REFLECTOR: Accident report - SQ2000
Terry Miles
terrence_miles at hotmail.com
Sat Sep 24 08:46:48 CDT 2005
Jim,
Thanks for the backgrounder. I understand about stroke length and
trying to sort out among ourselves the best of the alternatives. I
noticed in your retort to my suggestions that it begins with the words
"Long ago..." Maybe there's been further improvement in chemical
engineering since you sat on a Martin Baker. I did too, back in the
late 60's.
I have no pony in this race, just trying to be sure we all look at the
options and compromises and make an informed decision. Stroke length
(ie deceleration/acceleration to the rearward) in part has to do with
terminal velocity when your compressible material is flat. Velocity
squared, remember. Density factors cannot be equated to mere thickness
within this consideration for best alternatives. The cushion I am
building up is a complex of 3 different materials. This stuff does not
compress easily when spread across contour that you yourself establish
across its upper layer...It is not a cushie pillow, and can get like a
rock when chilled. It is not 1 inch thick. It is never less than 2 and
body-conforming slide bolters, lumbars etc go up to over 4 inches. The
bigger your backside the more square inches (including bolsters) that
you will have to compress before you decelerate your tailbone into solid
surfaces. Confor Foam is the trade name, they sell it because it's
comfortable and meets FAR burn specs and it is among the best seat
material available to us.
If somebody designs a crumple zones like you see in the Volvo ads, I'm
all for it...except that Volvo's go in a straight line along an
established surface...trying to design one for a light aircraft
(spherical) is a tall order, but a worthy goal. I'm always attentive to
a better mousetrap. That's what we are all about here.
Terry
-----Original Message-----
From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
Behalf Of Jim Sower
Sent: Saturday, September 24, 2005 12:27 AM
To: Velocity Aircraft Owners and Builders list
Subject: Re: REFLECTOR: Accident report - SQ2000
<... Here is a link (oregonaero) for you ...>
Long ago in another life, I was heavily involved in ejection seats. The
major players at the time were Martin-Baker and RAPEC. M-B used more or
less a cannon shell in a telescoping tube to get maybe a 15' - 20'
stroke. Paralysis wasn't assured, but significant spinal injury pretty
much was - particularly if you weighed more than 160 lb). The "seat
cushion" was WOOD. Anything softer would allow the seat to build up a
good head of steam before it hit your ass and assure paralysis. RAPEC
OTOH incorporated a rocket with maybe a 100' - 150' stroke. It was 8-10
Gs compared to M-B's 20 Gs or more. Interestingly, RAPEC could use soft
seat cushions and still out perform M-B (you could eject successfully in
the chocks while with M-B you needed 80 - 100 kts forward motion). M-B
was experimenting with the precursor to memory foam, but filling it with
liquid. It would slowly migrate to fit your butt comfortably, but be as
incompressible as wood when you ejected.
The lesson here is clearly stroke length. M-B had 15', RAPEC had 150'.
Which was more comfortable (you only get one guess :-)? Crushable
structure in the airframe buys us a longer stroke than a rigid
structure. Seat cushions don't add anything consequential to the stroke
length.
I'm not aware of anyone successfully designing a crushable structure
(like in race cars) that would work in an airplane. Go for your
lastafoam seat. Compared to me in my cheap-ass bench, you'll be much
more comfortable when we both die in similar crashes.
If you think it enhances your survival chances, great - go for it - be
happy ... Jim S.
Terry Miles wrote:
>Jim,
>Here is a link for you http://www.oregonaero.com/p4243_2001.html
>If you ask, Oregon Aero, they will tell you that the buy the foam from
>Hi-Tech foam. Same way that Spruce buys their Scroth seatbelts from
>Karas Engineering who has the exclusive N.Am franchise. My info on
this
>differs significantly from yours. I've been told it does protect you.
>
>Terry
>
>-----Original Message-----
>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org] On
>Behalf Of Jim Sower
>Sent: Friday, September 23, 2005 5:18 PM
>To: Velocity Aircraft Owners and Builders list
>Subject: Re: REFLECTOR: Accident report - SQ2000
>
>
><... At some G-loading it's the body that would break anyway and not
>the seat...> Actually, I think the rigidly anchored, form fitting,
>temper/memory foam covered seats that have been discussed will kill you
>quicker than the factory seats. Crash survivability turns on structure
>crushing/breaking and absorbing energy. The factory seats have [a
>little of] that. Temper foam (or any other cushion for that matter) is
>comfortable, but useless for absorbing impact energy. A good 4-point
>restraint is as good as you can do IMO, but I haven't seen one in a
>Velocity. Cozys and EZs have them, but they have rigid, structural
>seats, so there's no impact energy absorption.
