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Author Topic: Simspeed UWD LSR Design Project  (Read 17381 times)

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Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #180 on: September 08, 2019, 01:53:02 PM »
The drawings aren't in order due to the size limitations...

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #181 on: September 08, 2019, 01:54:28 PM »
Big file sizes...

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #182 on: September 08, 2019, 01:55:44 PM »
Jumping around so not to exceed the file size restriction...

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #183 on: September 08, 2019, 01:56:34 PM »
Almost there...

Offline manta22

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Re: Simspeed UWD LSR Design Project
« Reply #184 on: September 08, 2019, 03:17:03 PM »
"The power between wheel pairs is not mechanically linked.  We've combined the throttle bodies and intake plenum for the two rotor and three rotor engines so they breath common air and share that control signal.  The two steering wheels have separate throttle bodies and air boxes so controlling the spark through a single engine controller for all rotors is the sync method to be used in conjunction with calibrated throttle linkage."

I seem to remember that the JCB DieselMAX had a problem of getting their two engines to synchronize properly.

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

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #185 on: September 08, 2019, 05:18:08 PM »
@Terry.  Updates?  Did you make it out to SpeedWeek this year and converse with some of the streamliner guys to further your education?    Inevitably there is a massive amount of knowledge and talent out there on the salt to learn from.  Hopefully you had the chance to take advantage of it.

Just in time for the latest update Super.  :-)  No I didn't get to go to SpeedWeek this year but I'm hoping to do so next year.  For now I'll look to you guys (gals) here to help educate me on the fine art of land speed racing.  Thanks... Terry.

Offline DaveL

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Re: Simspeed UWD LSR Design Project
« Reply #186 on: September 09, 2019, 07:50:04 AM »
Hi Terry,
I've been following this build diary with interest and couldn't help notice the similarity with your latest revision and that of fellow Australian Johnny Conway's 'Mach 1' LSR car from the mid seventies. How are these for specs; 32 rotary engines arranged in pairs directly attached to 16 solid aluminium drive wheels, some pairs fixed and some steered. No clutch or transmissions so push start only. Four more rotary engines driving superchargers for the main drive engines. Even looked vaguely similar to your latest design however he lay prone at the rear and used cctv for forward vision. Predictably it was never finished, hope the same doesn't become of your project.
Cheers, Dave.

Offline Interested Observer

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Re: Simspeed UWD LSR Design Project
« Reply #187 on: September 09, 2019, 08:41:11 AM »
Comments on latest version:
Is power curve compatible with wheel speed and power needed for both acceleration and top end?  Wankels notorious for gutless low end.  If it won?t accelerate from 50 mph, probably won?t get to 500.
Good luck push-starting 7 independent and rotationally uncoordinated IC engines.
With 5 axles, wheel load distribution is all over the place and variable.  Tail wheel detracts from power wheel traction.
Very wobbly chassis in lateral and torsional motion at two-rotor location.
Steering so close to main power wheels gives little leverage or fine control.  Steering will be fighting the tail wheel as well as trying to side-slip the power wheels.
Assuming there is a CV joint of some sort in the steering upright member.  Otherwise kinematically incompatible with suspension movement.  In any case, suspension movement induces lateral movement of the contact patch.  Probably unsettling for driver.
Rear aero yaw ?control? a bad idea.  Also induces roll.
Braking capability appears to be far in excess of what can be put to the ground through one alloy wheel.

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #188 on: September 09, 2019, 11:40:34 AM »
Hi Terry,
I've been following this build diary with interest and couldn't help notice the similarity with your latest revision and that of fellow Australian Johnny Conway's 'Mach 1' LSR car from the mid seventies. How are these for specs; 32 rotary engines arranged in pairs directly attached to 16 solid aluminium drive wheels, some pairs fixed and some steered. No clutch or transmissions so push start only. Four more rotary engines driving superchargers for the main drive engines. Even looked vaguely similar to your latest design however he lay prone at the rear and used cctv for forward vision. Predictably it was never finished, hope the same doesn't become of your project.
Cheers, Dave.

Hi Dave,
Thanks for the lead to Conway's 'Mach 1" LSR car.  I'd never heard of it before so cool to see how someone else approached using rotary power for an LSR car.  Both designs are unique even with the direct driven wheel commonality.  I would love to have seen his design hit the salt.  The likelihood of my design ever seeing the light of day is slim at best but one can hope and pray it will and leave the rest up to God's will.  Thanks... Terry.

