Modifications for the Marquart Charger

Posted September 12, 2016
Updated December 12, 2017

The Marquart Charger is not a perfect design, and as I read more, I occasionally find suggestions for modifications that might be made to improve the plane. Finally, the list is long enough that I'm afraid of forgetting some of them, thus, this list.

Things which would improve the Charger design:

• Reinforce the fuselage around the landing gear attach points.

  The fuselage tubing in the area of the landing gear attachment points has been identified as being potentially under the necessary strength. Using thicker-walled tubing in this area is recommended.

• Extend gussets on landing gear pivot tube, on the gear legs.

  Glenn Gordon experienced gear problems (detailed here) that eventually led him to extend the gussets on the landing gear pivot tube to reduce the bending moment on the pivot pin. He also replaced his existing solid pivot pin with a new solid pin, rather than using the plans-specified tube.

• Add gussets to the donut support washers on landing gear struts.

  As detailed at the end of this thread, adding gussets to the struts to transfer some of the load from compressing the donuts will prevent weld failures where the donut support washers attach to the strut.

• Or, just convert to Grove spring gear.

  Another landing-gear option is to convert to Grove spring gear. This would require fuselage modification to work properly.

• Use larger spoked wheels for a "vintage" look.

  I quite like the look of the Airdrome Aeroplanes Heavy Duty Wheels. I'll be interested to see how they look on the Charger.

• Modify rear seat position and size.

  I am a relatively large person, and would probably benefit from having the rear seat moved back 2-3", and the seat widened.

• Add U-channel in cockpits for wiring.

  Reference Remo Galliazzi's Charger. It has a 3" wide, 1" deep aluminum U-channel running down the side to carry wires and pitot/static tubes, making the wiring very clean and easy to trace.

• Extend hinged aluminum side-panels to rear cockpit.

  The plans call for a hinged aluminum side-panel to extend to about the instrument panel. Extend this hinged paneling to the back of the aft cockpit to facilitate maintenance to systems in the pilot's area.

• Modify control system to use needle or roller bearings.

  The control system can be enhanced by the use of lower-friction bearings.

• Modify in-wing aileron bell-cranks to reduce slop,

  See this comment for more information.

• Modify elevator trim to use a trim tab instead of jackscrew.

  The jackscrew system has some advantages, but is heavy and comparatively complex. Trim tabs are simple and light, but have to be correctly designed to avoid flutter.

• Make turtledeck removeable.

  Using a carbon fiber or fiberglass and foam sandwich structure, make a one-piece molded turtledeck that can be covered in fabric, yet still removeable via screws or Dzus fasteners, to simplify tailcone maintenance.

Created by Ian Johnston. Questions? Please mail me at reaper at obairlann dot net.