Flying on the Cheap - Wood

To All:

A few years ago I posted an article offering some hints about how to
build an inexpensive airplane that was safe and reliable (Flying on the
Cheap, October 2001; Google will find it for you). The key point in
the article was the use of commonly available mild steel tubing for the
fuselage. Of course, that meant you had to weld and nowadays most
folks don't, nor do they want to learn. Wood's the thing,
according to non-welding folks, citing its use in KR's and Piets and
dozens of other airframes, each held as the Perfect Design by that
particular person.

The advocates of wooden airframe construction have a valid point, at
least here in the States. Because of the rise of the box stores (Home
Depot, Lowes, etc), wood is more commonly available than steel tubing
and despite what many think, there's plenty of aviation-quality wood
lurking inside the knot-hole collection at your local box store. The
task of the lo-buck builder is to cut away the non-aviation parts, glue
the good stuff together and go flying. Thanks to modern adhesives, the
likelihood of a novice builder producing an unsafe glue-joint is small.


To support the builders of Box Store Bombers I shared my woodworking
experience in several articles posted to this newsgroup (How to Make
Ribs Out of Old Orange Crates [Nov 2002], Wooden Notes [Jan 2006] and
several others). Surprisingly, homebuilding at that level is not an
especially welcome topic on the rec.aviation.homebuilt newsgroup. This
lead to relaying such information in private posts to guys who were
interested in actually building something. Like Fred. Which isn't
his name, but work with me here.

After considerable thought Fred settled upon a single-place, VW-powered
KR-ish design as being the best match for his particular situation. In
working toward that goal he didn't find much support, especially from
the only organization that claims to speak for grass-roots aviation in
America. Thanks to an income of only $25k or thereabouts, to the EAA,
Fred and the millions of people like him simply do not exist. But Fred
is determined to build and fly his very own airplane, even if he has to
use the local box store for most of his materials. Indeed, he
doesn't have much choice. The total cost for his box store lumber
will be under $100 whereas a kit of aviation-grade spruce would cost
about a thousand dollars by the time the freight was paid. The lumber
will have to be resawn and spliced but that's the reality of Flying
on the Cheap.

Fred is bucking additional headwinds in that he has zero woodworking
experience, doesn't own a table saw and has only a limited amount of
shop space. But he does have a computer and lots of determination.
With a bit of help, he has been making slow but steady progress.

Having finally gained access to a table saw, Fred began prowling the
box stores for suitable lumber. (His KR-ish design uses built-up
spars, the main spar having caps two inches square, the aft spar about
an inch.) His next message verged on panic. Did I know that ALL of
the lumber sold in box stores was incorrectly marked? Some of their
one inch wood was only three-quarters of an inch thick! And all of the
2x4's he looked at were only one and a half by three and a half!

I assured Fred that the box stores weren't trying to cheat him,
explained about rough versus finished dimensions and pointed him toward
some places on the internet where the matter was explained in more
detail. His reply sounded a bit discouraged, having realized he
won't be able to cut a 2x2 out of any piece of finish-size
two-by-something lumber. The only way he's going to get a good 2x2
stick is to start with 1x2's, spliced to get rid of any knots, and
glue them together to get his 2x2's. That's the reality of Flying
on the Cheap (why does that sound familiar...) but as a matter of fact,
except for the splices it isn't that much different than starting
with a spruce kit.

I sent him some drawings showing how to slice up a 2x4 to produce spar
caps. Because of the knots he'll probably need about eighteen
2x4's, resawn and laminated to produce the required number of spar
caps. It is labor intensive but there's surprisingly little waste
since the residue of spar cap production yields the intercostals,
stringers and tail-feather spars.

Any mention of splicing spars usually sets several heads of hair on
fire, even though such splices are an accepted practice, their details
fully covered in the old CAM or the new AC13 manuals. In fact, once
you've made up a suitable fixture to ensure all of your splices will
have the same angle, doing a long-splice in solid wood is no more
difficult than doing a short-splice in plywood. (Hint: Solid wood,
you want an angle of about 1:15. With plywood, thanks to the
orientation of the plys, you can develop full strength with angles
between 1:10 for mahogany and 1:12 for birch. As a point of interest,
boat builders commonly use 1:8 for either.)

