Skybolt Al
Well Known Member
Thinking about locating the antenna in the fuselage, behind the baggage compartment. That's how I've done it before in the Stearman, will it work OK in the metal airplane?
Van's Air Force
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ELT Antenna Location
- Thread starter Skybolt Al
- Start date
Sam Buchanan
been here awhile
Yes, for saying you have installed the antenna.
No, for having an antenna that will actually transmit a readable signal.
The Stearman installation may have worked ok due to its fabric skin (but if PolySpray was used in covering process the antenna was under a layer of aluminum powder...).
The RV's aluminum skin serves an an effective RF barrier.
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jetjok
Well Known Member
I know that it is desirable to have nothing protruding into the wind stream, but due to the facts that Sam put forth, decided to put mine just behind the canopy. Since the best hope of being heard now rests with passing airliners, I thought it would give me the best transmission.
What about putting the antenna in the cap of the vertical stabilizer?
Skybolt Al
Well Known Member
Where does everyone put the antenna?
Looking at all the RV's at Oshkosh, I don't remember seeing a single ELT antenna on the exterior. I just hate to put such an ugly thing on the outside.
Looking at all the RV's at Oshkosh, I don't remember seeing a single ELT antenna on the exterior. I just hate to put such an ugly thing on the outside.
Sam Buchanan
been here awhile
Well.....since you asked, here is where I mounted the antenna in my RV-6:
It ain't "legal", and not sure how well it works, but.........
ScottHess
Member
Just think about whether it was worth the looks and speed as you sit there upside down after your off airport landing into a wet sod field... waiting for someone to come and let you out. 
Mine is next to the rear passenger seat back almost touching the canopy. Not as good as outside though.
Mine is next to the rear passenger seat back almost touching the canopy. Not as good as outside though.
Sam Buchanan
been here awhile
Just think about whether it was worth the looks and speed as you sit there upside down after your off airport landing into a wet sod field... waiting for someone to come and let you out.
Mine is next to the rear passenger seat back almost touching the canopy. Not as good as outside though.
Yep, if you end up upside down with the turtledeck-mounted antenna buried in the mud............this topic has been beat to death in numerous previous threads for years.
There just isn't an ideal location for an ELT antenna on our RVs. Try finding an external location on an RV-8!
Sam Buchanan
been here awhile
True, but most builders don't want the weight of the ELT in the wingtip. If the ELT is mounted in the cabin, the long coax run out to the wingtip is likely to be compromised in a crash....
az_gila
Well Known Member
Well.....since you asked, here is where I mounted the antenna in my RV-6:
It ain't "legal", and not sure how well it works, but.........
Mine is mounted very similarly to this, and I can tell you that it transmits very well. I must have shorted some wires together wiring some under the floor, and I triggered the ELT by accident. Couple of days later DHS came looking for the signal, and that was through a metal hanger.
Hans
Ugly?
Here's mine, just forward of the VS and I don't think it's that bad/ugly!
http://www.airliners.net/photo/Van's-RV-7/1724601/L/&sid=49f0a7dfee6feddd6bf0192fe6c4831b
Here's mine, just forward of the VS and I don't think it's that bad/ugly!
http://www.airliners.net/photo/Van's-RV-7/1724601/L/&sid=49f0a7dfee6feddd6bf0192fe6c4831b
flickroll
Well Known Member
Precisely the problem for the new 406 MHz ELT's, although the Kannad 406 just might work with a couple of their antennas....
ELT Antenna
Mine is mounted like Sam's and I know it is not the best position. I discussed this with 2 different manufacturers at Oshkosh and they both said they would prefer it mounted horizontal and protected rather than vertical and unprotected. The most common failure to activate in a crash is damage to the antenna.
Ken
Mine is mounted like Sam's and I know it is not the best position. I discussed this with 2 different manufacturers at Oshkosh and they both said they would prefer it mounted horizontal and protected rather than vertical and unprotected. The most common failure to activate in a crash is damage to the antenna.
Ken
Sam Buchanan
been here awhile
Here's mine, just forward of the VS and I don't think it's that bad/ugly!
http://www.airliners.net/photo/Van's-RV-7/1724601/L/&sid=49f0a7dfee6feddd6bf0192fe6c4831b
That is a gorgeous airplane!
Really like the silhouette of an eagle taking flight on the mountains in the background.
Skybolt Al
Well Known Member
Gorgeous!
Steve:
I could stick antennas all over your plane and it would still be gorgeous.
Here's mine, just forward of the VS and I don't think it's that bad/ugly!
http://www.airliners.net/photo/Van's-RV-7/1724601/L/&sid=49f0a7dfee6feddd6bf0192fe6c4831b
Steve:
I could stick antennas all over your plane and it would still be gorgeous.
Neal@F14
Well Known Member
I've only seen two plane crash sites up close and personal in my 12 years of flying. The ELT antennas ended up in a horizontal position in both. The vertical mounting "legal" requirement is not IMHO based on reality since there's no guarantee what direction it'll be pointing in a wreck. I agree with Ken's post above where the antenna is best to be in a protected location no matter what polarization.
