Question calibrating 400T Barometer

[+Michael]

Ok I went to calibrate the altimeter on the 400T today and had the accurate Current Barometer reading. It will not let me enter the second decimal place. I go to 29.9 and it would not let me enter the 7. The pressure was 29.97 at the time. Is this the same for everyone of is my wacky. I have 2.51 loaded.

 

Thanks.

[+StarBrand]

Did you try entering it in millibars instaed of inches?? Should be more accurate.

[+Michael]

It didnt give me that option

Inches was the only choice

that I saw

Edited May 28, 2008 by Michael

[+g-o-cashers]

It didnt give me that option

Inches was the only choice

that I saw

 

Setup->Units->Pressure->Millibars

 

GO$Rs

[+julianh]

Ok I went to calibrate the altimeter on the 400T today and had the accurate Current Barometer reading. It will not let me enter the second decimal place. I go to 29.9 and it would not let me enter the 7. The pressure was 29.97 at the time. Is this the same for everyone of is my wacky. I have 2.51 loaded.

 

Thanks.

Looks like another issue to raise on the Colorado wish list - only being able to calibrate to 0.1" Hg precision is pretty poor!

 

On my Summit HC, I can calibrate to 0.01 hPa / 0.01 mbar / 0.01" Hg. Note that calibrating in hPa / mbar is MUCH more precise than calibrating in inches Hg, because an interval of 0.01 is roughly 1 part in 100,000 in hPa or mbar (as a standard atmosphere is roughly 1,000 hPa / mbar), but is only one part in 3,000 in inches of mercury (because a standard atmosphere is roughly 30 inches of mercury).

 

Another good reason to switch to the metric system!

 

Note that the barometer display on my Summit HC only shows 4 digits, whatever units you select, but internally, it is carrying much higher precision than it displays. Also, even though the initial calibration in inches of Mercury is less precise, this should only affect the first few minutes of your records, if auto-calibration is turned on, because the auto-calibration routine will start to over-ride your initial calibration anyway.

 

Hope this helps!

[+Team CowboyPapa]

 

Another good reason to switch to the metric system!

 

What was the other one?

[Hertzog]

 

On my Summit HC, I can calibrate to 0.01 hPa / 0.01 mbar / 0.01" Hg. Note that calibrating in hPa / mbar is MUCH more precise than calibrating in inches Hg, because an interval of 0.01 is roughly 1 part in 100,000 in hPa or mbar (as a standard atmosphere is roughly 1,000 hPa / mbar), but is only one part in 3,000 in inches of mercury (because a standard atmosphere is roughly 30 inches of mercury).

 

 

On the 60CSx if you select the barometer or ambient pressure plot the data field at the bottom will display mbars to 0.1 mbar. One way to ekk out a little more accuracy, but I've decided it's impractical, since I generally want to see the ambient and barometric pressures and the elevation all at once when I'm looking that closely at things.

[+julianh]

 

Another good reason to switch to the metric system!

 

What was the other one?

OK - answer quickly, and no use of calculators:

 

How many inches in a mile?

 

How many ounces in a ton?

 

How many horsepower (or BTUs - you can select the unit of power of your choice!) does it take to lift a weight of one pound at a speed of 1 foot per second?

 

Equivalent questions in metric:

 

How many millimetres in a kilometre? A: 1,000,000

(Or if you prefer - How many centimetres in a kilometre? A: 100,000)

 

How many grams in a tonne? A: 1,000,000

 

How many watts to lift a weight of 1 newton at 1 metre per second? A: 1.000 W

 

And so on!

[+julianh]

 

On my Summit HC, I can calibrate to 0.01 hPa / 0.01 mbar / 0.01" Hg. Note that calibrating in hPa / mbar is MUCH more precise than calibrating in inches Hg, because an interval of 0.01 is roughly 1 part in 100,000 in hPa or mbar (as a standard atmosphere is roughly 1,000 hPa / mbar), but is only one part in 3,000 in inches of mercury (because a standard atmosphere is roughly 30 inches of mercury).

