what every boy needs - yeah seriously

wrote in message
...
On Jan 8, 3:56 pm, Monk wrote:

A Subaru?
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First off, we can forget about lost-foam or anything more exotic than
green-sand, simply because there aren't enough of us. So we stick to
standard, readily available valves, valve guides, valve seats and
studs. The fins make the castings pretty tricky but if it was easy
you would have seen it years ago.

So we make a L-head and an R-head; mirror images. We do the best we
can with the fins but recognize our limitations and leave the most
difficult of them as CUT fins: Rather than try to cast perfect fins in
a couple of high-risk areas, we settle for a quarter-inch bar of
aluminum that's configured for easy SAWING, which we do as part of the
flash clean-up.

-R.S.Hoover

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

I've alway thought it would be more practical to CNC saw all the cooling
fins. Seems a bit extreme at first glance, but if you go to the time or
expense to fabricate patterns to cast the heads, we must be talk about doing
more than just a couple of sets. So the programming cost might well be worth
the cooling efficency of extremely detailed cooling fins.

On Jan 8, 10:30*pm, "Maxwell" #$$9#@%%%.^^^ wrote:
wrote in message

...
On Jan 8, 3:56 pm, Monk wrote:

A Subaru?

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

First off, we can forget about lost-foam or anything more exotic than
green-sand, simply because there aren't enough of us. *So we stick to
standard, readily available valves, valve guides, valve seats and
studs. *The fins make the castings pretty tricky but if it was easy
you would have seen it years ago.

So we make a L-head and an R-head; mirror images. *We do the best we
can with the fins but recognize our limitations and leave the most
difficult of them as CUT fins: Rather than try to cast perfect fins in
a couple of high-risk areas, we settle for a quarter-inch bar of
aluminum that's configured for easy SAWING, which we do as part of the
flash clean-up.

-R.S.Hoover

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

I've alway thought it would be more practical to CNC saw all the cooling
fins. Seems a bit extreme at first glance, but if you go to the time or
expense to fabricate patterns to cast the heads, we must be talk about doing
more than just a couple of sets. So the programming cost might well be worth
the cooling efficency of extremely detailed cooling fins.

I disagree, sand casting would be easier than milling from solid
block. Just sculpt your head out of wax cover with sand and pour your
casting. A little grinding here and there and there you have it. OK,
not that simplistic, but you get the gist.

"Monk" wrote in message
...
------------------------------------------------------------------------------------

I've alway thought it would be more practical to CNC saw all the cooling
fins. Seems a bit extreme at first glance, but if you go to the time or
expense to fabricate patterns to cast the heads, we must be talk about
doing
more than just a couple of sets. So the programming cost might well be
worth
the cooling efficency of extremely detailed cooling fins.

I disagree, sand casting would be easier than milling from solid
block. Just sculpt your head out of wax cover with sand and pour your
casting. A little grinding here and there and there you have it. OK,
not that simplistic, but you get the gist.

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

I didn't suggest milling from billet. Just milling the cooling fins. The
overall head with valley for the rockers, combustion chambers, ports, etc.,
should be green sand cast.

It's also not possible to green sand cast over a wax investment. Even if it
were simple enough to sculpt your heads out of wax, which it's not, you
would have to investment cast them.

Sand casting the heads and machining detail not practical with the green
sand or air set process is the only practical method for producing a limited
number of parts. Tooling cost for wax or foam investment casting would be
too prohibitive.

First off, we can forget about lost-foam or anything more exotic than
green-sand, simply because there aren't enough of us.

Lost foam isn't all that "high tech" and is actually well within the
ability of anyone that can build their own foundry and ram up some
sand. Classic lost wax is still a viable option and if one uses oil
based sand rather than bentonite green sand you can get much better
detail and steeper angles - but you do need a muller for oil sand.

Here again, borrow a page from the Corvair (or from GM) and we end up
with a 'rocker arm' that actually works. *The tricky bit is that it
does NOT need to be aligned on a shaft... we can literally put a valve
anywhere there is room. *And that means at any angle as well.

