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View Poll Results: Do you use Knots , MPH, or Kilometers To Describe Your Speed?
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I use Knots.
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279 |
74.20% |
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I use MPH
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93 |
24.73% |
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I use kilometers per hour.
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4 |
1.06% |

01-30-2012, 09:01 AM
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Join Date: Mar 2007
Location: 45G, Brighton, MI
Posts: 1,867
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Quote:
Originally Posted by Jamie
Virtually every single reference to speed and distance in every aeronautical document, chart, sectional, AIM, FAR, not to mention every controller uses nautical miles.
It's the unit for the system. Anything else is just for bragging rights.
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THE system for bragging rights is furlongs per fortnight, eighths of a mile (statute  ) per two weeks.
Flying at 7500ft is fairly handy in my 170 as the indicated mph is pretty close to true knots.
__________________
Miles (VAF# 1238, Paid up as of 2018)
RV-7 TU 904KM (reserved)
Wings Fitted and Finish Kit on site
Construction Log
Picasa: Empennage Album, Wings Album, Fuselage Album
1955 Cessna 170B flying since 1982
'To get something you never had, you have to do something you never did.' -Unk.
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01-30-2012, 09:33 AM
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Join Date: Sep 2011
Location: Edgewater, FL. KSFB
Posts: 1,118
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Knots
Learned to fly in an old 172 with MPH. My instructor told me to use the inner numbers (knots) not the outer ring with the wrong numbers. Since then I have been flying newer 172's with knots. Learned to fly IFR using knots. Started visiting this site and many RV'ers were using the MPH and I am thinking "What the heck".
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01-30-2012, 11:55 AM
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Join Date: May 2005
Location: Santa Barbara, CA
Posts: 1,324
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"Back in the day" when I bought my used B-55 Baron, it was equipped with a dual scale A/S with knots on the inside ring. I sent the gauge off to the instrument shop where they rescreened the face to show only knots. Come to think of it, the last airplane I had with an MPH A/S was my J3 Cub, which I sold in 1970
John Clark ATP, CFI
FAAST Team Representative
EAA Flight Advisor
RV8 N18U "Sunshine"
KSBA
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01-30-2012, 11:30 PM
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Join Date: Jun 2010
Location: Sydney, Australia
Posts: 123
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Quote:
Originally Posted by longranger
THE system for bragging rights is furlongs per fortnight, eighths of a mile (statute  ) per two weeks.
Flying at 7500ft is fairly handy in my 170 as the indicated mph is pretty close to true knots.
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I was wondering how long it would take for "furlongs" to be mentioned! 
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01-31-2012, 12:14 AM
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Join Date: Nov 2005
Posts: 1,256
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Quote:
Originally Posted by dutchroll
I was wondering how long it would take for "furlongs" to be mentioned! 
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I like slugs as the unit of mass, too. 
__________________
Steve "Flying Scotsman"
Santa Clarita, CA
PP-ASEL, ASES, Instrument Airplane
RV-7A N660WS flying!
#8,000
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01-31-2012, 12:34 AM
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Join Date: Jan 2008
Location: KTCY
Posts: 643
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Quote:
Originally Posted by MarkW
Learned to fly in an old 172 with MPH. My instructor told me to use the inner numbers (knots) not the outer ring with the wrong numbers. Since then I have been flying newer 172's with knots. Learned to fly IFR using knots. Started visiting this site and many RV'ers were using the MPH and I am thinking "What the heck".
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The numbers are bigger 
__________________
Dave & Trina
RV-9A Flying  - 330 Hrs. Painted  Finishing the interior.
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01-31-2012, 12:45 AM
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Join Date: Jun 2010
Location: Sydney, Australia
Posts: 123
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Heh, I vaguely remember "slugs" from my aerodynamic days at uni. But I don't think I ever did understand why someone came up with such a unit!
Hey Vlad, if it's any consolation, I like the metric system and think it makes emminent sense (we converted down under several decades ago, and I speak "both" languages despite my public disdain for mph). But I think the hotchpotch of "standard" aeronautical units is here to stay for a while! 
__________________
Mike
Down Under
Last edited by dutchroll : 01-31-2012 at 12:49 AM.
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01-31-2012, 01:21 AM
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Join Date: Nov 2005
Posts: 1,256
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I've actually never understood why certain manufacturers (certificated or experimental) would mark their systems in mph. The *system*, at least in the U.S., uses knots and nautical miles. I've never heard an ATC specialist ask for or assign any speed in miles per hour.
As some of us know all too well, mixing measurement systems can be a recipe for disaster...
At least nautical miles and meters are related to measurements of the earth...1 nm = 1 minute of arc, 1 meter = 1/10,000,000th of the distance from the equator to the pole). Statue miles are essentially arbitrary.
(BTW, a Roman pace was *two* steps, not one...)
(I don't know if it's actually true or not, but my physics prof asserted that if you use the furlongs/fortnight/slug system, virtually all physical constants end up being approximately 1 x 10^some power  I suspect he just made that up to see if we were listening!)
Can you tell I'm up late and bored tonight? LOL!
__________________
Steve "Flying Scotsman"
Santa Clarita, CA
PP-ASEL, ASES, Instrument Airplane
RV-7A N660WS flying!
#8,000
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01-31-2012, 04:29 AM
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Join Date: Dec 2008
Location: na
Posts: 1,457
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The ATC already mixes systems...
Wx is reported in statute miles and therefore the visibility portion of approach minima are published in statute miles...
why do we use Feet instead of meters?
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01-31-2012, 06:51 AM
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Join Date: Sep 2010
Location: Charlotte NC
Posts: 1,167
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Quote:
Originally Posted by RV8R999
The ATC already mixes systems...
Wx is reported in statute miles and therefore the visibility portion of approach minima are published in statute miles...
why do we use Feet instead of meters?
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I think the feet verses meters issues was decided by Pan Am. Much of the worlds conventions on how we fly date back to their early days where there were no standards. Not all nations however use the ICAO standard of feet. Its a pain in the ____ flying in countries that do not with a aircraft set up for feet. Leveling at 11100 meters is one thing but when they ask you your altitude passing and its 26,700 feet by the time my slow brain has done the conversion to meters the number is history not where we are at the moment. Approaches get especially tricky because they often convert from meters standard to local altimeters at very low altitudes like 1200 meters. Add in another conversion since the same countries often use QFE instead of QNH for altimeter settings and things get interesting for the math inept among us.
George
Last edited by sailvi767 : 01-31-2012 at 06:55 AM.
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