Fuselage

Today I moved on to the flap drive system. I like mechanisms so this is where the fun really starts. The RV4 was originally designed with a manual flap system, however it has some draw backs, in particular its effect on passenger comfort. The electric flap system is therefore an option which was designed in afterwards. As you can see it uses the same flap drive mechanism as the other RV, but has an interesting lever system in view of the limited space.

In this picture you see the drive mechanism on the RHS partially extended; perhaps 10 to 20% of its range. The fixing on the LHS is a pivot point. About 1/3rd of the way along the lever you see a bearing which when the flap motor causes the mechanism to contract moves at about 1/3rd of the rate with 3 times the force. This pulls on a lug attached to the flap actuator (black) and in turn will cause the flaps to be deployed when it is all connected up. The points to watch when you are installing this are that you don't let the motor get too high. The problem this causes is the drive mechanism when fully extended is very close to the floor. I have a shim under the white nylon guide block you can see on the RHS. This will I think ensure the bolt head never touches the floor.



Here the camera is nearly on the floor, looking aft. You can see the same bearing on the lever arm and the lug hanging down to which it will connect.

You can also see something interesting which is nothing to do with the flap mechanism. Projecting forward towards the camera is my solution to the rear passenger 5th point seat belt attachment point. Its not ideal in that the pull will be vertically upward, but I think it is quite beefy enough to do the job. It will need a thin shim between it and the underside of the cockpit floor.

There are quite a few 2 man jobs involved assembling this since some of the brackets need riveting on from underneath the fuselage.