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Knots vs. MPH

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ronschreck

Joined: 04 Aug 2006
Posts: 192
Location: Gold Hill Airpark, NC (NC25)

Posted: Sat Jun 09, 2007 5:04 am Post subject: Knots vs. MPH

I'm donning my nomex in preparation for the flamers.  Here's my question... Why oh why do RVers continue to use statute miles and MPH?  I am currently on a tour with ten other RV's and we often exchange range and speed while inflight to keep the various flights in order.  I was brought up on knots and nautical miles and it throws me for a loop when we have a few who insist on calling out speeds and ranges in MPH and statute miles.  All military services use knots, commercial airlines use knots, aeronautical charts are scalled based on nautical miles and ATC uses knots.  As far as I can determine, the only reason GA has clung to MPH is because it sounds faster.  Maybe it started with the Mooney 201?  Sounds better to say your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other than the vanity factor, I see no real good reason to use MPH and I would hope that those of you currently building your RV's would consider this when you purchase your airspeed indicator o

 r calibrate your whiz bang EFIS.  



OK... end of rant.  Tell my why not use knots!



Ron Schreck

RV8, "Miss Izzy"

Gold Hill Airpark, NC



on the way to Cody, WY

n395v

Joined: 10 Jan 2006
Posts: 450

Posted: Sat Jun 09, 2007 5:20 am Post subject: Re: Knots vs. MPH

Can't speak for others but eons ago when I trained all the ASIs in the trainers (Cessnas and Pipers) where in MPH. Same when I was an active CFI.



I converted my brain to knots when I started flying a lot of ifr and like you I fly using knots/nautical.



If you go to the performance pages on Vans website the RV numbers are in MPH so I think it natural many builders would follow this convention.



With GPSs and EFISs today there is little benefit re charts to the VFR pilot converting his brain to think in knots.



Kinda like English vs metric.



I guess it boils down to personal preference.

_________________
Milt

bill(at)vondane.com
Guest

Posted: Sat Jun 09, 2007 5:45 am Post subject: Knots vs. MPH

If you use knots you will be charges higher user fees!!   



please do not archive... 



N395V wrote:

 	  Quote: 	
		   



 Can't speak for others but eons ago when I trained all the ASIs in the trainers (Cessnas and Pipers) where in MPH. Same when I was an active CFI.



 I converted my brain to knots when I started flying a lot of ifr and like you I fly using knots/nautical.



 If you go to the performance pages on Vans website the RV numbers are in MPH so I think it natural many builders would follow this convention.



 With GPSs and EFISs today there is little benefit re charts to the VFR pilot converting his brain to think in knots.



 Kinda like English vs metric.



 I guess it boils down to personal preference.



 --------

 Milt

 2003 F1 Rocket

 2006 Radial Rocket

 website http://www.excaliburaviation.com





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=117448#117448

Kellym

Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ

Posted: Sat Jun 09, 2007 5:55 am Post subject: Knots vs. MPH

Maybe because they only have mph on their airspeed indicator and aren't 

so good at conversions.

BTW, 201 mph =~ 175kts. ;-p



Ron Schreck wrote:

 	  Quote: 	
		   



 I'm donning my nomex in preparation for the flamers.  Here's my question... Why oh why do RVers continue to use statute miles and MPH?  I am currently on a tour with ten other RV's and we often exchange range and speed while inflight to keep the various flights in order.  I was brought up on knots and nautical miles and it throws me for a loop when we have a few who insist on calling out speeds and ranges in MPH and statute miles.  All military services use knots, commercial airlines use knots, aeronautical charts are scalled based on nautical miles and ATC uses knots.  As far as I can determine, the only reason GA has clung to MPH is because it sounds faster.  Maybe it started with the Mooney 201?  Sounds better to say your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other than the vanity factor, I see no real good reason to use MPH and I would hope that those of you currently building your RV's would consider this when you purchase your airspeed indicator o

  r calibrate your whiz bang EFIS.  



 OK... end of rant.  Tell my why not use knots!



