Safety Comes First
John Preston 4025 Peppertree La., Silver Spring, MD 20906
This column addresses items of concern regarding safety aspects of model aviation activities. The content is the opinion of the author and does not necessarily represent the official position of the Academy of Model Aeronautics.
Plastic props — to ban or not to ban? Deer decoys, modelers, and the law
Accidents also happen at home. Not all injuries associated with our hobby occur at the flying field. I received two reports during March describing incidents that occurred in modelers' homes, and both required a trip to the hospital.
Rick Townsend — prop lodged in chest Rick Townsend, an Alexandria, Virginia modeler who flies with the Pohick Pilots club, called to describe how he ended up in the hospital after being struck in the chest by a prop thrown from a model.
Rick was in his backyard attempting to start and tune a .90-size two-stroke installed inverted in a Messerschmitt (Me 109). The scale spinner on this model is too large to accommodate the cone on an electric starter, so he uses a chicken stick to start the engine. The engine started and sounded normal, so Rick opened the throttle to full bore (estimated to be around 10,000 rpm). Moments later the engine went dead as it threw off the three-bladed glass-reinforced nylon prop. Rick was positioned in front of the model, and the errant prop struck and penetrated his chest. His wife heard him cry out when the prop hit him and immediately called 911. Realizing this was no minor event, Rick lay still on the ground until the rescue squad arrived and took him to the hospital.
Rick was fortunate: the prop did not break and did not penetrate anything vital—although it lodged very close to the heart. After removal, Rick was kept in the hospital for observation for two days; when he called me eight days after the accident he was already back at work. He said he didn't know whether to keep the prop as a souvenir or put it back on the Me 109 and fly. "I think if it were me, I'd keep the prop as a souvenir to remind me that my guardian angel might not always be looking out for me."
Emmett Fry — fiberglass dust leads to serious infection I learned of a second home accident by way of a letter from Little Rock, Arkansas modeler Emmett Fry. His letter read in part:
Your readers may be interested in a bizarre shop accident that has made me a born-again shop safety addict. It began on a Monday in mid-February. I dinged the back of my right hand on the corner of my desk. No problem. I wrapped a paper towel around it until it stopped bleeding.
On the following day, Tuesday, the ding was a little red and a little sore. By Wednesday, the back of my hand was swollen, angry red, and clearly infected. I poured a bit of hydrogen peroxide on it and spent the evening in my shop dressing down a fiberglass/epoxy cowl on my Dremel sander.
To shorten the story, on Saturday morning I was wheeled from the emergency room into surgery. By this time my right ring finger had become swollen, had a purple hue, and pounded in excruciating pain.
The orthopedic surgeon who operated on my finger said that if I'd waited eight more hours, I'd have lost the finger. Sixteen more hours and the hand would have had to come off at the wrist.
The prognosis was that fiberglass particles from that cowl had entered my body through that infected ding on the back of my hand, latched onto a streptococcus bacteria, headed down a vein to my ring finger, and settled in as cellulitis.
We all ding ourselves during the course of building model airplanes, but we manage to patch our wounds and muddle through. Props, knife blades, wire, soldering iron burns—we've suffered it all. But a minuscule piece of fiberglass dust?
Come on!
My bottom line is immediate first aid, gloves when working with fiberglass, and more attention to shop safety and cleanliness in general. I'm in therapy now, getting back the use of my hand. This letter is by hunt-and-peck.
In a follow-up letter Emmett sent a photo showing a cast on his right arm which he said he can remove from time to time. He now has about 60% hand use and estimates it will take six to ten months of therapy before his hand is back to normal.
I find it ironic that a simple ding on the hand resulted in serious problems for Emmett, while Rick, after having a prop lodge in his chest cavity, was back at work in just eight days. As I previously said, that guardian angel may not always be on duty.
Ban plastic props? The Society of Antique Modelers (SAM) has received a proposal to change its RC rules (Section 1, Paragraph 12) that, if adopted, would permit "only fixed-pitch, non-folding, two-bladed propellers made of natural wood, except for .051 and smaller engines, which may optionally use plastic or composite propeller materials."
This was brought to my attention by Martin Schindler of Vienna, Virginia, a SAM member. Marty enclosed a copy of the pages in Sam Speaks (September/October 1990) where the rules change and its rationale appeared. Marty asked why, since this appears to be a safety-related item, it wasn't proposed and adopted as part of the AMA Safety Code or contest rules.
Following is part of the lengthy rationale submitted with the rules change:
Rationale for the proposal: Intent is to reduce severity of propeller injuries. We averaged almost one trip to the hospital for every two major contests I attended last year. At the 1989 SAM Champs, one freshly bandaged victim leaving the emergency room met the next case walking in with his hand still wrapped in a bloody rag. For over two years I've taken an informal poll and find these injuries come overwhelmingly from plastic, as opposed to wooden, props.
A plastic prop does more damage than a wooden prop because:
- it's heavier and carries more kinetic energy at the same rpm;
- it's stronger and more likely to deliver its full momentum at impact because it won't shear off as a wooden prop will; and
- on impact with bone or tendon, the plastic prop is harder and will not crush and deform itself; it will slice, crush, and deform bone instead.
The rationale went on to discuss the physics of collisions between a hand and wood versus plastic props and showed that a plastic prop has about twice the momentum of a wood prop of similar size. The proposer concluded:
Okay, so why don't I just use wood props and let the rest of the world use whatever it wants? Couple of reasons:
- The plastic props are often a little more efficient, and we are talking about competition where people will use something less safe if it's necessary to keep up with the others.
- It isn't always the owner who gets hit; it's sometimes his timer, helper, or occasionally a bystander on, say, a "radio off" launch.
