Calculates your approx. terminal velocity subject to your riding position (frontal rider surface area in m^2), altitude above sea level at the start of the run (in m) rider's weight (in kg) and the gradient of the slope (in %). Please note that on the right hand side there is a conversion into imperial units.
If you fill out these FOUR fields (IN YELLOW), the spreadsheet automatically calculates your terminal velocity, and time and distance from start point at which you reach it from stationary with no push off. It also assumes that you are skating in a straight line (affects air density and hence the drag), wearing leathers (or clothes with low drag) and skating on a reasonably smooth surface with a constant slope
May be interesting to some.
Comments welcome.
Last edited by IRJohnnyRotten; 06-25-2009 at 02:41 AM..
That's pretty sweet, but you really need to add air resistance to your spreadsheet. You also need to factor in changes in altitude to make that one correct. For instance, there is a hill in Colorado that you can go over 75mph. However, it is at 8000ft where the air is almost 30% thinner. At sea level, that hill would not be nearly as fast.
That's pretty sweet, but you really need to add air resistance to your spreadsheet. You also need to factor in changes in altitude to make that one correct. For instance, there is a hill in Colorado that you can go over 75mph. However, it is at 8000ft where the air is almost 30% thinner. At sea level, that hill would not be nearly as fast.
Air resistance already built in hence you reach terminal velociy... It's one of the parameters that you can modify already I just didn't include it as one of the inputs. Had a play with it and unless you are going down, say from the top of mount it won't be hugely affected. Temperature also is a factor, but I was too lazy to model that. May do in the next revision.
Air resistance already built in hence you reach terminal velociy... It's one of the parameters that you can modify already I just didn't include it as one of the inputs. Had a play with it and unless you are going down, say from the top of mount it won't be hugely affected. Temperature also is a factor, but I was too lazy to model that. May do in the next revision.
Keep the comments coming.
Air resistance is HUGELY affected by different altitudes. I've skated roads at 12,500ft and roads at 12.5 ft, and trust me, there is a difference. For instance, I have gone nearly 60mph on a 3% grade, however that was at over 11,000ft. At that kind of altitude, one guy can be standing up airbraking while another tucks with no difference in speed. Read up on the physics of our atmosphere. Same reason cars are less powerful at altitude: Less Air. Less Air = Less Air resistance = Higher terminal velocity.
Air resistance is HUGELY affected by different altitudes. I've skated roads at 12,500ft and roads at 12.5 ft, and trust me, there is a difference. For instance, I have gone nearly 60mph on a 3% grade, however that was at over 11,000ft. At that kind of altitude, one guy can be standing up airbraking while another tucks with no difference in speed. Read up on the physics of our atmosphere. Same reason cars are less powerful at altitude: Less Air. Less Air = Less Air resistance = Higher terminal velocity.
Sure man. It has an impact. My point was that other factor (e.g body position as mentioned above) have a much larger impact on your terminal velocity than the air density. I'll factor it in the next version though as a lot of people seem to want to see it.
not too familiar with spreadsheets, but the metric to standard conversions didn't seem to be working either.
I've been wondering about how close bearing technology is to the limits of physics.. more of a pressing question at low speeds and flatter ground..
be interesting in general to take some of these theoretical numbers and compare them to carefully measured hills/runs.
This is because 1% slope is a drop of 1ft over 100ft. Negligible. Since the model has friction built in, the lateral component of the force required to get you moving is not sufficient to overcome the friction. Hence it gives you a terminal velocity of 0 i.e. you will not move.
With regard to bearings, Lush has quite a good atricle:
. What will be the result of using these higher grade bearings in Skating Applications ?
The most noticeable result is that you will end up with less money in your wallet and the people that sold you the bearings will be eating out at restaurants at your expense for a few days. Under the following conditions, you may notice an improved performance.
(a) You spend a lot of money (i.e. thousands of dollars) to have your equipment (wheels and board) redesigned and manufactured to suit these high precision bearings. You will need to use some type of shock absorber that allows for absolutely no vibration.
(b) You will have to be prepared to skate on a perfectly smooth surface and make no attempts to use your feet to propel yourself. (Doing so would cause shock loads to the bearings and any extra precision would be lost very quickly).
(c) After you work out how you are going to achieve the above two criteria, you may (and that is only "may") experience a better result than using ABEC 1 bearings after you attain a speed of about 390 KPH (240 MPH) with 65mm wheels and grease lubrication.
Air resistance is HUGELY affected by different altitudes. I've skated roads at 12,500ft and roads at 12.5 ft, and trust me, there is a difference. For instance, I have gone nearly 60mph on a 3% grade, however that was at over 11,000ft. At that kind of altitude, one guy can be standing up airbraking while another tucks with no difference in speed. Read up on the physics of our atmosphere. Same reason cars are less powerful at altitude: Less Air. Less Air = Less Air resistance = Higher terminal velocity.
Considering the human body can't even cope with a 1% change in atmospheric oxygen content the chances that you've gone high enough to experience any real change in drag (without an oxygen tank) is minimal.
Downhill Terminal Velocity Calculator
Re: Downhill Terminal Velocity Calculator
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