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The Heterodox GT-R LM Nismo Endurance Racer


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#1 desmo

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Posted 13 February 2015 - 00:13

This car is cool, at least I think it is.  So cool in fact that it deserves better than to be folded into a broader thread.  And it's already working, already winning, already bringing more good attention from outside to motorsport than a whole grid full of cookie cutter F1 cars only a small handful the most devoted anoraks could reliably identify minus their liveries. As proof I offer this article from Wired--which I found myself at times actually nodding in agreement with.  And I never find much if anything to agree with in most motorsport coverage outside the specialty press.

 

http://www.wired.com...d-dose-insanity



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#2 Kelpiecross

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Posted 13 February 2015 - 04:26

I suspect the car will be quite successful.    It should have at least some of the typical FWD stability and controllability that most small FWD sedans have.

 

  But - Christ it's ugly.      

 

 My "quote" function has stopped working - is there a cure for this problem?    



#3 BRG

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Posted 13 February 2015 - 20:06

And it's .... already winning, 

 

It is?? :confused:



#4 Greg Locock

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Posted 13 February 2015 - 23:05

One feature puzzles me. The extension of the front wheel spats aft looks like a recipe for yaw instability. Or is it that they have enough yaw stability and are merely going for balance-otherwise in a crosswind you have to fight the weathercocking? Other than that, in an aero dominated race it looks like a cunning rethink.


Edited by Greg Locock, 13 February 2015 - 23:07.


#5 Magoo

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Posted 13 February 2015 - 23:26

This car is cool, at least I think it is.  So cool in fact that it deserves better than to be folded into a broader thread.  And it's already working, already winning, already bringing more good attention from outside to motorsport than a whole grid full of cookie cutter F1 cars only a small handful the most devoted anoraks could reliably identify minus their liveries. As proof I offer this article from Wired--which I found myself at times actually nodding in agreement with.  And I never find much if anything to agree with in most motorsport coverage outside the specialty press.

 

http://www.wired.com...d-dose-insanity

 

I am just starting to study the car, but to me it's about the most interesting thing to happen in race cars in years. 



#6 BlinkyMcSquinty

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Posted 14 February 2015 - 02:39

One feature puzzles me. The extension of the front wheel spats aft looks like a recipe for yaw instability. Or is it that they have enough yaw stability and are merely going for balance-otherwise in a crosswind you have to fight the weathercocking? Other than that, in an aero dominated race it looks like a cunning rethink.

That is a good point, but I believe Nissan has made sure the center of aerodynamic pressure from the side is well aft. That cockpit is very far back, and it also has the huge fin running from the top of the cockpit all the way back.

 

The car appears to be very clean in relation to drag, no surprise when it is obvious it is built to go very fast. Those clean lines in pursuit of a low drag may have compromised the yaw stability a bit, but IMO it is under control. It also helps to have those monster tires up front, also resisting side forces.



#7 gruntguru

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Posted 14 February 2015 - 05:44

Front engine FWD -> CG will be well forward too.



#8 Wuzak

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Posted 14 February 2015 - 07:13

1000hp through the front wheels. Any problems there?



#9 gruntguru

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Posted 14 February 2015 - 09:15

Not easy, thats for sure. Tyre wear is usually a problem when a race car steers and drives through the same wheels. Torque vectoring helps a lot though and no doubt that will be included.

 

They were leaving-open the option to send recovered energy to the rear wheels. Any news on that?



#10 Greg Locock

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Posted 14 February 2015 - 10:34

1000hp through the front wheels. Any problems there?

In an endurance race? perhaps somebody could post an image of whp vs distance for a typical lap.



#11 BlinkyMcSquinty

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Posted 14 February 2015 - 12:57

1000hp through the front wheels. Any problems there?

It is not just one lump sum through the front wheels. The ICE contributes 500 HP and the flybrid 750. IMO during initial cornering and until the car reaches over 120 kph, the ICE will be pulling the front wheels and the flybrid will contribute some through the rear end. But once going in a relatively straight line and when the downforce is sufficient to really plant the front tires, then all the power will be directed through the front wheels and then we will see a WEC version of a top fuel dragster.

