“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.
March 29, 2016 Flight Controls
In this picture here we are wet sanding and prepping the ailerons and horizontal stabilizers for the next coat of poly spray silver.
This will be the last couple of poly spray silver on these services before we start the installation onto the aircraft. This should allow us to get the horizontal stabilizer mounted by tomorrow. And the ailerons in the next couple of days.
The elevators and rudder also got there 1st Couple of coats of poly spray silver.
The surfaces will still need at least one more application of poly spray silver before we can install them on aircraft.
March 28, 2016 Control System Installation.
March 27, 2016 Rudder Gap Seal Design Testing
We have been working on a new 3-D printed gap seal system which we will install on the rudder assembly for testing. And if we like the results we can expand it and incorporated into the ailerons and elevator system as well. Initially the weight associated with the 3-D printed gap seals is about 4 times as heavy as the foam gap seals that we developed earlier.
The gap seal functions by having spring-loaded seals that provide a radius transition from the vertical stabilizer to the rudder. and then use a foam core to position and hold the tension of the Seal against the vertical stabilizer while allowing it to rotate and have it in place as the rudder moves.
The foam core material that holds the Seal in place and acts as a spring is simply backer rod from Ace Hardware which is made for sealing cracks and gaps in household applications for weatherizing your house.
With the rudder positioned 30° off of center to the left the hinge rotates to maintain alignment and provide a smooth transition from the vertical stabilizer to the rudder
And with the rudder rotated 30° to the right the outside legs of the Seal curve to maintain tension against the rudder as it moves away from centerline.
Because of the movement of the rotor spar as it is deflected the distance between the vertical stabilizer spar and the rotor spar gets closer. This is why a solid gap seal cannot be used and why this gap seal function so well as it uses the backer rod as a spring to absorb the tension and maintain position of the gap seal as the rudder repositions. In this picture here you can see the rudder also deflected to the right and still maintaining close contact with both the vertical stabilizer and the rudder spar making for a very smooth transition. This 3-D printed part has been post processed by acetone dipping and then sanded to the final smooth shape that you see in the picture below.
March 26, 2016 Drag Reduction Improvements
We are day might be narrowing in on the completion of prototype #2. We are just now starting to work on the control system for the elevator and ailerons. And we been doing a lot of drag reduction modifications to the aircraft to improve its performance as a glider.
We have switched over from AN bolts on the rear lift strut to washer head screws to reduce the drag profile. The inboard section where the forward lift strut attaches to the fuselage will be fared in with a fairing.
We have made the modifications to the left struts to incorporate an internal nut plate attached to an internal 1 inch tube which is slid down the inside profile of the streamlined strut and riveted in place which allows us to go to a eye bolt attachment system without the eye bolt coming all the way through the other side of the lift strut with a washer and nut protruding into the air stream. This modification was accomplished on prototype #1 previously.
This eye bolt system along with our new 3-D printed fairing set allows us to significantly improve aerodynamics around the attachment locations. one of the advantages of modeling and prototyping with the 3-D printer is that you can continue to modify the product until you have the fit just right. For each one of the fairings we have gone through about 6 different prototypes in order to get it to fit just right.
The forward upper 3-D printing fairing for the jury strut
March 24, 2016
Flight Control Finishing
We now have all of the flight controls and stabilizers finished for the (LD) low drag version of the aircraft. All of the surfaces have now been covered and we are prepping the airplane up through the 3 coats of poly spray silver for UV protection. we will probably end up flying the airplane in silver in order to get some of the test flight program accomplished and then work on the final paint after we’ve done some of the initial test flight program.
March 23, 2016
Control System Component Production
Most of the airframe structure on prototype #2 is now coming together.. The next step will be hooking up all of the flight controls and the control systems to the airframe. We have been working on universalizing the control systems reducing the total part count and simplifying the construction process. One the components that we are producing currently is a tube end connector that fits inside of the 5/8 inch x .035wall 6061 T6 aluminum push-rod tubes. These particular components are designed for one end of the tube that does not have any adjustment. These are manufactured from stainless steel.
