wrongway
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posted August 05, 2010 07:24 AM
quote:
10-15mph = 3-4mph boost.....
The 20+mph gusts you guys had was certainly worth around 7mph...
You'd need a good 30-40mph winds to flirt with "Double Digit" gains. Just ask the UK guys who went to JD9.
ok , now I dont believe anything that you claim is scientific . Drag is determined by airspeed and Cd x Area....
Airplanes have always used airspeed vs groundspeed to set safe cruising speeds .
A 20 mpjh tailwind does change the airspeed by -20mph , not 7mph. I have logged airspeed and gps on both cars and bikes and can easily see the effects of changing direction . What you may have seen is that if the wind is not exactly a tailwind , the amount of speed is changed due to the vector . At ground level topology can also change the speed at different locations in a relatively small area .
Roy
  
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Shane661
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posted August 05, 2010 12:16 PM
 Edited By: Shane661 on 5 Aug 2010 23:24
Are we talking about airplanes or motorcycles here? There are a variety of reasons why you can likely not apply this logic equally to both. You have already mentioned one, "ground level topology".
Aside from that, what you are saying has been proven very wrong in practice. Meaning, regardless of the "theory", it does not apply to our land speed application.
But if it did, I would like to congratulate you on going 175 mph on your 197 rwhp ZX-14, over a distance of 1.5 miles, last year at Loring. 
Shane
PS. Another fun test: Let's take a 1 mph vehicle, and give it a 20 mph tailwind (at the landspeed venue of your choice). Then we can see if it reaches 21 mph.
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smokinZX14
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posted August 05, 2010 03:23 PM
quote:
Brenda & I got back to TFA HQ in Sugar Land Tx at 3pm on Wed. Cool to be having coffee with Jim & Jaime in Popham, Maine on Tues am, then BBQ in Texas on Wed afternoon.
I LOVE all this analysis, 8mph here, 5mph there, i ran this here, that there, Jim shoulda, coulda, woulda.
Bottom line is Jim's bike has the hp to run the numbers and it will have more.
Gotta remember he came straight off the dyno, newly designed head, TB's, set & forget CL's,
At the track he had no logs, did no tweaks on gearing or AF.
In retrospect, it was a mistake to run C-44 without logging AF.
I run it without issues at AF=12.0:1, but have holed a piston @ 12.8-ish
It certainly makes the most hp, but needs a lot of fuel at high CR.
And Jims bike is 16.2 to 1 CR.....
____________
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dubious
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posted August 05, 2010 03:41 PM
Edited By: dubious on 5 Aug 2010 23:44
Congratulations Jim, it was a great first attempt with no tail wind, a new motor, new to you bike, and Rickys first try at LSR.
I am glad nobody got hurt. 
I wont' speculate, rather I am confident with more development and tuning, you have the platform to make new records with
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entropy
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posted August 05, 2010 09:36 PM
quote:
quote:
Brenda & I got back to TFA HQ in Sugar Land Tx at 3pm on Wed. Cool to be having coffee with Jim & Jaime in Popham, Maine on Tues am, then BBQ in Texas on Wed afternoon.
I LOVE all this analysis, 8mph here, 5mph there, i ran this here, that there, Jim shoulda, coulda, woulda.
Bottom line is Jim's bike has the hp to run the numbers and it will have more.
Gotta remember he came straight off the dyno, newly designed head, TB's, set & forget CL's,
At the track he had no logs, did no tweaks on gearing or AF.
In retrospect, it was a mistake to run C-44 without logging AF.
I run it without issues at AF=12.0:1, but have holed a piston @ 12.8-ish
It certainly makes the most hp, but needs a lot of fuel at high CR.
And Jims bike is 16.2 to 1 CR.....
yup, 16.2 is high, but Knecum runs it at 17:1
(and sets records  )
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wrongway
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posted August 06, 2010 03:38 AM
quote:
Are we talking about airplanes or motorcycles here? There are a variety of reasons why you can likely not apply this logic equally to both. You have already mentioned one, "ground level topology".
Aside from that, what you are saying has been proven very wrong in practice. Meaning, regardless of the "theory", it does not apply to our land speed application.
But if it did, I would like to congratulate you on going 175 mph on your 197 rwhp ZX-14, over a distance of 1.5 miles, last year at Loring.
Shane
PS. Another fun test: Let's take a 1 mph vehicle, and give it a 20 mph tailwind (at the landspeed venue of your choice). Then we can see if it reaches 21 mph.
