dougmeyer
Needs a job
moderated
Posts: 2713
|
posted February 05, 2007 02:51 PM
I almost hate to bring this up.... but,
At some point during that very tedious discussion about "The Maxton Runs" I promised to re-figure the maximum possible speeds with stock gearing. I measured my ME-1 "200" tire very carefully and it is 78" in circumference, minimum. Using this tire and not accounting for any growth (which is negligable) the speeds at the following rev limits are:
11,400 -199.77
11,500 - 201.525
11,600 - 203.278
Now think this through- If you accept the premise that when the rev limiter hits, the bike ceases to accelerate (we can agree on that, right?) NOTHING will make the bike go faster than those speeds at the point the limiter hits.
Wind only effects the ability of the bike either to:
1. Get to the limiter sooner, if at all (tailwind)
or
2. Delay rev limit onset vs. distance, or not get to the limiter at all in the distance required with the power available (headwind).
Now those of you that want to argue #1, consider this; you would have to accept that the wind force can propel the bike faster against, or inspite of, the rev limiter being activated for the bike to exceed these mechanical limits.
A mitigating factor is that if the rev limit is reached as the result of traction loss, the tailwind could reduce this effect, but only to the point that the rev limit comes into play. Traction loss is due to having the power available be insufficient to overcome the aero drag which is a function of airspeed, not ground speed. Wind only effects airspeed and remember, traction cannot be better than zero slip.
Now on the GPS accuracy deal.
I did a little experiment yesterday in the airplane. I figured that one absolute reference point is "stationary" so I taxied at a steady 25 knots and stopped as hard as I could. From the instant the forward motion stopped (as near as I could tell) it took 6 to 7 seconds for the GPS readout to show "0". This tells me that there is at least that amount of delay in instantaneous speed shown due to update rate of the receiver ( and this is using a $70,000 Garmin G-1000 integrated avionics suite).
It's not a big deal but just be aware your GPS speed may or may not be your real speed. It's certainly close enough for bar talk, but not for deciding who's REALLY the fastest.
Doug
  
|
osti33
Needs a job
Posts: 2973
|
posted February 05, 2007 03:06 PM
Thanks for the info Doug. Great bridges article today as well. 
Ryan
|
H2 to ZX12
Needs a job
two stroke power
Posts: 3674
|
posted February 05, 2007 03:22 PM
thanks as well Doug, you answered question that I was afraid to ask :-P, you shed light where there was no darkness lol
|
supra5677
Pro
Posts: 1279
|
posted February 05, 2007 03:23 PM
Hey Doug:
I found the CW article with the bike Muzzy crated and shipped to them. The bike dynoed at 161.6 stock and 168.9 with the muzzy exhaust. The bike was tested 2200 feet above sea level compared to Maxtons 256 feet. Can you tell me how much horsepower is lost per 100 feet.. I'll post the rest of the article later. Bike went 197mph with tail wind and 183.9 against the wind giving an average of 190.4.. Article has some biases.. I'll will elaborate later.
supra
|
dougmeyer
Needs a job
moderated
Posts: 2713
|
posted February 05, 2007 04:03 PM
Normal power loss is 3-4% per thousand feet, or .3 to .4% per 100 feet, so 6 to 8% in the CW case.
|
psycho1122
Pro
Posts: 1608
|
posted February 05, 2007 04:04 PM
Good stuff!! Math looks close to mine...
____________
You say PSYCHO like it's a BAD thing!!
|
psycho1122
Pro
Posts: 1608
|
posted February 05, 2007 04:06 PM
Oh! and BTW Doug, you can always keep the Excellent Bridges articles comming!
____________
You say PSYCHO like it's a BAD thing!!
|
THE ICE MAN
Expert Class
Posts: 195
|
posted February 05, 2007 09:24 PM
quote:
At some point during that very tedious discussion about "The Maxton Runs" I promised to re-figure the maximum possible speeds with stock gearing. I measured my ME-1 "200" tire very carefully and it is 78" in circumference, minimum. Using this tire and not accounting for any growth (which is negligable) the speeds at the following rev limits are:
11,400 -199.77
11,500 - 201.525
11,600 - 203.278
Now on the GPS accuracy deal.
I did a little experiment yesterday in the airplane. I figured that one absolute reference point is "stationary" so I taxied at a steady 25 knots and stopped as hard as I could. From the instant the forward motion stopped (as near as I could tell) it took 6 to 7 seconds for the GPS readout to show "0". This tells me that there is at least that amount of delay in instantaneous speed shown due to update rate of the receiver ( and this is using a $70,000 Garmin G-1000 integrated avionics suite).
