Knight Rider physics questions

[KnightInExile]

As a long-time fan of Knight Rider, I always enjoyed watching Michael and KITT turbo boost their way over obstacles, such fun! I was always curious as to how the producers managed to create those jump stunts and learned that it was done with a series of hidden jump ramps and some of the KITT cars were converted and modified for these jumps, which makes sense. However, in the show, it was established that KITT was retro-fitted with undercarriage rocket boosters, as you can see in the attached photo below:

If such a car were to be equipped with rocket boosters instead of using jump ramps, I would imagine that they would have to instantly turn off extremely quickly, otherwise, the driver could get very seriously injured or worse, killed.

Is it conceivable for a car to be installed with undercarriage rocket boosters and have them shut off within say 5 seconds after activation all without harming the driver and damaging the car? Could this be feasible?

 

[Filip Larsen]

If such a car were to be equipped with rocket boosters instead of using jump ramps, I would imagine that they would have to instantly turn off extremely quickly, otherwise, the driver could get very seriously injured or worse, killed.

Are you thinking due to high accelerations? I imagine that if the rockets on KITT are meant to give it a "boost" upwards (allowing it to fly over obstacles in an parabolic path) and not give it sustained flight for any length of time, the acceleration would be high but burn time low, a bit similar to how an jet fighter ejection seat works. Also what comes up must come down, so if KITT is to "land" again without the rockets firing once more to soften the landing, the path better not be too steep on landing, and thus it should not be too steep at the start of the jump either (assuming an otherwise flat road with an obstacle).

By the way, I only vaguely remember the series so I may be ignorant about how KITT is supposed to work.

 

[lyuc]

https://en.wikipedia.org/wiki/JATO

JATO (acronym for jet-assisted take-off), is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term JATO is used interchangeably with the (more specific) term RATO, for rocket-assisted take-off (or, in RAF parlance, RATOG, for rocket-assisted take-off gear).

 

[berkeman]

https://en.wikipedia.org/wiki/JATO

 

[DaveC426913]

https://en.wikipedia.org/wiki/JATO

JATO (acronym for jet-assisted take-off), is a type of assisted take-off for helping overloaded aircraft into the air by providing additional thrust in the form of small rockets. The term JATO is used interchangeably with the (more specific) term RATO, for rocket-assisted take-off (or, in RAF parlance, RATOG, for rocket-assisted take-off gear).

Yeah, the producers must have found an invisible form of JATO.

But seriously, JATOs are designed to provide thrust for a vehicle that requires speed to create sufficient lift.
That wouldn't apply to KITT, which would simply go faster but not lift off.
Especially if, as noted in the pic, the rockets are mounted near the rear of the vehicle.

Any rockets used would have to point downward to directly lift the vehicle over the obstruction.
And you'd want a boost at the nose, to lift it up before collision.

 

[Filip Larsen]

Any rockets used would have to point downward to directly lift the vehicle over the obstruction.

I didn't notice the backwards pointing rockets in the diagram until now, but just assumed the "designers" did the only sensible thing for jumping over an obstacle with rockets, namely to let them point downwards. Duh, forgot we are talking movies. Come to think of it, I recall seing backwards pointing rockets on cars (like in various James Bond movies) so perhaps KITT just "inherited" this bad movie design from James Bond's car maker or something similar (in which case we can blame Q, I guess).

 

[DaveC426913]

I didn't notice the backwards pointing rockets in the diagram until now, but just assumed the "designers" did the only sensible thing for jumping over an obstacle with rockets, namely to let them point downwards.

It wasn't until I went to reply that I pored over the drawing to find vertical "ports" to speak to - and instead stumbled upon the rockets aligned horizontally - causing me to change my reply completely.

 

[sysprog]

In the late '70s ('back in the day', for me) my girlfriend let me drive her Mazda RX-7, which looked a lot like KITT -- I would sometimes tease her by saying "take over Kit", then taking my hands off the wheel and stepping on the accelerator pedal -- then I would put it back into 'manual control' before it wandered severely off course . . .

 

[MikeeMiracle]

I've been in one of the KITT cars, a lot of it is just plastic buttons that don't flash or do anything. the TV's work though. Unfortunately the series has aged really badly, I tried watching it again last year and it didn't go down well.

Anyway back on topic, rockets seems like a hard way of making KITT jump. Without a ramp I would have thought some kind of pneumatic pistons at certain point in the car. Fire the piston which pushes down against the ground and forces the car upwards.

I think Indycar / Formla E use something like this for pit stops, just supply compressed air and the car lifts itself off the ground.

 

[DaveC426913]

...some kind of pneumatic pistons at certain point in the car. Fire the piston which pushes down against the ground and forces the car upwards.

That's what I was thinking too. A lot more efficient and less messy.

But it's a TV show, and rockets are cool and pistons are not.

 

[bob012345]

Would if be possible to carry and drop some sort of portable ramp just ahead of the wheels?

 

[DaveC426913]

Would if be possible to carry and drop some sort of portable ramp just ahead of the wheels?

I think that would only make sense for Inspector Gadget.

 

[lyuc]

Experimental Defense Project: Downward firing rocket on roof of vehicle to counteract the sudden lifting of the vehicle by a land mine blast. Net result: No truck getting blown into the air.

 

[MikeeMiracle]

Surely the explosion coming from underneath is the "dangerous" part, not the vehicle flying in the air...

 

[pbuk]

Surely the explosion coming from underneath is the "dangerous" part, not the vehicle flying in the air...

Watch the video.

Edit: to be fair this is not a great description:

Downward firing rocket on roof of vehicle to counteract the sudden lifting of the vehicle by a land mine blast. Net result: No truck getting blown into the air.

A better one would be:
Add a carbon fibre structure to deflect energy from a land mine blast from the floor of the vehicle into the chassis. Result: vehicle is blown even further into the air.
Solution: add a downward firing rocket on roof of vehicle. Net result: No truck getting blown into the air.

 

[Rive]

.. Downward firing rocket on roof of vehicle to counteract the sudden lifting ...

On a different angle: jumping means the vehicle is no longer steerable. I would rather expect some rockets to create downforce instead (like the wings in F1, but without the need of speed), and keep the jump-stuff for pneumatics.

Add a carbon fibre structure to deflect energy from a land mine blast from the floor of the vehicle into the chassis. Result: vehicle is blown even further into the air.
Solution: add a downward firing rocket on roof of vehicle. Net result: No truck getting blown into the air.

V-hull
MRAP

When the armour is finally sufficiently thick you no longer needs any rockets to keep it down
An IED with more than hundred kg load may still prove to be a problem.. But no rockets will save that anyway.

 

[Filip Larsen]

Surely the explosion coming from underneath is the "dangerous" part, not the vehicle flying in the air...

I had similar thoughts initially, but in the video it is mentioned that IED's often are placed by the enemy in such a way that the vehicles are likely to end up in rivers, adding drowning as a significant fatality risk.

 

[lyuc]

A better one would be:
Add a carbon fibre structure to deflect energy from a land mine blast from the floor of the vehicle ...

That part is old hat and I did not think it worth mentioning.