 

 

On the 60CSx if you select the barometer or ambient pressure plot the data field at the bottom will display mbars to 0.1 mbar. One way to ekk out a little more accuracy, but I've decided it's impractical, since I generally want to see the ambient and barometric pressures and the elevation all at once when I'm looking that closely at things.

Yes, you're right - turns out it works the same way on my Summit HC when I switch it to barometer plot mode. I never noticed that before (probably because I generally use it in altimeter mode, not barometer mode). Thanks for the tip!

 

The bottom full-width data field is wide enough to show 0.1 hPa / mbar increments when in barometer mode or ambient pressure mode, and you can set one of the top two narrower fields to be elevation, and the other one to be ambient pressure (when in barometer mode), or barometer pressure (when in ambient pressure mode), so you CAN have your cake and it eat too! (Although only the pressure in the full-width bottom window will show 0.1 hPa increments; whichever pressure you choose to show in the narrower top windows will only show 1 hPa increments.)

[+flattie]

 

On my Summit HC, I can calibrate to 0.01 hPa / 0.01 mbar / 0.01" Hg. Note that calibrating in hPa / mbar is MUCH more precise than calibrating in inches Hg, because an interval of 0.01 is roughly 1 part in 100,000 in hPa or mbar (as a standard atmosphere is roughly 1,000 hPa / mbar), but is only one part in 3,000 in inches of mercury (because a standard atmosphere is roughly 30 inches of mercury).

 

 

On the 60CSx if you select the barometer or ambient pressure plot the data field at the bottom will display mbars to 0.1 mbar. One way to ekk out a little more accuracy, but I've decided it's impractical, since I generally want to see the ambient and barometric pressures and the elevation all at once when I'm looking that closely at things.

 

I have a 400T, can someone tell me the different between plot barometric pressure or ambiant pressure. I use this function just to track differential of the current conditions, vs an hour ago. IE, i want to know if the barometer is rising or falling, to track the weather. This has confused me since the beginning and it doesn't tell you anything in the manual. Thanks

[+g-o-cashers]

I have a 400T, can someone tell me the different between plot barometric pressure or ambiant pressure. I use this function just to track differential of the current conditions, vs an hour ago. IE, i want to know if the barometer is rising or falling, to track the weather. This has confused me since the beginning and it doesn't tell you anything in the manual. Thanks

 

From Garmin's FAQ, I'm assuming this applies to the 400t as well.

 

GO$Rs

[+Team CowboyPapa]

 

OK - answer quickly, and no use of calculators:

 

Hey, that's not fair. I want to use the same kind of calculator that the Wright Brothers (Orville and Wilbur, IIRC) used.

[+flattie]

I have a 400T, can someone tell me the different between plot barometric pressure or ambiant pressure. I use this function just to track differential of the current conditions, vs an hour ago. IE, i want to know if the barometer is rising or falling, to track the weather. This has confused me since the beginning and it doesn't tell you anything in the manual. Thanks

 

From Garmin's FAQ, I'm assuming this applies to the 400t as well.

 

GO$Rs

 

Thanks GO$Rs, it also states in another section of the FAQ, that barometric pressure is better to use to track weather than ambiant pressure.

http://www8.garmin.com/support/faqs/faq.jsp?faq=138

Thanks for pointing me to this, I tried their site to no avail

[+julianh]

I have a 400T, can someone tell me the different between plot barometric pressure or ambient pressure. I use this function just to track differential of the current conditions, vs an hour ago. IE, i want to know if the barometer is rising or falling, to track the weather. This has confused me since the beginning and it doesn't tell you anything in the manual. Thanks

 

From Garmin's FAQ, I'm assuming this applies to the 400t as well.

 

GO$Rs

 

Thanks GO$Rs, it also states in another section of the FAQ, that barometric pressure is better to use to track weather than ambient pressure.

http://www8.garmin.com/support/faqs/faq.jsp?faq=138

Thanks for pointing me to this, I tried their site to no avail

Ambient Pressure is the absolute pressure at your current location and elevation, and is what the sensor in the unit measures directly. It is affected by both weather changes and elevation changes. It is really of academic interest only, because it is NOT used by the weather bureaus in any of their public reporting. Weather bureaus measure the ambient pressure at their sites, but convert to sea level (barometer) pressure in all their reports and charts.

