1969 Cherokee 140 cruise speed??

Dwayne said:
Some posts here show MPH, others show knots. The outside ring on a 140 indicates miles per hour, the inner ring is knots per hour. So, 110k = 126 mph, 110 mph = 95 k.
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GAMA member manufacturers agreed to standardize on knots in the mid 1970s. Piper switched to knots as the primary scale on the ASI and in the performance charts in 1977, the last year of Cherokee 140 production.
 
Pilawt said:
GAMA member manufacturers agreed to standardize on knots in the mid 1970s. Piper switched to knots as the primary scale on the ASI and in the performance charts in 1977, the last year of Cherokee 140 production.
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Too bad there's not an aviation themed Jeopardy game show to monetize your storehouse of knowledge. "I'll take Lycoming for a $1000"
 
jmarine225 said:
So i'm onto a new thing with this recent purchase. For some reason, it seems as though the airspeed is quite low at cruise at around 2400 rpm. It has the 160hp engine installed in it and no issues with the engine at all, really good compressions. Upon levelling off at cruise altitude it seems the airspeed indicator only shows 90-100 on a good day. Tonights flight, foreflight showed cruise around 110 knots. Air was smooth as glass and the weather reports also didn't provide a 20 know tailwind. Any thoughts on this??
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What speed were you hoping for?
 
Half Fast said:
A "knot" is a nautical mile per hour. Knots per hour would be an acceleration, not a speed.
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Per a true airspeed indicator for my old 140, the outer ring says "M.P.H", the inner ring says "KNOTS".
 
Half Fast said:
Exactly. It says “knots,” not “knots per hour.”
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Seems like a missed opportunity to confuse the Europeans...

"Is this KPH Kilometers per Hour or Knots per Hour?"
 
Half Fast said:
Exactly. It says “knots,” not “knots per hour.”
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My apologies, so it doesn't stand for nautical miles per hour?
I can't believe I had it wrong all these years, especially when I read "knots, or nautical miles per hour, have long been the standard units of velocity for nautical and aeronautical navigation".
So, an indication of " knots" on an airspeed indicator represents what to you?
 
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Dwayne said:
My apologies, so it doesn't stand for nautical miles per hour?
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www.britannica.com

Knot | Knot | Knotting, Tying, Weaving | Britannica

Knot, in navigation, measure of speed at sea, equal to one nautical mile per hour (approximately 1.15 statute miles per hour). Thus, a ship moving at 20 knots is traveling as fast as a land vehicle at about 23 mph (37 km/hr). The term knot derives from its former use as a length measure on ships’
www.britannica.com www.britannica.com
 
2-Bit Speed said:
www.britannica.com

Knot | Knot | Knotting, Tying, Weaving | Britannica

Knot, in navigation, measure of speed at sea, equal to one nautical mile per hour (approximately 1.15 statute miles per hour). Thus, a ship moving at 20 knots is traveling as fast as a land vehicle at about 23 mph (37 km/hr). The term knot derives from its former use as a length measure on ships’
www.britannica.com www.britannica.com
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Thank you.
Even the old Flight Training Manual (Revised 1980) says the airspeed indicator ... "is calibrated to show the pilot the speed of the airplane in statute miles per hour (MPH), or nautical miles per hour (Knots), or both."
 
Dwayne said:
My apologies, so it doesn't stand for nautical miles per hour?
I can't believe I had it wrong all these years, especially when I read "knots, or nautical miles per hour, have long been the standard units of velocity for nautical and aeronautical navigation".
So, an indication of " knots" on an airspeed indicator represents what to you?
Click to expand...

Knots = nautical miles per hour which is speed

Knots per hour (what you originally wrote) = (nautical miles per hour) per hour which is a change in speed, or acceleration

I’ve never seen anyone use “knots per hour.” Just knots.

Here’s what you wrote:
“...the inner ring is knots per hour.”
 
Half Fast said:
Knots = nautical miles per hour which is speed

Knots per hour (what you originally wrote) = (nautical miles per hour) per hour which is a change in speed, or acceleration

I’ve never seen anyone use “knots per hour.” Just knots.

Here’s what you wrote:
“...the inner ring is knots per hour.”
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Where does the "change in speed" apply? If you're cruising at 100 Knots, you're airspeed is a constant 100 nautical miles per hour. No change or acceleration involved.
You must still be in ground school.
 
Dwayne said:
Where does the "change in speed" apply? If you're cruising at 100 Knots, you're airspeed is a constant 100 nautical miles per hour. No change or acceleration involved.
You must still be in ground school.
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:popcorn:
 
Dwayne said:
Where does the "change in speed" apply? If you're cruising at 100 Knots, you're airspeed is a constant 100 nautical miles per hour. No change or acceleration involved.
You must still be in ground school.
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If you’re at 100 knots (100 nautical miles per hour) and over the next hour you increase to 150 knots, you have accelerated at 50 knots per hour.

Knots per hour is a unit of acceleration, not speed. Go re-read your original post.

Guess you never took physics.
 
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