Performance with 180hp

Discussion in 'Marquart Charger' started by AaronS, Sep 17, 2017.

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  1. Sep 17, 2017 #1

    AaronS

    AaronS

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    I've been pouring through these forums for a couple of weeks. Thanks to Ian's hosting the plans I was able to download the Marquart Charger drawings and study them a bit, which is really nice to be able to have those available when deciding what/if I want to build.

    From what I could see most Chargers are flying behind some variant of a -320 Lycoming, with an occasional O-300 Continental thrown in for good measure.

    I have a core O-360 that I want to use. I would assume somewhere in the intervening 50 years these plans have been out there that someone used the bigger Lycoming at some point. There is a note on the engine mount plans that the 160/180 hp engines would require Dynafocal mounts, so it would appear those engines have been a consideration in the past.

    Anyone have any first hand experience of how the airplane flies with more HP?
     
  2. Sep 17, 2017 #2

    jrs14855

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    The 0 320 Lycomings come in three different engine mounting configurations. Conical-small tapered bushings-straight mount. Dynafocal Type I- 30 degree bolt angle and Dynafocal Type II- 18 degree bolt angle.
    Any Lycoming from the 0 235 to the angle valve 360 will fit any same type engine mount. Obviously the strength of the mount is a separate issue.
    The Type II engines were mainly used on Piper Twin Commanches. They were all IO engines, IO320B or C.
    If the Charger plans do not show a dynafocal mount the Pitts, Skybolt or Starduster engine mount drawings could be used for the ring portion of the mount, as well as tubing size reference for the rest of the mount.
    If you are overhauling the engine the crankcase shops can convert the case from conical to dynafocal for around $300.
    The extra weight of the 360 should not be an issue. 360 with lightweight starter and alternator should be about the same as 320 with the original heavy starter and generator.
    360 at rocker covers is 1" wider than 320.
     
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  3. Sep 17, 2017 #3

    Dennis5678

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    As you know the original flew well on a O-290 Lyc. What are your
    intensions? Low and slow Sunday flying with an loop or roll thrown in
    once a while? I have notice Chargers with bigger engines the landing
    gear cracks because they are heavy. Lyc O-290's are getting old and to find one in great shape will be a callange. Not that it couldn't be done.
    With a Lyc O-320 you are going to have to watch weight very carefully
    Ed Marquart said it himself with the Lyc O-290 it is a beautiful flying airplane and if you add heavier more HP engines the whole beautiful balance is thrown off.
     
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  4. Sep 17, 2017 #4

    AaronS

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    Dennis, that is one reason I asked the question.

    Honestly I don't know if I would seek out an O-290, but an 0-235 isn't out of the question and they can easily be made to turn out 125 hp.

    I don't plan on anything more than gentleman aerobatics, the occasional loop and roll or a sporty lazy8. Mostly local flights and short cross counties but several times a year a flight of 300 miles or so. And once, before I slip this mortal coil, a circumnavigation of the lower 48, something I never have accomplished.

    The reason for the 0-360 is it is what I have. Engines being one of the largest expenses of building and the fact I know this engine makes me want to stick with it. I already have the light weight starter and alternator, figure I would save a few pounds with an electronic ignition as well.
     
    Last edited: Sep 17, 2017
  5. Sep 17, 2017 #5

    EAABipe40FF

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    Both the O290 and O235 are problematic as regards cost. The best bang for the Buck is probably an O320 with the O360 close behind. I'd go with your O360 and make it work. (I already have an underpowered Acroduster2)

    I love the Charger but I don't like the gear. I'd simply copy an existing bungee gear off a Duster or Skybolt. But to each his own......

    Jack
     
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  6. Sep 18, 2017 #6

    Neil

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    If I had the 360 I wouldn't hesitate to use it. Better to have power you don't need than to need power that you don't have.
     
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  7. Sep 18, 2017 #7

    TFF1

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    i would use it in a second.
     
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  8. Sep 18, 2017 #8

    Beej

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    +1 from me.
     
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  9. Sep 18, 2017 #9

    Hartley

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    I have an O-360 Charger. It is great. Nice take off roll compared to the smaller engines.

    Hartley
     
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  10. Sep 18, 2017 #10

    IanJ

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    The user called "alaskamech" just bought N645, which has an O-360 on it. I wouldn't hesitate to use a 360 if it was the path of least resistance, but I also wouldn't seek one out. If 290s were as common as 320s, I'd be aiming at a 290 on my build, but the 320 will do for my use. I'm definitely of the school that light weight is better than more horsepower, but then I'm also not interested in the kind of flying that requires more horsepower.

    I think you'd be fine with a 360, you just have to pay attention to weight pretty carefully. Ed Marquart put some effort into making the Charger as light a plane as he could, so strict adherence to plans will take you a long way in that regard. I have the impression from vague research that the 360 and the 320 aren't much different in weight, but it's possible that there are other add-on weights that I'm not aware of (engine mount being one such example). I suspect that a 360 will result in a more re-sellable airplane than a 320 or a 290, since many people gauge an airplane by its horsepower, even when that's not the best measure.
     