My conclusion as well - but if the angles aren't chosen very carefully
we end up with greater than stock side loads on the lifters - thus my
conclusion that we need a new cam at some point or run the risk of
accelerated lifter bore wear. Trying to put a second plug in the mix
and I'm not smart enough to come up with angles that I'm comfortable
with.

Personally I see no need for 2 plugs per cylinder. When was the last
time anyone heard of a spark plug failing with out warning? As for
flame front prorogation, the only real justification for dual plugs
other than unreliable magnetos, we just don't need them on a VW based
engine unless you start thinking high rpm's and a PSRU. But that's
getting too far away from the cheap and simple.


So we make a L-head and an R-head; mirror images. *We do the best we
can with the fins but recognize our limitations and leave the most
difficult of them as CUT fins

If we do the split heads (still need 2 cores, front and rear) the fins
can be rough cast and then finished up on a lathe. The mention of
sawing gives me the idea of using a saw mounted on the lathe for
quicker cutting than a standard tool and maybe even thinner fins. Band
saw off the fins next to the other head and your done. No CNC
needed. My next set of 1/2 VW heads will be done this
way................if I ever get around to a next set.
=======================
Leon McAtee

On Jan 8, 11:21*pm, "Maxwell" #$$9#@%%%.^^^ wrote:
"Monk" wrote in message


It's also not possible to green sand cast over a wax investment. Even if it
were simple enough to sculpt your heads out of wax, which it's not, you
would have to investment cast them.

While sand directly over wax isn't practical there are hybrid methods
of lost wax and sand that the hobby casters can do with good results.
As for being simple to sculpt the heads in wax ...........depends on
your definition of simple.


Tooling cost for wax or foam investment casting would be
too prohibitive.

If your thinking conventional production practices you might be right,
but there are home brew methods that while slower work just fine. We
aren't talking GM production numbers or that level of automation.
====================
Leon McAtee

On Thu, 8 Jan 2009 11:34:36 -0800 (PST), "
wrote:


issue, which is guys like you & me. In my case the fact I live well
below the 'official' poverty line renders me invisible. Which means I
can build and fly as much as I want to, without having any effect at
all upon the Important Decisions which shape the future of American
aviation (and Australian too, when you get down to it).

-R.S.Hoover

this will be no consolation but I've just thrown in a job that
returned me somewhere between $80,000 and $100,000 per year to move
below the poverty line.
I've become my wife's carer as her psyche problems worsen.

so I will be *making* my next aircraft. the turbulent will have all
manner of bits cast and machined by me.

as a model engineer I'd like to make an accurate altimeter, an
accurate air speed indicator....

y'know this *is* fun.

Stealth Pilot

On Fri, 09 Jan 2009 01:11:48 GMT, Jerry Wass
wrote:

Stealth Pilot wrote:
veedubber and others
the venerable old VW engine conversion is quite usable.

if you were to take all the lessons learnt from all the engine
building done so far and apply them to a new engine design, what would
the new engine design look like?

I think the flat 4 makes a very serviceable aircraft engine.
underslung pushrods like the O-200 and VW would remain.
I'd use hydraulic lifters.
the castings for the crankcase would be simpler, more like the O-200
than the complexities of the VW casing.
the crankshaft would be a little more robust at the front end
I'd fin the pushrod tubes and use the oil returning to the crankcase
as a radiator.
the engine would be mounted on dynafocal lord mounts.
I'd use electron for the crankcasings.
spin on oil filter. (z79)
magnet in the sumpplug.

what else???

Stealth Pilot


Would you please expand on "electron for crankcasings"

electron is a magnesium - aluminium alloy. lighter and stronger than
plain aluminium alloy for the casings. I'm pretty sure it is what vw
used in the casings.
however it doesnt lend itself to home greensand casting techniques
unless you can put an argon atmosphere above the molten metal.
the magnesium burns brightly at the surface of the molten metal.

stealth pilot

On 8 Jan, 17:37, Stealth Pilot
wrote:
veedubber and others
the venerable old VW engine conversion is quite usable.

if you were to take all the lessons learnt from all the engine
building done so far and apply them to a new engine design, what would
the new engine design look like?

