February 20, 2017After we finish welding the Polini 250 motor mounts we have to protect the tubes from corrosion.
Here you can see where we have removed the self etching primer before welding. This leaves the frame susceptible to corrosion.
We have also drilled pressure relief holes. These help prevent pressure buildup inside the tubes as we weld them. If the pressure is allowed to build up it can cause the weld to blow out.
This is an image of the forward Polini 250 motor mount. Again you can see that we have removed the self etching primer that we use for corrosion protection.
Here we are removing any surface contamination from the welding process with a Scotch Brite pad.
Here is a closeup of the cleaning process. We are using a self etching primer to protect from corrosion. Because this primer will be removed for future welding, epoxy painting, or powder coating. We will not use a surface prep or wash the frame at this time.
Here we are applying the self etching primer.
Here is the forward mount after coating it with primer.
In this photo you can see we have left the pressure relief holes. These will be welded up when we are completely done with any modifications to the frame. We will do a final inspection for pressure relief holes before we paint or powder coat the frame.
February 14, 2017We've begun work on the drive system for the Polini 250. In the picture below you see a preliminary drawing of how the drive system might look. We've been talking for a long time about the max moment of inertia problems associated with the Polini 250 swinging these large heavy propellers. One of the great advantages of the EMG-6 is not only that we use a small moment of inertia propeller but we believe that the introduction of the additional shock dampening drive system should improve the life of the gearbox substantially.
We are utilizing the verse-a-mount shock mounts that are readily available from McMaster Carr. One of the design criteria that always place for mount in the design decisions is how to keep the cost of the aircraft reasonable. Having existing off the shelf components, especially for consumables, is very important.
The shock mounts come in a variety of different durometer configurations. We have purchased 3 different sets of shock mounts for testing purposes. We will probably start off with the softest rubber first and then if we notice excessive wear we will go to the next size up. The softer the rubber the less vibration we should encounter.
The moment of truth. One thing that we couldn't easily verify in SOLIDWORKS was whether or not the motor assembly could be removed from the frame after all of the tubes were welded in place. This for servicing purposes would be very important. We could see that it would easily come out of the frame without the exhaust system on, and that was our out. But until we actually tried it we didn't know if we could remove and install the entire engine assembly preassembled down through all of the tubes and in position.
As it turned out, by rotating and twisting in a very specific pattern, the whole assembly comes out of the frame relatively easily. Simply remove the 4 mounting bolts, and we were able to lift the motor out of the mounts.
After pulling the fuselage boom assembly and the motor from the frame we are now able to put the frame on the workbench and finish up all of the welding of the tubes. During the fitting process while the aircraft is assembled, we simply tack weld each of the tubes in place. But it is much easier to work with where we can rotate the frame into a comfortable position for welding. One of the great advantages of having a relatively small frame that is lightweight.
We can flip the frame into any position in order to make it easy to access the welds. The little "Mr. Tig" TIG welder is really handy for this kind of welding. The downside is the duty cycle is relatively small. The big syncro-wave 250 welder that we utilize has a cooling system in the torch head making it virtually unlimited duty cycle. But for the prototyping process like were doing here, the small welder is much more user-friendly.
Being able to rotate the frame for welding makes it much easier to access each one of the joints.
Welding motor mount tubes for the Polini Thor 250.
February 12, 2017
Well, first day of the year that we were able to open up the hangar and enjoy some of the sunshine. That lasted about 3 hours and then we realize that we been invaded by mosquitoes. Well, it was nice while it lasted.
We've been continuing to make progress on the Polini 250 installation. 1 of the 1st steps was to anchor the aft motor mount in position.
The motor mount plate allows us to screw the Lord mounts from the aft section and this very specifically orients the motor in all 3 axis.
In designing the installation we wanted to be able to use as many of the stock components that come with the Polini from the factory. In doing so we flipped the upper motor mount attachment bracket 180° and sent it to the aft bulkhead as its primary mounting location.
We had to machine a special bracket different from the stock mounting bracket. The reason for this is that the motor center axes is positioned 23° from vertical. And when the mounting bracket is flipped over it then repositions the existing bracket 46°. No problem, we simply had to manufacture a special bracket that would reorient the Lord mounts horizontally to be level with the rear bulkhead cross tube. The slot that is cut into the face is designed to engage the factory manufactured upper mount and prevent twisting.
Utilizing our tube template system we were able to get fairly close joints on all of the additional tubes.
The engine is now mounted into the aft fuselage. The actual tube count and weight of the new installation is just slightly less than the original aft mounted engine configuration.
Next step involves a few additional support tubes that will tie the forward and rear bulkhead's together.
February 11, 2017
This morning we start with a fresh slate. All of the reinforcement tubes for the rear bulkhead have been removed so that we can begin the process of installing the new tubes for the Polini 250 installation. Any time that we weld or grind away other pieces of metal on the frame we go through the process of applying a small thin coat of etching primer. The humidity during the winter months here is enough that we will see corrosion if we don't.