 

The reason is because sea level pressure changes over a relatively small range - say 1,010 to 1,025 hPa most of the time, although it will drop under 1,000 hPa in a severe low (e.g. cyclone or hurricane), and can go up above 1,030 hPa under a very large high pressure system. Changes in elevation have a much bigger influence - every 9 metres of elevation rise is equivalent to approximately 1 hPa reduction in ambient pressure. If you plotted a map of ambient pressure instead of sea level pressure, it would end up being a topographical map rather than a weather map, because the pressure changes due to the weather would be totally swamped by the changes due to elevation.

 

What this means is that if you only want a rough indication of your elevation, you can get by with an uncalibrated barometric altimeter - typical changes in weather will give barometer pressure changes of the order of plus or minus 10 hPa say, and this will introduce errors of "only" about 100 metres. However, if you want an accurate estimate of your elevation, you need to know sea level (barometer) pressure, as well as ambient pressure, and use the difference between the two figures to get your current elevation.

 

The Garmin auto-calibration routine does this automatically, continually updating the current estimate of sea level (barometer) pressure, so that it can give a more accurate estimate of barometric elevation.

 

In general - make sure auto-calibration is turned on, and display "Barometer Pressure" rather than "Ambient Pressure". Watching the Barometer Pressure will indicate whether the weather is likely to be improving or worsening, and can be checked against weather reports.

 

"Ambient Pressure" is of no particular relevance to most casual users - although you can use it to predict the reduced boiling point of your kettle due to reduced air pressure at high altitude. This is VERY important to British mountaineers, who can't get a proper cup of tea when preparing for their final assault on Mt Everest, where the air pressure is so low that water boils at just 69 Celsius! http://en.wikipedia.org/wiki/Boiling_point

[+Michael]

It didnt give me that option

Inches was the only choice

that I saw

 

Setup->Units->Pressure->Millibars

 

GO$Rs

 

Thanks that will let me set it in millibars but my weather service gives me the pressure in inches. I don't have a source of millibar readings.

 

Interestingly enough the millibar setting does not allow me to enter more than the tenth. only one digit to the right or the decimal point.

 

So while its probably 1011.4 is more accurate than 29.8 its still not a enough for a proper calibration.

 

FYI To convert from Inches of mercury @32°F (inHg32) to millibars (mb) (inHg32) * 33.8639 = (mb). Now if the Colorado only had a calculator. (and a drink holder)

[+g-o-cashers]

Now if the Colorado only had a calculator. (and a drink holder)

 

Others->Calculator

 

GO$Rs

[+Michael]

Sorry it was a joke or at least an attempt at one. I knew it was there. It seemed funny at the time, really it did

[+julianh]

It didnt give me that option

Inches was the only choice

that I saw

 

Setup->Units->Pressure->Millibars

 

GO$Rs

 

Thanks that will let me set it in millibars but my weather service gives me the pressure in inches. I don't have a source of millibar readings.

 

Interestingly enough the millibar setting does not allow me to enter more than the tenth. only one digit to the right or the decimal point.

 

So while its probably 1011.4 is more accurate than 29.8 its still not a enough for a proper calibration.

 

FYI To convert from Inches of mercury @32°F (inHg32) to millibars (mb) (inHg32) * 33.8639 = (mb). Now if the Colorado only had a calculator. (and a drink holder)

Just out of interest - I assume the US weather bureau reports barometer pressure to 0.01 inches of mercury precision? If they are only reporting to 0.1 inch, you would get the pretty much same reading just about all the time!

 

Don't sweat the precision of the initial calibration TOO much - as long as you have auto-calibration turned on, the unit will start to self-correct itself straight away.

