Author Topic: Simspeed UWD LSR Design Project  (Read 13416 times)

0 Members and 1 Guest are viewing this topic.

Offline jl222

  • Hero Member
  • *****
  • Posts: 2719
  • Location: Clovis calif.
Re: Simspeed UWD LSR Design Project
« Reply #195 on: September 20, 2019, 01:38:17 PM »
 
 Carl Heaps push truck? :-D

             JL222
« Last Edit: September 20, 2019, 01:42:45 PM by jl222 »

Offline Seldom Seen Slim

  • Nancy and me and the pit bike
  • Administrator
  • Hero Member
  • ***
  • Posts: 12463
  • Age: 71
  • Location: Skandia, Michigan
  • Nancy -- 201.913 mph record on a production ZX15!
    • Nancy and Jon's personal website.
Re: Simspeed UWD LSR Design Project
« Reply #196 on: September 20, 2019, 01:51:58 PM »
" Carl Heaps push truck? :-D"

HahahaHaha!  Good one, Mr. Langlo, sir!
Jon E. Wennerberg
 a/k/a Seldom Seen Slim
 Skandia, Michigan
 (that's way up north)
2 Club member x2
Owner of landracing.com

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #197 on: September 20, 2019, 04:11:52 PM »
Terry,
How are you deriving your Cd, Cp, Yaw rate etc and other aero numbers?
Hi Bratfink,
At this stage all I can do is compare the current body geometry to Cd, Cp, frontal area, weight, and hp of existing liners where the information is published. The Buckeye Bullet 3 and the JCB DieselMax liners both published that information based on CFD analysis, dyno results, and physical data.

The BB3 has a Cd of .09 and frontal area of 7.5 sq.ft. I think it was, and weight of 9000 lbs with 2 mW power (2682 hp).  The JCB liner has a Cd of .14 and 12.4 sq.ft. frontal area @ 5800 lbs with 1500 hp.  Those numbers may not be exact I'm recalling them from memory.  Both cars went 350 mph. 

What I find interesting is the reported hp numbers for both cars.  The JCB effort @ 1500 hp is way lower than 2413 hp my formulas say is needed for 350 mph.   The BB3 car on the other hand shows a need of 3484 hp using my formula primarily due to the added weight which factors into the Cr.

Assuming same .09 Cd for the SSpeed body geometry (from appearances I believe the SSpeed geometry is better than the BB3 number) the known 4 sq.ft. frontal area, and a revised weight of 3000 lbs (or less) due to new construction using CF tubing, CF plate, and 3D printed titanium tubing connectors (see drawing below) my formula shows a need of 1195 hp for 350 mph.  If we say my formulas overstate the needed hp (given that both the JCB and BB3 cars hit that speed with less hp than my formulas show) then 38% and 23% less hp respectively for the JCB and BB3 cars would equate to and average of 30% less or 836 hp needed for the SSpeed design @ 350 mph; or 1639 hp @ 600 mph.  My formulas now show a need of 2342 hp @600 mph based on the new 3000 lb weight.  At the old 4500 lb weight the hp needed was 3291.  This is all speculation of course but for now that's all I have to go on.

If you or anyone has known Cd, Cp, FA, weight and hp values for other record setting efforts please share them so I can plug them into the formulas in an attempt to make whatever corrections are needed.  Thanks... Terry.

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #198 on: September 20, 2019, 04:28:06 PM »
Quote
Terry: We could use a center swivel for the trailing wheel much like the tail wheel of a tail dragger airplane.  It would then be easy enough to add sprung suspension for that trailing wheel

Simple test to delete that idea is to look at supermarkets' trolley wheels whizzing about from side to side with no coordination whatsoever while irate pusher is attempting to push in a straight line!!!

Also, push start to 150mph... You'll then need another LSR car with a gear box (and probably more power than your LSR car) to start this LSR car???

Why not simplify this drastically and transfer the engine and gear box from this LSR pusher to that LSR car?

Patrick

Hi Patrick,
Yes I agree, rear single point pushing anything with a free pivoting real wheel won't work.  But as they say there's more than one way to skin a cat.  The pivoting trailing wheel is just another idea that may or may not be feasible.  I'm looking to you guys to help keep my ideas from drifting too far afield. 

I don't see a problem however with gearing a high hp turbo diesel dually push vehicle to hit 150 mph in 1/2 mile or so pushing a 3000 lb vehicle.  In slop it won't happen but on hard salt it could.  Those are the only conditions an unlimited attempt like this should take place anyway.  The current SSpeed design doesn't use a transmission for space limitations.  But that's not to say we can't configure a different powertrain design w/transmission that still uses the same body geometry.  The whole point of this exercise is to arrive at a feasible design with the lowest Cd, FA, and weight possible to set an unlimited WD record. Thanks... Terry.

