Author Topic: USA Bobsled Team Tests in Wind Tunnel  (Read 10455 times)

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Offline SPARKY

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #15 on: July 22, 2009, 09:39:52 AM »
JL 222  seems like I remember Kents "rant" about knock off copying ---how would that be diffirent  :? :?
« Last Edit: July 22, 2009, 09:43:39 AM by SPARKY »
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Offline joea

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #16 on: July 22, 2009, 09:55:12 AM »
to me its like if Roush got on here and wanted to help us learn
about making hp and torque...........

talking about cylinder head flow... flow benches......etc....and someone
wanted to know how many cfm a prostock head flows.........cant tell us
specifically but can help us understand some physics.....

or how much positive pressure does a prostock airscoop enable........cant
tell us specifically how much is generated after 50,000$ of windtunnel
and flow bench and bodywork.........but could impart some
helpful hints and guidance.........


Offline Geo

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #17 on: July 22, 2009, 10:13:40 AM »
Yes, that's the question you wanted an answer for, however that's not the question you asked.  :-D

The info posted so far has helped me go in the direction needed to be safer than I would on my own and I now can prepare for a trip to the wind tunnel and not waste their time and my money.   :wink:

Geo

Offline Stainless Two

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #18 on: July 22, 2009, 10:30:23 AM »
Go USA!!!!  Also, I really enjoy reading about the testing, and also watching the videos on youtube. Please do not take tongue in cheek posts personally, without them the content may get very dry...Just yesterday, I showed a friend of mine the video of the bub liner in your tunnel, and the Saving Abel vid as well to show him some footage of a true dumbass in NASCAR.  I mean, what an idiot...

The more the merrier!!!!!!!    :cheers:
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Offline jl222

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #19 on: July 22, 2009, 11:17:35 AM »
to me its like if Roush got on here and wanted to help us learn
about making hp and torque...........

talking about cylinder head flow... flow benches......etc....and someone
wanted to know how many cfm a prostock head flows.........cant tell us
specifically but can help us understand some physics.....

or how much positive pressure does a prostock airscoop enable........cant
tell us specifically how much is generated after 50,000$ of windtunnel
and flow bench and bodywork.........but could impart some
helpful hints and guidance.........



  Joea
 I'm not asking specifically, if you notice a prostock spoiler they are ran almost flat, so the pressure difference between the top and bottom is were the downforce comes from. In our case, a 10 x 53 spoiler =530 sq in. if there was 1 lb of psi less at the bottom that would be 530 lbs of downforce. If I knew ''approximately'' what it was I could have more info to lobby for a rule change to allow longer spoilers. 5 more in. at 1 lb psi
= 265 more lbs or total of 795 lbs. This would allow us to remove weight and kinetic energy.
 Then there is Gurney flaps.
 Maybe somebody here knows this info, or a prostock crewchief.

        JL222 :cheers:

         

Offline A2WindTunnel

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #20 on: July 22, 2009, 12:09:16 PM »
Quote
  The one question I had was how much pressure difference between the top and bottom of a NHRA prostock spoiler '' not whose'' your reply was you could not give out information others had paid for.

   So much for helping us out.

    My reply was this '' ''

    JL222
   


All I can say is that I try to help as much as I can without getting fired from my job and (I hate to say) as politically correct as possible to keep all parties satisfied.  You NEED to understand there are confidentiality agreements that we sign with teams that test in the tunnel and if I were to talk about something learned at a test I could lose my job and could potentially have a law suite against A2 because of a little piece of paper called a contract.  We take this VERY seriously at both tunnels ( AeroDyn & A2) and don’t care how many stick and stones thrown or eye rolls I get, I will NOT talk about other team’s data or information with out permission from them because that is information they paid for their personal use.  There is a reason that more wind tunnels are not on here writing about information because they don’t want to deal with walking a line of what they can talk about and what they can’t then getting slammed for not telling someone what they want to hear.  I am walking a fine line by being on this website to not give our customers the wrong idea.  If I were a University student of professor that had access to a wind tunnel that I could run my own studies then that is a different story.

