[sharc_biker]

I have had this question in my mind for a long time now. We all know that when it comes to crash safety, a tough and rigid all round body/chassis can be detrimental to the passengers. What would perform well is a tough passenger shell with adequate crumple zones in the rest of the car which can absorb the impact of the crash. When a vehicle is bulletproof, all the additional ballistic armour, thick bulletproof glass, etc will add to the weight of the vehicle which in-turn increases the scale of impact during a crash. Will the existing crumple zones be adequate to fully absorb the impact of the vehicle when it weighs nearly twice as much?

With all the ballistic armouring even for the engine bay, doors and the rear of the car, will the crumple zones even crumple as they are designed to?

A recent news article related to the crash of a bulletproof Scorpio where the occupant claimed that everyone escaped unhurt because the car was bulletproof:

https://timesofindia.indiatimes.com/...w/63199668.cms

Some pictures of the Bulletproof Scorpio:

Would a non armoured Scorpio fare equally well?


The layered bulletproof glass does not shatter


Had the crash impact been more, would the ballistic armour be a boon or bane for the occupants?



Do other internationally reputed OEM armoured cars like the Mercedes S600 Pullman Guard, Knight XV, etc fare better in crashes than cars which are bulletproofed by third party companies?

Would the armoured S600 Pullman guard fare better in a crash when compared an equivalent non armoured version?

[SmartCat]

In the above case, the fact that the bullet proof Scorpio did not topple over implies that impact speed was quite low

Bullet proofing adds 500 kgs to 1 tonne of weight depending on level (ability to take on pistol bullets or AK47 bullets). Because of weight addition, I'd assume huge safety gains will be made if there is crash against lighter cars and SUVs. There will be some safety gains made if there is crash against heavier vehicles like trucks and buses, as long as speed is not excessive.

However, whatever gains you make in crash safety, you lose in terms of ability to avoid a crash in the first place.

1) Braking distance is likely to go up
2) Vehicle loses agility - you won't be able to swerve quickly
3) Increased risk of a roll over.

[ashis89]

IIRC, I read a report about the Princess Diana crash where Mercedes had issued a statement saying that the armoured Merc killed the occupants. Had it been a standard Merc, they would have survived or had greater chances of survival. I could be wrong here or this news could be irrelevant now since it happened a long time ago. Technology has advanced a lot in the meanwhile.

In a bullet-proof car, we need to figure out if the bulletproofing has been done only to protect against weapons or is it in sync with the overall structure of the car and it's crumple zones. Depends on how much engineering thought has gone into the process. If it is the former, under an impact, the additional metal added to the car body could dislocate and cause more damage to its occupants (this is what the Merc report said, happened in case of Diana crash).

If it is the latter, it could augment the strength of body and reduce chances of body deformation. I am a noob here and can't comment on where it will help the crumple zones or just transfer the energy to the other vehicle.

I would like to bring another line of thought. Bullet proofing increases the weight of the vehicle. When we consider the momentum and energy of this vehicle, it will be higher than a lighter vehicle. In the event of a crash, the vehicle would transfer a greater amount of energy to the other party and receive less energy. But this thought still doesn't answer if the bulletproof vehicle is capable enough to absorb the less energy.

Originally Posted by AutoNoob

I am aware of this video and the Mythbusters have rightly busted the myth, but with a caveat "crashing of identical cars". Here the structures of the two cars almost equally share/ dissipate the crash energy. Somehow, I am not at all surprised to see the general inference that you all have derived; most people get caught in this over-simplified 'lab' test. I wish the real life scenarios are also similar and thus occupants face less danger.

However, they aren't. I too might have been over simplistic in my earlier comment while trying to relate it more to the real life scenarios and thought process of average customers (and leaving out the bits of additional physics). Please consider the following in a real life crashes :

The scenario of having crash between two vehicles with similar masses and structural integrity is possible, but probability is much less than that involving two different vehicles. This becomes significant in case the two vehicles have significant difference in weight & structural integrity (say a K-Segment car and a SUV). In such case, due to the high mass difference, the SUV acts as more like rigid barrier. And with the SUV as frame of reference, the smaller car approaches it at a speed equivalent to the actual relative speed between the two vehicles.