It's not a big deal but just be aware your GPS speed may or may not be your real speed. It's certainly close enough for bar talk, but not for deciding who's REALLY the fastest.
Doug
11,400 - 199.77 with a 78" tire circumfrence ??? LOL
Doug just like the busas are geared stock for 200 - 203 mph stock gearing !
Your GPS might be very acurate and expensive but it is very slow, did you actually time the 6-7 seconds on a watch ?? you mean it took you 6-7 seconds to stop !
Everyone who owns a GPS has driven and watched thier gps read the speed they were driving and when going 50 mph and eccelerating quicly to 55 mph the gps takes 1 second to refresh to its curent speed.
If I say I was going 50 mph and I stoped as quicly as I could and when I stoped it took me
7 seconds to stop, I cant say its the gps's fault it took 7 seconds to get to 0 mph
No it would be me an my vehicle to get to 7 seconds.
I bet it you were going 25 knots and ran into a bridge your GPS would show 0 mph in 1 second providing it was still working.
____________
ACE PERFORMANCE.COM
40 Records@ Maxton, Fastest NA
1507cc Busa 223.330 MPH also
Fastest ZX12 N.A.212.846 MPH in
the mile Fastest 1000 750 @ Maxton
& Fastest 600 N.A. in the world.
|
THE ICE MAN
Expert Class
Posts: 195
|
posted February 05, 2007 09:33 PM
Here is the Garmin 72 with WAAS it operates with 12 sattelites
REFRESH RATE IS EVERY 1 SECOND !!!!!!
TOWARDS THE BOTTOM.
Plotter/Moving Map Features
Download PDF Specs
*Requires Adobe Reader 5.0+
Database: Factory preloaded with Marine Point Database (Americas) that contains worldwide cities, navaids, and U.S.A. tide data.
MapSource®: Accepts up to 1 megabyte of data from the optional MapSource Points of Interest CD **
Navigation Features
Waypoints/icons: 500 with name and graphic symbol, 10 nearest (automatic), 10 proximity
Routes: 50 reversible routes with up to 50 points each, plus MOB and TracBack® modes
Tracks: Automatic track log; 10 saved tracks let you retrace your path in both directions
Trip computer: Average speed, resettable max. speed, trip timer and trip distance
Alarms: Anchor drag, approach and arrival, off-course, proximity waypoint, shallow water and deep water
Tables: Built-in celestial tables for best times to fish and hunt; sun and moon rise, set, and location
Map datums: More than 100 plus user datum
Position format: Lat/Lon, UTM/UPS, Maidenhead, MGRS, Loran TDs and other grids, including user grid
GPS Performance
Receiver: WAAS-enabled, 12 parallel channel GPS receiver continuously tracks and uses up to 12 satellites to compute and update your position
Update rate: 1/second, continuous <<----------<<<< RIGHT HERE DOUG MEYER.
GPS accuracy:
WAAS accuracy:
Position: < 3 meters, 95% typical*
Velocity: 0.05 meter/sec steady state
Dynamics: 6 g's
Interfaces: RS232 with NMEA 0183, RTCM 104 DGPS data format and proprietary Garmin®
Antenna: Built-in quadrifilar
Differential: DGPS, USCG and WAAS capable
Power
Source:
External Power, 8-35V;
Two "AA" batteries (not included)
Battery Life: Up to 16 hours
____________
ACE PERFORMANCE.COM
40 Records@ Maxton, Fastest NA
1507cc Busa 223.330 MPH also
Fastest ZX12 N.A.212.846 MPH in
the mile Fastest 1000 750 @ Maxton
& Fastest 600 N.A. in the world.
|
dougmeyer
Needs a job
moderated
Posts: 2713
|
posted February 05, 2007 10:17 PM
No... I started the watch after the aircraft was stopped. I stopped the watch when the speed hit zero. Hey, I could be full of shit here. I'm just relating what I've seen. I just don't see readouts change as quickly as the speed does. I'll call the Garmin tech rep and get settle it.
