Weighting & Aerodynamics

[gWebber]

Ok, new crazy idea (or is it?)

Now I know a 1/4 thick body doesn't suffer a huge amount by having a "VACUME" accure at its squared off tail. But I had this thought of making a more aerodynamic car tail using tungsten putty for a smoother air flow.
I mean it can't hurt right?

This might mean possibly shortening the nose by an equal amount to stay at 7" depending on the exact configuration.

I guess the big question with this is, how much weight behind the axle is too much?

Would 12 cubes and a tungsten tail be too much? (Hard to tune maybe) or would 6 cubes and roughly the equal weight of 6 more cubes in putty be better?

Opinions?

 

[Momentum Racing]

I wouldn't go with more than 2 oz total behind the rear axle,and that's assuming your rear axle is 5/8" from the back of the car.

I vaguely remember reading one of Randy's articles over at MV that did a test on rounding the rear of the car as you mentioned, I'm pretty certain there was a very small improvement in doing so.

 

[GravityX]

Too much weight behind the real axle is too much when you have no weight on the DFW to keep the nose of the car down. Of what you are talking, adding a little bit of tungsten putty should not add too much weight back there, COM/COG or whatever, gets more aggressive and loosens the car up. There is a point of diminishing returns.

Keep in mind, whatever length you add to the back of the car you'll have to remove it from the front of the car, in order to maintain the proper car length of 7 inches.

 

[Kinser Racing]

I've already done the tail but I did it without putty and without to much weight behind the rear axle. Needless to say the car never won. It did come within .0001 of winning once. It wasn't as fast as its successor.

 

[bracketracer]

I vaguely remember reading one of Randy's articles over at MV that did a test on rounding the rear of the car as you mentioned, I'm pretty certain there was a very small improvement in doing so.

I remember that test, but he used a shop air blower that might have had more airflow than these cars normally see? Testing at too high of a mph might produce invalid results?

 

[Momentum Racing]

I remember that test, but he used a shop air blower that might have had more airflow than these cars normally see? Testing at too high of a mph might produce invalid results?

That's a good point Br, I don't remember the particulars of the test, it just rang a bell when gweb mentioning rounding the rear.

 

[gWebber]

That's a good point Br, I don't remember the particulars of the test, it just rang a bell when gweb mentioning rounding the rear.

I've seen two things on the subject, one used a shop blower as you said, the other (I forget where I saw it) they had adjusted the air speed roughly match the cars actual max speed on the track.

Of course these test both seem to be looking at "drag" and not so much on turbulence that might cause drag or instability.

 

[Cramjet]

I have proposed this idea before. Find a track and set it up in a place where you can invite smokers/stoners and has little ventilation. The smoke in the room will be thick enough to see every variation in air movement.

 

[Momentum Racing]

I have proposed this idea before. Find a track and set it up in a place where you can invite smokers/stoners and has little ventilation. The smoke in the room will be thick enough to see every variation in air movement.

I may know of just such a place./images/boards/smilies/biggrin.gif

 

[bracketracer]

There was at least one car entered in Street Stock in Omaha that was tapered in the rear and even had trailing fenders at the rear. Iceman's STP entry. Looked really well made.

 

[Momentum Racing]

There was at least one car entered in Street Stock in Omaha that was tapered in the rear and even had trailing fenders at the rear. Iceman's STP entry. Looked really well made.

So it was not running the popular 5/8" rear axle location?

 

[DURASPANK]

I have proposed this idea before. Find a track and set it up in a place where you can invite smokers/stoners and has little ventilation. The smoke in the room will be thick enough to see every variation in air movement.

Find a vape shop that'll set up a track. Those places are a total cloud.

 

[bracketracer]

So it was not running the popular 5/8" rear axle location?

No, it did not appear to be a 5/8" drill.

 

[Momentum Racing]

No, it did not appear to be a 5/8" drill.

I noticed the winning BASX car in last months league race also didn't have a 5/8" drill, it looks like a standard 4-3/8" wheelbase in the standard position.

Just when you think there is some general consensus as to what works in this sport ,you see things like this and start to reevaluate everything./images/boards/smilies/crazy.gif

 

[bracketracer]

I noticed the winning BASX car in last months league race also didn't have a 5/8" drill, it looks like a standard 4-3/8" wheelbase in the standard position.

Just when you think there is some general consensus as to what works in this sport you see things like this and start to reevaluate everything./images/boards/smilies/crazy.gif

Sometimes a "bigger motor" isn't the fastest option......

 

[Kinser Racing]

I noticed the winning BASX car in last months league race also didn't have a 5/8" drill, it looks like a standard 4-3/8" wheelbase in the standard position.

Just when you think there is some general consensus as to what works in this sport you see things like this and start to reevaluate everything./images/boards/smilies/crazy.gif

If you go to the David Copperfield show in Vegas, he makes a car appear out of nowhere.

 

[Momentum Racing]

Sometimes a "bigger motor" isn't the fastest option......

You know it brother ! /images/boards/smilies/tongue.gif......so if he didn't start with the biggest motor, there is only one way he could win...he used less energy.....now, how he went about that is the million dollar question./images/boards/smilies/confused.gif

Hold on, hold the presses ....moving the rear axle forward would allow room for an even bigger motor than the 5/8" location. If he could keep that big block Hemi tamed down he could have incredible times. That's how he did it ,that sneaky son of a -----./images/boards/smilies/sneaky.gif/images/boards/smilies/biggrin.gif

 

[Momentum Racing]

If you go to the David Copperfield show in Vegas, he makes a car appear out of nowhere.

How much steer does it have ?... and how is it weighted?...I might be interested.