Hello Paul,

Yesterday I met Christian Hugues, developer of Minix winglets.
Those winglets have shown reduction of induced drag of 18% on wing and
thus about 6% on total plane drag.

See video of principle on http://www.minix.fr/video_minix_swf.htm
Prototype on a plane is currently being installed in the UK.
French site is complete : www.minix.fr
English site not complete yet : http://www.minix.fr/english/index.php

I think you might be excited to see this. Any interest of using those?


Best regards,

Randolph in Paris

That is very interesting. Reducing induced drag has been the holy grail aero
engineers for decades.

Paul Lamar

Paul,

This is very interesting.  I have been searching for an alternative
wingtip for my SeaWind since I extended the wing and copied a friend's
fold-up sponson design.

Would there be any advantage to having them up the T- tail stabilizer as
well.

Doug in Japan

They only pay off when the lift coefficient is very high and the airplane is not climbing.  They pay off at high altitude when the aircraft is near stall in the so called coffin corner. During climb induced drag is a factor but compared to lifting the weight of the aircraft it is a much smaller factor.

If you are climbing at 1200 FPM and your aircraft weighs 3000 pounds that is 20 feet per second straight up or 20 x 3000 or 60,000 pound foot per second divided by 550 or 109 HP just to climb. 128 HP from the engine assuming an 85% eff. prop. The aero drag is near nothing at 100 MPH climb speed. If you get the flat plate equivalent down to 4 than you have 100 pounds of drag, not counting induced drag due to lift, going at 150 feet per second or 32 prop HP. Now the induced drag coef. is  C sub L squared over pi times the aspect ratio. Here is where the special wing tips come into play. In effect they improve the aspect ratio somewhat.

Here are some charts from one of my favorite books.

Practical Guide to Airplane Performance and Design by Donald H. Crawford 1981 ISBN 0-9603934-0-4

Paul Lamar