Prodrive Mini

i wonder how much it changes things by using the b-pillar?

it could be easy to make the lower bar straight and integrate four vertical studs connecting the two continuous bars.

doesnt say how far apart the sill bar has to be from the other 2 bars. or how big the 4 vertical studs need to be.



Edited 1 time(s). Last edit at 06/17/2011 07:08PM by Greg Donovan.

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NoCoast
They've always been allowed in the US cause people have always chosen to do them. But never seen a single other country with a rally car with those types of doors.

i interepeted the above statement to mean US didnt allow 'em anymore when you meant no other series.

maybe they dont want to use them due to weight? NASCAR is too american?

I believe actual NASCAR door bars start at a real frame, are 2" tubing and covered in a sheet of steel when done.

Bars that are bowed out give more room and absorb a certain amount of energy as they deform. That deformation is the issue to date. Once they start bending they tend to keep bending. We tend to slam trees or the occasional fence post...narrow impact..large load. NASCAR and road race stuff tends to more of a square impact from a bumper or wall..large impact smaller load. Best bet is don't crash...

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heymagic
I believe actual NASCAR door bars start at a real frame, are 2" tubing and covered in a sheet of steel when done.

Bars that are bowed out give more room and absorb a certain amount of energy as they deform. That deformation is the issue to date. Once they start bending they tend to keep bending. We tend to slam trees or the occasional fence post...narrow impact..large load. NASCAR and road race stuff tends to more of a square impact from a bumper or wall..large impact smaller load. Best bet is don't crash...

so a x bar or sill bar with single door bar that is straight doesnt deform inward as much?

i ask because i am in the process of budgeting and figuring out what type of door bars to put into a 95 open light impreza sedan.

what is your opinion of these bars if they showed up in a US built impreza sedan waiting for a logbook?

You may want to investigate this thread on corner-carvers.com...

http://forums.corner-carvers.com/showthread.php?t=27556

The good shit starts around page 13, and pay attention to Blaine Fab posts...

---

SteveL
This is the point in the killing spree when you really should turn the gun on yourself

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Greg Donovan

so a x bar or sill bar with single door bar that is straight doesnt deform inward as much?

i ask because i am in the process of budgeting and figuring out what type of door bars to put into a 95 open light impreza sedan.

what is your opinion of these bars if they showed up in a US built impreza sedan waiting for a logbook?

The advantage that the X, or sill bar and single door bar, have is that they are in tension when loaded in a side impact. So for them to deform the bars have to either stretch/rip, pull apart at the welds, or pull the legs of the main hoop/half lateral inwards. The nascar style door bars just have to bend to deform inwards because their total length is longer than the distance from the main hoop to the a pillar. I'm certainly not qualified to say which is better, but thats how I understand the two designs differ with regard to how they take loads from a side impact.

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Carl S

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Greg Donovan

so a x bar or sill bar with single door bar that is straight doesnt deform inward as much?

i ask because i am in the process of budgeting and figuring out what type of door bars to put into a 95 open light impreza sedan.

what is your opinion of these bars if they showed up in a US built impreza sedan waiting for a logbook?

The advantage that the X, or sill bar and single door bar, have is that they are in tension when loaded in a side impact. So for them to deform the bars have to either stretch/rip, pull apart at the welds, or pull the legs of the main hoop/half lateral inwards. The nascar style door bars just have to bend to deform inwards because their total length is longer than the distance from the main hoop to the a pillar. I'm certainly not qualified to say which is better, but thats how I understand the two designs differ with regard to how they take loads from a side impact.

Boys, study stone arches, start with Acropolis (no arches), then the Romans

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"The ancient Romans learned the arch from the Chinese and Etruscans, refined it and were the first builders to tap its full potential for above ground buildings:

The Romans were the first builders in Europe, perhaps the first in the world, fully to appreciate the advantages of the arch, the vault and the dome.[6]

Throughout the Roman empire, their engineers erected arch structures such as bridges, aqueducts, and gates. They also introduced the triumphal arch as a military monument. Vaults began to be used for roofing large interior spaces such as halls and temples, a function which was also assumed by domed structures from the 1st century BC

then move on the Romanesque, and then study the great Cathedrals of Europe. Arches and domes are always stronger than equivalent straight constructions made from same materials.

Think for just a moment: a tube w/ x wall horisontal that is 100 feet long securely held. All this nonsense of "in tension" won't prevent deflection downwards when T weight is placed in the middle.

Now imagine a arch, same material, and same span. Weight T placed in the middle has its force dissipated, lead away to some degree BEFORE it can begin to deflect the tube inward.

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The arch is significant because, in theory at least, it provides a structure which eliminates tensile stresses in spanning an open space. All the forces are resolved into compressive stresses. This is useful because several of the available building materials such as stone, cast iron and concrete can strongly resist compression but are very weak when tension, shear or torsional stress is applied to them. By using the arch configuration, significant spans can be achieved. This is because all the compressive forces hold it together in a state of equilibrium. This even applies to frictionless surfaces. However, one downside is that an arch pushes outward at the base, and this needs to be restrained in some way, either with heavy sides and friction or angled cuts into bedrock or similar.

This same principle holds when the force acting on the arch is not vertical such as in spanning a doorway, but horizontal, such as in arched retaining walls or dams.

Even when using concrete, where the structure may be monolithic, the principle of the arch is used so as to benefit from the concrete's strength in resisting compressive stress. Where any other form of stress is raised, it has to be resisted by carefully placed reinforcement rods or fibres. (See Arch bridge.)

the results of force is always dependant on angles and pure compressive (think a tube on end and force on the end of the tube). Is one end of strength scale--and perpendicular is the other end.

