Archive for April, 2005

Camping on the playa?

A playa is the bottom of a dried up lake. In the Nevada Great Basin, these are often sinks or places between the mountains where water can flow in but not flow out. This means the runoff from surrounding mountains brings material and minerals that build up on the playa. The result can be a salty bed of rocks and sand many thousands of feet deep. It is very flat and can be a very large flat area with only the most hardy of plants and animals.

The playa does not extend an enticing invitation. What will get your attention on first arrival is the sand, the hazardous driving surface, the wind, the bugs, the dirt, the sun, the scratchy bushes, the stickers and thorns, the monotony.

It is after you have camp set and can sit back and relax that you can begin to see what the real invitation is all about. The quiet and solitude that creeps in is only buttressed by the noise of the wind. The vistas begin to be noticed causing you to reach for the binoculars because you realize the snow on the mountains are miles away and those ants on the horizon are cars and trucks on the main road. You can watch the shadows of the clouds chase across the mountain slopes in the distance.

If the sun and the wind and whatnot is getting to be a bit too much, you can retreat to your RV and look out the window and listen and feel the wind as you recover from a bit too much nature.

To see a photo gallery of a recent outing on the playa below the Lahonton Dam on the Carson River, go to An Airstream rally on the playa. To learn more about playa and desert geology and features, check out these links.

Digital Resources for Managing Wetlands – tries to figure out what we mean by “playa” and shows some nice pictures of various examples.

California Desert dot Gov – Your gateway to desert recreation describes a bit of the history and features found in desert areas.

steenssite geology describes the Alvord Desert, a 12 by 7 mile playa or dry lake bed created over 24 million years ago when Steens Mountain lifted. This playa is on the northern edge of Sierra Nevada Airstreams territory.

Pinyon Design-Lemmon Valley Marsh & Playa Master Plan Excerpts is about the plan for a bird watching area near Reno. See the photo gallery.

Theme Camp Ideas is a retrospective for future planning by Burning Man participants. This labor day event is a $5 million, 30,000 people event held on the playa north of Gerlach. The web page might provide some ideas about what people can do on a large, very large, flat area without even any plants to examine.

desertgeology has nice pictures and descriptions of land features you can find in and near the playa.

Playa Lakes, Links for Palaeobotanists is a place to start if you are into some serious research about what it was like for plants way back when the playa first formed.

Faulted Structures — The Slackpacker’s Geology Primer provides pictures and descriptions of some of the landscape features you can see near the playa.

A Look at the Playa is about why these dry lake beds occur. They also have a link to the rocket society which often does a launch party of very large amateur rockets on the Black Rock shortly after the Burning Man people have left.

Get out and see for yourself! Feel the playa intrude on your being. Get out and experience a part of the Nevada Great Basin that has its own, rather hidden, rewards.

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Understanding load leveling

Without a load leveling hitch, a tow vehicle may be ‘squirrely’ because the steering wheels are being lifted off the road. The headlights may also be lifted to shine into the eyes of oncoming drivers. The weight effects of the trailer tounge may also cause the rear axle to be overloaded.

When you hitch a trailer to a car it is like putting a weight on a see-saw. The trailer tounge pushes down on the rear bumper, the rear axle acts like a fulcrum, and the front of the car lifts. If the rear axle to bumper distance was long enough (the lever arm) and the trailer heavy enough, it is even possible to lift the front wheels right off the ground!

A load leveling hitch works against this leverage by stiffening the hitch point. If the bumper doesn’t go down, the front of the car can’t go up. The mechanism adds what engineers call torque or bending moments to the hitch. This is like having very strong hands grabbing the hitch on either side of the trailer ball and twisting each side to force the ball upwards.

There are four places of connection to make this twisting. These are two pairs (two hands) of connections that each provide leverage that generates torque. One hand is represented by the ball mount, shank, and receiver to provide torque to the tow vehicle. The other is defined by the ends of the spring bars at the ball mount and the attachment to the trailer A frame. But all this can be boiled down to two points at the spring bar connection in the final analysis. The spring bars and hitch assembly transfer the forces out to the truck and trailer.