Offline Stan Back

  • Hero Member
  • *****
  • Posts: 5115
  • Location: San Berdoo
Re: Simspeed UWD LSR Design Project
« Reply #199 on: September 20, 2019, 05:22:24 PM »
Using push vehicles is, of course, allowed because of the high gearing of the race vehicles, in addition to not plastering the starting line members with salt and/or dirt.

I'd sure guess the the SCTA would require full race vehicle specifications for such a push truck and its driver in the case you're putting together.
Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club".
Celebrating 67th anniversary of racing on the salt.

Offline tortoise

  • Sr. Member
  • ****
  • Posts: 597
  • Age: 77
  • Location: Sequim, WA
Re: Simspeed UWD LSR Design Project
« Reply #200 on: September 20, 2019, 05:28:11 PM »
  In slop it won't happen but on hard salt it could.  Those are the only conditions an unlimited attempt like this should take place anyway.
Or any 300+ attempt, as recently, disastrously, demonstrated.




Offline RichFox

  • Hero Member
  • *****
  • Posts: 2605
  • Location: San Mateo, Ca
Re: Simspeed UWD LSR Design Project
« Reply #201 on: September 20, 2019, 05:52:46 PM »
fastest diesel pickup I see is 227 mph I guess in the last (5th) mile. 150 in the first half mile means he only picked up 75 mph in the remaining 3 1/2 miles. And he wasn't push starting anything. Especially some long very low and hard to see car. With a driver also having a hard time due to the lack of reference points to help him stay straight. I don't know how much experience you have had pushing off at a high , but much less than 150,  speed. It's not that easy. I would not accept a job pushing a 'liner at 150

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #202 on: September 20, 2019, 06:11:26 PM »
I'd say we'd need a push truck with gearing and torque to hit 150 max speed by the 1/2 mile mark.

The benefit of pushing to 150 by the 1/2 is the removal of any need for brakes or parachutes on the car since the resulting crash will slide/tumble to a stop around the one.

This also has the added benefit of allowing the safety equipment to be pre-staged there since the final location of the accident debris is pretty much a given.
Quote
Have you ever driven a pushee at 150 mph. A bit on the difficult scale.
DW
Quote
So all you need is a push truck that will go 150 while push starting your liner in 1/2 mile? On salt? Sounds like you need to start a new build diary. This is going to be a pretty fast pickup.

Hi All...
Good points with valid concerns, thanks for the thought provoking comments.  I agree that conventionally pushing a design like this to high speed is troublesome to say the least.  But there's not much about this design effort that's conventional is there?  So let me comment for a bit about why I think this current design is desirable over previous versions and then address the push vehicle.

Let's consider existing conditions that must be overcome for successful results.  Based on what I've read from you traction is the #1 limiting factor for record speeds.  Aerodynamic is #2, stability #3 (due in large part to limited traction), and available hp last. Please tell me if that's wrong, needs reordering or additional items...

#1: Traction is not a problem here because of low torque and 1:1 gearing.  I've eliminated the active aero flap for V.5.8 because of the change in torque characteristics over the previous 100% torque electric motor drive.  When the IC engines light up at 2200 rpm the power curve up to max rpm should be progressively strong depending on port and ignition timing, total weight, and applied power adders.  Based on IO's input I recognized that weight will be an extremely important issue in how the car performs given the new IC direct drive powertrain. 

So, I research to find the best way to affordably apply Carbon Fiber (CF) into the chassis build.  2" x .085 wall high modulus CF square tubing, bonded 3D printed titanium connectors, and bolted/bonded 1/2" multi-directional layered CF plate can be applied to form a super strong/stiff light weight space frame truss chassis.  I'll probably use the same construction technique for the drivers tub instead of the molded design as currently shown.  It's easier to build and cost less overall. 

#2:  Aerodynamically I think the current design at 4 sq.ft FA and low Cd shape is competitive compared to others I've been able to study. 

#3: Stability wise moving away from rear wheel drive to forward drive should greatly help deal with yaw problems that plague more conventional designs, especially since the current plan is to use the DF chassis layout.  The reported stability of the Salt Shark FWD car convinced me forward drive is the way to go if enough traction can be found to eliminate rear drive wheels. We may even reduced the number of drive wheels from 6 back to two using a stacked inline rotor configuration with a forward steering differential and no transmission.  We could then experiment with different diff gearing to help tune the power curve given that rotary IC engine(s) are good to 10,000 rpm max.  That would also eliminate the mechanically disconnected IC powerplants as seen in V.5.8.

#4: Push Vehicle.  Pushing this design from the rear would effectively amount to rear steering from 0 to 150 mph.  I assume everyone agrees that's the wrong approach to take.  However, given a safe alternative I would argue that push starting to somewhere in that speed range to take advantage of the direct drive platform for potential max speed is very desirable.  So here's one alternative that I believe could be safely applied.