It really doesn't matter though, because the error can only be "in the favor" of the speed. You can't be going faster than the readout, only slower. If the readout was instantaneous the speed would be exactly accurate. The way I see it it can only lag, not lead. So your GPS speed can only be faster than the readout, not slower. All I'm saying is it's not as exact as clocks. Take a breath.
|
LONNIEMAC
Expert Class
Posts: 225
|
posted February 06, 2007 05:25 AM
Hey Doug, when i watch my direct tv. i can be watching a game and on the phone with my friends with regular cable. and he his game is 3 to 4 secounds in front of mine. sounds like flight time to me also.
|
H2 to ZX12
Needs a job
two stroke power
Posts: 3674
|
posted February 06, 2007 07:34 AM
quote:
It really doesn't matter though, because the error can only be "in the favor" of the speed. You can't be going faster than the readout, only slower. If the readout was instantaneous the speed would be exactly accurate. The way I see it it can only lag, not lead. So your GPS speed can only be faster than the readout, not slower. All I'm saying is it's not as exact as clocks. Take a breath.
don't you mean that your actual speed could only be faster than the GPS indicates?
|
shiphteey
Needs a job
Posts: 2529
|
posted February 06, 2007 09:37 AM
Any time I've run at Maxton and have gone thru pulling hard, a couple/few hundred RPMs before the limiter I trap 202.xx but my GPS keeps showing 200.
A previous event @ Maxton my GPS was consistently 5 mph lower than what Maxton was showing: 199 @ Maxton....194 on GPS, 202 @ Maxton....GPS showed 197....and so on and so on.
I have gone thru Maxton a few times on the limiter.....THAT is when they are showing the same thing: 188 limiter in 5th on GPS....Maxton MPH showed the same.
So yes, there seems to be the ability to kind of "outrun" the gps in terms of refresh rate. I would suspect how one sets up their bike (gearing and aspiration) would have a lot to do with it. Since I am on the button still in 6th it may be pulling harder then, say, a busa or 12 guy who is stock-ish. They may have lower variances.
Also, the 9/10 is about who gets there quicker. Just like in drag racing....so coming thru on the limiter can be beneficial depending on your set-up, wind, etc. So in that type of racing I would venture to guess the GPS has "caught up" significantly since the bike is no longer "pulling".
I came thru @ 194 about 2-300 rpms from the limiter. I had geared for 197. A supersticky tire and a hot day meant there wasn't as much theoretical tire spin as say a cool morning @ Maxton.
My 2 cents.
A.
|
THE ICE MAN
Expert Class
Posts: 195
|
posted February 06, 2007 04:45 PM
quote:
Now on the GPS accuracy deal.
I did a little experiment yesterday in the airplane. I figured that one absolute reference point is "stationary" so I taxied at a steady 25 knots and stopped as hard as I could. From the instant the forward motion stopped (as near as I could tell) it took 6 to 7 seconds for the GPS readout to show "0". This tells me that there is at least that amount of delay in instantaneous speed shown due to update rate of the receiver ( and this is using a $70,000 Garmin G-1000 integrated avionics suite).
It's not a big deal but just be aware your GPS speed may or may not be your real speed. It's certainly close enough for bar talk, but not for deciding who's REALLY the fastest.
Doug
When ecelerating the gps will jump 10-15 mph at a second of course when you take off
from 50-70 mph,then eventually the gps will catch up within 1 mph.
When someone is in the top of 6th gear and their bike is picking up speed at a
much slower rate then the GPS is usually within 1 mph of your exact speed.
GPS's that you can buy from 99.00 and up, I buy the one that has the WAAS enabled with the speed that tells your MPH to the tenth as in 205.7 MPH they do a great job for the price.
Your gps test from 25 knots going to a full stop has nothing to do with using a GPS readings at high speeds, in top gear.
I do not believe it is that slow !
Out of curiosity I will go down the street in my truck at 30 mph and stop then look at the gps and see how long it takes a 160.00 GPS to read 0 mph, and I will let ya know.
All I am saying is the GPS is a very good tool to tell you within 1 mph of how fast you are going in top speed runs, providing your not on a turbo with 300+ h.p. and chop the throttle at
100 mph.
____________
ACE PERFORMANCE.COM
40 Records@ Maxton, Fastest NA
1507cc Busa 223.330 MPH also
Fastest ZX12 N.A.212.846 MPH in
the mile Fastest 1000 750 @ Maxton
& Fastest 600 N.A. in the world.
|
dougmeyer
Needs a job
moderated
Posts: 2713
|
posted February 07, 2007 06:23 PM
 Edited By: dougmeyer on 7 Feb 2007 18:24
H2 yes, of course that's what I meant. It would be that the GPS was lagging.
So, I talked with the head G-1000 guy at Garmin the other day. I learned that I have been in error because of my aviation mindset. I assumed that because WAAS (Wide Area Augmentation System) was not yet available to the airborne equipment, it was not available on the consumer products. Not so, of course. The very sophisticatedG-1000 updates every second. It is of course, WAAS capable, but not WAAS enabled. When WAAS comes on line for the aviation community it will update 5 times per second JUST LIKE YOURS. It is not available because the preciosin approaches are all still being proofed and certified.