In such a unequal sized collision, the heavier vehicle experiences lesser change in its velocity than the lighter car. Thus, inline with law of conservation of momentum, the impulse (rate of change of momentum) experienced by the smaller car is much higher the bigger SUV. Therefore, the smaller (lighter) car suffers more damage. Also, in most Indian cars in mass segment the structural integrity is questionable, the occupants are at a higher risk, even though both vehicles were travelling at same speeds.

The relative speed is important when the structural deformability of one body is significantly different than the other. Just think if the damage will be similar (1) in a head-on crash between a car and a train travelling at speeds of 30km/h each (2) car crashing in a static train/ wall at 30km/h. I am not quoting the usual highway scenario of car-truck collision as the mechanism is totally different due to no/pseudo FUPDs/RUPDs.

This is my understanding, and I'll be happy if you can correct my errors. Thanks !!

[sharc_biker]

Originally Posted by smartcat

In the above case, the fact that the bullet proof Scorpio did not topple over implies that impact speed was quite low

Bullet proofing adds 500 kgs to 1 tonne of weight depending on level (ability to take on pistol bullets or AK47 bullets). Because of weight addition, I'd assume huge safety gains will be made if there is crash against lighter cars and SUVs. There will be some safety gains made if there is crash against heavier vehicles like trucks and buses, as long as speed is not excessive.

However, whatever gains you make in crash safety, you lose in terms of ability to avoid a crash in the first place.

1) Braking distance is likely to go up
2) Vehicle loses agility - you won't be able to swerve quickly
3) Increased risk of a roll over.

How would a bulletproof car hold up in case of a crash against an immovable stationary object like a tree or a large concrete structure which will not offset any impact? IMHO, the added energy due to the heavier weight and the crumple zone compromises will turn the car into a death trap as the occupants will bear the brunt of it.

The gains made by hitting a lighter car/SUV will not help then. Would it be an absolute disaster for the occupants in case of a standard EuroNCAP/ IIHS Frontal & small Overlap crash tests against stationary structures?

[ajmat]

Originally Posted by ashis89

IIRC, I read a report about the Princess Diana crash where Mercedes had issued a statement saying that the armoured Merc killed the occupants. Had it been a standard Merc, they would have survived or had greater chances of survival. I could be wrong here or this news could be irrelevant now since it happened a long time ago. Technology has advanced a lot in the meanwhile..

It was a bog standard S-Class owned by the hotel.

Lets understand what modifications are made for bulletproofing

• Thicker bulletproof glass - more rigidity for sure
• Kevlar or carbon fibre lining of panels - stops bullets and explosions but really will not affect the rigidity of the car. Special Forces wear kevlar due to its flexibility
• Reinforced sheet metal - this is usually added to the floorpan in order to withstand explosions, improved rigidity but crumple zones might be affected and impact energy could get transferred to passengers

Summarising - there might a 5-10% improvement in my opinion.

[ashis89]

Originally Posted by ashis89

IIRC, I read a report about the Princess Diana crash where Mercedes had issued a statement saying that the armoured Merc killed the occupants. Had it been a standard Merc, they would have survived or had greater chances of survival. I could be wrong here or this news could be irrelevant now since it happened a long time ago.

Originally Posted by ajmat

It was a bog standard S-Class owned by the hotel.

OT: I was wrong about the Diana incident. I went through a few reports which confirm that the particular S280 had been stolen and totaled in an accident 2 years before this fateful crash. The car was repaired against general advice from most technicians and kept in service by a limousine company which supplied this car to Ritz.

http://www.independent.co.uk/news/uk...-a7765356.html

[GTO]

We can draw an analogy with bull bars - they will reduce damage at slow speeds, but can be a disaster at high speeds. Occupants of bulletproof cars might also forego the benefits of crumple zones, unless it's a factory build like the Mercedes S600 Guard.

Of course, like Smartcat said, it'll be poorer in the handling & braking departments, but then these VIPs are perhaps more worried about murder than accidents.

Another thought - crashing against a bulletproof car might actually be more dangerous for a regular car.

Originally Posted by ajmat

It was a bog standard S-Class owned by the hotel.

They were just asking for trouble, man. The driver himself had alcohol and Princess D hadn't even buckled up. Now we have Ashis89's post which says that it was a rebuilt accident car !