If one were to pull this design from the front rather than push from the rear it would be inherently stable up to and beyond LSR applied power.  Knowing that we can't use a tow vehicle to start we need a new design push truck that accomplished the same result from the rear.  A conventional pick up truck isn't the best approach IMO.  We need a custrom built, horse shoe shaped vehicle that surrounds the LSR car from the rear leaving the front open for the LSR to pull away under its own power at the right rpm.

Each leg of the push "shoe" running either side of the LSR would make a "push" connection to the LSR through forward mounted booms that connect with the LSR at nose contact points on each side that effectively "push" the LSR forward up to speed.  Either upon push shoe braking or LSR power, or both, the LSR would pull way and make its run.  The push shoe would then steer off track conventionally and head to the other end.

Effectively, the push shoe truck could also act as a powered exoskeleton trailer that lifts the LSR off the track for maneuvering around the pits and turn around at the end of the track after each run.  Run a sprung dually real axle mated to a turbo diesel or even better a high torque electric motor geared to max out at the 1/2 mile marker.  Use sprung wheels at the nose of each shoe leg for steering with the shoe driver sitting wherever best serves his purpose and control of the vehicle.  Use of a light space frame with roll cage protection for the shoe driver should produce total weight of the two vehicles less than a big dually pick up truck alone.  It should be narrow enough to trailer to the race for use.  Your thoughts please.  Thanks... Terry.



« Last Edit: September 20, 2019, 06:18:54 PM by Simspeed »

Offline kiwi belly tank

  • Hero Member
  • *****
  • Posts: 2607
  • Age: 168
  • Location: Lava Hot Springs Idaho
Re: Simspeed UWD LSR Design Project
« Reply #203 on: September 20, 2019, 06:22:12 PM »
I doubt anybody would let a push go that fast any more. I pushed one of Jim Feuling's cars beyond 100 mph back in the 90's & that was some spooky $hit! Vesco were pushing their liner back in those days with a blown BBC Jeep to get the twin Offy's on boost. That was some interesting crap to watch too!
My new liner is geared for 500+ & will drive away from the line unassisted.
  Sid.

Offline Sumner

  • Global Moderator
  • Hero Member
  • ***
  • Posts: 4065
  • 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 #204 on: September 20, 2019, 06:46:42 PM »
....or 836 hp needed for the SSpeed design @ 350 mph; or 1639 hp @ 600 mph.

Under the common convention that it takes 8 times the HP to double the speed I think that 836 hp to run 350 would result in it taking 4212 HP to run 600. 

If you look at Tubinator's run...

https://www.youtube.com/watch?v=BdBahNZOg9o

they are running 182 at the 1/2 mile and ran an exit speed of 503.  I'd think to run 600 you'd have to be running faster than 150 at the 1/2 mile even on say a 6 mile course.  Over 300+ it is really a drag race unless you have basically a very long course.

As mentioned by you and others to have a chance to run 400+ you need almost a perfect race course/surface.  Given that I think trying to put suspension in the car is not require.  My personal feeling is that much over 250 a suspension can't begin to react to the course conditions in a matter that will make much of a difference.   The car is just going to fast for the suspension to be able to keep up with the conditions.  By the time it reacts to one condition it probably has already experience a number of others.

I'm still not comfortable with the safety of putting the driver out in front of all the wheels.  The driver will react to the feeling in his butt way faster than visually looking at some string in front of him.  I was on bad washboard gravel recently and even at 50 mph was making adjustments by that feel way before I'd be able to looking out the windshield at a piece of string.  Again go out and try it on a gravel washboard road or a snowy one and see if you are correcting by feel or sight.  With a  driver position out front you are putting the driver in a dangerous situation in my opinion.  It is hard enough when the driver is just behind the front wheels and putting him/her ahead of the front wheels just makes it all that more difficult. 

Looking at the video ....

https://www.youtube.com/watch?v=-uNRHo7XH6c

... you can see how much the Turbinator is moving around on the course and how much Dave Spangler has to drive the car.  He is looking out front but I can take a good guess he is driving by what he is feeling more than anything.  Unbelievable driving skills.  I think few people really appreciate what it takes to drive a car fast on the salt.  To help keep them safe give them all the help they can get.

