PilotAware
British Forum => Technical Support => Topic started by: malcolmR on March 04, 2021, 08:55:54 pm
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just acquired a PW with external aerials planning to install in a tiger moth. We have not found anyone else who has made such an installation. We were planning to install aerials in the forward floor of the front cockpit. I have just been reading in other posts about relection and obscuration associated with undercarriage legs. The tiger moth alighting gear is a bit of rats nest of metal tubes -see attached. Am I likley to get a reasonable performance with the aerials just behind the forwrd sloping radius rods or are we wasting our tim?
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Hi Malcolm,
External antennas under the cockpit floor is good. Remember that the antennas need a metal ground plane. I presume that area is made of metal? If not you’d need to install a thin aluminium sheet inside the outer skin on which the antennas should be mounted. This can be two separate sheets (one for each antenna) or combine both into one. Size isn’t critical, but I’d suggest somewhere around 100 to 150mm square as a minimum for a single antenna or equivalent scaled up for two. (Bigger is better).
The other basic premise is to try to keep antennas as far as practicable away from any other large chunks of metal as signals can’t pass through it, so if the radius rods are the silver bits (sorry not an expert on Moth Speak), I’d try for a point midway between the top end of those and the top of what I’d call the main undercarriage ‘legs’. Nearer the nose shouldn’t be a problem - though the closer you get to the radius rods the greater the potential obscuration due to the percentage of the antenna they will block. Also try to keep the antennas as far apart as possible but still on the flat bodywork where they still both point vertically down.
Hope that helps.
Regards
Peter
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Malcolm. Had the PAW Aerial fitted underside to aluminium bottom panel that extended backwards from firewall. It was 'vertical but upside down and it worked fine.
GPS Aerial had extended lead from PAW to dongle and was placed on the Instrument Panel coaming. ADS-B aerial was fitted on top forward aluminium panel and was shortened to about 10cm max. In the end it was about 7cm. Worked very well too. It was a rag and tube build with front section of aluminium panels.
Gerry