(Note: LANDRACING.COM donations are not tax deductible)


This is a public forum. The opinions expressed here don't
necessarily reflect the feelings of The Folks That Run The Site (that's us)
unless we explicitly say so, ok?


Author Topic: Simspeed UWD LSR Design Project  (Read 17796 times)

0 Members and 1 Guest are viewing this topic.

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #45 on: July 29, 2019, 11:16:24 PM »
Terry:

I think in this case we're dealing with the real world as opposed to theory. While a yaw string may work with an aircraft, even a high speed one, there is a lot more space and time between the aircraft and the ground than there is between a lsr vehicle and the ground. When something does go sideways and the adrenaline does start to flow even heavier is the driver going to concentrate on a piece of string or where he's going? The Wright brothers were travelling at a little less than 400 mph.  :-D :-D :-D

The driver of a vehicle is very slow to react to instrumentation as compared to what he can see around him and will probably look right through a close up piece of string to the ground he is about to cover at very high speeds, whether in a straight line or tumbling.

Pete
Hi Pete,
 :-P No doubt about the Wright bros speed...LOL.  I feel whether the driver is DIR seeing the yaw change between his position and the nose of the car or DIF reacting to the change in air flow as indicated by a yaw string he's reacting to what he sees in front of him based on the sensitivity of how the change in position is presented to him.  Altitude or distance to the ground as experienced in flight isn't an issue in my opinion. 

Based on what I now understand about a yaw string, meaning how it works to indicate what's happening at the rear of the car in minute detail, this indicates to me its a highly sensitive instrument a DIF driver can use to react quickly to yaw conditions in an attempt to keep the car under control.  Is that as good as a DIR driver experiences?  I don't know of course because I have no seat time fore or aft...but does anyone here who does know that it's not?  Like you I've heard driving from the rear is safer and affords greater control but do we know of anyone whose driven a DIF car using a yaw string?  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #46 on: July 29, 2019, 11:28:08 PM »
Further to Peter's comments..
Yaw in an aircraft is of little consequence--not so in LSR.
When landing in a cross wind does the pilot pay attention to the ?yaw string? or the world around him?

Hi IO,
I'm not trying to create a direct analogy between the two although that's what my comments sound like.  All I'm saying is that a yaw string in a DIF application would act as a useful indicator of changes in attitude at the rear of the car that the driver could react to in lieu of the seat of the pants feel from a DIR or DIM driving position.  In those positions (I'm supposing) what the driver feels is largely based on what he sees in the change in relationship between his position, the nose of the car, and the horizion out his canopy.  In the DIF car the angle of change is largely unknown due to the driver's position relative to the nose and horizon but a yaw string offers real time info of those conditions he can use just as quickly and effectively as a DIR driver would once he understands the value of what he's seeing through his canopy.  All of that is supposition on my part of course but its based on the reality of how a yaw string works and why.  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #47 on: July 29, 2019, 11:35:33 PM »
Re: "Yaw String"

Terry, I became familiar with a yaw string when I was taking glider lessons in Babenhausen, Germany back in '62. The Babenhausen Aero Klub flight instructor was a WW II Messerschmidt fighter pilot. The club trainer was a 2-place glider with him sitting in the rear and me sitting ahead of him. The first few flights were fun even though the English/German language was a real problem. On one flight he wanted to demonstrate how to settle the glider for a landing even from a too- high approach to the field, a large open area adjacent to the woods.We flew for a short time and he brought the plane in on a very high approach over the woods when he suddenly kicked it into a very large yaw angle. The yaw string looked almost sideways and we dropped like a rock until the altitude was a normal approach and he straightened out and landed. That unannounced maneuver scared the crap out of me.  I sure never forgot that yaw string!

Regards, Neil  Tucson, AZ

HI Niel...good story.  Any indicator is only as good as the pilot/driver who understand them and knows how to apply the info to the performance of the vehicle he's flying/driving.  A yaw string in this application gives instantaneous information to the driver of the nose/tail relationship relative to the intended path as indicated by the change in airflow around the nose.  Whether or not that's as useful as what a DIR driver sees and experiences from those positions is unknown to me at this time but the logic of how a yaw string functions is not lost on me.  I'm interested in learning more of real world experiences from someone whose use a yaw string from a DIF ride.  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #48 on: July 29, 2019, 11:43:58 PM »
If anyone has a link to an accurate aerodynamic hp to speed calculator I'd appreciate a share.  I've looked at all I could find through Google and the results vary widely.  Do any of the calculators you've use correlate well to actual speeds of your car or bikes? I'm using the following inputs to base line this design:
Cg = .09
FA = 5.261
Weight = 4000
Speed = 600 mph

Thanks... Terry

Hi
  I have a program called Bonneville Pro by Racing Secrets a drag race results program modified for Bville. Pretty accurate except for acceleration rates '' to quick'' chart to put in cd, frontal area, weight,
tire width, gear ratio, tire roll out, and hp.  Gives a result chart with time, rpm distance and mph. Also wheelspin if to much hp for wheel width. Needs a downforce in put. Maybe newer versions have it.
 
