what every boy needs - yeah seriously

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

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

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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

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
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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

"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

Peter Dohm wrote:
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.

As I understand it, it doesn't actually work that way. As the power
goes up, an increasing proportion of the heat goes out the exhaust, but
it is probably close enough. According to various reports and Mackerle,
the proportion of heat going into the head goes up though, and the
proportion going into the cylinder goes down, so if you are trying to
maintain the head temp it is likely to be more than 33% difference.

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.

If you could find those texts, they would tell you that when driving a
fan, the power required actually goes up as the cube of the difference
in RPM and the CFM at subsonic speeds scales with the rpm, so doubling
the CFM results in 800% increase in power required. For ram air it is
slightly more complicated, but it essentially rises as a cube of the
airflow as well. NACA did some tests on fan cooled radials and the
Japanese actually deployed some (Kawanishi N1K is one) so there is
research out there. As for the 300% I picked it up off of where I had
actually started to calculate the power difference required for a 33%
increase in HP and a diminished heat transfer coefficient and then left
off unfinished. My mistake, but it understates not overstates the
problem of improving cooling by just increasing the airflow. As in all
things, it depends on just where on the curve you are. The bottom
almost looks like a straight line, the top like a brick wall.

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.

See above....

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.

You would have to figure out how to connect the fan. I think the stock
VW fan moves about 1000CFM at 3000rpm and about 1500CFM at 4000rpm (when
I have been told the belt starts slipping). Veeduber I am sure has the
proper numbers. I don't think it would be a minor thing hooking it up
mechanically and not losing everything you gained in additional weight,
additional drag and HP losses to the fan. If your design speed is slow
enough, I guess you can drop the drag. The Japanese did it with a
geared coaxial fan on a radial, so they had a simpler task. They ended
up with a smaller nose that was almost completely filled with the
spinner and a really small air intake ringing that.

5) As to the real engineering textbooks: BRING 'EM ON.

Peter

On Jan 16, 4:39*pm, Charles Vincent wrote:

You would have to figure out how to connect the fan. *I think the stock
VW fan moves about 1000CFM at 3000rpm and about 1500CFM at 4000rpm (when
I have been told the belt starts slipping). *Veeduber I am sure has the
proper numbers.
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The numbers,, proper or not, are 1300cfm, according to the VW Factory
Service Manual... or whatever... (black covers w/embossed silver
printing). But I think it's a giant LEAP backwards. Somebody out
there is sand-casting VW crankcases in aluminum. Torture them with
lotsnlotsa money and get them to shuffle things around a bit, allowing
a BORE of about 4.625" and a stroke of 88mm, then cast a LONG #1 main
bearing and throw away the tranny flange... might even get them to
cast a Dyna-Focal mount on the other end... and make some entirely NEW
1-cylinder per head headz, and we can stop calling it a VW (although
we'd still be using a lot of VW parts) and start calling it a DIY
Homebuilder Engine... with about 100bhp @ 2700 rpm (or whatever... use
the C-90 cam timing; get someone like Dick (sp?) Schneider to grind us
some wiggle sticks. 40A. coaxial alternator. Itty-bitty geared
starter. Electronic ignition. Holes for two plugs. SIX head-stays.
Juice valves outta the little Chevy. Absolutely NOTHING
certified...although EVERYTHING has done a million miles or more in
other engines. That is to say, there ain't nothing new in such a
design.

Kinda heavy, though... about 181 bare, mostly because of the crank.

-Bluesky Bob

wrote in message
...
On Jan 16, 4:39 pm, Charles Vincent wrote:

You would have to figure out how to connect the fan. I think the stock
VW fan moves about 1000CFM at 3000rpm and about 1500CFM at 4000rpm (when
I have been told the belt starts slipping). Veeduber I am sure has the
proper numbers.
--------------------------------------------------------------------------------------------------------

The numbers,, proper or not, are 1300cfm, according to the VW Factory
Service Manual... or whatever... (black covers w/embossed silver
printing). But I think it's a giant LEAP backwards. Somebody out
there is sand-casting VW crankcases in aluminum. Torture them with
lotsnlotsa money and get them to shuffle things around a bit, allowing
a BORE of about 4.625" and a stroke of 88mm, then cast a LONG #1 main
bearing and throw away the tranny flange... might even get them to
cast a Dyna-Focal mount on the other end... and make some entirely NEW
1-cylinder per head headz, and we can stop calling it a VW (although
we'd still be using a lot of VW parts) and start calling it a DIY
Homebuilder Engine... with about 100bhp @ 2700 rpm (or whatever... use
the C-90 cam timing; get someone like Dick (sp?) Schneider to grind us
some wiggle sticks. 40A. coaxial alternator. Itty-bitty geared
starter. Electronic ignition. Holes for two plugs. SIX head-stays.
Juice valves outta the little Chevy. Absolutely NOTHING
certified...although EVERYTHING has done a million miles or more in
other engines. That is to say, there ain't nothing new in such a
design.

Kinda heavy, though... about 181 bare, mostly because of the crank.

-Bluesky Bob

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

Well, those weight and power numbers look mighty close to the numbers that
Continental is just bringing to market and Lycoming is working on. So, if
you feel the need to swing a 70 or 72 inch prop and ALSO prefer a direct
drive engine that can idle on approach, they are still good numbers.

I could very well be a customer in the easily foreseeable future.

Peter

On Jan 14, 1:10*pm, "Peter Dohm" wrote:

Interesting. *I did not know that the 8 valve VW was lighter than the Type
IV, especially since I believed that it probably had an iron block.

Peter

They are iron blocks, just really nice and thin. But tough. Burn
about 3 gal per hour (18 mpg @55mph) wide open throttle going up the
hills around here in 3rd/4th gear which works out to around 55 Hp?
Not all that much but it never would over heat and 250K+ miles is
quite common. The kids with turbos still didn't have cooling problems
and they are probably a lot closer to the factory 100 or so HP claim.

The 2.0L version with the cross flow head would probably package the
best. I've got one on an engine stand that I was going to put in a
Q2. Decided I don't like Q2's. Still have the PSRU sprokets and a
turbo sitting on the motor.............Got to get rid of some of my
junk.
================
Leon McAtee