Safe Speed Forums

I am sure it could be built, try the Kit car scene.

Dax rush 2.0 Turbo 4x4: 0 to 60 mph in 3.15 sec

I have yet to see any other road vehicle equal that acceleration, which is pulling over 2 G

0 to 100 back to 0 in 12.02 sec

Built for far less than £20,000

Have my own performance rush, would not consider putting at top speed on the road

_________________
Steve

You have obviously led a very sheltered life, come & make yourself comfortable on the back of my bike and I'll be more than happy to show you acceleration.


Never felt the need to accelerate hard and then slam the anchors on immediately afterwards, but I can do the standing quarter in 9.05 @ 152mph with a 0.34 second reaction time


Built for £2,500

_________________
What makes you think I'm drunk officer, have I got a fat bird with me?

Hyabusa 0 to 60 in 3.15, which really shows you how quick the dax really is. The dax is the fastest recorded UK road legal car!

Or was last time i looked

I really was talking about cars!

However my point was that the vehicle concerning this thread was over priced on reflection of performance.

So top end of your £2,500 machine

btw, what vehicle or bike do you have!

_________________
Steve

Nope. 0 to 60 in 3.15 seconds is an average acceleration of about 0.87g

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

That's not right is it? Sitting stationary in this chair I'm experiencing 1g. Do you mean 1.87g?

Are you accelerating? F=ma

If we lifted you and your chair up to 120 feet above ground and suddenly removed the chair, 2.7 seconds later you would hit the ground at 60mph. That's acceleration!

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

I must admit, I was wondering what sort of fancy tyres could provide enough grip for 2g+!

Even F1 cars can only attain brief peaks of about 3g, and that's with tyres that wear out in 200 miles stuck to the ground by wings that treble the effective weight of the car!

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

Depends whether we are talking relative or absolute I suppose.
In absolute terms my statement was quite correct, everyone on planet earth is experiencing 1g, it is a recognised datum. Aircraft accelerometers sit with the needle pointing to 1g when they are stationary on the ground, a 0.87g reading would mean -0.13g in relative terms.

Isn't this to do with where the force is felt? I'd have thought aircraft produce g force vertically from the point of view of any occupants, as does gravity. Surely in vehicles g is normally going to be lateral - from the front when braking, either side when cornering and from behind when accelerating - so that 0.87g isn't in addition to the normally 1g from gravity as it's coming from a different direction. I vaguely recall a piece on the F1 coverage a few years back when one or two fighter pilots got a ride in the two seat Minardi (I think) and returned the favour by taking the driver(s) up in the plane. There were comments afterwards that the pilots weren't used to g coming sideways and vice versa.

_________________
Make everything as simple as possible, but not simpler - Einstein

No no no! Gravity is a FORCE which causes unrestrained objects to ACCELERATE at 32ft per second per second. We just happen to frequently use 'g' as a unit of acceleration. In a vehicle accelerating horizontally at 1.0g the occupants experience two forces - the force of the acceleration acting horizontally throught the seat backrest and the force of gravity acting through the seat base. Both these forces are vector forces and they add to give a net force vector (remember Pythagoras) of root 2 or 1.414g acting downwards and backwards at 45 degrees.

However, we can also observe the VEHICLE accelerating horozontally at 32ft/s/s and can usefully (but potentially confusingly) term that acceleration 1.0g.

If aircraft accelerometers show 1g when static, then clearly there's a strange convention goiing on, because there is NO ACCELERATION!

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

It's quite a useful datum actually, as it allows 0g to indicate weightlessness, ie when the plane is ballistic.

When a plane is flying straight and level, 1g is correct, as that is the force being applied to the wings to support it. 0g means it is free falling, -1g means a negative force is being applied to the wings to make it accelerate downwards into a dive.

_________________
CSCP Latin for beginners...
Ticketo ergo sum : I scam therefore I am!

Understood. But on that basis, the instruments are not reading acceleration are they? They are reading force. How are these instruments labelled?

I can see how a mass suspended in the plane by six spring balances would give the result.

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

But it it only does 13 mpg - would cost a fortune to fill up as well...

We'd soon catch it It would run out of fuel before we do!

_________________
Take with a chuckle or a grain of salt
Drive without COAST and it's all your own fault!

A SMILE is a curve that sets everything straight (P Diller).

A Smiley Per post
FINES USfor our COAST!

Approach love and cooking with reckless abandon - but driving with a smile and a COAST calm mind.

You're right, acceleration is a vector quantity, it has both magnitude and direction. In the case of gravity that's 9.81 m/s2 (22.3 mph per second for us petrolheads - 0-60 in 2.8 seconds ) and the direction is straight down. But when we are stationary on the ground we aren't actually accelerating, because although there is a downwards force on us (F=ma as Paul said) there's an equal force pushing up on us from the ground (Newton's third law). The force only generates acceleration if it's unopposed.

It's normally only pilots who need to worry about acceleration in the vertical direction, so when we're talking about cars we tend to forget about it. But in a car accelerating forward, then technically, the force on the driver is the combination of the downwards force generated by gravity and the forwards force generated by the car engine. You have to get your calculator out and do trigonometry to calculate it properly.

Because in a fighter jet you turn at high speed by banking the plane and then pulling the stick back, fighter pilots experience most of their g straight down through the seat, except on takeoff. Typically 4g in a turn but it could be up to 8g, hence the need for inflatable trousers to stop the pilot blacking out due to a rush of blood from head to feet.

But F1 drivers experience all their g in the horizontal plane - about 1.5g accelerating, 2.5g braking and 4g going round corners, if I remember correctly. If they weren't strapped in so tightly they become part of the car, they'd be thrown around like rag dolls!

Have the details on the fact sheet from the speed record test, if you would like to email your fax no. i supply the fact sheet

_________________
Steve

Rush is 4x4, Rear tyres 10" wide, Front 8" wide

_________________
Steve

Fax is 01862 832002

_________________
Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

This instrument is similar to that fitted to the Harrier GR3 on which I used to work.
It is in its rest position, i.e. the aircraft is on the ground - or would be if it were fitted to one before any smart-ass comments appear
1g is the accepted standard force felt by every stationary object on planet earth.



Correct, the forces acting on an aircraft are usually said to act through the C of G - some accelerometers and 'G' meters have a remote sensor palced right on the C of G to get the most accurate reading. Nonetheless, the direction of the force is irrelevant, 1g is the datum.

I thank you...

That is based on a vehicle acceleration at the same rate throughout, which i do not believe is how a car accelerates.

Each gear will accelerate the vehicle at a differant speed, hence the G would also be differant through out acceleration.

The average is always lower than the highest G actually achieved, is it not

Thanks for your fax, i get it over Monday Morning, when i am back in the office. It makes interesting reading for a Kit Car.

_________________
Steve

0 to 100 was achieved in 7.62 sec

_________________
Steve