 

I am firmly convinced that this car has a lot more front downforce than a casual glance will imply. A great amount of design priority is allocated to making the front diffuser extremely efficient. Locating the engine and gearbox in front of the driver, all those long ducts from front to rear, the crazy path the rear drivertrain has to take, all this is done so that the front diffuser is efficient. So once the car is up to speed, that front end is going to be planted. Even in very fast corners I expect the Nissan to be able to hold it's own.



#12 BRG

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Posted 14 February 2015 - 17:04

I am struggling to think of any FWD road or competition car with more than about 300bhp.  Why do Nissan think they can put down 550+ bhp?  It seems a recipe for poor handling, difficult cornering, broken CV joints and high tyre wear.



#13 thegforcemaybewithyou

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Posted 14 February 2015 - 17:27

The weigth distribution is extremely forward, Nissan claims 65% front and 35% rear. So even during high accelerations, the front tyres should be loaded high enough. And traction control is allowed in WEC, that should also help with stability and tyre wear and make it easier to control these high power outputs.

 

The "double diffuser" in theory also shifts the aerodynamic distribution more to the front. I'll be interesting to see the first laptimes at Le Mans.



#14 Greg Locock

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Posted 14 February 2015 - 21:35

if the cg were at ground level then there would be no particular difference between fwd and rwd, except for steering. So another of their design goals may have been to get a very low cgz/wheelbase, and by putting the engine at the front that may be easier, as it is no longer above (or in) the diffuser.



#15 desmo

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Posted 14 February 2015 - 22:12

It is?? :confused:


Yes. Racing is first and foremost a marketing and branding exercise.

#16 desmo

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Posted 14 February 2015 - 22:16

I suspect the car will be quite successful.    It should have at least some of the typical FWD stability and controllability that most small FWD sedans have.
 
  But - Christ it's ugly.      
 
 My "quote" function has stopped working - is there a cure for this problem?


I think you can just manually type in quote tags if the javascript to insert them is acting up in your browser. Let's see-

Test


Yep.

#17 Wuzak

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Posted 15 February 2015 - 00:03

My "quote" function has stopped working - is there a cure for this problem?

 
Which quote button?
 
The one at the bottom of posts?

16530392571_5b55a3d1e0_z.jpg

Or the one in the reply window?

16344650990_437bb83860_z.jpg

If it is the later, you may have this switch on.

16346198827_1ac0fc4f6a_z.jpg

All the other options are unaccessable. 

 

Just switch that off and the other buttons should work.

 

 

But as Desmo says, you can still manually write the tags in if this is not the problem.


Edited by Wuzak, 15 February 2015 - 00:04.


#18 Catalina Park

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Posted 15 February 2015 - 00:31

It is pointless discussing the merits of this car until Lee has given his views.



#19 imaginesix

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Posted 15 February 2015 - 01:42

The underbody must be a treat to look at. I image a perfectly shaped inverted wing profile, so massive low speed downforce and little drag.

 

What's the slowest corner at Le Mans? 100 km/h?



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#20 Wuzak

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Posted 15 February 2015 - 02:50

Is the Nissan going to run at other WEC besides Le Mans?



#21 Kelpiecross

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Posted 15 February 2015 - 04:16

Is the Nissan going to run at other WEC besides Le Mans?


Thank you Woozy and Des - now it works. My problem was with the "quote" at the bottom of the post. I clicked on the first option in the reply window and now it works - I have no idea why.

#22 Lee Nicolle

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Posted 15 February 2015 - 09:52

It is pointless discussing the merits of this car until Lee has given his views.

Its butt ugly. I can see some facets of the Cube in design!

I dont want one.



#23 BRG

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Posted 15 February 2015 - 19:15

Yes. Racing is first and foremost a marketing and branding exercise.

So you consider that Nissan sales have increased already due to this car?  I doubt the typical Nissan buyer has even registered that the LMP car exists.  If it wins Le Mans, then maybe.



