Pat's build thread

Discussion in 'Marquart Charger' started by pbrannan, May 1, 2018.

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  1. Jun 13, 2018 at 11:28 PM #21

    IanJ

    IanJ

    IanJ

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    Could you add an "arch" that comes to midway up the baggage door to raise the shoulder straps? It would make the baggage access ridiculous, though with a sufficiently strong latch and sturdy hinges, the arch could be part of the baggage door. ;)
     
  2. Jun 15, 2018 at 8:20 PM #22

    Larry Lyons

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    I wondered about the bending force pushing out too. But as its a one time two use jig probably doesn't matter if they do spread a bit.
     
  3. Jun 15, 2018 at 8:37 PM #23

    pbrannan

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    I am going to think about the arch after I get the seat in and see where I think it needs to be. I think what Larry is saying, is that if you hit hard enough to bend it, you have some bigger problems. The only point in raising the shoulder harness is to prevent spinal compression in a serious forward crash.

    I suppose I could put the baggage access on the side. I've thought about that. I'm all for simple.
     
  4. Jun 15, 2018 at 8:50 PM #24

    pbrannan

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    In light of my simple comment above, I've been thinking about the fuel system. I was talking to a guy who owned a Marquart in the past that had a larger fuselage fuel tank and no wing tanks. Given that I'm putting an O-290 in mine, I think it would only take 21 gallons to give me 3 hours of endurance. So If I can get 5 or 6 more gallons in the main tank I would have something on the order of 24 or 25 gallons. This seems like plenty.

    Benefits: simplicity, weight, eliminate fuel management error, lower cg, fewer places to leak, less drag, nicer looks, less work, totally accessible fuel system, ability to use fuel injection without piping a return to the wing if I so desire.

    Negatives: A little less gas, possibly less passenger room, some engineering, structural issues?

    I don't really think there is a safety problem with extra fuel in the fus. Once you have 1 gallon of gas on fire in your lap you might as well have 50. Ideally, all the fuel would be in the wings, but that's not going to happen.

    I've been toying with electronic fuel injection for the engine. I know it's not possibly justifiable in any economic sense and that it's extra work and money. But it's the kind of work that I personally enjoy. The wing tanks make the fuel return difficult.
     
  5. Jun 15, 2018 at 10:00 PM #25

    IanJ

    IanJ

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    I think was Larry was saying was that your bending die might itself bend, but because it's only used a few times, it doesn't matter too much, responding to my comment about how I probably would have put in diagonals.

    I also have given thought to the side-mounted baggage access door. Given the shoulder belt issue (which I hadn't considered before), it makes a lot of sense to do side access to baggage, like a Stearman, and build up an arch to raise the shoulder straps to a better height. I've considered how to make the turtledeck easily removable as well, to simplify tail inspection and maintenance access. I don't imagine having the side-access door there or not would really change how the removable turtledeck would be built, though.
     
  6. Jun 18, 2018 at 11:26 PM #26

    pbrannan

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    My not so great machining skills are getting me again. I am moving my seat back to it's original position. The seat frame is made of 5/8 tube and attaches in 4 places by sliding into a 3/4 inch rectangular tube.

    The original plan is to drill the rectangular tube under size and match drill the seat frame and tube when in place. Other than the fact that this wall thickness rectangular tube is no longer in stock anywhere, that's a fine plan.

    My problem is that my seat was already installed and match drilled. I now have to install it with the seat frame already drilled. So I need to make the rectangular tube match drill from the inside out.

    Does anyone have any idea how to go about this? Drawings are below. The seat frame parts highlighted with red arrows have to fit inside the -488 bracket part.

    Thanks.

    Screen Shot 2018-06-18 at 5.12.21 PM.png

    seat-attach.png
     
  7. Jun 18, 2018 at 11:34 PM #27

    IanJ

    IanJ

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    Could you weld the existing holes closed, so it can be re-drilled from "virgin" material?
     

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