post #16 of Old 10-06-2006, 08:46 AM
scottyc
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Quote:
Originally Posted by 300bhp/ton
What's RTI?
http://www.4crawler.com/4x4/CheapTricks/Ramp.shtml#RTI

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post #17 of Old 10-06-2006, 09:11 AM
JLH
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Quote:
Originally Posted by Sweeney
All you need is the height off the ground, the angle is irrelevant.
Not according to the formula I looked up.

RTI = Tire Height/sin(ramp angle*PI/180)/Wheelbase*1000


If you go here (http://www.4lo.com/calc/rticalc.htm )and plug in 18.5" for the tire height you only get a RTI of 466. That just doesn't seem right to me. In addition, you'll notice in their formula (at the bottom of the page) they are assumming a 20 degree ramp.
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post #18 of Old 10-06-2006, 09:17 AM
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Typically, you would measure the distance climbed along the length of the ramp. That number divided by the wheelbase, multiplied by 1000. This is why the score is 1000 when the rear tire hits the bottom of the ramp.

Distance / Wheelbase x 1000 = RTI

So if a TJ goes 93 inches up the ramp, 93/93x1000=1000.

That is also why a distinction is needed between a 20º and a 30º ramp when comparing scores.

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post #19 of Old 10-06-2006, 12:31 PM
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So whats the use of RTI? What does it tell us about a vehicle?

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post #20 of Old 10-06-2006, 12:34 PM
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It rates the flex of the vehicle. a way to measure the amount of flex the suspension system can take while keeping all four on the ground. Also a way to compare rigs. They do this in the "top truck challenge" to begin the competition they use the RTI and it becomes part of the score. Also I believe the angle used to be 20 but thery changed it to 30 because most ppl were scoring a perfect 1000
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post #21 of Old 10-06-2006, 12:35 PM
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Quote:
Originally Posted by 300bhp/ton
So whats the use of RTI? What does it tell us about a vehicle?
Just an artificial measurement of articulation. It's hard to compare one vehicle to another since not everyone has access to the same trails. And sometimes trails change... so when someone was looking for a standard way to measure a vehicles trail worthyness, this is what they came up with.

Obviously a score of 900 might work better on a rocky trail than a rig that scores only 400, but the lower RTI truck might climb a ledge better due to a longer wheelbase (which can lower your RTI score). So the score by no means tells the whole story.

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post #22 of Old 10-06-2006, 04:03 PM
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Sounds pretty pointless to me. Appraoch angles and ground clearance surely must be more important. I mean a leaf sprung 1950's S1 Land Rover won't flex like a modern coil sprung SUV. But I can gaurantee it'll conquer more ground with more ease.

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post #23 of Old 10-06-2006, 05:35 PM
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Quote:
Originally Posted by 300bhp/ton
Sounds pretty pointless to me. Appraoch angles and ground clearance surely must be more important. I mean a leaf sprung 1950's S1 Land Rover won't flex like a modern coil sprung SUV. But I can gaurantee it'll conquer more ground with more ease.
There is a practical (and debatable) limit to how much flex is actually beneficial, but it is doubtful that a stiff leaf-spring vehicle will run the same line as easily as a flexy coil-over buggy on many of the boulder strewn trails people are running these days.

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