motorgliders as towplanes

On Mar 20, 4:58*pm, Doug Hoffman wrote:
Bob Kuykendall wrote:
On Mar 19, 6:08 pm, Doug Hoffman wrote:

I just wish the US would perform its conversion to metric units for
*everything*. *The sooner the better. *But that job is being handled by
our highly efficient government. *Don't hold your breath. *:-)

Kind of a hijack, but what I wish is that aircraft hardware
manufacturers would get their crap together and produce a coherent
metric equivalent of the AN system of common aircraft hardware.

The magic of the AN hardware system is not that they offer any
particularly high strength (they don't; for the most part AN bolts are
equivalent to Grade 5 hardware store bolts) or any particularly high
precision (again, they're about the same as the bolts at Ace or True
Value). The magic is that AN bolts have just enough thread for a nut
and somewhere between 0" and about 0.125" of washers, and that they
come in length increments of 0.125". Those two elements let you create
a nice, tidy bolted joint of virtually any practical grip length, and
not have the threaded portion of the bolt loaded in shear, and not
have a bunch of threads hanging out of the nut. Furthermore, common AN
hardware is very attractively priced, for the most part you can buy
them from any of several aircraft parts outlets at the same or even
lower prices as Grade 5 bolts at a mom&pop hardware store.

By contrast, metric aircraft hardware has no coherent system of
markings, thread lengths, and grip lengths. It averages twice or
thrice the cost of AN hardware when you can find it, and is available
from only a few outlets. When you need a replacement bolt for your
European aircraft, you have virtually no choice but to order it
directly from the manufacturer at huge markups and with huge shipping
charges.

I like the metric system, and I like metric hardware. I appreciate
that even American cars are, by and large, assembled with metric nuts
and bolts these days. But given the choice between about $500 worth of
AN hardware per aircraft and twice or thrice that in metric nuts and
bolts that offer no greater utility, hmmm, I think I'll go with the
less expensive option.

End rant.

Hi Bob,

Yes. *There may be some niche areas like aircraft hardware that would at
least require legacy support for a period of years. *Makes me wonder
what Boeing/Cessna and others are doing now and plan to do in the future
in that respect.

Regards,

-Doug

Btw, American designed cars and trucks do more than just assemble with
metric fasteners. *Nominal dimensions are typically, e.g., 100 mm for a
bracket width instead of 4.0". *We call that "hard metric" design. *Some
user interface items like wheel lug nuts may still be SAE.- Hide quoted text -

- Show quoted text -

While we're 'Ranting'.... Bob, that would be nice, wouldn't it? It
took me 2 tries to get the right bolt from Grob when I went throught
my control system a few years ago.
DON'T get me started on US auto makers. I have two Dodge Trucks. I
HATE the fact that evey time I get under one to work on it, I need to
take BOTH metric and SAE tools. Pick a STANDARD! My favorite example
was an exhaust stud on a 1998 Olds Intrigue. Engine side - SAE
exhaust flange side - metric.
Rant off.
I feel better now.

On 21 Mar, 03:17, Uncle Fuzzy wrote:

While we're 'Ranting'.... Bob, that would be nice, wouldn't it? *It
took me 2 tries to get the right bolt from Grob when I went throught
my control system a few years ago.

You think that;s bad? Try getting specialist fasteners for old Polish
gliders. Or, on the ground, getting fasteners in the odd 5mm-but-not-
M5 thread that Citroen used. I've seen refurbished original Citroen
nuts and bolts at €4 per item - not per set!

Ian

At 11:44 21 March 2009, The Real Doctor wrote:

You think that;s bad? Try getting specialist fasteners for old Polish
gliders. Or, on the ground, getting fasteners in the odd 5mm-but-not-
M5 thread that Citroen used. I've seen refurbished original Citroen
nuts and bolts at =804 per item - not per set!

I have to keep my Whitworth wrenches on hand when working on my
Austin-Healey 100. Some of the basic stuff that came out of the parts
bins, like suspension and transmission, uses Whitworth hardware, while the
rest works with SAE stuff. It's still possible to buy Whitworth threaded
fasteners, but you have to know where to look. Are there any British
gliders left that are old enough to have used Whitworth hardware?

Jim Beckman

On 21 Mar, 13:30, Jim Beckman wrote:

*Are there any British
gliders left that are old enough to have used Whitworth hardware?

The UK car industry switched over to UNF/UNC in the early sixties, but
I wouldn'r be suprised to find Whitworth/BSF in anything Slingsby made
until the late 60's. They were masters of improvisation ... for many
years Slingsby glider main wheels were surplus Spitfire tailwheels.

I have to keep a full set of imperial tools for my Herald and a full
set of metric ones for my DS. I still have a Whitworth set from when I
had a 1959 Morris Minor but it doesn;t get much use. The Micra just
never needs mending, so nut sizes are irrelevant ...

Ian

On Mar 20, 8:17*pm, Uncle Fuzzy wrote:
...My favorite example was an exhaust stud on a 1998 Olds
Intrigue. *Engine side - SAE exhaust flange side - metric.

SAE and metric threads on the same stud? Yup, that's odd all right.

