Where does a Top Fuel dragster accelerate the hardest?

[.]

http://dragnews.com.au/news-all/loc...top-fuel-dragster-accelerate-the-hardest.html

 

[Cliff]

So it looks like his highest G force is at the 330' mark. Was looking at 1/8 mile times, 3.01 at "only" 283, but he ran 322 MPH 1000'. So now I'm wondering how a 3.6 ET at 1000' would look like on the graph. I think Leah ran like 2.92 1/8 mile at 296 MPH, so I wonder where her peak G's came in? This is really interesting to see the graph. Man I'm glad I'm not a crew chief!!!

 

[none]

Where did Tommy Johnson's axle shear off? At the highest stress point on the track.
Come to Nitro School and we talk about this. Here's one of my graphs, from a Top Fuel run.

Alan

 

[mgty3whlr]

So almost 5.5 G's at the top end because the clutch is 1 to 1 by then? I'm guessing... And the graph I'm thinking are 1 second blocks?

 

[TooTall999]

The hardest acceleration is the initial 0-4 G. After that it climbs to that 5.5 G mark, but not nearly as hard.

 

[none]

The hardest acceleration is the initial 0-4 G. After that it climbs to that 5.5 G mark, but not nearly as hard.

So you think 4 G's is accelerating harder than 5.5 G's? The hardest acceleration is the highest G number. The driver is getting shoved back into the seat harder at 300' than the first move. We talk about that every week at Nitro School.

Alan

 

[Cliff]

Alan, buddy, pal.... Do you have any videos, like on U Tube, that show what you talk about at Nitro School? Would really love to see that, would really be interesting.

 

[ironpony]

0-4 is like getting rear ended by a train, 4-5.5 is like being squeezed back into the seat, yes 5.5 is more overall force on the body but 0-4 is more stressful.

 

[TooTall999]

So you think 4 G's is accelerating harder than 5.5 G's? The hardest acceleration is the highest G number. The driver is getting shoved back into the seat harder at 300' than the first move. We talk about that every week at Nitro School.

Alan

Alan, the intitial 0-4G acceleration happens much quicker than the 4-5.5G. Yes 5.5G is more force, but the inititial acceleration is much harder.If you look at the graph, the 0-4G line is nearly vertical, which is almost instantaneous. The climb from 4-5.5G is more gradual and steady. The question was where is the acceleration the hardest, not where does the driver see the most G forces.

 

[Randy]

We asked a big name TF racer that question a few years ago. He said when racing on nitro nothing accelerates harder or faster than your credit card balances.

 

[none]

Alan, the intitial 0-4G acceleration happens much quicker than the 4-5.5G. Yes 5.5G is more force, but the inititial acceleration is much harder.If you look at the graph, the 0-4G line is nearly vertical, which is almost instantaneous. The climb from 4-5.5G is more gradual and steady. The question was where is the acceleration the hardest, not where does the driver see the most G forces.

David,
The initial hit is just that, a hit. If you get rear ended by a dump truck, you will get a lot of G's but not a
lot of acceleration. But it is accelerating MUCH harder in the middle. They move harder from 150 mph to 300 mph, than they do from 0 to 150.

Here's the engine (red) and driveshaft (green) when it gets that initial hit it is only going from zero to about 40 mph. I guess you could argue that the slope isn't as vertical after that, but it really is accelerating harder. because some of that first driveshaft spike is tire slippage. After the RPM dips, and the tire gets planted it starts moving.

Alan
BTW, great discussion.....

 

[TooTall999]

Well Alan, as neither of us is going to climb into a top fueler and try it out, we'll just have to agree to disagree...lol

 

[8sec71]

Well Alan, as neither of us is going to climb into a top fueler and try it out, we'll just have to agree to disagree...lol

5.5 g's is much harder acceleration than 4 g's. It's that simple. Just because you started at zero and went right to 4 is irrelevant, 5.5 is still more.

Weird analogy, Imagine you're laying on the ground and someone sets 400lbs of weight on you, then a second later they add another 150lbs for a total of 550lbs. When do you have the most weight, the initial 400 or the total of 550 a second later? So at the hit in the fuel car you get 400lbs of pressure on your back side that increases to 550lbs a second later as it starts to accelerate even harder.

 

[TooTall999]

5.5 g's is much harder acceleration than 4 g's. It's that simple. Just because you started at zero and went right to 4 is irrelevant, 5.5 is still more.

Weird analogy, Imagine you're laying on the ground and someone sets 400lbs of weight on you, then a second later they add another 150lbs for a total of 550lbs. When do you have the most weight, the initial 400 or the total of 550 a second later? So at the hit in the fuel car you get 400lbs of pressure on your back side that increases to 550lbs a second later as it starts to accelerate even harder.

I never said 4G's was more than 5G's. The original question was:
"Where does a Top Fuel dragster accelerate the hardest?"
The acceleration from a standing start to 4G's is harder than the acceleration from 4G's to 5.5G's. Look at the graph. It's like having that 400lb weight dropped on you, then another 150lb weight added slowly.

 

[T.Smith]

View attachment 4117 Where did Tommy Johnson's axle shear off? At the highest stress point on the track.


Alan

...and the end off of our reverser at RT66.

 

[Randy]

You can see in the graph where the engine RPM (red) and driveshaft RPM (green) meet (it's locking up the clutch) the tires are trying to let go as evidenced by the richter scale looking squiggly lines in green for a short period of time. Also, it always amazes me that, at clutch lock where the two lines come together, the rate of acceleration diminishes after lock up rather than getting stronger as evidenced by nosediving driveshaft speed rate of acceleration. Lay a ruler or straight piece of paper diagonal across your screen on Alan's full screen graph above along the driveshaft speed (green) line and notice where it starts to dive. You would think that when the clutch stops slipping and the engine goes one to one with the driveshaft it would really take off. Not so. And this is the same thing we see in TA/FC and TAD. Clutch locks up, car quits accelerating at the same point. Fun to see these graphs again.

 

[.]

The hardest acceleration is the initial 0-4 G. After that it climbs to that 5.5 G mark, but not nearly as hard.

The rate of change is the highest at the hit, but that doesn't mean it's accelerating the hardest there.

 

[TooTall999]

I still maintain the initial acceleration is the hardest, but it is shorter in duration than the climb from 4g-5.5g.

 

[.]

I still maintain the initial acceleration is the hardest, but it is shorter in duration than the climb from 4g-5.5g.

G force numbers don't lie. The harder the acceleration the higher the G force.

 

[ironpony]

G-force is the measurement of acceleration that causes a perception of weight

Acceleration is the RATE of change in velocity

based on the graph provided the rate of CHANGE is the greatest on the initial hit 0-4g's in milliseconds