Spring bars are used to provide some elasticity to the hitch stiffening. This is done for the same reason you have springs on your car wheels. Like springs without shocks, you can get some bouncing if the road bumps the rig just right. This bouncing is called porpoising.

The model is that of a loaded beam and how it resists bending. The load leveling hitch developes torque at the ball mount where the trailer tongue load is located. The twist is conveyed to the tow vehicle to lift its rear via the shank and receiver. The twist is conveyed to the trailer via the spring bars to lift its tonque. This twist is accompished by a force acting over a distance which is normally known as torque.

The key is how the spring bars are attached to the ball mount. The ball mount, shank, and receiver are the ‘fixed’ parts. The spring bars have a mount that is rigidly attached to the ball mount. That is rigid in terms of up and down but quite flexible in terms of side to side. So the mount usually has several inches of steel up and down and a rotating mechanism for side to side – like a very strong hinge.

What you really have is the same kind of considerations you would have for a beam supported on each end with a load in the middle. How does it keep from breaking under load? What makes it stiff and resists bending? Same thing with a hitch, just a slightly different mechanism.

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Did you know there are two kinds of feet?

Ed McKay describes some fallout in the conversion from older measuring systems to newer ones in the mapping and survey fields.

First, remember this rule: There is only one meter, BUT, there are two types of feet. The two types of feet are:

1. The U.S. Survey Foot: It is defined as: 1 meter = 39.37 inches. If you divide 39.37 by 12 (12 inches per foot), you get the conversion factor: 1 meter = 3.280833333… U.S. Survey Feet.

2. The International Foot: It is defined as: 1 inch = 2.54 centimeters. If you convert this to meters and feet, you get the conversion factor: 1 International Foot = 0.3048 meters.

These two conversion factors produce results that differ by 2 parts per million; hence for most practical work it does not make any difference to the average surveyor which one is used since they usually do not encounter distances this large. For example, converting a distance of 304,800 meters (about 1,000,000 feet) to feet using the two conversion
factors, these are the results:

304,800 meters = 999,998.000 U.S. Survey Feet
304,800 meters = 1,000,000.000 International Feet

A difference of 2 feet in 1 million feet.

It appears that different states use different feet. Most folks are trending towards metric via the international foot. But the National Geodetic Survey uses survey feet when it specifies elevation.

We publish elevations in meters to the nearest millimeter (3 decimal places) and in feet to hundreds of feet (2 decimal places). For elevations above 5,000 feet (1,524 meters), the conversion factor will change the foot value by one in the second place.

So the heights of passes and mountain peaks on the maps might be off a bit from what you might think they ought to be. Now, the real question is how on earth they can measure things on land to that degree of accuracy?

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Seeing behind you

Mirrors are so old fashioned. A video camera can give you a better view of what is behind you. But there are things to consider. Where you do place the monitor and what kind of monitor do you use? Where do you place the camera? Color of black and white? Can you reverse the image so it is just like looking in a mirror?

RVCams Backup Cameras and Rear View Systems

Welcome to www.mymobilevision.com, your on-line mobile camera superstore.

XCam2: Wireless Home Surveillance Video Camera!

RV Rear View Systems Page 1

A backup camera is no magic bullet. You still need to take care and learn about how your rig behaves. See backing up for additional ideas and links.

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Hydrometers, ugh!

Hydrometers are the time honored means to measure wet cell battery state of charge. They compare density (weight per volume) to water by how things float. Battery acid in full strength has a specific gravity of 1.84 (times heavier than water) but only 1.277 in a fully charged battery (because it is diluted with water).

The specific gravity is useful because a battery converts acid to water in the process of making electricity and vice versa when being recharged. It is easy to make a hydrometer sensitive enough to measure the reduced density as the concentration of acid is reduced. This allows you to tell the state of charge of each cell in the battery.

