Slalom4me

An image I have not seen before. The design of the front clip caught
my attention ...


.

ghoffman

Very interesting structure but I fear that it is technology for technology's sake with no value added. It is still over 3700 lbs with more than 51% front end weight and it is a 2 seat car! It seems that no MB structures engineer could ever get a job at a US aerospace company. A few years ago the F-35 program manager at Lockheed Martin was fired and walked out the door for repeatedly blowing the weight budget.

mgarfias

And it still weighs 29,000lbs empty. Just how is this supposed to replace an 18,000lb fighter? Thing just smacks of being the next F-111.

VetteDrmr

OT, but since the question was asked:

F-16 C/D: empty weight 19,200 lb.
F/A-18 E/F: empty weight 30,500 lb.
AV-8B: empty weight 13,940 lb.
F-35A: 29,000 lb. (F-16 replacement)
F-35B: 32,161 lb. (AV-8B replacement)
F-35C: 32,000 lb. (F/A-18 E/F replacement)

Weight is always a bugaboo, but some things need to be considered on a stealth aircraft. All stores (including external fuel tanks) have to be internally carried. So, the F-35 carries much more fuel internally than the aircraft it's replacing. Put any of the current aircraft into something other than an airshow configuration (usually at least one belly tank) with fuel for the same range, and the weight differential narrows considerably.

A lot of people world-wide are wanting F-35, so I believe the F-35 will succeed where the F-111 was doomed from the start, for many reasons (including weight).

HTH, and have a good one,
Mike

mgarfias

Yes, it needs to carry more internal fuel, which requires a larger airframe. But 10k pounds worth of airframe without fuel?

I'm skeptical of a one-size fits all solution. You end up with an aircraft that does many thing, but none of them well. We'd be better off with light weight fighters that are used to protect a dedicated CAS aircraft, instead of one aircraft that tries to do both.

TLGunman

I guess Mosler should have bragged about the carbon fibre crash absorption structure in the MT900. It passes NHTSA crash reqts in 2004.

varkwso

F-111 weighed in at 50,000 empty...(depends on model)

Doomed from the start my azz....it was a wonderful aircraft for what it was designed for...From Linebacker 2 till the day it was retired (wish they had it back for Afghanistan by the way) it was ideal for its mission.

Having to refiuel your aircraft at the end of the SID is plain dumb....

Slalom4me

With such extensive use of carbon fibre, it is interesting to see the
weight of the SLR, relative to that of the Z06.

I suspect some of the difference lies in the engine: 511.8 lbs for the MB
vs ?? for the LS7. It would also be interesting to see chassis stiffness
values and crash performance results. Perhaps some weight is attributable
to the fact that this is their first effort at building a CF road car?

A comparison of metrics from the SLR and the Z06

.................. SLR ........................ '08 Z06

Weight......: 3,732lbs (DIN) ............ 3,162lbs
Length.......: 183.3" ........................ 174.6"
Wheelbase..: 106.3" ........................ 105.7"
Width.........: 75.1" .......................... 75.9"
Height........: 49.6" ........................... 49.0"
Luggage Cap: 272.0L (VDA) .............. 634.0L
Fuel Capacity: 97.6L ......................... 68.1L

Displacement...........: 5439cc ............ 7008cc
Induction................: Supercharged ... Naturally Aspirated
Cylinder Arrangement: V8 (90º) .......... Ditto

Power....................: 460kW @ 6500 ... 377kW @ 6300
Torque...................: 780Nm @ 3250-5000 rpm ... 637Nm @ 4800

.

VetteDrmr

Count me suitably whacked, my bad, my bad.

I meant that the F-111(C?) that was the Naval variant was doomed from the start. Weight and size were players, but the biggest one of all was politics.

The 'vark was (is) an awesome bird. I actually worked on the upgrade from analog to digital flight controls back in the late 80s, and some of those birds are still flying down under.

Have a good one,
Mike

Slalom4me

Courtesy of Mosler

.

Is there additional significant structure that mounts ahead of the
forward control arm points and front wall of the Mosler's tub?

Courtesy of Rollcentre Racing UK



Here's Tiff of 5th Gear as he pilots an MT900 to best a Ducatti 999



.

