Search in
Sort by:

Question Status:

Search help

  • Simple searches use one or more words. Separate the words with spaces (cat dog) to search cat,dog or both. Separate the words with plus signs (cat +dog) to search for items that may contain cat but must contain dog.
  • You can further refine your search on the search results page, where you can search by keywords, author, topic. These can be combined with each other. Examples
    • cat dog --matches anything with cat,dog or both
    • cat +dog --searches for cat +dog where dog is a mandatory term
    • cat -dog -- searches for cat excluding any result containing dog
    • [cats] —will restrict your search to results with topic named "cats"
    • [cats] [dogs] —will restrict your search to results with both topics, "cats", and "dogs"

VehicleMovement Drag Force wrong direction

VehicleMovementComponent -> Drag Force Parameter

The drag force should simulate air drag force and slow the car down at high speeds

Bug: The Drag force is not applied on a local vector of the car [-X], but on a world axis [-X]. This leads to drifting while driving parallel to the world [Y] axis, or crazy accelleration while driving in world[-X] direction.

Notice: This effect can only be seen with fast moving cars, or cars of extreme low mass. I myself needed 3hours to figure out why my car was drifting always in world[-X] while driving on ice (low tire fraction)

How to repruduce:

  1. Create a WheeledVehicle BP

  2. Import a car, set everything up (the car from the content packs will work too, if they use a vehiclemovementcomponent)

  3. Change the mass inside the VehicleMovementComponent to a low value like 10kg. This will make sure, you can see the effect. You might also set the tire friction a little lower like 0.4

  4. Make sure VehicleMovementComponent->"Drag Force" <>0 (higher values work better)

  5. Auto Posses Player 0 in game, drag car into a level.

  6. Play the game. Align car to World Y-Axis and speed up. The faster the car goes, the more it will be dragged to World [-X] Axis.

  7. If you can't reproduce, build a little ramp aligned World Y-Axis. The Tire Friction may cause the issue. If no tires are on the ground or the front wheels lift a little when going full throttle, the effect will be seen much better.

best regards, Tank

Product Version: UE 4.18
more ▼

asked Feb 12 '18 at 03:19 AM in Bug Reports

avatar image

241 12 13 26

avatar image Sean L ♦♦ STAFF Feb 12 '18 at 12:36 PM


We've recently made a switch to a new bug reporting method using a more structured form. Please visit the link below for more details and report the issue using the new Bug Submission Form. Feel free to continue to use this thread for community discussion around the issue.



(comments are locked)
10|2000 characters needed characters left
Viewable by all users

1 answer: sort voted first

Sorry, the value is called "Drag Coefficent" and not "Drag Force". You can find it:

VehicleMovementComponent->VehicleSetup->Drag Coefficent

more ▼

answered Feb 12 '18 at 03:22 AM

avatar image

241 12 13 26

(comments are locked)
10|2000 characters needed characters left
Viewable by all users
Your answer
toggle preview:

Up to 5 attachments (including images) can be used with a maximum of 5.2 MB each and 5.2 MB total.

Follow this question

Once you sign in you will be able to subscribe for any updates here

Answers to this question