A Flying Fireball XL5 Model

FIREBALL XL5 - A FLYING MODEL!! By Al Foot Photos by Al Foot I’ve been a life-long Fireball XL5 enthusiast, and have been reliving my childhood by watching all of the episodes on the Carlton DVD collection. Even now, there are some aspects that are ahead of this time, let alone the 1960’s when the originals were screened. The main star of the shows was, without a doubt, Fireball XL5 - a vehicle capable of flying through atmospheres, leaving the Earth, travelling through space to other worlds, and returning safely without so much as a singe on the outside skin!! Obviously a very advanced machine!!
	The engineers that designed it must have been advanced thinkers too, and, with this in mind, I wanted to test the concept by designing a radio-controlled flying model of XL5. As you can imagine, there had to be a few compromises in the design to ensure that she would fly, these being mainly in the wing, fuselage and fin sections (yes I know that’s basically everything!!). I made the fuselage as a flat plate side profile and a flat plate top/bottom profile so that the assembled cross section was, well…. a cross!!
I used Robin’s 3-view diagrams of Fireball XL5 as a basis, and, with my aeromodelling hat on, decided on a model size that would suit the propulsion and control system that I wanted to use. There have been huge advances in miniaturisation of radio equipment recently at reasonable cost. Similarly, electric motor technology for models is evolving at a pace. I actually make my own motors now, and used one of these to power my model of XL5. I tried to remain reasonable faithful to the shape, but please bear in mind that this is the prototype, and I did not want to invest too much time and effort. Similarly, the wings, fins and Fireball Junior fins were all flat plates.
I won’t bore you all with the thinking processes that I went through before attempting to fly Fireball - suffice to say that the balance point of the machine needed to be right or else she would be uncontrollable. Similarly, the aerodynamic means of controlling Fireball had to be derived since I would not be able to use the thrusters as per the original!! She first flew on 9 Sept 2005, after which I had to add additional fins and rudders to get some measure of control - you can see these in the photos, but I tried to make them as unobtrusive as possible. In flight, you hardly notice them at all. The movies show the third and fourth flights, before and after adding the additional fins. The improvement in control is obvious!!

Fireball XL5 has now done about 10 flights, and I’m now getting used to the somewhat unusual flying characteristics. (For those that fly radio-controlled aircraft, if you imagine a “normal” aircraft but with the fin at the front instead of the back you will not be far from understanding how Fireball XL5 flies!! ). I hope you agree that she looks great in the video clips, and it was certainly worth the effort!! She certainly causes a stir every time that I take her up to the airfield.
Now that I know that she flies, I intend to add a few more details, and I might even build another!! I hope that you enjoy my flying model of Fireball XL5. Best regards, Al Foot

		Technical details Length 36 inches Span 16 inches Radio control - 4 channels operating triple rudder, elevons and motor Power - small outrunner brushless motor and Lithium Polymer 3 cell battery Building material - 3mm Depron sheet (fine grain expanded polystyrene) with balsa reinforcement, carbon fibre spars Weight - 8 oz

Here are the movies of the third and fourth flights, plus a movie of a November 2005 flight.

rcxl51.wmv(380k)	rcxl52.wmv(0.98Mb)	rcxl53.wmv(1.39Mb)
Back to Features Page Back to Unity City Main Page