We are creating tube templates for all of the tubing components. If you haven't seen how we do this system it's really quite unique. Jason is the master of the tubing templates. He can grab a template and make up a tube that fits just about perfect every time.
After marking the tube we simply grind away all of the material that is left by the marking pen. We use a silver sharpie that is made for marking on metal and the silver color stands out really clearly against the darker colored 4130 steel tube.
We are having to manufacture a few new components for the motor mount system. This is the flat layout for the aft motor mount attachment. This will have to be bent later and then welded to the rear bulkhead motor mount tube.
These 2 tubes that are installed here will carry the majority of the load for the Polini 250 installation.
We were able to bring the new Tig welder from the main shop down to hangar 7. It is a 110 powered welder on a small welding cart which makes it very mobile. We normally use the big Miller Synchrowave 250 welder which is very versatile but not very mobile. Being able to weld in hangar 7 has been a great plus since the weather has been so miserable over the last couple weeks. The more that I use this little welder the more comfortable and confident I am in its abilities. For its cost it's probably the absolute perfect welder for building the EMG-6. We are planning to do some reviews on this welder but until I get some more time utilizing it and testing it in different applications we will hold off a a bit longer.
February 10, 2017For the last couple weeks we been working on the SOLIDWORKS drawings for the Polini 250 installation. We're getting pretty close to the final installation mockup in CAD. We are still waiting on several of the design components to show up so that we can continue the design work. We really can't start the installation until we have completed the entire design and the fitting of all of the individual assessor ease like the radiator, fuel tank, header tank, intake silencer, battery, fuel pump, starter relay etc. all of these components need to interact and fit cleanly into the installation and sometimes even having one component 1/4 inch at a place screws up everything else.
February 9, 2017
We have several projects that we been finishing up on with SOLIDWORKS in preparation for some modifications to the aircraft. We brought fuselage frame # 3 down to hangar 7 to start work on the Polini installation into the rear fuselage. Although we've conducted quite a bit of test work with the engine mounted on the aft bulkhead. All of that work that we conducted was simply for test purposes to validate the viability of the Polini 250. By mounting the engine in the rear of the fuselage we will be able to significantly reduce the amount of drag and should really improve the performance and the aesthetics of the aircraft.
We started pulling accessories off of the Polini so that we could hang it in the proper location and start visualizing the different options for the mounting and routing of the accessories, exhaust, drive system, fuel system, etc.
In order to start with a "fresh slate" we decided just to go ahead and remove some of the tubes that were going to interfere with the installation process. That's 1 of the great things about having a 4130 chromoly steel fuselage frame. The ability to make modifications is relatively simple. We've done so much of this were not afraid to just hack into the tubing and make repairs or modifications. The initial drawings on SOLIDWORKS showed that these tubes are going to be redundant anyway after we make the modifications for the Polini mount system.
We got several other projects in works right now that require the fuselage frame to go together for some additional testing. In preparation for the wing load testing that we are gearing up for we will need the fuselage frame and boom assembly completely assembled.
We had forgotten that we had previously mounted the fuselage boom so it took about 5 minutes to bolted back onto the fuselage frame. We'd intended to bring it down and do a video of the mating process. I guess we'll just have to make a another fuselage frame and fuselage boom to make that video. No problem.
February 8, 2017We just hit 1000 subscribers thanks to all of you that follow this webpage and the YouTube channel.
|Were still not sure exactly what we have achieved in terms of additional benefits from YouTube. We are hoping that we will be able to get some additional access to customer support. Being able to talk directly with someone at Google or YouTube has been impossible. This is the email that the sent after reaching the 1000 mark.|
YOU JUST UNLOCKED OPAL BENEFITS!
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February 7, 2017We have been diligently seeking out some additional options for electric power systems.
We have been in contact with Steve Tice from EV Drive
EVDrive web-site -> http://EVDrive.com
Steve recommended a series of batteries from lunacycle, check out the link below.
We've also been in contact with John from electric motor sports.com looking at the PMAC 15 kW continuous power motor drive system.
We are still reviewing this systems capabilities to determine whether or not it would be adequate for the EMG-6. They are willing to work with us to develop a package that is specifically designed for the EMG-6. And we are looking at the integration of the other modular components into the aircraft.
Click on the link below to see more information about this motor.
February 6, 2017
We received a phone call and an email this afternoon. We are all pretty excited.
Congratulations, you have been selected as the 2017 General Aviation Technician of the Year. I will contact you again later with more information about the awards ceremony but for right now; celebrate!
General Aviation Awards Committee
Carol has become pretty concerned that my head might swell up as a result of this new award. She vows to do a regular check to ensure that it's not growing.
February 4, 2017
New battery technology. Check out the link below.