We start with the basic bullet that comes out of the CNC lathe.
Then there is a three-step milling process to manufacture the end. This end is designed to work as a fork bolt with a 3/16 inch AN through bolt or clevis pin. the 1st step is to profile the fitting.
T.he next step is to use a slot cutter to machine the fork end
And the last step in the machining process is to drill the 3/16 inch through hole.
And the last step will be to de-burr and tumble the end fitting to get rid of any machining burs that are left.
Covering the Elevators
Jason was able to complete the construction of both the left and right elevator assemblies in a single day and has now begun the process of covering the surfaces with poly fiber glider cloth.
Jason had never done the covering of an aircraft before and after having been through the process on the # 2 glider he has got the process down.
Once you’ve done the covering on a couple of surfaces, you find out how easy it is to do the dope and fabric process.. It’s not particularly fast but this is a process that just about anyone can learn in a very short period of time by practicing on a couple of surfaces before beginning the process of covering the larger surfaces.
March 22, 2016
Elevator Construction Begins
With each one of the sub assemblies I try and give the project to Jason to build it from the drawings without much help from myself. This allows me to identify any misconceptions that may not be clear on the drawings.. The elevator was kind of interesting because I gave Jason just 2 drawings for the entire elevator assembly and because the building construction system is identical to the rudder and ailerons there was very little difficulty in deciphering the plan of attack on building the elevators.
The 1st step in the building process is simply to lay out the elevator spar per the drawings and drill a few reference holes along with the holes for the elevator hinges. The elevator hinges are simply eyebolts that are held in place with a nut plate on the backside of each spar. the next step is simply to position each rib with its reference hole. Use a square to position the rib perpendicular to the spar.. Drill Cleco and rivet each rib in place on one side only.
After each rib half is riveted in place, we rivet the 2nd half of the rib.
We duplicate this process for each one of the 4 ribs that make up the elevator assembly.
The inborn ribs are positioned at an angle and have a reinforcement bulkhead between the 2 rib halves that provide for the control system attachment.
The inboard rib and the inboard rib reinforcing bulkhead receive flanged bushings that will act as the bearing surface for the eye bolt that controls the elevator system.
After all the ribs are in place the trailing edge goes on in the same manner that we did it on the rudder and the aileron systems.
In this picture here you can see the eye bolt hinge that is installed as well as the flange bushing that is JB welded into the reinforcing rib.
once the entire elevator assembly has been riveted on one side the elevator gets flipped over and held in place with lead shot bags while we drill the rest of the structure and riveted together.
And as usual every time that we complete any part we take a weight to validate our final assembly weight.
in the final weight on the elevator assembly with the eye bolt hinges installed ended up at 2.7pounds.
March 20, 2016
We have started the manufacturing process for all the components for the elevator system. In this picture here you see enough ribs for building 2 complete sets of elevators.
March 19, 2016
Zortrax M 200 3-D printer
for the last couple of years we’ve been shopping for 3-D printers. There’s always been a chasm between the usefulness of a hobby printer and the cost of a professional printer. Over the last 4 months I’ve been researching 3-D printers and have come up with what we think is the ideal solution for our needs. Zortrax, is the company that manufactures the 3-D printer that we just purchased. They are a Polish company with a couple of distributors in the United States. The M 200 3-D printer has since its inception been rating number 1 or number 2 on all of the reviews for the last year or so. In the coming weeks you will see us trying catch up on some of our projects that we been holding off on a waiting the purchase of a 3-D printer. I think you will find it very interesting.
The 3-D printers have now come to the stage where we are making usable final end-use products. In the picture below we are manufacturing the 1st go around on the prototyping of a drag reduction fairing for the EMG-6. Some of the great capabilities involve the ability to be able to put a lattice structure inside of a component significantly increasing its strength while maintaining a reduced weight. essentially able to build a honeycomb substructure inside of a part. This is something that we can’t even accomplish with a typical plastic injection molding machine without making multiple parts. In this part here were using a white ABS plastic as the medium. It’s very strong and durable.
