That’s fine, but that’s basically irrelevant to the data dropout issue isn’t it? It seems as if sometimes the Garmin unit just is busy doing other things and completely fails to record a data point (or two or three).
Maybe not. Let me do some testing and see. I think the GPS unit is a big drain on the Edge 500 I have. My suspicion is that it gets in the way of proper ANT+ logging.
But let me check and see. Thanks for your input!
Headwind is the total wind that hits the front of your bike, so it's the sum of wheel speed and wind speed.
Is that standard? I’ve always thought of that as “airspeed” and headwind (or tailwind) as just the wind component.
Headwind is the total wind that hits the front of your bike, so it's the sum of wheel speed and wind speed.
Is that standard? I’ve always thought of that as “airspeed” and headwind (or tailwind) as just the wind component.
No, it’s just the name "headwind’ was … ummm… an artefact of the development process I took for the iBike version of Aerolab. Awww, heck… it was late at night and I was tired, ok? 
So headwind = airspeed in Aerolab. Everywhere else, headwind is the … ummm… head wind.
Cheers!
Andy, thanks for bringing this thread back up. I’ve meant to ask this some moons ago but kept forgetting it: what about track/velodrome runs?
We’re considering booking a closed, 200m track in the upcoming weeks. For testing purposes, I thought of simulating a half-pipe by riding mostly in the lower (“flat”) part of the track, and every lap, in one of the curves, go all the way up, touching the maximum at some specific marking (to give me a controllable point every 200m). The track is not so steeply banked, but we should still have 2-3 meters elevation. Would this suffice?
You won’t need to do this. Stay on the black line. Your CG height will go down in the turns and up on the straights. Level the curve over 10 or 12 laps and you should be ok. Make sure you run at pretty constant speed and level the same portion of the lap (the top of the VE curve on each straight).
This will be good* enough * for **A vs B comparison.
Headwind is the total wind that hits the front of your bike, so it's the sum of wheel speed and wind speed.
Is that standard? I’ve always thought of that as “airspeed” and headwind (or tailwind) as just the wind component.
No, it’s just the name "headwind’ was … ummm… an artefact of the development process I took for the iBike version of Aerolab. Awww, heck… it was late at night and I was tired, ok?
So headwind = airspeed in Aerolab. Everywhere else, headwind is the … ummm… head wind.
Cheers!
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
Let’s use this as a convention, at least in the Platypus thread:
http://en.wikipedia.org/wiki/File:Rollpitchyawplain.png
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
Let’s use this as a convention, at least in the Platypus thread:
http://en.wikipedia.org/...ollpitchyawplain.png
It was all clear to me until I looked at that picture!
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
Let’s use this as a convention, at least in the Platypus thread:http://en.wikipedia.org/...ollpitchyawplain.png
Looks like bike convention follows airplane convention (IIRC), i.e. wind hitting the NDS of the bike corresponds to +ive yaw…
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
Let’s use this as a convention, at least in the Platypus thread:http://en.wikipedia.org/...ollpitchyawplain.png
Looks like bike convention follows airplane convention (IIRC), i.e. wind hitting the NDS of the bike corresponds to +ive yaw…
Here’s a quote from the Cervelo S5 White paper: “The figure above is a yaw-drag chart, a typical way of comparing the aerodynamic drag forces of different bicycles with a rider. Less drag (lower on the chart) is better. The vertical axis shows the drag force in grams, measured along the axis of the bike (not wind axes). This is the opposing axial force the rider feels due to the wind. The horizontal axis shows the yaw angle, or crosswind angle, in degrees. This is the angle the net wind makes with the rider, including both the wind created by the rider’s motion along the riding direction, plus any atmospheric wind (cross wind). Positive yaw (right side of the horizontal axis) is with the oncoming wind on the rider’s right side; negative yaw (left side of the axis) is with the oncoming wind on the rider’s left side.” Is that consistent with the airplane convention?
I’ve only been a pilot for 26 years and I’ve never heard yaw expressed as positive or negative, just left or right.
