what every boy needs - yeah seriously

"Anyolmouse" wrote in message
...

"oilsardine" wrote in message
...
: fan-cooled VW/Porsche http://popnet.ch/reichen/HB207/image035.htm
:
: it's the powerplant of a ALFA HB 207, quite a few flying here in
Europe
: http://popnet.ch/reichen/HB207/index.htm
:
:
: "Anyolmouse" schrieb im Newsbeitrag
: ...
:
: wrote in message
:
...
: On Jan 14, 4:55 pm, "Peter Dohm" wrote:
:
: I am really not dissagreeing with you--as the pressure system that
I
: am
: thinking of would use a VW type cooling fan to augment the ram air
: pressure.
: That would be a rather obvious source of added weight and an easily
: visible
: use of power--and would never be popular.
:
---------------------------------------------------------------------
-
: --------
:
: The trouble with the coaxial blower mods was the SAME as with the
: turbo people, in that there simply was not enough fin area for the
: increased density/flow to do much good. Everyone seemed determine
to
: get "60hp" sixty mythical horsepower from an engine that in its most
: powerful configuration only produced 57bhp @ 4400rpm.... and you
only
: got to pull that for something less than 5 minutes.
:
: So you increase the displacement to something seriously silly and
: USING THE SAME HEADS & FIN AREA start pulling as much as 85hp(!!)
from
: that configuration... and wondering why things weren't working
right.
:
: Maximum SUSTAINABLE OUTPUT of the '1600' (displacement 1584cc) under
: Standard Day conditions was something like 36bhp, whereas PEAK
OUTPUT
: can be just about anything you're willing to pay for. It doesn't
blow
: up (although it can) but it blows your bhp right into the porcelain
: fixture.
: SNIP
: -R.S.Hoover
:
: Hope you don't mind my jumping in here Bob. Do you remember the
Porsche
: engine with the cooling fan behind the prop? It was supposed to
: eliminate the need for cowl flaps and also prevent shock cooling
too.
: What happened to it?
:
: --
: Anyolmouse
:

Nice site. It isn't the same configuration as the one I saw in a
magazine here in the US though. There was a large air intake filled with
a fan just behind the prop. The fan was supposed to supply all the
cooling needed and protect the engine from over cooling from ram air as
well as supply cooling during taxi and low speed operation.

--
Anyolmouse

What you describe is basically what I had in mind. It would most commonly
be accomplished with an annular intake; but could be done in several ways,
mostly depending on the specifics of how the prop is driven.

Peter

"cavelamb" wrote in message
...
---------------preceding posts snipped------------------

I am really not dissagreeing with you--as the pressure system that I am
thinking of would use a VW type cooling fan to augment the ram air
pressure. That would be a rather obvious source of added weight and an
easily visible use of power--and would never be popular.

Interestingly, the guys I knew who broke cranks (amoung other interesting
problems) were also flying KR2s--although they were based in Florida.

Personally, that is not a level of reliability that I could accept; and I
have never considered an application that I believed would draw much more
than 40 HP continuously from a VW--even though I have been willing to
consider ideas that asserted a theoretical peak power of 60 HP.


I've always thought that the broken cranks were the cast versions not
forged cranks.


I've never heard of anyone breaking a forged crank.

FWIW

Richard

I had thought that as well, but it appears that my information was
incomplete and Veeduber included some probable reasons in an adjacent post.

In any case, the broken cranks that locally came to my attention occurred in
the range of 150 to 160 hours of operation and I was told at that time that
failures of that type were well known at a similar time in service.
Although I no longer recall what I was told about the exact nature of the
breaks, the engines involved were driving props on the accessory end and the
failure was probably the gradual crack progression that Veeduber describes
from a point between the threads and the woodruff key slot.

Peter

On Jan 15, 6:23*am, "Anyolmouse" wrote:

Hope you don't mind my jumping in here Bob. Do you remember the Porsche
engine with the cooling fan behind the prop?
---------------------------------------------------------------------------------------------------

If you mean the engine for the British blimp, yeah, I remember it.

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

It was supposed to
eliminate the need for cowl flaps and also prevent shock cooling too.
What happened to it?

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

They had trouble with the blimp, as best I can recall.

Come on... you should be able to remember it. It was in most of the
magazines back then.

The blimp could not provide the forward velocity needed to cool the
engine, so instead of going to Fat Fins or any of the other possible
solutions (the Porsche engine was already Type Certified -- they
couldn't mess with it without running into the CAA. So they came up
with the idea of providing a 140mph cooling air-flow INSIDE THE
COWLING. The engine didn't know any better. It would stick out it's
toe, feel that blast of 140 mph cooling air and say, "Oh goody!" (but
in Chermann of course) and fly off into the sunset... with half a
dozen tourists on-board (at about $50 per, as I recall). Quick tour
around the pea-patch, niffty landing to the portable Pylon Tower,
commerative T-shirts, coffee mugs and an autographed picture of the
Fearless Aviator, and off they go for another trip around the pea
patch.