Sumner
« Last Edit: September 20, 2019, 06:54:46 PM by Sumner »

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #205 on: September 20, 2019, 07:11:35 PM »
I doubt anybody would let a push go that fast any more. I pushed one of Jim Feuling's cars beyond 100 mph back in the 90's & that was some spooky $hit! Vesco were pushing their liner back in those days with a blown BBC Jeep to get the twin Offy's on boost. That was some interesting crap to watch too!
My new liner is geared for 500+ & will drive away from the line unassisted.
  Sid.
Hi Sid,
I'm just speculating about 150 mph being the needed push speed based on wheel rpm @ 1:1 direct drive.  Using a steering diff, final drive gearing could be changed to take advantage of the rotor engine's max top speed of 10,000+ rpm allowing a lesser push speed to hit the take off rpm.  Going to a slightly smaller 23" wheel from 23.5 would help too. Thanks... Terry

Offline Stan Back

  • Hero Member
  • *****
  • Posts: 5115
  • Location: San Berdoo
Re: Simspeed UWD LSR Design Project
« Reply #206 on: September 20, 2019, 07:19:54 PM »
This is starting to remind of, long, long ago, a thread where the author spent day after day trying to name the swoosch that he called a car.
Member of the San Berdoo Roadsters -- "California's Most-Exclusive Roadster Club".
Celebrating 67th anniversary of racing on the salt.

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #207 on: September 20, 2019, 07:26:05 PM »
....or 836 hp needed for the SSpeed design @ 350 mph; or 1639 hp @ 600 mph.

Under the common convention that it takes 8 times the HP to double the speed I think that 836 hp to run 350 would result in it taking 4212 HP to run 600. 

If you look at Tubinator's run...

https://www.youtube.com/watch?v=BdBahNZOg9o

they are running 182 at the 1/2 mile and ran an exit speed of 503.  I'd think to run 600 you'd have to be running faster than 150 at the 1/2 mile even on say a 6 mile course.  Over 300+ it is really a drag race unless you have basically a very long course.

As mentioned by you and others to have a chance to run 400+ you need almost a perfect race course/surface.  Given that I think trying to put suspension in the car is not require.  My personal feeling is that much over 250 a suspension can't begin to react to the course conditions in a matter that will make much of a difference.   The car is just going to fast for the suspension to be able to keep up with the conditions.  By the time it reacts to one condition it probably has already experience a number of others.

I'm still not comfortable with the safety of putting the driver out in front of all the wheels.  The driver will react to the feeling in his butt way faster than visually looking at some string in front of him.  I was on bad washboard gravel recently and even at 50 mph was making adjustments by that feel way before I'd be able to looking out the windshield at a piece of string.  Again go out and try it on a gravel washboard road or a snowy one and see if you are correcting by feel or sight.  With a  driver position out front you are putting the driver in a dangerous situation in my opinion.  It is hard enough when the driver is just behind the front wheels and putting him/her ahead of the front wheels just makes it all that more difficult. 

Looking at the video ....

https://www.youtube.com/watch?v=-uNRHo7XH6c

... you can see how much the Turbinator is moving around on the course and how much Dave Spangler has to drive the car.  He is looking out front but I can take a good guess he is driving by what he is feeling more than anything.  Unbelievable driving skills.  I think few people really appreciate what it takes to drive a car fast on the salt.  To help keep them safe give them all the help they can get.

Sumner
Hi Sumner,
I agree the 1639 hp is a bogus number.  As is the 836 in my opinion.  Very hard to estimate needed hp based on available info for aero and rolling drag formulas.  Hardly anything correlates between published info of other cars as well.  I do believe it took more than 1500 hp for the JCB car to hit 350.  2600 for the BB3 car seems more in line with their 350 record with better aero but greater weight.  Going back to 8 rotors, I think 4000 hp is the max limit for the SSpeed design study.

I'm now counting on fwd as seen in the Salt Shark to make the DF position viable for this design.  He sits ahead of the drive/steering wheels in the DF position and said the SS car was rock stable even on the bad track in August.  His and everyone else's slower speeds reflect how difficult it was to gain traction at that event.

Does anyone have info about other fwd cars (any class) and their driveability on the salt?  Thanks... Terry

Offline Simspeed

  • Sr. Member
  • ****
  • Posts: 300
  • Age: 67
  • Location: Black Hawk, Colorado
Re: Simspeed UWD LSR Design Project
« Reply #208 on: September 20, 2019, 07:27:42 PM »
This is starting to remind of, long, long ago, a thread where the author spent day after day trying to name the swoosch that he called a car.
Hi Stan,
I did a search for "swoosch" and found nothing... tell me more about it?  Thanks... Terry

Offline tortoise

  • Sr. Member
  • ****
  • Posts: 597
  • Age: 77
  • Location: Sequim, WA
Re: Simspeed UWD LSR Design Project
« Reply #209 on: September 20, 2019, 07:44:03 PM »
Under the common convention that it takes 8 times the HP to double the speed I think that 836 hp to run 350 would result in it taking 4212 HP to run 600.
That "common convention" is HP to overcome aero drag, with the assumption that rolling resistance is relatively negligible at high speeds. Simspeed's model, if I recall, shows rolling resistance as a much larger component of overall drag. (Correct me if I'm wrong, Simspeed.)  I think he needs to defend that model, if he's basing his design upon it.