Author Topic: The Tale of Tails  (Read 6677 times)

PonoBill

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Re: The Tale of Tails
« Reply #30 on: December 15, 2022, 11:42:26 AM »

Do you reckon James Casey is using the new Axis 400 Flat Speed Carbon Rear Wing?


New? I've been using the 400/60 for more than a year. I love the thing.
Foote 10'4X34", SIC 17.5 V1 hollow and an EPS one in Hood River. Foote 9'0" x 31", L41 8'8", 18' Speedboard, etc. etc.

Beasho

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Re: The Tale of Tails
« Reply #31 on: December 15, 2022, 12:04:43 PM »
I have posted something similar before but this is pretty critical.  This NASA calculator is awesome.  It will simulate a straight wing generated from any foil section.  Be sure to change it to water and leave depth at zero. 

https://www1.grc.nasa.gov/beginners-gui
 

This is pretty cool.


I am playing with the inputs for the front wing, and making the wing as small as possible.  5 feet is the shortest span.  Then go to chord = 0.5 feet to get an Aspect ratio of 10:1.  This is close to the 1099 @ 10.6.  Reynolds number comes into play here. 

The area though is 2.5 square feet.  This is near to 2X the 1099, but in water and getting all the metrics sync'd up.  It shows lift of 600 lbs at ZERO degrees assuming SOME camber.  I am not sure what the thickness % is but varying that input didn't change the lift very much.

Net result is 604 lbs of lift.  Near to the 260 X 2 I have been using.  I suspect there is LESS camber on the Axis 1099 but the conclusion is that in steady state the 1099 is likely flying at near ZERO degrees.  BUT Camber is a huge input and would take lift down to ZERO at 0%. 

Lift to Drag Ratios are also close to my assumptions (18 vs 16).
« Last Edit: December 15, 2022, 12:06:40 PM by Beasho »

Admin

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Re: The Tale of Tails
« Reply #32 on: December 16, 2022, 12:56:49 AM »
Very cool. 

https://www.ecalc.ch/wingdesigner.htm

This center of gravity calculator is super valuable as well.  Elements such as sweep (and static margin) alone can easily change center of gravity in commonly used wing shapes by 3 inches (in a game of millimeters).   


This is why complete foil systems need to be so intentional and purpose built.  It has me hyper focused on a targeted take off condition and an at-speed range for each use type.  There is a lot left to be discovered.

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Re: The Tale of Tails
« Reply #33 on: December 16, 2022, 01:12:36 AM »
I have posted something similar before but this is pretty critical.  This NASA calculator is awesome.  It will simulate a straight wing generated from any foil section.  Be sure to change it to water and leave depth at zero. 

https://www1.grc.nasa.gov/beginners-gui
 

This is pretty cool.


I am playing with the inputs for the front wing, and making the wing as small as possible.  5 feet is the shortest span.  Then go to chord = 0.5 feet to get an Aspect ratio of 10:1.  This is close to the 1099 @ 10.6.  Reynolds number comes into play here. 

The area though is 2.5 square feet.  This is near to 2X the 1099, but in water and getting all the metrics sync'd up.  It shows lift of 600 lbs at ZERO degrees assuming SOME camber.  I am not sure what the thickness % is but varying that input didn't change the lift very much.

Net result is 604 lbs of lift.  Near to the 260 X 2 I have been using.  I suspect there is LESS camber on the Axis 1099 but the conclusion is that in steady state the 1099 is likely flying at near ZERO degrees.  BUT Camber is a huge input and would take lift down to ZERO at 0%. 

Lift to Drag Ratios are also close to my assumptions (18 vs 16).

It is also a great quick reference for comparing potential design changes such as chord length vs wing angle to achieve a specific design goal.

 


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