The last thing I want is for this assembly to get ripped off of the leading edge of the wing during moderate G maneuvers of say 4 Gs or less, so I need to make certain that my "in wing" concept is sound. There are risks of fire nad potential structural failure of the wing at stake here, so again, consider this my disclaimer that if you wish to take on thise sort of thing yourself, you need to do the research, consider the risks, and take the appropriate steps to properly design and test leyour ideas. The EAA and the FAA are gracious enough to allow us to experiment with our designs, and provides several programs that we as builders can take full advantage of to ensure that we are doing so as safely as possible.
After a bunch of rough sketches, notes, and hours of deep thought about how best to design and build the gun farings, I came up with the basis for a prototype design. I plan to use a special reinforced fiberglass material, polystyrene foam, and a combination of various filler and strengthening materials to reinforce the critical areas of the faring that attaches the assembly to the wing. This, combined with some stock and fabricated PVC parts from the local HD aviation supply store, will make up the bulk of the materials.
So here are some more pics:
First is the fabricated gun fairing assembly that houses the bulb base as well as the light bulb.
I tried very hard to find an existing PVC part that had the base flange that I needed, but I can tell you with reasonable assurance that it does not exist. There are parts that I found that are close, but they are designed for much larger electrical and plumbing assemblies with diameters of 3 inches or more, and are much too large for my application, not to mention very expensive. So I had to come up with a way to fabricate my own flange. I settled on a conduit junction box that has walls that are 1/4 inch thick. All of the parts are rough cut only, and are not perfectly symmetrical. Part of the prototyping process involves figuring out the required assembly steps, and I am not after perfectly formed parts at this stage - just enough to get the basic design down.
I used a piece of .032 alclad aluminum from a trim kits I purchased long ago from Vans as a backer plate for the assembly. What you don't see is yet another aluminum plate that I will probably add to the front before it is all done. I thought that I could simply countersink the PVC for the #6 countersunk screws I plan to use, and just encase that in Epoxy and fiberglass for added strength. What I have found is that the PVC I am working with does not counterink very well using manual methods, and it also caused me to question the strength of the PVC. So as a result I will sandwich the PVC flange between two pieces of aluminum and then encase it in fiberglass. This way I can dimple the aluminum on the front for the #6 screws so that they have a solid mounting patform.
Here are the pieces left over from the PVC junction box after cutting some circles on my band saw:
From the rear you will notice that I am using a special nut plate designed to fit in tight corners. This seems to work well and I just need to iron out my match drilling process to ensure that all holes for assembled parts are properly aligned. The whole concept behind this assembly is to make it removeable so that the electrical wires and the light mounting base can be connected/disconnected, inspected, serviced, or replaced as needed. This entire assembly will be mounted to the rest of the fabricated gun port faring on the wing.
I will close this post with a couple of vidoes that prove that this design will work. The first video I got all the way up to connecting the circuit, and of course it did not work! I am having some strange problems with the strobe controller from time to time, but until I have a stable, mounted electrical platform to work with that is on a continuous source of 12 volt power instead of a 9 volt battery, it is hard to say what is causing the problems. IN one case the strobe controller became horribly confused and would not even shut off. I will have a series of switches in the airplane that will control power supplied to the light system, so I don't think I will have any problems shutting it all off whenever I need to, but it is a bit disconcerting to know that the the system may very well develop a mind of its own.
EDITED 5-26-17. The above video only shows my test setup. The lights would not energize for any of the reasons listed in the next paragraph. I ended up tweaking some things (don't remember if it was a new battery or if I discovered some play in the connection between the back plate and the grounding tabs of the light socket, but in the next post at https://bryansrv8project.blogspot.com/2013/04/fooled-ya.html I finally got it working.
ORIGINAL Entry.....See edits above and go to the next post to see it working.
And here is the subsequent video where I managed to get it to come to life. Again, not sure why it decided not to work the first time, but it may have something to do with the forward voltage requirement for such a high powered LED, and the use of a less than fully charged 9 volt battery for testing, or a short in the wires, or a fault in the chip circuitry of the strobe controller, or the alclad coating not providing a good electrical contact, or..... well..... you get the idea. Lots more testing needed on all this.
And finally, if you think what I am doing is kinda cool, I have been sitting here watching an episode on the Smithsonian channel called the incredible flying cars. It is absolutely amazing to see the level and type of technology that is currently being developed and tested in today's world. While I am certainly no engineer in the typical sense, I am still absolutely amazed at what the collective imagination of all those engineers can conjur up.
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