Safety Comes First!

Safety Comes First!

We thought that the controversy over the maximum size of model aircraft had been resolved when the AMA Executive Council voted to adopt the same 55 lb. weight limit enforced by Canada and Australia. However, we have revised our thoughts after our attendance at the Council's October 23, 1982 meeting, the agenda for which contained no less than three items concerning maximum model aircraft size. These can be summarized as follows:

1. "Aircraft Size and Safety Guidelines," submitted to the Council as a proposal for adoption by IMAA, contain comprehensive guidelines for the construction and operation of giant-sized model aircraft. The section on wing loading suggests a maximum of 48 oz. per sq. ft., or a maximum model weight of 100 lb., whichever is least.

1. A letter from One-Eighth Air Force, written by Kent Walters, requests further study of the model weight limit with consideration of a weight limit in the 90-lb. range for multi-engine models if the present 44 cu. in. engine displacement limit (from 53.B.2 of the AMA rule book) is maintained.

1. Rules change proposal (Gen-84-9) submitted to AMA by Bill Northrop would establish 40 lb. as the weight limit for model aircraft.

By far the majority of readers who have corresponded with us on the subject of maximum model weight regard the current 55-lb. limit as too heavy. Rationale for this consensus differs; quite a number stated that they believed the Council acted in haste and should have based its decision on something more tangible than the Canadian weight limit. There are also proponents of a higher weight limit who feel, likewise, that little was explained about the reasoning for the 55-lb. limit other than "it was apparently the limit similarly imposed in Canada by MAAC and coincided with the Federal-imposed highway speed limit." We doubt that the Council based its decision on this latter limit.

Rather than reopen the discussion on maximum model size within itself, the Council has turned it over to the members of the AMA Safety Committee for resolution. This committee will be asked to consider all issues concerning model aircraft size requirements and report back to Council with a recommendation. Since we happen to be a member of the Safety Committee, we would like to solicit the opinions of readers. Let it not be said that the AMA makes snap decisions in some dingy basement room at Headquarters!

First, a look at the IMAA Safety Guidelines. These have been formulated by the IMAA Board of Directors, and the copy we received is in the form of a brochure with an introduction written by IMAA President Don Godfrey. IMAA is seeking recognition as a special interest group within the AMA structure, and since the association has over 3,000 members, it appears logical that it should be selected as the collective voice for the giant-sized model builder.

Don states the following in his introduction to the guidelines: "IMAA is presently working with AMA to formulate a reasonable attitude towards Giant Scale safety and regulation so that IMAA can be a viable asset to AMA within the structure of IMAA's very own organization. If IMAA cannot satisfactorily reach a proper conclusion to the problem of who-shall-make-Giant Scale regulations and to what degree, then IMAA will have no choice but to go independent."

The following are the proposed guidelines, which we understand will also be printed in the next issue of High Flight, IMAA's quarterly newsletter.

IMAA Aircraft Size & Safety Guidelines

Section I — Maximum Wingspan

Maximum allowable wingspan for gasoline-powered radio-controlled aircraft shall not exceed sixteen feet (16 ft.). A five percent (5%) override may be allowable for aircraft that, by a true nature of scale dimensions, exceed a 16-ft. span.

Section II — Maximum Wing Loading

Maximum wing loading shall not exceed 48 ounces per square foot of wing area, or one hundred pounds (100 lb.) of total aircraft weight, whichever is least.

Section III — Maximum Engine Size(s)

• Single-engine aircraft: 46 cu. in. maximum.
• Twin-engine aircraft: 83 cu. in. total.
• Multi-engine aircraft: 96 cu. in. total.

Do not attempt to exceed 12 pounds of aircraft per each cubic inch of engine displacement. All ignition engines, regardless of size, shall have on-board kill switches, either servo-operated or manual. All glow engines used on giant RC aircraft shall have an on-board system that will stop the engine by radio command. These requirements are mandatory.

Section IV — On-Board Fuel Capacity (minimum per engine)

1. 1.3 to 3.15 cu. in.: 16 oz. fuel tank.
2. 3.7 to 4.3 cu. in.: 24 oz. fuel tank.
3. Over 4.3 cu. in. engine: 32 oz. fuel tank.

Reserve fuel supplies eliminate deadstick landings.

Section V — Radio Equipment (minimum requirement)

• To be standard FCC-approved quality.
• Servos to be rated heavy duty with a minimum of 24 inch-ounce of thrust for non-critical control functions, and a minimum of 45 inch-ounce for stress functions. The use of one servo per each aileron and one servo each for stabilizer-left / stabilizer-right is strongly recommended. Use of dual servos is recommended.
• Batteries on-board shall be 1,000 mAh up to 20 lb., 1,200 mAh to 30 lb., 1,800 mAh to 40 lb., 2,000 mAh over 40 lb.
• Redundant and fail-safe battery systems are recommended.
• The use of anti-glitch devices for long leads is recommended.

Section VI — Mechanical Components

• Servo arms and servo wheels to be rated heavy duty.
• Control horns to be rated heavy duty.
• Control surface linkage, in order of preference:

1. Cable system, push-pull, pull-pull.
2. Golden Rod (Sullivan) push-pull.
3. Arrow shaft, fiberglass or aluminum, 1/4-in. and 5/16-in. OD.
4. Hardwood dowel, 3/8-in. OD.
5. Sig carbon rods.