Making up a scarfing fixture tends to drive a lot of homebuilders crazy
as they fiddle and tweak, trying to achieve a precise angle of 3.8
degrees for a long-splice. Or 7.1 degrees for a boat-work 1:8. The
truth is, the precise angle doesn't really matter. What matters is
that all of the pieces be cut to EXACTLY the SAME angle... and that the
splice be strong enough for the task at hand. This degree of accuracy
can be achieved using nothing more complicated than fixtures assembled
from scrap wood, one for scarfing solid stock, the other for scarfing
plywood. In each case the wood gets clamped in the fixture and the
same cutter - - a portable circular saw - - is used on both.

(As you might suspect, scarfing actually begins at the box store. When
picking the stack for lumber having the proper grain and run-out, you
envision the cuts you'll make when resawing. In many cases you can
orient the piece so that any knots fall entirely within the pieces you
are cutting off, leaving you with a knot-free stick.)

When using box store lumber for airplanes or boats there are a host of
details bobbing just beneath the surface, ready to sink the unwary.
Most of those details can be resolved with a dose of plain
old-fashioned Common Sense, such as keeping your saw-blades sharp,
adjusting the rate of your cut according to its depth and so forth.
Fortunately the details tend to be fail-safe. And self-educating
because of it. Do it wrong, you'll end up with a part that can't
be used. But once you get the hang of it, splicing longerons or spar
caps is no more complicated than checking the air in your tires.

- -

For more than fifteen years millions of low-income but air-minded
Americans waited for Light Sport Aircraft to become a reality. Sadly,
that reality is airplanes and flight training which remain too
expensive for the average American. As the LSA concept turned into
vapor-ware I began receiving more mail from people like Fred who have
decided to follow a different drummer. On the whole, I think this is a
good idea. Based on more than ten years of such messages, folks like
Fred cleave closer to the ideals of grass-roots aviation. These folks
have learned more about their engines and airframes than the typical
kit-builder and some have acquired a remarkable depth of knowledge in
engineering and aeronautics. But I don't think we'll see Fred at
Oshkosh - - it's simply gotten too expensive. Indeed, I've a hunch
a lot of these fellows will end up flying 'black' - - completely
off the books of any Agency or organization. Not because they want to
but because it's the only way they can keep the Dream alive.

-R.S.Hoover

More power to Fred... I hope he can stay the course and get a flying
machine...

denny

wrote:
To All:

A few years ago I posted an article offering some hints about how to
build an inexpensive airplane that was safe and reliable (Flying on the
Cheap, October 2001; Google will find it for you). The key point in
the article was the use of commonly available mild steel tubing for the
fuselage. Of course, that meant you had to weld and nowadays most
folks don't, nor do they want to learn. Wood's the thing,
according to non-welding folks, citing its use in KR's and Piets and
dozens of other airframes, each held as the Perfect Design by that
particular person.

The advocates of wooden airframe construction have a valid point, at
least here in the States. Because of the rise of the box stores (Home
Depot, Lowes, etc), wood is more commonly available than steel tubing
and despite what many think, there's plenty of aviation-quality wood
lurking inside the knot-hole collection at your local box store. The
task of the lo-buck builder is to cut away the non-aviation parts, glue
the good stuff together and go flying. Thanks to modern adhesives, the
likelihood of a novice builder producing an unsafe glue-joint is small.


To support the builders of Box Store Bombers I shared my woodworking
experience in several articles posted to this newsgroup (How to Make
Ribs Out of Old Orange Crates [Nov 2002], Wooden Notes [Jan 2006] and
several others). Surprisingly, homebuilding at that level is not an
especially welcome topic on the rec.aviation.homebuilt newsgroup. This
lead to relaying such information in private posts to guys who were
interested in actually building something. Like Fred. Which isn't
his name, but work with me here.

After considerable thought Fred settled upon a single-place, VW-powered
KR-ish design as being the best match for his particular situation. In
working toward that goal he didn't find much support, especially from
the only organization that claims to speak for grass-roots aviation in
America. Thanks to an income of only $25k or thereabouts, to the EAA,
Fred and the millions of people like him simply do not exist. But Fred
is determined to build and fly his very own airplane, even if he has to
use the local box store for most of his materials. Indeed, he
doesn't have much choice. The total cost for his box store lumber
will be under $100 whereas a kit of aviation-grade spruce would cost
about a thousand dollars by the time the freight was paid. The lumber
will have to be resawn and spliced but that's the reality of Flying
on the Cheap.


