The slower show! (2 Viewers)

[none]

So, just for fun I figured how many HP it would take to run 400 MPH.

Used the following stats

coefficient of drag .5 which is fairly high, a muscle car
frontal area of 30 SQFT fairly large
weight 2850 race car weight

HP required
6553 HP to overcome air drag plus 40 to overcome rolling resistance for a total of

6593 HP to run 400 MPH

I don't think that your drag number is accurate, if the wing on a Top Fuel car is providing #6000+ lbs of downforce, that equates to a lot more drag does it not? (I know less than nothing about air drag.)

Also how do you factor in that you're trying to go 400 mph in four seconds? At the salt flats, I would think you could go stupid fast with 11,000 HP but you would have to figure out how to get the engine to live that long, but if were doing this in the perfect world could you go 600 mph?

One other tidbit, the speed trap used to be 66' before and 66' after, now it's 66' total. And the difference between 300 mph and 330 over that distance is 0.014 (That's why a car can pitch the belt lose 40 mph and only lose a couple of hundredths of a second ET) so I don't think that the number are very far off if you did add the last 66'

Not arguing, just asking, fun discussion!
Alan

 

[stitcherbob]

and the rest of us are like...

 

[Dragracer]

The speed clocks were 66' before and 66' after the finish line. The speed is computed by taking the time to go that 132ft and the timing system converting to MPH. The speed traps may have changed to the distance before the finish line so as you say they wouldn't run it out the back door. Don't know if what they do at 1000' for the fuel cars is the same for the 1320 classes. Anyway what is shown is not the actual speed but the average over whatever the length of the speed trap is. Not sure why they don't use a speed gun of some sort at the finish line so you can see the actual/real speed. The salt flats are just a little different, it's called NO TRACTION, real slippery. Engine life at the flats is not as big of a deal as the traction is minimal you are not running the engine at full throttle for the full run and salt flat speed is measured through the measured mile. The whole thing at the salt is how long the course is which determines how much run up length is which changes from year to year depending on the salt status. Fun discussion.

 

[ironpony]

I am not using TF, FC as an example, I am trying to figure out what is possible with the combination of the limiting factors we have in place.
7900 rpm
1:1 trans ratio
3.2 rear end
Tire radius to pavement
there is a mathematical limit, the biggest variable being tire radius, so if we could agree on a XX"s it would be fun to see the limit.

As far as the 400 mph, that was just to say 12,000 hp would be able to do it, in a 1/4 mile ? I do not know if I could figure that out.
But then again realizing 300 in the eighth mile, if we are at full rpm with perfect traction it could be close. Again we need to come up with a tire number and see what the limit is.

 

[ironpony]

I don't think that your drag number is accurate, if the wing on a Top Fuel car is providing #6000+ lbs of downforce, that equates to a lot more drag does it not? (I know less than nothing about air drag.)

Also how do you factor in that you're trying to go 400 mph in four seconds? At the salt flats, I would think you could go stupid fast with 11,000 HP but you would have to figure out how to get the engine to live that long, but if were doing this in the perfect world could you go 600 mph?

One other tidbit, the speed trap used to be 66' before and 66' after, now it's 66' total. And the difference between 300 mph and 330 over that distance is 0.014 (That's why a car can pitch the belt lose 40 mph and only lose a couple of hundredths of a second ET) so I don't think that the number are very far off if you did add the last 66'

Not arguing, just asking, fun discussion!
Alan

Alan, maybe you could inquire with some of the TF FC teams to see what the drag coefficient is, I am sure with all of their wind tunnel testing they know what that number is. They might not want to share it but ...............maybe PS too.

I change the COD to 1.0 which equal a pick up truck and the HP increased to 13,177.......

PS 600 MPH would be just over 22,000 HP

 

[Nunz]

Another difference when running on the salt, is weight. Purpose built salt flat cars are tanks, again going back to the lack of any traction. WJ referenced this when talking about his new Bonneville endeavor. Sorry if this was already mentioned.

 

[none]

Alan, maybe you could inquire with some of the TF FC teams to see what the drag coefficient is, I am sure with all of their wind tunnel testing they know what that number is. They might not want to share it but ...............maybe PS too.

