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Airframe Modifications

Aircraft modifications begin on the prototype.

We were holding out to see if we could complete a couple more test flights on the aircraft but the wind speed came up pretty early in the morning and so we abandon ship for the rest of the test flights and have just dive right into the modifications of the EMG-6 prototype.

The planed modifications to the aircraft include, Installation of the tail dragger landing gear and removal of all the other wheels on the aircraft.

Moving the wing sweep back to its original position of 3° aft. This will assist in the center of gravity to allow lighter weight pilots to fly the aircraft without having to ballast the airplane after the installation of the Polini-250. and while we have the wings removed from the aircraft for the landing gear modifications we will install the new streamlined struts onto the prototype as well.

This will probably put the aircraft out of service for at least a week but then we should be back into the air and resume our Polini-250 flight test program.

The wing removal was rather straightforward. Took us a total of about 10 minutes to get the wings off of either side and we just put them upside down on one of the workbenches so that we can remove the wing struts and install the new style struts.

With the training wheels installed on the airplane even after removal of the wings the airplane remains upright without any difficulty.

Next we move the fuselage frame over to the welding station and hung it from the ceiling so that we could work on the lower portion of the fuselage frame.

First step was to install the fittings for the wing strut attach onto the existing cross tube for the landing gear tube. We have a special jig for bending these 1/8 inch thick 4130 chrome Molly steel wing strut attach plates.

Once the plates have been welded in place we cut off the extended axle and weld around the perimeter to the attach plate.

The next step was to install the landing gear attach fittings that are now standard on the production prototype aircraft. The fuselage frame from the prototype to the production prototype has changed slightly and as such those builders that are currently building will notice that the bottom leg of the prototype is a little bit longer than their aircraft.


On the prototype aircraft the training wheels were attached with eye-bolts and since we will no longer be using those we just left the eye-bolt bushing installed and will attach the landing gear to either side. This is how prototype aircraft get to be looking ugly after a while. Enough modifications and everything looks like it wasn’t intended to be built that way.

The existing builders will also notice that the forward section is a little different than on their aircraft as well. There is no open tube that crosses over at the front of the landing gear box area and the landing gear attach tabs would be centered on the cross tube.

The 2 axle tube holders have been cut and are ready to weld to the landing gear assembly.

Because we are testing a different type of wheel we are manufacturing our own axles from 4130 chrome Molly steel .190 wall thickness tube. We have threaded the end of the tube because were going to be using a set of wheels on this aircraft with tapered roller bearings and we will need to be able to tighten up those bearings.

Were going to use some very small 4-inch Grove wheels and the disc brakes from a bicycle that we originally done designed for the EMG-5. The landing gear for the four-inch small tires is going to be modified slightly to accommodate these wheels.

Bending the landing gear Bungee attach fittings. the fitting will now be heated at the bend making a U channel that will be welded to the 4130 down tube.

In this picture here Jason is setting up the landing gear frame using the Jake for the production prototype aircraft. Which is slightly different from the original prototype. But we will adapt to the production landing gear into the prototype aircraft.

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About Brian Carpenter (255 Articles)
CEO Rainbow Aviation / Adventure Aircraft

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