One of the big problems with discussing "G" with non-survivability engineers is that they often forget it's not simply a matter of "X G = serious or fatal injury" but where the force was applied (over how much of the body) and how rapidly it was applied (onset) and duration.
Steve, the instructors at Arizona State told us of an accident where a worker survived about 100 Gs. He fell several stories on a construction site and landed on a pallet of bricks. The bricks did not yield at all. The victims body did compress a few inches. So the delta V was something like .001 second and stopping distance was about 3 to 4 inches. Bottom line the G pulse was of so short a duration that it was survivable.
bob
When were you out there? Do you remember who you were being taught by?the instructors at Arizona State
Yeah, there's the famous paper by De Haven about survival in freakishly long falls. http://injuryprevention.bmj.com/cont....full.pdf+htmltold us of an accident where a worker survived about 100 Gs. He fell several stories on a construction site and landed on a pallet of bricks. The bricks did not yield at all. The victims body did compress a few inches. So the delta V was something like .001 second and stopping distance was about 3 to 4 inches. Bottom line the G pulse was of so short a duration that it was survivable.
One of the best cases in there:
*- For those who are not medically trained, the occiput is the anatomical term for the back of the head.CASE 5A woman aged 21, 5 feet and 7 inches (170 cm) tall and weighing 115 pounds (52 kg) jumped from a 10th story window, falling 93 feet (28 meters) into a garden where the earth had been freshly turned and landing nearly supine on the right side and back, with the occiput* striking the soft earth.
Deceleration and acceleration of gravity—The decelerative distance was a maximum of 6 inches (15 cm), according to the marks in the earth, which varied for diVerent parts of the body. The velocity at contact was 73 feet (22 meters) per second (50 miles [80 km] per hour), and the minimum gravity increase was 166 g.
Injuries—This woman fractured a rib on the right side and the right wrist. There was, however, no loss of consciousness and no concussion.
Comment—Several people were standing nearby when this patient struck the ground. She talked almost immediately and wanted to arise but was not permitted to do so. She entered the hospital, where she remained for 12 days. The earth in the flower bed where she landed had been spaded to a depth of 6 or 7 inches (15 to 18 cm). The earth packed hard under the force of this fall, and the gravity increase was estimated to have mounted to more than 200 g toward the end of the decelerative movement.
Unfortunately in science what you believe is irrelevant.
"I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.
Steve, I was selected for the course in 78.
Landing in soft ground can increase Gs. Increases duration of the G pulse. Let me take you back to NASA tests at Langley using the gantry. http://www.nasa.gov/centers/langley/...-138-larc.html Interesting read and discusses the pendelum tests.
Piper provided un-airworthy Navajo airframes that were on the factory floor when the flood hit Lockhaven in the 70s. They were loaded with test dummies and slo-mo recorded as they arced down to impact on various surfaces. My class viewed the videos and the crash diagrams and measurements. We then calculated the vert, horiz and the resultant G forces. Interesting findings: (1) the impacts on several feet of dirt with sod overlay resulted in HIGHER Gs than on bare concrete, because forward motion was retarded to a greater degree. Make sense? Don't make gear up landings on sod. Landing on smooth concrete allows a long gradual decel and LESS Gs OVERALL. (2) The vert Gs caused the cabin roof to momentarily deform down several feet causing head and neck injuries to dummies. It then rebounded to a near original position and would have been undectected if not for slo-mo video.
I had bought a wrecked Luscombe and restored it. Prior to the owner dropping it in and nosing it over, his wife (a petit 100 lbs) hit hard on landing, cracked a couple of vertebrae and this distraction caused a ground loop. After restoring and flying the plane, I grew to love the fluffy seat cushions the previous owners installed. I could sink in half a foot (it seemed). Later at ASU, we were instructed in the principle of DYNAMIC OVERSHOOT. Thats when the occupant and airframe hit the ground, but the airframe stops its descent and rebounds back up. The occupants are separate from the airframe, continue to descend and finely meets the rising structure. Results in a multiple effect on vertical G. And likely was the cause of a 100 lb woman breaking her back. I cried when I removed the fluffy seat cushions.
