Anyone with both a cargo pack and lightning strike detector?

[n86121]

Originally Posted by patrolpilot

I should be adding a cargo pack to my 337G at my next annual and will need to move the Strike Finder antenna. Where is your antenna mounted? Pictures would be nice.

Many moons ago I found he only shop that actually skin-mapped the airplane correctly, Excel avionics in Hartford CT. When challenged, all the other shops just put it someplace that was convenient for them, degrading performance.

Stormscopes are radio receivers: the higher the noise floor at the antenna input, the less sensitive the signal received. The receiver turns down is gain to get some signal above the noise. The ideal installation therefore takes a stormscope antenna fed to a spectrum analyzer with engines running, no T storms within 250 miles, to search for a quiet spot on the airframe.

Thunderstorms are generally UP, so antenna should be on top.

Mine ended up over the pilots head.

I recall them saying they were seeing 50 VOLT spikes all over the airframe, which would have greatly reduced its sensitivity.

In a quiet spot, internal automatic gain on the receiver goes up, and they become MUCH more sensitive.

The pattern of RF noise on any given airframe will vary. In the wrong place and either sensitivity drops, or you are cahsing endless noise sources.

IF you can try feeding the antenna when off to some form of display and find a quiet place.

[n86121]

Let me add the stormscope antenna ended up sort of over the pilot's head on top.

Thunderstorms are overhead, after all.

And that was the "quiet place"

[patrolpilot]

Back to the antenna thing... Totally disagree with the overhead location. From the Insight Installation Instructions:
"2.3 Mounting the Strike Sensor:
The Sensor must be mounted on the bottom of the aircraft fuselage, with an Installer-fabricated doubler plate of a..."

I've been flying airplanes with lightning strike systems since 1975, Both 3M/Goodyear & Insight, and I've never seen an antenna not mounted on the bottom of the airplane.

My airplane is in annual, and the pack is being installed. The pictures are of the pack being fitted before refinishing.

[SteveG]

BFGoodrich Stormscope WX950 w/ antenna mounted overhead the pilot's seat.

[patrolpilot]

Looks like overhead...

[SteveG]

PP,

If your StikeFinder antenna is already in place and not physically obstructing the cargo pod mounting and you're happy with its performance now you might consider leaving well enough alone, at least until you have had a chance to fly with it and note any change in operation. The fiberglass pod should not be a significant radio frequency obstruction. I have both transponder and ADF antennas inside the pod with no noticeable degradation in performance. Seems like you've got nothing to lose by trying it out before getting carried away with relocation.

Regards, Steve G.

[JAG]

WX-8 Stormscope antenna is on top of my fuselage - see pic (big square one, port side, mid-cabin). Not sure if it works the same as Insight, but a quick test in the hangar is to use a hair dryer/heat gun or drill and see if it indicates (cheap motor arcing simulates lightening).
Jeff

[patrolpilot]

Originally Posted by SteveG

PP,

If your StikeFinder antenna is already in place and not physically obstructing the cargo pod mounting and you're happy with its performance now you might consider leaving well enough alone, at least until you have had a chance to fly with it and note any change in operation. The fiberglass pod should not be a significant radio frequency obstruction. I have both transponder and ADF antennas inside the pod with no noticeable degradation in performance. Seems like you've got nothing to lose by trying it out before getting carried away with relocation.

Regards, Steve G.

Thanks, Steve. The airplane is opened up for an annual, so now is the time to move antennas. I'd rather be certain of the installation and its performance, as thunderstorm avoidance is a constant here on the Texas Gulf Coast.