>
>Composite planes are just too damn strong to be crash worthy ... Jim S.
>
>
>
>Carruth, Joel L wrote:
>
>
>
>>I agree that the seats are a somewhat flimsy. However, correct me if I
>>missed something here, but from the last picture (100-3047) of the
>>
>>
>cockpit, it appears that the hinges are still intact - at least not
>broken. It looks more like the #10 screws were either sheared off or
>pulled from the aluminum hard point.
>
>
>>Assuming you stay with the factory seat (less $), it seems that the
>>following would be necessary:
>>1) Instead of #10s, use some AN-3s. With a doubler+nutplate on the
>>
>>
>inside.
>
>
>>2) Extra glass (3 BID??, UNI?) moving up the sides covering the
>>
>>
>aluminum attach point and doubler. Perhaps some UNI going from
>side-to-side at shoulder blade height.
>
>
>>Probably not as good as an engineered seat, but it will definitely
>>help. At some G-loading it's the body that would break anyway and not
>>
>>
>the seat.
>
>
>>Any other reinforcement ideas?
>>
>>Joel Carruth
>>Lockheed Martin
>>JSF - Pilot System Software
>>W: (817) 763-4337
>>Fax: (817) 777-8378
>>joel.l.carruth at lmco.com
>>
>>-----Original Message-----
>>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>On
>>
>>
>
>
>
>>Behalf Of Scott Derrick
>>Sent: Thursday, September 22, 2005 7:21 PM
>>To: Velocity Aircraft Owners and Builders list
>>Subject: Re: REFLECTOR: Accident report - SQ2000
>>
>>There are seats for race cars available that are very light and
>>designed
>>for high speed car crashes.
>>
>>I ave an 97 Std. and the seats are part of the air frame. I can't see
>>them coming apart, but I also can't seem them offering any crush to
>>lessen thr impact.
>>
>>Scott
>>
>>Chuck Jensen wrote:
>>
>>
>>
>>
>>
>>>The solution that was put into my plane was seats out of a Corvette.
>>>They are low profile (to enable the low-slung Vette look) and seem to
>>>be substantial, yet don't seem to weight much. Semi-reclining type
>>>auto seats may be worth a look.
>>>
>>>Chuck
>>>
>>>-----Original Message-----
>>>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>>On Behalf Of Tom Martino
>>>Sent: Thursday, September 22, 2005 12:37 PM
>>>To: Velocity Aircraft Owners and Builders list
>>>Subject: RE: REFLECTOR: Accident report - SQ2000
>>>
>>>This comes at the exact time that I pulled my seats because I decided
>>>they are flimsy. One day while flying in chop ... I felt my self
>>>being bounced a couple of times up against the seat back ... and I
did
>>>
>>>
>
>
>
>>>not like the feeling. The seat back seems weak.
>>>
>>>
>>>I am molding buckets that attach to the floor directly. The
>>>"buckets"
>>>
>>>
>
>
>
>>>will be lined with a system of shock absorbing material (like in a
>>>helmet) with memory foam on top.
>>>
>>>The bucket is one piece bottom and back, with some flex ... but no
>>>"joints". It will cradle my body somewhat like a clam-shell. I call
>>>it a seat helmet or "pod".
>>>
>>>I totally agree with many accident findings that forced landings and
>>>rapid descents often turn fatal due to inadequate restraint, shock
>>>absorption and seat structure. I hope to overcome these weaknesses.
>>>
>>>Tom Martino
>>>
>>>-----Original Message-----
>>>From: reflector-bounces at tvbf.org [mailto:reflector-bounces at tvbf.org]
>>>On Behalf Of Jim Sower
>>>Sent: Thursday, September 22, 2005 10:10 AM
>>>To: Velocity Aircraft Owners and Builders list
>>>Subject: Re: REFLECTOR: Accident report - SQ2000 [heur]
>>>
>>>I seem to recall that Paul bought his seats from Velocity - along
>>>with some other things. I never liked the seat structure but accepted
>>>that,
>>>
>>>
>
>
>
>>>like spam cans, the seat has little or nothing to do with restraint -
>>>the harness being bolted to the airframe. I further assumed that the
>>>seat structure would crush on vertical impact and therefore be of
some
>>>
>>>
>
>
>
>>>benefit in absorbing energy. I'm skeptical about the plane springing
>>>backwards as I am about intimations that he was flying out of limits
>>>
>>>
>aft CG.
