Author: Don Grissom
Edition: Model Aviation - 2011/05
Page Numbers: 116,117
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William Drumm's experiments with electric SSC

It is sometimes amazing to see the advances that have been made in electric-powered Combat in the past few years. Every year it seems as though more people are trying electric power for Slow Survivable Combat (SSC).

Last year William Drumm was one of the top SSC pilots. He flies an airplane that he designed and built at his home in Wisconsin. Following is information about the setup he used and his testing at the Tangerine Combat Challenge.

Electric SSC setup

  • Motor: Turnigy 3536-1400 kV
  • Speed control (ESC): Turnigy K-Force 40A (initial); Phoenix ICE 50 (for governor testing)
  • Battery: Turnigy 4S 2650 (Nano-Tech batteries also tested)
  • Initial measured speeds: ~16,800 rpm (initial test), 18,100 rpm after endpoint adjustment
  • Target governor speed: 17,500 rpm

William described his first venture into E-SSC and the testing process. After the initial test flight he measured ~16,800 rpm, then bumped the endpoint and hit ~18,100 rpm. He planned to try the Phoenix ICE 50 speed control and set rpm to 17,500 to see how it felt through an entire round, hoping the battery would hold that speed throughout the flight. From the data he’d seen, 17,500 rpm through the loops would be beneficial, although it would change how the motor unloaded in level and diving flight.

Governor mode and ESC setup

William experimented with the Phoenix ICE 50 in Governor mode:

  • He had trouble getting the motor to spin at first. He adjusted the number of magnetic poles in the ESC motor/gearing settings. Increasing the pole count increased rpm.
  • He calculated that setting the pole count to 14 was appropriate for his Turnigy 3536-1400 kV motor.
  • He tried a full-throttle target of 17,500 rpm; the ESC recorded 17,465 rpm for many settings. Middle-rpm setting of 17,000 rpm allowed some slowdown to match slower models; 14,000 rpm was about right for landing.
  • Recorded RPMs during one test: steady ~17,465 rpm with spikes up to ~17,570 rpm. On the field the readout showed 17,520 rpm before flying.

William liked the way the airplane flew in governor mode — it pulled well through loops and turns, and he thought Governor mode would give a consistent feel throughout the round.

He also ran into common transmitter/ESC setup issues:

  • Futaba transmitters require reversing the throttle direction for some ESCs. He tried that but still couldn’t get the ESC to arm initially.
  • He set throttle trim fully back and tried travels to 120% without success.
  • Adjusting the ESC motor poles (4 → 8 → 14) eventually got the motor running and at the desired rpm. After the correct settings the travels were back to 100% and trim didn’t need to be fully down to arm.
  • He recommends completely resetting the model in the transmitter if things behave oddly and ensuring you have the current version of Castle Link software for Castle ESCs.

He also noted that ESC settings don’t always get written properly. Under “Device Commands” in Castle Link you can read settings back to verify everything is set as intended.

Batteries, firmware and runtime

William tested Nano-Tech and standard LiPo batteries and experienced issues maintaining rpm:

  • With some packs he only got about 2 minutes at 17,500 rpm.
  • He discovered that one of his ESCs (ICE 50 Lite, no heat sink) showed a firmware update available in Castle Link (v3.26 Beta). He updated that ESC, but his other ICE 50 (with heat sink) was on v3.2.
  • After downgrading the updated ESC back to v3.2, performance improved: it held rpm for 3 minutes and measured about 17,150 rpm at the 5-minute mark.

William has posted graphs and more detailed information about his ESC setup on the RC Combat Association website, with useful links.

Tangerine Combat Challenge (Feb 19–20)

Since winter provides limited flying time for RC Combat, it was great to see William drive down to Florida for the Tangerine Combat Challenge. The event was hosted by the Remote Control Association of Central Florida (RCACF) at the Tangerine Field north of Orlando. The contest CD was Chris Handegard.

I caught a ride with Bob Loescher of Ohio. We usually wait until we get to Florida to get a hotel room so we can all stay near each other, but this time hotel availability was tight because we were about 45 miles from the Daytona 500 at Daytona International Speedway, so we were lucky to get rooms before the event.

Contest summary

  • Open B: 10 rounds, all-up because the club had enough judges. This allowed time between rounds to work on models. William Drumm was the top pilot in Open B with a very high score. I finished third.
  • 2948 Scale Combat: 5 rounds. This is one of the most exciting classes to watch. Many nice models were present, many built by Chris Handegard of Bullet Proof Models. A common model was a P-47N. Chris flew one airplane for the whole contest (surprising because it was a twin).
  • Notable model: J1N1-S Gekko (Irving) — one of the fastest in the air, powered by two Magnum .15 XLS engines. Wingspan was 60 inches (rather than the typical 48 inches for a single). Chris had occasional engine losses but managed to land with little to no damage.
  • Chris Handegard won Scale with the Gekko; Craig Buttery was second.
  • SSC: After Scale, SSC began — this was a test of William’s electrics. He started the contest with five models and ended up needing all five. The field was extremely sandy; sand got into components and was harder to clean on electrics than on gas engines. William flew strongly, earning many cuts and having few problems as long as he avoided midairs. He completed nine of the ten rounds (he didn’t need the tenth to win).

After the event William called the outing a success for electric power in Combat. Durability issues remain, but electric power appears to be a promising direction for the sport. The RCACF ran a good event with many club members helping at the field.

Sources

Transcribed from original scans by AI. Minor OCR errors may remain.