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01-08-2017, 06:54 AM
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Join Date: Mar 2008
Location: houston, texas
Posts: 900
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Your call
Me too for all the above reasons. Kts. Only one little addition.
The more you fly the more math you will be doing in your head as you go.
It may help you to make a cheat sheet and start getting used to a few conversions. This is one you will know by hart after a while " 1.151" Sm. to Kts.
I find myself even doing it on a road map some times. Hope this helps. Yours as always, R.E.A. III #80888
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01-08-2017, 07:17 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 dutchroll
Suffice to say it's a hangover from days long gone by. I did read a great story about the Mooney 201 which apparently was named because it could reach 201 mph in level flight, and "Mooney 175" (in knots) just didn't have the same marketing "zing"! Maybe they should've gone full metric and named it the "Mooney 323"?
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The "days long gone by" date back about four decades...
In the mid 1970's GAMA (General Aviation Manufacturing Association) recommended all manufacturers standardize on knots and so most but not all switched (Maule for example still to this day uses MPH calibrated airspeeed indicators).
My 1977 Tiger was made in the first year the factory switched from mph to knots on the ASI and placards.
__________________
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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01-08-2017, 07:18 AM
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Join Date: Mar 2010
Location: KSGJ / TJBQ
Posts: 2,039
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Quote:
Originally Posted by Robert Anglin
It may help you to make a cheat sheet and start getting used to a few conversions. This is one you will know by hart after a while " 1.151" Sm. to Kts.
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Another handy quick conversion. For centigrade to fahrenheit, double the degrees centigrade then add 30.
Example: How many degrees fahrenheit is 15 degrees centigrade? Answer; 15*2 = 30, then add 30 which gives you 60 degrees F. While not exact (in this case it is actually 59F) it will be close enough for most of our applications and especially for getting an idea of what the temperature is.

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Galin
CP-ASEL-AMEL-IR
FCC Radiotelephone (PG) with Radar Endorsement
2020 Donation made
www.PuertoRicoFlyer.com
Last edited by GalinHdz : 01-08-2017 at 07:22 AM.
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01-08-2017, 07:26 AM
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Join Date: Nov 2005
Location: Asheville, NC
Posts: 2,692
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Quote:
Originally Posted by RV7A Flyer
so it's cooler than the arbitrary distance of a statute mile  .
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So whats arbitrary about 1000 paces of an ancient Italian dude in fighting gear??  
Seriously though, I agree with the crowd. Knots.
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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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01-08-2017, 07:43 AM
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Join Date: Oct 2006
Location: TX
Posts: 53
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Knots vs mph
I'm not throwing any sand in the gears here as I use both knots and mph depending on the airplane I'm flying, however if you look at the performance specification of every RV model, Vans aircraft (ya the mothership) uses MPH. Go figure
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01-08-2017, 08:00 AM
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Join Date: Jan 2017
Location: Ozark, AL
Posts: 62
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Quote:
Originally Posted by vetterman
I'm not throwing any sand in the gears here as I use both knots and mph depending on the airplane I'm flying, however if you look at the performance specification of every RV model, Vans aircraft (ya the mothership) uses MPH. Go figure
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Of course. MPH "briefs" better to buyers 
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Adam Wright
RV-8 Builder 83611
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01-08-2017, 08:32 AM
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Join Date: Jul 2006
Location: Longmont, CO
Posts: 215
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1:60 rule works with knots
1 NM = 6000' is the basis of the 1:60 rule. You're 3 degrees off the localizer at 10 NM from the field. How far off are you (so you can plan your lead point turn)? 3/6 or 1/2 mile, or 3000'. The math also works well for desecent planning. Most of this is unnecessary if we rely on the electronics, but Inkeep the mental math sharp for when the electronics fail.
David
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David Dalton
Longmont, CO
RV-7 Complete,
Flies like a dream!
Lifetime VAF Member
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01-08-2017, 08:33 AM
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Join Date: Apr 2010
Location: Covid Country-SoCal
Posts: 1,081
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Quote:
Originally Posted by GalinHdz
What does visibility have to do with speed?
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I was referring to the statement that if its aviation, use knots. The FARs make reference to the VFR cloud clearance and visibility requirements for different airspace in statute miles.
-Marc
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RV-10
N814RV
2020 Donation Made
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01-08-2017, 08:38 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 rzbill
So whats arbitrary about 1000 paces of an ancient Italian dude in fighting gear??  
Seriously though, I agree with the crowd. Knots.
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The knot (actually nautical mile) was only a good guess when it was invented...
1852*m is the length of the internationally agreed nautical mile. The US adopted the international definition in 1954, having previously used the US nautical mile (1853.248*m).[4] The UK adopted the international nautical mile definition in 1970, having previously used the UK Admiralty nautical mile (6080*ft [1853.184*m]).
How the mile changed over time and by country away from the Roman soldier definition is also interesting -
https://en.wikipedia.org/wiki/Mile
__________________
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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01-08-2017, 08:44 AM
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Join Date: Jan 2007
Location: Stuart, FL /Hartford, CT/Virgin Gorda,BVI
Posts: 3,122
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i use both from my complicated past. in the plane i use both also. it is easy to go back and forth. 7 mph = 8 knots.
how did they come up with knots? well before we were in the air. the sailors of long ago had a rope with knots in it it. throw it out in the water and count the knots that go out in a specified time. 
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Ed D'Arcy
RV6-A 5,200+ hrs, R-44 1,600 hrs, Helicycle 320 hrs, gyro sold,35,000 miles flown in 2015 
Stuart, Fl / S WINDSOR,Ct / Virgin Gorda, BVI - under major repair from hurricane damage
VAF #840 EAA AOPA FAC FABA QB SPA
addicted pickle ball player
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