Aircraft wood doesn't necessarily have to come from Wicks or Aircraft
Spruce: it has to meet the requirements as set forth in AC 43-13 et
seq. You can find aircraft wood or get it sawn if you know what to look
for. But using wood that clearly is out of those spec is going to cause
trouble.

The biggest problem with flying costs are not traditional simple
airframes: they are the overpriced ridiculous powerplants and high
storage costs.

Direct drive VW made sense in 1965. Not today. Use a liquid cooled car
engine and a redrive, perhaps a Honda since they are attractively
priced as JDM pulls.

On 10 Aug 2006 05:23:38 -0700, "Bret Ludwig"
wrote:




Aircraft wood doesn't necessarily have to come from Wicks or Aircraft
Spruce: it has to meet the requirements as set forth in AC 43-13 et
seq. You can find aircraft wood or get it sawn if you know what to look
for. But using wood that clearly is out of those spec is going to cause
trouble.

wood is just an engineering material, one of many, it has to meet the
strength requirements put on it by the loads on the airframe.

ac43-13 contains a description of what woods that have met the
requirements usually look like. it is the structural characteristics
of the wood that are important not the visual appearance.

btw I agree totally with Veedubbers comments on wood sourcing and wood
selection. none of my wood comes from certified sources.

Stealth Pilot

wrote:
To All:

A few years ago I posted an article offering some hints about how to
build an inexpensive airplane that was safe and reliable (Flying on the
Cheap, October 2001; Google will find it for you). The key point in
the article was the use of commonly available mild steel tubing for the
fuselage. Of course, that meant you had to weld and nowadays most
folks don't, nor do they want to learn. Wood's the thing,
according to non-welding folks, citing its use in KR's and Piets and
dozens of other airframes, each held as the Perfect Design by that
particular person.

The advocates of wooden airframe construction have a valid point, at
least here in the States. Because of the rise of the box stores (Home
Depot, Lowes, etc), wood is more commonly available than steel tubing
and despite what many think, there's plenty of aviation-quality wood
lurking inside the knot-hole collection at your local box store. The
task of the lo-buck builder is to cut away the non-aviation parts, glue
the good stuff together and go flying. Thanks to modern adhesives, the
likelihood of a novice builder producing an unsafe glue-joint is small.


To support the builders of Box Store Bombers I shared my woodworking
experience in several articles posted to this newsgroup (How to Make
Ribs Out of Old Orange Crates [Nov 2002], Wooden Notes [Jan 2006] and
several others). Surprisingly, homebuilding at that level is not an
especially welcome topic on the rec.aviation.homebuilt newsgroup. This
lead to relaying such information in private posts to guys who were
interested in actually building something. Like Fred. Which isn't
his name, but work with me here.

After considerable thought Fred settled upon a single-place, VW-powered
KR-ish design as being the best match for his particular situation. In
working toward that goal he didn't find much support, especially from
the only organization that claims to speak for grass-roots aviation in
America. Thanks to an income of only $25k or thereabouts, to the EAA,
Fred and the millions of people like him simply do not exist. But Fred
is determined to build and fly his very own airplane, even if he has to
use the local box store for most of his materials. Indeed, he
doesn't have much choice. The total cost for his box store lumber
will be under $100 whereas a kit of aviation-grade spruce would cost
about a thousand dollars by the time the freight was paid. The lumber
will have to be resawn and spliced but that's the reality of Flying
on the Cheap.

Fred is bucking additional headwinds in that he has zero woodworking
experience, doesn't own a table saw and has only a limited amount of
shop space. But he does have a computer and lots of determination.
With a bit of help, he has been making slow but steady progress.

Having finally gained access to a table saw, Fred began prowling the
box stores for suitable lumber. (His KR-ish design uses built-up
spars, the main spar having caps two inches square, the aft spar about
an inch.) His next message verged on panic. Did I know that ALL of
the lumber sold in box stores was incorrectly marked? Some of their
one inch wood was only three-quarters of an inch thick! And all of the
2x4's he looked at were only one and a half by three and a half!