I only had a 15 mph tail wind , I left around noon.... bike 189 mph on saturday , no tail wind , then 199 and 202mph on sunday .
I don't have a problem admitting it ... that was with gasoline.
but I did run an honest 202 this year , but it took 30 more hp.
Roy
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Shane661
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posted August 06, 2010 05:07 AM
Edited By: Shane661 on 6 Aug 2010 13:14
That's interesting.....
I believe I ran the first of my 211 runs within 20 minutes of you...it sure seemed like a LOT more than 15 mph. But, as we all know, the winds can change quickly.
Nonetheless, the proof is in the pudding. I will keep any eye out for the conditions where a straight tailwind nets me a 1:1 mph gain. All this talk of tailwinds is pretty funny...it didn't seem to be such a hot topic when last years results were reported.
Shane
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entropy
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posted August 06, 2010 05:20 AM
Edited By: entropy on 6 Aug 2010 13:21
Last year a TFA associate had a lil hand held wind meter, strongest he saw was about 15mph, but he wasn't taking min by min readings.
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Shane661
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posted August 06, 2010 05:29 AM
Edited By: Shane661 on 6 Aug 2010 13:50
quote:
Last year a TFA associate had a lil hand held wind meter, strongest he saw was about 15mph, but he wasn't taking min by min readings.
He must have missed the minutes when It was gusting to much, much higher speeds. 
This is not to say that any particular run was made made at the peak, but the #'s above seem to sit well with my recollection...and weather history.
I am not really into taking sides much. But I do feel that people sometimes skew the data analysis to fit their theories...as opposed to the opposite. Everyone knows the old saying, "those who don't learn from their history are destined to repeat it". Let's all try to keep an open mind, and learn. After all, every debate need not be an "argument"
Shane
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rtbain
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posted August 06, 2010 06:39 AM
Jim,
That bike was singing a sweet song. Absolutely great first event, I know you will learn from it and go faster.
They call it fishing, not catching for a reason.
They call it racing, not winning for a reason.
‘I made a wrong mistake’ Yogi Berra
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Randy
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Phantom13
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posted August 06, 2010 07:42 AM
Wrongway/Roy-
You can "believe" whatever you want.
These are numbers derived over thousands of passes in the 9/10th mile done in every wind and air condition imaginable on a wide spectrum of bikes and riders over the spand of a decade or so.
Hundreds of hours have been spent studying log data and gps results, and the results are rather consistant.
I'm sorry you feel that's not scientific. Call it whatever you want... I'll keep calling it what it really is...
The Truth.
I do like your 1:1 theory, that's the stuff dreams are made of!  .
____________
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before Work is inside the Dictionary."
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Halvefast
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posted August 06, 2010 08:08 AM
Edited By: Halvefast on 6 Aug 2010 16:39
Lesson to be learned, Show up to every event out there cause you never know when the perfect conditions will be available, and all speeds count.
Even at events like Bonneville where you have to run both ways,
who is to say the gods of speed can't give you a tailwind in both directions 
I learned this one the hard way March 09 TxMile, I said "well I can't go any faster without more HP so why go beat up the bike?"
What happens, first time in history we get a huge tailwind at Tx, another racer setup identical to my bike,
we run within 1mph of each other before goes 218 at that event.  I'm proud of him for being able to acheive that kind of speed.
But it still stings, just a little.
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entropy
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posted August 06, 2010 08:11 AM
Last year Loring i did 212 on sat with sidewind; 218 on sun with tailwind.
am i backing up Phantom??? 6mph gain????
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wrongway
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posted August 06, 2010 08:19 AM
the equation for aero drag does not have any factor for wind speed...... airspeed is airspeed.....
Roy
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Phantom13
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posted August 06, 2010 09:27 AM
Roy, I'm confused buddy...
What EXACTLY are you suggesting?
Forgive me if it's obvious, but could you please spell it out for us unscientific folk. =)
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dougmeyer
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posted August 06, 2010 10:36 AM
A theoretical DIRECT and CONSTANT head or tailwind will affect drag (and therefore top speed) by exactly a 1:1 factor. But of course, rarely do you get an exact heading match, so what you get is an average velocity and a resultant effect based on the vector velocity of head or tail / cross wind combination. The other factors that might SLIGHTLY affect the result are smaller effective tire diameter due to crosswind induced bank angle and a slight change in traction due to slightly greater or lesser drag. The aforementioned "other factors" don't appear in an aircraft scenario though, and only effect a wheel driven motorcycle. In an aircraft it is always 1:1 of the actual headwind or tailwind component added or subtracted from the true airspeed giving the groundspeed.