- In an extreme case, if a running engine hits someone around the head or neck, prop selection could make the difference in a possible fatality.
So much for the rationale. Sounds reasonable, right? Well, maybe. There is no question that a serious injury can result if you inadvertently put a finger or hand into the arc of a rotating plastic prop. On the other hand, isn't the same true for a wood prop?
If I step off the sidewalk into the path of a Lincoln Continental traveling at 45 mph, I am more likely to be seriously injured or killed than if I step into the path of a Honda Civic traveling at the same speed. Should we ban Lincolns?
This may sound as if I'm not in favor of the proposed SAM ban of plastic props. Not necessarily so, but I'm not convinced by the rationale that there are convincing grounds for such a ban.
For example, I don't question that the proposer has seen more injuries caused by plastic props than by wood props at SAM events. On the other hand, if plastic props are "a little more efficient," they may also be more commonly used at these events than wood props. Anecdotal data doesn't always give us the correct picture when assessing a hazard. I'd like to see some statistically valid data on the number of plastic versus wood props in use and compare this to data on injuries associated with each type. If most of the props now in use are plastic, it stands to reason that most injuries will be caused by plastic props.
At this point I do not have a firm opinion on whether the proposed ban of plastic props in SAM RC events is desirable. However, I would like to hear readers' opinions on this issue.
RC deer decoys
RC-activated deer decoys were the subject of a letter from Ed Hunter, secretary of the Amory (Mississippi) R/C Modelers. Since I am not a hunter, I had little idea what a "deer decoy" is supposed to do and why it would be operated by radio control. Unlike duck decoys that attract wild ducks, my guess is that a deer decoy is intended to attract deer—or perhaps to attract illegal hunters. Someone who knows hunting better may want to correct me.
Ed enclosed two letters he had written to the Mississippi Department of Wildlife, Fisheries, and Parks together with the response he finally received. It seems deer decoys, used in enforcement activities of Fish and Wildlife Service officers, were alleged to be operating on model-aircraft-only frequencies. If so, their operation would be illegal and could jeopardize the safety of the Amory R/C Modelers.
It took two letters from Ed before he got a response from the department, which stated: "The problem with Conservation Officers' using remote control transmitters on model aircraft frequencies has been discussed and the matter has been taken care of." We may never know the full facts, but it sounds as if the allegation of illegal operation may have had some truth.
The reason I'm including this topic in the Safety column is to warn others who operate RC models from flying fields in remote rural areas. There may be other sources of interference besides paging devices. Speaking of which, I hope you all read Bob Underwood's "A Note From the Technical Director" in the April 1991 issue of Model Aviation, and that you have had your old transmitter(s) narrow-banded.
FF92-14 rule change proposal (Catapult glider launches)
Another proposed rule change that may compromise the safety of an event is FF92-14, which would permit hand-held catapult launchers as well as the current fixed-pole variety. George Armstead Jr., a Connecticut modeler who participates in Catapult Glider events, believes this change could reduce safety.
George argues that with a fixed pole the contest director (CD) can establish the launch pole in a safe location. With hand-held launches the CD or assistants must constantly police the launches, which reduces the officials' time available to run other events and puts the official in an adversarial position with contestants. George also worries that it would be difficult for a CD to ensure hand-held launches comply with the FF Safety Code rule requiring "launching 100 feet downwind of spectators and automobiles."
I am not familiar with this event, but it appears the initial vote has approved hand-held launchers. If you are a Catapult Glider enthusiast, consider this possible rules change and make your opinion known to your FF Contest Board member.
Prison term for modeler — secure your model when transporting
If Emmett Fry thinks his shop accident was bizarre, he should read this account that appeared in a clipping from the Riverside, California Press-Enterprise, sent to me by Al Wolski.
A Norco, California modeler was transporting an RC model in the back of his Ford Bronco. Ahead of him a vehicle was stopped, preparing to make a left turn. Passing on the shoulder he came upon another car that was also attempting to pass the stopped car but was traveling slower than his vehicle. According to court documents, the modeler did not apply his brakes for fear of damaging the radio-controlled model airplane he had in his car. Instead, his car bumped the vehicle from behind. The driver lost control, swerved into oncoming traffic, and her car struck another head-on, killing the occupants, a 75-year-old man and his wife.
The modeler briefly lost control of his car and then drove away without stopping. A subsequent eyewitness described the modeler's vehicle, and it was later located outside his residence. The modeler was reported to have told investigating officers that he had not stopped because he thought he was not responsible for the accident. He had been talking on his cellular phone when the accident occurred and claims that he "was busy checking my model." The modeler pleaded guilty to a charge of "felony hit-and-run with injury and death" and was sentenced to two years in state prison.
I admit there have been times when I've hesitated briefly before applying my brakes because I was concerned about damaging unsecured objects (not models) in my car. But consider the forces involved.
A 0.5g deceleration will cause your passenger to give you the evil eye. On dry pavement with a good surface the maximum deceleration you can achieve, even with anti-lock brakes, is about 1g (32 ft/sec^2). By contrast, a deceleration of 50g or more could result from a head-on collision.
Would you rather subject your model to a force equal to its own weight (1g deceleration) or let a collision occur and subject your car, yourself, and your model to forces equal to 50 times their weights—and pay the repair bills as well?
The moral is obvious: always secure your model, or any other object you are transporting in your car (including passengers), so you don't have to worry about their well-being if you must brake hard for an emergency.
On that note, I wish you another safe month—safe in your home, in your car, and at the flying field.
Transcribed from original scans by AI. Minor OCR errors may remain.