The advent of digital voltmeters provides a better means for RVer’s to keep track of battery condition. A hydrometer a good way to contaminate cells, spill acid on things, and generally cause havok. Proper use of a hydrometer requires proper safety equipment (goggles, apron, glove, working space, ventilation) and appropriate emergency supplies (eye wash, neutralizing solution, observer) close to hand. Proper hydrometer use requires care, and temperature correcting. See the Trojan site for how to test your batteries.

For most small RV battery situations, a good voltage reading (to a tenth of a volt) will tell you all you really need to know, be safer to do, and be a lot more convenient. This is especially true when watching the voltage during your campout as you can see how fast your battery voltage drops.

The much more expensive amp-hour meters actually measure electricity going into and out of your battery. These will give you a much more accurate indicator of the state of your battery, even better than a hydrometer, but they are expensive and not really cost effective for most RV needs. The trimetric and link10 are popular models. Cruzpro is another.

With your voltmeter, you can check for the basics:

  • A float charging voltage over 13v and under 14v is OK. The closer to 14v the more care you to take to keep an eye on water levels, depending on how cold the battery is.
  • In use, the battery voltage should be over 12v or it needs charging.
  • In storage it should remain above 12.2 or so.
  • In measuring batteries, you’ve really got two issues to deal with. One is state of charge and the other is battery capacity. Hydrometers only tell you state of charge which can be determined close enough for most RV purposes by voltage under load. This is only a real concern when you have to stop using it because you don’t have a charge handy. Otherwise – put a maintainer and charger on the battery and keep it properly charged for best life.

    The other issue is that battery capacity slowly degrades as the battery ages and is best determined by watching how fast the voltage drops over time in typical use conditions. If it doesn’t last anywhere near as long as it used to, then it is time to replace the batteries in you bank.

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    Carson Sertoma chili cookoff this weekend

    Topaz-Carson Valley Chili Cookoff & Craft Fair Sat Apr 16th – Sun Apr 17th at th Carson Valley Inn, Minden on US 395

    CS sanctioned chili cookoff & open craft fair (no food/beverage vendors). Event previously held at Topaz Lake NV, but we ran out of room and the Carson Valley Inn offers at least twice the space and will draw more spectators. Spaces are 10X10 with 2′ between. Area is a 1 1/2 acre gravel parking lot behind the RV Park.

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    Why aluminum cans are shaped the way they are.

    Soda Pop Science in USA Today April 12 describes why aluminum beverage cans have the shape they do.

    The title also illustrates a need for a bit better education about science and technology in the media. This is about Soda Pop Engineering – not science.

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    Politics – you can’t get away

    RV parking needs common-sense rules is an opinion of the Nevada Appeal.

    Unfortunately, not everybody can agree on what’s reasonable. That’s why City Hall has to come up with rules for handling nuisances, whether it be barking dogs, frequent garage sales or RV parking.

    They expect common sense and dialog to solve some people’s problems with irritating neighbors?

    Then there is the pending state law. Escapees has quite a discussion going on SB412 to Ban overnight parking statewide.

    Then there is the DMV, property taxes – it can make you paranoid if you aren’t careful.

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    internet access with your cell phone

    Odds are that you won’t be able to get cell phone service in many areas of the Great Basin. If you are along the freeway or near a decent town, it might be a way to keep in touch while you are trying to get away from it all. But when you get out to some of the more interesting areas, you should not expect to be able to depend up phone service. Here are some links to peruse for ideas about cell phone service and coverage areas.

    HOW-TO: Use your CDMA cellphone as a USB modem – Engadget – www.engadget.com – a lot of cell phones have a connection you can use to make them look like a modem to a computer. Here is a step by step guide to get a Windows machine connected.

