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EMG-6 "Shop Notes" June 2016

“EMG-6 Shop Notes” is a day-to-day accounting of what’s going on in the shop with the EMG-6 Electric Motor Glider.

June 29, 2016 Aft Fuselage Enclosure

we have finished the lower wing gap seals and are now proceeding to enclose the aft cabin area. The aft fairing will be covered with poly fiber covering just like the rest of the aircraft. The area from the aft fairing and aft fuselage bulkhead to the forward fuselage Bulkhead will be covered with a removable background sailcloth covering. We will be installing a window into this panel.


The passenger area cover will be installed with snaps and Velcro attachment for easy removal and re-installation.

A look at the snaps that will hold the cover in place.

Jason is covering the aft fuselage with stents poly fiber covering.

 

June 28, 2016 New Video

 

 

June 27, 2016 Keychain Project

A little project we made up with the 3-D printer to give out as gifts.

June 26, 2016 Lower Wing Gap Seals

Jason’s been working on the lower wing to fuselage fairing strips.

These a been kind of tricky because of the compound curve created by the lower surface of the wing in conjunction with the curve of the fuselage.

This was basically an exercise in trial and error to finally get the fit just right. We have made templates for the  this process to help in the future.

The lower wing Seal fairings working in conjunction with the aft fuselage fairing. As a result we’ve had to remove and install the aft fuselage fairing multiple times during the fitting process.

 

June 25, 2016   3-D Printed Strobe Light Receptacle

Over the last couple of weeks we’ve been slowly working on the strobe light mounts for both sides of the nosecone. These are a 3-D printed part that are designed to fit into the existing cut out in the nosecone. Because of the size of the strobe light mount we were required to make them into pieces. they are 3-D printed from ABS plastic.

Once both parts of been printed we will glue them together using acetone and melting the 2 surfaces and then a joining them during the curing process.

Once the 2 parts of been glued together we can start sanding the outer surface of the component. Because of the grain of the 3-D printing there some areas that leave a fairly rough surface during the printing process. We’ve developed a very neat process that we will be doing a video on for post-processing  the ABS parts. we sand the part but do not remove the ABS sanding dust. We then take a smooth paintbrush dipped in acetone and very carefully melt the sanding dust into the part acting as a filler.

This will render the part very smooth and shiny.  any of the joints that have been previously sanded can still be seen however after primer is applied all of the joints and roughness of the surface disappear entirely.

With a single coat of primer you can see that the part is basically ready for paint.

One of the added advantage of using our acetone blending method is that it leaves the part tacky and receives paint and primer very well creating tremendous adhesion.

We even 3-D print the part number into the component during the manufacturing process.

The next step was to create a template for the plexiglass lens cover that will cover the strobe light. Because this is a nonlinear compound curve the ability to extract a template from solid works was too difficult. As a result we were relegated to trial and error until we came up with a template that fit perfectly. Number13 was the winning template.

Once we had a 3-D model of the lens cover we then generated a drawing for the builders database that can be printed at 100% scale. Then we simply spray a little bit of contact cement onto the outer covering of the piece of  Plexiglas and attach the drawing directly to the Plastic. We then use a bandsaw to rough cut an outline around the template and then using The disc sander Sand the Plexiglas lens to the final dimension.

After removing the protective covering from the Plexiglas we then superglue the lens cover into the recess inside the strobe mount.

We use a gap filling slow cure superglue from the hobby shop to accomplish this. Superglue and Plexiglas are not very compatible and as such we use very small amounts to simply hold it in place until we get to the next step.

Once we have the Plexiglas glued in place we mask off the perimeter joint from the 3-D printed housing to the Plexiglas given a white scuff with sandpaper in preparation for the next step.

 

We then mix up some PRC 1422 basically fuel-cell sealant that works really well against Plexiglas. It has great adhesion properties and will seal the joint between the Plexiglas in the 3-D printing housing. The shelf life on the PRC 1422 was passed up about 6 years ago. It be interesting if it actually cures.

Next in the process is to cut and fit what we call the “nostril” on the forward fairing. this is pre-molded into the mold we’ve made. We simply need to trim the excess fiberglass.

In this picture we show the nostril located on the left side of the fairing temporarily in place. 2 good idea to trial fit all of these parts before you  start to finish work.

