Anti-stall flow directors - anyone..??
04-25-2020, 07:17 AM
#51
Yes, my interest in your experiments are to see if your deflectors have the potential to increase the control surface authority.
Ailerons and rudder both ususally have what we refer to as " control cross coupling ". This maeans that when a control input is made, you get a secondary unwanted reaction. Rudder is the better example which results in a roll and pitch cross couple along with the desired yaw. The cross couple is not linear and the unwanted couple gets worse with more surface deflection. We attempt to eliminate as much as we can by control surface shape, and placement of the wing and stab but I have yet seen any airplane design completely eliminate the phenomenon. The interest I have here is hopefully some increase in control authority so that less surface deflection can be used, less deflection means less control cross couple and would reduce the amount of electronic mixing required to get that true flying airplane.
Ailerons and rudder both ususally have what we refer to as " control cross coupling ". This maeans that when a control input is made, you get a secondary unwanted reaction. Rudder is the better example which results in a roll and pitch cross couple along with the desired yaw. The cross couple is not linear and the unwanted couple gets worse with more surface deflection. We attempt to eliminate as much as we can by control surface shape, and placement of the wing and stab but I have yet seen any airplane design completely eliminate the phenomenon. The interest I have here is hopefully some increase in control authority so that less surface deflection can be used, less deflection means less control cross couple and would reduce the amount of electronic mixing required to get that true flying airplane.
04-26-2020, 01:47 PM
#52
It seems like the conventional wingtip plates we see often would serve exactly the same purpose, by keeping the flow from spilling laterally over the tip. One sees "strakes" also on many wings, probably intended to help aileron effectiveness.
05-01-2020, 05:26 AM
#53
No, I did not - but to be honest I did not really pay attention to aileron authority. Sorry, will keep that in mind for next flights. I plan to pick a good calm day and consider a flying programme like this:
1) Fly around with all 4 baffles and do all the different tricks and figures for a while.
2) Remove outer baffles and fly again as above.
3) Remove also inner baffles and fly again as above.
I will try to retain the c.of g. in the same spot throughout with some lead taped to the fuselage.
Please have your viewpoint on the above...Thank You....Cheers/
1) Fly around with all 4 baffles and do all the different tricks and figures for a while.
2) Remove outer baffles and fly again as above.
3) Remove also inner baffles and fly again as above.
I will try to retain the c.of g. in the same spot throughout with some lead taped to the fuselage.
Please have your viewpoint on the above...Thank You....Cheers/
It is great you are enjoying the experimentation!
The reason why the ones you installed on the tips did not improved stall is because on rectangular platform wings the stall or the airflow boundary layer separates first at the wing root and progress torwards the tip, this is why it worked on the fuselage, but you are already in a stall before it reaches the tip.
Adding turbulators will actually have an even greater effect as it increases the energy of the airflow over the rest of the wing, specially ailerons.
