homebuilt safety

Pete Schaefer wrote:
Hey Jim-Ed:


"Jim-Ed Browne" wrote in message
om...

Is this because none of the ones available as designs currently have
any, or because you feel it's not feasible, or because....exactly why?


I've never looked at any airplane designs that have such features. There is
a huge price to pay in terms of weight, required power and such to provide
pilot protection. Drives up cost a ton, and makes operations more
expensive.


Don't mean to tell you your business, but....bulls417!!

See my website for PICTURES of proof. Crumple zones are not only
feasible, reliable, and light, but they've been flying for over 40years.

Sure, it's feasible, but it's expensive. How many airframes do you want to
build for the purpose of destroying them to prove the design? Then there's
costs of test facilities. What's the cost in weight, performance, etc.? How
much is it going to cost to design, model, and test? If you see a couple of
zeros being added on to the total cost to build and get the FAA to sign it
off, then you're probably getting a realistic picture.


No extra cost or weight, and why would you get the FAA to sign off on a
homebuilt aircraft design? It won't cost any more to design, model and
test than any other homebuilt design. Why would you need to do
destructive testing? Do I have to break my wings to prove they will
hold me up in flight?

I guess the question I have is this: How much are you willing to spend to
get an airplane that protects you in case of a crash? If you've got
millions to spend, then you can probably get what you want. But on a $50k
home-built? Forget it. Maybe a certified commercial manufacturer would have
the resources to pursue safety features like this, but I would find it
surprising if people would be willing to fork out the extra bucks for it,
given that the costs would have to be recovered through the sale of a
relatively small number of airplanes.


My goal is to stay well under $20k. One builder lost his engine and
didn't make the airport. Buried his Delta in a barnyard silo after
passing it through a bale of hay. Walked away from it. If you can keep
the landing to an acute angle crumple zones WILL help.

There are probably much better approaches to achieving leaps in aviation
safety without doing anything about crashworthiness improvments. Think
about the safety improvements you'd get just by having a more reliable
powerplant and fuel delivery system. Think about potential improvements
from sophisticated engine health monitoring (condition-based
maintenance....catch and repair faults before they become
catastrophic...there are some really nice products out there right now)?
Then there are potential benefits for IFR/night flight using synthetic
vision to prevent spatial disorientation. These kinds of improvments might
cost thousands of dollars to the consumer, falling in the range of what is
affordable to the typical RV builder at least.


From the statistics, the fuel delivery reliability rest most directly
on the pump in the fuel truck back at the airport. There ain't any
hardware that can fix that fault. It's a software problem 8*)

As for the rest of that...now who's talking about spending big dollars?
Crashworthiness should be part of the primary structure. Not a heavy,
expensive afterthought.

Anyway, just some things to think about. If you dig around for some of the
data on NASA's General Aviation Revitalization effort (no longer going on, I
think), you can find more comprehensive info on these topics.


Pete

P.S. Just to qualify my views - I'm not an airframe designer, but I do work
in aircraft development. I'm a flight controls engineer (meaning that I'm
one of the guys who's found ways to drive up the costs of an airplane
without driving the weight up) with Lockheed in Palmdale, CA. While I don't
work directly with these design/development trades, I am regularly exposed
to the issues and compromises that they bring up. So...knowledgable, but
not an expert.



When I sit in my incomplete project, I can look around at all the steel
that has to bend before the outside gets to me, I can imagine all the
fiberglass that will have to give way, and even if I'm no safer than in
the aluminum can I trained in, I certainly feel that way. There are not
any electronics or flight systems that will ever make me feel safer than
several feet of protection between me and the hard stuff.


--
http://www.ernest.isa-geek.org/
"Ignorance is mankinds normal state,
alleviated by information and experience."
Veeduber