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Racecar Engineering Head Restraint article
It is in the May 2004 issue of Racecar Engineering magazine (vol14, n5). "Head Masters" by Jonathon Ingram; pgs 44-52. If you don't have it please purchase this issue at www.racecar-engineering.com and support the magazine.
http://www.racecar-engineering.com/i...this/cover.jpg p. 44 http://tinypic.com/tywyh p. 45 http://tinypic.com/tyx4h p. 47 http://tinypic.com/tyx5d p. 48 http://tinypic.com/tyx5z p. 51 http://tinypic.com/tyx7b p. 52 http://tinypic.com/tyyhu |
The article discusses HANS, Hutchens, D-CEL, Simpson and G-Force (note Isaac isn't mentioned or tested). Quote from article below. Items in paranthesis added by me:
"There are two existing standards derived by engineers when it comes to the amount of head protection needed. John Melvin, an engineer who has tested head restraints for two decades and is a consultant on cockpit safety for NASCAR, believes the head and neck loading expected to result in a fatality is 4000 Newtons, a figure taken from a paper presented by three other scientists to the Society of Automotive Engineers in 1994. The US standard, meanwhile, is a slightly higher 4170 Newtons. It's an important issue because only one system, the HANS, consistently reduces the neck forces well below these generally accepted standards for the threshold of a fatal injury. The reason: the HANS eliminates load on the neck by transfering it to the shoulders, where the other devices (devices other than HANS merely) help carry the load. For that reason, Melvin also believes HANS should be adopted as the standard for judging the effectiveness of other devices. 'There's the HANS and then there's everything else. There doesn't seem to be anything else that comes close'. ...In december 2002, Melvin released the results of his comparison study of the HANS and the Hutchens device to the SAE. ...To establish a baseline Melvin's dummy with a standard safety harness but no head and neck restraint registered 5100 Newtons of neck tension, well beyond the fatal limit by any calculation. The test was conducted at a velcoity change of 35 mph, or the difference in speed before and after the crucial stages of the impact, using an aluminum seat with lateral shoulder support. (Note that this means that a collision with an immovable object from only 35 mph can be fatal in some cases!) ...(in this test) HANS limited the neck loading to 1121 Newtons, well below the limit. In the same tests, the Hutchens device limited the dummy's neck tension to 4000 (!!!) and the D-CEL results averaged 3971 (!!!), each close to the limit." |
As always, I'll be the cynic here, these tests were conducted by the seller of the Hans device, and the article states that the seat, and Harness type were not those recomended by the manufacturers of the other devices. Especially important as I mentioned before wasthe six point Harness with the D-Cel/Simpson unit. Further, if you read Melvins comments on this test as posted on his own site, he mentions that by loostening the D-Cel 2"(that is ALOT) that the results were substantially worse than if properly adjusted(that's a shocker). Also, he never states that the results listed in this article are the best results acheived with the two competing devices. I would love to see the actual papers presented to SAE, as opposed to Hype presented by the inventor of one of the devices. this article is no different than the articles on the other manufacturers sites, all of whom also used sleds, and had entirely different results. Another note is that the Hans relies upon your harness shoulder belts to protect you, in multiple impacts you may not be in those belts as required. To take it a step further, if you lack lateral restraints in your seat, the D-Cel will protect you in side impacts wher the Hans will not(as stated by Melvin. just do not believe that the tests on all the other sites are fabricated, and Melvin is the only one telling the truth. Also,D-cel has changed to a fabric with substantially lower elongation. my motivation for pointing all this out, is too often a popular concept or direction is made out to be the only "right choice". If I read that article correctly allthe staements as to Hans superiority are made by its inventor. Food for thought. I will be making an effort to Sample the D-Cel, as well as the Hans, and give some commentary back on fitting since this is so key to the performance of all the devices. Carl
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One would think those would have the full range of test results, let's hope so. So I am clear, I am NOT anti Hans by any means, I am pro whatever will keep opur members the safest given our typical car, belt, and seat configurations.
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Each of the papers costs $12. If we were smart we could organize and each of us purchase a different paper so hopefully we could collect a few. I think these are most pertinent but there's a goldmine full of research available from the SAE at www.sae.org
Sled Test evaluation of Racecar Head/Neck Restraints Sensitivity Analysis of the Hans Head and Neck Support Sled Test Evaluation of Racecar Head/Neck Restraints Revisited Atd Neck Tension Comparisons for Various Sled Pulses Biomechanical Principles of Racecar Seat Design for Side Impact Protection |
It seems that we could convince the manufacturers to publish their tests, I think they do not because none of the restraints shines in all situations. Hans seems best in a straight on, The D-Cel, for angles, and multiple impacts, and the Issac, probably similar to the D-Cel, although there is very little independent reporting on it. I am going to contact the folks at Simpson/D-Cel, and invite them to publish their full report here. Carl Byck
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Carl,
You might have difficulty getting anyone to share sensitive data here due to liability issues. I am not aware if SAE will allow any of it's reports to be displayed in the public domain without permission, and loss of revenue to SAE would be a concern to them. db |
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Bump and hopeful upload of the broken images/pages.
Are there any vendors that sell HNR on the forum that might be able to do some sorta sale or group buy on these devices? |
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