#24 desmo

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Posted 15 February 2015 - 21:04

Obviously not, that's a strawman.  But it's got a headstart before it's even turned a wheel in anger against every other LM entrant in critical branding and marketing.  When was the last top tier LM prototype that anyone outside of motorsport was paying the least attention to? I'll even include LM winners. When it proves competitive, the buzz will get loud.



#25 BRG

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Posted 15 February 2015 - 21:51

Hmm, so its already winning (the marketing war) but there is no benefit from the victory?  Perhaps you were just a tad over-effusive in the OP.  Something that this car seems to encourage for some reason.



#26 desmo

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Posted 15 February 2015 - 21:55

I said there was no benefit for a victory?  :lol:  Of course winning is additive.  You're going to sprain something building those strawmen and carting them out



#27 BRG

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Posted 15 February 2015 - 21:58

"When was the last top tier LM prototype that anyone outside of motorsport was paying the least attention to?"   :wave: 



#28 desmo

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Posted 15 February 2015 - 22:21

It's been awhile.  In the US, the Le Mans battles between Ford and Porsche in the late sixties got a LOT of press including live network broadcast time back when there were only three or four channels and there was pretty widespread astonishment about the 917 when it became competitive.  Since then?  Not sure.



#29 gruntguru

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Posted 15 February 2015 - 22:49

There was a failrly high degree of awareness outside motorsport circles when diesels started making a showing.



#30 desmo

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Posted 15 February 2015 - 22:54

I almost brought that up but the degree of obvious visual distinction wasn't in the same class as the Nismo car--or even a longtail 917 done up in psychedelic paint.



#31 chunder27

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Posted 16 February 2015 - 23:42

NHRA tried to push fwd drag cars a few years ago, it is entirely possible.

 

FWD drag racing is massively popular in some areas of the US and other parts of the world. I know a lot of you will think drag racing a poor example, but think of the issues?

 

You have to apply that poiwer through a fairly conventional tranny, using a diff and driveshafts that are steering too,

 

You have no advantage in weight really other than having a reverse situaiton to say a Beetle in that the engine is over the wheels, a fwd drag car has nothing in it behind the driver.

 

Torque steer, can yu imagine it? 

 

The works Chevy Cobalt fwd Pro drag car had 1600hp, it was a bit of a cheat becaise the engine was Audi like, right up front, longitudinal, with a direct drive box behind it so the fwd was still within the silhouette, but it was fwd, it steered the front wheels.

 

Not a similar comparison I know but you get hte point, high power can work in fwd cars.

 

And the numbers?  This thing was capable of just under 7 second quarter miles.



#32 tcsparky

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Posted 17 February 2015 - 19:45

I wonder if any thought was given to rear steering? Probably make it hard to pass in a turn. But no torque steer influence.



#33 kikiturbo2

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Posted 18 February 2015 - 09:15

I wonder if any thought was given to rear steering? Probably make it hard to pass in a turn. But no torque steer influence.

 

we had a discussion on this a while ago and conclusion was that is was a no go..



#34 Greg Locock

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Posted 18 February 2015 - 10:24

Torque steer is solvable by many means, perhaps the simplest is to remove all feedback through the steering wheel, but there are mechanical solutions like the revo knuckle. Even the crudest fix would be better than rear end steering.



#35 kikiturbo2

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Posted 18 February 2015 - 10:44

Frankly speaking, I think that on a modern smoooth race track, torque steer and steering feel are of very low importance..



#36 chunder27

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Posted 18 February 2015 - 10:51

I think I would speak to Sir Richard Noble before employing any kind of rear wheel steering setup.

What those guys do not know about stresses and dynamics of that kind of deal, no-one on earth will!



#37 Greg Locock

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Posted 18 February 2015 - 22:20

I don't think I'd bother. Try plotting the lateral force on the steered rear axle as it enters a turn, then apply a mid turn correction, and then straighten up again. No need to phone a friend.



#38 BRG

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Posted 18 February 2015 - 23:14

Any experienced forklift truck driver could help out?



#39 Greg Locock

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Posted 19 February 2015 - 06:55

Yeah that Andy Green, dead wiz on a forklift.

