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Airspeed Indicator - MPH vs Knots Questions

Sparky

Sparky

Well Known Member
I will be installing a steam gauge airspeed indicator (as a backup) in my RV-7 and have a few simple questions. Should it indicate in MPH or Knots? What are the advantages or disadvantages of each? If I install a dual scale airspeed indicator, which is "best" for the outer scale? Is there a "defacto standard"? Does it really matter? I'm a pretty low time pilot, so I'm really not partial to one or the other at this point, so personal preference isn't an issue for me. What did you choose and why?
 
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I went with an true airspeed indicator with the outer ring in mph and the inner in knots. Why limit yourself?
 
It's all personal opinion. I like knots & my buddy prefers MPH (maybe 'cause it makes it look like it's going faster). I have a dual scale with mph on the inside

L.Adamson
 
Everything you talk to a controller about will be in knots and nautical miles. Flight plans are filed in the same. MPH is a more impressive number but in oreder to reduce the confusion, I went with a knots only AS.

All in all, like already said, it is strictly personal preference. The only thing I would not do would be a MPH only AS.
 
Knots

For basic VFR flying "it don't make no never mind." However, the FAA and ATC do business in Knots. IFR charts are in nautical miles. My opinion is that it should be in knots. In the case of a dual scale indicator, I would put knots on the outside for the above reasons. I'm sure that some of it comes down to marketing, when you are selling kits 200 miles per hour is more impressive than 174 knots.

John Clark
RV8 N18U "Sunshine"
KSBA
 
Distances - how you measure...

The FAA standardized in knots in the late 70's on certified planes.

But in our applications....

It may depend on which scale you use when you look at sectionals...:)

If you use the NM scale, then fly in knots (knots == nm per hr)... if you like to use statute miles on your maps... then fly in mph...

gil A

Flying in kts, which the sailplane guys sort of standardized on, variometers do not come in mph vertical speed....:)
 
Go with km/h

az_gila said:
It may depend on which scale you use when you look at sectionals...:)
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I don't look at the scale on the sectionals. I look at the minute marks on the lines of longitude - one minute of latitude = 1 nm.

If you ever talk with ATC, or use aviation maps, knots are the way to go. If you want big airspeed numbers to impress your friends, go with km/h - most RVs should be able to do more than 300 km/h IAS at low altitude - sounds fast to me ...:)
 
KaNots are the way to go.

Like Kevin, I have been using minutes of longitude, and a pair of dividers since before I soloed, but then I have always used hours and minutes not tenths. AltonD and John are correct kts are the official standard, that's the way to go. IMHO.
 
Thanks for the input

I appreciate all the replies. I was planning on a dual scale indicator with knots on the outer scale so the majority opinion reinforces my original plan. Thanks.
 
I could be wrong but shouldn't you guys be using minutes of latitude, unless you do all your flying on the equator.
 
Oopsee

Good catch jt, Kevin was right, I twisted abit. Minutes of latitude, the tick marks on the lines of longitude...that's the ticket.:eek:
 
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