I change the COD to 1.0 which equal a pick up truck and the HP increased to 13,177.......

PS 600 MPH would be just over 22,000 HP

I'm going to ask a few questions when I get to Denver
Alan

 

[ironpony]

Another difference when running on the salt, is weight. Purpose built salt flat cars are tanks, again going back to the lack of any traction. WJ referenced this when talking about his new Bonneville endeavor. Sorry if this was already mentioned.

You are correct, the weight is to create the downforce needed for traction because they do not want the drag of a wing creating downforce

 

[ironpony]

I'm going to ask a few questions when I get to Denver
Alan

Did some digging and found that a wing on a TF car creates a COD OF .6 the rear wheels/tires are .4 and the body is .017, basically a total of 1.0.
if i change the COD to 1.0 and the frontal area to 15 sqft reasonable for a TF car ?? the HP require to run 400 mph goes back down to the 6500 HP range

I can provide my "sources" if absolutely necessary.

 

[Stan]

These calculations were for something else and so the rear wheel HP is not correct. Used .5 cd and 30 sq ft. Distance is not part of this calculation.

Stan


Present_Fuel_Run
___________________________Rear______Aero____Rolling___________Rear_W__Accele___Time____Rate
__RPM______MPH___Velocity__Wheel____dynamic__Resist.__Elapsed___Horse__ration__Differ____RPM
__________________ft/sec__Torque___Drag_-_HP___HP______Time_____Power__in_G's__ential____Sec

____0.0____.000_____.000___98.92______.000____.000____.0000______0.00___0.0456__0.0000____0.0
_6844.9_280.000__410.667_8470.53__2245.729__31.920___3.1000___11039.64__4.1174__3.1000_2208.0
_8067.2_330.000__484.000_7972.60__3676.419__37.620___3.7700___12246.18__3.4019__0.6700_1824.3

---------------

Present_Fuel_Run_To_400_MPH_same_averag_G's_for the_Back_Half
___________________________Rear______Aero____Rolling___________Rear_W__Accele___Time____Rate
__RPM______MPH___Velocity__Wheel____dynamic__Resist.__Elapsed___Horse__ration__Differ____RPM
__________________ft/sec__Torque___Drag_-_HP___HP______Time_____Power__in_G's__ential____Sec

____0.0____.000_____.000___98.92______.000____.000____.0000______0.00___0.0456__0.0000____0.0
_6844.9_280.000__410.667_8470.53__2245.729__31.920___3.1000___11039.64__4.1174__3.1000_2208.0
_9778.5_400.000__586.667_9095.70__6547.315__45.600___4.7080___16934.90__3.4019__1.6080_1824.3

---------------

Present_Fuel_Run_To_400_MPH_same_averag_G's_full_run
___________________________Rear______Aero____Rolling___________Rear_W__Accele___Time____Rate
__RPM______MPH___Velocity__Wheel____dynamic__Resist.__Elapsed___Horse__ration__Differ____RPM
__________________ft/sec__Torque___Drag_-_HP___HP______Time_____Power__in_G's__ential____Sec

____0.0____.000_____.000____98.92______.000____.000____.0000______0.00___0.0456__0.0000____0.0
_6844.9_280.000__410.667__8470.53__2245.729__31.920___3.1000___11039.64__4.1174__3.1000_2208.0
_9778.5_400.000__586.667_10263.97__6547.315__45.600___4.4286___19110.06__4.1174__1.3286_2208.0

 

[Z28LT1]

So, does anyone know the tire radius on a TF car at the top end ?????

I don't think anyone has been able to get one to slow down enough to measure.

 

[Sandman]

This is really interesting, I've always wondered about downforce on TF and FC. Is it measured (wind tunnel) or calculated? I have a hard time wrapping my head around the wing on a TF car being able support my 7,000 lb F250

 

[ironpony]

This is really interesting, I've always wondered about downforce on TF and FC. Is it measured (wind tunnel) or calculated? I have a hard time wrapping my head around the wing on a TF car being able support my 7,000 lb F250

between the front wing, rear wing and wheel flaps, the little wing in front of the rear tire, generate over 10,000 lbs of down force

 

[Jeff]

It is a fun and interesting conversation.