My favorite example of transitional hardware is the Volvo 240 series.
You'd find SAE hardware on anything it inherited from the 140 series
(most bodywork, a lot of the driveline) and metric on anything
introduced new with the 240 (B21 or later engine, M41 or M46
transmission, MacPhereson strut front suspension).

Thanks, Bob K.

On 21 Mar, 15:19, Bob Kuykendall wrote:
On Mar 20, 8:17*pm, Uncle Fuzzy wrote:

...My favorite example was an exhaust stud on a 1998 Olds
Intrigue. *Engine side - SAE exhaust flange side - metric.

SAE and metric threads on the same stud? Yup, that's odd all right.

My friendly local tool shop used to sell UNF/UNC nuts and bolts ...
with metric heads. Confused the hell out of me when I had to replace
some of them years later.

Ian

UF

Don't bitch.The P-51, with Merlin engine, had one set of tools for
engine and another set for airplane. That was back in 40's (WWII) )
Crew chief carried two bags when he went to work on bird.

Have a nice Day.

Big John



On Fri, 20 Mar 2009 20:17:15 -0700 (PDT), Uncle Fuzzy
wrote:

On Mar 20, 4:58*pm, Doug Hoffman wrote:
Bob Kuykendall wrote:
On Mar 19, 6:08 pm, Doug Hoffman wrote:

I just wish the US would perform its conversion to metric units for
*everything*. *The sooner the better. *But that job is being handled by
our highly efficient government. *Don't hold your breath. *:-)

Kind of a hijack, but what I wish is that aircraft hardware
manufacturers would get their crap together and produce a coherent
metric equivalent of the AN system of common aircraft hardware.

The magic of the AN hardware system is not that they offer any
particularly high strength (they don't; for the most part AN bolts are
equivalent to Grade 5 hardware store bolts) or any particularly high
precision (again, they're about the same as the bolts at Ace or True
Value). The magic is that AN bolts have just enough thread for a nut
and somewhere between 0" and about 0.125" of washers, and that they
come in length increments of 0.125". Those two elements let you create
a nice, tidy bolted joint of virtually any practical grip length, and
not have the threaded portion of the bolt loaded in shear, and not
have a bunch of threads hanging out of the nut. Furthermore, common AN
hardware is very attractively priced, for the most part you can buy
them from any of several aircraft parts outlets at the same or even
lower prices as Grade 5 bolts at a mom&pop hardware store.

By contrast, metric aircraft hardware has no coherent system of
markings, thread lengths, and grip lengths. It averages twice or
thrice the cost of AN hardware when you can find it, and is available
from only a few outlets. When you need a replacement bolt for your
European aircraft, you have virtually no choice but to order it
directly from the manufacturer at huge markups and with huge shipping
charges.

I like the metric system, and I like metric hardware. I appreciate
that even American cars are, by and large, assembled with metric nuts
and bolts these days. But given the choice between about $500 worth of
AN hardware per aircraft and twice or thrice that in metric nuts and
bolts that offer no greater utility, hmmm, I think I'll go with the
less expensive option.

End rant.

Hi Bob,

Yes. *There may be some niche areas like aircraft hardware that would at
least require legacy support for a period of years. *Makes me wonder
what Boeing/Cessna and others are doing now and plan to do in the future
in that respect.

Regards,

-Doug

Btw, American designed cars and trucks do more than just assemble with
metric fasteners. *Nominal dimensions are typically, e.g., 100 mm for a
bracket width instead of 4.0". *We call that "hard metric" design. *Some
user interface items like wheel lug nuts may still be SAE.- Hide quoted text -

- Show quoted text -

While we're 'Ranting'.... Bob, that would be nice, wouldn't it? It
took me 2 tries to get the right bolt from Grob when I went throught
my control system a few years ago.
DON'T get me started on US auto makers. I have two Dodge Trucks. I
HATE the fact that evey time I get under one to work on it, I need to
take BOTH metric and SAE tools. Pick a STANDARD! My favorite example
was an exhaust stud on a 1998 Olds Intrigue. Engine side - SAE
exhaust flange side - metric.
Rant off.
I feel better now.

On 21 Mar, 23:35, Tech Support wrote:

Don't bitch.The P-51, with Merlin engine, had one set of tools for
engine and another set for airplane. That was back in 40's (WWII) )
Crew chief carried two bags when he went to work on bird.

The Citroen 2CV came with two (I think, may have been three) spanners
which allowed you to do anything up to and including a full engine
rebuild.

Ian

On Mar 21, 7:12*pm, The Real Doctor wrote:
On 21 Mar, 23:35, Tech Support wrote:

Don't bitch.The P-51, with Merlin engine, had one set of tools for
engine and another set for airplane. That was back in 40's (WWII) )
Crew chief carried two bags when he went to work on bird.

The Citroen 2CV came with two (I think, may have been three) spanners
which allowed you to do anything up to and including a full engine
rebuild.

Ian
The P-51, however, at least had the excuse of being a wartime
project. GM, Chrysler, and (I assume) other US automakers don't have
that going for them. They really do need to pick a standard and stick
with it.
.... and I can do everything short of a bottom end rebuild or tranny
rebuild on my 36 year old BMW motorcycle with the tools in the stock
tool kit plus a torque wrench.