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Pucker Factor finally defined!

3.3K views 33 replies 17 participants last post by  thedog  
#1 ·
Well, after extensive tests and calculations, I've finally come up with the mathematical formula for "Pucker Factor," or the vacuum pressure created between ones anus and motorcycle seat during close-calls while out riding.

View attachment 34685

This gives the value in psi, which clearly indicates the amount of vacuum being applied.

Example: Mass of obstruction = 8000 pound truck
Coefficient of Friction = 0.2 between rubber wheel and wet concrete
Velocity = 70 mph
Reaction Time = 2 seconds
Gravity Constant = 32.2 ft/sec^2
Area of Sphincter = 0.5 square inch

Pucker Factor = 127,536 psi.

As you can see, it is a huge vacuum pressure.

Yes, I am an engineer with way too much time on my hands!
 
#2 ·
Just realized that non-paying members won't be able to see the equation...so here it is in text form:

Pucker Factor = {[(mass of obstruction)/(Friction Coeff.)]X[(Velocity)/(Reaction Time)]}/
[(Gravity Constant)X(Area of Sphincter)]
 
#5 ·
deadfish said:
Pucker Factor = 127,536* psi.
I think you may need to add an * for the contingency factor...otherwise known as what you had to eat for lunch that day. For example, if you had a couple of bean burritos, the psi could easily be 2 times that amount.
 
#6 ·
You may want to check the math again. And you may want to adjust the formula to show 1 divided by your pucker factor since it suggests a positive pressure as stated. The answer should be expressed in psi absolute.

Other than that it sounds about right to me. :clap:
 
#9 ·
All very good points...some assumptions were required for the analysis - measurements shown are for example only. Absolute values were used to simplify the calculations, since it can clearly be presumed that pucker is a vacuum pressure. Solid and gaseous discharge during the "pucker" were ignored due to high variability, but can definitely affect the results. Lack of volunteers makes testing the theory difficult, but I believe the trendline is quite accurate.

What a geek! :ntlgh:
 
#10 ·
8-Ball said:
Can't you just measure the deposit left on the seat?

Not really...... Corbins are hard and smooth.... the deposits tend to fly off during high speed braking..... Mustang Ultra Regals are the flip side..... the indented buttons tend to grab hold of all deposits, so it is really hard to tell if the deposit is current or something that has been accumulating......


Doug Connors

Life is not the number of breaths you take,
but finding what takes your breath away.....

----------------------------
1993 Electra Glide Sport FLHS
81" Evo w/ SE Baisley Heads
SE Forged Pistons w/ 10.5:1 CR
Woods W6H cam & Rivera PR's
SE Single Fire Adj Ign Mod & SE Coil
Mikuni HSR42 w 150 MJ, SE Air Filter
SuperTrapp TD's w/ Fishtail SO's
 
#12 ·
I believe that there are actually two different results that are possible. Depending on the meal content and the possibility of previously built-up or building gastro intestinal pressures. There is a remote chance of a 180 degree shift in the pressure values. This could easily result in not "sticking" to the seat at all, but may in fact result in something approaching that of a sub orbital launch.
In the case of some kinds of bean lunchs the equation may actually turn out to be as simple as the standard thrust = mass X velocity squared. Given many peoples reactions to various food items, the possible pressure results of same, and the HOLY CRAP factor inherent in close encounters of the large moving metal object kind.
Under these circumstances the high velocity expulsion of gasses, solids, as will as semi solids, and lastly liquids, could completely negate the pucker factor achieving positive thrust. There are far too many variables to give a predictable constant result but it could easily be enough for handlebar and maybe even short car roof clearance.
There is also the remote possibility that short pipes could influence the thrust factor by igniting some of the more flammable gasses.
 
#15 ·
Lady Godiva said:
Oh my GAWD!! LMAO! :roflback: You guys are killin' me! LOL!!
Laugh? What's so funny, this is a serious discussion of the mathematical equations needed to explain the theoretical pressure wave physics as applied to close encounters of the "HOLY CRAP!!!!" kind.


