Have you guys ever noticed the void?

I look at all the plans on offer for building aircraft and not one of
them ever includes any of the structural calculations.

Dont you guys ever feel totally unnerved by the fact that you have no
real idea of just where the strengths and weaknesses lie in a design?

If you cock up something during construction and you need to work out
whether it will be strong enough to carry the loads in spite of the
mistake how on earth do you make a sensible informed decision?

I never fail to be amazed that the absence of key information
verifying the structural integrity of a design is never seen as a
problem.
methinks it would make a really good EAA initiative for the second
century of aviation to start educating people to make available their
structural calcs.

Stealth(its a world wide void) Pilot

Stealth Pilot wrote:

Dont you guys ever feel totally unnerved by the fact that you have no
real idea of just where the strengths and weaknesses lie in a design?

------------------------------------------------------------------------------

So fill the void yourself. Slide rule, #2 yaller pencil and the back
of an envelop, you're half way there. (You may use a calculator, if
you wish.)

The other half has to do with the basic purpose of the 'Experimental -
Amateur Built' licensing category, in that it exists to foster
aeronautical education, which implies the need to know what you're
doing, if not from the outset, at least before first-flight.

And if that sounds slightly fey, as I'm sure it will to most of the
kit-assemblers, consider the other side of the coin: If the designer
provided you with detailed data, how would you know they were correct
without duplicating his calculations? Even then, weight -- that is,
ACTUAL weight -- is a critical factor in those calculations. A lot of
home-builts were designed by midgets for others of their kind and often
cite weights and g-factors that are wildly fallacious if not out-right
lies. Stuff a two hundred fifty pound lard-ass in the cockpit, use
real numbers and the calculations for some of the most popular designs
are liable to read 'Lawn Dart.'

Expecting the EAA to do something about your 'void' is wishful
thinking, in my opinion. Based on the advertisements and informercials
in their magazines, the EAA has no qualms about accepting money from
hucksters offering you everything from flying saucers to engines that
will rust out before they wear out.

I suggest the wiser course is to think for yourself If that requires
cracking a few books on airframe structural analysis, so be it. (Try a
search using 'fundamentals of aircraft structural analysis.' The books
are out there and fairly cheap, too -- apparently because nobody reads
them :-)

-R.S.Hoover

I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot. Most every calculation I need to make comes from an average, if
not a guess.

I did some basic calculations on the wing used on the Chuckbird/Texas
Parasol
before building my first one. I came up with a shade over 4 G's at 650
pounds.
(seemed like a good idea before selling plans)

Then got Nuked by several guys who claimed the wing was "weak" - because
they
were building 650 pounds - EMPTY.(and it was my fault!?!)

E-bleepin'-nough!

Richard

Lou wrote:

I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot. Most every calculation I need to make comes from an average, if
not a guess.

On Mon, 09 Jan 2006 22:13:59 GMT, Richard Lamb
wrote:

I did some basic calculations on the wing used on the Chuckbird/Texas
Parasol
before building my first one. I came up with a shade over 4 G's at 650
pounds.
(seemed like a good idea before selling plans)

Then got Nuked by several guys who claimed the wing was "weak" - because
they
were building 650 pounds - EMPTY.(and it was my fault!?!)

E-bleepin'-nough!

Richard

wings should have a 1.5 margin of safety so if your wing is 4g's at
650 lbs ultimate strength then you actually designed a 2.6g working
strength wing at that weight.
2.6 x 1.5 = 4

you make my point exactly. by publishing your figures others who are
interested can check your numbers and point out errors that you might
have missed.
60 degree banked turns would be ok but steepen up the bank angle a
little, hit some turbulence, .... poof, tinsel time.

got a sweat up? :-)


look at the rest of usenet. if you made an honest effort and stuffed
up someone would almost certainly post details of a more suitable
design.

I think that this is an area that we enthusiasts should be devoting
some attention to in the future.
Stealth Pilot

No sweat, just a basic misunderstanding.

We design to a 4 G _yiield_ limit.

This is where the wing, after being stressed, no longer
returns to the original shape
It has reached the "plastic" limit and has deformed.
Yes, it has failed, but it did not break.

The 1.5 G safety factor then gives a 6 G _ultimate_ limit.
THIS is where the wing breaks.

mo better?

Richard

On 9 Jan 2006 12:16:29 -0800, "Lou" wrote:

I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot.

Which is probably one reasons designers don't provide the equations. Many hate
it when folks make changes.

Ron Wanttaja

Ron Wanttaja wrote:
On 9 Jan 2006 12:16:29 -0800, "Lou" wrote:


I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot.


Which is probably one reasons designers don't provide the equations. Many hate
it when folks make changes.

Ron Wanttaja


especially when they then use the SAME name for the aircraft...

John

Ron Wanttaja wrote:
On 9 Jan 2006 12:16:29 -0800, "Lou" wrote:


I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot.


Which is probably one reasons designers don't provide the equations. Many hate
it when folks make changes.

Most equations for light airplane design are well established and have
been around for decades. What unique equations could a typical designer
provide?

Matt

Matt Whiting wrote:

Ron Wanttaja wrote:
On 9 Jan 2006 12:16:29 -0800, "Lou" wrote:


I have to admit he does bring up a good point. I have often wondered
what the difference in strength's and weakness would be if I used
different wood in my plane, or enlarged the components for a larger
pilot.


Which is probably one reasons designers don't provide the equations. Many hate
it when folks make changes.

Most equations for light airplane design are well established and have
been around for decades. What unique equations could a typical designer
provide?

Matt

Bless you pilgrim, for you are wise beyond your years.