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Bolivia 4-Place Build

Maybe it is going on and off again so no big deal yet but you asked if we see anything - cotter pin is missing stabilizer yoke nut. Also fwiw Piper flips that bolt around and puts the nuts on the outside (I suspect so you can see them on preflight).

View attachment 63311
ELT antenna installed.[/ATTACH]

If anyone sees something done wrong give me a head up please.
 
Here is my ground plane out of .016" aluminum. Tabs welded to the diagonal tube that the antenna attaches to.

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Here is my ground plane out of .016" aluminum. Tabs welded to the diagonal tube that the antenna attaches to.

View attachment 63320

OK. For the rest of us; this is how this type of antenna should be placed on a ground plane. An ideal shape for a ground plane is round. The reason for this is that the ground plane is a part of the antenna system. Without one, the antenna will have, at best, a point blank range. With a correct ground plane, the antenna will transmit equally in all directions. I.e., if you install an antenna on a long skinny ground plane, the best transmit range will be in the direction of the long axis of the piece. As installed in post #35, the best range will only occur to the left/left rear of that aircraft. Although round is best, in a small rag aircraft, we reach for the best we can. The ground plane in Mr Pierce's pic shows a good compromise. Plenty of square inches of ground plane even if it's not round shaped, and antenna attached directly to it. If I changed it at all it would be to move the antenna forward to more closely center it on the ground plane.

Web
 
Here's what I did on the Exp I'm working on.

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Maybe it is going on and off again so no big deal yet but you asked if we see anything - cotter pin is missing stabilizer yoke nut. Also fwiw Piper flips that bolt around and puts the nuts on the outside (I suspect so you can see them on preflight).
Thanks. Proper hardware in now.20221026_103129.jpeg

Sent from my SM-G965U1 using SuperCub.Org mobile app
 

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Windshield looks like it will fit
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Jonathan has been the boot cowl expert. Looking good, nutplates installed.

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Question: I want to use this same arrangement for the parking brakes. The Scott parking brakes I have are set up with a Male 1/8" pipe thread where they used to screw into the Scott masters. Is there a way to convert to female pipe thread with a AN822 elbow like this picture

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Sent from my SM-G965U1 using SuperCub.Org mobile app
 

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Understood - For that reason I had a couple conversations with the manufacturer re signal shielding, including sending them pics. They said it is fine. I felt like this location is better protected from crash damage. Thanks -
 
The main difference between yours and Mr. Pierce' is, his antenna is above the ferrous metal tubing. Your appears to have tubes above, below, and to both sides.

You do what you're going to do. You're the one flying that thing. I just want to make sure the BEST info is there to be considered. As I said above, there is no such thing as 'good enough' with safety equipment. Do you want your last conscious thought to be 'Man, I hope that thing works'?

Web
 
Thanks for your input. My biggest concern is one I don't know how to address, and is one that would apply at least equally, if not more, to Steve's installation. That is if the plane is upside down, the antenna's ground plane is between antenna and satellite. Also, in Steve's installation there is more metal between antenna and sky if upside down. Can you shed light on how that would work? I'm ignorant on that.

I realize that the extent of Faraday screening depends on the size of apertures in comparison to wavelength, and that it becomes more significant when aperture size is significantly smaller than wavelength (~74 cm for 406 MHz).

(FWIW on my certified plane the antenna is an external whip on top of the fuselage. It's ideal when right side up, but subject to damage and increased Faraday screening if upside down.)
 
The following is from the manufacturer's installation instructions, pg 42. https://www.eltechnolgies.com/_files/ugd/38ad3c_61a13e5c43ac42a1bc9ea9eb6120f910.pdf
One method is to install the antenna inside the fuselage. The signal will radiate through thefabric. It is important, however, to choose the location carefully. The samerestrictions, not shadowing or masking the signal by metal obstructions, still apply. Aircraftstructures such as tubing or ribs do not generally constitute an obstruction. The ground plane must be grounded to the aircraft ground.
 
