little fragile the way I had cut the built the runner-to-plenum junctions. I also wasn't very happy with the wire grommet or spark plug and oil filler access. I'm planning on installing a pop-up oil door in the plenum (or similar) rather than the yogurt cup bump-down. That always required me to take out the oil cap to remove the plenum, which I didn't like and felt was putting junk into the egine, and cup size was hard for me to get my fat hand into. Also I think it messes up the airflow out of the runner into the engine. As we were looking at the runner connection to the new plenum we got the bright idea of trying to bond the new "back-half" runner to the plenum since we'll have a convenient break point there. We tested this by glueing them to the plenum and that seemed OK, so I glassed them down. Well, guess what. It doesn't really work, it's just too stiff to get down and fitted (and the weight of the runners makes it too bendy. Nice. So, off they come. We'll be going back to the factory-style solution.
    by Published on 03/07/2010 05:45 PM
    1. Categories:
    2. e Chapter 6 - Fuselage,
    3. l Chapter 12 - Engine/Propeller

    Here you can see we've extended the cooling plenum onto the engine. You can see we've used my buddy Andy's trick of waxing the engine so the glass doesn't stick. Andy has gone to a bunch more effort to seal off his engine, but since we didn't have cooling issues before, and we expect our changes will improve our coolign, I'm not going to bite off those changes yet.


    Rear extension of new engine cooling plenum to engine casing

    Rear of engine plenum

    Dry fitting the new NACA diversion ducts under cowling

    Naca Ducts - Combustion and Oil Cooler
    by Published on 10/09/2009 04:54 PM
    1. Categories:
    2. e Chapter 6 - Fuselage,
    3. l Chapter 12 - Engine/Propeller
    Forming foam for the NACA runner diversion duct

    The runner modifications are nearly done now, the hinges are on to mate the two halves together, and the stubs are firmly bonded to the fuselage. The only thing remaining is to add the new ducts for the engine and oil cooler on the side of the runners.



    Forming the duct
    ...
    by Published on 10/03/2009 04:59 PM
    1. Categories:
    2. e Chapter 6 - Fuselage,
    3. l Chapter 12 - Engine/Propeller

    We've moved both the engine air intake and the rear oil cooler intakes from the bottom to the sides, and have made slanted pick-ups that should improve the airflow.


    Glassed NACA runner diversion duct


    Since the premolded engine cooling NACA ducts don't seem to be covered elsewhere in the manual, I'll include them here. Much of the cutting was completed during Head Start, though I did cut the overheard fresh air duct at home. Then they're all fitted up and held in place. The engine naca's had been set with pop rivets for the trip to Ohio, which was sufficient. The fresh air naca was set with glass bubbles and held with tongue depressors. Then all three were given a radius underneath with the aforementioned glass bubbles, and then layed up with BID. Fairly straightforward, though somewhat time consuming, but I just love the more "visible" changes to the plane. Also note that all three got a fair amount of sanding once they were cured. The fresh air naca needed to have the premolded section sanded down to the roof line, which was fairly simple. The large engine naca's, however, had a definite tilt to their flanges that made them visually pucker in comparison to the roof line. I filled the offending area with microballons and sanded, filled and sanded, and got to something I think is close. I will probably cover this area with Cabosil later for wear. Also note that the fresh air scoop needed to have it's inlet ramped back into the fuselage roof for good flow, and this area was covered with microballons and BID.

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