 

An error of 0.1 hPa / mbar is about 1 metre elevation error - basically, that is the limit of accuracy of the unit, so air pressure to a tenth of a hectopascal is plenty good enough to calibrate an altimeter.

 

An error of 0.1 inches of mercury is about 25 metres elevation error - more or less what you can expect from GPS elevation under typical conditions. In my experience, the unit should sort out that much error in the first half hour or so - just means you should do your initial calibration well before you actually need results, and leave the unit where it can maintain a good 3D fix to start the auto-calibration process.

 

(Colorado owners should lobby Garmin to allow barometer calibration to a reasonable precision, as can already be done on the eTrex range.)

Edited May 30, 2008 by julianh

[frozenflyboy]

 

Another good reason to switch to the metric system!

 

What was the other one?

OK - answer quickly, and no use of calculators:

 

How many inches in a mile?

 

How many ounces in a ton?

 

How many horsepower (or BTUs - you can select the unit of power of your choice!) does it take to lift a weight of one pound at a speed of 1 foot per second?

 

Equivalent questions in metric:

 

How many millimetres in a kilometre? A: 1,000,000

(Or if you prefer - How many centimetres in a kilometre? A: 100,000)

 

How many grams in a tonne? A: 1,000,000

 

How many watts to lift a weight of 1 newton at 1 metre per second? A: 1.000 W

 

And so on!

We changed to the metric system when I was in high school. I know the benefits of it and it is so clever but I and most people who were raised on the standard system still have a tough time with it. Subsequent generations will benefit from it but it will be a snowy day in "H E double hockey stick" when North America changes to Hpa in barometer readings. In Canada they give the metric readings out in the public weather because of the metric policy but I seriously doubt that anyone listens or knows what it means.

I remember when they changed the aircraft fuel system in Canada to Litres. I was flying couriers at the time and I knew that somebody somewhere would get in a big pickle over that one and sure enough an Air Canada jet landed about half way to their destination "dead-stick" when someone miscalculated. OooOOops. I used to calculate the fuel, then recalculate, then rerecalculate and then get the co-pilot to look over the numbers. I still convert everything back to standard. Once I rented an American car and drove into Canada. Of course everything was in standard on the dash but the roadsigns were in metric. I was driving a winding country road when I started to realize that I was way too fast. Then I noticed that I was traveling 90 MPH not 90 klicks (KM). True story.

 

You can show all the logic in the world about the metric system But it is tough to convert to it. The US has not had the courage to do it much to it's own disservice. It will regret that in the long run. Short term pain for long term gain. OK my speech is finished...

[+julianh]

I remember when they changed the aircraft fuel system in Canada to Litres. I was flying couriers at the time and I knew that somebody somewhere would get in a big pickle over that one and sure enough an Air Canada jet landed about half way to their destination "dead-stick" when someone miscalculated. OooOOops.

It's known as the "Gimli Glider":

http://en.wikipedia.org/wiki/Gimli_Glider

 

It's a famous incident, and was recognised to be one of the of the biggest metric conversion mistakes of all time - until the Mars Climate Orbiter ploughed into Mars because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA.

http://en.wikipedia.org/wiki/Mars_Climate_Orbiter

[frozenflyboy]

Wow what a great link. I remember it well. Used to be a joke about a controller in Ottawa telling a Canadian Airlines Intl. aircraft to follow (meaning taxi behind ) the Air Canada 767 ahead of him. He replied no we are continuing on non-stop to Edmonton...

Thanks Julianh

[+Team CowboyPapa]

We changed to the metric system when I was in high school. I know the benefits of it ...

Must be my oversight, I haven't located those benefits yet.

 

As noted above in post #12, the Wright brothers seemed to do quite well with other means.

 

By that I do not mean to imply that the metric is inferior; one can be successful in either, regardless. Or, neither guarantees sucess nor failure.

[+Team CowboyPapa]

 

It's a famous incident, and was recognised to be one of the of the biggest metric conversion mistakes of all time - until the Mars Climate Orbiter ploughed into Mars because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA.

