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01-10-2017, 07:19 AM
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Join Date: Mar 2008
Location: houston, texas
Posts: 900
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Metric
Quote:
Originally Posted by RV7A Flyer
I hope they're faster than that
Quickie on-line conversion tool says 170 kts = 525859 furlongs/fortnight! Impress your friends: "This plane goes over half a million furlongs per fortnight! And it only weighs about 35 slugs!"
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You know we are supposed to use metric if we can according to Jimmy Carter.
mm. per second would be about as good as you could want to state.
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01-10-2017, 09:52 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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884,800,000,000,000,000,000 Angstroms per Aeon????
__________________
Bill Pendergrass
ME/AE '82
RV-7A: Flying since April 15, 2012. 850 hrs
YIO-360-M1B, mags, CS, GRT EX and WS H1s & A/P, Navworx
Unpainted, polished....kinda'... Eyeballin' vinyl really hard.
Yeah. The boss got a Silhouette Cameo 4 Xmas 2019.
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01-10-2017, 10:07 AM
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Join Date: Oct 2009
Location: Edson, Alberta, Canada
Posts: 483
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MPH or Knots
Here in Canada where I trained in 1981 it was done in MPH for me and I have always had an ASI that indicated MPH and knots were in small letters.
I have noticed the switch in the newer model planes I rent especially the ASI and struggle sometime with the :"conversion". Similar to our late PM sending us into "metric" chaos this does make for some trouble sometimes in the pattern; "have i trimmed for 70 MPH or have i trimmed for 70 knots?"
That is where the fun of this issue ENDS! I hate that momentary confusion on final and twinge of non confidence. So I fly er by the feel and use the ASI as a guide the way we were meant to.
I always just add 10 to the new plane ASI(knots) and hope it is "close enough".
Great thread here! Us old guys always need training eh?
__________________
Dave Cobb
[color="Red"]=VAF=2019 Donation - and a bit extra for great work![/COLOR="blue"]
Empennage RV 7 - Tipper
Wings complete
Dynon installed and running
Fuse closer to completion, Canopy complete
AME reviewed and repaired O-320-Lyc installed
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01-10-2017, 11:10 AM
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Join Date: Dec 2009
Location: Montreal
Posts: 1,456
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At my Engineering school the problems on assignments and exams mixed up the units. The questions defined the desired units for the answer and you had to convert. Distance could be feet, meters, inches etc. Temps could be C or F, speeds in mph, kph or knots, and the worst, mass, could be kg or slugs. Slugs were my arch nemesis. Try to explain to a layperson why you buy hamburger at the grocery store in units of force (lbs) in America and units of mass (kg) in Canada. Try to explain that a model airplane servo torque rating in g/cm (not even g-cm) is wrong.
Interestingly, after that space probe slammed into Mars a bunch of years back, NASA has gone all metric to avoid a similar screw up. But at the aircraft company where I work, which is in Canada, which is officially metric, we work in imperial units. We will kick out the afm in metric for European customers if they ask for it.
The problem with establishing standards is that it requires humans to agree on something. Humans don't like agreeing on stuff in my experience and I think this thread illustrates that very well
Now about that primer....
__________________
Scott Black
Old school simple VFR RV 4, O-320, wood prop, MGL iEfis Lite
VAF dues 2020
Instagram @sblack2154
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01-10-2017, 11:16 AM
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Join Date: Jan 2005
Location: 57AZ - NW Tucson area
Posts: 10,011
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Quote:
Originally Posted by sblack
At my Engineering school the problems on assignments and exams mixed up the units. The questions defined the desired units for the answer and you had to convert. Distance could be feet, meters, inches etc. Temps could be C or F, speeds in mph, kph or knots, and the worst, mass, could be kg or slugs. Slugs were my arch nemesis. Try to explain to a layperson why you buy hamburger at the grocery store in units of force (lbs) in America and units of mass (kg) in Canada. Try to explain that a model airplane servo torque rating in g/cm (not even g-cm) is wrong.
Interestingly, after that space probe slammed into Mars a bunch of years back, NASA has gone all metric to avoid a similar screw up. But at the aircraft company where I work, which is in Canada, which is officially metric, we work in imperial units. We will kick out the afm in metric for European customers if they ask for it.
The problem with establishing standards is that it requires humans to agree on something. Humans don't like agreeing on stuff in my experience and I think this thread illustrates that very well
Now about that primer....
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The colonies may have trouble, but I'm always amused at the UK's conversions.