    Reno Area Wireless Information & Cellular Guide – Cell site location maps, pictures, carrier evaluations & more – if you want to know about coverage in the Reno area and what people think of Reno area cell service providers, this site provides extensive coverage.

    Preferred Roaming List – If you don’t know what a PRL is, then check out this page. You need to be up on these lists and how to update your cell phone if you travel a lot and want to take best advantage of your cell plan’s roaming services. A Verizon FAQ about this is available. Open Roads Forum : Verizon Wireless Users – update your roaming, new PRL released 2/21/05 a discussion about PRL updating on RV.NET

    Coverage Locator – Find out where you can use a Verizon phone and what kind of service you can expect.

    broadband » Cellphones, providers, and plans – a discussion group about cell phone plans and providers.

    CellSocket – whpwireless – a nifty gadget for some cell phones that connects the phone to a power supply, external antenna and then use a standard telephone to make and receive cell calls.

    For news related to cell phones, check out Mountain Wireless.

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    Boxes to hold in and secure computer applications

    If you are one of those folks stuck in a Microsoft world, then you are familiar with the need for firewalls, virus scanners, and other methods to fend off scams and harassment. Here is another approach that appears to have promise. It is similar to Java in setting up a ‘sandbox.’ The Microsoft web browser and email client are run inside the sandbox. When you are done browsing and messaging, then you clean the sandbox and close it up. This terminates any programs, such as virus programs, that may have been downloaded and resets any system settings that may have been changed. When you close down your internet session, your system should be back to just like it was before you opened it.

    GreenBorder Makes Microsoft IE and Outlook Safe to Use

    The program has a free ‘personal’ edition to try to get you to upgrade to purchasing the ‘professional’ version with extra security features. It might just be an additional layer of protection to augment your anti-malware scanning software and firewall software and good internet user practice to help keep your system your own.

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    Tire Deterioration

    This was posted on Escapees where Doug provides a good summary of what makes tires deteriorate.

    In the old days, we simply said, “It wore out”. These days we look more deeply into the hows and whys. With tires, particularly RV tires, there are some specific chemical changes that occur within the tire as time goes on that cause the tire to “deteriorate”.

    Tires are made of a rubber polymer, Sulfur, and Carbon. These chemicals are combined at high heat (vulcanization) to form divalent chemical bonds between the substances to give the desired characteristics of elasticity, flexibility, durability, and strength. There are also other additives whose purpose is to slow down tire deterioration. There are also “belts” of synthetic material and/or steel wires to give additional strength.

    Heat (Under inflation) Some of the factors which cause deterioration have been known for some time. And some factors are currently under investigation and are still in the “theory stage”. One of the most significant factors in tire deterioration is under inflation. This puts stress on the rubber in several ways, the most important being overheating. This was seen in the Ford Explorer-Firestone tire separation phenomenon which we remember from a few years ago. As all of us RVers know, heavier loading of the vehicle requires higher tire pressures, or said another way, overloading an already under inflated tire dramatically compounds the problem. And overloading a properly inflated tire beyond it’s maximum weight rating is probably the most common cause for RV tire failure, since weights by the RV Safety Foundation show 60% of RVs to be overloaded on at least one corner.

    Ultraviolet light Another reported factor in tire deterioration is ultraviolet light. This comes from the sun and its energy causes chemical changes within the rubber. It is not entirely clear to me exactly how important UV damage is, but some of us try to cover our tires when parked anyway. One of the additives to tires is a wax that blocks UV light. But to be effective, the compound must work it’s way to the surface of the sidewall of the tire. This happens when the sidewall is flexed and heated during normal driving. But it does not get replenished to the surface when the tire is sitting still. Since only a small percentage of RVs I see have tire covers, there are a large number of outside dual tires with UV damage. This should result in a higher frequency of outside dual tire failure. However, it is reported that the inside dual fails more often then the outside (probably because it carries more weight due to road crowning).