Roger that. Which specification was as stupid as possible. Take one out of one's natural operational enviroment to give them every opportunity for a mistake.

 

Or, is to be inferred that the mission could not have been accomplished through sole use on the pounds-seconds-inch-foot system.

[+julianh]

 

It's a famous incident, and was recognised to be one of the of the biggest metric conversion mistakes of all time - until the Mars Climate Orbiter ploughed into Mars because a NASA subcontractor (Lockheed Martin) used Imperial units (pound-seconds) instead of the metric units (newton-seconds) as specified by NASA.

Roger that. Which specification was as stupid as possible. Take one out of one's natural operational enviroment to give them every opportunity for a mistake.

 

Or, is to be inferred that the mission could not have been accomplished through sole use on the pounds-seconds-inch-foot system.

WARNING: The following post is WAAAY off topic!

 

TCP,

 

No you can use ANY unit system you like, although in engineering applications, you MUST use a consistent units system, or else carry arbitrary "fudge factors" through all of your calculations.

 

For example - the fundamental equation for power:

 

P = F * V

 

In metric, you calculate all your forces in newtons, and your velocity in metres per second, and then multiply the two together to get power in watts. In imperial / US customary units:

 

P (hp) = 550 * F (lbf) * V (ft/s)

 

(I had to look this up on the net!)

 

For general members of the public, unit conversion issues are really not much more than a nuisance. For engineering applications, they can be catastrophic. For example, it is critical for engineers dealing in dynamics to understand that a pound mass and a pound force are NOT same thing. (Although I have met many US-trained engineers who don't understand this critical difference, and have constant battles with their dynamic calculations as a result. No such problem in SI metric, because we have quite different units for mass - the kilogram - and force - the newton.)

 

Personally, I am a big fan of the FFF System - length in furlongs, time in fortnights, mass in firkins, and then you can derive all other units (force, power, etc) from there.

http://en.wikipedia.org/wiki/FFF_System

 

Seriously, though - anyone who has truly made the shift from imperial / US customary to metric units will confirm - life is actually much easier when dealing with metric units. Sure, there is period of "pain" and confusion in the transition phase, and some people are never comfortable with the new units, but the change is truly beneficial once accomplished. (No arbitrary "fudge factors" in physical equations, fewer arithmetic errors, international standardisation, rational modular dimensions, etc.)

 

The biggest mistake many governments have made is in allowing long transition periods, and no enforcement of the change and deadlines. Britain and America in particular have been "going metric" for decades. Australia accomplished the complete change in less than one decade, and there are not too many people over here bemoaning the shift, I can assure you! (I was a schoolchild in the 70s, when the changeover was happening, and work for a global engineering company, so I have experience on "both sides of the fence".)

[frozenflyboy]

Ya gotta admit that a system where one of the main measurements (the foot) is supposedly based on Hercules foot size and is indeed much larger than a regular humans foot makes the system look a wee bit silly.

However the metric system is based on verifiable and reproduceable things;

one litre of water weighs 1 kilo and is a cubic decimetre.

 

(Taken from Wikipedia)

 

"In 1901, at the 3rd CGPM conference, the litre was redefined as the space occupied by 1 kg of pure water at the temperature of its maximum density (3.98 °C) under a pressure of 1 atm. This made the litre equal to about 1.000 028 dm3 (earlier reference works usually put it at 1.000 027 dm3).

 

In 1964, at the 12th CGPM conference, the original definition was reverted to, and thus the litre was once again defined in exact relation to the metre, as another name for the cubic decimetre, that is, exactly 1 dm3"

 

The definition of a yard is even more ridiculous.

 

(again from Wikipedia)

 

"The yard derives its name from the word for a straight branch or rod, although the precise origin of the measure is not definitely known. Some believe it derived from the double cubit, or that it originated from cubic measure, others from its near equivalents, like the length of a stride or pace. One postulate was that the yard was derived from the girth of a person's waist, while another claim held that the measure was invented by Henry I of England as being the distance between the tip of his nose and the end of his thumb. These are believed to be more likely standardising events than a random invention of the measure.[citation needed]"

 

Take the word gallon. There is imperial gallons and US Liquid and US dry. Almost seems like the difference was invented by some shyster.