 I  put all that data from Summer Brother's streamliner and it came out on the money.
 425 mph with 2400 hp.

  So unless your streamliner is way more aero you're going to need a lot more hp than 2400 to go 600 mph.

                    JL222

           
Hi JL222,

Good to know!  Here's additional data of this design based on your comments above:

Tire width: 6"
Gear Ratio: 1:1
Wheel roll out: 73.7" or 23.5" diameter
HP is the unknown I'm looking to identify based on these other parameter.  Can you calculate HP from that all that info?  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #49 on: July 29, 2019, 11:50:37 PM »
Terry,

Please listen to Pete, Stainless and Interested Observer about the Yaw String.

Remember the air is fluid, the ground is not.

If you really would like a nice long type of Yaw String with lots of seat feel,
place the drivers compartment in the rear of the vehicle. Then the length of
the car is your Yaw String. Just a suggestion.

Tom G.

Hi Tom G.,
Thanks for the tip... Your comparison is notable in relation to my argument.  The reason I'm leaning to the DIF geometry is the 22% reduction in frontal area for the current design when compared to previous designs I've worked on with DIM and DIR positions.  If in fact use of a yaw string gives useful car attitude info to the DIF driver then applying that to reduce the FA is a no brainer to me.  It has to be proven of course so I'm remaining open to the proposition until I learn definitively from someone that's tried it that its not.  Thanks... Terry.

Offline salt27

  • Hero Member
  • *****
  • Posts: 1402
  • Age: 62
  • Location: S.W. Orygun
Re: Simspeed UWD LSR Design Project
« Reply #50 on: July 30, 2019, 01:18:39 AM »
I believe that there was a streamliner that had a sort of a pole extending from its nose strait forward so the driver could sight down it and know if things were getting out of shape.

I didn't see it in person but read about it.
Does anyone else remember this?

  Don

Offline RidgeRunner

  • Sr. Member
  • ****
  • Posts: 797
  • Location: Ashfield, in the Territories of Western Massachusetts
Re: Simspeed UWD LSR Design Project
« Reply #51 on: July 30, 2019, 05:45:21 AM »
     Yes.  Athol Graham's "City of Salt Lake" when rebuilt after his fatal crash.  There has been much discussion since on exactly what happened but in my opinion the driver's position, while maybe not the total cause, certainly was a major contributing factor.

     First time my new '71 Ford van got loose in the snow on me I was almost sideways before I realized what was happening.  This after 10 winters of driving cars and trucks with more conventional seating locations.  I realized real quick that when sitting almost on top of the pivot point a lot of "natural feel" is lost.

     FWIW, when my buddy took his tank bodied lakester - driver's position at the very front - to Speedweek in '72 the inspector strongly suggested installing some kind of vertical indicator for reference out in front of the driver's line of vision.  He said he had lost a very good friend and something like that might have helped prevent that loss.

      For sure an area worthy of serious consideration during the design phase of any LSR car.

                         Ed

                   

     
« Last Edit: July 30, 2019, 05:46:56 AM by RidgeRunner »

Offline Interested Observer

  • Sr. Member
  • ****
  • Posts: 395
Re: Simspeed UWD LSR Design Project
« Reply #52 on: July 30, 2019, 08:10:43 AM »
1) Yaw string - forget it.  It indicates airflow direction, not vehicle/terrain orientation.
2) What keeps the orange front axle housing from itself rotating and allowing uncommanded steering input?

Online manta22

  • Hero Member
  • *****
  • Posts: 3482
  • Age: 80
  • Location: Tucson, AZ
  • What, me worry?
Re: Simspeed UWD LSR Design Project
« Reply #53 on: July 30, 2019, 11:01:34 AM »
Back in the 1930s, the two dominant Grand Prix cars were Mercedes-Benz and Auto-Union. The Mercedes had a conventional layout while the Auto-Union placed the driver much farther forward. The consensus was that the A-U cars were more difficult to drive because that driver's position gave him less feedback about the car's yaw angle. Ultimately, Bernd Rosemeyer was killed on the Darmstadt autobahn during a speed record attempt

Regards, Neil  Tucson, AZ
Regards, Neil  Tucson, AZ

Offline salt27

  • Hero Member
  • *****
  • Posts: 1402
  • Age: 62
  • Location: S.W. Orygun
Re: Simspeed UWD LSR Design Project
« Reply #54 on: July 30, 2019, 11:41:40 AM »
     Yes.  Athol Graham's "City of Salt Lake" when rebuilt after his fatal crash.  There has been much discussion since on exactly what happened but in my opinion the driver's position, while maybe not the total cause, certainly was a major contributing factor.

                         Ed


Thanks Ed, but not the car I was thinking of.

What I think I remember was the race officials not letting this car run until they devised an indicator of sorts.

