How does Cessna gather performance numbers?

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12-29-2009, 02:36 PM

withthatsaid182

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How does Cessna gather performance numbers?

Looking at the Cessna 172 manual they have a number of charts for takeoff distances.

How do they go about getting those take off distance numbers?

Is it all done with a math equation? Do they actually test the distances and convert it somehow for a standard day?

12-29-2009, 03:11 PM

Ewfflyer

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I would assume they have to do several actual demonstrations, and then I believe they make all the corrections mathmatically to "standard day" conditions for a base-line of all performance charts.

With the knowledge today, they have a really good idea on how a plane will perform, but until you put it to the test, you can't prove anything with just the numbers.

12-29-2009, 06:15 PM

ryan1234

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If you are wondering about the test pilot workings and reports. There is a website where you can download the Naval Test Pilot School Fixed Wing Performance Flight Test Manual (long name). I don't know of the website address off the top of my head. I was lucky enough to have gotten a hard copy of the manual (a bit of a nerd) and it's really, really interesting for people who wonder where those POH type numbers come from and the limitations of those numbers.

12-29-2009, 10:12 PM

shdw

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Quote:

Originally Posted by ryan1234

Naval Test Pilot School Fixed Wing Performance Flight Test Manual \

I spent some time searching for this, to no avail. However, Ryan, if you do happen to locate a link I would very much enjoy the read.

Thanks,

~Brian

12-30-2009, 06:54 PM

ryan1234

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Quote:

Originally Posted by shdw

I spent some time searching for this, to no avail. However, Ryan, if you do happen to locate a link I would very much enjoy the read.

Thanks,

~Brian

Here ya go
Library

btw where are you based outta Brian?

12-30-2009, 07:45 PM

shdw

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Quote:

Originally Posted by ryan1234

Here ya go
Library

btw where are you based outta Brian?

Thank you

Bridgewater NJ. Currently one of the many unemployed, so no airport base. Keeping my mind in the game writing this private pilot curriculum. Site is actually up now, but full launch isn't for a few weeks. I don't think I can post it publicly here though, something about their advertisement policies.

Edit: Where are you based Ryan?

Last edited by shdw; 12-30-2009 at 10:16 PM.

12-31-2009, 11:40 AM

Cubdriver

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Quote:

Originally Posted by withthatsaid182

Looking at the Cessna 172 manual they have a number of charts for takeoff distances...How do they go about getting those take off distance numbers?...Is it all done with a math equation? Do they actually test the distances and convert it somehow for a standard day?...

I worked until recently in the flight test department of a major bizjet manufacturer doing this very thing. We used calculation for minor airframe alterations, and we used real flight testing for initial certification on new aircraft designs. The calculation algorithms used to get performance numbers must themselves be FAA certified, or more accurately there is an FAA-authorized rep on the company payroll called a Designated Engineering Representative (DER) doing this. But the results are gospel, and the use of calculation permits comprehensive performance documentation to be produced for any given aircraft. The older piston airplane performance numbers were approved before my time in industry and before computers in most cases, so I can't speak to that without asking around.

Great link, Ryan.