Pikes Peak Race--Entering?

[itchynackers]

LFP, you are probably familiar with these... I used to run a supercharged z06. Many of the high boost pressure guys would run meth injection directly to the intake plenum. It cooled the incoming air charge, and cleaned the motor. Maybe a meth spray could work here too.

 

[MadScientist]

Dogman's VW anecdote can be explained by the fact that the higher oxygen content of dry air makes for a leaner O2/fuel ratio, which burns hotter. That problem was inside the engine, not out.

This is not the case.

Thanks for a helpful and informative response

Perhaps you can provide something more concrete? Are you disputing the fact that engines run hot when the mixture is leaned from optimal? Perhaps you believe humid air is a better conductor of heat? I'm willing to discuss this so we can find out where your misconceptions lie, but I can't help you unless you give me a little information to go on.

When I criticize someone's comment, I try to offer specific observations. For example, John in CR's assertion that humid air has "more moles" makes no sense. Air in conditions compatible with life, whether dry or humid, closely follows the ideal gas law: n = PV/RT. Note that the number of moles, n, does not depend on whether the molecules are N2, H2O, or any other small molecule.

Getting back to the subject of cooling with humid vs. dry air: I assume you are unaware that humid air has lower thermal conductivity than dry. Check out this web page from a thermal management industry publication that states the effect of humidity on cooling is "nothing to worry about".

 

[liveforphysics]

LFP, you are probably familiar with these... I used to run a supercharged z06. Many of the high boost pressure guys would run meth injection directly to the intake plenum. It cooled the incoming air charge, and cleaned the motor. Maybe a meth spray could work here too.

Right on. Supercharged ZO6 gets down and parties hard.

You're right, if you wanted to further lower the temperature you could achieve, methanol or methanol/water mix could definitely make a lower boiling point.

 

[Jethro56]

Do the axles get hot under these conditions? If so could one add heat sinks outside of the dropouts?

 

[competitions]

Seems Stealth Electric Bikes will be there.

"Stealth Electric Bikes USA will be sending riders from the U.S. & Australia to the Pikes Peak International Hill Climb in June and plans on sending riders to the Pikes Peak Challenge at the interbike conference in Las Vegas, September 14th through 16th."

 

[Green Machine]

Seems Stealth Electric Bikes will be there.

"Stealth Electric Bikes USA will be sending riders from the U.S. & Australia to the Pikes Peak International Hill Climb in June and plans on sending riders to the Pikes Peak Challenge at the interbike conference in Las Vegas, September 14th through 16th."

Thats really funny that the stealth guys fell for nimbuzz's scheme and are showing up to the gasser race in June. Knock youselves out Stealth USA!

What a dirty dog that nimbuzz to light this entire fire....and with all the confusion i bet many elecrics show up for the june race and get slaughtered by the gassers.

 

[competitions]

Seems Stealth Electric Bikes will be there.

"Stealth Electric Bikes USA will be sending riders from the U.S. & Australia to the Pikes Peak International Hill Climb in June and plans on sending riders to the Pikes Peak Challenge at the interbike conference in Las Vegas, September 14th through 16th."

Thats really funny that the stealth guys fell for nimbuzz's scheme and are showing up to the gasser race in June. Knock youselves out Stealth USA!

What a dirty dog that nimbuzz to light this entire fire....and with all the confusion i bet many elecrics show up for the june race and get slaughtered by the gassers.

nimbuzz posted the topic on ES after Stealth made the announcement... so unless he posted elsewhere, nimbuzz wasn't the impetus for Stealth to get involved.
I found the Stealth info on one of their PR announcements: http://www.prweb.com/releases/2011/4/prweb3398544.htm

Will be interesting in the days after to hear the claims from Opti and Stealth as to why they did or didn't beat each other, whether standard bikes were used etc etc.

 

[Green Machine]

So is stealth on its way to pikes in June? The pikes hill challenge?

Thats great...wish them luck for us. :wink: I think Nimbuzz is a member of the stealth forum with a different name.

 

[John in CR]

Do the axles get hot under these conditions? If so could one add heat sinks outside of the dropouts?

Yes, and some more than others. I seem to recall Dogman talking about doing just that some time ago. On the different motors I've used, the hot axle was most notable on the little geared hubs. I attribute the difference to the short thick aluminum support for the stator iron on the axle vs the much bigger distance and thin stamped steel support on my larger hubbies.

 

[John in CR]

When I criticize someone's comment, I try to offer specific observations. For example, John in CR's assertion that humid air has "more moles" makes no sense. Air in conditions compatible with life, whether dry or humid, closely follows the ideal gas law: n = PV/RT. Note that the number of moles, n, does not depend on whether the molecules are N2, H2O, or any other small molecule.

From what I read the polar nature of water molecules causes some variance away from the ideal gas law and a slightly greater molecular density of humid air vs dry, which offsets some of effect of water vapor's lower mass than air.

 

[Tiberius]

When I criticize someone's comment, I try to offer specific observations. For example, John in CR's assertion that humid air has "more moles" makes no sense. Air in conditions compatible with life, whether dry or humid, closely follows the ideal gas law: n = PV/RT. Note that the number of moles, n, does not depend on whether the molecules are N2, H2O, or any other small molecule.

From what I read the polar nature of water molecules causes some variance away from the ideal gas law and a slightly greater molecular density of humid air vs dry, which offsets some of effect of water vapor's lower mass than air.

Humid air is less dense than dry air. It's one of the factors to take into account when calculating density altitude (see earlier in the thread). The important thing is that the molecular weight of H20 is less than that or O2 or N2.

The polar nature of H2O is why it's a liquid at normal temperatures, when a non polar molecule of that weight would be a gas.

Sorry, don't really want to spoil a good thread by lobbing a fact into it.

Nick

 

[Green Machine]

MIght as well join in Nick...

This thread is thick with facts....mixed in with foolery and threats on life and limb.

 

[dogman dan]

It would definitely be a good idea to run one of those personal misters on the hub. Apply evaporative cooling, or if really humid that day, just transfer heat to the water that slings away. But that will cool the cover, which doesn't run the motor at all. cooling the windings is stll the problem. Maybe mist the thing through a cover with holes?

Cool to hear folks are showing up. Both for the race to the clouds and the bike ride. I pretty much blew my annual fun budget on the DR, but who knows what I'll do at the last moment. I'd love to see what a dual hub 2810 bike could do. Or just see if a stock 9c kit could hack it. Beating the opti on a stock 2807 running 48v wouldn't suprise me any. Just a matter of riding to 200F and holding it there. If you have to carry water to mist the hub with fine.

 

[Jethro56]

One of the problems I've read about trying to cool these hubs is that drilling holes doesn't induce airflow thru them. One idea was to setup a endothremic reaction inside the hub. I don't remember the equations from 35 years ago to know if this is practical or if there is an advantage to this over spraying water on the hub. Just an alternative approach.

 

[Tiberius]

MIght as well join in Nick...

This thread is thick with facts....mixed in with foolery and threats on life and limb.

If it weren't so far away, I would join in properly.
I do have form at hill climbing.

 

[Green Machine]

NIck...now that is righteous hill climb trophy...good man. Is that a trophy???

 

[Toorbough ULL-Zeveigh]

If the game is to win it with a direct drive hub (and it sounds like the opti-guys realize that if we do RC drive it's a no-brainer outcome)

optibike's shittin' lipo bricks & have already conceded.
unless someone's heard different, their Pikes Peak $5000 opti challenge that's been gradually watered down thru the years is now gone completely.

http://tech.groups.yahoo.com/group/power-assist/message/60645
http://groups.google.com/group/optibike-owners-group/browse_thread/thread/1df4e3398c5c9329/bcb2773f7a87f2fa

Dogman's VW anecdote can be explained by the fact that the higher oxygen content of dry air makes for a leaner O2/fuel ratio, which burns hotter. That problem was inside the engine, not out.

This is not the case.

Thanks for a helpful and informative response

Perhaps you can provide something more concrete? Are you disputing the fact that engines run hot when the mixture is leaned from optimal? Perhaps you believe humid air is a better conductor of heat? I'm willing to discuss this so we can find out where your misconceptions lie, but I can't help you unless you give me a little information to go on.

When I criticize someone's comment, I try to offer specific observations. For example, John in CR's assertion that humid air has "more moles" makes no sense. Air in conditions compatible with life, whether dry or humid, closely follows the ideal gas law: n = PV/RT. Note that the number of moles, n, does not depend on whether the molecules are N2, H2O, or any other small molecule.

what would be the point of providing something more concrete to a closed mind?
after all:

You will not win by arguing technical points with me.

btw, it is you that owes everyone an apology, for trying to dictate who has the right to come out and play as some self-appointed arbiter of what constitutes 'bad taste'.
(and you can't out what was never in, 2face. )

 

[gtadmin]

...Sorry, don't really want to spoil a good thread by lobbing a fact into it.

Nick

 

[John in CR]

When I criticize someone's comment, I try to offer specific observations. For example, John in CR's assertion that humid air has "more moles" makes no sense. Air in conditions compatible with life, whether dry or humid, closely follows the ideal gas law: n = PV/RT. Note that the number of moles, n, does not depend on whether the molecules are N2, H2O, or any other small molecule.

From what I read the polar nature of water molecules causes some variance away from the ideal gas law and a slightly greater molecular density of humid air vs dry, which offsets some of effect of water vapor's lower mass than air.

Humid air is less dense than dry air. It's one of the factors to take into account when calculating density altitude (see earlier in the thread). The important thing is that the molecular weight of H20 is less than that or O2 or N2.

The polar nature of H2O is why it's a liquid at normal temperatures, when a non polar molecule of that weight would be a gas.

Sorry, don't really want to spoil a good thread by lobbing a fact into it.

Nick

Nick,
Don't stop there. There seemed to be agreement that humid air is lighter than dry air. The part that's missing is why the heavier dry air isn't as much better for heat transfer as the ideal gas law would indicate. Got any facts that help? The polar thing causing some departure from the ideal gas law was all I could find.

 

[John in CR]

One of the problems I've read about trying to cool these hubs is that drilling holes doesn't induce airflow thru them. One idea was to setup a endothremic reaction inside the hub. I don't remember the equations from 35 years ago to know if this is practical or if there is an advantage to this over spraying water on the hub. Just an alternative approach.

Ventilating the hub does in fact work, but it has to be much more strategic than is commonly done around here in order to turn the motor shell into a centrifugal fan to stimulate useful flow and get the flow where you want it, across the windings and through the air gap. I wouldn't even consider this climb without the motor ventilated, and I'd take the extra precaution of going active with blowers in the the brake drum cover. I've only been up to a mile high with my bike, and pedal assist would be out of the question for me at 14kft. My motor is already pushing twice the load, so I'd want to give it as much thermal assist as possible.

 

[Alan B]

Make sure your blowers don't overheat themselves or blow bearings at 14,000 feet (underloaded and overspeeding) and are still actually effective at moving air. They also add their own heat which now must be handled as well. Plus additional power consumption.

 

[MadScientist]

btw, it is you that owes everyone an apology, for trying to dictate who has the right to come out and play as some self-appointed arbiter of what constitutes 'bad taste'.

Are you suggesting that showing up to this USA Cycling sanctioned Fun Ride with the 6000W motorcycle-with-pedals mr greenwhatever was foaming at the mouth about is in good taste?

You seem to have trouble understanding that this is a bicycle ride, and that motor vehicles are specifically prohibited.

 

[Jethro56]

One of the problems I've read about trying to cool these hubs is that drilling holes doesn't induce airflow thru them. One idea was to setup a endothremic reaction inside the hub. I don't remember the equations from 35 years ago to know if this is practical or if there is an advantage to this over spraying water on the hub. Just an alternative approach.

Ventilating the hub does in fact work, but it has to be much more strategic than is commonly done around here in order to turn the motor shell into a centrifugal fan to stimulate useful flow and get the flow where you want it, across the windings and through the air gap. I wouldn't even consider this climb without the motor ventilated, and I'd take the extra precaution of going active with blowers in the the brake drum cover. I've only been up to a mile high with my bike, and pedal assist would be out of the question for me at 14kft. My motor is already pushing twice the load, so I'd want to give it as much thermal assist as possible.

Without constraining thinking into just this approach where I was going was along the lines of taking something like R134 (actually my first though was NH3 but it's too dangerous) and releasing it into the hollow axle. Then having holes on the other side of the coils for it to flow thru the motor. Probably impractical but it may expand the thinking into unconsidered alteratives.

 

[liveforphysics]

R134 absorbs an insignificant amount of energy compared to a dribble of water.

AC systems are needed if you need to drop below ambient. Since water boils at a lower temp than the motor takes damage, and water is safe to use as a total-loss cooling system, its all you need.

 

[bigmoose]

I am so glad that you guys are starting to talk about "total loss water cooling systems." I think it is the answer for drag, and hill climbing cooling. Distilled or de-ionized water, perhaps with some corrosion inhibitor additive from boiler make up chemistry, and a surfactant (remember the drop of dawn dishsoap that I mentioned... one drop Vasili, one drop only!). Followed by a good spray with a water displacer like WD40 after the run. In a cycling road race, don't they hand water out to the riders? Some of that needs to then be dumped into the bikes cooling system. I like hollow frames for storing the coolant.

Lets throw some number out there:
Liquid Nitrogen 200 KJoules/Kg
R134a car freon 215 KJoules/Kg Note there is no real benefit to liquid nitrogen over R134a in the Heat of Vaporization race.

Ethyl Alcohol 855 KJoules/Kg Sure a lot better than the two above

Plain old Water 2260 KJoules/Kg ... makes me take notice!

1 lowly quart of water, or 1 Kilogram will absorb 2260 KJoules to vaporize!

Lets add to it the specific heat needed to raise the water from say 20 degC to 99 degC. Specific Heat of water, if I did the units right is 4.186 KJoules/Kg/degC Not too shabby either! So for 1 liter of water we add 331 KJoules

Our total ability for that one quart of water is 2260 + 331 = 2591 KJoules. Now for us who do not think in metric... oh the travesty... 1 Joule = 1 watt for one second. So that quart of water will take away 2,591,000 watt-seconds of energy.

Lets take that 20 minute ride to the top of the mountain. 20 X 60 = 1200 seconds
2,591,000 Watt-seconds can be harvested to turn our precious water to steam. If I want to do it all in that 1200 second ride to the top; I can magically absorb 2,159 watts each and every second in my quest for victory!! That's two kilo watts folks! At 80 % efficient motor; I can cool a motor that is running 10 KW input!

Now to hit submit, and then be in 10 minutes when I learn of all the conversion errors I made from power to energy and back again...

PS: We know that none of this will be 100% efficient, some of the mist will be lost as water and not steam... so make it 50% and 5 KW input... that should do nicely!