My class at the Crash Survival Investigaters Course were from the FAA, military Flight Surgeons, Test pilots and Aero Engineers, etc. The head of the dept was Dr Turnbow. The assist head was Dr Harry Robinson. A retired USAF bomber pilot, he survived a post crash fire. He became a strong advocate of crashworthy design..He also developed and marketed crashworthy aux fuel cells for the Hughes/MD 500 helos. Many visiting lecturers. One that I enjoyed was BG Wm Spruance DE ANG who survived a T33 crash and severe burns. He died last year at age 94.
I still have a lot of data from the course including equations for calculating Gs for 6 - 8 different type G pulses. I also have the classic and extremely rare Turnbow Kinematagraph. Doc Turnbow totaly abhored graphs. He nontheless created the graph the night before graduation in respons to intense badgering. We also studied data from the familiar ASU crash tests with the Connie and DC-7. http://www.youtube.com/watch?v=QHZY0-XUmMA http://www.youtube.com/watch?v=zI-FkWJaVEs&NR=1
Bob
Unfortunately in science what you believe is irrelevant.
"I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.
Under certain circumstances, yes. However, it can also increase the deceleration distance which may diminish the overall "peak" G. That's more of a practical concern in a free fall scenario than an aircraft crash though because of the small distances involved.Landing in soft ground can increase Gs. Increases duration of the G pulse.
It's also one of the reason the bottom edge of a fire wall should be canted towards the tail. The "digging" in motion brings the aircraft to an abrupt stop or, in more dramatic cases, can cause the aircraft to flip "*** over eyes" (to quote my paternal grandfather).
Ah....NASA Langley, one of the few NASA institutions doing truly useful research. I've gotten to know quite a few folks there over the past few years.Let me take you back to NASA tests at Langley using the gantry.
Would there be any way I could see that? Maybe get copies of the data, etc? Any other insights, information, etc you have to offer, I am very happy to hear it.I still have a lot of data from the course including equations for calculating Gs for 6 - 8 different type G pulses. I also have the classic and extremely rare Turnbow Kinematagraph. Doc Turnbow totaly abhored graphs. He nontheless created the graph the night before graduation in respons to intense badgering.
I met BG Spruance at an ERAU event several years ago as I was just getting started in my research. He was an interesting fellow to talk to. How I met him is actually quite funny. I was talking to someone about the subject and this older fellow was there listening to me and nodding. I pointed out how my policy has always been the old Russian adage of hope for the best and prepare for the worst. The retired military pilot I was talking to told me I was being overly pessimistic and the old man spoke up and told him to (and I quote) "shut it". The response was "YES GENERAL!". He introduced himself and we started to talking. Every one of my presentations since then has began and ended with a bit of advice I was given by BG Spruance: "Always be prepared for the worst and allow yourself to be pleasantly surprised when you don't crash".One that I enjoyed was BG Wm Spruance DE ANG who survived a T33 crash and severe burns. He died last year at age 94.
Some other pointers from a very wise man:
http://www.spruance.com/Crash_Surviv...h_survival.htm
Last edited by steveinindy; 06-11-2012 at 11:38 AM.
Unfortunately in science what you believe is irrelevant.
"I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.
That's exactly the argument I used with them and the guys from BRS. "If you can drop an Abrams out the *** end of a military cargo jet and not have any problems...." LOLYa know, for 7500 lb I bet you could adapt one of the LAPES chute systems they use to drop a Sheridan out the back of a C130
Unfortunately in science what you believe is irrelevant.
"I'm an old-fashioned Southern Gentleman. Which means I can be a cast-iron son-of-a-***** when I want to be."- Robert A. Heinlein.
Would there be a chance to see the material? Shucks yeah. I have 22 pages, too much to post here on the forum. A littler bad news is that both my all-in-one desk units are inop in "scan" mode. (They have HP logos) I do have fax capability. And there is always snail mail.
PM me
Bob