Ah, the wonders of aviation...

It wasn't the ENGINE'S fault that the thing was not a howling
success... and the truth is, I've forgotten the details as to WHY it
was not a success... if I ever even knew them.

-Bob

On Jan 15, 8:13*am, "Anyolmouse" wrote:

Nice site. It isn't the same configuration as the one I saw in a
magazine here in the US though.
--
Anyolmouse

Are you thinking about the Mooney/Porsche?

http://upload.wikimedia.org/wikipedi...e_PFM_3200.jpg

wrote in message
...
On Jan 15, 6:23 am, "Anyolmouse" wrote:

Hope you don't mind my jumping in here Bob. Do you remember the
Porsche
engine with the cooling fan behind the prop?
------------------------------------------------------------------------
---------------------------

If you mean the engine for the British blimp, yeah, I remember it.

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

It was supposed to
eliminate the need for cowl flaps and also prevent shock cooling too.
What happened to it?

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

They had trouble with the blimp, as best I can recall.

Come on... you should be able to remember it. It was in most of the
magazines back then.

The blimp could not provide the forward velocity needed to cool the
engine, so instead of going to Fat Fins or any of the other possible
solutions (the Porsche engine was already Type Certified -- they
couldn't mess with it without running into the CAA. So they came up
with the idea of providing a 140mph cooling air-flow INSIDE THE
COWLING. The engine didn't know any better. It would stick out it's
toe, feel that blast of 140 mph cooling air and say, "Oh goody!" (but
in Chermann of course) and fly off into the sunset... with half a
dozen tourists on-board (at about $50 per, as I recall). Quick tour
around the pea-patch, niffty landing to the portable Pylon Tower,
commerative T-shirts, coffee mugs and an autographed picture of the
Fearless Aviator, and off they go for another trip around the pea
patch.

Ah, the wonders of aviation...

It wasn't the ENGINE'S fault that the thing was not a howling
success... and the truth is, I've forgotten the details as to WHY it
was not a success... if I ever even knew them.

-Bob

It was in one of the aviation magazines with picture(s) of it in an
airplane. Didn't see any reference to a blimp in the write up. I wish I
could recall more about it. Thanks for the reply though-

--
Anyolmouse

wrote in message
...
On Jan 15, 8:13 am, "Anyolmouse" wrote:

Nice site. It isn't the same configuration as the one I saw in a
magazine here in the US though.
--
Anyolmouse

Are you thinking about the Mooney/Porsche?

http://upload.wikimedia.org/wikipedi...e_PFM_3200.jpg

Could be it without the fan and prop.

--
Anyolmouse

On Jan 15, 10:41*am, " wrote:

It wasn't the ENGINE'S fault that the thing was not a howling
success... and the truth is, I've forgotten the details as to WHY it
was not a success... if I ever even knew them.

History repeats. Only this time the government is paying the bill for
a Porsche powered English blimp.

http://www.navair.navy.mil/PMA262/bl...0July2008.html

http://en.wikipedia.org/wiki/Skyship_600
===============
Leon McAtee

wrote:
On Jan 14, 11:10 am, "Peter Dohm" wrote:
wrote in message

...
On Jan 13, 10:06 pm, "Peter Dohm" wrote:

At the obvious cost of proving myself a heretic regarding VWs....
We could go back into the old debate about whether a nearly stock VW
engine
could be a reliable 50 to 60hp powerplant with the right sort of pressure
cooling system. With all due respect to Bob, a/k/a Veeduber, I am still
convinced that it can
----------------------------------------------------------------------------------------

Mybe it CAN. All I'm saying is that it never happened for me and I
gave it a pretty good go. Failures ALWAYS pointed to excessive
heating/lack of cooling.


Doubling the velocity of the air through a given cooling fin design only
gives a 60% or so improvement, but of course, the cost of accelerating
that air is operating on a curve going the opposite direction, i.e. it
takes 300% of the energy. Low horsepower designs use thick short
widely spaced fins with a turbulent air stream for the most efficient
cooling (i.e. least power) The fact that these are cheaper to build just
happens to work with the model that low horsepower designs are applied
to. The longer a fin is, the less efficient it is. So the VW head needs
more fins, not just longer fins, or even more air. All of this is
exacerbated by the fact that as load goes up, the percentage of heat in
the cylinder head vs the cylinder itself goes up disproportionately.
Same thing happens with RPM. So punching them and revving them to get
more horsepower just highlights the limitation of the original design.
I can of course cite sources for all of this, but real engineering
textbooks are frowned upon, so to go with the flow, I will ascribe it
all to a friend of my cousin named Mackerle and his partner Liston who
has been building these things for years and stuff and knows all about
it.

