internal or external Pilot aware antennas for a skyranger

[SafetyThird]

With the CAA grant for EC devices, I'm planning to get a Pilot aware unit for my sky ranger. Internal antennas are easier to fit but would external make a big difference in signal in a rag and tube aircraft like the sky ranger given that you can position them more ideally? How do you go about safely making a hole in the covering for the antenna to go through?

 

[Dave Morton]

Although this is purely guess work, would burning a hole with a soldering iron be ok?, reasoning behind this is that the edges of the hole will be "sealed" to a degree and prevent any material fraying that may occur

 

[SafetyThird]

Yes, that's the one idea I'd thought about but wondered if it would be a strong enough edge. Perhaps glueing an extra layer on first then burning the hole through would add some reinforcement

 

[randombloke]

The external antennas require a ground plane fitting, so you need to factor this into their location. I'm possibly going to use the very end of the windscreen behind the pilot and passenger heads with ground plane fitted as adhesive silver foil in the 20cm x 20cm squares recommended.

You might find that fitting internal antennas is easier, maybe they could go just forward of the door pillar below the dash? However, will this warn about approaching aircraft from in front, your biggest risk?

Remember that the engine is a huge metal lump and will give you massive obscuration forward if you hide the antennas under the dash, or place the PilotAware there with the antennas attached to it.

I'd be wary about making soldering iron holes in the fabric of any type, as it is often tensioned by both lacing and application of heat, and disturbing this would be a big mistake IMV.

One for Flylight Engineering. They're superb people and will tell you what's what.

 

[SafetyThird]

Thanks, I'll throw them an email.

 

[SafetyThird]

Had a reply back from Flylight as follows

"
You can fix a ground plane directly to the fuselage fabric - just make sure there aren’t any sharp edges / corners that can chafe - some double sided tape is a good idea to stop relative movement. You can cut holes in the fabric using a sharp knife (don’t slip!) or melt a hole with a soldering iron.

Regards
Paul Dewhurst"

I'm thinking that you'd want the ground plane on the inside of the fabric, secured with double-sided tape and the antenna mounted through it all with the nut on the indie holding it all together. Soldering iron to make a clean hole seems to be the accepted way of doing it after all

 

[Frank Dimmock]

Which aerials are you intending to mount externally?

The P3i aerial as supplied is a sleeve dipole so doesn't need a ground-plane, but for the ADS-B one a standard surface-mount transponder type would be the best bet and it will need a ground-plane. As Randombloke says, ally foil is ideal but by making it as big as reasonably possible reduces the radiation angle and will increase the horizontal range.

You might also want to include a thin sheet of ally maybe 200mm diameter to support the aerial if it's mounted only on fabric. That will help stop it fluttering in the airflow and damaging the fabric hole because of something called Vortex Shedding. Not sure if it would be a problem at Skyranger speeds, but could be a bad way to find out!

 

[SafetyThird]

Pilot aware do an external mount kit which you can see here https://www.pilotaware.com/product/external-antenna-installation-kit
Plan would be to mount a 20x20cm piece of aluminium sheet to the inside of the fabric with double sided tape, with a hole drilled through it for the antenna to mount to.

ADSB out would be through the transponder (trig21) which is already installed.

 

[Frank Dimmock]

I wasn't aware of the kit but looks a good option. I would still make the ground planes bigger if possible by using foil in addition to the support plate. Foil helps keep the weight penalty low.

Are you using a separate GPS for the ADS-B data or fed from the Pilotaware somehow? I think usually the data is RS-232 into the transponder.

 

[SafetyThird]

Thanks, will look into larger ground planes once I come to fit everything. Current plan is to feed the transponder with gps from the pilot aware. I know it only gives sil=0 but most things will still see and display that. I'm almost tempted to drop the extra £400 on the trig gps but that might have to wait a little while and I'm not sure it's worth it for a microlight. With the transponder, PAW and sil=0, I'm visible to almost everything except the big iron and, frankly, I'll be trying to stay as far away from them as possible

 

[Frank Dimmock]

I don't think the Pilotaware has RS-232 out unless you go to the hassle of an RS-232 to USB converter, but that can be fraught with driver issues etc. As you say, might be better to get the proper Trig GPS module although it's pricey. Most GPS units with RS-232 out should drive the Trig but not sure about the SIL category.

I think most heavy metal would be either very high above us or in CAS where we're unlikely to be anyway unless under ATC supervision of some sort. Where I am, we get all sorts low level, Hercs, Chinooks, Apaches, A400M plus Hawks, Tutors, Prefects and other odds and ends😬😁
MK1 eyeball supplemented by PAW is my setup at the moment.

 

[SafetyThird]

Mendelson pilot supplies offer a plug and play cable from the PAW to the TT21 apparently, about £50. Seen it mentioned on the PAW forums and seems to work well.

 

[Frank Dimmock]

That's good. I suspect at that price it's more than just a cable though as there's probably a level-shifter chip in one end to make it work.

 

[SafetyThird]

Just scored a brand new in box Trig gps with antenna for half price. Someone had bought one with the rebate and now not going ahead with the install so offered it at their cost, which is a cracking deal. Means I can get the PAW with my subsidy and the full sil=1 gps only costs me an £150 over what I would have paid.

 

[Frank Dimmock]

Absolute bargain, well done! 👍