Offline Simspeed

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Re: Simspeed UWD LSR Design Project
« Reply #189 on: September 09, 2019, 06:38:14 PM »
Comments on latest version:
Is power curve compatible with wheel speed and power needed for both acceleration and top end?  Wankels notorious for gutless low end.  If it won?t accelerate from 50 mph, probably won?t get to 500.
Good luck push-starting 7 independent and rotationally uncoordinated IC engines.
With 5 axles, wheel load distribution is all over the place and variable.  Tail wheel detracts from power wheel traction.
Very wobbly chassis in lateral and torsional motion at two-rotor location.
Steering so close to main power wheels gives little leverage or fine control.  Steering will be fighting the tail wheel as well as trying to side-slip the power wheels.
Assuming there is a CV joint of some sort in the steering upright member.  Otherwise kinematically incompatible with suspension movement.  In any case, suspension movement induces lateral movement of the contact patch.  Probably unsettling for driver.
Rear aero yaw ?control? a bad idea.  Also induces roll.
Braking capability appears to be far in excess of what can be put to the ground through one alloy wheel.

Hi IO,
Thanks for all the identified issues...exactly what I'm looking for from the forum.  I'll address my thinking on these items as follows:

For clarification, the 7 rotors are combined in the following groupings: (1) three rotor engine; (1) two rotor engine; and (2) one rotor engines for a total of 4 powerplants driving 6 wheels.  The 7th trailing wheel is not powered.

Power curve:  The 23.5 diameter aluminum wheels turn 8582 rpm @ 600 mph (7152 rpm @ 500 mph).  Consequently the direct drive engines turn the same rpm as the wheels for all speeds.  Since salt traction is at a premium, running a low torque powertrain with a lot of contact patch would seem idea if power increases significantly with rpm up to the distance limit. I would imagine the ideal power curve would allow max rpm to hit at the max distance.  The power curve question you posed IO depends on mass, drag, and traction between 0 mph and whatever rpm is achievable by the 5 mile marker. 

I'd say we'd need a push truck with gearing and torque to hit 150 max speed by the 1/2 mile mark. That's 2145 rpm on the engines where I believe the power curve would begin to kick in relative to vehicle mass.  Dropping total weight down between 3000 to 3500 lbs would go a long way toward a desirable acceleration rate.  BTW... what's the push distance limit?

Push starting:  I personally don't see a problem push starting the 4 engines.  With zero slippage, all 6 wheels in contact with the track surface will be turning the same rpm when the ignition is lit. The 3 and 2 rotor engines will each use a common crank/axle so those rotors will be rotational indexed to fire in the proper sequence.  The 2 single rotor engines will run independently but throttle matched to the 2 and 3 rotor engines.  Only when wheel slippage occurs will we see a disparity between engine rpm(s) but common ramp settings across the throttle bodies should compensate to bring that back in line within some acceptable range.  At this time I have no idea what that would be.

Wheel load distribution:  The two steering wheels are sprung so the 3 fixed axles will be most affected by load distribution.  On a perfectly flat surface loads would be balanced relative to Cg for all wheels I believe.  From appearances I think the Cg will be close to the axle centerline of the 3 rotor engine.  Depending on chassis flex effective load on the trailing wheel will be a non-issue traction wise to the forward power wheels.

Wobbly chassis:  I agree with your comment here.  I've included a drawing showing added reinforcements to that section of the chassis.

Steering:  I think there's an advantage here from the two inline steering wheels.  The angular distance between the lead steering wheels and the fixed wheels offers a slight benefit over a single steering wheel or a pair of side spaced wheels.  I've also been told its beneficial to slow the steering way down on these cars over what we might otherwise think it should be, so effectively we're getting that here with this arrangement.

I see your point about the steering wheels fighting the trailing wheel with the fix wheels in between. 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.

CV Joint:  Yes indeed there are CV joints drawn within the steering spindles.  The upper and lower arms that center the spindle hinge in alignment to one another such that there is no camber change throughout the suspension movement. Because the spindle center is aligned with the center of the wheel there is zero scrub angle as well.

Rear Aero Yaw control:   I remember posing this question a while back, thanks for responding.  I have no such controls draw into this design.

Braking Capability:  Yes, I recognized that too so I'd say this is a redundancy rather than a necessity.

Thanks IO... Terry.
« Last Edit: September 09, 2019, 06:43:43 PM by Simspeed »

Offline Bratfink

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Re: Simspeed UWD LSR Design Project
« Reply #190 on: September 19, 2019, 02:19:27 PM »
Terry,

How are you deriving your Cd, Cp, Yaw rate etc and other aero numbers?

Offline thefrenchowl

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Re: Simspeed UWD LSR Design Project
« Reply #191 on: September 20, 2019, 03:45:47 AM »
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
Flat Head Forever

...What exactly are we trying to do here?...

Offline JR529

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Re: Simspeed UWD LSR Design Project
« Reply #192 on: September 20, 2019, 11:07:04 AM »
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.

Offline dw230

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Re: Simspeed UWD LSR Design Project
« Reply #193 on: September 20, 2019, 11:32:04 AM »
Have you ever driven a pushee at 150 mph. A bit on the difficult scale.

DW
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Alcohol - because no good story starts with a salad.

Offline RichFox

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Re: Simspeed UWD LSR Design Project
« Reply #194 on: September 20, 2019, 01:13:14 PM »
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.