 Ron Schreck

 RV8, "Miss Izzy"

 Gold Hill Airpark, NC



 on the way to Cody, WY

_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD

ceengland(at)bellsouth.ne
Guest

Posted: Sat Jun 09, 2007 5:59 am Post subject: Knots vs. MPH

Ron Schreck wrote:

 	  Quote: 	
		   

 

 I'm donning my nomex in preparation for the flamers.  Here's my question... Why oh why do RVers continue to use statute miles and MPH?  I am currently on a tour with ten other RV's and we often exchange range and speed while inflight to keep the various flights in order.  I was brought up on knots and nautical miles and it throws me for a loop when we have a few who insist on calling out speeds and ranges in MPH and statute miles.  All military services use knots, commercial airlines use knots, aeronautical charts are scalled based on nautical miles and ATC uses knots.  As far as I can determine, the only reason GA has clung to MPH is because it sounds faster.  Maybe it started with the Mooney 201?  Sounds better to say your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other than the vanity factor, I see no real good reason to use MPH and I would hope that those of you currently building your RV's would consider this when you purchase your airspeed indicato

r o
	


 	  Quote: 	
		    r calibrate your whiz bang EFIS.  

 

 OK... end of rant.  Tell my why not use knots!

 

 Ron Schreck

 RV8, "Miss Izzy"

 Gold Hill Airpark, NC

 

 on the way to Cody, WY

Let's settle this once & for all. Use kilometers. Universal (except in 
	


the US & England), bigger numbers for the speed freaks. Everybody Wins!

rv9jim(at)juno.com
Guest

Posted: Sat Jun 09, 2007 6:19 am Post subject: Knots vs. MPH

Hi Ron,

        Its is almost like the guys who put in the dual scale /tas air

speed indicator.  Man that is so full of stuff it is hard to read

anything accuratly.  I went the simple route and installed the single

scale  0-200 'Knot" airspeed indicator.  Added my colored bands and it is

so easy to use that way. Much easier to read for the poor old eyes and

brain to absorb.   Flame on---

Jim Nelson



do not archive

jsflyrv(at)verizon.net
Guest

Posted: Sat Jun 09, 2007 6:32 am Post subject: Knots vs. MPH

Because knots are for boats.  it would be hard for us to have a rope 

long enough with knots in it to determine our speed by counting how many 

knots are let out in a certain time period.



Jerry (just kidding)

do not archive



Ron Schreck wrote:



 	  Quote: 	
		  



I'm donning my nomex in preparation for the flamers.  Here's my question... Why oh why do RVers continue to use statute miles and MPH?  I am currently on a tour with ten other RV's and we often exchange range and speed while inflight to keep the various flights in order.  I was brought up on knots and nautical miles and it throws me for a loop when we have a few who insist on calling out speeds and ranges in MPH and statute miles.  All military services use knots, commercial airlines use knots, aeronautical charts are scalled based on nautical miles and ATC uses knots.  As far as I can determine, the only reason GA has clung to MPH is because it sounds faster.  Maybe it started with the Mooney 201?  Sounds better to say your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other than the vanity factor, I see no real good reason to use MPH and I would hope that those of you currently building your RV's would consider this when you purchase your airspeed indicator o

 r calibrate your whiz bang EFIS.  



OK... end of rant.  Tell my why not use knots!



Ron Schreck

RV8, "Miss Izzy"

Gold Hill Airpark, NC



on the way to Cody, WY

tedd(at)vansairforce.org
Guest

Posted: Sat Jun 09, 2007 7:32 am Post subject: Knots vs. MPH

 	  Quote: 	
		   OK... end of rant.  Tell my why not use knots!


	


While we're on a unit-of-measure rant, why do we measure fuel in units of

volume instead of weight when we're putting it in an airplane?  The results

that matter (load, range, and endurance) depend on mass, not volume.



Perhaps at one time fuel pumps actually measured volume.  But now the fuel

pumps themselves actually measure mass flow and then convert it to volume using

an assumed density.  So to get your fuel load you have to take this approximate

volume number and convert back to weight using another approximation.  Crazy!



Tedd McHenry

Surrey, BC

do not archive

klwerner(at)comcast.net
Guest

Posted: Sat Jun 09, 2007 7:51 am Post subject: Knots vs. MPH

Bill,

  

 That is knot tru and you know  it!

  

 Diesen Spass bitte nicht  archivieren...

 [quote]   ---

klwerner(at)comcast.net
Guest

Posted: Sat Jun 09, 2007 8:01 am Post subject: Knots vs. MPH

Jerry,

 I always carry a rope with me, as you never know  when you get an opportunity to hang someone with it...

