Ariel location and fixing – Part Deux

Mike, who has seemingly endless brilliant contacts called me the other day, having seen the ariel location post …. call me now .. was the message ….

Duly called and arranegd to meet Mike and mystery guest at the barn at lunchtime …

Mystery guest turned out to be a very nice chap called Chris who is the wiz at Jersey Airport for all things electronic … well, what he didnt know about groundplanes was definately not worth knowing ….

Both Mike and I had a 45 minute lesson, overview, revelation on what groundplanes are, how they work, how they work better ! and whats more Chris delivered in easy to digest language …

So – Plan 2 –

Scrap the metal bar across the cabin – so two small rivets will be drilled out and then the bar removed. It WILL work and probably absolutely fine around the circuit … but as pretty much every single flight I do involves filling tanks, filing a couple of flight plans and submitting gendecs to whichever police force decide they need them as well as the local authorities … anyway .. suffice to say I need a radio that will still work around 50N as I cross the Channel ….

The new plan is to use the aluminium sheet base plate roll that Chris very kindly provided and cover the entire top of the cabane with it to provide a continuous sheet that effectively maps a circle (the radius of which matches or exceeds the length of the steel whip Ariel.

Chris also provided a link to a PDF that has a whole chapter dedicated to JUST this topic. So the aim will be to lay the alloy sheet and then top it (to create a sandwich and smooth surface for covering) with 1.5mm sheet ply.

Did you know you can calculate the load on an Ariel by using the formula below !

D=0.000327 AV2

(The formula includes a 90 percent reduction factor for the streamline shape of the antenna.)
D is the drag load on the antenna in lbs.
A is the frontal area of the antenna in sq. ft.
V is the VNE of the aircraft in mph.
Example: Antenna manufacturer specification frontal area = 0.135 sq. ft. and VNE of aircraft is 250 mph.
D=0.000327 x .135 x (250)2
=0.000327 x .135 x 62,500
= 2.75 lbs

OK – If the Sherwood is doing 250 mph – the reception of the antenna is pretty academic as I would have already lost all 4 wings !!! 🙂