Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Dirtbike trajectory

  1. Jan 27, 2009 #1
    Hi everyone,

    Im new on here, joined in the hopes that someone might be able to assist. Myself and a friend have created a freestyle motocross park, with all kinds of huge jumps. We have just been approached by the owner of an earthmoving company who is going to sponsor us the earthmoving equipment for a 200 foot jump landing. It is now up to me to come up with a design for our landing, so that the sponsor can come and create it for us. For this I need to work out what kind of "launch" angle we will need on the ramp, to put it at the correct distance. I have used the basic trajectory formula to build jumps before, but nothing over 65 foot. I am worried that the drag involved with the speed required to clear 200ft is going to mess with my calculations, can anyone help?

  2. jcsd
  3. Jan 28, 2009 #2


    User Avatar
    Homework Helper

    A 200 foot jump falls into extreme dare devil territory, and those guys have a lot of accidents, in spite of teams of "experts" that know jump physics and do a lot of experiments at shorter distances to gather enough information for progressively longer jumps.
  4. Jan 28, 2009 #3

    Ranger Mike

    User Avatar
    Science Advisor
    Gold Member

    Once againk, Jeff hit the nail on the head...i suggest you look up Darwin Award and save yerself a lot of traction and hospital time experimenting to get it right..option 2 is to add a rocket to the peddler and hang on..

  5. Jan 29, 2009 #4
    Thank you for the reply, but I do not really appreciate the fact that you assume I am some kind of idiot that just go into dangerous activities blindly. I am an engineer as you probably are, my approach to this is a very professional one, as with everything I do. Unlike you I do not only have a brain and use it, but I also have alot of skill when it comes to jumping dirtbikes, so unless you have anything positive to contribute to my original question please keep snide remarks to yourself.

    So I take it no one can help me on this then?
  6. Jan 29, 2009 #5


    User Avatar
    Homework Helper

    From what I've read, there are too many variables (aerodynamic drag, suspension, ...) and the math is too complex for a simple equation. From what I've read, data is collected from progressively longer jumps to create a mathematic model. I assume the model is specific to a particular motorcycle. The guys doing these jumps know the required speed for the longer jumps before attempting them. Seems like there are fewer incidents now, so maybe the mathematical models are better. You'll probably have to correspond with one of these long jumper teams to see if you can get data and/or the mathematical model, or duplicate what they do with progressively longer jumps and model the data yourself. From what I recall, most of these longer jumps are done around 90mph or so to reduce the air time (less chance for the bike to pitch into a bad attitude for landing).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook