Limitless LibertyMkiii's crazy belt drive car project

[limitless202+]

I agree with your assessment here. I will, however, offer up one factor that Raz mentioned in passing that you left out (not intentionally I don't think; may have just passed it over as he did just mention it briefly but I do think it's the most relevant, as the other two, I would agree, aren't really factors beyond perhaps 1-2mph).

The elevation. Or rather, the lack thereof. I don't know what elevation Raz's airfield is at, but from the videos it did look like the airfield where ROSSA is hosted is very close to sea level, which might not make a huge difference in normal situations, but when you begin to approach 200mph, it's more like "driving a car through a cheese cake" to, once again, quote Jeremy Clarkson. To that end, I do think that driving at higher elevations would provide a significant advantage in speed running as the motors, obviously, don't require oxygen to function.

Anyone got a runway in Denver? If so, get crackin'!!

Lol yep!! I’m in Longmont, 5,000 feet above sea level, so does that give me an advantage??

i mean 4800 feet…

 

[Velodromed]

Yeah, it does. I'll still consider Michael Phelps a swimmer after his swimming career is over and, at least from what I've gathered here and there, it sounds like you were pretty serious into cycling at some point. And your name is Velodromed so...to me, you're still a cyclist

Thanks man! Gave me a feel good moment as I wake up here to get the kid ready for school I am gonna be able to get back on my bike a couple months after my surgery... but my wife’s made it clear that I can only ride my bike with the kid (this whole conversation happened in front of the surgical doctor). No going off on my own because we both know what will happen if I do (my nickname wasn’t Crash for no reason). She doesn’t put her foot down often with me, actually hardly ever, but in this case she is fully justified and I will try to listen

Mostly get hot when braking

This is a concept that I only heard about this last month or so. Over two years of running these little cars and never occurred to me how breaking affects the system.

Yesterday I got out to the park with the kid and ran my parts bin typhon for a couple of packs. The first pack I drove like I normally do, fast and braking a lot. The motor heated up pretty quick to 150-160f. I let it cool down and ran a second pack, mostly full throttle but hardly braking at all, and the motor never went over 130f. That opened my eyes to a big part of my motor heat issues. I brake too much

 

[jondilly1974]

Thanks man! Gave me a feel good moment as I wake up here to get the kid ready for school I am gonna be able to get back on my bike a couple months after my surgery... but my wife’s made it clear that I can only ride my bike with the kid (this whole conversation happened in front of the surgical doctor). No going off on my own because we both know what will happen if I do (my nickname wasn’t Crash for no reason). She doesn’t put her foot down often with me, actually hardly ever, but in this case she is fully justified and I will try to listen

This is a concept that I only heard about this last month or so. Over two years of running these little cars and never occurred to me how breaking affects the system.

Yesterday I got out to the park with the kid and ran my parts bin typhon for a couple of packs. The first pack I drove like I normally do, fast and braking a lot. The motor heated up pretty quick to 150-160f. I let it cool down and ran a second pack, mostly full throttle but hardly braking at all, and the motor never went over 130f. That opened my eyes to a big part of my motor heat issues. I brake too much

Yep just peg the throttle and never let go!

 

[Diem Turner]

Why Denver? It’s not really that high of elevation. Try Colorado Springs at probably 2000ft higher elevation and the Air Force Academy runways

Hell let’s do a Pikes Peak descent speed run

Mostly get hot when braking

I figured "Mile High" was a good place and I didn't really put a whole lot of thought into it at the time but, I can do better.

Anyone got a runway in Daocheng? If so, get crackin!!

 

[Pat_ranch]

Ok, now we've wandered into my wheelhouse as a precision shooter. Elevation is only part of the equation. The term you'll need to get acquainted with is density altitude. The DA is the measure of how "thick" the air is. Higher DA gives less resistance. Heat, humidity, and elevation all go into DA. Find yourself a hot, dry, and high strip, and you'll notice significantly less drag. On a hot dry day around here (el 5200-ish) we'll see the DA climb up into the 8000+ft range. During a blizzard, it'll plummet to 1500ft. I've never really thought about it for rc, but I've also never gotten over 100mph. I suspect once you push closer to the 200mph mark, you actually need to think in ballistic terms...

 

[Velodromed]

Ok, now we've wandered into my wheelhouse as a precision shooter. Elevation is only part of the equation. The term you'll need to get acquainted with is density altitude. The DA is the measure of how "thick" the air is. Higher DA gives less resistance. Heat, humidity, and elevation all go into DA. Find yourself a hot, dry, and high strip, and you'll notice significantly less drag. On a hot dry day around here (el 5200-ish) we'll see the DA climb up into the 8000+ft range. During a blizzard, it'll plummet to 1500ft. I've never really thought about it for rc, but I've also never gotten over 100mph. I suspect once you push closer to the 200mph mark, you actually need to think in ballistic terms...

Thank you very much sir! You made me a little bit smarter on the things I’ll probably never use but still love.

 

[LibertyMKiii]

Ok, now we've wandered into my wheelhouse as a precision shooter. Elevation is only part of the equation. The term you'll need to get acquainted with is density altitude. The DA is the measure of how "thick" the air is. Higher DA gives less resistance. Heat, humidity, and elevation all go into DA. Find yourself a hot, dry, and high strip, and you'll notice significantly less drag. On a hot dry day around here (el 5200-ish) we'll see the DA climb up into the 8000+ft range. During a blizzard, it'll plummet to 1500ft. I've never really thought about it for rc, but I've also never gotten over 100mph. I suspect once you push closer to the 200mph mark, you actually need to think in ballistic terms...

Nic Case set his 202 mph record around 2500-2750 ft elevation in St. George Utah. Not the highest elevation but it is a very dry desert region, which all likely helped some.

The area where James McCoy lives is around 922 ft elevation.

 

[Diem Turner]

Ok, now we've wandered into my wheelhouse as a precision shooter. Elevation is only part of the equation. The term you'll need to get acquainted with is density altitude. The DA is the measure of how "thick" the air is. Higher DA gives less resistance. Heat, humidity, and elevation all go into DA. Find yourself a hot, dry, and high strip, and you'll notice significantly less drag. On a hot dry day around here (el 5200-ish) we'll see the DA climb up into the 8000+ft range. During a blizzard, it'll plummet to 1500ft. I've never really thought about it for rc, but I've also never gotten over 100mph. I suspect once you push closer to the 200mph mark, you actually need to think in ballistic terms...

Yeah, that's exactly what I was driving at (pun wasn't initially intended, but once I spotted it I decided to leave it for posterity).

Nic Case set his 202 mph record around 2500-2750 ft elevation in St. George Utah. Not the highest elevation but it is a very dry desert region, which all likely helped some.

The area where James McCoy lives is around 922 ft elevation.

I would wager that at 200mph+ speeds, 1000ft will make a not so insignificant difference. I don't know Richard about ballistics...perhaps @Pat_ranch could help quantify what kind of potential difference that might make in comparison to running at sea level.

 

[LibertyMKiii]

Yeah, that's exactly what I was driving at (pun wasn't initially intended, but once I spotted it I decided to leave it for posterity).

I would wager that at 200mph+ speeds, 1000ft will make a not so insignificant difference. I don't know Richard about ballistics...perhaps @Pat_ranch could help quantify what kind of potential difference that might make in comparison to running at sea level.

We can sort of feel it just walking outside. Seal level to 1000 ft is not that big of a difference. But go walk an incline hill in Denver and you will be huffing and puffing. (my wife's data lives there)

 

[Diem Turner]

We can sort of feel it just walking outside. Seal level to 1000 ft is not that big of a difference. But go walk an incline hill in Denver and you will be huffing and puffing. (my wife's data lives there)

Yes, but I think there's a difference between the need for oxygen and how thick it gets going 200mph. That's just my conjecture though.

Wait...your wife's data lives there? HAS SHE LOST HER MIND?!

 

[LibertyMKiii]

Yes, but I think there's a difference between the need for oxygen and how thick it gets going 200mph. That's just my conjecture though.

Wait...your wife's data lives there? HAS SHE LOST HER MIND?!

Lol oops
ya she lost her mind a long time ago....

Well I mean that you can physically notice the difference in elevation and air density by the reduced oxygen levels. There seems to be little to no difference between sea level and 1000 ft. But when you get above 2000 ft you can notice that oxygen difference. I imagine the air density is changing more significantly at those 2000+ elevations if it were graphed.


Alright here it is!
We need a runway at 79,000 ft elevation!

 

[Diem Turner]

Lol oops
ya she lost her mind a long time ago....

Well I mean that you can physically notice the difference in elevation and air density by the reduced oxygen levels. There seems to be little to no difference between sea level and 1000 ft. But when you get above 2000 ft you can notice that oxygen difference. I imagine the air density is changing more significantly at those 2000+ elevations if it were graphed.

lol...in the past I've sometimes wondered if it was ever there to begin with and "rose tinted glasses" just obscured the view.

Yeah, I feel ya. Like said, I'm just speculating as I don't really have all that much to go on.

 

[LibertyMKiii]

lol...in the past I've sometimes wondered if it was ever there to begin with and "rose tinted glasses" just obscured the view.

Yeah, I feel ya. Like said, I'm just speculating as I don't really have all that much to go on.

Updated my post with real data. You can see the lines are pretty darn close till you reach 2 kilometers above sea level

 

[Diem Turner]

Ok yeah, I just found this graph.

Alright here it is!
We need a runway at 79,000 ft elevation!

Fo shizzle. The one on Everest is uncharitably short.

 

[LibertyMKiii]

Ok yeah, I just found this graph.
View attachment 240367

Fo shizzle. The one on Everest is uncharitably short.

Level / flat ground and extremely high elevation just do not go together sadly. We need the flying aircraft carrier from Avengers.

 

[Diem Turner]

Level / flat ground and extremely high elevation just do not go together sadly. We need the flying aircraft carrier from Avengers.

I think we may have finally solved the mystery of the Nazca Lines...I presume the spirals were used for the tethered speed runners?

 

[Tex Koder]

I think we may have finally solved the mystery of the Nazca Lines...I presume the spirals were used for the tethered speed runners?
View attachment 240368

You just got to wonder how on earth did those ancient folks walk AND scrape/mark such damn Straight lines (for miles!) in those rough terrain back in those times with just some sticks and rocks as guide markers...

 

[Velodromed]

Yeah, I feel ya. Like said, I'm just speculating as I don't really have all that much to go on.

regarding elevation or wives?

 

[Diem Turner]

You just got to wonder how on earth did those ancient folks walk AND scrape/mark such damn Straight lines (for miles!) in those rough terrain back in those times with just some sticks and rocks as guide markers...

It is indeed an interesting question, but perhaps a tribe of Aborigines provides us with a clue. I can't recall what their exact name was but I saw a report on them where they are said to be able to walk in perfectly straight lines indefinitely (pretty much all other humans have a natural tendency to either circle to the left or right). An interesting and unique characteristic of their use of language is that they don't identify an object's position in subjective terms such as left and right, rather, they speak in objective absolute terms when it comes to spatial positioning (i.e. "Would you hand me that pot north of you") which I found fascinating. Now, whether this is coincidental or actually has some bearing on their ability to maintain a given direction is debatable...but to my mind it would make perfect sense that if you are at all times aware of what direction you're facing that traveling in straight lines would be easier by several orders of magnitude.

regarding elevation or wives?

Both. Though, to be more precise, I was referring to my specific knowledge when it comes to the molecular density of air relative to altitude. On point number two, I was only married once so I don't have nearly the same amount of experience as, say, Elizabeth Taylor.

 

[rotauq]

I remember some of us had this elevation discussion like 1.5 years ago. All my speedrun results should get +15% because i am basicly below sealevel

I think the conclusion was just to make a mile long vacuum tube and take elevation out of the equation