• Hinges to be rated heavy duty and manufactured for giant RC aircraft use only. Homemade and original-design hinges acceptable if determined to be adequate for intended use.
• Clevis and attachment hardware should be heavy duty 4/40 thread and rod type. Rods of 2/56 thread size acceptable in most applications. Clevis to have lock nuts and keepers.

Section VII — Flight Testing and De-Bugging (mandatory)

All giant-type RC aircraft to be flown in any IMAA- or AMA-sanctioned events must have been flown, flight tested, and flight trimmed a minimum of six (6) flights before such aircraft may be safety checked and entered to fly.

Section VIII — Safety Check (mandatory)

All giant-type RC aircraft to be flown at any IMAA- or AMA-sanctioned events must be inspected and approved for flight by approved safety personnel.

In the event that any aircraft is involved in a crash or accident, no matter how minor, that aircraft will have to be inspected by a Safety Officer and once again approved for flight, provided that the aircraft is repaired and made ready for additional flying at the same entered event.

Section IX — Proof of Flight (mandatory)

Must be submitted at IMAA- and AMA-sanctioned events by:

1. Submission of photographs showing aircraft in flight, or
2. Signature of builder/flier attesting to this fact.

Section XI — Aircraft Exceeding Max Size Regulations (mandatory)

Aircraft that exceed a wing loading of 48 oz. per sq. ft., or 100 lb. total may be flown at IMAA- or AMA-sanctioned events under the following conditions:

1. Proof of adequate insurance (special policies, etc.).
2. AMA and FCC licenses required.
3. Event sponsoring organization has purchased additional insurance covering the pilot (operator) and spectators for a minimum $1 million of liability coverage.
4. Spectators shall be assembled no less than 100 ft. from flight line.

(No prize is being offered for the first person to tell us that Section X has been omitted. We have deliberately kept the IMAA numbering system to avoid any confusion when (and if) we receive comments.)

The second item concerning model aircraft size limits is the letter from Kent Walters written on One-Eighth Air Force stationery and sent to AMA President John Grigg. We understand that the entire letter has already been published in one of the other model magazines.

To conserve space, we are therefore not reprinting that entire letter. However, if anyone desires to receive a copy, a SASE to the address at the end of this column will bring you one. Basically, what Kent is suggesting is a weight limit of around 90 lb. for multi-engine scale models. His rationale is to permit modeling a multi-engine aircraft to the same scale as a number of popular .60- or .90-powered single-engine models. He claims that a multi-engine bomber would have about six times the weight of a single-engine fighter if modeled to the same scale. In other words, if the fighter weighs in at, say, 12 to 15 lb., a comparable bomber would come out at about 72 to 90 lb.

The letter states: "One may ask: why make an exception in weight from the safety standpoint? For those who have seen aircraft flown of the example made above, the answer may be easy. Such aircraft fly relatively slowly and are very stable aerodynamically—as would be expected when comparing the performance of its full-size counterpart. This type of model also performs very little in the way of serious acrobatic maneuvers, which reduces probability of risk significantly during flight."

"If we start emphasizing the engine displacement limit for such models instead of the present limiting weight, we have really placed a significant control on the kinetic energy achieved during flight, since aircraft above 55 lb. would be forced into a slower velocity attitude."

The letter concludes with the following statement: "The Scale modeling community needs the opportunity to use .60- or .90-size engines with corresponding size and weight airframe to model four-engine aircraft and achieve what any Scale modeler is striving for: fidelity to scale."

In a nutshell, it seems that we should consider that last paragraph and ask ourselves the question: "Does the scale modeling community need to use .60- or .90-size engines on multi-engine aircraft?" Bear in mind that, unlike the IMAA proposal, Kent is not suggesting that the engine displacement limit be increased.

The last item regarding model size that the Council referred to the AMA Safety Committee was the rules change proposal submitted by Bill Northrop. Bill's proposal (Gen-84-9) was published in the December 1982 issue of MA (page 114) and would add another paragraph to Section 4, General, on page 7 of the current rule book. This paragraph would state:

"4.3 Weight Limit. Model aircraft weighing in excess of the current maximum amount specified in any AMA competition category shall not be permitted to fly in AMA-sanctioned activities, or in any AMA-insured activities, or at AMA-insured flying sites."

At the present time, RC Giant Scale, Section 53.B on page 83 of the rule book, permits models up to 40 lb. weight, which is the maximum permitted by any competition category. So, unless the Giant Scale weight limit is raised to 55 lb., there is a conflict between Bill's proposal and the Council-established weight limit. Since no proposal was submitted to increase the Giant Scale weight limit, the Council has referred the conflict to the Safety Committee for resolution. It is proper to note here that the AMA Safety Code weight limit is the factor which determines whether a model is covered by AMA insurance—not the competition rules.

All comments that we receive which address any or all of these three items concerning maximum model size will be passed on to the other members of the AMA Safety Committee. We suggest that anyone wishing to comment do so promptly. This column is being written at the end of October, but you will not see it until December. Pro or con, we would like to have your input.

Have a safe month.

John D. Preston 7102 Elvira Ct. Falls Church, VA 22042.

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