I can talk about general aero related questions and have been pretty specific in the past about some posts.  If you have a question about a configuration any team has tested then that constitutes information that a team paid for to find the answer no matter how general you think it is.  Are there some questions I can be more specific on? Absolutely.  Do I have the time during my day to spend hours on here to answer all questions in the way they deserve in great detail? NO, but I know that for every person I do answer there will be one or more that is mad that I didn’t answer theirs in the way they felt I “should” answer.   

There is no magic number for me to say well in the history of the NHRA 100% of pro stock spoilers have X amount of pressure difference from top to bottom.  Bodies change, rules change, different manufactures have different things going on with the shapes of the car, scoops, spoiler angle, spoiler with wicker or without, underbody, fender shape. Even the lateral and longitudinal pressure distribution on a spoiler is not the same from left to right.  With so many variables there I can’t just say X is the value you are looking for.  If you think that is no help then you are not paying attention to what I am trying to educate you on. ALL of those variables will make a difference in the pressure reading you are asking for so I cant be general because I would have to tell you more information then just a single number.  You can’t assume that one car has this aero characteristic so my car must be the same since it has 4 wheels and a spoiler. And that 1 single number will represent the pressure difference on a spoiler is the same for all is not a good assumption. 

I will ask a similar question to you that you asked to me.  What is the pressure inside a balloon? Or have a look at this picture and tell me what single pressure best describes the loading in the wings of this aircraft?



If it is a general question then please be a little more specific in what you want to know and why and maybe I can give you a general answer without a breach of my contract.  I guarantee that the pressure difference is not the same as on your car as it is on a pro stock, so if this is something of great interest to you and you want to know the answer to help you better understand what is going on with your car then I recommend you do what all racers do.. R&D. Find a way to measure what is going on at the EXACT location you want to know so that you can get on here and tell all of us. On this (Year) (model) car in this (detailed) configuration at this location x inches behind and x inch below the rear spoiler at this angle and this dimension. This is the pressure I recorded.  If you need help on how you could do this, I’m always available to help the best I can (give me a call) I might be able to be a little more specific on the phone then in an open Forum.

I appreciate the positive response from most of the members that I have got in phone calls and email.  I will continue to help as much as I can, and if some of you expect me to just give out information because you feel you deserve them, then you are mistaken and I am not on here to give away information or something you might think of as general, but I signed contract stating that I would not talk about because someone tested it in the tunnel.  Put it this way… If you came to the tunnel and spent $5000 to learn and develop your car, would you be okay with me getting on this forum and openly talking about your test, what you did, what you learned in detail?  I think you would want the same respect I give all our customers.


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Offline fredvance

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #21 on: July 22, 2009, 01:50:24 PM »
I understand your position compleately. As I said before thanks for what you can and do put out. Here is a short question, roughly speaking how much slicker, aerodynamically, is a well waxed surface.

    Fred
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Offline joea

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #22 on: July 22, 2009, 02:55:00 PM »
very cool stuff.....hopefully we can get jl22 closer
to the understanding he is passionate about .....

as it can be so useful for so many...


Offline A2WindTunnel

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #23 on: July 22, 2009, 03:49:50 PM »
Quote
I understand your position compleately. As I said before thanks for what you can and do put out. Here is a short question, roughly speaking how much slicker, aerodynamically, is a well waxed surface.

    Fred

Depends on if it is a Car (bluff bodied object) where the pressure drag far out weighs the skin friction drag.  In this case you might see a very small measurable difference (depending on the car) but it would be very small improvement if any.  Say your skin friction accounts for 5-8% of the overall drag and waxing helps that % by a small percentage.  Now you are talking about a fraction of a % improvement.

If you have a streamliner skin friction becomes much more important because it accounts for bigger % of the overall drag of the vehicle. Things like wax could be more of an improvement on this type of vehicle.

