Introduction
When I found out that Atomic Workshop produced a range of motors and cells to complement the Zombie flight profiler, I couldn’t resist building a model to try them out. I had the plan the little Keil Kraft Piper Super Cruiser kit, this was a lovely Bill Dean design, and one of the Junior Flying Scale range that came out in the ’50’s – many modellers will be familiar with them. My chosen set-up was the Voodoo 15 motor, 90mAh cell, and Zombie. I decided the Piper looked a bit small at its original 18in wingspan, so I enlarged the plan slightly to just over 20in.
Installation:
The Voodoo 15 and 25 motors come with a choice of beam or radial mounts. I chose the beam mount facility, as this means that if you have a removeabe top to the engine cowl, you get direct access to the mount screws. This makes installation easier, also thrust line adjustments are simple. You can also remove the motor from the model without having to detach the prop. I used a 1/20th” ply motor plate, with 2 little ply wedges glued in place under the motor mounts to achieve some down-thrust. Before mounting the motor I also elongated one of the mount holes slightly – this means that to change the side-thrust I simply have to loosen the (supplied) mount screws, offset the motor slightly, and then re-tighten. The Zombie was mounted behind the motor on the same ply plate, with double-sided tape, the charge plug can be seen ‘floating’ to the side of the Zombie. Finally the cowl was held in place with tiny magnets.
The Super Cruiser has quite a long nose, so I had mount the 90mAh cell right back under the trailing edge of the wing, under the dummy rear seat, to get the balance correct. One advantage with electric models over rubber power is that you can position the power-train components so that no extra ballast will be required to achieve the correct balance point. If you build a model with a short nose, you can try the ‘tray’ mount shown in the Luscombe Silvaire article on this site.
Worth mentioning at this stage is the super idle feature of the Zombie. This is easy to set up if you follow the instructions, but you do need to temporarily disconnect the cell, make sure you do this before you permanently build-in your battery and cover your model (I forgot this!).
Finishing
The model was finished in Esaki tissue, and airbrushed with Humbrol enamel paints, thinned with cellulose spirit. I used conventional masking tape to mask the trim, de-tacked slightly on my (grubby) hands. One point worth mentioning when airbrushing this model is that I sprayed the entire model cream first, then I masked the wing codes, before spraying red over the cream. This worked well, in fact the cream base-coat acted as a super undercoat, and meant that not much red paint was needed to get good coverage. I decided to carve a full length figure from foam, along with seats, detailed dash and door cards. I even carved a scale replica of a ‘Slicker’ vintage free flight model (with box) to go on the back seat.
Everything works nicely, and I set the model up with the factory 10 second delay after pressing the ‘go’ switch. This gives me plenty of time to steady my nerves and replace the engine cowl. The idle feature works a treat, with six seconds of idling before flight power is applied (this will look particularly impressive when the model ROG’s)
Flying
The only flying the model has done has been outside so far. Initially I tried low power for about 10 seconds on the second phase of the Zombie to check stability, and things looked good – with a long descending left circle. On opening the throttle on the first phase, she tended to wind-in to the left, applying a small amount of right rudder stopped this, but she then spiraled in to the right after the power dropped to the second phase. It was obvious that the model required some more right thrust, which I applied.
The next flight was really nice, with a strong climb (about 90% power) followed by a slow descending cruise on the second phase of the Zombie (about 50% power)…very pleasing. I am now waiting for a nice calm day outside, when I can increase the duration on the Zombie
When flying these models outside, it is not necessary to use both power phases of the Zombie, as you will not be looking for a scale type landing, but if you turn them both up, you have the potential for a 2 minute climbing power run…be careful!
Conclusion
With the advent of tiny hi-power LiPoly cells, electric power is now a viable alternative to rubber or C02 power for small free flight models. The Voodoo is a lovely precision made, smooth running unit, giving very good power to weight. Perhaps the most remarkable aspect of the finished model is its very low all up weight, just 29 grams – comparable to a lightly built rubber powered model, of this, the flight package (Zombie/Voodoo 15/90 cell/plugs and leads) weighed in at exactly 9 grams.
Up until now, there has been very little information available to the modeler on suitability of motors, cells, props etc. with the result that many people have been put-off electric power (myself included) because projects have failed due to sheer guesswork. Hopefully this article may help to steer some people in the right direction as to the size/weight of a typical Voodoo 15 powered model. I have almost finished my latest project, which is the 1/24th scale Dave Diels Douglas TBD Devastator, this is using the Voodoo 25, with a 130mAh cell, I will keep you posted!
Statistics
Model
Keil Kraft Piper Super Cruiser (enlarged)
Span
50.8cm (20 inches)
Mass
29g
Wing Area
358cm sq.
Wing Loading
8g/sq.dm
** STOP PRESS ** STOP PRESS ** STOP PRESS **
Demise of the Piper Super Cruiser!
On a recent flying trip to what is possibly the ultimate indoor flying venue in the UK – the airship hangars at Cardington, Bedfordshire, Richard was flying the Piper with both Zombie time phases maxed out for total motor run times in excess of 2 minutes. The Piper put in plenty of impressive flights, but the last ended with the plane becoming lodged some 80ft up in a canopy covering an airship in the other half of the hangar. There was no hope of recovering the craft but at least it was lost in style!
The Cardington hangars are truly impressive measuring 247m (812ft) long, 84m (275ft) wide and 55m (180ft) high. In the late 20’s, the hangars housed the R100 and R101 airships now Hangar 1 is in need of extensive repair.
