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Author Topic: Simspeed UWD LSR Design Project  (Read 17792 times)

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Offline SPARKY

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Re: Simspeed UWD LSR Design Project
« Reply #75 on: July 30, 2019, 10:49:09 PM »
 Yeah, until there is a side wind or gust.  You can bet the driver is going to be focused on the far horizon, not some string two feet in front of him.


If you had ever flown a glider much you would not make that statement

I have used yaw strings on the salt flat  it registers while you are looking at floating mountain
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Offline thefrenchowl

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Re: Simspeed UWD LSR Design Project
« Reply #76 on: July 31, 2019, 09:34:53 AM »
I'm with Peter Jack as far as where to look out when riding or driving...

On a bike, I look as far forward as possible... And the faster the furthest...

In a car, same!!!

For anything that's near, I just rely, like the birds and my cat, on movement or change of status, that's what peripheral vision, no matter how blurred, is for...

Same for butt feel, that's the only way, added with sense of balance in your ears and spacial geometry.

Lots of guys/gals don't have it, them the ones that will crash if they try too hard without these essential feedback loops...

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Offline Seldom Seen Slim

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Re: Simspeed UWD LSR Design Project
« Reply #77 on: July 31, 2019, 09:46:29 AM »
As I had it put during an on-track bike school:

Look down the road/course at where you're going.  It's too late to do anything about where you are right now - you should have seen it coming while you were looking ahead.
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Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #78 on: July 31, 2019, 10:34:32 PM »
I'll spare everyone else the bother and tell you that's John Cobb sitting in the Railton Special, later the Railton Mobil Special.

Cobb held the unlimited LSR, briefly, in September 1938 at 353 MPH, then again between August 1939 and September 1947 at 369 MPH.  In September 1947 Cobb raised the record to 394, including one run at 403.  Breedlove, Donald Campbell, and the Summers Brothers went faster, using different means of propulsion, in 1963, 1964, and 1965, respectively.

Thanks for the interesting thread!

Thank you TD for this info.  I've read through the coverage and videos of Cobb and Campbell's LSR efforts and I'm frankly amazed at the speeds they achieved given the technology of their time.  Both their cars use a DIF layout without a stabilizer fin and didn't seem to suffer from a lack of control until Campbell's 350 mph crash due to what he described as soft salt conditions.  Addition of a fin to the Bluebird rebuild helped him to capture a record two years later.  Any ideas why the DIF of these two cars didn't appear to affect driver control?  Thank... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #79 on: July 31, 2019, 10:36:49 PM »
Yes, first over 400 mph, 13 years before Mickey Thompson.

As far as I know the Railton Special never crashed.

John Cobb died trying to break the World Water Speed Record. Much more dangerous ...
Quite the accomplishment I'd say Tricky. Thanks for sharing... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #80 on: July 31, 2019, 10:43:53 PM »
By the time you feel yaw in such a forward cockpit you'll already be out of control and way too far gone to correct. The same goes for the string.

Pete
I agree with your statement Pete...if a DIF driver is basing his steering decisions on "feel" alone then he is definitely at a disadvantage to a DIR driver.  I have to disagree about the string being the same...logically, the string is a real time indicator of yaw attitude change and its usefulness depends on the drivers ability to incorporate the info its generating in real time along with all the other visual and sensory clues he's experiencing at the front of the car.  Cobb and Campbell proved the DIF position can be used successfully.  Thanks... Terry.

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #81 on: July 31, 2019, 10:50:28 PM »
Terry , frontal area may be less important than a person would think . Knowledgeable people have said here that most (80%?) of the drag of streamlined cars is skin friction .

Hi John,
I have no reason to believe skin friction doesn't generate drag as you say.  Whether or not a short car with larger frontal area generates less total drag than a long car with less frontal area can only be determined through comparative testing.  We'd probably agree a short car with less frontal area would be the best scenario overall but in this project example that's just not an option given the space taken up by the powerplants and supporting systems.  Thanks... Terry.

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #82 on: July 31, 2019, 11:05:04 PM »
The minimal separation of the Heim joints at the forward end  of the upper A-arm effectively constitute a pivot point that, in conjunction with the Heim on the aft end of the lower A-arm, would allow the ?steering knuckle? to rotate about the connecting axis, likely producing unwanted steering effects and probably a god-awful speed wobble.

Hi IO,
Sorry but your description of the rigidity of the front suspension geometry isn't accurate in my opinion.  The a-frames are each triangulated in the shown layout.  There will be no side to side movement through the heim joints other than the clearances allowed to exists between the ball centers and the mounting flanges.  As far as rotating about the connecting axis that's just suspension travel through whatever range of motion the shocks and bump stops are preset to allow.  You're supposed "god-awful" speed wobble is based on what exactly? 

Let's open this up to everyone's determination of your claims.  Who agrees with IO's take on the front suspension as shown and why?  If I'm wrong I'd surely like to know who thinks IO's take is correct and why. Thanks... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #83 on: July 31, 2019, 11:10:07 PM »
Terry:

This continues to be a really interesting thread because there's lots of interesting input being considered in so many different ways. A project such as this needs people who may tend to err on the conservative side and probably always will. There are also the dreamers who come up with the really great ideas which may need at times to be toned down or refined for practical application.

