Hearn's Sportster and Observer

[Wayne_H]

The Hearn Brothers ran a large Hobby Shop in Melbourne in the 50's through to the 70's. They also designed & produced a number of F/F and early R/C kits. AeroFred have 3 Hearns plans:
The Swift Team Racer C/L - https://aerofred.com/details.php?image_ ... ode=search
The Eagle F/F sailplane - https://aerofred.com/details.php?image_ ... ode=search
The All Australian Mk II C/L sport/stunt - https://aerofred.com/details.php?image_ ... ode=search

A similar search - https://outerzone.co.uk/search/results. ... ord=hearns - on the Outerzone found 12 plans including the above 3 designs.

The Observer was the aircraft responsible for getting me into aeromodelling . My Dad built it when I was a babe in arms, and I found it in the attic in dis-repair about 9 years later. With Dad's encouragement, I repaired(?) it and with my cousin's help(?) attempted to fly it. The rest, as they say, is history

Sadly, my Dad passed away 2 weeks ago, and while with my siblings preparing for Dad's funeral, I re-discovered this picture of Dad with his newly completed Observer, powered by an E.D 1.46 (which I still have).

Alas, I have never been able to track down an electronic copy of the Observer plan, but I do have a hard copy carefully packed away somewhere in storage . Last year, while relaxing on a cruise, I started converting the Sporster plan to make it look as much like the Observer as my memory could recall. While at it, I made a few minor mods to improve the single channel performance --> increased the fin area to reduce spiral instability, added a rudder, moved the CofG forward, thinned down the tail-plane and made it symmetrical.

screen grab of the "Sports Observer". The wing TE mods are not yet finished (hint - look closely at the photo)

Hearnes_Sportster_single channel.pdf

(812.79 KiB) Downloaded 265 times

With Dad's passing, this project has moved right up the list. I think it would be an absolute delight puttering around at low altitude on a calm day or evening with a 1+1 or bang-bang radio. I shall keep you periodically updated on my progress........

[iflylilplanes]

Wayne, any idea of the year the Sportster was designed? I'm looking for Australian designs to build.

[Wayne_H]

Hey Dave,

As best I can establish, the Sporster was designed by John Lamont circa 1950 and kitted by Hearns Hobbies in the first half of the 50's. The Outer Zone has a number of pictures for inspiration - https://outerzone.co.uk/plan_details.asp?ID=608

In the pictures the Sporster looks a bit too "dumpy" for my likes - The Observer was definitely the more attractive of the two IMHO. The pictures have highlighted to me a few more changes I need to make to my conversion of the Sporster to an Observer.

If your looking for a glider for R/C conversion, have a look at the Hearns Bluebird - https://outerzone.co.uk/plan_details.asp?ID=5765
The twin fins will need a little engineering ingenuity with either bell-cranks or a 3gm servo in the tailplane, but for me its just sufficiently different, yet simple, to be appealing and its an Aussie design!

[Wayne_H]

Dave & anybody else interested in Australian vintage model designs:

Doing some more searching tonight I found this page - https://fullcircleflyers.blogspot.com.a ... bilia.html

which has plans for many Hearns kits as well as kit box artwork and a detailed history of the Hearn brothers. It even has the plan for the Observer that my Dad built which of course I have downloaded - you rippa!!

[iflylilplanes]

Thanks Wayne,
I have an enormous number of aircraft I want to build, the Observer looks the nicer of the two, and looks like it will be on the list. There are four aircraft on the list close to finished a Tomboy, Sharkface, Aeroflyte Invader and a Sterling J3 Cub, the first two are scratch builds, the other two are restorations, both built in the 1960's.