  

 2B or knot 2B 

  	  Quote: 	
		     --> RV-List message posted by: Jerry Springer <jsflyrv(at)verizon.net (jsflyrv(at)verizon.net)>



Because    knots are for boats.  it would be hard for us to have a rope 

long enough    with knots in it to determine our speed by counting how many 

knots are let    out in a certain time period.



Jerry (just kidding)

do not    archive



Ron Schreck wrote:



 	  Quote: 	
		  --> RV-List message posted by:    Ron Schreck <ronschreck(at)windstream.net (ronschreck(at)windstream.net)>



I'm    donning my nomex in preparation for the flamers.  Here's my question...    Why oh why do RVers continue to use statute miles and MPH?  I am    currently on a tour with ten other RV's and we often exchange range and speed    while inflight to keep the various flights in order.  I was brought up on    knots and nautical miles and it throws me for a loop when we have a few who    insist on calling out speeds and ranges in MPH and statute miles.  All    military services use knots, commercial airlines use knots, aeronautical    charts are scalled based on nautical miles and ATC uses knots.  As far as    I can determine, the only reason GA has clung to MPH is because it sounds    faster.  Maybe it started with the Mooney 201?  Sounds better to say    your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other    than the vanity factor, I see no real good reason to use MPH and I would hope    that those of you currently building your RV's would consider this when you    purchase your airspeed indicator!

  o
	


 	  Quote: 	
		   r calibrate your whiz    bang EFIS.  



OK... end of rant.  Tell my why not use    knots!



Ron Schreck

RV8, "Miss Izzy"

Gold Hill    Airpark, NC



on the way to Cody,    WY



     p;          Navigator    href="http://www.matronics.com/Navigator?RV-List">http://www.matronics.nbsp;              available via    href="http://forums.matronics.com">http://forums.matronics.com

_-===================================
	




	
   [quote][b]

klwerner(at)comcast.net
Guest

Posted: Sat Jun 09, 2007 8:03 am Post subject: Knots vs. MPH

Charlie,

 I took my a good 10yrs to get used to  MPH. Don't now make me waste another 10yrs to go back to Km/h.  do not  archive

 [quote]   ---

pitts_pilot(at)bellsouth.
Guest

Posted: Sat Jun 09, 2007 2:39 pm Post subject: Knots vs. MPH

While everyone has different opinions about why, I can only guess:

Ron Schreck wrote:



 	  Quote: 	
		  



I'm donning my nomex in preparation for the flamers.  Here's my question... Why oh why do RVers continue to use statute miles and MPH?



Because their instruments are in miles?
	




 	  Quote: 	
		    I am currently on a tour with ten other RV's and we often exchange range and speed while inflight to keep the various flights in order.  I was brought up on knots and nautical miles and it throws me for a loop when we have a few who insist on calling out speeds and ranges in MPH and statute miles.



I think it boils down to what you're used to and comfortable with, what 
	


instruments you have onboard.



 	  Quote: 	
		    All military services use knots, commercial airlines use knots, aeronautical charts are scalled based on nautical miles

  



Actually aeronautical charts are based on a scale of 1:20 or something like that .... I don't have one handy ..... and has both a nautical and statute scale at the bottom.
	




 	  Quote: 	
		   and ATC uses knots.



This I didn't know.
	




 	  Quote: 	
		    As far as I can determine, the only reason GA has clung to MPH is because it sounds faster.  Maybe it started with the Mooney 201?  Sounds better to say your spam can cruises at 201 MPH, rather that 188 knots (or so).  Other than the vanity factor, I see no real good reason to use MPH and I would hope that those of you currently building your RV's would consider this when you purchase your airspeed indicator or calibrate your whiz bang EFIS.



Marketing probably was a factor ..... and sounds credible.  It's also 
	


what car drivers are comfortable with. I guess it's the same as the 

argument about going metric.



 	  Quote: 	
		  OK... end of rant.  Tell my why not use knots!