TLGunman

Yes. The radiator sits between two crush pillars, comprised of aluminum honeycomb, wrapped in carbon fibre. They do the deceleration of the car, in a front impact.

varkwso

F-111B was the Naval version - it was a vital research platform for the F-14A (~39-42,000 pounds)...I think Iran is the only one flying the F-14 now...


The Aussies are still flying the F-111C and F-111G (reworked FB-111As).

I really liked the digital upgrades by the way

Modern car crush amazingly well to protect the inhabitants!

32valves

isn't this apples vs. oranges?


the mercedes uses a supercharged and intercooled V8 that makes way more power than the LS7. A better comparison would be with the ZR1 where the benz still gives up alot of weight. I imagine mercedes put a alot of content into the car for NVH suppression and comfort that a corvette will not have. The mercedes also uses an auto which adds more weight and is a fair bit larger overall (gotta have that road presence at the price point).

TeddyFreddy

It is sort of apples vs oranges because the target market for the SLR is entirely different.
But that does not change the fact SLR is a failure. Way too heavy, slush-box transmission and no "supercar personality" for huge $$$. Just another big Mercedes. Thankfully is discontinued.

Slalom4me

I had thought about hunting down the ZR1 numbers for the reasons
you mention but ultimately chose the Z06 figures on the basis that
Z06 #'s are easier to find, the SLR/Z06 power-to-weight ratios are
similar and the focus is on the design of the front clip of the SLR
chassis. I am unaware of there being much difference in structure
between the Z06 and ZR1.

I've added some ZR1 numbers below.

.................. SLR ........................ '08 Z06 ................'09 ZR1

Weight......: 3,732lbs (DIN) ............ 3,162lbs ............. 3,350lbs
Length.......: 183.3" ........................ 174.6"
Wheelbase..: 106.3" ........................ 105.7"
Width.........: 75.1" .......................... 75.9"
Height........: 49.6" ........................... 49.0"
Luggage Cap: 272.0L (VDA) .............. 634.0L
Fuel Capacity: 97.6L ......................... 68.1L

Displacement...........: 5439cc ............ 7008cc ........... 6200cc
Induction................: Supercharged ... N-Aspirated ... Supercharged
Cylinder Arrangement: V8 (90º) .......... Ditto ............... Ditto

Power.......: 460kW @ 6500 ............. 377kW @ 6300 .... 462 kW @ ??
Torque......: 780Nm @ 3.2K-5K rpm ... 637Nm @ 4800 .... 823 Nm @ ??

Pwr-Wgt ...: 8.11lb/kW ..................... 8.38lb/kW ........... 7.25lb/kW

Looks like a mismatch in terms of power-to-weight, favouring the ZR1.

382lbs more weight on the part of the SLR. The arguement about wgt
of the automatic has substance, but the Z06/ZR1 is no lumber wagon
when it comes to NVH suppression.

It would be nice to some day hear about 'feel' from a reliable source
and/or to see NVH and stiffness numbers for the SLR.

.

Slalom4me

Again. The point of the thread wasn't to compare the SLR/C6.

I merely brought forward the picture of the chassis because the f-clip
is unusual for me.

.

ghoffman

OK, back on the point, I am surprised that they used a truss that has basically a tubular "X" structure. Typically, shear panels are more effcient, and the non-linear analysis methodology for crash resistance are well known. In addition, shear panel structures are usually easier to make in an autoclave. I would like to hear what they were thinking.

BrianCunningham

That struck me as the oddest thing.

They should have kept the monocoque scheme going.

While they were at it encapsulate some crash aborbing foam.

MJM

apples and oranges....the only thing survivable in the future will be stealth. Everyone who has ever flown BFM would love to have a "light weight fighter" to whip up on other airplanes in canned within visual range scenarios. It's all moot though if you aren't low observable because you will be shot down long before you get close enough to do any turning.

Solofast

Agreed, but maybe they were looking for a specific controlled rate of defomation. Thin shear structures tend to buckle so maybe they were trying to get a structure that would resist buckling, and by the time they did that they had more strength and stiffness than they needed for the chassis. Also for controlled deformation it may be advantageous to put foam into the tubular structure to also help control the deformation rate.

Clearly just thoughts and engineering guestimates, but there can be reasons to do things that are not obvious unless you have all of the inputs that they did when they designed it. In my experience, given the same problem set, good engineers will often end up with similar results......