 

June 24, 2016     3-D Printed Hubcaps

We have finished manufacturing and installing the new 3-D printed hubcaps. We have tested about 4 total different configurations of hub cap. Installing a simple hubcap can significantly reduce the total amount of drag because of the big indentation around the wheel assembly.

The outside of the hubcap. The whole is located so that we can service the tire with a valve stem extension. The outside has been post-processed and primer ready for paint.

In this picture we see the orientation of the valve stem extender sticking through the side of the hub cap.

We are using four-inch extenders that we purchased online and then didn’t realize that the end was free swiveling and would not allow us to screw on the extender from outside of the hub.

Our solution to the problem was to coat the swiveling end of the valve extender with JB weld.. We then chucked up the rest of the extension in the cordless drill and let it run while the JB Weld was Curing.

To secure the hub cap to the wheel assembly we simply applied four dabs of  silicone RTV to the hub And glued it to the wheel half.

The right wheel with the 3-D printer hubcap installed in place. It’ll be interesting to see if the small amount of silicone RTV glue will hold them in place during rough operations.

The Left wheel hub cap being installed.

 

June 22, 2016   R/D Motor Installation Begins

We have begun the installation process of the R/D motor. remember the design criteria that we have the motors be able to be plug-and-play. The standard installation method simply involves installing the motor sub-assembly into the airframe and securing it with one bolt.

Before we can install the R/D motor we needed to trim away a little bit of the excess material from the aft fuselage fairing to provide clearance for the new larger motor.

A view from inside of the aft fuselage fairing assembly showing the positioning of the motor mount shaft in conjunction with the flight control pushrods  and rudder cables.

You’ve got to love and electric motor for its simplicity and lightweight..

The motor mount shaft that was 1st installed was cut with extra length so that we could take measurements in check for clearances before we made the final cut.

This  propeller that we have installed is one that we made specifically for  this motor however we are still waiting on a propeller from China that we think we will use instead of this one.

We have a fiberglass spinner that we will be installing once we have the final decision on the propeller that were going to use.

We are starting to finalize the installation of the wing gap seals on the bottom of the wing  that transition into the forward fairing and the aft fairing.

Jason is filing away on the final fit of the lower wing fairing before final installation

This is the template used for  forming the angle On the lower fuselage fairing in order to obtain the proper geometry for the aft fuselage covering.

We continue to make progress on the paperwork for the airworthiness certificate and have been completing all of the small details. In this picture here you see the N number and the data plate installed

 

June 20, 2016

We have a temporary tube installed in place of the motor mount shaft.. We’re getting ready for the  installation of the R&D motor  assembly. We have a few more modifications that we have to do to the aft fuselage fairing in order to support the weight of the R&D motor. if you remember from previous blogs our whole goal was to be able to make all of the  electric motor systems as modular plug-and-play systems into the aircraft. When we started off with the little Plettenburg Predator 37 motor. this whole motor mount system was way overkill. The motor mounting system that we have designed  is capable of holding up to a 50 pound electric motor assembly. The R&D motor will weigh in at about 25 pounds.

We finished machining the forward end of the motor mount tube support assembly.

 

This picture here shows the motor mount tube bolted in place on the aft bulkhead  cross member. the loads on this end of the motor mount shaft are about 1/10 of the load on the motor side.

Once we have properly position the motor shaft tube and clamp the fitting to the rear bulkhead we can remove the temporary shaft and prepare for the installation of the R&D motor.

 

June 18, 2016

We made some more progress today on the R&D motor. In this picture here we have the 4130 Crome-Molly steel motor mount shaft installed on the rest of the motor mount.

We drilled the 1st hole in the motor mount hub assembly using the CNC mill. Then we use the V block in the drill press to drill the center hole through the entire tube. And then we use the tube as a guide to drill through the other side of the center hub.

Once the center hub is bolted to the 4130 shaft we can start assembling the individual segments around the perimeter of the hub. They are installed with AN4 bolts.

Currently we have a very long piece of shaft material that will be cut off to about one third this total length.

This Solid works drawing here shows a cross-section and the reason why we needed to extend the hub forward to clear the 4130 shaft.

The other end of the 4130 shaft will be bolted to the cross member on the fuselage frame assembly.

