Effects of wing incidence?

[MaverickSawyer]

I've noticed that tilting a wing pulls the Center of Lift icon towards the wing in question. However, is it going to create more than just a change in the center of lift, i.e. a severe pitch moment if done on a canard?

Edited August 7, 2015 by MaverickSawyer

[Tank Buddy]

Adding an angle of incidence will shift your CoM and it will add torquing force if you have too steep an angle. (essentially moving the CoM far from the CoL.)

Angle of incidence pretty much allows you to have a different AoA than what your current attitude would permit.

[Goddess Bhavani]

A variable incidence wing can help with low speed approach and control, see F-8 Crusader.

Tilting the tailplanes or wings of a craft can also help to maintain a proper trim angle for certain configurations that would be 'uncontrollable' at zero incidence.

It can also be used to affect the flight attitude of a craft - Fw-190 for instance had a famous nose-down flying attitude due to angle of incidence. This gives better visibility from the cockpit, as otherwise some frontal view would be 'blocked' if flying at positive angles of attack.

I also change the incidence to ensure proper positioning of CoL for a given payload rating. (Yes this ship is unstable for a reason - I need the CoL right there both for STOL performance, and to allow this design to cruise at 15,000m close to Mach 3.0 to match original source material)

Notice the wings have a slight negative angle of incidence. This is because I am maximizing body lift as the wings are extremely short! The F-35 has stubby wings and a blended wing design, so does this (somewhat!)

If you look very closely there is a set of very small basic fins mounted on the nose. They have a large positive angle of incidence to optimize airflow and supersonic trim.

Edited August 7, 2015 by pandoras kitten

[ajburges]

I've noticed that tilting a wing pulls the Center of Lift icon towards the wing in question. However, is it going to create more than just a change in the center of lift, i.e. a severe pitch moment if done on a canard?

If most of your lifting surfaces have the same incidence you should have a craft that's just as predictable. Be careful of Mk2 fuselages though.

Lift surfaces only generate lift force if they have an AoA to prograde. Wing incidence increases AoA which increases lift. However, since it has a greater AoA than other surfaces, it will also stall earlier. Furthermore, since it has a different AoA than other surfaces, CoL will migrate depending on craft AoA! In fact, migrating CoL is one way to visualize how control surfaces give control authority.

[Chaos_Klaus]

If most of your lifting surfaces have the same incidence you should have a craft that's just as predictable.

I would argue that. When building an airliner in KSP, I usually add some positive incidence to the main wing to get more lift from that wing while cruising. By default, the aircraft will want to pitch down now. To counter act this torque, I usually have to add some negative incidence to the tailplane. That doesn't cost me much in terms of lift (because the wing area of the tailplan is small compared to the main wing) but makes the craft fly straight at its desinged cruising speed.

When you are not going at cruising speed, it will still want pitch a little but not as bad as if I only add incidence to the main wing.

[CaptainTurbomuffin]

The current CoL is fake. Just don't look at it, until it's written in the devnotes that they fixed it. After the new aerodynamic system was added, it's still showing the CoL of the old system.

[Val]

I mount all my wings and control surfaces with Incidence. In my experience it reduces drag by a lot, which means I can use less engines and less wing area, which in turn means more payload to orbit.

The current CoL is fake. Just don't look at it, until it's written in the devnotes that they fixed it. After the new aerodynamic system was added, it's still showing the CoL of the old system.

Hmm. It seems to work well enough, for me. I used it a lot the past few days, when I built these and others.

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Both of them are also built with Angle of Incidence, which you can kinda see in some of the pictures.

[Goddess Bhavani]

I would argue that. When building an airliner in KSP, I usually add some positive incidence to the main wing to get more lift from that wing while cruising. By default, the aircraft will want to pitch down now. To counter act this torque, I usually have to add some negative incidence to the tailplane. That doesn't cost me much in terms of lift (because the wing area of the tailplan is small compared to the main wing) but makes the craft fly straight at its desinged cruising speed.

When you are not going at cruising speed, it will still want pitch a little but not as bad as if I only add incidence to the main wing.

It's nice to see someone optimize subsonic planes like I do. Without positive incidence, a lot of subsonic designs with higher wing loadings require excessive elevator trim to maintain cruise attitude. They also look silly flying at excessive angles of attack and incur a drag penalty that way.

Positive incidence wings ftw

[Ripper2900]

Lol, that big one reminds me of the Caspian Sea Monster. http://www.australianhovercraft.com/images/gef_caspian_monster.jpg

[MaverickSawyer]

Okay, so it seems like there's a consensus that incidence works like it does in real life. Good to know.