All there are now used (EU based) to buying stuff in kilos and feeling C temperatures, but they still drive in miles and mph, buy petrol in litres but still use MPG for fuel economy... 
__________________
Gil Alexander
EAA Technical Counselor, Airframe Mechanic
Half completed RV-10 QB purchased
RV-6A N61GX - finally flying
Grumman Tiger N12GA - flying
La Cholla Airpark (57AZ) Tucson AZ
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01-10-2017, 01:09 PM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by sblack
Interestingly, after that space probe slammed into Mars a bunch of years back, NASA has gone all metric to avoid a similar screw up.
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I think you mean the one that *missed* Mars, Mars Climate Orbiter.
NASA had been specifying SI units for many years prior to that, but the lower-level software was incorrectly coded (did not adhere to interface spec for SI units, and not caught during V&V).
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01-10-2017, 03:32 PM
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VAF Moderator / Line Boy
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Join Date: Jan 2005
Location: Dayton, NV
Posts: 12,256
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Quote:
Originally Posted by RV7A Flyer
I think you mean the one that *missed* Mars, Mars Climate Orbiter.
NASA had been specifying SI units for many years prior to that, but the lower-level software was incorrectly coded (did not adhere to interface spec for SI units, and not caught during V&V).
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Which units you used at NASA depended on which program you were working. The ISS actually has used both. Shuttle was built all imperial, but we used a lot of metric once we started working with the Russians. The truth was - we had to be able to work in both, and regularly convert.
When doing maneuvers, I mostly wanted to make sure I wasn't off by a factor of three (meters per second versus feet per second). And we changed from fps on orbit to knots on the way downhill..... 
__________________
Paul F. Dye
Editor at Large - KITPLANES Magazine
RV-8 - N188PD - "Valkyrie"
RV-6 (By Marriage) - N164MS - "Mikey"
RV-3B - N13PL - "Tsamsiyu"
A&P, EAA Tech Counselor/Flight Advisor
Dayton Valley Airpark (A34)
http://Ironflight.com
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01-10-2017, 08:13 PM
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Join Date: Jul 2013
Location: US
Posts: 2,251
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Quote:
Originally Posted by Ironflight
Which units you used at NASA depended on which program you were working. The ISS actually has used both. Shuttle was built all imperial, but we used a lot of metric once we started working with the Russians. The truth was - we had to be able to work in both, and regularly convert.
When doing maneuvers, I mostly wanted to make sure I wasn't off by a factor of three (meters per second versus feet per second). And we changed from fps on orbit to knots on the way downhill..... 
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Yeah, Paul, in truth...even though the policy has been metric for a while, a lot of mechanical stuff on our flight vehicles has been and still is imperial. Old habits die hard. But for MCO, the specs on the s/w were clear...SI units. It just was coded wrong and never caught. 
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01-11-2017, 02:27 AM
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Join Date: Jun 2010
Location: Sydney, Australia
Posts: 123
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Quote:
Originally Posted by sblack
The problem with establishing standards is that it requires humans to agree on something. Humans don't like agreeing on stuff in my experience and I think this thread illustrates that very well 
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I think it's more that people don't like change. Especially major change. It's big and scary and too hard. Even if it makes more sense in the longer term.
I like knowing everything is a factor of 10 and that prefixing it with "milli_ centi_ kilo_ etc" all means something consistent. It's consistent with the entire decimal numbering system. Dividing something up into quarters, eighths, sixty-fourths to get smaller but multiplying by 12, then 3, then 1760 to get bigger.......who the heck thought that system up?
But, as I said earlier, ya gotta be at least bilingual to get by these days! 
__________________
Mike
Down Under
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01-11-2017, 09:41 PM
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Join Date: Sep 2013
Location: Olds, AB
Posts: 83
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Quote:
Originally Posted by N941WR
If you have an EFIS, it should be easy to swap between the two with a few button pushes.
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I flew off my test hours in MPH because I was comfortable with them after 20 years of renting and owning small Cessnas and Pipers, and because my transition trainer (Old Blue) used MPH. I switched the Dynon to KTS after I started flying around our countries and talking to ATC a lot. It took a few circuits to get used to the "new" approach speed, but I never considered changing back.
When I want to impress my non-pilot Canadian friends, I tell them cruise speed is 280 klicks, with top speed of 340 
Jay
__________________
RV7-A
C-FXPT
IO-375, Catto, Electroair, Skyview
400 hours
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