Anyone with both a cargo pack and lightning strike detector?

patrolpilot · #1 07-23-20, 11:24 AM

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.

n86121 · #2 07-26-20, 03:13 PM

Quote:

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 · #3 08-29-20, 10:46 AM

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 · #4 03-14-21, 05:57 PM

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 · #5 03-15-21, 11:29 AM

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

patrolpilot · #6 03-15-21, 12:26 PM

Looks like overhead...

SteveG · #7 03-15-21, 02:42 PM

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 · #8 03-15-21, 03:25 PM

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 · #9 03-16-21, 07:47 AM

Yeah, looking like the top, even though it is against what Insight states. Maintenance will do the skin mapping. If we get a chance, thunderstorms are forecast next couple of days, would like to tow the airplane in a circle to make sure the WX remains stationary as my display is slaved to the aircraft heading.

I had a WX-10 in my "commute-mobile." I flew this PA-22/20 back and forth from South Texas to Hobby for my airline flying. The commute up was always at 1 pm, and back, 1 am. Those commute times would light up the display. 1200+ commutes taught me the value of a lightning strike system.

http://www.337skymaster.com/messages...9&d=1568469918

patrolpilot · #10 03-16-21, 07:55 AM

Quote:

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.

patrolpilot · #11 04-21-21, 08:26 AM

Providing follow-up on my topic. We did find the perfect belly location for the antenna. There is an inspection plate immediately aft of the pack.

patrolpilot · #12 05-20-21, 10:20 AM

A bit of follow-up concerning the location of my StrikeFinder antenna.

When I spoke to Insight, a guru said to put it on the bottom for optimum reception. He said in storm detection, and we forget a simple thing about a lightning bolt. The charge moves from cloud to ground, but the voltage of the strike is produced where the negative charge meets the positive (earth or another cloud). The greatest voltage, which a strike system measures, is at the ground during ignition.

The pack had been outlined on the airplane's belly, so the mechanic pulled an inspection plate off that was immediately aft of the pack; there was plenty of room, so a 15' cable was made and the antenna mounted on the plate. The image is attached to the post above.

Last weekend was a proving run from my airplane, with a flight along the Gulf Coast to FL and back. The return, crossing from AL into LA, proved the SF installation was worth the thinking.

The SF (and approach controller) did a great job of presenting me with a path to join the approach. I have ADS-B In, like most, but you darn sure do not want to use it for this tight work. In the attached ILS image, the weather displayed is actually slightly east of the displayed position; the ADSB delay and the Insight StrikeFinder (ATC) confirmed the wall of the weather was just east of the final approach course.

The Strike Finder continued its good work with the flight into Texas. After that, I had to go offshore and then east. But, again, the SF helped me wiggle my way through the weather about midway rather than take a larger deviation further south.

My Strike Finder is an early unit with the liquid plasma display; when fall approaches, I'm going to send it back upgrade to the ultra-bright LED display.

Also, as a serious Gulf Coast flier, I'm going to go ahead and make the switch from ADSB-In to Sirius-XM. The update and transmission delays are too long for my taste, and I need ground coverage. Being based at VCT, I'm spoiled because of the antenna overlooking the ramp. I need the weather on departures and during the approach and planning an exit during a go-around.