As far as the "update" deal goes, the lag is in the resolution of the indicator's readout, not the processors Ours does not read to tenths, only whole knots (we only need that level of accuracy) and does not "skip" ahead to keep up with a changing rate. This is really of no matter to us because we really rely on airspeed, which is supplied by an air data computer/pitot static system. The only time we use a GPS generated speed is for a resultant ground speed.
For you non -aviators, think of it this way- If I'm flying directly into a 100 mph headwind at 100mph my airspeed is 100 (the air flowing over the wings is going 100 mph) but my groundspeed as shown on the GPS will be ZERO, because I am not changing position over the ground (which is what the satellites plot).
That's not really relevant to my doubting the accuracy of ICE MANS'S speed - where I was clearly wrong, but maybe we can all now understand this a little better. Clocks will remain for some time the most accurate measure of speed, but clearly the latest GPS 's give a valid, repeatable number. It is, after all, ultra high speed "clocks" that make the whole GPS technology work at all.
I stand corrected.
Here's a link to a good explanation of the technology:
http://www.garmin.com/aboutGPS/waas.html
Doug
|
shiphteey
Needs a job
Posts: 2529
|
posted February 07, 2007 08:22 PM
Edited By: shiphteey on 7 Feb 2007 20:25
Good to know even the cheapy one I have is WAAS enabled:
http://www.garmin.com/products/etrex/
I tend to get 3 out of 4 satellites here around the DC area. I can't remember if I get all "4" satellites @ Maxton or only 3. @ Bonneville it was definately 4!
Sal, any idea which GPS unit shows in 1/10s of an mph? To clarify, which is the CHEAPEST one! You mentioned "160.00" for the one that shows 1/10....if thats what the prices start for then that really isn't that bad at all, especially if I sell mine! You know how the yellow one rounds to the nearest integer above 100. As we test and tune on top end, things like 202.5 or 203.4 will still show 203 on GPS so a guy like me won't "truely" know his speed to the 1/10 mph. Initially it didn't matter to me but as the speeds get higher and the difficulty in attaining those speeds is GREATER, nuances like an MPH that reads to the tenth seems valuable in accurately being able to tell what mod/shift point/tuck/af ratio/etc worked and what didn't. If it always spits out the same whole number ... well....you get the idea.
A.
|
H2 to ZX12
Needs a job
two stroke power
Posts: 3674
|
posted February 07, 2007 08:43 PM
a huh, I knew those stunt vids were filmed in MD. you are so busted :P
|
shiphteey
Needs a job
Posts: 2529
|
posted February 07, 2007 08:46 PM
I can neither confirm nor deny the allegations at this time.
|
THE ICE MAN
Expert Class
Posts: 195
|
posted February 08, 2007 09:12 AM
Doug, good info on some things, like the display is the lacking culprit not the processor.
Shp, you can buy the GARMIN GPS 72 it's only 160.00
you go to trip computer and gives you 1/10's an a few other displays as time moving,
time stoped, distance traveled, etc.
____________
ACE PERFORMANCE.COM
40 Records@ Maxton, Fastest NA
1507cc Busa 223.330 MPH also
Fastest ZX12 N.A.212.846 MPH in
the mile Fastest 1000 750 @ Maxton
& Fastest 600 N.A. in the world.
|
H2 to ZX12
Needs a job
two stroke power
Posts: 3674
|
posted February 08, 2007 09:51 AM
quote:
I can neither confirm nor deny the allegations at this time.
ok Scooter.......(Libby)
|
dougmeyer
Needs a job
moderated
Posts: 2713
|
posted February 08, 2007 01:35 PM
I think you need all 12 sats for WAAS, no?
|
THE ICE MAN
Expert Class
Posts: 195
|
posted February 08, 2007 04:14 PM
WAAS consists of approximately 25 ground reference stations positioned across the United States that monitor GPS satellite data. Two master stations, located on either coast, collect data from the reference stations and create a GPS correction message. This correction accounts for GPS satellite orbit and clock drift plus signal delays caused by the atmosphere and ionosphere. The corrected differential message is then broadcast through one of two geostationary satellites, or satellites with a fixed position over the equator. The information is compatible with the basic GPS signal structure, which means any WAAS-enabled GPS receiver can read the signal.
____________
ACE PERFORMANCE.COM
40 Records@ Maxton, Fastest NA
1507cc Busa 223.330 MPH also
Fastest ZX12 N.A.212.846 MPH in
the mile Fastest 1000 750 @ Maxton
& Fastest 600 N.A. in the world.
|
|
|
|
|
HOME
NEW TOPIC