I assured Fred that the box stores weren't trying to cheat him,
explained about rough versus finished dimensions and pointed him toward
some places on the internet where the matter was explained in more
detail. His reply sounded a bit discouraged, having realized he
won't be able to cut a 2x2 out of any piece of finish-size
two-by-something lumber. The only way he's going to get a good 2x2
stick is to start with 1x2's, spliced to get rid of any knots, and
glue them together to get his 2x2's. That's the reality of Flying
on the Cheap (why does that sound familiar...) but as a matter of fact,
except for the splices it isn't that much different than starting
with a spruce kit.

I sent him some drawings showing how to slice up a 2x4 to produce spar
caps. Because of the knots he'll probably need about eighteen
2x4's, resawn and laminated to produce the required number of spar
caps. It is labor intensive but there's surprisingly little waste
since the residue of spar cap production yields the intercostals,
stringers and tail-feather spars.

Any mention of splicing spars usually sets several heads of hair on
fire, even though such splices are an accepted practice, their details
fully covered in the old CAM or the new AC13 manuals. In fact, once
you've made up a suitable fixture to ensure all of your splices will
have the same angle, doing a long-splice in solid wood is no more
difficult than doing a short-splice in plywood. (Hint: Solid wood,
you want an angle of about 1:15. With plywood, thanks to the
orientation of the plys, you can develop full strength with angles
between 1:10 for mahogany and 1:12 for birch. As a point of interest,
boat builders commonly use 1:8 for either.)

Making up a scarfing fixture tends to drive a lot of homebuilders crazy
as they fiddle and tweak, trying to achieve a precise angle of 3.8
degrees for a long-splice. Or 7.1 degrees for a boat-work 1:8. The
truth is, the precise angle doesn't really matter. What matters is
that all of the pieces be cut to EXACTLY the SAME angle... and that the
splice be strong enough for the task at hand. This degree of accuracy
can be achieved using nothing more complicated than fixtures assembled
from scrap wood, one for scarfing solid stock, the other for scarfing
plywood. In each case the wood gets clamped in the fixture and the
same cutter - - a portable circular saw - - is used on both.

(As you might suspect, scarfing actually begins at the box store. When
picking the stack for lumber having the proper grain and run-out, you
envision the cuts you'll make when resawing. In many cases you can
orient the piece so that any knots fall entirely within the pieces you
are cutting off, leaving you with a knot-free stick.)

When using box store lumber for airplanes or boats there are a host of
details bobbing just beneath the surface, ready to sink the unwary.
Most of those details can be resolved with a dose of plain
old-fashioned Common Sense, such as keeping your saw-blades sharp,
adjusting the rate of your cut according to its depth and so forth.
Fortunately the details tend to be fail-safe. And self-educating
because of it. Do it wrong, you'll end up with a part that can't
be used. But once you get the hang of it, splicing longerons or spar
caps is no more complicated than checking the air in your tires.

- -

For more than fifteen years millions of low-income but air-minded
Americans waited for Light Sport Aircraft to become a reality. Sadly,
that reality is airplanes and flight training which remain too
expensive for the average American. As the LSA concept turned into
vapor-ware I began receiving more mail from people like Fred who have
decided to follow a different drummer. On the whole, I think this is a
good idea. Based on more than ten years of such messages, folks like
Fred cleave closer to the ideals of grass-roots aviation. These folks
have learned more about their engines and airframes than the typical
kit-builder and some have acquired a remarkable depth of knowledge in
engineering and aeronautics. But I don't think we'll see Fred at
Oshkosh - - it's simply gotten too expensive. Indeed, I've a hunch
a lot of these fellows will end up flying 'black' - - completely
off the books of any Agency or organization. Not because they want to
but because it's the only way they can keep the Dream alive.

-R.S.Hoover

If Fred plans to build a plane from wood purchased from Home Depot, he
should also build a pine box. He will need it. I have never found
wood acceptable for aircraft at HD or any other such outlet. Why pass
on such bad information?