[anjan_c2007]

A few bullet proof car accidents and blasts from the past:

ex- President Giani Zial Singh, was seriously injured when his car (in Ropar dist.) collided head-on with a truck coming from the wrong side on 29/11/1994. He died on 24/12/1994 as a result of the multiple injuries. As ex- President, he was then entitled to a bullet proof Ambassador. But an Ambassador (in any avatar) surviving a crash head on with a truck is unimaginable !

http://www.independent.co.uk/news/wo...h-1388541.html

Again, in August 1995, Beant Singh, then CM of Punjab was killed when his bullet proof Ambassador exploded due to a bomb blast. He was leaving the Secretariat and was about to enter his car. The Ambassador was ripped apart. Here the VIP was outside the car.

http://www.tribuneindia.com/2010/20101013/main7.htm

Shri Chandrababu Naidu, the then CM of united Andhra Pradesh survived a bomb blast, when his bullet proof Ambassador was involved in a landmine-blast near Tirupati, in October 2003.

http://www.frontline.in/navigation/?...4004001800.htm

http://www.thehindu.com/2003/10/02/s...0207560100.htm

[audioholic]

Originally Posted by GTO

We can draw an analogy with bull bars - they will reduce damage at slow speeds, but can be a disaster at high speeds.
!

I second this. At low speeds, it will be like sitting in a safe locker. The vehicle will hardly suffer any damage beyond the outer skin, and so will the occupants be safe. At higher speeds, dynamics will change and maybe the vehicle might resist damage, but I am not sure of the occupants inside it, especially if the armor will alter the various crumple zones as well as impact protection bar in the sides.

Another aspect here will be the quality of work and type of work done. If the armor work is done in some shoddy manner, with panels screwed here and there inside the doors, floor etc then that will prove to be more dangerous since there will be a risk of these panels getting dislocated or intrude into the passenger compartment. However, bigger companies and the manufacturer itself would give higher emphasis on such issues when they offer an armoured variant.

[dark.knight]

Originally Posted by sharc_biker

Do other internationally reputed OEM armoured cars like the Mercedes S600 Pullman Guard, Knight XV, etc fare better in crashes than cars which are bulletproofed by third party companies?

Sure, the reasons are :

- Much higher spec armour plate with kevlar lining is used between the thicker than normal pressed metal of the car.. more resistance.

-Armassglass AG is the bulletproof glass in question, its antiballistic and has polycarbonate plastic inbetween and is literally shatterproof.

- The roof is highly reinforced and thus acts as a major pillar of the overall structure of the car.

- The base of the car is also heavily reinforced with structures that wont crumple and the floor pan as well is made bomb-proof with upto an inch-inch and a half of the strongest alloys known to man.

- The front and the engine will have several layers of protection because in an extreme situation where the car is blocked, the armored car should be able to push through and infact, collide with other cars and still make it out safely.

Crumple zones are useful for vanilla, everyday cars where affordability and fuel efficiency comes into play.. I strongly believe that weight helps in safety and in the case of armored cars its very true, it merely shakes a couple of inches this side and that side when a grenade is put beneath it.. a side impact from another vehicle will hardly push it a couple of feet sideways before it can regain composure and drive away. The weight essentially helps the car from being bullied by other heavy vehicles and it can perhaps even damage the offending vehicles to the extent that they do not work anymore.

I'm sure such vehicles also come with multiple airbags, more expensive seat restraint systems, much longer distance between the rear seat and front portion of the car, in-cabin oxygen supply, and first-aid kits to fully protect the occupant and to compensate for the super-rigid structure of the car. Crumple zones may be proven as a safety necessity but in this case that simply isn't an option.

[Dry Ice]

Originally Posted by smartcat

However, whatever gains you make in crash safety, you lose in terms of ability to avoid a crash in the first place.

1) Braking distance is likely to go up
2) Vehicle loses agility - you won't be able to swerve quickly
3) Increased risk of a roll over.

Excellent points and all of them make sense logically if you consider bullet proof cars are 'just' more metal to stop the bullets. But, most seem to have upgraded engines, suspensions, brakes, tyres, batteries - almost every key component is modified/improved**. So there might not be too much deterioration of the vehicle dynamics. And unlike regular cars, they are built for one purpose - to keep the occupants safe, come what may. They are built so they can keep moving even after damage - to basically assist an escape, to make sure the person doesn't become a sitting duck.

Thinking about these points, I would be really surprised if any of the 'proper' (coming directly from factory or built/modified in a comparable setup) bullet proof cars fare badly compared to the regular versions in accidents.

** Of course, the modifier matters a lot, whether you pick a factory supplied piece or get one done at your local mechanic.