Do you want your last conscious thought to be 'Man, I hope that thing works'?

Given the rather low rate of ELT activation in crashes that does seem like a valid concern regardless of how good the antenna installation is.

For what it's worth - CubCrafters ELT antenna on the FX-3 is totally enclosed by fuselage frame and fabric. They claim to have performed a sucessful COSPAS/SARSAT test with that installation.

It may be interesting to compare radiated signal strength for antenna outside fuselage and inside fuselage with the same ground plane. Not technically difficult to do but would take a while to get enough points to construct a good polar plot.
 
In times of old when 406's weren't sold we had portable 121.5 ELT's. Most were cockpit mounted. If needed they could be quickly removed and used outside the aircraft. Now there's some ELT's that are pretty much hard mounted in places that are not readily accessible. Plus they may not have a separate antenna that could be attached when removed if the main one or coaxial cabling is compromised from damage or fire. It might be time to rethink how we would ensure the ELT functions as expected.

Gary
 
It may be interesting to compare radiated signal strength for antenna outside fuselage and inside fuselage with the same ground plane. Not technically difficult to do but would take a while to get enough points to construct a good polar plot.

Agreed.

I've mapped out radiation patterns with coms and they are rarely symmetrical. There always seem to be lobes at certain clock positions around the antenna.

I can imagine a test run for FAA eyes. The incentive to accept the first (only?) positive results would be immense.

Web
 
In times of old when 406's weren't sold we had portable 121.5 ELT's. Most were cockpit mounted. If needed they could be quickly removed and used outside the aircraft. Now there's some ELT's that are pretty much hard mounted in places that are not readily accessible. Plus they may not have a separate antenna that could be attached when removed if the main one or coaxial cabling is compromised from damage or fire. It might be time to rethink how we would ensure the ELT functions as expected.

Gary

Disagree only slightly. Even the new 406's can be made portable with a little thinking involved. There are portable antennas that will physically fit almost any ELT. And they work well, even if the ELT manufacturer claims that the ELT is only 'legal' with their antenna. Any antenna will function correctly IF; it is made for the specific frequency band (in this case, it needs to be made for 406 mhz and 121.5 mhz) and it connects to the ELT with a matching connector.
The other thing to remember is some brands, like Artex, have a jumper wire inside the ELT wire harness connector. If you remove this jumper, the ELT will NEVER activate no matter conditions or switch position. If you pull one of these from a wreck, cut the wire harness , leaving a few inches of wire hanging on the connector on the front of the ELT, and it will still activate/function.

Web
 
Aircraft Spruce and likely others sell portable ELT antennas. Typically they have a female BNC connector and can be used on 121.5 and 406 Mhz. Some ELT's may require different antennas/connectors. I'm suggesting the owner/operator familiarize themselves with potential portable operation before the event.

Gary
 
My opinion for what it is worth. I am not convinced the square tip wing, or extended wing, actually makes a difference. To the best of my knowledge no one has ever done a comparison. The whole reason I had those wings is that I intended to try to do a comparison evaluation. The problem is no one (to my knowledge) has changed out ONLY the wings (ie one variable) and done a serious flight test evaluation. The same airframe has never had both sets of wings. In every case an airplane is built, then the owner/builder lauds the performance of the square tip wing with no true comparative data. He is comparing it to a completely different airplane.
The only way to find out if there is a performance difference is to fly the exact airframe with both sets of wings, controlling the variables as much as possible, and doing a controlled flight test. Not just flying it around and saying "it flies better".
I do not know which wing is better and frankly I do not believe anyone else does either. It is just another Alaska "old wives tale" until properly tested.