There is another spec for Spruce and Doug Fir that is a bit easier to find
than "Spar Stock".
History lesson follows.... One of the biggest markets for dead straight
tight grain wood was for
the construction of fire department ladders, especially aerial ladders. The
ladder makers
created a standard for wood used in ladders. "Ladder Grade" spruce is a
commercial spec that is
indistinguishable from AC43 and in many cases tighter.. If you call around
and find the folks who sell it, you can save
hours of dumpster diving to find good stuff at box stores. It is reasonably
priced compared
to "airplans stuff" with only a moderate premium over regular wood prices.
Scott
"

pbc76049 (removethis) wrote:
There is another spec for Spruce and Doug Fir that is a bit easier to find
than "Spar Stock".
History lesson follows.... One of the biggest markets for dead straight
tight grain wood was for
the construction of fire department ladders, especially aerial ladders. The
ladder makers
created a standard for wood used in ladders. "Ladder Grade" spruce is a
commercial spec that is
indistinguishable from AC43 and in many cases tighter.. If you call around
and find the folks who sell it, you can save
hours of dumpster diving to find good stuff at box stores. It is reasonably
priced compared
to "airplans stuff" with only a moderate premium over regular wood prices.
Scott


If one is going to build anything of wood one needs to learn a great
deal about wood, at least in comparison to what most vendors know.
Dealing directly with mills is always advantageous, especially if you
are not in immediate need of the wood and can buy early and age it
yourself, at least partially. If you are contemplating building a
woodster, car, boat or plane, buy wood now and put it away. You can
always resell at no loss if you buy right.

"David Melby Cavalier" wrote in message
oups.com...

wrote:
To All:

A few years ago I posted an article offering some hints about how to
build an inexpensive airplane that was safe and reliable (Flying on the
Cheap, October 2001; Google will find it for you). The key point in
the article was the use of commonly available mild steel tubing for the
fuselage. Of course, that meant you had to weld and nowadays most
folks don't, nor do they want to learn. Wood's the thing,
according to non-welding folks, citing its use in KR's and Piets and
dozens of other airframes, each held as the Perfect Design by that
particular person.

The advocates of wooden airframe construction have a valid point, at
least here in the States. Because of the rise of the box stores (Home
Depot, Lowes, etc), wood is more commonly available than steel tubing
and despite what many think, there's plenty of aviation-quality wood
lurking inside the knot-hole collection at your local box store. The
task of the lo-buck builder is to cut away the non-aviation parts, glue
the good stuff together and go flying. Thanks to modern adhesives, the
likelihood of a novice builder producing an unsafe glue-joint is small.


To support the builders of Box Store Bombers I shared my woodworking
experience in several articles posted to this newsgroup (How to Make
Ribs Out of Old Orange Crates [Nov 2002], Wooden Notes [Jan 2006] and
several others). Surprisingly, homebuilding at that level is not an
especially welcome topic on the rec.aviation.homebuilt newsgroup. This
lead to relaying such information in private posts to guys who were
interested in actually building something. Like Fred. Which isn't
his name, but work with me here.

After considerable thought Fred settled upon a single-place, VW-powered
KR-ish design as being the best match for his particular situation. In
working toward that goal he didn't find much support, especially from
the only organization that claims to speak for grass-roots aviation in
America. Thanks to an income of only $25k or thereabouts, to the EAA,
Fred and the millions of people like him simply do not exist. But Fred
is determined to build and fly his very own airplane, even if he has to
use the local box store for most of his materials. Indeed, he
doesn't have much choice. The total cost for his box store lumber
will be under $100 whereas a kit of aviation-grade spruce would cost
about a thousand dollars by the time the freight was paid. The lumber
will have to be resawn and spliced but that's the reality of Flying
on the Cheap.

Fred is bucking additional headwinds in that he has zero woodworking
experience, doesn't own a table saw and has only a limited amount of
shop space. But he does have a computer and lots of determination.
With a bit of help, he has been making slow but steady progress.

Having finally gained access to a table saw, Fred began prowling the
box stores for suitable lumber. (His KR-ish design uses built-up
spars, the main spar having caps two inches square, the aft spar about
an inch.) His next message verged on panic. Did I know that ALL of
the lumber sold in box stores was incorrectly marked? Some of their
one inch wood was only three-quarters of an inch thick! And all of the
2x4's he looked at were only one and a half by three and a half!

I assured Fred that the box stores weren't trying to cheat him,
explained about rough versus finished dimensions and pointed him toward
some places on the internet where the matter was explained in more
detail. His reply sounded a bit discouraged, having realized he
won't be able to cut a 2x2 out of any piece of finish-size
two-by-something lumber. The only way he's going to get a good 2x2
stick is to start with 1x2's, spliced to get rid of any knots, and
glue them together to get his 2x2's. That's the reality of Flying
on the Cheap (why does that sound familiar...) but as a matter of fact,
except for the splices it isn't that much different than starting
with a spruce kit.

