Slow-Motion Charger
— Bill Evans
Want to be whisked into the realm of silent flight? Converting your glow-powered Slow Motion to electric is one easy way. Choose from three Astro Flight cobalt systems that have been successfully tried. Each is quickly and simply installed.
The response to the Similar Slow Motion construction article in the January 1987 issue of Model Aviation has been overwhelming. Many modelers have called and written to tell me how pleased they are with their Slow Motions. Many others have inquired about the electric version mentioned in that article. Readers who want to learn more about converting the Slow Motion to electric should find the following information useful.
Electric power options
To date, Electric Slow Motions have been successfully powered with three sizes of Astro Flight cobalt systems:
- Cobalt 05 (geared)
- Example: Joe LeRoy's model weighs 64 oz. and has a wing loading of 14.5 oz./sq. ft.
- Installed as a geared 05 turning an 11 x 7 prop on seven cells.
- Provides a fairly good climb rate; trimming the model to about 50 oz. with this power combination makes an excellent soaring ship.
- Cobalt 15
- My first installation used an Astro Flight cobalt 15 on a 12-cell, 800-mAh pack swinging an 8 x 4 prop.
- The Charger weighed 4 oz. less than my .15-size glow-powered Slow Motion.
- Test runs produced about 15,000 rpm for the first 1-1/2 minutes, 13,000 rpm for the next minute, and 9,000 rpm for the balance of a four-minute run.
- Flight performance was excellent: good climb, easy loops and rolls. 600-mAh packs also gave more than satisfactory results.
- Cobalt 25 (direct-drive)
- Installed in a 14-cell, 1,200-mAh pack turning a 9 x 5 prop at about 12,000 rpm for almost six minutes.
- Total weight of the 25 version is about five pounds, translating to a wing loading of 18 oz./sq. ft.
- Verticals are a cinch and the model soars nicely; several one-hour-plus flights have been logged.
Installation
Modifying the Slow Motion for Astro Flight cobalt power is straightforward. Assuming the model was built according to the construction techniques shown in the 1987 article, follow these steps:
- Use the appropriate-size Astro Flight radial mount for the selected motor.
- Using the mount as a guide, mark and cut out the firewall for motor clearance.
- Measure the length of the motor as it rests in its mount, allowing for prop clearance at the front of the fuselage, and set the firewall at this distance.
- The mount has four screw holes for installation on the front of the firewall. Note that the motor is pushed in from the rear of the firewall and is secured in its mount by a setscrew.
- Cut a large hatch in the top of the fuselage to facilitate installing and removing the battery pack.
Cooling
Batteries generate heat during running and discharge, so provide cooling airflow around the pack. I installed an air intake on the right side of the fuselage and an air exit on the left side. This allows plenty of cooling air in and around the battery pack.
Conclusion
Converting your Slow Motion to electric is that simple. Decide on a power option, follow the few installation suggestions above, and the realm of silent flight can be yours.
Transcribed from original scans by AI. Minor OCR errors may remain.
