Canard Lift too high ?

[Pillow]

Hello,

for quite some time I've been wondering if I don't get the concept of center of lift... As far as I know a plane ist balanced if the center of lift and the center of gravity match. Ideally the COL should be placed behind the COG for the plane to be inherently stable but here's the problem:

Eyerytime I start building a plane with a tailplane that consists of canards the COL is extremely far behind COG even if I add fairly big main wings. It seems to me as if the lift rating of the canards was way too high for their size. Am I misunderstanding something here or does anybody else draw the same conclusions ?

I appreciate every helpful answer.

Pillow

 

Edited December 1, 2015 by Pillow
no image

[Boris-Barboris]

Editor CoL vector is a lift force, applied to your craft at 1-degree angle of attack. Your case is a clear sign of non-horizontal orientation of canards - they have positive base AoA. Rotate them carefully and you'll find the truth, or use different tail-peace, straight one, for surface-attached canards to be strongly horizontal.

[Claw]

It looks like you have a bit of rotation on the tail. Rotating wings or control surfaces will cause higher effective lift for that part, which will move the CoL around. In this case, looks like the tail has a bit of AoA, giving it slightly more effective lift, which moves the CoL back.

Edited December 2, 2015 by Claw

[Pillow]

Ok so I was tricked into thinking that the angle snap option would make the canards have zero AOA.

Thanks for your answers guys !

[AeroGav]

Another victim of SPH gotchas !  Yep, over time you learn not to try attaching certain combos of parts, because even though they look like they should work , they don't hook on straight and leave you with a messed up aircraft.   Attaching radially to anything other than a cylindrical aircraft fuselage (type 1, 2, or 3) barrel is high risk.    Furthermore the fuselage pieces you attach to should be the same at both ends, and not tapering lengthwise

Safe

rocket/liquid/mono fuel fuselage short/long

structural fuselage

inline cockpits

service bays, cargo bays, inline docking ports

Unsafe (risk of subtle misaligns and you wasting the next three hours of your life)

Adapters (tapering sections to join a type 2 to type 1 or type 3)

Nose/Tailcones

non-inline cockpits

[Claw]

AeroGav has a pretty good rule of thumb. If the part is sloped or curved, it will probably have "non-square" default attachments.

In those cases, it often helps to turn angle snap OFF and then adjust the part (with either WASD or the gizmos).

[SpaceplaneAddict]

The further away a wing/canard is from the CoG, the more effect it will have on the CoL. Your main wings are close to the CoM, so they have minimal effect. The canards are wayyyy further down the plane, you they have an increased effect on the CoL. However, they will still produce the same lift force.