I sent him some drawings showing how to slice up a 2x4 to produce spar
caps. Because of the knots he'll probably need about eighteen
2x4's, resawn and laminated to produce the required number of spar
caps. It is labor intensive but there's surprisingly little waste
since the residue of spar cap production yields the intercostals,
stringers and tail-feather spars.

Any mention of splicing spars usually sets several heads of hair on
fire, even though such splices are an accepted practice, their details
fully covered in the old CAM or the new AC13 manuals. In fact, once
you've made up a suitable fixture to ensure all of your splices will
have the same angle, doing a long-splice in solid wood is no more
difficult than doing a short-splice in plywood. (Hint: Solid wood,
you want an angle of about 1:15. With plywood, thanks to the
orientation of the plys, you can develop full strength with angles
between 1:10 for mahogany and 1:12 for birch. As a point of interest,
boat builders commonly use 1:8 for either.)

Making up a scarfing fixture tends to drive a lot of homebuilders crazy
as they fiddle and tweak, trying to achieve a precise angle of 3.8
degrees for a long-splice. Or 7.1 degrees for a boat-work 1:8. The
truth is, the precise angle doesn't really matter. What matters is
that all of the pieces be cut to EXACTLY the SAME angle... and that the
splice be strong enough for the task at hand. This degree of accuracy
can be achieved using nothing more complicated than fixtures assembled
from scrap wood, one for scarfing solid stock, the other for scarfing
plywood. In each case the wood gets clamped in the fixture and the
same cutter - - a portable circular saw - - is used on both.

(As you might suspect, scarfing actually begins at the box store. When
picking the stack for lumber having the proper grain and run-out, you
envision the cuts you'll make when resawing. In many cases you can
orient the piece so that any knots fall entirely within the pieces you
are cutting off, leaving you with a knot-free stick.)

When using box store lumber for airplanes or boats there are a host of
details bobbing just beneath the surface, ready to sink the unwary.
Most of those details can be resolved with a dose of plain
old-fashioned Common Sense, such as keeping your saw-blades sharp,
adjusting the rate of your cut according to its depth and so forth.
Fortunately the details tend to be fail-safe. And self-educating
because of it. Do it wrong, you'll end up with a part that can't
be used. But once you get the hang of it, splicing longerons or spar
caps is no more complicated than checking the air in your tires.

- -

For more than fifteen years millions of low-income but air-minded
Americans waited for Light Sport Aircraft to become a reality. Sadly,
that reality is airplanes and flight training which remain too
expensive for the average American. As the LSA concept turned into
vapor-ware I began receiving more mail from people like Fred who have
decided to follow a different drummer. On the whole, I think this is a
good idea. Based on more than ten years of such messages, folks like
Fred cleave closer to the ideals of grass-roots aviation. These folks
have learned more about their engines and airframes than the typical
kit-builder and some have acquired a remarkable depth of knowledge in
engineering and aeronautics. But I don't think we'll see Fred at
Oshkosh - - it's simply gotten too expensive. Indeed, I've a hunch
a lot of these fellows will end up flying 'black' - - completely
off the books of any Agency or organization. Not because they want to
but because it's the only way they can keep the Dream alive.

-R.S.Hoover

If Fred plans to build a plane from wood purchased from Home Depot, he
should also build a pine box. He will need it. I have never found
wood acceptable for aircraft at HD or any other such outlet. Why pass
on such bad information?

Since Veeduber's original post, I have taken a long glance at the lumber in
both of the local big boxes, as well as a couple of the local independents,
and I have concluded that the method is reasonable and a good compromise.
Arguments in favor include:
1) the high cost of shipping for small quantities,
2) the ability to buy a little at a time
(think empenage kit, wing kit, etc.),
3) laminating can be used to defeat any remaining tendency of wood to warp
or bow over time,
4) laminated wood better resists splitting, and
5) the relative amount of expertise (a/k/a experience) required to evaluate
small (thin) peices is less than that required for large (thick) peices.

There is no question that more work, including a lot of clamping, is
required to splice and laminate. But the old timers all swear by it and I
have NEVER heard or read anything in opposition from an experienced source!

That does not mean that I either will or will not use wood as the base
material for a composite, only that I kow it to be a sound engineering
material.

Peter

wrote:
...