A few years back when we were sizing the driver for our current chassis, Mike Spitzer was telling about the development of our "hump" wing (popular on TADs and TDs) I think he said at zero wing angle at 225 mph my wing would produce 800 lbs of downforce but less than 100 lbs of drag (I may be slightly off but I recall it was wind tunnel numbers with two axis of measurement). He also had the changes per degree of additional wing angle, but made one other point that really stuck with me .... the importance of the spill plates on the sides of the wing to both making efficient downforce and to keeping the car headed straight and true with other factors trying to push the car laterally and finally that they cost you essentially nothing performance wise. I understand that Mike's health is not great, but for the sportsman racers he was truly one of the sport's important and influential figures.

 

[Sandman]

Funny you should mention spill plates, I was wandering the pits at Seattle a couple years ago and noticed the wings on funny cars seemed to actually be shorter than a few years ago, but the spill plates give the illusion of a much larger wing. It made me think of an interview I read from Richard Petty commenting on the Superbirds and he said that the wing didn't give much downforce on the big tracks but if the car got sideways, the side slats would straighten the car out.

 

[Mike]

So, does anyone know the tire radius on a TF car at the top end ?????

Based on known RPM (8150) and approximate speed (320-340), and not factoring for tire slip, the math comes out to 21.1 to 22.4 inches radius (42" to 45" diameter) tire (320/340 MPH respectively)

 

[TooTall999]

Funny you should mention spill plates, I was wandering the pits at Seattle a couple years ago and noticed the wings on funny cars seemed to actually be shorter than a few years ago, but the spill plates give the illusion of a much larger wing. It made me think of an interview I read from Richard Petty commenting on the Superbirds and he said that the wing didn't give much downforce on the big tracks but if the car got sideways, the side slats would straighten the car out.

With the reduction in glue on the track, I'll bet they're a little bigger now.

 

[Huge]

And who has won the races? In the end it’s still the money guys! So your point is mute!

Bob, I'm sorry it has took me so long to respond but driving from Epping NH to South Gate Ca and reloading parts and driving to Denver CO "4,338 miles" has not given me a lot of time to hangout on my laptop. I'm not trying to change your view on the track prep because I think you are mainly interested in the quickest et, fastest mph, and records... and super prepped tracks were good for that purpose. But, I think my post has more value then you want to admit. It doesn't take a calculator to figure out that the deck is stacked against the single car teams vs the 4 car teams for an event win due to 4 times the chances and 4 times the extra data which is very, very important. But, when the tracks were super prepped the single car and smaller budget teams did not have near as much of a chance of winning rounds and even less of a chance of winning the event [with the exception of Wilkerson and Millican]. Since the track prep has been changed we have seen Scott Palmer go to a final and Blake Alexander win in TF and Shawn Reed, and Mike Salinas have made it to the finals...and Terry Mcmillen has been in a few finals this year with a win, and Clay Millican has a couple of wins this year. Here is a list of the single car teams that have had round wins already this year.
----------------------------
Clay Millican - Winner
Terry Mcmillen - Winner
Cruz Pedregon - Winner
Blake Alexander - Winner
Mike Salinas - Final
Scott Palmer -Final
Tim Wilkerson - Final
Bob Tasca - Final
Shawn Reed - Final
Greg Carillo - Semi Final
Terry Haddock
Del Worsham
Richard Townsend
Steve Chrisman
Gary Densham
Jeff Diehl
Audrey Worm
Dom Lagana
William Litton
Luigi Novelli
Kyle Wurtzel
Jonnie Lindberg
Jim Campbell
Pat Dakin

 

[ironpony]

Funny you should mention spill plates, I was wandering the pits at Seattle a couple years ago and noticed the wings on funny cars seemed to actually be shorter than a few years ago, but the spill plates give the illusion of a much larger wing. It made me think of an interview I read from Richard Petty commenting on the Superbirds and he said that the wing didn't give much downforce on the big tracks but if the car got sideways, the side slats would straighten the car out.

the drag created by spill plates defeats the gains of the added downforce, it is a delicate balance.

 

[ironpony]

With the reduction in glue on the track, I'll bet they're a little bigger now.

enlarging the spill plates would negate any downforce gains by creating drag. A wing on a TF car uses up over 2000 HP to "drag" it thru the air.