I think the flat 4 makes a very serviceable aircraft engine.
underslung pushrods like the O-200 and VW would remain.
I'd use hydraulic lifters.
the castings for the crankcase would be simpler, more like the O-200
than the complexities of the VW casing.
the crankshaft would be a little more robust at the front end
I'd fin the pushrod tubes and use the oil returning to the crankcase
as a radiator.
the engine would be mounted on dynafocal lord mounts.
I'd use electron for the crankcasings.
spin on oil filter. (z79)
magnet in the sumpplug.

For a new design I really really really like this -
http://www.deltahawkengines.com/
http://www.deltahawkengines.com/status00.shtml
http://www.deltahawkengines.com/Broc...osh_2003.shtml
http://www.deltahawkengines.com/specif00.shtml

It's a water cooled two stroke diesel.

Fuel availability (Kerosene etc)
Fuel efficiency at cruise power
No valves/valvetrain
No electrics needed for operation
Can safely run for a while without coolant too.

Obviously the sizes that they are making (160hp +)
are too big for your requirement but I doubt that there
is a fundamental reason that a smaller one could
not be made.

My one worry (for which I have no information) would
be that it might be noisy - dont know.

On Jan 8, 2:34*pm, " wrote:
All of that is out there, already available. *But the truth is, it's
not needed; not in the immediate sense.

What IS needed are aluminum head-castings having twice as much fin-
area as what's presently available. *This won't fit on a bug or bus so
there is no start-up money. *Coming up with the cores should have been
done by the EAA -- about fifty years ago. *The fact it wasn't *is good
evidence that it won't.

Bob...don't Jabiru use heads machined from billet stock?

On Jan 8, 7:30*pm, "Maxwell" #$$9#@%%%.^^^ wrote:

I've alway thought it would be more practical to CNC saw all the cooling
fins. Seems a bit extreme at first glance, but if you go to the time or
expense to fabricate patterns to cast the heads, we must be talk about doing
more than just a couple of sets. So the programming cost might well be worth
the cooling efficency of extremely detailed cooling fins.
------------------------------------------------------------------------------------------------------------------------
Dear Maxwell, et al

(more for the et al's at this point)
What makes this NOT a ' blue-sky & bull**** ' kinda project is the
fact we can pick up a telephone and have the key components sitting on
our front porch in a matter of HOURS. Such as:

Pistons & cylinders, crankshafts, camshafts, valves, valve seats,
valve guides, carburetors, electronic ignition components, electrical
system components... and so on right down the list.

In fact, the existence of the Roto-Way type heads... most folks think
of them as 'Scat-type'... provides 'Proof of Concept' -- meaning this
IS NOT a new idea. What's 'new' is coming up with an isolated head-
design that is amenable to air-cooling.

Historically, when the real engine manufacturers ran into the thermal
limitations of cast aluminum (**) they way they tackled the task
serves as our instruction manual. They tried liquid cooling and
machined fins but finally achieved the desired power-to-weight ratio
by going to FORGINGS for their aluminum heads.

(Forged aluminum is denser; it can couple more heat to the atmosphere
than a casting can. [and if one you grammarians jumps on that...] ).
Indeed, comparing the American & British efforts makes a damn good
adventure novel -- one in which the British should have won (ie,
because of their slide-valve engines). But buried in that 'novel' is
methods tried & discarded not because they didn't work but simply
because the goal was for more horsepower than those methods could
provide. And to be fair here we really need to include the Japanese
14-cyl radial... which was using the so-called 'Singh Grooves' in the
early 1940's, allowing them to run on 70 octane tractor gas.)

In fact, we can even use the Lycoming O-145 as a good model of how NOT
to do things. (Yeah, it produced 65hp... but only when you spun it up
above 3000 rpm. Stuck on the nose of a Piper 'Cub' it was a TERRIBLE
powerplant, simply because it produced all of its thrust in a narrow,
high-velocity slug of accelerated air into which the fuselage of the
Cub was buried. And as we know (and Lycoming seemed to forget), drag
increases as the SQUARE of velocity. But AFTER the war, when a bright
young fellow named Mooney came along with a sleek little single-place
design, the O-145 finally came into its own... because there was
simply no comparison to the induced drag of a Cub and a Mite.

