Archer Com antenna in RV-10 Wingtip?

czechsix · #1 10-05-2017, 05:21 PM

Has anyone tried a Bob Archer VHF Com antenna in the RV-10 wingtip? PIREP? Pictures?

I'm building a -14 but it has the same wingtip as the -10. I'll have dual Coms, and plan to use a belly-mounted bent whip for the primary Com. I'm thinking about the wingtip location to reduce drag for the second Com. I already know the wingtip Com antenna won't perform as well as an external antenna, and there have been mixed reviews from people who have installed them in the 2-seat RVs. Some people found them unacceptable, others seemed satisfied that the performance was good enough for a second radio used primarily for a backup.

The -10 and -14 have a substantially thicker airfoil than the rest of the RV series, so I'm wondering if perhaps the wingtip antenna may do a bit better due to the greater vertical polarization potential, but I could not find any antenna performance reports specific to the -10 in the forums...

Actually there is one thread (found with Google instead of the VAF search engine): http://www.vansairforce.com/communit...d.php?t=107189

Any others who have tried this antenna?

Thanks,

Walt · #2 10-05-2017, 07:05 PM

Do yourself a favor an forget this idea.

vic syracuse · #3 10-06-2017, 05:34 AM

The 10 is a really nice cross-country traveling machine, and because of that you will most likely fly in the weather once in a while, at least we do. I don't fly in any serious weather, but it is nice to have the capability to get up and down through layers or perform an instrument approach or instrument departure when needed. There is nothing worse than not being able to hear ATC when you are in the thick of it. The drag of an external antenna is minuscule and far is far outweighed by the increased clarity and range in communications.
I know you are thinking that you are planning on one external com antenna. Keep in mind that radios do fail.

Vic

scard · #4 10-06-2017, 06:02 AM

Listen to Walt and Vic. I had one in a wingtip that didn't make it out of phase I over 10yrs ago. It was quickly moved to a "proper" external location.

bruceflys · #5 10-06-2017, 06:16 AM

A belly com antenna is sometimes insufficient to reach ground control. If your wingtip com antenna's line-of-sight to the tower is also blocked by the fuselage, you have a problem. A whip antenna for com #2 on the top of the tailcone takes care of both issues.

Jesse · #6 10-06-2017, 06:30 AM

We tried an Archer COM antenna in our first RV-10 and were so disappointed with the performance that we removed it and put another bent ship on the belly. The wingtip Nav Antenna, on the other hand, we have always been happy with.

Carl Froehlich · #7 10-06-2017, 07:39 AM

I've posted on this before.

My first RV-8A I made a wingtip comm antenna. Flying with someone that had the Archer antenna I had to really coms to ATC as they could not hear my buddy.

Wingtip antennas (bought or made) work only as a well as they are installed and tuned. If you do not have an antenna analyzer like this don't even try: https://www.gigaparts.com/mfj-259c.h...SABEgKXzvD_BwE

Two things:
- Page 13-16 of the Aero Electric Connection provides the basic wingtip antenna design. Use that to figure out how best to extend out into the full width of your wingtip - and with the most change in vertical placement. Note the first third of the antenna does most of the work, so this is what you want to be as vertical as possible. The tail that runs aft along the outer edge of the wingtip brings the antenna into resonance but does little of the actual work.
- Make the tail a little long so that you can trim it to resonance. Remember the tail length will determine resonant frequency, the Gamma Match (the little stub with an insulator where you attach the feed line) does the impedance matching to your 50 ohm coax.

This antenna will never work as well as a properly installed belly whip - but does just fine for the backup radio. This is also the only VOR antenna I would ever consider putting on an RV. The one in the RV-10 picks up VORs out to 100nmi at altitude.

Carl

BobTurner · #8 10-06-2017, 10:42 AM

+1 (as I said in my PM to the OP)

Bill Boyd · #9 10-06-2017, 11:36 AM

worth substantially less than Stein's $.02

simply what I'm going with as a first effort...

not flying yet and won't be for a good while...

similar has worked for me and others on ham VHF mobile, so I'm reasonably hopeful.

top pic shows the vee dipole VOR/LOC/GS antenna in the mid-section of the cabin top, with feedline and "bazooka" style balun of RG-400. The ends are about halfway down the doorway B-pillars. Legs are 26".

bottom pic is the 23" quarter-wave foil monopole Com 2 antenna in the right rear cargo area. This will be connected by very short pigtail to a BNC bulkhead fitting in a tab attached to the right top longeron, to use the fuselage side as a ground plane/counterpoise. This antenna is about 3/16 wavelength from the metal of the baggage area turtledeck skin, and fairly close to the right rear seat occupant. Because of the risk of RF exposure, this will be known as the mother-in-law seat. Just kidding - we're way below field strength concerns here.

czechsix · #10 10-06-2017, 05:01 PM

One thing I noticed about Bob Turner's installation is that he attached the antenna ground plane to the top wing skin, and the outboard leg angles downward. This makes the most sense for the RV-10/14 wingtip. However the Aircraft Spruce info for the Archer com antenna says you mount it to the bottom of the wing skin and angle it upward. This is probably because the older horner style tips would have allowed better vertical orientation by attaching it to the bottom skin.

For those of you who were not happy with the installation in the RV-10, did you ground the antenna at the top skin or bottom skin?

Thanks,