BTW Should there be a gender based "fudge" factor added in. You know, something to take into consideration the different physical shape, size, and relative softness and skin texture of the posterior region?
Wider, softer skinned butts would imply a lower inherent leakage factor, and possibly greater numeric value results, both negative & positive.
 
#16 ·
Citoriplus said:
There is a remote chance of a 180 degree shift in the pressure values. This could easily result in not "sticking" to the seat at all, but may in fact result in something approaching that of a sub orbital launch.
Speaking from personal experience and witness accounts of my unconscious, un-attentive butt being launched from a nearly-new FLHRSI in a 2004 episode, I agree (although sub-orbital launch may be a stretch). This is why I suggested that deadfish's formula makes perfect sense if it is inversely related to the data at the moment of realization. The genius of the basis for deadfish's formula is that it demonstrates that launch is possible if the effect is considered as a function over time, with the variables of velocity, area of sphincter, and reaction time all decreasing.

At the moment of realization, however, deadfish is correct - the pressure at the sphincter/seat interface is indeed close to an absolute vacuum. There are primarily two things keeping the entire seat from being forced into the body: 1) an involuntary response by the individual's nervous system which slams the sphincter (normally a one-way avenue of egress) completely shut, and 2) the presence of porous material at the interface (clothing, for example).

With respect to the involuntary response, it's probably a good thing that sheer terror and panic replace the pucker factor almost immediately or the body would implode.
 
#17 ·
thedog said:
1) an involuntary response by the individual's nervous system which slams the sphincter (normally a one-way avenue of egress) completely shut, and 2) the presence of porous material at the interface (clothing, for example).
Ya know, that reminds me of a joke:

Why are turds tapered at both ends?

Well, to keep your butth*le from slamming shut, of course! :D

Ba dum dum! Thanks - I'll be here all week - tip your bartenders and waitresses... :xhere:
 
#18 ·
Citoriplus said:
I believe that there are actually two different results that are possible. Depending on the meal content and the possibility of previously built-up or building gastro intestinal pressures. There is a remote chance of a 180 degree shift in the pressure values. This could easily result in not "sticking" to the seat at all, but may in fact result in something approaching that of a sub orbital launch.
In the case of some kinds of bean lunchs the equation may actually turn out to be as simple as the standard thrust = mass X velocity squared. Given many peoples reactions to various food items, the possible pressure results of same, and the HOLY CRAP factor inherent in close encounters of the large moving metal object kind.
Under these circumstances the high velocity expulsion of gasses, solids, as will as semi solids, and lastly liquids, could completely negate the pucker factor achieving positive thrust. There are far too many variables to give a predictable constant result but it could easily be enough for handlebar and maybe even short car roof clearance.
There is also the remote possibility that short pipes could influence the thrust factor by igniting some of the more flammable gasses.
@gree:
I WOULD AGREE COMPLETELY BUTT THERE ALSO NEEDS TO BE VALUES PLACED ON THOSE WHOM RIDE WITH IBS, IBD, CHRONES ECT...(CHRONES YOU DOOF NOT CHROME.....S) AS HAVING SHARED THE ROAD WITH A RIDER WITH THE ABOVE SHE WAS PRETTY WELL PUCKERED ALL THE TIME:whistle:
 
#21 ·
While were speaking of the pucker factor, anyone else notice it's hard to fart while riding. You actually have to lift yourself off the seat to pass an a$$ burp...or at least I do. Just one of those funny things I noticed in my early travels.
 
#23 ·
JimBurch said:
While were speaking of the pucker factor, anyone else notice it's hard to fart while riding. You actually have to lift yourself off the seat to pass an a$$ burp...or at least I do. Just one of those funny things I noticed in my early travels.
But the plus is it puts it right in line with the OL's head. =devil=
 
#24 ·
All very interesting, but in the instance of our esteemed female riding buddies, I would think the VPF or vaginal pucker factor could also play a role in saddle adhesion during panic situations. Any engineers out there want to look at the labial friction coefficient??? Okay, then, I'll volunteer. Hell, I had calculus once and I play an engineer/gynocologist on TV.... I'm over qualified!
 
#26 ·
You have ingnored the 2 stadge flow, liquid and gas. Not to mention the thermaldynamics of the flow. I did the math and came up with 43.43 in of vacuum.