So what's our engine gonna be? It's going to be what it ALREADY IS, a
set of 94mm jugs atop an 84mm Chinese crankshaft. But the difference
is in the HEADS. And it's not even the WHOLE head we're talking
about, just the outer portion that is associated with the exhaust
stacks. This is the HOTTEST part of the VW engine. VW's engineers
did some truly remarkable things to ensure the CORNERS of the engine
got the MAJORITY of the cooling air. Unfortunately, when you try to
do that using RAM-AIR instead of a blower, you run into all sorts of
problems, most of which can be resolved by simply increasing the AREA
of the cooling fins.

And how do we do that? (Someone asks) ...or, Why hasn't someone done
that? (another asks)... and in both cases the answer is pretty much
the same: We do it by altering the shape of the exhaust outlet, and
YES, someone has ALREADY DONE THAT... if you're familiar with the
Porsche engine.

The point here is that it's not a big change, in engineering terms.
Nor even an especially difficult change. The main problem is that all
previous efforts were aimed at CAR engines, which presented some space
limitations that they simply could not resolve if they wanted the
engine to fit in the car. Bottom Line: They came up with a new car-
body that provided enough room for the 'fatter' engine -- 'fatter'
because it had more fins. And put that fatter engine into airplanes,
too. Which means we're not quite the ground-breakers we think we
are :-)

So what's the basis of our 'success'? Easy! We simply re-design the
exhaust to dump out the BOTTOM of the head, as GM did with the
Corvair... and which VW could NOT do with the VW engine. When the
exhaust stack is moved outta the way it gives us access to the upper-
outer corner of the head for each of the jugs, and that is where we
install our additional fins. Not only do we add additional fins, we
increase the size of the fins that are already there, so that our
maximum PEAK output comes up to something on the order of 80hp, whilst
our maximum SUSTAINABLE output is about 60hp (Standard Day
assumed).

Does this give us a 'thousand hour' engine? Hell no! Lookit the
bearing area. At that level of output you'll be lucky to get a TBO of
500 hours. Of course, replacing every bearing in the engine will only
run you about sixty bucks.

Sure sounds easy, eh? In fact, if it's so damn easy you gotta wonder
why I haven't already done it. Surprise! I already did... sorta. We
called it the 'Fat Fin' head and tried to accomplish what I've
described here by TIGing on additional fin area to stock heads. Which
didn't work for a lot of reasons, but there were some examples that
DID work... until the fins warped or the valves overheated or any one
of a dozen other things. Plus the biggie: Fat Fin heads would not
fit in a VEHICLE. And without that market, they were little more than
a joke... some crazy ol' guy wanting to put a VW engine in an
airplane, for crysakes!

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

How do you get in touch with OTHER 'crazy ol' guys?' Back then, you
got Pope Paul to put a notice in the magazine. Remember all them
notices? Yeah. I don't either.

But now we got the Internet.

Tell you what... Somewhere in my drawings I've got a stock VW head,
sorta -373'ish (that's a VW part number... don't sweat it). I'll dig
it out, convert it into a .jpg and post it on my blog. Then you can
blow it up to near-full-scale and print it out. One it's printed, you
can start fooling with the location of this & that... moving the
exhaust stack... which is when you'll discover that a push-rod and an
exhaust stack will NOT peacefully co-exist :-) But there's a couple
of ways in which they WILL... expect they put one hell of an angle
onto the push-rod... and you gotta move the rocker-arm around... stuff
like that. THAT'S what we're talking about here. Once we can move
the exhaust stack WITHOUT trashing the push-rod, we can increase the
cooling-fin area by about 25%... mebbe more.

Best of all (mebbe) is that we'll come up with a casting that the
average home machinist can turn into a cylinder head. And that will
only take another 10,000 words or so... plus a few hundred
pitchers... if anyone is interested.

-R.S.Hoover


And just for Flavor of the Month -- sump plate