#### autoreply

##### Well-Known Member

I've made a quick 'n dirty tool to calculate/estimate Flat Plate equivalent Area. It's a great variable to know, because it's the only way to define the drag of an aircraft, independent of anything else.

I picked various numbers, just from the internet. Others were more reliable and actually measured by an independent source.

A couple of things that really stood out:

*The White Lightning has an extremely low quoted number. To me that looks like pure marketing, the lowest-drag 4-ship has twice the (claimed) drag of the lightning.

*The rather low drag of the Mooney 201

*The extremely low drag of the ASH-30. While I already knew that gliders are much more efficient in terms of drag compared to even the most optimized powered aircraft, this is rather astonishing. The 85ft, 1900 lbs, two seat glider has almost exactly the same drag as the Arnold AR-5 which is very small inside and can only hold a single(small) person and limited payload. (The ASH-30 carries 622 lbs if the engine is installed, about 200lbs more without engine). The closest two-seater is the Nemesis NXT, with 50% more drag.

There's also a tab where you can calculate/estimate the FPEA. Either fill in the numbers (in "input" and "direct calculation"), or fill in the air density and prop efficiency and take a look at the data for a reasonable estimate.

Let me know what you think, input is more than welcome.

Edit 13/8/13, updated version with polar-converter and another half a dozen types added.View attachment Flat_Plate_equivalent_V9.xls

I picked various numbers, just from the internet. Others were more reliable and actually measured by an independent source.

A couple of things that really stood out:

*The White Lightning has an extremely low quoted number. To me that looks like pure marketing, the lowest-drag 4-ship has twice the (claimed) drag of the lightning.

*The rather low drag of the Mooney 201

*The extremely low drag of the ASH-30. While I already knew that gliders are much more efficient in terms of drag compared to even the most optimized powered aircraft, this is rather astonishing. The 85ft, 1900 lbs, two seat glider has almost exactly the same drag as the Arnold AR-5 which is very small inside and can only hold a single(small) person and limited payload. (The ASH-30 carries 622 lbs if the engine is installed, about 200lbs more without engine). The closest two-seater is the Nemesis NXT, with 50% more drag.

There's also a tab where you can calculate/estimate the FPEA. Either fill in the numbers (in "input" and "direct calculation"), or fill in the air density and prop efficiency and take a look at the data for a reasonable estimate.

Let me know what you think, input is more than welcome.

Edit 13/8/13, updated version with polar-converter and another half a dozen types added.View attachment Flat_Plate_equivalent_V9.xls

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