With a wheel driven car you get increased drag due to the slip angle of the steering wheels to correct for the crosswind vector. A bigger side surface area gets a greater side force and then more steering angle.
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oldkawboy
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posted August 06, 2010 10:39 AM
That's exactly what I was gonna say but Doug beat me to it ! :-)
Dan
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Phantom13
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posted August 06, 2010 12:06 PM
Doug, maybe I'm reading this wrong, but are you implying that a direct and constant 10mph tail/headwind will result in a 1:1 change in your 1 mile speed on a bike or are you stating that is the case with aircraft only?
Thanks,
- Mike.
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before Work is inside the Dictionary."
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Y2KZX12R
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posted August 06, 2010 03:31 PM
Edited By: Y2KZX12R on 6 Aug 2010 23:32
Thanks Doug for the explanation. From everything I've read on aeros I knew it was very close to 1 to 1 for a direct tail wind if the bike is pushing up against the imaginary brick wall.
I just didn't want to get into a pissing match on the Internet. And I couldn't explain it.
If someone really wanted to spend some time and do some reading on the topic the info is out there.
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Shane661
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posted August 06, 2010 03:33 PM
Edited By: Shane661 on 6 Aug 2010 23:45
quote:
Thanks Doug for the explanation. From everything I've read on aeros I knew it was very close to 1 to 1 for a direct tail wind if the bike is pushing up against the imaginary brick wall.
I just didn't want to get into a pissing match on the Internet. And I couldn't explain it.
If someone really wanted to spend some time and do some reading on the topic the info is out there.
So Jim, after reading this whole thread, do you still think it is near 1:1 in practice?
Reading theory is great. But real-world track results trump theory every time.
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Shane661
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posted August 06, 2010 04:14 PM
Edited By: Shane661 on 7 Aug 2010 00:15
quote:
Last year Loring i did 212 on sat with sidewind; 218 on sun with tailwind.
am i backing up Phantom??? 6mph gain????
Two good pieces of informatkion here:
Karl, you went about what, 7-8 mph faster with a sidewind than you normally do with equal conditions in the mile at Texas? I know you have never ran near that speed in the mile, sidewind, headwind, OR tailwind. It sure seems like the extra 1/2 mile allowed you to gain some signifincant mph.
Also, as you pointed out, 6 mph gain with the tailwind.
Theory vs. practice...you've gotta love it!
Shane
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dubious
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posted August 06, 2010 05:26 PM
Edited By: dubious on 7 Aug 2010 01:28
.
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Some are not worthy of the effort.
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entropy
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posted August 06, 2010 11:55 PM
ooops,
just checked my log, the 212 was done on sun 9:22am, notes say that tailwind was 5-13, variable direction, when the pass was made.
I have no conclusions other than 1.5 mi means more speed, and tailwinds are good.
But, our Loring tailwind was highly variable in both speed & direction at the starting grid.
I betcha it was all over the place down track also.
sorry for the misinformation
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wrongway
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posted August 07, 2010 04:57 AM
Snane , look at the run log form loring last year , sorted by speed
your run on saturday was 197.001..... a few mph faster than you have ever run at maxon. And sunday magically you ran 211.... 14 mph faster .... and the with a tailwind that was very close to that ...
i went 187.4 on saturday and 202.8 on sunday .... 15.4 mph faster
ali went 220 on saturday and 229 on sunday ... only 9mph faster
greg neal went 179 on saturday and 190 on sunday ... 11 mph faster
looks like records were set with 9- 15 mph tail winds..... or maybe we should conclude that big riders benefit more ?
Roy
quote:
quote:
Last year Loring i did 212 on sat with sidewind; 218 on sun with tailwind.
am i backing up Phantom??? 6mph gain????
Two good pieces of informatkion here:
Karl, you went about what, 7-8 mph faster with a sidewind than you normally do with equal conditions in the mile at Texas? I know you have never ran near that speed in the mile, sidewind, headwind, OR tailwind. It sure seems like the extra 1/2 mile allowed you to gain some signifincant mph.
Also, as you pointed out, 6 mph gain with the tailwind.
Theory vs. practice...you've gotta love it!
Shane
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THE ICE MAN
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posted August 07, 2010 04:59 AM
10 MPH tail wind does not net you 10 mph or close to it !
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