 

I suppose mine was a rhetorical question, but if we imagine entering a left hand turn, first we have to apply a rightwards force to the rear axle, then the front axle builds up a leftwards force, and eventually the rear axle does the same, passing through zero on the way, and then if we make a mid course correction the first thing we have to do is accelerate the rear axle the wrong way, and then the front axle builds up a force the right way, and eventually the rear axle passes through zero and starts to accelerate the right way, and so on for the exit. If that sounds better than torque steer, go for it. Many years of experiments suggest that steering the front axle works better.



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#40 kikiturbo2

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Posted 19 February 2015 - 11:48

Also, with rear steer the slip angle on front wheels, which you need to create sideways force, becomes the slip angle of the whole chassis.. :)



#41 DaveW

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Posted 19 February 2015 - 21:06

Most modern aircraft have a tricycle undercarrage with a steered nosewheel.  There is a good reason for that, as a simple model can demonstrate.



#42 gruntguru

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Posted 19 February 2015 - 22:41

Yeah but - what about forklifts? :)



#43 NeilR

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Posted 20 February 2015 - 01:45

and a treadmill to see if it will take off...



#44 bigleagueslider

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Posted 20 February 2015 - 06:24

Most modern aircraft have a tricycle undercarrage with a steered nosewheel.  There is a good reason for that, as a simple model can demonstrate.

The landing gear used on large commercial jets is not really a tricycle configuration. A 737 uses two MLG with 4 wheels on each unsteered bogie and a single NLG with two steered wheels. That's a total of 10 wheels and 5 axels.



#45 gruntguru

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Posted 20 February 2015 - 08:00

Oh, they're tail-draggers then. :)



#46 DaveW

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Posted 20 February 2015 - 08:05

The landing gear used on large commercial jets is not really a tricycle configuration. A 737 uses two MLG with 4 wheels on each unsteered bogie and a single NLG with two steered wheels. That's a total of 10 wheels and 5 axels.

... and the 777 has a steered axle on each mainwheel bogie.  Nevertherless, the principal applies, I think.

 

A "taildragger" undercarriage layout is unstable (you might look up "ground loops"), as I believe Andy Green discovered in "ThrustSSC".  Bloodhound seems to have corrected this, along with a few other issues.


Edited by DaveW, 20 February 2015 - 08:11.


#47 Fat Boy

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Posted 20 February 2015 - 17:19

I would venture to guess that commercial jets don't tend to spend much time at high tire slip angles or max.lat. G on the ground. I think it's a fair guess you might have different steering geometry design bogies on an airliner (or forklift) than a race car.



#48 DaveW

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Posted 20 February 2015 - 22:30

I would venture to guess that commercial jets don't tend to spend much time at high tire slip angles or max.lat. G on the ground. I think it's a fair guess you might have different steering geometry design bogies on an airliner (or forklift) than a race car.

I rather wish I had not interfered.

 

But I was reminded of a lecturer (way back) who introduced the topic of aircraft undercarriage design by launching a simple model fitted with three wheels along a table.  No matter what angle he launched the model, it always ended up with the single wheel pointing forwards.  It is obvious in rectrospect (see here, in the second diagram), but the demonstration remained with me.  Much later I repeated the test to Richard Noble (clearly with no effect).  I was told that Andy Green (brave man) controlled the path of the ThrustSSC by "pulse width" modulating the steer angle.


Edited by DaveW, 20 February 2015 - 22:41.


#49 bigleagueslider

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Posted 22 February 2015 - 02:19

There are numerous landing gear configurations used on large jets. For example, the 747 uses three MLG and a single NLG, the A380 which uses four MLG and a single NLG, and the C5 which uses four MLG and a single NLG with four wheels for a total of 28 wheels.

 

And then there is the B-52, which uses 4 steered MLG:

 

110315-F-QZ836-015.jpg

 

As for slip angle or lateral G large aircraft tires are subject to, consider a 600,000lb 747 touching down at over 100kts with a 20kt cross wind. The aircraft will be yawed quite a bit so the MLG tire initial contact can be at a fairly high slip angle.



#50 Kelpiecross

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Posted 22 February 2015 - 03:33

Around 1950 Goodyear tested landing gear that was castering in its action to reduce forces on the undercarriage in crosswind landings.