Multiple options for resolution of the 3-D printing are available. This is a .014 deposition layer thickness. The Zortrax M 200 is specifically designed for working with ABS plastic. It is a low-cost plastic with a high-strength to weight ratio. One of the characteristics of the machine incorporates an enclosed cabinet with a heated build platform which is essential for printing ABS plastic. During the initial stages of printing a “raft” is created. this is the platform underneath the part that provides a base from which to build the rest of the part.
The raft is easily removed from the rest of the part. The cross structure on the bottom of the part is a support system which builds a support structure underneath the part up until it reaches the level of the actual part itself to be manufactured.
In this case here the fairing is designed to go over the monster 7/16 inch diameter eye bolt on the wing that is used for the wing strut attachment. We have manufactured into the fairing V Notch serrations which allow us to orient the fairing and have it press fit onto the nut at any orientation.
with the fairing install it will significantly reduce the drag associated with that big ugly bolt and nut sticking to the top of the wing. We anticipate that the drag reduction on that bolt can be reduced by about two thirds with this fairing. In the picture below you can see that our 1st prototype was inadequate and didn’t actually fit the contour of the wing like we had anticipated. We will redesign the fairing for the 2nd prototype until we get the fit better than what we see here.
The 3-D printing process is extremely automated however this wing strut fairing that we see being printed here takes nearly 16 1/2 hours to produce. This is simply a prototype that had to be made into sections and will be glued together to test on the aircraft.
The vertical columns that you see throughout the structure are simply there as support mechanisms to hold the model in place during the 3-D printing process. Very hard to print horizontally without some underlying structure to hold that section in place. All of that material simply peels away from the final structure and as with most 3-D printers they have come up with a very unique way of ensuring that the support structures do not stick to the model.
We have been working hard to finish up on the surfaces. In this picture here Jason is doing some of the final touch up before the poly spray silver gets applied to the aileron.
The initial covering of the horizontal stabilizers is up to the stage of stabilizing with a heat gun and the 1st coat of poly brush.
The reinforcing tape and the pop rivets that substitute for the rib stitching have been installed.
Horizontal Stabilizer Streamlined Tubing End Fittings
The horizontal stabilizer is held in place by the streamlined struts material that attaches at the lower vertical stabilizer and runs up to an eye bolt that runs through the spar of the horizontal stabilizer. This streamlined struts has threaded end fittings that adapt to the streamlined strut material. This week we have been CNC machining out the fittings for the horizontal stabilizer and fitting.
This and fitting will be slid inside of the radiused section of the streamlined tubing and then is attached with (4) 3/16 inch aluminum pop rivets
The end fitting is machine from 6061 T6 aluminum .625 inch in diameter
The backside of the fitting is bored out to accept the rivets and to lighten the overall weight of the fitting.
In the picture below the fitting is still without the threads. Fitting will next undergo a form threading process that will put a 1/4-28 thread into the body of the fitting.
March 18, 2016
Horizontal Stabilizer 3rd Rib
The 3rd rib in the horizontal stabilizer is a nonstructural rib. The purpose of this rib is simply to hold the airfoil shape and provide a lower drag profile. This rib is designed to be manufactured from 1 inch thick foam insulation board. for our 1st run we grabbed a scrap piece of foam board from the top shelf with dust all over it and programmed in the airfoil profile into the shop bot.
The 1st pass with the cutting bit simply scores the surface so that we can identify where the screws will go to hold each individual rib and place
In this picture Jason is using sheet rock screws to hold the ribs in place.
After all of the ribs have been cut out, we simply go back and unscrew them from the sacrificial particleboard.
The Finished Rib
Next we will take 400 grit sandpaper and just likely go over the edges and the cut areas to get rid of any loose foam.