We begin the milling process for the Shaft mount assembly.

About 4 hours a machining time.

And were getting close to the final product

One of the other projects we been working on for the last week are designing hub caps to cover the main wheel. These will significantly reduce the total amount to drag on the wheels. We have been playing around with 3-D printed models of the hub cap. I think today after about version number 9 we finally got one that we like.

The finished product as it came out of the 3-D printer. It is printed with the outside down so that we can and all of the ribbed material and reinforcing material to the inside making it easier to extract from the 3-D printer support structure. The vertical hole is a reinforcement around the access hole for the valve stem. We will simply use a valve stem extension to fill the tires.

Printing in this orientation allows you to separate the part from the support structure very easily. On the right is the leftover support structure and on the left is our hubcap.

We were able to use solid works to determine the center of mass for the final product. By adding the reinforcing flange around the access hole to the valve stem we were able to balance the mass exactly in the center of the hub So that when it spinning it does not contribute to an out of balance condition with the wheel.

During the printing process we have The internal Lattice structure fairly broad In order to reduce weight on the final product.

The final product with a heavy coat of primer weighs in at about 2.4 ounces. This is an obvious advantage considering the amount of drag but this simple hubcap will reduce

 

June 17, 2016

We were able to finish up the prototype  motor mount for the R&D motor.  The mounting tube that’s coming out of the motor mount is simply a temporary aluminum tube.  This will be a 4130 Crome-Molly steel tube that  transitions through the rear fairing aft bulkhead into the fuselage frame. It will be reinforced at the attachment location.

In this picture were machining the aft side of the center hub assembly.

The aft section of the motor mount hub is designed to be able to provide clearance for the motor prop shaft nut that sticks out of the rear of the electric motor.

The outer segment being machine from .375 6061 T6 aluminum.

The motor mount is manufactured from 6 outer segments and the center attachment hub.

A side view of the  motor mount attach to the motor.

Jason was also able to get the lower wing gap seals installed temporarily so that we can start forming the lower angle that will be riveted to provide a transition area from the forward fairing to the aft fairing.

 

We have started work on the Polini installation into the aft section of the fuselage on prototype #3. Right now we just got it Kong so that we can start figuring out how to make the fixtures to lock it more permanently in place so that we can start the motor mount construction.

 

June 16, 2016

Jason has been working on fitting the lower wing to fuselage fairings.

Since we now have a dummy electric motor hear from R&D we can begin the installation and mounting process. In the picture below we begin the manufacturing of the motor mount. Undergoing the 1st finish cut

In this picture we are drilling the holes for the attachment arms that will transition from the center motor mount tube to the motor.

 

June 15, 2016

we have been working on the certification of the aircraft and completing the tasks necessary in order to issue the airworthiness certificate to the aircraft. One of the requirements is the word “EXPERIMENTAL” into its letters at the cabin entrance.

This meant that we had put one on either side

We set up the CNC Milling machine and Used it to engrave the aircraft data plate.

 

June 13, 2016 Weight and Balance Day

The airplane is basically ready to fly. we are still waiting on the aircraft registration to show up from Oklahoma City. We have on order the and numbers to be placed on the aircraft. And we have a few more placards and then we can finish up, So as part of the certification process we are conducting a weight and balance on the aircraft.

1st step in the weight and balance process is to level the aircraft. We use the bottom forward section of the fuselage boom assembly as the leveling point. Then we plug-in all of the aircraft scales and warm them up. After warm-up. We 0 the scales and then place them underneath the main wheels and the tail wheel.

we then take readings for right left and tail wheel positions. We then remove the aircraft from the scales and then re-level it. Then using a plumb bob, chalk line, straight edge etc. We take dimensions for each one of the wing points as well as the datum which is the leading edge.

Before we weigh the aircraft everyone in the shop gets to guess at what the weight of the airplane will be. O course I won that one. During the design process I had anticipated that the new design would weigh 315 pounds empty weight. and the weight came in at 302 Lbs. So we were pretty happy about all of that. This airframe is quite a bit different than the ultralight version that we flew on prototype #1.   Everything’s a trade-off. as appear glider this’ll put us in the air and just slightly over 500 pounds gross weight.

 

June 12, 2016

Late night with the EMG-6. We’ve had some good sunsets lately.