OK, so since we’re making admissions, what’s the standard for positive and negative yaw? If you’re on a bike and you’ve got a pure headwind, that’s zero yaw. If you then turn slightly to the left so the wind is now slightly on your right, is that positive yaw or negative yaw? Is it the same if you’re in an airplane (i.e., if you yaw to the right, is that positive yaw or negative yaw)?
Let’s use this as a convention, at least in the Platypus thread:http://en.wikipedia.org/...ollpitchyawplain.png
Looks like bike convention follows airplane convention (IIRC), i.e. wind hitting the NDS of the bike corresponds to +ive yaw…
Here’s a quote from the Cervelo S5 White paper: “The figure above is a yaw-drag chart, a typical way of comparing the aerodynamic drag forces of different bicycles with a rider. Less drag (lower on the chart) is better. The vertical axis shows the drag force in grams, measured along the axis of the bike (not wind axes). This is the opposing axial force the rider feels due to the wind. The horizontal axis shows the yaw angle, or crosswind angle, in degrees. This is the angle the net wind makes with the rider, including both the wind created by the rider’s motion along the riding direction, plus any atmospheric wind (cross wind). Positive yaw (right side of the horizontal axis) is with the oncoming wind on the rider’s right side; negative yaw (left side of the axis) is with the oncoming wind on the rider’s left side.” Is that consistent with the airplane convention?
Nope. Perhaps I didn’t remember correctly…I’m sure a search on Mark Cote’s quotes (MITAerobike) might confirm Damon’s statement above.
Looks like bike convention follows airplane convention (IIRC), i.e. wind hitting the NDS of the bike corresponds to +ive yaw…
Here’s a quote from the Cervelo S5 White paper: “The figure above is a yaw-drag chart, a typical way of comparing the aerodynamic drag forces of different bicycles with a rider. Less drag (lower on the chart) is better. The vertical axis shows the drag force in grams, measured along the axis of the bike (not wind axes). This is the opposing axial force the rider feels due to the wind. The horizontal axis shows the yaw angle, or crosswind angle, in degrees. This is the angle the net wind makes with the rider, including both the wind created by the rider’s motion along the riding direction, plus any atmospheric wind (cross wind). Positive yaw (right side of the horizontal axis) is with the oncoming wind on the rider’s right side; negative yaw (left side of the axis) is with the oncoming wind on the rider’s left side.” Is that consistent with the airplane convention?
Nope. Perhaps I didn’t remember correctly…I’m sure a search on Mark Cote’s quotes (MITAerobike) might confirm Damon’s statement above.
Well, the admission I was making was that I’ve been avoiding the terms “positive” and “negative” yaw because I became confused after reading tunnel reports posted here. I think I recall Mark and Damon using the convention in the paragraph above, but the convention used in the Project 96 studies is the airplane convention. So (uncharacteristically) I decided to shut up.
How do I know I have repeatable data? Is it the same CdA # or the wave of the graph looking exactly the same within each session?
Thanks
How do I know I have repeatable data? Is it the same CdA # or the wave of the graph looking exactly the same within each session?
Thanks
Well, if you do things right, no matter what the CdA, all the curves will look like the real elevation. Repeatability should be measured by how consistently the same set-up will yield the same CdA.
Well, if you do things right, no matter what the CdA, all the curves will look like the real elevation.
This is what has me worried. I’m doing a half pipe and I can see the peaks on both sides, but the peaks are not at the exact same elevation each time. If it helps here is a screen shot of my graph:
Thanks for all the help.
You’re off by, what, 20cms per 1km? .2% There must’ve been practically no wind that day. Very nice!
lol. You mean all I had to do was use the scale on the left side of the graph to get some perspective?
Thanks again.
Ummm, yeah.
Congrats on an excellent VE test, BDU.
You’re off by, what, 20cms per 1km? .2% There must’ve been practically no wind that day. Very nice!
Yeah, but it looks like the first 3-1/4 laps may have had very (very) slightly higher CdA than the last 2 laps. Anything change?
