Author: Jim Hiller
Edition: Model Aviation - 2004/08
Page Numbers: 129,130
,

RADIO CONTROL JETS

By Jim Hiller, 6090 Downs Rd., Champion OH 44481

THEY'RE FINISHED, they've been approved, and by the time you read this, we will have been living with them for some time. I'm referring to our latest turbine rules. Let's discuss them so none of us is caught off guard.

Documents

Where do you get a copy? That's easy; go to the AMA Web site and work your way through to the documents section. You are looking for:

  • Document 513: "Safety Regulations for Fixed/Rotary Wing Model Aircraft Gas Turbines."
  • Document 538: "Turbine Applicant Flight Demonstration."
  • Document 576: "Pilot Turbine Waiver Renewal Affidavit."

Download all three.

Highlights

  • Turbine thrust limits: models may be powered by turbines with up to 45 pounds of thrust; twin turbines are restricted to a maximum of 50 pounds of thrust total.
  • The power-to-weight-ratio limit has been eliminated; the 200 mph speed limit is now the governing speed restriction.
  • New wording for stopping requirement: "The model shall be able to come to a controlled stop on command with the engine at idle on a level hard surface."
  • Fuel and shutdown requirements now specifically require two methods of shutting down the turbine: one manual and one remote.
  • Fail-safe/ECU requirement: turbines must be equipped with a radio and/or engine-control unit (ECU) that will bring the turbine to idle or preferably shut it off within two seconds of fail-safe activation (compliance deadline January 1, 2005).
  • Flightline safety: fire extinguisher and water-based fire-suppression equipment must be available; emergency-response preparations should be in place.
  • Pilot-waiver renewal: Document 576 (notarized) will be required annually starting with the 2006 AMA renewal, verifying at least 20 turbine flights in the preceding 24 months.

Twin-turbine power limits

The perspective has changed for twin-turbine power limits. The new maximum for twins is based on limiting the model's power when both turbines are running. The previous 70-pound-thrust limit was intended to provide a reasonable power-to-weight ratio after a flameout of one turbine. Under the new rule, if a turbine flames out on a twin, the pilot will have less reserve power and must use greater skill to bring the aircraft home safely.

Speed limit

The controversial 200 mph speed limit states that we are not to exceed 200 mph velocity. The power-to-weight-ratio limit has been removed because experience showed it was not the best limiter of speed—airframe drag proved more important. You can enjoy higher power-to-weight ratios, but you must use skill and discretion to obey the 200 mph limit. Even with 45 pounds of thrust, many airframes may not reach 200 mph, but the extra power is useful for accelerating out of slow, high-alpha flight. Use it wisely.

Brakes

The rule now requires that "The model shall be able to come to a controlled stop on command with the engine at idle on a level hard surface." I believe in brakes. Early on I flew 20 turbine flights without brakes (including 10 at the AMA National Flying Site) and was able to stop, but brakes make flying much easier and safer. I used soft tires and slight nose-gear drag to stop without brakes, but I don't want to go back to that setup. Brakes are great.

Fuel system and shutdown (Item eight)

Item eight continues to eliminate loose plastic tanks and also covers fuel shutoff requirements. Two methods must be in place to shut down the turbine: one manual means and one remote control method. As before, two independent methods of shutting down the turbine are required.

Fail-safe and ECU requirement (Item nine)

Item nine is good practice and requires that all turbine models be equipped with a radio and/or an ECU that will bring the turbine to idle or, preferably, shut it off within two seconds of fail-safe activation. Compliance deadline: January 1, 2005.

  • If you have a modern pulse-code-modulation (PCM) radio with fail-safe capability, program the fail-safe to shut off the turbine.
  • The two-year phase-in allows ECU manufacturers time to modify systems; many current ECUs already have this feature.

Shutting the turbine prior to a crash greatly reduces the chance of a post-crash fire, because a running turbine can be a source of ignition. Program your fail-safe to shut down the turbine; it makes a difference.

Flightline requirements

Flightline requirements now emphasize having a fire extinguisher and water-based fire-suppression equipment available on the flightline, and having emergency-response preparations in place. This is good practice for any modeling activity, not only turbines.

Pilot requirements and waiver renewal

For existing turbine-waiver holders:

  • Starting with the 2006 AMA renewal, you must submit Document 576 ("Pilot Turbine Waiver Renewal Affidavit") every year, and it must be notarized.
  • Document 576 requires your signature and that of another experienced turbine-waiver holder.
  • You must affirm that you have made at least 20 flights on turbine-powered model aircraft in the preceding 24 months.
  • Maintain a pilot log as proof that you are an experienced turbine pilot. A hand-written log is adequate; electronic logs (PDA/spreadsheet) are acceptable.

Document 576 is not required with the 2005 renewal to allow pilots time to complete 20 flights in the two-year period between initiation and implementation of the rule.

New turbine-waiver process (Section 22)

The new process for attaining your turbine waiver is intended to be more realistic. Last year's temporary procedure that allowed the use of a training cord and an experienced turbine-waiver pilot on the other transmitter proved successful, and the rules reflect that experience.

  • "Prior experience": Document 513 specifies 50 flights on a high-performance model capable of sustained speeds of 100 mph or higher (reduced from the previous 150 mph requirement).
  • The same model used for prior experience may be used for the turbine-waiver qualification flight, or you may use your turbine-powered model for the qualification flight.

An experienced turbine-waiver holder can assist an applicant pilot using the buddy-box system:

  • The apprentice holds the slaved transmitter; the experienced pilot uses the master transmitter.
  • The experienced waiver holder assists until, in his or her judgment, the applicant is ready to perform the qualification flight.
  • The applicant then performs the turbine qualification flight according to Document 538: "Turbine Applicant Flight Demonstration."

Turbine Applicant Flight Demonstration (Document 538)

The qualification flight consists of two parts:

  1. Verbal/ground portion
  • Demonstrate verbal understanding of the AMA turbine rules.
  • Discuss differences in turbine engine operation and actions during starting and shut-down procedures.
  1. Flight demonstration
  • Demonstrate flight skills, with particular attention to control during takeoff and landing.
  • The model must remain within 10 feet of either side of the runway centerline during the takeoff roll.
  • Perform a go-around to demonstrate handling the slower throttle response of a turbine. The go-around should be in the opposite direction of the landing, provided field conditions allow it. If the sky is crowded, winds are strong, or conditions prevent the reverse-direction go-around, it is acceptable to perform it in the same direction as the upcoming landing.
  • Perform a Horizontal Eight (see Scale competition rules to understand the maneuver). This demonstrates control in both left-hand and right-hand traffic patterns.
  • Demonstrate two aerobatic maneuvers; both must include looping and rolling elements. Acceptable examples: Cuban Eight, Humpty Bump, Split "S", or a loop with an immediate roll. Applicants will be judged on control rather than precision.

Closing

I hope this helps existing turbine-waiver holders and future turbine modelers understand the new rules. Let's go out and make them work for us. We have roughly 800 turbine-waiver holders, and based on turbine sales, more pilots have yet to attain their waivers. Those of us with waivers can help new pilots get into turbine flying—using their own models—so they too can obtain their waivers.

I thank the leadership of AMA and of our Special Interest Group, the Jet Pilot's Organization (JPO), for stepping forward and participating in this cycle of rules revisions. The leadership of JPO provided input from the jet-modeling community during the development and presentation of the proposed rules changes to the AMA Safety Committee and Executive Council.

Check out the JPO Web site at www.jetpilots.org to find out who we are and how you can join.

MA

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