Help me settle a debate

[Mw Roofline]

We are having a debate on another forum about the issue below and I wondered if you guys could put your input into this.

Here is the first post.


Posted: 09 Apr 2008 18:18

Dunno what made me think of this, but I'm sure we've all seen the bits in Nightrider and the Italian Job when a car is driven into the inside of a moving lorry or coach

It seems like a pretty foolhardy thing to do, and you do hear Michael Caine barking instructions: 'Whatever you do, as soon as we're in, hit the brakes or we'll be in the back of the cabin!'

Is what he says true, or is it *******s? i.e. say the coach is doing 60mph. Therefore the Mini will be careering towards the front of the coach at 60mph as soon as it's on the ramp - or will it

I suggested that it would be easier with a RWD car and a FWD car would be more difficult as with a RWD car once the front wheels have hit the ramp, they will just stop and its just a case of driving faster than the moving lorry until the rear wheels hit the ramp.

But then the debates have started and its turned into another 'runway' thread.

 

[Richardp]

Not many people know that !!

 

[Balenza]

Their is no difference.

In either case once the driving wheels hit the ramp they come to a stand still and you have to move the vehicle from say 4th gear (dependand on the speed you are doing) to first gear in an instant.

 

[anobium]

What would happen if the ramp had a conveyor belt on it which ran at the same speed as the coach?

Would that double the speed of the mini or would it not make any difference

 

[breezer]

you should have been watching mythbusters they did that tonight, and they reveresed a car out of a moving truck.

no problems

the narrator said (and the high speed camera showed it) the inertia of the wheel hitting the ramp causes the wheel to slow right down.

so there was no need to hit the brakes hard.


Both Jamie and Adam did it, it was easy

 

[noseall]

it is the same as walking along the roof of a moving train.

your speed PLUS the speed of the train.

once the cars drive wheels engage the (relative) motionless ramps, then the car will accelerate up those ramps.

you have to remember that the lorry is moving forwards too yet the road surface is not.

 

[EdwardCurrent]

Hello


http://www.youtube.com/watch?v=dYlstdCWzCY


Ed

 

[noseall]

and they reveresed a car out of a moving truck.

explain how this, is in any way, the same as driving onto a moving truck?

 

[noseall]

aaaah i geddit!

it's the fact that you are in a high gear and are hitting a ramp at the same speed as yourself effectively rendering your relative speed as zero.

so, it would be like trying to pull away from a dead start in top gear!

eureka.

 

[big-all]

the only important factors effecting the outcome is momentum wind reasitance friction and stored energy

the momentum and the ramp is the big problem if you enter at 20 mph faster than the van is going you need to loose 20 mph to come to rest

if you get it exactly right your momentum = the energy required to climb the ramp and you come to a stand out of gear

assuming the vehicle is doing 60mph the problem arises when the stored energy of an engine gear train and transmision are running at say 80 miles an hour to allow you to catch up
you then reduce to 70mph to climb the ramp once the drive wheels hit the ramp you have enough energy going through the transmision to overcome a 70mph head wind and all that energy will rapidly try and excelerate the car

so the secret is cluch and brake at the exact correct second or you will have enough stored energy for a front row seat

 

[breezer]

and they reveresed a car out of a moving truck.

explain how this, is in any way, the same as driving onto a moving truck?

its in reverse (as i said they did also drive it in while the truck was moving)

 

[noseall]

breezer, it is a lot easier to roll off a truck than to try and drive onto it.

you don't even need an engine.

in fact, so long as the wheels beneath you are free, then i can not see how the two compare.

 

[breezer]

i jst thought i would mention it, that was all, but as he came off he did a handbrake turn (almost) and shot off in the other direction.

I see edward current has posted a link that is waht was on tv tonight, why dont you all watch it, and watch the "high speed"

 

[blondini]

I have that feeling of deja vu... //www.diynot.com/forums/viewtopic.php?p=816516#816516 In The Italian Job stunt, the coach was doing 50mph and the cars were doing 75. I think it would be easier with a RWD car because you can get the front axle and most of the car of the car onto the ramp before having to deal with the transition of the driven wheels. Er hang on a minute lads...

 

[tim west]

did someone mention a conveyer?