Vertical Stab Fences for 2M F3A Aircraft by grotto2

Last crawled date: 3 years, 1 month ago

An alternative to the T-Canalyzer, these fences straighten airflow over the fin to improve knife-edge flight so important in modern FAI aerobatic sequences. Research by Voicu available at http://www.rcuniverse.com/forum/rc-pattern-flying-101/11585841-airflow-visualisation.html
Fences shown here are based on my copies of Voicu's per his photos on above link. Photo shown here is of my BJ Prolog, a slightly older design brought up to modern F3A requirements. Shown aircraft will perform very tight knife-edge loops.
As shown, the fences may fit other 2M BJ pattern aircraft, as his designs are often derivative. Even if they do not fit your plane, they may serve as a reference point for your own variation.
Additional notes:
Four fences total are required, two upper and two lower.
Prints shown are 2mm in thickness, but this could be increased to 3mm if additional stiffness is desired. IMHO, 2mm PLA should work perfectly fine.
Incidence of the fences is identical to that of the horizontal stab.
The tail of each fence ends at the back of the tail post.
Do not modify the fences to wrap around the leading edge of any swept surface. Voicu found that it countered the effectiveness due to induced turbulence. (I know you see this on other planes. Don't fall for it!)
Originals shown here are cut from 1mm fiberglass sheet. If you wish to duplicate them in glass or another material, prints here can serve as templates.
Mine have additional support by slotted brass tubing inserted in holes drilled through the fin. Fences are edge glued with epoxy. My original tests were with cut styrene taped in place before changing to the permanent installation shown.