Fuselage page 26-10 - Two 11/16" holes in bottom skins

[bertschb]

The plans on page 26-10 call for drilling two 11/16" holes in the bottom skins of the fuselage (one on each side). But, like the call out for drilling a large hole in the bottom of the aft fuselage, they don't mention what these holes are used for (at least not on page 26-10). In the case of the large hole in the aft fuselage, I learned that hole is used for an ADSB antenna which I don't need because I'm using a Garmin GNX-375 which I understand uses the GA-35 antenna which includes both GPS and ADSB. I think.

Before I drill two more large holes in the bottom skins that I don't need, does anybody know what these two holes in the mid fuselage are used for? I'm assuming it's for antennas but if so, how does Vans know which antennas people use or where they want them installed (or how big the holes should be)? Sorry for the stupid question but I'm a clueless new builder.

I've purchased two antennas from Stein. The Comant CI-122 COM antenna and a Garmin GA-35 GPS antenna. I don't plan to navigate using VOR so no VOR antenna. I figured the COM antenna would go on the bottom of the fuselage and the GPS antenna on top somewhere. I also assumed I'd be mounting these antennas later in the build when I'm doing the avionics.

If these two holes are used for antennas, it seems to me the plans should say - "If you plan to mount a COM antenna on the bottom of the fuselage, drill an 11/16" hole here. If you plan to mount a VOR antenna, drill an 11/16" hole here."

 

[georgemohr]

Are these the holes very close to the square main gear leg openings (RV-14A)? If so, these are to permit the brake line fitting to extend outside the fuselage bottom.

 

[bertschb]

Are these the holes very close to the square main gear leg openings (RV-14A)? If so, these are to permit the brake line fitting to extend outside the fuselage bottom.

Dang! I forgot to attach a screen shot of the page I was referring to (it's included in my original post now). Yes, the two 11/16" holes are supposed to be drilled just in front of the two rectangles we are asked to cut out for the tri-gear planes. If those are for brake lines, that makes sense!

I was hung up on the antenna hole I was supposed to drill in the aft fuselage thinking these were more antenna holes. I lost sight of the location of the holes being so close to the openings for the gear legs. No way they could be for antennas. Sheesh! I'm such a rookie....

 

[stigaro]

Yep, brake lines go in those holes, attached to the gear leg brackets. If you're doing the -14A, you'll want those. The other holes in the belly, I agree, try to determine ahead of time if you need them. One is for the transponder antenna, which may or may not be required depending on what you are planning. The other ones to note are the COM antennas. The plans are specific to the 2 hole Delta Pop antennas. The Comant antenna mounts using the 4 corners instead of the two inline studs. And I believe the belly skin is set up for 2 COM anntennas, so be aware if you only plan to mount 1.

 

[bertschb]

...The other ones to note are the COM antennas. The plans are specific to the 2 hole Delta Pop antennas. The Comant antenna mounts using the 4 corners instead of the two inline studs. And I believe the belly skin is set up for 2 COM antennas, so be aware if you only plan to mount 1.

Thank you! This is very helpful.

 

[HAL Pilot]

The antenna holes are forward of the spar. I believe those holes you are referring to are brake lines for the tri-gear A model

 

[Tdeman]

Sounds like others have got you sorted on the intentions of holes.

One thing I'll clarify, is that while the GNX375 receives its GPS positional data from the GA35, it will additionally require a transponder/ads-b antenna. Cool note on the GNX375 is it uses the same antenna for ADS-B in and transponder/ADS-B Out. So you'll still need to stick a rod or blade somewhere!

 

[stigaro]

Sounds like others have got you sorted on the intentions of holes.

One thing I'll clarify, is that while the GNX375 receives its GPS positional data from the GA35, it will additionally require a transponder/ads-b antenna. Cool note on the GNX375 is it uses the same antenna for ADS-B in and transponder/ADS-B Out. So you'll still need to stick a rod or blade somewhere!

I've been wondering about this actually. Good to know it uses the same antenna for both functions.

 

[bertschb]

One thing I'll clarify, is that while the GNX375 receives its GPS positional data from the GA35, it will additionally require a transponder/ads-b antenna. Cool note on the GNX375 is it uses the same antenna for ADS-B in and transponder/ADS-B Out. So you'll still need to stick a rod or blade somewhere!

Thank you for this. I went back and looked at my Stein receipt (again) and saw that I also purchased the Comant CI-105 transponder/ADSB antenna for use with the GNX-375. I think it's this CI-105 combo antenna that makes the aft fuselage ADSB antenna redundant which is why I didn't need that aft fuselage ADSB antenna hole.

 

[HAL Pilot]