Radio Control: Giant Scale
John A. de Vries Colonel, USAF, Ret. 4610 Moffat Ln. Colorado Springs, CO 80915
The Word on Kill Switches
There's always somebody who doesn't get it—worse when well-meaning friends pass on erroneous information. A new friend recently asked whether a kill switch was necessary for a modified chainsaw ignition engine he intended to install in his Giant. Short answer: HECK, YES.
He'd been told by some "experts" that a kill switch would interfere with his radio. That is incorrect. A kill switch simply grounds the high-tension (HT) coil to stop the engine; it does not interfere with radio operation when wired correctly.
I recommended he install two kill switches in parallel for redundancy: a manual SPST switch located where ground crew can reach it safely, and a servo-controlled microswitch actuated by the throttle pushrod in the full-low position. For the weight of a common wheel collar you get a reliable backup system.
How to wire it:
- Connect an insulated wire from the grounding lug on the engine's HT coil to a single-pole, single-throw (SPST) switch (SW 1).
- The other side of the SPST goes to a wire grounded to the engine (a mounting bolt or other point on the crankcase).
- Optionally mount a microswitch (SW 2) on the back of the firewall near the throttle pushrod hole. Slip a wheel collar on the pushrod so that at full Low it closes the microswitch and grounds the coil.
- Verify Off/On indications on the switches are correct—wrong orientation can leave you cranking for hours with no pop.
Suggested switch arrangement:
- SW 1 — SPST switch (manual)
- SW 2 — Microswitch (servo-controlled on throttle pushrod)
- Ground — engine crankcase/bolt
Locate the manual kill switch where it won't tempt anyone to reach through the prop arc to operate it.
Noise Traps on Servo Leads
Some readers ask whether noise traps are necessary on servo leads. The answer: it depends.
For Giant builders we commonly use multiple servos (aileron servos, doubled elevators, doubled rudders). Long servo leads, especially Y-type leads for doubled servos located far out in the wing or well aft in the fuselage, can act like antennas and compete with the radio's antenna. If a servo lead's length approaches the length of the receiver antenna, RF pickup can cause erratic or total loss of radio reception.
Notes and precautions:
- Some radios are immune; others are very sensitive.
- Receiver antenna position matters—placing a receiver antenna parallel to a long servo lead almost guarantees interference.
- If you experience range loss or erratic operation, install stick-on ferrite noise traps on the offending servo leads and/or re-route antenna and leads to avoid parallel runs.
Brave modelers sometimes install everything first and add traps only if problems occur, but that risks having to reopen the model to retro-fit traps.
News & Resources
- Bill Hannan has published Peanuts & Pistachios No. IV with excellent drawings suitable for conversion to Giant Scale, including: 1920 Kinner Caravan, 1936 Miles Sparrowhawk, 1911 Blériot Scout, 1966 Evans VP-1 (Volksplane), and 1969 Bede BD-4. Also two Pistachio drawings of the 1912 Canard and the 1918 Hergt. Price: $5.50 plus $1.50 P&H to Hannan's Runway, P.O. Box 80.
- Radio Control Scale Aircraft (quarterly), edited by Dave Boddington (England), recently devoted an issue to the Albatros D.Va, including full-size plans for a .60-powered version and articles/plans for a quarter-scale example, plus articles on Spandau guns and WWI lozenge camouflage. Argus Specialist Publications, P.O. Box 35, Wolsey House, Wolsey Road, Hemel Hempstead, Herts, HP2 4SS, England. Airmail for less than 1/2 oz. costs about $0.45.
- Emil Neeley at Ikon N'West has plans for a sporty Stinson SR-8 Gullwing (5 ft span / 100 in) for Super Tigre 2500s and a Sperry Messenger biplane—both suitable for Giant conversion. Contact: Ikon N'West, P.O. Box 306, Post Falls, ID 83854.
- Miniature electric motors with planetary reduction gears used by Bill Shear for Giant B-17 retracts are available from Emerald Science & Co., stock number 36837. Price: under $10 each.
Final Notes
Always verify wiring and switch orientation before running engines. Proper kill-switch installation and attention to servo lead routing or noise traps will greatly reduce the chance of a preventable mishap or radio interference problem.
Transcribed from original scans by AI. Minor OCR errors may remain.
