Replace Winglets with Vertical Tail for Canard

[rnordquest]

All the old books for aircraft design are basically for a forward wing aft tail arrangement. How do I calculate the tail size and power for a canard?

The original aircraft has only winglets. What I want to do is remove the winglets and replace them with a single vertical tail.

Roger

 

[Peyto193]

I am not positive, but I have been using Jan Roskam's texts on Aircraft Design in my prelim design class. It's a 9 part series and I'm wondering if any of the books have that information. If you haven't already, I would suggest taking a look at that. Hope that helps

Chester

 

[rnordquest]

I wish I had a copy of Roskam's books but I don't. Maybe the local university library. I'll try that after Thanksgiving.

 

[JohnFortier]

Have you considered that the removal of the winglets might produce tip vortices which might in turn induce flutter at a fairly low airspeed?

I'd check into why the winglets were used in the first place before making this mod.

Cheers

John

 

[tmoritz]

Make sure the vertical stabilizers and rudder have a long enough moment arm to counter adverse yaw and damp any yaw oscillations. If I recall correctly you will need to sweep aft wing to achieve this. Now you have to design a bent wing spar and because the spar intersection with the fuselage has moved forward you may have the spar intruding into space you allocated for the pilot, crew, cargo, etc. Just some thoughts. You may want to take a look at some of Rutan's earlier designs, the LongEZ comes to mind.

 

[rnordquest]

I'm not going to completely remove the winglets, just reduce their size and take away their yaw control. The aft wing is already swept, it's a Velocity.

 

[tmoritz]

Whoops, I got it backwards. I thought you were removing a vertical stab and replacing it with winglets with rudder tabs.

Yaw stability is basically the same for canard and conventional aircraft. It's been a while since I did aircraft stability calculations but if I recall correctly dynamics are an issue of the lateral lift and yawing moment generated by a side slipping fuselage, the righting moment generated by the vertical stab/rudder, and the yaw moment of inertial of the aircraft. I don't think the wing configuration changes anything in this equation other than minor changes to the yaw moment of inertia. Static stability either. You should be able to calculate the aircraft yaw dynamics using those old texts.