Any mention of splicing spars usually sets several heads of hair on
fire, even though such splices are an accepted practice, their details
fully covered in the old CAM or the new AC13 manuals. In fact, once
you've made up a suitable fixture to ensure all of your splices will
have the same angle, doing a long-splice in solid wood is no more
difficult than doing a short-splice in plywood. (Hint: Solid wood,
you want an angle of about 1:15. With plywood, thanks to the
orientation of the plys, you can develop full strength with angles
between 1:10 for mahogany and 1:12 for birch. As a point of interest,
boat builders commonly use 1:8 for either.)

Making up a scarfing fixture tends to drive a lot of homebuilders crazy
as they fiddle and tweak, trying to achieve a precise angle of 3.8
degrees for a long-splice. Or 7.1 degrees for a boat-work 1:8. The
truth is, the precise angle doesn't really matter. What matters is
that all of the pieces be cut to EXACTLY the SAME angle... and that the
splice be strong enough for the task at hand. This degree of accuracy
can be achieved using nothing more complicated than fixtures assembled
from scrap wood, one for scarfing solid stock, the other for scarfing
plywood. In each case the wood gets clamped in the fixture and the
same cutter - - a portable circular saw - - is used on both.


I recommend that Fred pick up and tune a couple of hand planes.
At the very least I think he'll find a block plane and and jack to be
useful, especially for those scarf joints. Old Stanley, Union,
Ohio Tools, Sargent, Millers-Falls, KeenKutter, Winchester, or
Fultons are excellent, and better than any new planes found in
the Borgs today.

--

FF

"Bret Ludwig" wrote in message
ups.com...

wrote:
To All:

A few years ago I posted an article offering some hints about how to
build an inexpensive airplane that was safe and reliable (Flying on the
Cheap, October 2001; Google will find it for you). The key point in
the article was the use of commonly available mild steel tubing for the
fuselage. Of course, that meant you had to weld and nowadays most
folks don't, nor do they want to learn. Wood's the thing,
according to non-welding folks, citing its use in KR's and Piets and
dozens of other airframes, each held as the Perfect Design by that
particular person.

The advocates of wooden airframe construction have a valid point, at
least here in the States. Because of the rise of the box stores (Home
Depot, Lowes, etc), wood is more commonly available than steel tubing
and despite what many think, there's plenty of aviation-quality wood
lurking inside the knot-hole collection at your local box store. The
task of the lo-buck builder is to cut away the non-aviation parts, glue
the good stuff together and go flying. Thanks to modern adhesives, the
likelihood of a novice builder producing an unsafe glue-joint is small.


To support the builders of Box Store Bombers I shared my woodworking
experience in several articles posted to this newsgroup (How to Make
Ribs Out of Old Orange Crates [Nov 2002], Wooden Notes [Jan 2006] and
several others). Surprisingly, homebuilding at that level is not an
especially welcome topic on the rec.aviation.homebuilt newsgroup. This
lead to relaying such information in private posts to guys who were
interested in actually building something. Like Fred. Which isn't
his name, but work with me here.

After considerable thought Fred settled upon a single-place, VW-powered
KR-ish design as being the best match for his particular situation. In
working toward that goal he didn't find much support, especially from
the only organization that claims to speak for grass-roots aviation in
America. Thanks to an income of only $25k or thereabouts, to the EAA,
Fred and the millions of people like him simply do not exist. But Fred
is determined to build and fly his very own airplane, even if he has to
use the local box store for most of his materials. Indeed, he
doesn't have much choice. The total cost for his box store lumber
will be under $100 whereas a kit of aviation-grade spruce would cost
about a thousand dollars by the time the freight was paid. The lumber
will have to be resawn and spliced but that's the reality of Flying
on the Cheap.


Aircraft wood doesn't necessarily have to come from Wicks or Aircraft
Spruce: it has to meet the requirements as set forth in AC 43-13 et
seq. You can find aircraft wood or get it sawn if you know what to look
for. But using wood that clearly is out of those spec is going to cause
trouble.

The biggest problem with flying costs are not traditional simple
airframes: they are the overpriced ridiculous powerplants and high
storage costs.

Direct drive VW made sense in 1965. Not today. Use a liquid cooled car
engine and a redrive, perhaps a Honda since they are attractively
priced as JDM pulls.

I must dissagree. "Fred" appears to have settled on what could be termed a
light, single seat, ELSA which should need roughly 30 to 45 HP. The VW
should be ideal for the purpose.

Peter