I have three airplanes, and the  Grumman and  Pitts have airspeeds 
	


calibrated in MPH.  The Traumahawk, however, came with an A/S calibrated 

in knots.  When our 'group' goes somewhere (usually for food  ) we 

have the same problem.  I( have Anywhere Map so I can switch back and 

forth between MPH and KTS ..... some of the other planes have a GPS 

fixed in MPH but airspeed in KTS .... and some have the reverse.  We 

don't find it a hindrance ..... just that we perceive some A/C closer or 

farther away than they really are!!!  No big deal, since we always wait 

for the stragglers (some have fast airplanes and some have pokers) to 

arrive anyway.   So, no flames from me ..... but if that's the only 

frustration you have when flying as a group .... I'd let it go.

Linn

do not archive



 	  Quote: 	
		  

Ron Schreck

RV8, "Miss Izzy"

Gold Hill Airpark, NC



on the way to Cody, WY

Deems Davis

Joined: 09 Jan 2006
Posts: 925

Posted: Sat Jun 09, 2007 2:56 pm Post subject: Knots vs. MPH

I think it has it's roots in the Man himself. go to Van's website and 

check how he/they publish performance specs. One of the 1st things that 

every RV builder wants to know once they are flying is 'how does my 

plane compare to Van's numbers'. So the dialog is set from the get go in 

........ MPH.



Deems Davis # 406

Baffling / Plenum / Engine Stuff

http://deemsrv10.com/

 	  Quote:

n5lp(at)warpdriveonline.c
Guest

Posted: Sat Jun 09, 2007 3:08 pm Post subject: Knots vs. MPH

On Jun 9, 2007, at 4:39 PM, linn Walters wrote:

 	  Quote: 	
		   ...

> and ATC uses knots.

>

 This I didn't know.

..

I always wonder what those using MPH and miles say when they tell ATC  

their position or when ATC asks their speed.  Do they actually go  

through the conversion or do they just give wrong information.  It  

sure seems easier to me to just nautical miles and knots.

Larry Pardue

Carlsbad, NM

RV-6 N441LP Flying

http://n5lp.net

pitts_pilot(at)bellsouth.
Guest

Posted: Sat Jun 09, 2007 3:25 pm Post subject: Knots vs. MPH

I'm a fair-weather pilot and fly direct ..... and not that high either 

.... and I hate to talk to anyone except the guys in my gaggle.  

However, I did ask a tower controller how the difference (MPH/KTS) 

affected their operation, since I flew in/out of some towered airports.  

His reply:  NADA!  Now, this was before widespread use of GPS, so his 

answer may be different now, but he explained the pilots have a real 

problem with being '5 miles out' when they were anywhere from 3 to 7!!!  

Admittedly, the difference becomes greater the farther out you are.

My most recent conversations with a tower guy concerned the difference 

between 'track' and 'heading'.  Same answer, though.  If you get far 

enough off heading .... he'll let you know!!!

Linn

do not archive

Larry Pardue wrote:

 	  Quote: 	

 On Jun 9, 2007, at 4:39 PM, linn Walters wrote:...

>> and ATC uses knots.

>>

> This I didn't know.

 ...

 I always wonder what those using MPH and miles say when they tell ATC  

 their position or when ATC asks their speed.  Do they actually go  

 through the conversion or do they just give wrong information.  It  

 sure seems easier to me to just nautical miles and knots.

 Larry Pardue

 Carlsbad, NM

 RV-6 N441LP Flying

 http://n5lp.net

khorton01(at)rogers.com
Guest

Posted: Sat Jun 09, 2007 5:54 pm Post subject: Knots vs. MPH

On 9 Jun 2007, at 18:39, linn Walters wrote:

 	  Quote: 	

 <pitts_pilot(at)bellsouth.net>

 Ron Schreck wrote:

>  All military services use knots, commercial airlines use knots,  

> aeronautical charts are scalled based on nautical miles

>

 Actually aeronautical charts are based on a scale of 1:20 or  

 something like that .... I don't have one handy ..... and has both  

 a nautical and statute scale at the bottom.

It is a royal pain in the you know what to use the scale at the  

bottom.  But, there are all these longitude lines running N-S, with  

marks for every minute of latitude on them.  And, one nautical mile =  

one minute of latitude, so those marks make a perfect scale, if you  

are using nautical miles.

IFR charts have distances between waypoints, all in nautical miles.

Kevin Horton         RV-8 (finishing kit)

Ottawa, Canada

http://www.kilohotel.com/rv8

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