RE: DH 2
Okay, it's been a while since I've posted but progress has been happening! Also it got to be prime flying season with Ohio Dawn Patrol in July, then our club's giant scale fly-in & the Hoosier Dawn Patrol in August, so I certainly wasn't working on this on those weekends.
The fuselage nacelle is coming together as you can see from the pictures below. I wanted to try dual elevator servos. The DH-2 used external control horns at the front of the nacelle to drive pull-pull cables back to the elevators. The plans for this model had those two horns connected to a single axle that was itself driven by a single servo. To achieve dual elevator servos, it seemed simplest to mount them to the side walls, do away with the complexity (& failure modes) of an axle / pushrod arrangment. I purchased servo shaft extensions (with 6-32 hubs) from servocity.com. Those allow the control horn to be mounted externally & a direct drive back to the servo. The servos are mounted to hardwood blocks, epoxied to the inside walls of the nacelle with the hub & shaft extentions protruding through the walls.
The cabane struts are mounted to 1/4" thick aircraft plywood blocks, inset from the fuelsage side wall the proper distance These struts are simply cut from Proctor streamline wood struts & bolted to their mounting blocks with a pair of 2-56 socket head capscrews & blind nuts.
The engine will mount directly to the rear firewall, itself made out of 1/4" thick aircraft plywood, reinforeced with triangular hardwood gussets. The other formers are made out of 1/4" thick lite ply. I'm using an OS aluminum engine mount, so the firewall has been drilled for that & blind nuts installed to fit the bolts that came with the mount. The mount is designed by OS to fit their FS 155a 4-stroke glow engine. This engine uses a pump (which is something I've not used before on a glow engine). I plan to mount it inverted, but the mount is reversible if I need it. In this photo, you can see the plywood tray I made to hold the fuel tank betwen the firewall & the middle former. I'm going with a 16oz Hayes tank.
Next step will be to start laying out cable routing & finalize servo location for the rudder. Also next up will be the creation of the fiberglass nose cap.
-Greg