Is this a good place to have the Center of Thrust?

[Andrew1233]

Hi guys! I made a new commercial airliner using 100% stock parts, but I just want to make sure if this is a good place to the the Center of Thrust: https://imgur.com/a/yA82eMy

Or maybe other problems of the aircraft that can be seen in SPH, thanks for any help!

oh wait i just find out that it will have nose down is because of timewarp, the nose goes back normal when I stopped time warping. 

Edited April 12 by Andrew1233

[Vanamonde]

It looks reasonable to me. By being slightly under the COM it will provide a bit of nose-up torque. This can be useful as long as the over-all mass distribution is slightly nose-down for stability. 

[Andrew1233]

9 minutes ago, Vanamonde said:

It looks reasonable to me. By being slightly under the COM it will provide a bit of nose-up torque. This can be useful as long as the over-all mass distribution is slightly nose-down for stability. 

ahh yes, tho during long flights this plane just have a slight nose down, making it hard for higher altitude than 5000 meters, and I always have to use the elevon on the tail horizontal tail and press deploy to keep it nose up, but then it just stalled and nose down again lol Idk why it just cant get stable 

[Aelfhe1m]

Try giving the main wings a small angle of incidence (use the rotate tool to tilt the front edge of the wings up about 5°). You get lift in KSP based on the angle between your wing surface and direction of flight. By pre-tilting the wings you get a little extra lift while holding the main body more horizontal which decreases overall drag (unless your wings are huge).

Note: after applying angle of incidence you may need to move the wings back or forward to maintain relative CoM and CoL.

Most of the fuel looks like it's in tanks towards the rear of the plane which is why it gets nose heavy later in flight. Which wings are you using? Can they store fuel? That can help keep the CoM more stable as fuel drains.

Deploying flaps acts as a brake, which is why you are stalling. Instead you can use advanced tweakables to increase the control authority on the elevons.

Also make sure that each of your control surfaces is only responsible for one axis of rotation (usually). Pitch on the rear elevons, yaw on the tail rudder, and roll on the wing elevons. Also, despite looking a bit out of place on a passenger jet like this, canards at the front can also help if the plane needs extra pitch authority.

[Andrew1233]

1 hour ago, Aelfhe1m said:

Try giving the main wings a small angle of incidence (use the rotate tool to tilt the front edge of the wings up about 5°). You get lift in KSP based on the angle between your wing surface and direction of flight. By pre-tilting the wings you get a little extra lift while holding the main body more horizontal which decreases overall drag (unless your wings are huge).

Note: after applying angle of incidence you may need to move the wings back or forward to maintain relative CoM and CoL.

Most of the fuel looks like it's in tanks towards the rear of the plane which is why it gets nose heavy later in flight. Which wings are you using? Can they store fuel? That can help keep the CoM more stable as fuel drains.

Deploying flaps acts as a brake, which is why you are stalling. Instead you can use advanced tweakables to increase the control authority on the elevons.

Also make sure that each of your control surfaces is only responsible for one axis of rotation (usually). Pitch on the rear elevons, yaw on the tail rudder, and roll on the wing elevons. Also, despite looking a bit out of place on a passenger jet like this, canards at the front can also help if the plane needs extra pitch authority.

well, I actually dont have any fuel on the back, I put all my fuel in the wings, i use the big delta wing and the FAT-455 wing that can both put fuel in, I also added 3 more Mk1 Liquid Fuel Fuselage between the wings and the center of the aircraft. and i just find out that it will have nose down is because of timewarp, the nose goes back normal when I stopped time warping. 

1 hour ago, Vanamonde said:

It looks reasonable to me. By being slightly under the COM it will provide a bit of nose-up torque. This can be useful as long as the over-all mass distribution is slightly nose-down for stability. 

i just find out that it will have nose down is because of timewarp, the nose goes back normal when I stopped time warping lol