I can talk about this.  I have seen NASCAR racecars in the wind tunnel with paint, primer and bare metal and it is not a significant change in drag because the pressure drag dominates the skin friction on those cars.  I have also seen a team spend hours waxing a car to only have the data repeat from the previous non-waxed run.  Hope this helps.
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Offline A2WindTunnel

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #24 on: July 22, 2009, 03:55:24 PM »
Quote
if they fart in that tunnel he'll post about it..... maybe slim should see if they'll put up a paid banner...
kent

I have been at the tunnels for 5 year and have tested over 15,000 hours with racecars and can tell you that for every "fart" I write about there are 2000 that I cant talk about.

I can tell you that there is a low pressure area where the bobsled crew sits and if one happens to fart... it will stay in the compartment with the others during a run.  This was confirmed in the tunnel with a smoke wand and by the team if you get my drift...

 :-D

.
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Offline fredvance

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #25 on: July 22, 2009, 04:04:28 PM »
I wish I had your answer before I spent most of the afternoon waxing my bike body stuff.lol Oh well it sure looks better. :-D And thanks for the help.

   Fred
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Offline A2WindTunnel

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #26 on: July 22, 2009, 04:24:19 PM »
Quote
I'm not asking specifically, if you notice a prostock spoiler they are ran almost flat, so the pressure difference between the top and bottom is were the downforce comes from. In our case, a 10 x 53 spoiler =530 sq in. if there was 1 lb of psi less at the bottom that would be 530 lbs of downforce. If I knew ''approximately'' what it was I could have more info to lobby for a rule change to allow longer spoilers. 5 more in. at 1 lb psi
= 265 more lbs or total of 795 lbs. This would allow us to remove weight and kinetic energy.
 Then there is Gurney flaps.

I am always happy to help when it comes to safety and other info and all of this information should have been part of your original question.  Again, Aero is not that simple to assume that everyone would benefit from this and x psi on a pro stock would be this much lbs on your car.  If it were that easy us wind tunnels would be out of business. 

I can say this.. In my opinion (take it for what it is worth) I always have a difficult time with a rule or safety change without any empirical data to back it up.  You’re assuming that this extra downforce would be great, but the force changes with velocity squared.  Is that 265lbs more at 100mph, 200mph, 300mph?  Is the car producing lift on the front?  Will this added rear downforce create a moment on the front that would produce more lift making it unstable or even airborne on the front?  These are the types of questions that need answering and I say this in a lot of posts, but NO 2 Racecars are the same.  Without testing you can’t assume a result for every type of car out there, and things you do to the front or rear of a car aerodynamically can affect the balance of the other end.

There are plenty of LS racers that come to the tunnel.  If it is a rule change you guys are looking for then maybe you could ask each of them that would be willing to get a delta pressure across their spoiler to establish a data base for the different style cars to base any decisions on.  Or see if someone is willing to run with a longer spoiler to see the affect on their car.  This is easily done in the tunnel by adding an extension to an existing spoiler. 
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Offline A2WindTunnel

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #27 on: March 03, 2010, 11:11:41 AM »
Team USA won a Gold medal in the 4-man bobsled after a 62 year winless streak!!



Read More at:
http://www.bodynbobsled.com/



D
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Offline mtkawboy

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #28 on: March 03, 2010, 04:23:33 PM »
I watched NASA spend a day testing metal pucks of different metals for the bobslded runners at a skating rink in Cleveland. They would launch them off a platform and see how far they would slide. They had all kinds of different coatings on them but wouldnt discuss anything. Yes that NASA, your tax dollars at work

Offline holdfastgreg

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Re: USA Bobsled Team Tests in Wind Tunnel
« Reply #29 on: March 04, 2010, 02:18:38 PM »
Years ago I worked for a composite and geometric design firm here in Greensboro NC called Envision: Concept Developments.  We had a contract with the US Olympic Committee to build tool and produce beta bobsleds.  They had them tunneled somewhere in NC perhaps that was you?