We have been finishing up on the instrument panel.

The ballistic parachute handle as a safety pin that is installed anytime the aircraft is not preparing for flight.

We have manufactured a small placard that can be used for holding the BRS safety pin during flight. Serves 2 purposes, 1st a reminder to pull the BRS pin before you begin flight. And 2nd someplace to put pin.

With the BRS installed in this location it also becomes a reminder to reinstall it after flight. this is really important when you ave an aircraft at an air show. Kids and even adults just grab and pull on stuff. Although the BRS rocket motor is pointed above the aircraft firing it off would be a rather expensive endeavor.

Now that we are getting close to finishing the aircraft and ready for certification we have to start worrying about all of the regulations. Every item on the aircraft that has a function or an action requires that it also have a placard that goes along with it. The brake handle lever mounted on the left-hand side of the aircraft is no exception.

T brake handle with the placard which is manufactured to clip on to the brake handle and be position wherever it’s convenient. We will also have to have one more placard for the total release handle which will go right in front of the brake handle placard.

More pictures at sunset.

 

 

June 11, 2016

The EMG-6 2016 T-shirts are now ready for pre-order on the web store. First orders will ship in about two weeks  Click Here to Visit the EMG-6 Web Store

 

June 11, 2016

We have posted a couple of new videos to the YouTube channel.

 

 

June 10, 2016

Every day I check the FAA registry to see if they have issued the registration  for the aircraft. And a couple of days ago we received notification that the N number has been assigned as N751ZB.  We can now install the transition segment at the top of the instrument panel  that transitions into the radio  mount. This is all good news because we will be able to do certification on the aircraft as with soon as we receive the registration hard card in the mail. There’s only a few things left on the aircraft before we can begin the Flight test of prototype #2.

 

With the transition from the radio rack into the instrument panel were now nearly complete with the new instrument panel..
 

Jason is currently working on the wiring harness and hooking up all of the instrumentation and electrical system to the aircraft.

We finished making all of the 3 printed trailing edge fairings for the landing gear legs.

The trailing edge fairings for the round tubes were modified to be able to interface with other existing tubes to provide a smoother transition.

 

The nosecone  sides receive a reinforcement strip along the perimeter to stiffen the nosecone  and make it less susceptible to damage.

Once the reinforcement strip is installed along the nosecone becomes very rigid..

Part of running the wiring is to install a coaxial cable extension up to the radio.

 

June 9, 2016 R&D Motor

Today we had a meeting with Ed Donovan owner of R&D cable. Ed and his team are developing an electric motor that will be used on the EMG-6 electric motor glider. The design parameters are basically to design a 20 hp continuous operating motor turning at 2500 RPM and producing approximately 65 foot-pounds of torque. We will be spinning a 48 inch diameter propeller. this motor is simply a dummy motor that does not have the winding’s and magnets inside but was delivered so that we can use it for the development of the motor mounting system on the EMG 6 as both as a pusher and as a tractor on the to the wing pylon locations.

The bolt pattern is the standard two-stroke Rotax engine bolt pattern. the bearing is the same as the front bearing on the Rotax E gearbox. The total motor weight will be in the neighborhood of 25 pounds when completed.

There are 6 mounting locations on the rear of the motor housing. During testing at full power  the outer housing gets slightly warm but the winding’s and the magnets remain cool even at full power operation. They are still undergoing some operational tests on the motor and perfecting the final design before going into the  mass production phase and developing the tooling for the stamping dies for the winding core. The expectations are that the efficiency of the motor will exceed 95%.. And reliability and durability are one of the key components in the development of the motor. I would expect that this motor will have a TBO in excess of 10,000 hours. And overhaul cost will be the replacement of 2 bearings. We have been told that we should expect to have a operational motor available for installation before we depart for the Oshkosh airshow.

 

June 8, 2016 The Fuselage Assembly Begins to Take Shape

As we start to reassemble the fuselage it begins to take shape. Most everything that’s taking place right now is simply detail work.

All of the gap seals have now been created and installed. We should have a video on the Seal manufacturing process in the next couple of days.

The modified instrument panel now installed. our last instrument panel was mounted slightly different and didn’t provide A good enough angle to view the instruments. We have pushed the estimate panel back inside of the forward nosecone and mounted it to the standard instrument mounting location.