Then again it could have been a dream.   :-D

  Don
                   

     

Offline Sumner

  • Global Moderator
  • Hero Member
  • ***
  • Posts: 4067
  • Age: 75
  • Location: Blanding, Utah
  • Blanding, Ut..a small dot in the middle of nowhere
    • http://purplesagetradingpost.com/sumner/sumnerindex.html
Re: Simspeed UWD LSR Design Project
« Reply #55 on: July 30, 2019, 01:15:39 PM »
..
     First time my new '71 Ford van got loose in the snow on me I was almost sideways before I realized what was happening.  This after 10 winters of driving cars and trucks with more conventional seating locations.  I realized real quick that when sitting almost on top of the pivot point a lot of "natural feel" is lost. ...

Same with a '68 chevy van in Wyoming.  It could do 360's in a heartbeat on an icy road.  Never had the same problem with any other vehicle in the same conditions.

A good driver, and you are going to need a great one if you are planning on running even over 400, is going to feel what is going on in 'his butt' way before he is going to visually see it.  This is true at even regular highway speeds.  Next winter take your car out and push it in snowy conditions with a yaw string and see if you feel what is going on body wise vs. sight wise first and which allows you to compensate.

I feel a lot of people don't have any idea how much a car has to be driven on the salt.  Straight line on a flat surface, surly can't be hard to drive right?  But, watch in-car videos and see how much people's hands move and the wheel moves on any car that can over power the salt.  You are reacting way faster than you could by watching something visually and then correcting.

Moving the driver in front of the front wheels undoubtedly offers aero advantages but if the car can't be driven safely what is the point.  A driver that is sitting very closely behind the front wheels is in a tougher driving situation vs. one sitting further back.

================================

With the Summer Brother's car if the figures are accurate it would of taken them 3900 HP to run 500 (probably about what the Turbinator used to run 500).  To run 600 they would of needed 6700 HP.  You don't only need the HP but the parts that won't break using that much HP and a track long enough to get it to the desired speed.  Pretty unbelievable that the Turbinator was able to have a 503 exit speed in 5 miles and they have been doing this for a couple family generations now  :-D.

Sumner


Offline RidgeRunner

  • Sr. Member
  • ****
  • Posts: 797
  • Location: Ashfield, in the Territories of Western Massachusetts
Re: Simspeed UWD LSR Design Project
« Reply #56 on: July 30, 2019, 01:31:03 PM »
     Might not be a dream Don, I also think I remember a "lawn dart" style with a single indicator on the nose in more recent years, red in color?  Couldn't remember any details so didn't mention it.

     Then again could we both have been on the same barley pop recipe at the same time once?   :cheers:

                   Ed

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #57 on: July 30, 2019, 01:54:11 PM »
1) Yaw string - forget it.  It indicates airflow direction, not vehicle/terrain orientation.
2) What keeps the orange front axle housing from itself rotating and allowing uncommanded steering input?

IO,
1) Changes in airflow direction along the nose that diverge from the intended straight line path are in fact a primary indicator of changes in vehicle/terrain orientation.
2) The A-frames limited by shock absorber travel which in this case is roughly 2" total.
Thanks... Terry
« Last Edit: July 30, 2019, 02:21:33 PM by Simspeed »

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #58 on: July 30, 2019, 02:01:18 PM »
Back in the 1930s, the two dominant Grand Prix cars were Mercedes-Benz and Auto-Union. The Mercedes had a conventional layout while the Auto-Union placed the driver much farther forward. The consensus was that the A-U cars were more difficult to drive because that driver's position gave him less feedback about the car's yaw angle. Ultimately, Bernd Rosemeyer was killed on the Darmstadt autobahn during a speed record attempt

Regards, Neil  Tucson, AZ
Hi Niel,
I certainly agree with you and others that lack of yaw feedback to the driver in a DIF position makes safely controlling the vehicle at speed much more difficult.  I'm not attempting to say otherwise.  All I'm proposing is that if a yaw indicator of sufficient fidelity is available to the DIF driver, then logically he should be able to react just as quickly to input corrective steering control.  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 317
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #59 on: July 30, 2019, 02:07:44 PM »
Next winter take your car out and push it in snowy conditions with a yaw string and see if you feel what is going on body wise vs. sight wise first and which allows you to compensate.

I feel a lot of people don't have any idea how much a car has to be driven on the salt.  Straight line on a flat surface, surly can't be hard to drive right?  But, watch in-car videos and see how much people's hands move and the wheel moves on any car that can over power the salt.  You are reacting way faster than you could by watching something visually and then correcting.

Moving the driver in front of the front wheels undoubtedly offers aero advantages but if the car can't be driven safely what is the point.  A driver that is sitting very closely behind the front wheels is in a tougher driving situation vs. one sitting further back.

Sumner

Hi Sumner,
Good suggestion about testing the effectiveness of a yaw string in icy highway conditions.  Not sure if its applicable along a relatively flat car windshield.  I'd think a yaw string would work best on a narrow and tapered cockpit canopy as found in gliders, fighter jets, and streamliners.  As stated previously, I definitely agree that a forward driver position is harder to drive all things being equal. Thanks... Terry
« Last Edit: July 30, 2019, 02:09:20 PM by Simspeed »