ConstantSpeed.cs

using UnityEngine;

[AddComponentMenu("Liberi/Constant Speed")]
[RequireComponent(typeof(Rigidbody))]
[Script(ScriptRole.Owner)]
public class ConstantSpeed: MonoBehaviour
{
    public float Speed;

    void OnSpawn (UJeli details)
    {
        if (details.HasChild("Velocity"))
            Speed = details["Velocity"].Vector3Value.magnitude;
    }

    void FixedUpdate ()
    {
        if (rigidbody.isKinematic)
            return;

        rigidbody.velocity = rigidbody.velocity.normalized * Speed;
    }
}