>
>
>>>I assumed that the Velocity restraint structure had been tested
>>>satisfactorily ... Jim S.
>>>
>>>Al Gietzen wrote:
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>>Some of you may have seen this on other venues. This is not happy
>>>>reading but I post it here because of one factor that relates to our
>>>>airplanes - the seats.
>>>>
>>>>You can skip the rest of the report, but note that the lack of
>>>>seatback support is cited as a cause in the pilots death. The seat
>>>>is
>>>>
>>>>
>
>
>
>>>>essentially the same as the Velocity. From the first time I saw the
>>>>Velocity seats I was very concerned that is provides very little
>>>>support against strong forces vertically or from the rear. Once the
>>>>back support breaks there is no longer a restraint system.
>>>>
>>>>And speaking of restraint system, I also pressed the factory years
>>>>ago
>>>>for some test of the 5/16" bolt threaded into ¼" aluminum block as
an
>>>>
>>>>
>
>
>
>>>>adequate seat belt attachment; particularly for the inboard side of
>>>>the front seat.
>>>>
>>>>The analysis of the 4 canardians who examined the wreckage of Paul
>>>>Conner's aircraft is now available at:
>>>>
>>>>
>>>>
>>>>
>>>>
>>http://www.cozybuilders.org/N2992_Accident_Eval/
>>
>>
>>
>>
>>
>>>>Al
>>>>
>>>>--------------------------------------------------------------------
>>>>-
>>>>---
>>>>
>>>>_______________________________________________
>>>>To change your email address, visit
>>>>http://www.tvbf.org/mailman/listinfo/reflector
>>>>
>>>>Visit the gallery! www.tvbf.org/gallery
>>>>user:pw = tvbf:jamaicangoose
>>>>Check new archives: www.tvbf.org/pipermail
>>>>Check old archives:
>>>>http://www.tvbf.org/archives/velocity/maillist.html
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>>_______________________________________________
>>>To change your email address, visit
>>>http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>>Visit the gallery! www.tvbf.org/gallery
>>>user:pw = tvbf:jamaicangoose
>>>Check new archives: www.tvbf.org/pipermail
>>>Check old archives:
>>>http://www.tvbf.org/archives/velocity/maillist.html
>>>
>>>
>>>_______________________________________________
>>>To change your email address, visit
>>>http://www.tvbf.org/mailman/listinfo/reflector
>>>
>>>Visit the gallery! www.tvbf.org/gallery
>>>user:pw =vbf:jamaicangoose
>>>Check new archives: www.tvbf.org/pipermail
>>>Check old archives:
>>>http://www.tvbf.org/archives/velocity/maillist.html
>>>_______________________________________________
>>>To change your email address, visit
>>>
>>>
>http://www.tvbf.org/mailman/listinfo/reflector
>
>
>>>Visit the gallery! www.tvbf.org/gallery
>>>user:pw =vbf:jamaicangoose
>>>Check new archives: www.tvbf.org/pipermail
>>>Check old archives:
>>>http://www.tvbf.org/archives/velocity/maillist.html
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>>
>>_______________________________________________
>>To change your email address, visit
>>http://www.tvbf.org/mailman/listinfo/reflector
>>
>>Visit the gallery! www.tvbf.org/gallery
>>user:pw = tvbf:jamaicangoose
>>Check new archives: www.tvbf.org/pipermail
>>Check old archives:
>>http://www.tvbf.org/archives/velocity/maillist.html
>>_______________________________________________
>>To change your email address, visit
>>http://www.tvbf.org/mailman/listinfo/reflector
>>
>>Visit the gallery! www.tvbf.org/gallery
>>user:pw =vbf:jamaicangoose
>>Check new archives: www.tvbf.org/pipermail
>>Check old archives:
>>http://www.tvbf.org/archives/velocity/maillist.html
>>
>>
>>
>>
>>
>>
>_______________________________________________
>To change your email address, visit
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery! www.tvbf.org/gallery
>user:pw = tvbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>_______________________________________________
>To change your email address, visit
>http://www.tvbf.org/mailman/listinfo/reflector
>
>Visit the gallery! www.tvbf.org/gallery
>user:pw =vbf:jamaicangoose
>Check new archives: www.tvbf.org/pipermail
>Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
>
>
>
>
_______________________________________________
To change your email address, visit
http://www.tvbf.org/mailman/listinfo/reflector
Visit the gallery! www.tvbf.org/gallery
user:pw = tvbf:jamaicangoose
Check new archives: www.tvbf.org/pipermail
Check old archives: http://www.tvbf.org/archives/velocity/maillist.html
More information about the Reflector
mailing list