# Best rate of climb, how does the pilot know?



## pbehn (Jan 13, 2018)

In WWII BoB the Spitfire and Hurricane had identical engines and propellers but different airframes. Their maximum rate of climb was achieved at different forward speeds and angles of attack. Bearing in mind that the performance of the engine and propeller changed with altitude as did the wing how did the pilot know he was getting the best climb performance. Was it a forward speed or angle of attack at a certain altitude or just a "feeling" holding the plane on the edge of stall *hanging on the propeller".


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## Greyman (Jan 14, 2018)

It (EDIT: Best Climb Speed) is generally a well-known figure among pilots. The speed is figured out when the aircraft is being tested and makes it into the manuals/pilot's notes/etc.

It would be easy enough to test. Change your speed +/- 10 mph in a climb and see if the rest of your section ends up above or below you. Or just watch the climb rate indicator


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## swampyankee (Jan 14, 2018)

pbehn said:


> In WWII BoB the Spitfire and Hurricane had identical engines and propellers but different airframes. Their maximum rate of climb was achieved at different forward speeds and angles of attack. Bearing in mind that the performance of the engine and propeller changed with altitude as did the wing how did the pilot know he was getting the best climb performance. Was it a forward speed or angle of attack at a certain altitude or just a "feeling" holding the plane on the edge of stall *hanging on the propeller".




1) Engineers can determine the aircraft's power requirement vs angle of attack. and usable power available. The power left over determines rate of climb.

2) Flight testing includes a systematic investigation into the aircraft's performance.

Modern analytical methods -- CFD -- has changed 1 from "this is about where it should be" to "this is where it will be" and 2 from "let's search for it, somewhere in this area" to "yep, they were right."

Both these result in the service pilot getting this information in the aircraft manual. After that, it's a matter of proper pilot training and flight planning.


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## AMCKen (Jan 18, 2018)

Back in the 1970s when I was flying a Cessna 150, I noticed the best climb rate speed and either the best glide speed or most economical speed were nearly the same. Probably a 'sweet spot' in the power/drag/weight graphs.

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## XBe02Drvr (Jan 18, 2018)

AMCKen said:


> Back in the 1970s when I was flying a Cessna 150, I noticed the best climb rate speed and either the best glide speed or most economical speed were nearly the same. Probably a 'sweet spot' in the power/drag/weight graphs.


It's all about optimum lift over drag or L/D speed. That's the point where the airframe is at its peak efficiency, thrust available exceeds thrust required by the greatest amount, and the airframe achieves it's best glide ratio; the "sweet spot" as you so rightly called it.
Cheers,
Wes


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## Barrett (Jan 19, 2018)

Updating the topic (!). In 1985 during my F-15 demo flight, there was an audible tone when the Eagle made optimum turning (cornering) speed, c. 300 kts. Didn't think to ask about vertical indicators.


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