Paul, if it's not too much trouble, could you provide the wheelbase, static wheel loads, and average 60 foot time. Oh, and a rough "eyeball" estimate of the CG height, too.
Looks like the acceleration is, in fact, fairly constant for the first 60 feet.
wind speed effect on dragster
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BillyShope
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The 60 foot time can very depending on what track , weather and HP adder. That trend has the 60 foot for that pass.
I have know way to give the detail you want above. No weight scales
It is 236" Wheel base 4 link dragster
I did map the instant center when I made a move a few moths ago.
I have know way to give the detail you want above. No weight scales
It is 236" Wheel base 4 link dragster
I did map the instant center when I made a move a few moths ago.
Paul
Adv Et Dragracer
Adv Et Dragracer
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BillyShope
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Thanks, Paul. I hadn't noticed the ET's at the top. Wanted the wheel weights so that I could compare your transducer results with my spreadsheets. As you've probably noticed, most of my spreadsheets requre the use of wheel scales. No, I'm not sponsored by Longacre, but probably should be.
Did you catch that Muscle Cars episode on the Ramchargers last night? That's the first time much coverage has been given to the first car (the High&Mighty C/A). Thornton was incorrect, though, when he said that we set the speed record and retained it for three years. We set the best speed FOR THE MEET (the Nationals), but the actual record was held by Billy Rassmussen of Texas with his Dodge hemi powered coupe. (He beat us in the eliminations.) Later, we set and reset both national speed and ET records with the car.
Did you catch that Muscle Cars episode on the Ramchargers last night? That's the first time much coverage has been given to the first car (the High&Mighty C/A). Thornton was incorrect, though, when he said that we set the speed record and retained it for three years. We set the best speed FOR THE MEET (the Nationals), but the actual record was held by Billy Rassmussen of Texas with his Dodge hemi powered coupe. (He beat us in the eliminations.) Later, we set and reset both national speed and ET records with the car.
Billy I'm embarrassed to say that I only watch the AM news as I choke down some bread and coffee and only for Traffic info, Weather and muggings in my area. 
So I missed that show. In fact I have never seen it. I travel now and than for work and when stuck in the Hotel look at the Discover Channel and like the Myth Busters show.
When not doing honey do's, ebay sales or messing with my race car, I spend way too much time on the Internet and mostly web sites like this.
I've been doing this sense the old Prodigy days. I think it's fun to interact with folks from all over the place and I tend to learn a great deal more than from local racers. For some reason few local racers want to share anything at all.
As an engineer in maybe the last 10 years of my career, I have found it satisfying to turn out. That also applies to racing. I consider myself to be a novice, but find I can help many racers with advice and I just feel good about that.
So I missed that show. In fact I have never seen it. I travel now and than for work and when stuck in the Hotel look at the Discover Channel and like the Myth Busters show.When not doing honey do's, ebay sales or messing with my race car, I spend way too much time on the Internet and mostly web sites like this.
I've been doing this sense the old Prodigy days. I think it's fun to interact with folks from all over the place and I tend to learn a great deal more than from local racers. For some reason few local racers want to share anything at all.
As an engineer in maybe the last 10 years of my career, I have found it satisfying to turn out. That also applies to racing. I consider myself to be a novice, but find I can help many racers with advice and I just feel good about that.
Paul
Adv Et Dragracer
Adv Et Dragracer
BillyShope:
I finally found some numbers that might help with your estimation of the drag on a AA fueler style dragster.
In HP books "Aerodynamics" pg 56 they mention that Jim Head and his engineer Chuck Hallum delayed chute opening and brake application on a run to gather data. The result was that the inherent aero drag of the body and rolling drag of the tires provided 5000# of force at 300 mph, they show a plot of inherent drag with about 2.4 G deceleration without brakes or chute deployed.
He also mentions that an exposed tire and wheel of the proportions seen in F1 or Champ cars typically has a Cd of 0.56 -0.60.
He quotes a typical Cd for a common dragster configuration at 0.65 on page 19
There are several empherical formulas for rolling resistance of wheels with respect to weight and speed but I am not sure any of them are good approximations of the drag slick.
I also realized that the aerodynamic frontal area of the slick changes during the run due to tire growth, so static frontal area and terminal speed frontal area would be different which would be an interesting accomodation to make in a workable drag formula.
Larry
I finally found some numbers that might help with your estimation of the drag on a AA fueler style dragster.
In HP books "Aerodynamics" pg 56 they mention that Jim Head and his engineer Chuck Hallum delayed chute opening and brake application on a run to gather data. The result was that the inherent aero drag of the body and rolling drag of the tires provided 5000# of force at 300 mph, they show a plot of inherent drag with about 2.4 G deceleration without brakes or chute deployed.
He also mentions that an exposed tire and wheel of the proportions seen in F1 or Champ cars typically has a Cd of 0.56 -0.60.
He quotes a typical Cd for a common dragster configuration at 0.65 on page 19
There are several empherical formulas for rolling resistance of wheels with respect to weight and speed but I am not sure any of them are good approximations of the drag slick.
I also realized that the aerodynamic frontal area of the slick changes during the run due to tire growth, so static frontal area and terminal speed frontal area would be different which would be an interesting accomodation to make in a workable drag formula.
Larry
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BillyShope
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Thanks, Larry! For practical purposes, we don't really need to know the drag coefficient or frontal area when we have empirical data like that which you provide. This can be reduced to:
Force Required = 0.0555 Speed^2
with Speed in mph.
The equivalent constant for a '60 Valiant is 0.025, so we can see that the dragster is about as aerodynamic as a brick. Well, not quite as good as a brick. (It should be recognized, of course, that a very large part of the dragster's aero drag is a result of the wing. A wing doesn't only provide downforce; it also provides almost as much aero drag.)
Thanks, again.
Edit: Just out of curiosity, I went back to my quarter mile program, changed the internal code to correspond to Larry's information, and set up a 300 mph dragster. I then went back and returned the code to its "normal" value. The speed jumped from 300 to 392 mph! Of course, we won't see these numbers until NHRA allows a skirted dragster with an auxilliary engine to suck out the air under the car, ala the Chaparral "Sucker Car" of the 70's. Don't hold your breath! I'm not sure anybody (except, maybe, some sponsor) would want the dragsters going that fast.
Force Required = 0.0555 Speed^2
with Speed in mph.
The equivalent constant for a '60 Valiant is 0.025, so we can see that the dragster is about as aerodynamic as a brick. Well, not quite as good as a brick. (It should be recognized, of course, that a very large part of the dragster's aero drag is a result of the wing. A wing doesn't only provide downforce; it also provides almost as much aero drag.)
Thanks, again.
Edit: Just out of curiosity, I went back to my quarter mile program, changed the internal code to correspond to Larry's information, and set up a 300 mph dragster. I then went back and returned the code to its "normal" value. The speed jumped from 300 to 392 mph! Of course, we won't see these numbers until NHRA allows a skirted dragster with an auxilliary engine to suck out the air under the car, ala the Chaparral "Sucker Car" of the 70's. Don't hold your breath! I'm not sure anybody (except, maybe, some sponsor) would want the dragsters going that fast.
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BillyShope
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NUTS!!! I keep forgetting that I use feet/second in my spreadsheet calculations and not miles per hour. I thought that 392 figure was just a wee bit too much. Make that about 331 mph with a streamlined sucker car. That's close enough to the present numbers to hopefully discourage anyone from building such a thing. Not that the NHRA would change its rules, anyway.
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