Dirtbike trajectory

  • Thread starter Nickbrits
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  • #1
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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?

Thanks!
 

Answers and Replies

  • #2
rcgldr
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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.
 
  • #3
Ranger Mike
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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..


ifin you got ennuf juice,,you can make her fly!!
see 1995 Darwin Award: JATO Rocket

Named in honor of Charles Darwin, the father of evolution, the Darwin Awards commemorate those who improve our gene pool by removing themselves from it.


clown attached war surplus rocket (JATO - Jet Assist Take Off is rocket attached to C130 airplane to help it take off from short run way) to his car and achieved flight ..fir a while..see DarwinAward. com

The facts, as best as could be determined, are as follows:

The operator was driving a 1967 Chevy Impala. He ignited the JATO unit approximately 3.9 miles from the crash site. This was established by the location of a prominently scorched and melted strip of asphalt. The vehicle quickly reached a speed of between 250 and 300 mph and continued at that speed, under full power, for an additional 20-25 seconds. The soon-to-be pilot experienced G-forces usually reserved for dog-fighting F-14 jocks under full afterburners.

The Chevy remained on the straight highway for approximately 2.6 miles (15-20 seconds) before the driver applied the brakes, completely melting them, blowing the tires, and leaving thick rubber marks on the road surface. The vehicle then became airborne for an additional 1.3 miles, impacted the cliff face at a height of 125 feet, and left a blackened crater 3 feet deep in the rock.
 
  • #4
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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?
 
  • #5
rcgldr
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So I take it no one can help me on this then?
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).
 

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