    Rusting Another form of deterioration that occurs is rusting of the steel belts. To get rust, we must have iron (steel), oxygen, and water. Now it has been claimed for some time that the water gets in from outside. That small cracks or cuts or damage to the rubber will allow water to be absorbed through the rubber into the steel belts to start the rusting process. Most of us are aware of this concept in the form of a recommendation that we use some type of a “vapor barrier” under all our tires. I had one tire manufacturer tell me that asphalt is bad and cement is OK, and the next one tell me just the opposite. I have always had some trouble with the concept of the tire sucking up water from the ground, but my opinion and the facts may not be the same. Apparently the move is to coat the steel wires with copper to prevent rusting (one report) or brass to improve rubber adherence to the belts and prevent tread separation (another source).

    But another theory is that the water comes from inside the tire. Air is made up essentially of 20% oxygen, 80% Nitrogen, a minute amount of other gases, plus a bit of water vapor (depending on where you live, it may be more or less). Now to fill a tire, you need air under pressure. An air compressor takes a large volume of air, and compresses it into a small volume. This means you end up with a large amount of water vapor in the air that you put into your tires. And that water vapor is under 80 (or more) pounds per square inch of pressure. Although the liner of the tire is designed to prevent things from being pushed through it into the rubber, the liner does not work perfectly, nor forever. So the current theory is that the water responsible for rusting the steel belts comes from the compressed air.

    Oxidation The chemical changes that occur to the rubber polymer during the manufacturing process produces a number of bivalent chemical bonds between the molecules. The primary change that occurs during deterioration of a tire is the creation of more chemical bonds between the molecules as time goes on, a process called oxidation. This is a bad thing because then the rubber becomes stiff (not flexible) and hard, which will lead to tread separation, blowouts and disintegration. Keep in mind that the speed of any chemical reaction doubles with a rise in temperature of 10 degrees Centigrade (approximately 18 degrees Fahrenheit). The tire does not care whether the temperature rise is the result of under inflation/overloading or hot outdoor weather.

    Oxygen is a relatively weak chemical oxidant. It will combine with other substances (such as iron, to form rust), but it happens relatively slowly. Ozone is a strong chemical oxidant. It is formed in the atmosphere by lightening (or electric motors, like those on air compressors) and UV radiation. It’s molecule has 3 atoms of oxygen as opposed to the usual 2 atoms of ordinary oxygen. So the current thinking is that the presence of ozone (and other oxidants) inside and to a lesser extent outside, the tire may be the prime culprit in tire deterioration (the making of excessive bonds between rubber polymer molecules). As with water vapor, it seems more likely for ozone and other oxidants to be forced into the tire from the inside (high pressure) than to be “invading” the tire from the outside. But “seems more likely” may not equal a fact.

    So during manufacturing, antiozonants and antioxidant chemical compounds are added. These appear to slow the oxidative process. But they get used up in the process of neutralizing the oxidants. They also seem to work better when the tire is flexed and heated during use.

    Nitrogen The next step in the attempts to slow deterioration was the introduction of pure Nitrogen for inflation of tires. This has become more practical with the advent of modern membrane technology, whereby air is taken in and passed through a semipermeable membrane where the oxygen, ozone and water vapor escape out through the membrane, and nearly pure nitrogen goes into the tank. Nitrogen inflation has been used for many years in airplanes, race cars, bicycle racing, military and fire vehicles, and a few trucking firms. Less pressure change during a race (better handling), cooler running tires, longer tire life and fewer sudden tire failure result. One trucking company who runs over 2 million miles a day averaged 35 failures per day. After inflating with Nitrogen, they are having 5 failures per day, three quarters of which are road hazard damages.

    Nitrogen is totally inert, that is it is very reluctant to get involved in chemical reactions. With nitrogen inflation there is no oxygen, ozone or water vapor inside the tire. Probably the biggest benefit for the trucking industry is that nitrogen diffuses through the tire more slowly than oxygen. This means that tires hold their pressure longer (although I almost never loose air from my tires). So there is less likely to be under inflation with nitrogen. Tires also run cooler with nitrogen, and the rise in tire pressure after driving is less (air filled tires went from 95 to 120 psi, Nitrogen tires went from 95 to 100). Most of the temperature and pressure rises are felt to be caused by the water vapor. A number tire dealers, truck stops, Wal-Marts and Costcos around the country are providing nitrogen inflation. Nitrogen is not recommended for old tires, but should be considered for new ones (or a few months old??). In an urgent situation you can add air to a nitrogen filled tire and replace the Nitrogen when you get home.

    Although it is attractive to have our RV tires hold their pressure longer, the biggest potential for RV tires inflated with nitrogen is they appear to undergo a more gradual oxidation-deterioration, based on the trucking reports. Fewer sudden events (blowouts) seem to occur. If this is substantiated on large RV (and truck) trials, our tires may stay softer, more flexible, stronger, and with less rusting. Hopefully we will be able to safely run for longer periods before replacing.

    Tires start to deteriorate as soon as they are made. Look on your sidewall to see the week and year your tires were produced. Thicker tires (truck) tend to last longer than passenger tires in part because it takes longer for the oxidant-bonding process to work through the tire. Truck tires also last longer because they are used every day and the regular flexing and heating is beneficial. The majority of experts feel that 5 years is the maximum time to run an RV tire. It may be that by using Nitrogen, we will be able to significantly slow the deterioration process, reduce the risk of sudden tire failure and extend tire life another year or two… or more?

    Recommendations

    • Look at your tires for tread wear and sidewall defects
    • Weigh your RV on all four corners
    • Get a weight/tire pressure chart from your tire manufacturer
    • Get the maximum speed rating of your tires from the manufacturer (Goodyear = 75mph)
    • Read the maximum cold tire pressure on the sidewall
    • Inflate your tires to the proper pressure. Check pressure frequently.
    • Increase tire pressure when you are loaded.
    • Strongly consider a remote tire pressure monitoring device (toad too)
    • Don’t allow yourself to overload (weigh frequently)
    • Keep track of your date of manufacture. Don’t go over 5 years
    • Use sun protection and vapor barriers to make yourself feel better
    • If using your own compressor, empty the water frequently
    • If you have a choice, fill your tires on low humidity days
    • Try to find a shop that uses a “dryer” on their air compressor
    • Give serious consideration to nitrogen inflation with new tires
    • Drive your RV

    When I graduated, our professor announced, “We have some bad news; Half of what we have taught you will be proven to be incorrect. We have some really bad news; We are unable to tell you which half.” That’s how I feel about this attempt to learn about the subject of tire deterioration. I would sincerely appreciate the input and correction from any reader who knows which half I have messed up.

    doug
    doug@rexhallitps.com

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    Dew point and humidity

    How Humid Is It? Simple Conversion Between Relative Humidity And Dew Point In Moist Air describes a simple rule of thumb for converting between dew point and humidity – when the humidity is above 50% (i.e. not for our high desert conditions). This is that there is 5% relative humdity change for every degree Celsius.

    if it is 30 °C outside, and the relative humidity is 75%, then the dew point temperature will be about 25 °C. It’s also easy to see how much could be gained from evaporative cooling – in this case, at most 5 degrees. “Further, by adjusting the relationship a little to account for the effects of temperature, it is also simple to use the relative humidity to compute the altitude of cumulus cloud bases without a calculator to a good approximation, usually within about 10%”, says Lawrence.

    In the first example, going from 75% to 100% is a change of 25% which means 5 degrees Celsius. In the second, you need to know that there is a temperature drop (the lapse rate) of about 6.5 degrees C for every 1000 meters.

    Another interesting article about what temperature, altitude, and humidity do to bullet trajectories is at Lilja Precision Rifle Barrels – Articles: Ballistic Effects of Altitude, Temperature and Humidity

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