On Sun, 18 Sep 2005 23:37:30 -0400, "Gordon Arnaut"
wrote:

Evan,

I don't want to drag this out, I think some good points ahve been made --
however, I don't see why fiberglass airframe construction is going to be
less labor-intensive.

Once you have the moulds constructed, fiberglass lends itself well to
making large compound structures as one piece.

There is almost zero opportunity for automation in fiberglass construction,

That depends on your thinking. Fiberglass composite also lends
itself well to putting pieces together.

unless you go to specialized processes and tooling that are probably out of
reach for a small firm. Even Cirrus and Adam do a lot of their layups by
hand -- granted using pre-pregs.

Now look at a simple little plane like the Zenith 601. They used to build
one of these in a week at Oshkosh, using volunteers from the crowd. It uses
pull-type rivets rather than bucked, so the structure can be assembled quite
quickly. I think the total time to get to the flying plane was about 300 man
hours.

And I don't think the Zenith kit parts are as automated as they could be --
for instance I don't the they are fully precut and pre-punched etc. like the
Van's kits.

My point is that if you purpose-designed a small aluminum airplane for quick
construction and automated the sheet-metal stamping part of the process, you
could make that airplane very cost-effectively.

Perhaps a fiberglass approach could work just as well, but I think more
ingenuity would be required.

It would and it would.

However, in the case of the sport plane specifications, the plane
could be constructed of shells that could be fastened together.
They could be composite shells, with the joggle and two aluminum
strips where they would be pop riveted together with cherry max
rivets.

After all they do not under go any where near the stress of a Cirrus,
Lancair, or Glasair III. Staying within those specs makes both the
metal and composite structures much more simple. OTOH you still have
all the insurance costs.

If and I emphasize the IF the market were there to justify true mass
production then airframes, engines and basic avionics could be
produced at considerably less. If you could sell even 20,000 small
displacement engines like the Jabaru they'd become *relatively* less
expensive compared to now.

Let's face it, even at Cessna's best year, that was a specialized
market and peanuts compared to the automobile.

However, first you have to have the market. You aren't going to do a
lot of high profile advertising for a nitch market that may develop.
Once the potential market is there the advertising can increase, and
production will follow.

It's much like the chicken or the egg. The market has to develop
slowly. The faster it develops the more sensitive it is to upsets.

However, I seriously doubt that we will ever see more than about three
times the number of planes currently flying. Beyond that we'd need a
complete now traffic system even if most of it is local.

Roger Halstead (K8RI & ARRL life member)
(N833R, S# CD-2 Worlds oldest Debonair)
www.rogerhalstead.com



Regards,

Gordon.




"Evan Carew" wrote in message
. ..
Gordon,

Unfortunately, I have to disagree with you on your analysis of aluminum
use in commercially built LSA aircraft structures. While it is true that
the aluminum materials costs for an aircraft are lower, the labor costs
(which I have already shown to be the largest cost in building any plane)
are much higher, thus making it a poor choice if you are trying to build
such airplanes for a profit. On the other hand, if you are trying to sell
kit LSA airframes, then the builder assumes the labor costs, thus making a
comparable kit seem less expensive.