Charles

On Jan 15, 10:43*am, "
wrote:
History repeats. *Only this time the government is paying the bill for
a Porsche powered English blimp.
--------------------------------------------------------------------------------------------------------------------------------

I'm delighted to see that my Memory Bone has not been attacked by this
cancer :-) But I'm still stuck with trying to recall the details that
went into a successful finned pattern, as explained to me (about 40
years ago!!) by a fellow Chief. I really hate to say it but my best
recollection of FINS was that in each case, the FIN had to be made of
two pieces of CLEAR lumber, glued back-to-back. For example, to
produce a 1/8" fin, measured at the tip, you had to start with two
pieces of clear wood about 3/16" (each!) at the root or base of the
fin. These were then sanded or planed so as to provide a MINIMUM
draft of 1/8".

Right now I'm looking at FIFTEEN fins (vs the stock VW head's which
have only eight).

Using the best head I could find (I had no idea how many of the damn
things I've accumulated!) and making up half a coffee-can of green
sand (using a mix of aluminum oxide(?) & #100 silica, there's no way
in the world I can come up with a green-sand having enough strength to
produce a fin even as deep as the STOCK depth (ie, approximately 1").
Plus, I run into an interesting problem: With a draft of 1/8" and a
depth of 1", things appear to work out pretty well. But to then make
the depth ANY GREATER than 1" I will have to increase the distance
between the fins, which is presently 1/4" for the four HOTTEST fins
but only 3/16" apart for the five coolest fins. Then comes the main
problem: I don't have a planer, which sanding down each of the
'biscuits' I'll need to make the fins.

Then comes an even trickier problem: There is a clear parting line
showing how the fins were rammed-up & parted but the flask holding the
fins next to the valve gallery has to make use of a false bottom (I
know what it is but I've forgotten the name of the thing) so that you
end up using three flasks, one of which is rammed and pulled
perpendicular to the other two.

-Bob

"Charles Vincent" wrote in message
...
wrote:
On Jan 14, 11:10 am, "Peter Dohm" wrote:
wrote in message

...
On Jan 13, 10:06 pm, "Peter Dohm" wrote:

At the obvious cost of proving myself a heretic regarding VWs....
We could go back into the old debate about whether a nearly stock VW
engine
could be a reliable 50 to 60hp powerplant with the right sort of
pressure
cooling system. With all due respect to Bob, a/k/a Veeduber, I am still
convinced that it can
----------------------------------------------------------------------------------------

Mybe it CAN. All I'm saying is that it never happened for me and I
gave it a pretty good go. Failures ALWAYS pointed to excessive
heating/lack of cooling.


Doubling the velocity of the air through a given cooling fin design only
gives a 60% or so improvement, but of course, the cost of accelerating
that air is operating on a curve going the opposite direction, i.e. it
takes 300% of the energy. Low horsepower designs use thick short widely
spaced fins with a turbulent air stream for the most efficient cooling
(i.e. least power) The fact that these are cheaper to build just happens
to work with the model that low horsepower designs are applied to. The
longer a fin is, the less efficient it is. So the VW head needs more fins,
not just longer fins, or even more air. All of this is exacerbated by the
fact that as load goes up, the percentage of heat in the cylinder head vs
the cylinder itself goes up disproportionately. Same thing happens with
RPM. So punching them and revving them to get more horsepower just
highlights the limitation of the original design. I can of course cite
sources for all of this, but real engineering textbooks are frowned upon,
so to go with the flow, I will ascribe it all to a friend of my cousin
named Mackerle and his partner Liston who has been building these things
for years and stuff and knows all about it.

Charles

I really had decided to let this whole matter slide; since, in the end,
everything that I might actually want to build would require 80 to 120
horsepower--and more if I really want the aircraft to have utility for
transportation. So this mostly an intellectual exercise.

However, since you phrase your response in the above manner:
1) To get from a thermal limitation of 45 horsepower to 60 horsepower looks
like a 33% increase. If you dissagree, please respond to
Hewlett-Packard--since I have been using their calculators for the past 25
years or so.
2) Doubling the velocity of airflow should require 400% (not 300'%) of the
energy, according to the old engineering texts that I can no longer find.
3) By the combining the above calculations, and using the latest trusty
Hewlett-Packard calculator, the 33% increase in cooling should require 177%
of the energy.
4) The basic point was that: if you climb at 60 (kph, mph, kts, or
whatever) and you would need to be climbing at 90 to adiquately cool the
engine; then the difference could be made up by the addition of a cooling
fan.
5) As to the real engineering textbooks: BRING 'EM ON.

Peter