My opinion only

Bill

Bill,

I flew a Super Cub with extended wings and droop tips, stock flaps and ailerons for several years at work. Floats much of the year, wheels the rest. Ran engine past tbo, and plane received a factory reman O-320. The next year, Maintenance had me bring it to ANC for recover in fall. Management wanted to get rid of the extended wings, and I didn’t argue, so a new set of wings were installed on the plane. To the best of my recollection, nothing else was done to the plane during recover. This was a 1969 plane, bought new by FWS and never wrecked.

I flew that plane, with stock wings, for about another year, mostly on floats.

There were two notable differences in that aircraft: First, it took a notably longer distance to get off the water, when heavy. The lake I operated off was narrow, so easy to see difference. No scientific tests done, but takeoff distance increased by over 100 feet, at least, and maybe more. Second, the airplane, with extended wings and original aileron location had very poor roll authority. I flew that thing in a lot of turbulence, and after a while, you realized the stick didn’t do much. With stock wings, roll authority was much better, very noticeable.

About the same time, a friend had his SC rebuilt, also on floats. His wings were extended, but ailerons were moved to the tips, and flaps extended. It too had an O-320. I flew that plane some, and it performed on takeoff very close to the plane I flew when it had long wings. But, and this was a big but, it had roll control. I was wishing we’d kept the long wings and done the aileron/flap mods.

Im not a test pilot, by any stretch of the imagination, but I flew that plane, day to day, working it, in all sorts of loads and missions, with a lot of low level maneuvering flight. I much preferred flying the stock wing to the long wings, with stock ailerons, even though takeoff performance clearly suffered. At the time, we were operating these aircraft as “Public Aircraft”, and our outfit “suggested” using 2050 GW. In fact, we operated some heavier than that.

I never did a comparison of takeoff distances on wheels, but I don’t think the long wings really helped performance much on wheels. Roll authority still sucked, though.

Floatplane performance really benefits from two things: wing and thrust. Talk to anyone who’s flying a Skywagon with Wing X on floats.

Again, totally unscientific observations….take them for what they’re worth.

MTV
 
On the subject of ELTs: I installed a 406 from ACK some years ago. The G-Switch failed in the transmit mode, no accident required. I disconnected the ELT from its external antenna, and left it lying in the baggage compartment of my Cessna 170 while I went to find tools to remove the battery. The nice Major from RCC called (again) to remind me that my ELT was still transmitting. I responded with its condition and location. His response: “No matter, we’re still receiving its signal, including its GPS location. ELT was connected to portable GPS when it first activated.

So, successfully emitting through an aluminum structure.

Your mileage may vary.

It is salient to understand that the 406 signal goes out at a MUCH higher power than 121.5 signal did. The 406 is a pulse every 50 seconds (I think), so, while more power output, it doesn’t use as much battery as 121.5 did, transmitting at much lower, but continuous power out.

MTV
 
Web- I think the jumper on the Artex is only to enable the g-switch. The elt can still be turned on manually.
 

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I've 'made contact' from a bench in a hanger. I still wouldn't depend on that setup if I was bleeding.

The Artex ELT 345 manual says one 5 watt pulse every 50 seconds. But don't forget that the 121.5 signal is still continuous out.

Web
 
Web- I think the jumper on the Artex is only to enable the g-switch. The elt can still be turned on manually.

You're right. It's a change from the older ones. Not a bad change though at least when we consider using it as a portable. The next time I have a 345 on the test rig, I'll verify that.

Web
 
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I've 'made contact' from a bench in a hanger. I still wouldn't depend on that setup if I was bleeding.

The Artex ELT 345 manual says one 5 watt pulse every 50 seconds. But don't forget that the 121.5 signal is still continuous out.

Web

Correct, at much lower power out….250 milliwatt??

MTV
 
A whopping 50 mw. Lol

But it's only for the last part of the search. For the guys on the ground, in the brush looking for the wreckage. In good terrain maybe less than a mile range?

Web
 

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The options are pretty limited. I should have cut off the sump tabs and welded them lower. In 3 point it really isn't too bad. I'll try to get a better picture
 
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