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  11. Sep 18, 2017 #11

    IanJ

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    Tell me more about this "simply" you speak of. :rolleyes:
     
  12. Sep 18, 2017 #12

    Randy

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    I 100% totally agree with Jack. When I finally took that "#^$&*@#* gear off my SkyBolt I was no where near strong enough to throw it as far away as I wanted to :(:mad:
     
  13. Sep 18, 2017 #13

    IanJ

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    I'm more interested to hear about how simple the change would be. I've looked into it, and it looks to me like it would involve an engineering degree, or way more experience designing airplanes than I have. This is a subject near and dear to my heart, and will directly impact my build in the coming years. What am I missing?
     
  14. Sep 19, 2017 #14

    Lotahp1

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    0-360 is the way to go. I had a 0-320 160hp AcroSport 2 and it was fine and I suspect a Charger has more wing? So maybe even better. BUT the weight difference is not that great between a 0320 and light 0360. Use a fixed Catto, Or Hercules style prop. (Hercules sure has the looks). A 290 or 0300 or 0235 is NOT the way to go. There's no advantages as far as looks, power etc etc. just a little weight savings. If that's the issue, spend the effort and do as Jack mentions...install a Starduster Too style bungee gear setup. Again, you could use the Starduster Too plans to help you figure out how.
     
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  15. Sep 19, 2017 #15

    EAABipe40FF

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    Ian. Not having Charger plans I don't know how simple it would be to stick a bungee truss into the Charger. But nothing is simpler than a bungee gear IMO. I suspect if you acquire a couple sheets of Duster gear plans you will find the engineering pretty straight forward? Of coarse not having actually done it I could be wrong?

    Jack
     
  16. Sep 19, 2017 #16

    Neil

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    I might be more inclined to adapt the Skybolt gear. Seems like a fair number of Dusteers have gear problems. Also enough Firebolts (Charger style gear) have been converted back to the standard Skybolt gear that the road may already be paved.
     
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  17. Sep 19, 2017 #17

    AaronS

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    Right turn Clyde! :D

    Thanks for all the input everyone!

    AFA the rubber donut gear, I've read the other threads. Having lived with an airplane that had them for the past decade I can make one observation, the condition of the rubber is critical to their performance. It cost me $5K to have all three gear gone through a couple of years ago but the change in handling and behavior on the ground was like night and day. The old donuts were hard as hockey pucks. The newer rubber formulations seem to "go hard" between 5 and 10 years based on mine and others experience. As an added bonus the donuts collapse with age. The hard and collapsed donuts transfer all the landing loads directly to the airframe. Damage is not uncommon especially after a "sporty" landing with old rubber on the legs.

    The plans call for Ercoupe shock disks. I don't know about those pieces, but only one outfit makes them for the Beech Mice and the quality varies greatly between production runs.

    Other than replacing them when needed, there is nothing to maintain with the gear save for grease the pivot pins every so often.

    Kind of an apples and oranges since my airplane weights half again as much as a full up Charger does and it's a tricycle, but that's my observations at least.
     
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  18. Sep 19, 2017 #18

    biplanebob

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    My biplane uses bungee cords on J-3 style shock struts. Been flying and maintaining it for 40 years.

    I have noticed over that time period: differences in the lifespan and tightness from one manufacturer to the next (when there were multiple brands of cords) and from batch to batch.

    Bob
     
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  19. Sep 19, 2017 #19

    IanJ

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    The problem I keep running into is that the rear pivot (ie, where the rear leg of the triangle hits the lower longeron) for the bungee gear types is almost always further back than it can easily be placed on the Charger frame. You can see it here, at stations B and B1:

    http://obairlann.net/reaper/aviation/biplane/charger-plans/Sheet%2012%20-%20Fuselage%20Frame.pdf

    That's only 9 inches fore and aft, and every bungee gear design I've eyeballed has more like 12-15 inches between those points. Getting into re-engineering where station B1 hits sounds like a job for someone with more skills than I have, and it would, as you and others have so often argued, ruin the "Charger look."

    I'm not confident enough in my eyeball engineering to know whether a 9" base is enough to support the aft loading of landing gear on a 1550 lb gross plane that touches down at 70-80 mph, when in a bungee configuration rather than a cantilevered leg configuration. I feel like this is one of the points where the "Charger gear sucks" crowd has some justification: that 9" base provides a relatively short lever arm for the braking forces the landing gear has to absorb.

    Sorry for the threadjack, Aaron, hopefully it's helpful in your research, at least.
     
  20. Sep 19, 2017 #20

    Beej

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    I could be wrong, but I don't think the Charger has the same problems with the charger gear like the Skybolt has....
     

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