Lancair IV-P Down In San Diego

[SteveinIndy]

Properly restrained a human can withstand the high limits, lets say 70 g's... and walk away... Race drivers do it on Sundays.. . Take that same 70 G's and convert that to downward G's like a human would be subjected to in a flat spin pancaking into the earth and the person would be crushed into a 3 foot tall corpse.. Not a snowballs change in hell of surviving..

Without a stroking seat and/or an energy attenuating subfloor, almost without a doubt yes. With a stroking seat, there have been folks who survived more or less uncontrolled falls of a military helicopter after RPG and shoulder-fired SAM hits. I believe a couple of these have been reported (based on estimates) as at least 50 G vertically at the floor of the aircraft . That is where the difference between forces of the aircraft and loads on the victims can vary to a point where survival of an "unsurvivable" impact is possible with a bit more engineering. This was described in one of the Army soldier protection magazines put out for their safety engineers a while back. I contacted one of the safety guys I know at the Army's aeromedical branch and picking his brain about the details of the crashes when I read it. I will try to dig up the specific citation if anyone really cares.

Also, as a side note, de Haven reported several folks who survived long falls with impacts of >70 G with a couple including landing in a seated position. Granted, I wouldn't voluntarily choose to experience that as the more reasonable cutoff is somewhere around 25 G or less in the vertical axis.

I hesitate to bring this up, but G loads also have a duration that is most critical to survivability. The pressure graph should be a pulse, much like a Std Dev line with 1G at each end, and the excursion measured in mS or seconds. No human can survive 26 or 40 Gs sustained more than a few hundred mS, no matter the direction.

Good point about impulse time but I would like to make a couple of points. If memory serves, at least one of the Stapp sled runs exceeded 50 G with an impulse time of over 0.2 but the occupant (I don't think it was Stapp on that run) was rear facing. The good news is that most crash impulses peak for no more than 0.2 seconds. That is why you see survival above that threshold and why relying on 26 or 40 G as a cut off is questionable at best.

Also, I'm not a mech engineer, just an ole EE but the surrounding structure needed to support a restraint system of 40Gs on a 200Lb person would be pretty beefy. It could surely be done, but it wouldn't be painless to aircraft design.

It does have to be pretty beefy but it isn't as much of a tradeoff as you might think. It is much easier in a new design (such as the one I am working on) because you can take load paths, etc into account from the "wheels up" and from the clean sheet onward.

 

[Oakfish]

Hello all- I would like to find out more about this specific accident (San Diego---3 fatalities) that was the subject of this thread when it was created.

Would like to know the specific weather conditions at the time, & is it possible to get radio transmissions etc? How & where would you look if you wanted to learn as much about this accident as possible.

Thanks for any & all help.

 

[Fearless Tower]

Hello all- I would like to find out more about this specific accident (San Diego---3 fatalities) that was the subject of this thread when it was created.

Would like to know the specific weather conditions at the time, & is it possible to get radio transmissions etc? How & where would you look if you wanted to learn as much about this accident as possible.

Thanks for any & all help.

LiveATC.com has a live feed for MYF tower and SoCal approach - should be able to go to the archives page and look up the feed for the approx time and date that the accident happened.

 

[Oakfish]

Thanks! I pulled what I thought were the audio archives from the radio transmissions of MYF but I didn't hear anything in regards to the accident??

Does the NTSB still due complete investigations into experimental or home-built aircraft such as the Lancair IV-P? Sorry but I'm not schooled in this stuff so just not sure if the NTSB investigates these like they do other GA crashes.

Thank you.