The rib is designed to fit snugly into the profile of both the main spar and the leading edge spar.. We simply take a square and make it perpendicular with the rear spar. We will then to take a magic marker and mark the position
Next will will mix up a little bit of the epoxy and epoxy the rib in place. because of the snug fit it won’t take much to hold it in place. After it is positioned any epoxy in place we take the remaining epoxy and coat the entire rib. This will create a barrier around the outside of the Styrofoam which will make it impervious from all of the covering materials that contain acetone and MEK.
We will duplicate the process on the other horizontal stabilizer. it will take about 4 to 6 hours of curing time before we can begin the covering process.
Later in the afternoon we were able to begin the covering process for the horizontal stabilizers. takes about 30 minutes to cover each horizontal stabilizer and get the fabric glued in place with the poly tack.
We were able to get both stabilizers with fabric on them. This will allow us 1st thing in the morning to start shrinking and continuing on with the covering process.
March 17, 2016
The aileron covering process continues. The ailerons have been covered. The 1st 2 coats of poly brush applied. And in this picture here the rib stitching tapes have been installed and riveted to the aileron ribs.
Rather than using the time-consuming process of rib stitching we simply attach the reinforcement tapes to the ribs using aluminum pop rivets.
even the process of riveting the fabric to each one of the ribs is really kind of overkill in this case. More likely than not just attaching the fabric to the ribs using Poly-tack would be more than sufficient.
after the attachment of the reinforcing strips to each one of the ribs and riveting in place we come back over the top of each one of the ribs and cover it with a finishing tape. We will wrap the finishing tape from trailing edge to trailing edge without any seams on the leading edge. This will require only a trailing edge reinforcing/finishing tape
We have started trimming and fitting the fiberglass nosecone to prototype #2.
March 16, 2016
The Fiberglas nosecone layups that we completed yesterday have had 24 hours to cure and we are now ready to separate the part from the mold. We found that during the layup process that it was easier to put the mold up right and be able to rotated as we worked on each surface. With the mold on the ground bending over gets to be pretty old in a hurry.
We only used about 3 layers of lightweight fiberglass cloth. Since this is a prototype we anticipate that there will be some modifications that will need to be done and as a result we wanted to be able to make any necessary reinforcements after we had the shell removed. The goal of course to keep the part very light and only have the strength where it’s necessary on the aircraft.
Took us a total of about 2 hours with 3 people working to complete the layups.
Turns out it was a bit too hot out and we were scrambling to get the layups in place before the resin was kicking off.
In this picture here were using air nozzle to separate the part from the mold. We have some pretty tight curves and very deep draw on the nose cone shell. Probably not enough draft on the 2 inlets. It took a little more than the average amount of work to extract the part from the mold. However it did separate cleanly and left us with a nice finished part.
The finished nose bowl after being removed from the mold. The nosecone will require a considerable amount of trimming before it will fit onto the airframe.
Kristian is one of our part-time workers. He’s very good at detail oriented tasks. In this picture below he’s cleaning up one of the last steps in the manufacturing process of one of the wing fold components getting them ready for bead blasting.
The parts come out of the milling machine leaving a small tab that has to be Sanded off, and the ends of the parts radiused to match the profile.
March 15, 2016 Nose Faring Lay-up
We’ve started doing the layups for the nose cone. This will be our 1st run using the mold for the nose cone and as such we will make it from fiberglass rather than carbon fiber. We anticipate that there will be some changes and some modifications that will need to be made which will be easier to process in fiberglass.
March 14, 2016 Another New Video in the “Building the EMG-6” series
Another episode of “Building the EMG-6”. In this episode we look at the process of marking tubing. Pretty much every component on the EMG 6 uses tubing for construction. In this video we show you how to accurately and easily mark tubing for these applications.
March 11, 2016 New Video
March 10, 2016 New Video
Weighing the horizontal stabilizer after its complete. The stabilizers have been removed from the aircraft and we are now building a 2nd set. We will be using the 2nd set to help develop the builder videos for the step-by-step process. And the 2nd set will also be used on prototype #3.
