How do I enable simulate physics? It's greyed out

I’m starting out with Unreal and using the Flying Blueprint.

I am trying to enable the simulate physics, it seems to be greyed out and unselectable.

I read somewhere that collisions had to be set up, so I enter the static mesh options of the UFO and in the collisions drop down menu I select Add 26DOP Simplified Collision and click Save but still the simulate physics is greyed out and unselectable. I also went into the mesh options of the UFO and clicked on the big collisions button and checked simple collision and hit save, but none the less the simulate physics is still unselectable.

I am still not sure if the collision options I am choosing are being saved, because when I go into the static mesh options of the UFO the simple collisions is not checked…
So I don’t know what I’m doing wrong… :confused:

What you need is a Physics asset for your skeletal mesh (UFO) in order for the simulate physics to available.(Different than it’s collision object)

You can create one by right clicking the skeletal mesh asset in the content browser and go to Create / Physics Asset / Create and Assign. That should enable the simulate option within the character blueprint.


What if I have collision enabled and a working phat (Physics Asset) and the button is still greyed out? The simulation in phat works beautifully but not anywhere else. I am trying to simulate physics on a skeletal mesh component hair armature added on to the main actor. I’ve tried everything…

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did you ever find the solution to this?

Had the same issue. Open the skeletal mesh - and set the physics asset for it. Sometimes in the project, you have skeletal meshes and physics assets. and it IS a physics asset for this skeletal mesh - but it’s not set as being in use. Cant be done on blueprint level - only in the skeletal mesh asset details.


What does one do, if this is a static mesh , in a bp, in my case for a BP created Rope ( cable component) ? NO matter what I do, I can’t find a way to un-grey physics > simulate physics , for the static mesh, that is the ‘seat’ at bottom of rope player will sit on for gameplay, etc.

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People are funny, the man ask a solution for a STATIC mesh but everyone here just give him the solution for the skeletal mesh…


Just give StaticMeshComponent a static mesh, then you can enable simulate physics.

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Hi, I had same issue and found that the static mesh needed a collision body adding before Simulate Physics was selectable. Open the Static Mesh > Collision > add Box Simplified Collision (or any collision depending on what you need) and that should be it. Well, it was for me anyway, hope this helps.


Hey I found the solution. Simply double click open the STATIC MESH it self, and there is a collision drop down tab (UE5), click and add simple collision. Now you can stimulate physics.


That’s the way thanks and happy new year 2023

Idk if you already found a solution to your case, but I had the same issue.

In my specific case the blueprint actor I was using for some reason ! didn’t have a mass ! and thus physics could not be simulated (which kinda makes sense when you think about it).

I had this piece of paper, which is just a 2D object.

Since all materials are one sided (backface culling) by default in most 3D programs, I changed the material to “Two Sided” for the material of my static mesh. I changed a bunch of other stuff and I seriously doubt that that was the reason why it suddenly didn’t allow me to tick “Simulate Physics”, but there you go.

I then noticed that when I clicked on the Static Mesh component of my Actor Blueprint, that it had no Mass.

So I clicked on Mass and set it to 0.01 kg. Thanks to that, simulate physics was no longer greyed out.

The weird thing is that once I unchecked mass again, Simulate Physics was still set to true.

Frankly, I am as confused as you as I type this, since I though it was the mass that was the problem, but now I realised that I can set simulate physics regardless. But I’m pretty sure that was what I changed before it started working again. This is for sure weird.

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Thanks Dude Works on me. UE5.0.3

Thx that was it!! ;0-0 gez so odd though ,player was already able to step onit, so coll was working.

I know is late to answer but maybe be good for someone need answer now.
all you need is add Collison to static mesh by double click on it, and select collision from top menu and then select add sample box collision and save. DONE

question. i spawn an object that is socketed to a mesh (player skel) the spawned blueprint doesnt have collision on it. it is a shield that spawns infront of the actor and followa thw actor when they move. i dont understand why the shield doesnt have its own collision when spawned. i have made a simple collision for it in the static mesh asset. please help. thank you.

Hi ! Thank you so much ! I was really lost !