July ’08 Ken’s Pen

It’s hot. So what else is new? $5 Gasoline? $20 fuel? 2.4? That’s all old stuff! Well not really but it’s just part of the ongoing changing scene at the field that we see over time. The new 2.4 GHz systems are really taking hold. I haven’t heard a complaint about one failing in months. A recent AMA magazine event article said that they had 49 RC models in the air at once. All on 2.4. Apparently all operated trouble free. So when nobody else is on your “channel” (because you don’t have your own channel (s) on 2.4) how are you going to blame your recent crash on interference? Is that part of the changing scene too?

Hi! By the way, really excellent reading is the July article in the AMA magazine about the Airtronics 2.4 system. It will really help in understanding all of the 2.4′s, even the other brands. Read it if you want to understand why I can say you don’t have your own channel on 2.4!

Part of the long term changing scene of ARF’s and the routine fact that every one that I’ve looked at is built pretty darn straight and warp free. After a while we take it for granted. You put a new one in the air and all it needs is a click or two. All models are straight, right? Uh- Huh! ARF’s assemblers these days don’t even need to own a straight edge. Or a Square, when they really should have several! The pre -fabricated parts are usually fool proof to the most extent. Neat! The bad part is, without the tool, how are you going to verify a model is straight? And why know what parts should be aligned to one another? I often used something common as a square, like a piece of cardboard backing off a writing pad. Stuff like that is everywhere and easy to use so there’s no need to run down to buy another tool.

On a car we all know that the wheels must all be aligned for minimum wear and drag on the tires. Aerodynamic Drag is extremely important in a model too. Most is inherent in a design. Some is induced by surfaces being “crooked” requiring an opposite surface offsetting when they should or could be straight. That’s where the tools come in. Build it straight! ARF’s are fine but there are a few of us who still build. That’s when the straight edge and square stand out. You get used to ARF’s being straight, so for kit builders all you have to do is stick it together. UhHuh. We had a recent case at the field of a nice looking finished model. But the kit apparently was an old one and the die cut lite ply wood in it had developed unnoticed warps. Only upon final assembly was it noticed. Noticed? Well, actually the warps stood out like sore thumbs. Bad. Sad too. It could have been caught early with simple tools.

After Tai’s A123 Lithium battery article I’ve been following the A123 news. The following comment pertains to everything mfg in China and A123′s are made there too. A company in China called CBAK is making the cells for A123 and building a huge new plant. Prices may follow, I hope. Quote; “CBAK’s main competitors are Japanese and South Korean, both of which have substantially higher labor costs. The average wage in Japan is $2,700 a month and $1,500 a month in South Korea. But the average salary for a CBAK factory worker is around $160 a month. Hmmmm. How long can that last?

That’s a 10 to 1 labor cost advantage over the nearest low cost labor! No wonder ARF’s are cheap here! How long can that last too!

A123 cells as of today are apparently the rechargeable battery for the future. But they have some not so good aspects too. Size and weight for a given capacity are obvious. Since the type is recent, how long after coming off the production line will they last? All cells deteriorate with time. Some Ni-Cads hold up really well. Some! I’ve seen 10 year old packs still hold a charge. Maybe not full capacity, but a charge. A123 has only been producing cells for 3 years or so and just recently in volume. How are they going to hold up over time? We will find out! You can easily keep up with the A123 news too. Set up Google “Alerts” and they send an Email with links to any news that is published. Neat!

Like a lot of us, my eyes still glaze over when I read about brushless electric motor specifications. Maybe we can talk Tai into trying to clarify the situation. He seems to have a pretty good understanding. First there’s the motor brand name, then the in-house part number. Does its number have any relationship to its abilities? Like a “40″ alcohol motor is always a .40 Cubic Inch. Or a “40″ gasoline motor is Cubic Centimeters.

By the way, converting CI to CC in easy. A standard common size fuel motor is a .61 CI – or 10 CC. So a 40 CC motor is .61 times 40 or 2.44 CI. So the next time you hear that a new model is running a gas “75″, multiply in your head times .61 for a conversion to Inches. Easy, right? I’ll have the answer next month – I hope!

Actually I would round off the numbers. .61 to 6 and 75 to 7. Six times seven = about 4.2CI rounded off! Close enough but if you are pickie, add 6 more times the remaining 5 from rounding off. Six times Five = 30 but we left off a decimal before the 6. Stick it in and we have 3. Plus the 42. 75 CC = 4.5CI! Ummm. I forgot the .1! Buy a calculator!

73 (Best Regards)
Ken Meade WA6IVD