 

Again from Wikipedia)

 

"U.S. liquid gallon is legally defined as 231 cubic inches, and is equal to 3.785411784 litres (exactly) or about 0.13368 cubic feet. This is the most common definition of a gallon in the United States. The U.S. fluid ounce is defined as 1/128 of a U.S. gallon.

U.S. dry gallon is one-eighth of a U.S. Winchester bushel of 2150.42 cubic inches, thus 268.8025 cubic inches (exactly) or 4.40488377086 litres (exactly). The U.S. dry gallon is less commonly used.

Imperial (UK) gallon is legally defined as 4.54609 litres (≈ 277.42 cu in), which is about 1.2 U.S. liquid gallons. This definition is used in Commonwealth countries and Ireland, and is based on the volume of 10 pounds of water at 62 °F. (A U.S. liquid gallon of water weighs about 8.33 pounds at the same temperature.) The Imperial gallon is no longer legal, in the United Kingdom, for trade or public administration purposes, but it is used colloquially (and in advertising) for fuel consumption figures in miles per gallon.

The Imperial gallon continues to be used as a unit of measure for fuel in Antigua and Barbuda, Belize, Burma, Grenada, Guyana, Sierra Leone and the United Arab Emirates."

 

Now all of this definition stuff makes the head spin which is why metric makes sense. The French came up with something right...... (I'm resisting my lower self... )

 

Think about it, the US sends aircraft all the world. In one country the pilot buys US gallons, in the next Imperial gallons, in the next litres. Nobody else uses US gallons. The world is a global economy. One day you're in the US and the next day China.

And after all that the only thing I understand is "how many miles per gallon does that thing get." Litres per 100 km means nothing to me.

OK my rant is over... I'm calmed down

[+Team CowboyPapa]

 

TCP,

 

No you can use ANY unit system you like, although in engineering applications, you MUST use a consistent units system, or else carry arbitrary "fudge factors" through all of your calculations.

 

For general members of the public, unit conversion issues are really not much more than a nuisance. For engineering applications, they can be catastrophic. For example, it is critical for engineers dealing in dynamics to understand that a pound mass and a pound force are NOT same thing. (Although I have met many US-trained engineers who don't understand this critical difference, and have constant battles with their dynamic calculations as a result. No such problem in SI metric,...........

Not a problem for me, either. I'm quite comfortable in pounds force and pounds mass.

 

But is like walking out the door and bring your credit card along and don't forget your 32.2 pounds mass per pound force per ft per second squared.

Edited June 3, 2008 by Team CowboyPapa

[+Team CowboyPapa]

 

"U.S. liquid gallon is legally defined as 231 cubic inches, and is equal to 3.785411784 litres (exactly) or about 0.13368 cubic feet. This is the most common definition of a gallon in the United States. The U.S. fluid ounce is defined as 1/128 of a U.S. gallon.

FFB,

 

Would it surprise you to know that the engineering for launch vehicles which place the GPS satellites into their orbits is entirely the US non-metric system? And now that you mention gallons, it is that unit of volumetric measurement which is used for the fuel loading of the first stage booster? Would it amaze you that the fuel loaded onto the first stage is measured with a gauge much like the water meter outside your residence. However, this gauge, like the one outside my house is calibrated in gallons. Amazing how it all still works, huh?

[+julianh]

FFB,

 

Would it surprise you to know that the engineering for launch vehicles which place the GPS satellites into their orbits is entirely the US non-metric system? And now that you mention gallons, it is that unit of volumetric measurement which is used for the fuel loading of the first stage booster? Would it amaze you that the fuel loaded onto the first stage is measured with a gauge much like the water meter outside your residence. However, this gauge, like the one outside my house is calibrated in gallons. Amazing how it all still works, huh?

Yes, it would - very much!

 

NASA has been fully metric for some time (apart from some of their suppliers, of course!)