Each horizontal stabilizer in its completed stage gets weighed. In this case here both stabilizer halves way and at about 3.94 pounds.
March 8, 2016 Aileron Covering
We started covering the ailerons today. 1st step in the process is to wash and clean the complete aileron..
Jason found some regular aircraft Poly fiber, I think it’s 2.6 ounce cloth. and decided to use it instead of the glider cloth. I had taken off the afternoon to take Carol to dinner and a movie because it was our 14th wedding anniversary, Jason could not get a hold of me and he knows how I hate him coming up with excuses for not getting things done. So he just made the decision to use the 2.6 ounce cloth rather than wait and order more glider cloth. When he makes decisions when I’m not around there is not a damn thing I can do except support his decision-making process. I got payback though. the glider cloth is so easy to work with and that’s all Jason had been doing lately, he forgot how much more difficult it was to work with the thicker fabric. He was pissing and moaning about it by the time I showed up later that afternoon..
One side of the aileron glued down with Poly tack.
March 7, 2016 Horizontal Stabilizer Production Continues
March 6, 2016 Horizontal Stabilizer Production
We have started production on the components for the horizontal stabilizer. The leading edge of the horizontal stabilizer requires that we been the component on our production tube bending machine. The machine has to be set up with internal stops built into the machine to been very specific dimensions.
The tube bends have to be calculated for the amount of spring back. As you bend a tube after it comes out of the machine it will flex back a certain amount. The amount of spring back that we have been each tube depends on many variables but primarily it is a result of trial and error and tell we get the exact dimensions that were looking for.
We have a CNC manufactured fixture that both checks the bends for the proper dimension, and also gives us a cut off dimension for each end.
The horizontal stabilizer leading edge at the outboard tipped. The tubing gets marked at the edge of the fixture and that becomes the cut off dimension.
The inboard section of the leading edge will also get cut off at the edge of the board. We use a metal cutting chop saw to cut the aluminum tube.
We will start with 4 leading edge tubes and go through the complete construction process with the before we start bending more tubes. It took us a total of about sections of tubing before we got the bending stops set exactly perfect.
March 4, 2016
For the last couple of days we been working on building the ailerons and updating the builders database and putting together the assembly instructions for the ailerons. You can click on the links below to see some of the progress that we’ve been accomplishing. There are still some tweaks to the drawings and the assembly instructions but they are complete enough at this point in time to see how the process goes.
Link to the assembly instructions for the ailerons spar assembly
Link to the assembly instructions for the ailerons
Just going over some rough numbers on the aileron construction. Solid Works has calculated that there is 1938 in.² of surface area per aileron. That’s about 13.5 ft.² Our final weight on the aileron was 5.4 pounds. That gives us a final weight per square foot of about .4~ pounds per square foot of surface area. Of course we still have to cover the aileron, add 4 hinge bolts, and the aileron control horn.
March 3, 2016
March 2, 2016
Horizontal Stabilizer Forward Socket Part Number 55-21-41
A close-up view of the fitting before the machining processes been complete. The cross hole that attaches the inboard compression strut is still yet to be machined.
March 1, 2016
We have been working on the modifications to the rudder control system to accommodate the shortened rudder pedals. one of the design criteria for the airplane allows for the modification of the control system and seating to adapt to different size pilots. When we get to the very short pilots we have the option of moving the rudder pedal attachment location aft to assist in making the controls more comfortable. With this modification we need to add an idler arm into the rudder control system in order to assist with the clearance of the rudder pedal control push-rod Tube
The two idler arms are manufactured from .040 4130 steel.
After the idle arms have been powder coated the powder coating needs to be removed from the inside in order to accommodate the nylon bearings.
The nylon bearings inserted into the idler arms.
With the idle or arms in position along with control stick bearing shaft we are positioning temporary push-rod in order to adjust and test the push rod tube lengths.