PIPER J5.5
FRIEND
corvallis,or
Im speechless about the location of this antenna. I really am.
Where to fit the Mode S Transponder Antenna
- Thread starter Philly5G
- Start date
Brill!!! Another thing learned!! Thanks Web!! I’m thinking about zip tying the coax to the middle tubes, behind the parking brake cables and feeding through that way, but I’ll report back with what actually happens!!
Does the false boot easily come away when the front and side screws are removed? I’m assuming it’s not attached to the gear doors?
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wireweinie
FOUNDER
Palmer, AK
The false boot is just a wrap around piece of sheet metal. It's a matter of removing the correct screws. Each installation can vary a little as owners and mechanics install more/less screws and in different order. Look it over and see what you have. You only need to have enough room to reach a hand inside the lower boot cowl area.
Web
Web
spinner2
MEMBER
Montana
It is a simple matter of access and ground plane. This is the third location for a transponder antenna on this plane; a CC EX. The CC has a large triangular aluminum belly pan and I had a TED type antenna here to start with. But a belly pod addition had me move it to the boot cowl. On the CC the boot cowl is different than an -18 and there was just one place suitable for the TED. CC came out with a fuel drain SB that I took my time complying with. IMO it was a solution looking for a problem but I bought the kit and installed it. But doing so prevented the boot cowl TED from staying where it was.
At at the same time I installed a GDL 82 for an Out solution. Where to put the blade antenna? I considered the tail clean out pan, like Kirby’s. But I decided against that because of possible damage on skis. I talked to my avionics shop and they advised under the wing, saying they’d done that on some seaplanes and flying boats. I had access to run coax through the nose ribs with the landing light removed and the leading edge skin works well as a ground plane. I get uninterrupted ADSB uplinks so it isn’t a shadowing problem. It also isn’t much different in location than the new wing tip light replacement Out solutions on the market now.
Hi Web, I’ve got the boot cowl loosened and the multiple years of crud vacuumed out!!! Removing the false boot was the real key and on looking forward through it, I felt like Mr Carter at his first glimpse into Tutankhamen’s tomb!!!
There’s also loads of height clearance for the coax!!!
Question, my 12 has ridges on each side of the horizontal bottom of the boot cowl which is kind of recessed between them, will these affect the antenna AND will the less than vertical line-up of the antenna also affect performance?
Also, general question, should the gear doors be the shape they are, or a flatter, more continuous and pleasing bend?
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wireweinie
FOUNDER
Palmer, AK
Hopefully you survive the curse better than Carter's crew!
That recess may be less than ideal but I'd say it will work just fine. If I was installing this antenna for you, I'd keep it close to center, left/right, and roughly six inches from the rear edge of the boot cowl. And if the antenna is within 10 or 15 degrees of vertical, in level flight, it will function correctly. Remember that while vertical is perfect, it's made to work as the aircraft maneuvers.
Those cover panels look like they've been worked over pretty hard during maintenance. You could fabricate replacements fairly easily.
Web
That recess may be less than ideal but I'd say it will work just fine. If I was installing this antenna for you, I'd keep it close to center, left/right, and roughly six inches from the rear edge of the boot cowl. And if the antenna is within 10 or 15 degrees of vertical, in level flight, it will function correctly. Remember that while vertical is perfect, it's made to work as the aircraft maneuvers.
Those cover panels look like they've been worked over pretty hard during maintenance. You could fabricate replacements fairly easily.
Web
hotrod180
FRIEND
Port Townsend, WA
Is that speechless pro or speechless con?
Although it might be in some danger of walkaround head strikes,
personally I think it's a good example of thinking outside the box.
Kinda like Uavionix with their position light ADSB's.
Brill, thanks Web!! No sign of sudden and grisly end of life experiences as yet, so fingers crossed on the curse of the boot cowl
I was thinking of putting the antenna towards the back as the indent is less there, as you can see in this pic, so thank you for the confirmation! I was slightly worried it would be nearer the gear legs, but sounds like they don’t usually interfere.
I thought the cover panels looked pretty beaten up, so I’ll take them fully off and either straighten them, or think about replacing them
BTW I’m sure other people will have done a similar idea, but I racked my brain to get a comfortable/bearable working position when fitting the transponder and radio mounting panels to the front tubes with P Clips and came up with this:
I took out the front seat (again!!) unbolted and lay the front stick on the floor and rested these boards on the seat mounts with steadying supports front and rear. Sat on the boards facing backwards and basically scrunched under the panel, lying on the boards and did the previously nightmarish fumbling around, in comfort, lying down with a perfect view of what I was doing
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Ha ha ha!! Brilliant!!! Glad to have reminded you of one of the many plus points of your plane!!!!
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We put the gear doors through the metal bending rollers to give a nice continuous bend, after giving them a thorough clean and I covered the main pain chipped areas with orange vinyl. They now fit and look a lot better, although fitting the inboard hanger nuts and bolts was a nightmare!!!!
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Test flew the transponder today and got an AOK from ATC [emoji41] Thanks to all for the feedback and advice!!
@Web I fitted the aerial just where you said and even at 1700’ AGL and 20 miles from the airport, everything worked 100% to specification and tolerance
TOP advice!! THANK YOU!!!I also put some self adhesive O section seal between the gear doors and false boot to dissuade the oil from creeping in there
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Why do you need the 2 antennae? Is 1 not enough with this transponder?
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wireweinie
FOUNDER
Palmer, AK
Test flew the transponder today and got an AOK from ATC [emoji41] Thanks to all for the feedback and advice!!
@Web I fitted the aerial just where you said and even at 1700’ AGL and 20 miles from the airport, everything worked 100% to specification and tolerance
I also put some self adhesive O section seal between the gear doors and false boot to dissuade the oil from creeping in there
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Glad to hear that. Congratulations on a good install!
Web
Thanks!! Let’s call it a successful team install mate
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