Keep up the good work coordinating this whole thing. We finally have a dreamer who's fun to work with.  :cheers: :cheers: :cheers:

Pete

Thanks for your encouragement Pete.  I'm counting on getting honest opinions and constructive criticism from folks like you whose experiences and success far exceed my own.  I won't hesitate to argue my own positions but I'm certainly open to being educated about things I don't completely understand and altering my views accordingly.
 Thanks... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #84 on: July 31, 2019, 11:16:57 PM »
Yeah, until there is a side wind or gust.  You can bet the driver is going to be focused on the far horizon, not some string two feet in front of him.


If you had ever flown a glider much you would not make that statement

I have used yaw strings on the salt flat  it registers while you are looking at floating mountain
Thanks Sparky...that's the expectation my arguments are based on.  I'm thinking that subconsciously the string movement will translate into reactive adjustments on the steering controls by the driver.  A side wind or gust will no doubt impact the car but in doing so the string will show a corresponding yaw movement that indicates the proper corrective action by the driver.  Thanks for helping to confirm an experience that I've been hoping to find... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #85 on: July 31, 2019, 11:25:03 PM »

For anything that's near, I just rely, like the birds and my cat, on movement or change of status, that's what peripheral vision, no matter how blurred, is for...

Same for butt feel, that's the only way, added with sense of balance in your ears and spacial geometry.

Patrick

Hi Patrick,
I quite agree with your assessment as a whole.  I believe it is the combination of all sensory inputs that gives a driver what s/he needs to know to make the best driving decisions.  I also agree that not everyone computes those inputs equally or reacts with speed and acuity for best results.  Some people are always better than others at similar challenges.  Thanks... Terry

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #86 on: July 31, 2019, 11:39:00 PM »
As I had it put during an on-track bike school:

Look down the road/course at where you're going.  It's too late to do anything about where you are right now - you should have seen it coming while you were looking ahead.

My point exactly Slim.  Where we'll be in the next instant ahead depends on how we reacted to whatever sensory input that was available in the last instant past.  How we position ourselves to receive and subsequently interpret inputs as they arrive, and the fidelity of those inputs on a corresponding value scale, forms the entire basis of our coordinated response.  Too little or inaccurate info and we are likely to make bad decisions. Rejecting good info because we're either unwilling to accept or ill informed about it's usefulness can also lead to bad decisions.  Examining our input options equally and fairly offers the best chance that the inputs we need in any give operating scenario will be there when we need them for the best decisions we as individuals are capable of making. Thanks... Terry
« Last Edit: July 31, 2019, 11:48:48 PM by Simspeed »

Offline RidgeRunner

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Re: Simspeed UWD LSR Design Project
« Reply #87 on: August 01, 2019, 07:04:54 AM »
I'll spare everyone else the bother and tell you that's John Cobb sitting in the Railton Special, later the Railton Mobil Special.

Cobb held the unlimited LSR, briefly, in September 1938 at 353 MPH, then again between August 1939 and September 1947 at 369 MPH.  In September 1947 Cobb raised the record to 394, including one run at 403.  Breedlove, Donald Campbell, and the Summers Brothers went faster, using different means of propulsion, in 1963, 1964, and 1965, respectively.

Thanks for the interesting thread!

Thank you TD for this info.  I've read through the coverage and videos of Cobb and Campbell's LSR efforts and I'm frankly amazed at the speeds they achieved given the technology of their time.  Both their cars use a DIF layout without a stabilizer fin and didn't seem to suffer from a lack of control until Campbell's 350 mph crash due to what he described as soft salt conditions.  Addition of a fin to the Bluebird rebuild helped him to capture a record two years later.  Any ideas why the DIF of these two cars didn't appear to affect driver control?  Thank... Terry

     I have followed LSR since the late 50's and finally getting to experience being there in '71 & '72,  then again in '08.  From my actual observations, seeing pictures and reading about conditions before and since, I'll say that the  salt surface conditions have changed DRASTICALLY since the time of Cobb's, Campbell's, Breedloves's, Summer's runs and those of others back then.  Current conditions should be a MAJOR factor in any present attempt equations.

    I've found this a very interesting project to follow, stay with it and all my best for your success!

                    Ed

     
« Last Edit: August 01, 2019, 07:09:16 AM by RidgeRunner »

Offline TD

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Re: Simspeed UWD LSR Design Project
« Reply #88 on: August 01, 2019, 07:27:51 AM »
Quote

Thank you TD for this info.  I've read through the coverage and videos of Cobb and Campbell's LSR efforts and I'm frankly amazed at the speeds they achieved given the technology of their time.  Both their cars use a DIF layout without a stabilizer fin and didn't seem to suffer from a lack of control until Campbell's 350 mph crash due to what he described as soft salt conditions.  Addition of a fin to the Bluebird rebuild helped him to capture a record two years later.  Any ideas why the DIF of these two cars didn't appear to affect driver control?

No idea really.  Both cars featured relatively wide track and all-wheel drive, which might have made them somewhat easier to drive.

Offline Interested Observer

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Re: Simspeed UWD LSR Design Project
« Reply #89 on: August 01, 2019, 07:55:33 AM »
The potential problem I am describing has nothing to do with suspension travel or side-to-side movement at the Heims.  It has to do with the limited resistance to rotation about the axis between the upper and lower Heims at the narrow ends of the A-arms.  Given mechanical clearances and elasticity, the narrow spacing of the upper Heim pair cannot be considered a rigid connection in a steering rotation sense, but rather just an upper pivot point.  The front wheel assembly is effectively mounted on a kingpin with dubious steering rotation stiffness.