At this phase of the project my attention is being divided between a number of different tasks which has the unfortunate effect of making the progress seems slower than it actually is. Many of these tasks are fairly trivial and don't seem to warrant a separate blog post. Nevertheless, if I don't post regularly, my reader assumes the worst. I assure you, dear reader, that the project is in fact progressing nicely.
That being said, I did incur a 5 day delay to my project when I recently traveled to Southern California hunting the elusive Gorn. Those acquainted with Star Trek will understand what a problem the Gorn can be, and may well recognize the landscape where this epic duel took place.
Alas, I didn't spot any Gorn but it was fun to look. By the way, the location should look familiar as it has been used in literally hundreds of movies and TV shows. Vasquez Rocks is just east of Santa Clarita CA.
This posting concerns the ELT (Emergency Locator Transmitter). There are currently two types of ELTs used in civilian aircraft. They are specified by the frequency on which they transmit. 121.5MHz and 406MHz. 121.5 is the old frequency that is now being phased out. The newer frequency is the 406MHz model. My ELT has the capability to transmit on both, but at some point in the future no one will be listening to the 121.5MHz frequency.
The 406MHz ELT signal in addition to being a beacon that can be radio located, also carries GPS information which is relayed via satellite to the would be rescuers giving them an exact location.
The ELT must be mounted within the aircraft in a specific orientation so that the radio is automatically activated in the event of a crash. There are several suitable locations, each having its own unique challenges. In the end, I selected a location in the tailcone. In the photo below, the ELT is the orange box. Below that is the mounting plate that it comes with. To the right are the pieces of scrap aluminum that I collected to build a strong attachment to the aircraft.
So the basic idea is to mount the supplied plate to the J-stringers inside the tail cone just behind the rear baggage compartment bulkhead. A couple to circles are cut out to lighten the mounting a bit. On the forward and aft edges I've riveted on some light weight stiffeners.
And here is the ELT in place. This location is considered fairly survivable due to the proximity of major structural components. Principally, the J-stringers and aft baggage bulkhead.
The ELT's whip antenna is located under the rear canopy, just behind the roll bar. Its not the best location for the antenna being so close to the roll bar, but it is fairly close to the ELT itself and the antenna should have a fairly unobstructed view of the sky through the canopy. One problem to solve with this location was how to keep the metal antenna from touching the metal roll bar. In addition, the whip antenna needs to bend over a bit to keep it from contacting the canopy. My solution is a nylon standoff with a slot cut into the side to restrain the antenna. The standoffs are held in place with nylon 8-32 screws driven in to the back side of the roll bar and retained using a self-clinching 8-32 nut.
Here's the top half of the ELT antenna. Bonus: In the background the interior side panel is being test fit.
Next time I move on to the canopy frame.
No comments:
Post a Comment