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RVbySDI
Well Known Member
I do not have pictures of my installation but I have my antenna mounted just behind the passenger seat on the right side baggage compartment horizontal rib. The antenna sticks up just shy of the canopy. I figured in this position I could keep the orientation vertical, it is protected from damage in the event of a crash and it is not out in the airstream. I mounted the ELT unit behind the rear baggage bulkhead on the intersection where the rib on the floor that the elevator bellcrank bolts to and the first bulkhead aft of the rear baggage bulkhead. Then I drilled a couple of holes through the vertical bulkheads, inserted snap bushings and ran the coax cable forward to the antenna. The one drawback to this ELT position is that it is not easy to get to in the event of a crash and you want to manually transmit with it.
az_gila
Well Known Member
Regardless of the antenna...
...position - if you have to thread the antenna cable through bulkheads, etc., don't treat it like normal avionics cabling.
If there is a major accident, and the fuselage becomes deformed, it would be easy for the antenna cable to get cut. Allow lots of slack in the cable, and no really tight clamp down locations.
One option is to use a section of Vans plastic conduit, and have an excess of cable at each end.
The above is applicable to both 121.5 and 406 ELTs, perhaps even more so for the 406 units, since the antennae are probably (my guess) more critical.
...position - if you have to thread the antenna cable through bulkheads, etc., don't treat it like normal avionics cabling.
If there is a major accident, and the fuselage becomes deformed, it would be easy for the antenna cable to get cut. Allow lots of slack in the cable, and no really tight clamp down locations.
One option is to use a section of Vans plastic conduit, and have an excess of cable at each end.
The above is applicable to both 121.5 and 406 ELTs, perhaps even more so for the 406 units, since the antennae are probably (my guess) more critical.
RVbySDI
Well Known Member
Good point. I guess there really is no simple answer to mounting these units. Perhaps I should look at a mounting bracket somewhere in the baggage compartment for the ELT that would allow a direct antenna connection to the unit without having to run through any of the airframe structure. Perhaps I could devise a mounting bracket just behind the passenger seat where the ELT could reside. That might be a good location in my plane.
ELT antenna cable should NEVER be run through a bulkhead in the conventional manner. As stated before, if the bulkhead is deformed, it can easily cut through the cable. Whenever possible the cable should be run through the large opening in the bulkhead and secured to the bulkhead loosely.
Dang it Mel. You're right again and just yesterday I ran my cable through one of the big lightening holes in the bulkhead one bay behind the baggage (RV-10). Luckily it's not closed up & will take about two minutes to reroute. I had it suspended like you say & my pea brain said to run it through the hole for "security". I hate this forum.
Part 91.207:
"91.207(f) Paragraph (a) of this section does not apply to--
(3) Aircraft while engaged in training operations conducted entirely within a 50-nautical mile radius of the airport from which such local flight operations began."
"91.207(f) Paragraph (a) of this section does not apply to--
(3) Aircraft while engaged in training operations conducted entirely within a 50-nautical mile radius of the airport from which such local flight operations began."
RVbySDI
Well Known Member
cfiidon
Well Known Member
Food for thought
Has anyone given any thought to perhaps imbedding a 1/4 wave dipole in the fiberglass fairing for the tail? If positioned correctly, this should be a bit better than an antenna inside the tail cone, as far as shielding goes.
Of course, you would need to pass a portion of the antenna connection through an area that might risk deformation, but this area is substantial where the vertical tail connects.
It seems no place is ideal, we just need to mitigate the risks as much as possible.
Don
Has anyone given any thought to perhaps imbedding a 1/4 wave dipole in the fiberglass fairing for the tail? If positioned correctly, this should be a bit better than an antenna inside the tail cone, as far as shielding goes.
Of course, you would need to pass a portion of the antenna connection through an area that might risk deformation, but this area is substantial where the vertical tail connects.
It seems no place is ideal, we just need to mitigate the risks as much as possible.
Don
Neal@F14
Well Known Member
91.207(f)(9) also excludes single seat airplanes, so the RV-3s don't need no steenkin' ELT either
Curiously enough, the opening clause of 91.207(a) also specifically says "airplane" and not "aircraft" so I guess that means that a helicopter, even a 4-seater carrying pax, is exempt too?
dhall_polo
Well Known Member
elt antenna location for tip up -7
Here's mine. I'm not the first nor the last to do it this way.
Here's mine. I'm not the first nor the last to do it this way.
sglynn
Well Known Member
hole in HS spar
Sam, I mounted my ELT antenna in the same place on my RV7. I like the location. And I put a #6 screw in the same place you did to hold the antenna, but on after thought I'm wondering if that hole compromised the HS spar. Might you have checked this out when you mounted yours?
Well.....since you asked, here is where I mounted the antenna in my RV-6:
It ain't "legal", and not sure how well it works, but.........
Sam, I mounted my ELT antenna in the same place on my RV7. I like the location. And I put a #6 screw in the same place you did to hold the antenna, but on after thought I'm wondering if that hole compromised the HS spar. Might you have checked this out when you mounted yours?