 

NASA Policy Directive NPD 8010.2E states in part:

 

a. The International System of Units (commonly known as the SI - Systeme Internationale - or metric system of measurement) is the preferred system of weights and measurement for NASA programs and projects.

 

Compliance with this policy directive is mandatory.

http://nodis3.gsfc.nasa.gov/npg_img/N_PD_8..._002E__main.pdf

 

I realise that the GPS satellites come under the auspices of the defence forces, rather than NASA, but even the US military is substantially metric:

 

The U.S. military uses metric measurements extensively to ensure interoperability with allied forces, particularly NATO STANAGs, "standardization agreements".

http://en.wikipedia.org/wiki/Metrication_i...e_United_States

 

The Delta II launch vehicles are manufactured by Boeing - and Boeing has also gone metric. In the following links, the primary units are always given in metric, with US customary units as bracketed equivalents:

http://www.boeing.com/defense-space/space/...lta2/delta2.htm

http://www.ulalaunch.com/docs/product_shee...rsGuide2007.pdf

 

And I sincerely doubt that the fuel is actually loaded up in gallons - far more likely that the fuel would be loaded by mass rather than by volume, because mass is critical for space launches, and the density of liquid fuels will vary significantly as their temperature changes, and therefore so would the actual quantity that you can fit into each litre or gallon (which are volumetric measurements). If you have seen references to fuel capacity in gallons, it is more likely this is a derived measurement, because people generally have a better understanding of a litre (or gallon) of fuel than a kilogram (or pound) of fuel - but in critical applications, it is the mass of fuel which matters more than the volume. Note that in aviation, fuel is loaded either in pounds (in the US) or kilograms (pretty much the rest of the world), not gallons or litres, because of the variable density.

 

While the rockets may well have once been designed in the USA using US customary units, the space program now runs primarily under metric units, with US customary units being secondary.

 

OK, TCP - now it's MY turn to challenge YOU - show us the documentary evidence that the GPS launches are conducted using US customary units, not metric; and that fuel is loaded by gallons (volume) rather than by mass. (And news/media sources or magazine clippings won't cut it, because in the US they will generally convert to US customary units - often erroneously - because that is what the US public knows and expects.)

Edited June 3, 2008 by julianh

[+Team CowboyPapa]

 

OK, TCP - now it's MY turn to challenge YOU - show us the documentary evidence that the GPS launches are conducted using US customary units, not metric; and that fuel is loaded by gallons (volume) rather than by mass. (And news/media sources or magazine clippings won't cut it, because in the US they will generally convert to US customary units - often erroneously - because that is what the US public knows and expects.)

Well, with that level of evidence being required, I just can't cut it. It was not my practice to remove those documents from company property. And they may have changed since I left the launch vehicle program 8 years ago. However, at that time everything we did was in English units, including the first stage fuel load in gallons. Hey, I'm meeting a guy who still works Delta II (most have gone on to ULA in Denver) for lunch tomorrow, so check back. In any event, you have two choices: I'm a complete liar who sucked you into an argument and will say anything, or it's real. Whaddya' think?

[+julianh]

But is like walking out the door and bring your credit card along and don't forget your 32.2 pounds mass per pound force per ft per second squared.

I'm sorry, but you have lost me here:

 

Did you mean:

 

32.2 lbm / lbf / (ft / s^2) = 1.00 s^4 / ft^2 = 1,036 / g^2 = 1,036 per g squared

(No, I guess not - that doesn't make any sense at all!)

 

Or:

 

32.2 lbm / lbf / ft / s^2 = 1.00 / ft^2

(i.e. "Don't forget your one per square foot", whatever that means!?)

 

Or possibly you meant to say:

 

32.2 pounds mass per pound force times (ft per second squared)

32.2 lbm / lbf * ft / s^2 = 1.00 (unitless)

(i.e. "Don't forget your one" - again, I don't get it.)

 

Either way - I haven't got the foggiest what you are trying to say!? Would you care to convert to metric units, so we can all share the joke?

