Safety Comes First - 2008/08
Dave Gee | [email protected]
The sudden attraction to magnets: a heated positive-and-negative debate
Look at the two photos of Don Butman's immaculate P-40. This was a Guillow's kit, mind you. He is almost finished building it, with only the propeller installation to go.
The whole model comes apart easily for storage or crashing, and it is held together with embedded magnets. Even the CO2 motor is held in place magnetically.
Don has been using rare-earth magnets in many of his models lately. They are now available in many sizes and are very powerful. Small ones are strong enough to hold a wing or light-duty motor mount. This means no more latches or exposed rubber bands.
This particular model is in the safety column because of the unusual problem Don had with the magnets that hold the wing in place. They held with great force when he installed them—so much so that he put a layer of covering over them to increase the distance a bit.
When the iron-on material was in place, Don was surprised to find that the magnets were holding with much less force than before. He cut the magnet faces clear, and there was still so little attraction that he added a wing peg for security.
I've gotten into the habit of using these little magnets in my models, despite the fact that I can't build 'em as pretty as Don can. I never use iron-on covering and I've never had a problem with weakening hold.
My suspicion is that the hot iron was the culprit. I know that high temperature can demagnetize a magnet, and that is exactly what these were exposed to.
Perhaps there is something else going on, but this story is presented as a warning to those who use rare-earth magnets, in actuators or to hold models together, and iron-on covering. Watch the temperature or install the magnets after the covering to keep things clinging as they should.
Frequency boards, impounds, and spectrum identification
B. R. McLean and I corresponded about the issue of frequency boards and impounds as related to "old-fashioned" radios that require controlled channels and newfangled systems that are not subject to interference. There are some differences in opinion on the subject. He had an interesting suggestion and I promised I would mention it, so here goes.
The problem is that a new or absentminded flier can get confused about which radios can and cannot shoot down other models and possibly turn on an older system by mistake—crash! Other pilots are frustrated by fields that keep spread-spectrum systems under some sort of frequency-control policy in this time of transition. Mr. McLean suggested using special identification flags on 2.4 GHz transmitters that identify them as not requiring a frequency pin. He showed me a ribbon that read "Spectrum Radio" and can be attached to the stub antenna. People have had different reactions to this concept. What do you think? Write to me via postal mail or send e-mail to the address in the column header. I'd like to hear about your close calls too. They make great reading and save others from harm.
Propeller injury: a reader's close call
I have a story about an RC pilot who shall remain anonymous, although you might be able to recognize him by his bandages. I received a forwarded message that read:
"While working on the engine for my Aeromaster last Sunday I tried to stop the propeller with my right hand. I broke two fingers and my thumb. My thumb required a skin graft because so much was removed by the propeller. I must have 100 stitches in my index finger alone.
"I had the plane tied off like I always do. When it first started it was held back just fine. When I killed the engine, the plane rolled backwards about 5–7 inches down a small incline. I did not notice this and must have moved closer to it to restart the engine. Well, it jumped forward and startled me, so rather than falling backwards I reached forward. Good thing it was a wood blade and not carbon fiber; otherwise I am sure I would have lost my thumb and index finger.
"Lesson learned? Always pull the plane against the restraint prior to starting. Share this with anyone you want. Maybe a reminder of the dangers will be good for us all."
Commentary from Don Lowe
Don Lowe offered these comments about the incident:
"People get hurt all the time because of the lack of secure restraint on starting or an inattention to where the propeller is. Guys unthinkingly reach through a whirling prop to reach the mixture control, etc. All we can do is bring these dangers to their attention from time to time.
"A lash restraint such as the one in this report is the least desirable because of the probability of an occurrence such as this. Have a buddy hold it for you or block it in a fashion that prevents motion fore or aft.
"I have seen guys start without restraint at all counting on their quick reaction on the throttle, and I have seen guys severely slashed and rushed to emergency because of this. That propeller is dangerous—even those on electric models."
Don has many years of experience, and his take on this is exactly right. Use a helper or a starting structure when available. If you have to use a tie-down, remember this story and don't let it happen to you!
Solar charger at the San Fernando Valley RC Flyers field house
A while back I printed a photo of a solar charger that the Los Angeles–area San Fernando Valley RC Flyers club built into its field house. The setup has panels on the roof that charge storage batteries that, in turn, can recharge flight packs on models.
These modelers even built a neat shelf to hold the batteries out in the open while the juice flows. Many pilots can use the system simultaneously.
I got many requests for details about this environmentally friendly setup. The club members have kindly furnished a drawing of how they laid out the components. It is not a full schematic. You will need some electrical know-how to build your own rig, but the parts are readily available.
I understand that the club members have expanded the system to charge even more airplanes and to power a grinder in their workshop—all without paying a dime to the electric company.
Off-Topic Rant: online speech, message boards, and AMA involvement
Strap yourselves in. I have a point to make, but I'm taking the long way round.
I recently visited Boston (to promote our hobby for the AMA) and was thrilled and humbled to visit places where men conceived and fought for the rights that we enjoy today. Take freedom of speech, for example. We can write and publish whatever we please (at least I can until the day MA Editor Michael Ramsey finally reads my column), for good or ill.
The Internet is the ultimate expression of this liberty, and thousands of AMA members communicate at the speed of light using chat rooms and online bulletin boards. I get lots of column material from friends I've never actually met, along with jokes, advice, and spam ads for miracle creams.
However, certain problems arise when we have unfettered, anonymous electronic freedom of speech. Human nature tends to drag uncensored chat rooms down a muddy path of off-topic insult messages that make political campaigns look like pillow fights.
We modelers are not immune to this. The very nature of our hobby tends to make us arrogant, since aeromodelers are in total command of every aspect of their personal fleets of flying machines.
I lurk and post on a couple of popular message boards. Sometimes it's hard to follow a topic thread through all the sourpuss "flame" messages. I recently saw a post that asked what a Web site visitor might think of modelers after reading a string of rude messages.
A common feature of such posts is to gripe about some issue by blaming a club or AMA leadership. No solutions, no discussion, no ideas, just some vitriol and name-calling. Some of the e-mail I get is like that, and I don't even know how to respond.
Thankfully, most messages are from MA readers who have given some thought to a problem and have a bright idea or insight to share. Some of these messages end up here in print, and some others are brought up at AMA meetings or are otherwise used to improve our hobby.
I'm just an AMA volunteer, but I pay attention to the opinions of somebody I see helping out at some flying event. An anonymous message insulting some official or department? Not so much!
This all comes up because of some business I saw conducted at the AMA Safety Committee meeting. Decisions were made in part on information and opinions that came through e-mail messages and online posts. AMA members who didn't even attend the meeting ended up greatly affecting things and helped make the correct choices. Guess which kind of e-mail and posts did not play a part?
If you want to change things for the better, there are ways to do it and ways to waste your time. The AMA staff has put out a call for members who want to play a more active part in the advancement of the organization and of aeromodeling. Take them up on it!
Sources / Contact
Dave Gee Box 7081 Van Nuys, CA 91409
Transcribed from original scans by AI. Minor OCR errors may remain.
