Internal Antenna Mountings On Fiberglass Belly J-Model

[Controller92]

I am doing the Single Piece Belly Panel modification on my ‘77 J model and I have heard that the antennas can be mounted internally to get them out of the airstream. Does anybody have any information on doing that part of the modification? I am trying to drum up some information for the IA doing the modifications. 

[KSMooniac]

Transponder, marker beacon, ADS-B in, etc are candidates. Just be cognizant of ground plane requirements.

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[kortopates]

I am doing the Single Piece Belly Panel modification on my ‘77 J model and I have heard that the antennas can be mounted internally to get them out of the airstream. Does anybody have any information on doing that part of the modification? I am trying to drum up some information for the IA doing the modifications. 

The popular antenna to put in the belly pan area was the marker beacon antenna done in all the modern Mooney's. But these days there is virtually no need for one so hard to justify the trouble and expense.
Vertically polarized COM Antenna's should be on top of the plane. Horizontally polarized NAV antenna's would be best placed in the wing tips to hide them where they have a better view for VOR/LOC/GS signals rather than belly.  My NAV antenna's are one in each wing tip. 

[David Lloyd]

I had a Stormscope antenna located inside the belly.  About all it saw was cycling the gear and flaps.  Does a lot better now located in fresh air.

I would not attempt to put a transponder antenna in the belly unless a radio shop proved to me that it would work properly and meet the legal specs.

[larryb]

I removed the marker beacon antenna and installed the 2nd ADSB in antenna in its place. It works very well.

[A64Pilot]

The flat plate drag area of an Xponder / ADSB antenna is pretty darn close to zero.

[larryb]

I actually didn't do it for drag. My belly pan has two pre-drilled mounting pads for flat blade transponder/dme antennas, Left and Right. The Right mount is where the transponder antenna was mounted and is also right behind the exhaust. The antenna took a lot of heat and was warped and cracked. I had that antenna replaced and moved to the Left position, away from the exhaust. Due to the exhaust, I view the Right location as un-usable. When it became time to install an antenna for my GDL52-R, I went for a rod antenna behind the belly pan in the marker beacon location. And it works great there. It's also one less cable requiring attaching when the belly panel is removed.

[geoffb]

On 11/6/2022 at 12:45 PM, kortopates said:

The popular antenna to put in the belly pan area was the marker beacon antenna done in all the modern Mooney's. But these days there is virtually no need for one so hard to justify the trouble and expense.
Vertically polarized COM Antenna's should be on top of the plane. Horizontally polarized NAV antenna's would be best placed in the wing tips to hide them where they have a better view for VOR/LOC/GS signals rather than belly.  My NAV antenna's are one in each wing tip. 

Paul,

I'd been meaning to ask.  In an earlier thread you'd mentioned using the Laser wingtip STC to support the install of wingtip nav antennae.  Do I recall that correctly?  And if so, it's the Archer ones?

 

[KSMooniac]

Archer antennas are the ones designed to fit in a fiberglass wingtip.  Depending on your shop/IA, installing them could be a minor mod.

[kortopates]

1 hour ago, geoffb said:

Paul,

I'd been meaning to ask.  In an earlier thread you'd mentioned using the Laser wingtip STC to support the install of wingtip nav antennae.  Do I recall that correctly?  And if so, it's the Archer ones?

 

STC was needed only to install the Bob Archer Nav antennas - since they're not approved. If you have the room you could install approved antenna's, such a Comat blade antenna as I previously had. But I had to go to lower profile antenna when I did the Encore upgrade with double the size control weights. You'll have the smaller size weights with room to give you options.