In this picture here we can see the static instruments teed into the static system accumulator mounted to the forward bulkhead

 

June 7, 2016

After painting many of the components on the forward fuselage assembly we are now in the reassembly mode.

The pilot seat back sheet-metal is being installed. Lightning holes will be put in the seat back later.

One half of the static system accumulator.  the other half is identical and will be glued together in the center section in order to form an accumulator for the static system. The simply takes any surges in static pressure out of the system making the digital instruments more stable.

The accumulator mounted to the forward bulkhead close to the static instruments.

 

June 6, 2016 More Fuselage Welding Jig Kits Going Together

We continue to assemble and put together fuselage welding jig kits. We have several new customers that are interested in beginning the process of building the fuselage frame  welding it themselves.

Each one of the components for the welding fixtures are manufactured from a high quality maple plywood and then are branded with the EMG logo.

The branding process is accomplished fairly easily. We have a logo that is CNC machined in reverse which we heat on our shop stove.

The brand is then placed into a small arbor press which Smashes and burns the logo into the welding fixture.

 

June 5, 2016 Progress

The instrument panel layout ready to be installed into the aircraft.

 

The modifications to the fuselage frame completed and prepped for painting..

Paint repair completed on the fuselage frame.

The fuselage keel components being repainted white. We are using a two-part polyurethane paint for durability.

Jason having do remove the paint from the lower section of the keel because of a paint defect during the Spraying process.

lower keel now repainted.

The keel assembly reinstalled onto the airframe after painting.

Now that the keel has been painted and all of the other components on the forward fuselage assembly have been installed we can reinstall the freshly primer nosecone along with the instrument panel.

 

June 3, 2016 Manufacturing Flight Control Gap Seals

We have been working on the tooling for cutting the rudder gap seals using pool noodles through our cutting dies. We finally achieve the results that we were looking for with version number 9. we manufacture the cutting dies from 6061 T6 aluminum .375 inches thick with a 60 thousandths inch cutting edge milled to a knife edge of .015 inches.

We then assemble the cutting dies for simultaneously cutting all 4 sides of the  gap seal. We attach that to a guide block on the inlet side of the aluminum dies. Then we preheat the aluminum dies with a propane torch so that when we slide the pool noodles through the die they cut and seal simultaneously.

The exit side of the dies showing the accumulation of cut pool noodle foam after cutting approximately 10 individual gap seals.

The residual material left over from cutting the extruded pool noodles into gap seals.

The Pool noodle gap seals can simply be pressed in between the rear spar and the aileron spar creating a full span Seal that provides a smooth transition from the wing to the flight control.

Our universal seal that we have finally developed will also work on both the Rudder and elevator flight control systems as well.

The underside of the aileron showing the pool noodle under deflection. The foam simply conforms to the shape of both spars.

 

June 1, 2016

We begin the month of June making daily progress. we had to remove the keel once again and stripped the paint from it and will have to repaint it one more time. The quality of the  paint  job just wasn’t up to our standards.

After using paint stripper and Scotch brighting,  we were back to the same place we were about a week ago with the keel tubes. we will use a two-part polyurethane paint this time which should work much better than the rattle can that we use before.

Jason has been putting together more subassembly kits to be shipped out.

After prepping and powder coating the rudder pedals we installed the nonskid tape to the centers. Will improve both the functionality and the aesthetics.

We ordered new tires for the prototype #2 that we will install after the flight tests have been completed but before we wrap the airplane up and get ready for Oshkosh.

The old instrument panel system is coming off of the aircraft and we are installing the new instrument panel that will tie in with the nose cone assembly.

The new instrument panel will allow us to combine several of the systems together and also strengthen the nosecone bulkhead

The backside of the Instrument panel.

By redesigning the nosecone upper support (3-D printed bulkhead) we can now directly tied the instrument panel into that bulkhead making it removable for maintenance.

We have been working on an article for the sport aviation/experimenter magazine dealing with increasing the strength of 3-D printed parts. These are 3-D printed dog bones that we applied into our attention tester and gather data on different printing orientations as well as different postprocessing scenarios. We will have more information on this in the future.

 

Back to Shop Notes for May 2016

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

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