Horizontally Opposed Man

Hey so a sobering accident at VIR this weekend won't go into the details but does anyone know if one of the HANS type devices like R3 or efender are any better at protecting against injury in Lateral deceleration incidents?TIA HOM

Circuit Motorsports

Hope you're okay and the worst is just a bit sore.

Just some foundation on the terms I'll use.

Frontal impact (straight on)
Offset impact (the traditional 30 degree angled impact required by the SFI standard)
Side Impact (directly from the side /90 degrees)

I have yet to see any company release any test that showed devices and how they performed in a side impact. The tests required by SFI are frontal and offset.

The one that has the best test numbers is the Hybrid Pro from Safety Solutions (and what I now use for this reason). All of the SFI rated devices do decrease neck loads in the offset impacts. Some more than others.

For a true side impact the seat/halo/side nets will be the best form of protection. After that you are going to be making assumptions on how each device will perform in that full side impact direction.

For a great compilation of the test numbers you can look here in this spreadsheet.

http://www.racesafetydata.info/HNR.html

If you are up in the Triangle anytime soon I can put all of the devices in your hands and show you the differences.

Horizontally Opposed Man

Excellent advice thank you fortunately for me I was not in the incident.Second red flag I have seen at VIR in 10 years I guess.

gbaker

All SFI designs increase lateral shear loads,


and none perform as well as non-SFI designs in lateral torque,


Per SAE Paper #2006-01-3631.

RedlineMan

Hmmm...

Two items;

1) Having been accused many times of blowing the collective Isaac horn too
loudly and shamelessly promoting "his" product, what Gregg is saying in his
best PC language is that the Isaac Device encompasses more top performance
attributes than all the other devices out there. If you are not required to have
an SFI rated device, the Isaac should be your first choice. If you are required to
have an SFI device, then you are out of luck and must choose from the "lesser
performing" devices. If I had it to do over again, I would be using an Isaac.

2) Gregg, could you please explain what Lateral Shear and Moment are, for we
of lesser technical aptitude... which would be everyone here but yourself!

J richard

I hope this doesn't take this OT, but I've been wondering for some time if wearing a traditional neck collar in combination with a hans has ever been considered. The hans seems to do its job at the limit, while the collars provide basic helmet support. This is more for just comfort and neck ache rather than crashes, primarily lateral support, thoughts?...

Circuit Motorsports

Gregg, Just a point. The graphs you posted only have two SFI (of the >5) device and 2 Non-SFI devices.

ltc

5W-40
Diesel tow vehicle

RedlineMan

If I may;

Given the magnitude of the dynamic forces involved, a foam neck collar does nothing to reduce neck tension loads during a crash. In fact, in the extreme and abstract sense, they can actually make the situation worse, as they add to the mass that the H&N device is tasked with restraining.

They are fine for general driving comfort, if you like, but they won't do anything for you if it all goes wrong.

Veloce Raptor

Torque wins races. Horsepower sells cars.








Professional Racing and Driving Coach

924RACR

Yeah, it's been a while since we had a good rant battle in here...

I have an ISAAC and a HANS... guess which one I'm using this weekend!

ApexPerformance

I wouldn't recommend wearing a neck collar with a head & neck restraint as it adds mass to the helmet and head loads. However, it does support the weight of the helmet if your neck gets sore or you need the stabilization in rough conditions.

From www.Hansdevice.com FAQ
Can I wear a "horse collar" foam pad with a HANS Device?

Yes.
Foam collars are comfort accessories, not safety equipment. Wear one to stabilize your head and helmet on rough tracks.
Testing has shown a horse collar adds mass to the helmet and head loads that must be carried by the neck. This increases the chance of injury.

gbaker

Always at the ready.

gbaker

Those are the only products for which test data was available from test labs -- at the time of publication. Data from marketing departments was ignored.

gbaker

Thank you for the kind words, Sir. BTW, don't sell ltc short. I think there is some serious gearheading buried deep there.

The moment is the torque that bends the head left and right, as measured by the 3-axis sensor located at the junction of the neck and the head. The shear load is the load caused by linear forces working in opposite directions a that same location (see http://en.wikipedia.org/wiki/Shear_and_moment_diagram). The remaining type of load is the simple linear load of tension/compression.

So, we have three loads that occur about three axes, for a total of nine loads that can contribute to driver injury. SFI only considers two of the nine, the linear load which acts to pull the head up (Fx), and the bending load which acts to tilt the head back (My) during a typical crash. Neither measures side loads although the data is available for every test and is particularly valuable in offset tests where the side impact is 1/2 the total impact (sin 30 deg = 0.5).

Fortunately, all of this mumbo jumbo was examined by a famous 19th Century civil engineer named Mohr (http://en.wikipedia.org/wiki/Christian_Otto_Mohr) who distilled all nine loads into a single graphic representation which reveals the maximum unit stress and its orientation in the object. This representation is, as one might expect, referred to as Mohr's Circle (http://en.wikipedia.org/wiki/Mohr%27s_circle).

This is duck soup for any second year engineering student -- even those who later become lawyers.