[+julianh]

 

OK, TCP - now it's MY turn to challenge YOU - show us the documentary evidence that the GPS launches are conducted using US customary units, not metric; and that fuel is loaded by gallons (volume) rather than by mass. (And news/media sources or magazine clippings won't cut it, because in the US they will generally convert to US customary units - often erroneously - because that is what the US public knows and expects.)

Well, with that level of evidence being required, I just can't cut it. It was not my practice to remove those documents from company property. And they may have changed since I left the launch vehicle program 8 years ago. However, at that time everything we did was in English units, including the first stage fuel load in gallons. Hey, I'm meeting a guy who still works Delta II (most have gone on to ULA in Denver) for lunch tomorrow, so check back. In any event, you have two choices: I'm a complete liar who sucked you into an argument and will say anything, or it's real. Whaddya' think?

TCP,

 

It was not my intention to insult anyone or in any way malign their honesty or reputation. If I have offended, I apologise whole-heartedly and unreservedly.

 

(However, please don't expect me to apologise for supporting the rational metric system over the archaic US customary system, or for pointing out the facts of the extent of adoption of the metric system within the US! )

[+Team CowboyPapa]

 

It was not my intention to insult anyone or in any way malign their honesty or reputation. If I have offended, I apologise whole-heartedly and unreservedly.

 

Hey, no offense taken by me and I know that none was intended toward me as it was not my intention to offend with my questions and responses. If I were one to be afraid of being offended from time time, I wouldn't be here. I'd be somewhere else like............... I dunno'.

 

Apologies for the above, I think that I stuck an extra "per" in there. From Wikipeida:

In the "engineering" fps system, the weight of the mass unit (pound-mass) on Earth's surface is approximately equal to the force unit (pound-force). The price for this convenience is that the force unit is not equal to the mass unit multiplied by the acceleration unit[6]—the use of Newton's Second Law, F = ma, requires another factor, gc, usually taken to be 32.17405 lb·ft/(lbf·s²).

Where the indicate pound-force with lbf and pound-mass with just lb (I always use lbm for that).

[+CacheARRRS]

What makes me laugh, is that all this talk about metric, NASA, Boeing, gallons, newtons, goes to such lengths... but you all use Wikipedia as a source?!?!?!?!?!?!

 

I made a giant poster for my teacher friends for just such an occasion. It reads;

 

"Wikipedia is no more credible than the scribbles on a bathroom wall. No matter how accurate it seems, the author may still be full of $#!%"

[+Michael]

for what its worth

 

GENERAL RULES FOR USING THE BAROMETER

TO FORECAST LOCAL WEATHER

Barometric pressure decrease indicates coming stormy weather, rain, wind, , heat.

 

Barometric pressure rise indicates fair, dry, colder weather.

 

Slow, regular and moderate fall in pressure indicates low pressure area is passing at a distance. Any marked change in weather unlikely.

 

Sudden decrease, even if small, indicates a nearby disturbance; normally bringing wind, and short showers.

 

Large pressure drop signals a coming storm in 5 to 6 hours.

 

Large, slow and sustained decrease indicates a long period of poor weather. Coming weather will be more

pronounced if pressure started rising before dropping.

 

Sudden rise of pressure,when the pressure is about average or above average and the weather is fair, indicates approach of a low pressure cell, and the barometer will soon start to come down.

 

Rapid rise when the pressure is low, announces a short period of fair weather.

 

If pressure rise is large and prolonged, count on a many days of good weather ahead.

 

Definition of Pressure Tendency Terms

Term________________________Pressure Tendency Over 3 Hours

Steady ______________________Less than 0.1 mb

Rising or falling slowly __________0.1 to 1.5 mb

Rising or falling _______________1.6 to 3.5 mb

Rising or falling quickly _________3.6 to 6.0 mb

Rising or falling very rapidly _____More than 6.0 mb

 

Sloppy rule of thumb. 3mb = 0.1" (no one argue with me I said it was sloppy. )

 

Edited June 6, 2008 by Michael