Think of the thin cell walls of cellulose that support TONS of tree above in compressive, but which splinter when force is applied perpendicularly.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

there are the two camps on bars going out into the doors.

john, do you think it makes a difference that many (most) of the bent bars are not true arches? but rather a bar with a 35* to 45* bend on each end of the tube.

i suppose the bars that run up through the firewall to the front strut towers and the lower rear stay from base of main hoop to rear strut towers can be viewed as butresses.

with the dash bar and the rear crossbars being the arch supports.

Honestly there is no comparison between a roman arch under a bridge and a door bar nor should there be.

Once a steel or aluminum hollow tube gets crushed and loses its shape it gets very weak at that area and starts bending quite easily. A tube in tension is still able to be crushed but instead of just hinging in it pulls the A and B pillar tubes inward with it. It does more damage to the cage (replaceable) and hopefully less damage to the occupant( not so replaceable). We never know how a rally car will be impacted so the perfect set of door bars cannot be made.

Side intrusion in cars is one of the hardest things to mitigate. If you ever seen the old films of a Chevy pickup getting slammed in the side...drivers head hit side of cab, driver rendered unconscious, outboard fuel tank erupts....We don't know if someone will hit a tree at 100mph or a dirt bank at 20mph. How do you engineer for that variety? We need bigger interior spaces to allow for occupant movement, better containment so occupants don't move, better exterior protection with more energy absorbtion. Very complicated.

Since the Martin/Park tragedy the FIA stepped up research into side protection. I believe that is still ongoing with composite material, seat desing and shell testing.

The Mini design will be accepted initially by the FIA because of homolgation...some engineer will submit paperwork stating it meets certain load conditions and the FIA will accept it. It may work in the real world or it may not. I've seen pics of frightening tears in the thin T45 crap tubing that is legal thru homolgation so who knows. Homolgation engineering is far from foolproof. Right now if you bring me a design like the Mini you get no logbook. Both NRS and RA has an outward bent door bar formula (unfortunately it isn't quite the same for both).

Bottom line is don't build a brick arch on the outside of your rally car

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heymagic
Honestly there is no comparison between a roman arch under a bridge and a door bar nor should there be.

Once a steel or aluminum hollow tube gets crushed and loses its shape it gets very weak at that area and starts bending quite easily. A tube in tension is still able to be crushed but instead of just hinging in it pulls the A and B pillar tubes inward with it. It does more damage to the cage (replaceable) and hopefully less damage to the occupant( not so replaceable). We never know how a rally car will be impacted so the perfect set of door bars cannot be made.

Side intrusion in cars is one of the hardest things to mitigate. If you ever seen the old films of a Chevy pickup getting slammed in the side...drivers head hit side of cab, driver rendered unconscious, outboard fuel tank erupts....We don't know if someone will hit a tree at 100mph or a dirt bank at 20mph. How do you engineer for that variety? We need bigger interior spaces to allow for occupant movement, better containment so occupants don't move, better exterior protection with more energy absorbtion. Very complicated.

Since the Martin/Park tragedy the FIA stepped up research into side protection. I believe that is still ongoing with composite material, seat desing and shell testing.

The Mini design will be accepted initially by the FIA because of homolgation...some engineer will submit paperwork stating it meets certain load conditions and the FIA will accept it. It may work in the real world or it may not. I've seen pics of frightening tears in the thin T45 crap tubing that is legal thru homolgation so who knows. Homolgation engineering is far from foolproof. Right now if you bring me a design like the Mini you get no logbook. Both NRS and RA has an outward bent door bar formula (unfortunately it isn't quite the same for both).

Bottom line is don't build a brick arch on the outside of your rally car

Gene the point of looking at the basically weak materials is to lead folks thru the steps that civilisation did.... so the concepts were shown: arches and domes lead force away first BEFORE they begin to deform..
I coulda said doooooods its fawkin first week of Injur-nearing 101 (vectors) but then I'd just be repeating what some injur-near said once...
And we all know about injur-nears.

It is always a good idea to see where an idea would lead is to exaggerate one element in isolation (conceptually) to see the ultimate tendancy.

It is also worthwhile to check what terms actually mean so we can avoid the 'conversationally true" but practically insignificant" type error of thinking.

---

John Vanlandingham
Sleezattle, WA, USA

Vive le Prole-le-ralliat

www.rallyrace.net/jvab
CALL +1 206 431-9696
Remember! Pacific Standard Time
is 3 hours behind Eastern Standard Time.

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NoCoast
It might just be perspective but stuff looks small there.
http://3.bp.blogspot.com/-DjZRZNOhCds/TfOD-Tn7c_I/AAAAAAAAAMo/01TpQHh-cQo/s1600/09062011404.jpg

Specifically the compression strut and the thread diameter on the rod end for the TCA and the bolts for the strut to upright.

Grant, they could be using shoulder style bolts

sent an email to Mike Hurst to see his opinion of these bars.

just like grant thought, he mentioned that they would be used with the FIA door protection.

Everyone needs to remember that you can homologate a straw from McDonald's if you can get an engineer to sign off on it.

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Robert.

"You are way too normal to be on Rally Anarchy." Eddie Fiorelli.

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Rallymech
Everyone needs to remember that you can homologate a straw from McDonald's if you can get an engineer to sign off on it.

Prezactly....

Also...we/you cannot copy a homolgated design as such.

Is "FIA door protection" a piece of equipment or a legal document?