homebuilt safety

"Pete Schaefer" wrote in message
newsQOqc.80298$iF6.6816727@attbi_s02...
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.

Keep in mind that crumple zones are only really for front impact, too.

Race cars go faster on the ground than some homebuilts will _straight
down_ and, Dale Earnhardt aside, usually people go in the wall and

They have requirements for driver protection. And they have huge budgets
to
work with. I don't know about about NASCAR, but, to get the sign-off to
race, the CART guys have to slam a couple of chassis into a wall to show
that the tub holds together. Expensive, expensive, expensive.

I recall that the P-51's designer, Dutch Kindelberger, designed the
cockpit area as the toughest structure, so everything else would
crumple around the pilot and provide protection from the sudden
impact. Is this somehow no longer feasible?

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.

Even if you could afford to buy one, operation costs of a P-51 is probably
well beyond the average budget of the typical home-builder. Besides, the
P-51 was designed to go to war and get shot at, not for $100 hamburgers.

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.

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.

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.



Yes, there are some negatives. However, re-enforced cockpits are becoming
the norm in sailplanes. Carbon-Kevlar composites provide a lot of
protection for the weight. Gliders land a lot more slowly than even RV's
but they are expected to land off airports without damage. If you
incorporate a ballistic parachute, re-enforced cockpits are required.

No amount of strengthening of the cockpit will save the pilot under all
circumstances but it might make a difference in some situations. A modest
amount seems a good idea.

Bill Daniels

It seems to me that such measures would be more important for a sailplane.
After all, you can't exactly go around if you botch the approach.


"Bill Daniels" wrote in message
news:KTPqc.80525$iF6.6835883@attbi_s02...
Yes, there are some negatives. However, re-enforced cockpits are becoming
the norm in sailplanes. Carbon-Kevlar composites provide a lot of
protection for the weight. Gliders land a lot more slowly than even RV's
but they are expected to land off airports without damage. If you
incorporate a ballistic parachute, re-enforced cockpits are required.

"Pete Schaefer" wrote in message
news:0cTqc.81388$iF6.6927599@attbi_s02...
It seems to me that such measures would be more important for a sailplane.
After all, you can't exactly go around if you botch the approach.

Not necessarily true, but also virtually never necessary. A good sailplane
gives you amazing glideslope control. With the spoilers fully deployed, I am
literally standing on the rudder pedals in some sailplanes approaching the
runway like a nicely controllable anvil; yet you can close them at any time to
instantly regain your full glide ratio, or modulate them anywhere in between.
It works! Just don't get low, slow, and downwind.

After years as a glider-guider (or a "dope on a rope" if you prefer) I have
finally taken up powered flight, and I am not at all sure that I have truly
internalized the concept that go-arounds are now an option.

Vaughn

"Vaughn" wrote in message
...

"Pete Schaefer" wrote in message
news:0cTqc.81388$iF6.6927599@attbi_s02...
It seems to me that such measures would be more important for a
sailplane.
After all, you can't exactly go around if you botch the approach.

Not necessarily true, but also virtually never necessary. A good
sailplane
gives you amazing glideslope control. With the spoilers fully deployed, I
am
literally standing on the rudder pedals in some sailplanes approaching the
runway like a nicely controllable anvil; yet you can close them at any
time to
instantly regain your full glide ratio, or modulate them anywhere in
between.
It works! Just don't get low, slow, and downwind.

After years as a glider-guider (or a "dope on a rope" if you prefer) I
have
finally taken up powered flight, and I am not at all sure that I have
truly
internalized the concept that go-arounds are now an option.

Vaughn

Don't forget and land that Cessna in the grass alongside the runway. It's
REALLY hard to explain that.

BTW, A glider can do a LOT more than most people think. A pilot from Reno
flew non-stop to Steamboat Springs, Colorado last month - about 843nm.

A story.

Long ago I was entering the pattern with a sailplane at a one runway tower
controlled airport in Texas. While I was on downwind, a Piper blew a tire
on the runway, blocking it. The tower asked me nervously where I could
land. I had noticed that there was weak lift in the pattern so I replied,
"no problem, I can hold".

It took about 15 minutes to move the Piper clear of the active. Meantime, I
slowly and silently circled at 1000' AGL. Each time I came around, I could
see the faces of the tower personnel pressed against the glass watching me.

When the landing clearance came, I landed long, took a high speed exit that
led to the transit parking area and stopped on a tiedown. Some local folks
bought me dinner and beer that night while I waited for my crew. I think
there were a few new glider pilots that came out of that.

Bill Daniels

Not necessarily true, but also virtually never necessary. A good sailplane
gives you amazing glideslope control. With the spoilers fully deployed, I am
literally standing on the rudder pedals in some sailplanes approaching the
runway like a nicely controllable anvil; yet you can close them at any time to
instantly regain your full glide ratio, or modulate them anywhere in between.
It works! Just don't get low, slow, and downwind.

After years as a glider-guider (or a "dope on a rope" if you prefer) I have
finally taken up powered flight, and I am not at all sure that I have truly
internalized the concept that go-arounds are now an option.

Wolfgang pointed out in the 1940s that most lightplanes suffered not
from too poor a glide ratio but one that was too good-making power off
approaches challenging when it has to be done for real.

Most any airplane can be deadsticked-it was done with the F-104
several times, the most famous being the RCAF pilot who executed a
perfect rollout in the middle of a huge frozen lake, rolled to a stop,
got out-then panicked at being on the ice alone,climbed back in the
cockpit and shot himself dead. (The airplane was fixed and flown out.)
The X-1, X-15, and other rocket planes landed deadstick every time and
so does the Space Shuttle.

(Exception-the T-38 and a couple other jet twins with irreversible
hydraulic flight controls and no RAT or standby electric or hydrazine
pump. The USAF justifies this by saying if both engines quit we want
the pilots to punch out,it's safer.)

Today, light planes-particularly the ones that crash with six people
and get the manufacturer sued-are always flown with power-on
approaches so the obsolete museum piece forward of the firewall
doesn't get shock cooled. Then said museum piece quits.... This is an
example of "organized stupidity". An effective speedbrake/spoiler
system would have prevented, in my opinion and in that of many more
well qualified people than myself, the majority of fatal Bonanza
crashes in the last 40 years.

Has experimental aviation learned from this? Well, not yet, but
there's still hope.

(Jim-Ed Browne) wrote in message . com...

Today, light planes-particularly the ones that crash with six people
and get the manufacturer sued-are always flown with power-on
approaches _so the obsolete museum piece forward of the firewall
doesn't get shock cooled_. Then said museum piece quits.... This is an
example of "organized stupidity". An effective speedbrake/spoiler
system would have prevented, in my opinion and in that of many more
well qualified people than myself, the majority of fatal Bonanza
crashes in the last 40 years.

Mr. Jimed...I suspect that you are merely a troll, and to those on rah
who have been ignoring you, I apologize. On the other hand, this post
represents an abysmal lack of knowledge and requires comment.

Specifically, I would like to point out that your claim that power-on
approaches are "so (the tried and true aircraft engine) forward of the
firewall doesn't get shock cooled..." is patently absurd. Power-on
landings are used to control the descent rate of the airplane...or to
remove the far too effective drag device of the windmilling propeller
(as in my RV-8A)...or for other reasons, but certainly not to prevent
shock-cooling. The minimal application of the throttle needed would
not be accomplish that goal, firstly, and secondly, the time for that
is long past on landing approach.

I have little doubt that this represents a precis' of your entire
knowledge base regarding things aeronautical, and with that, am done
with you.

Jim
RV-8A N888FP