http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg


That .3v per cell matters at times.

I took the liberty of putting links in for you.

Did you rework it or did you make it from scratch?

Wes

On 4/2/2010 08:33, Wes wrote:
Tim wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

Whoever took the pictures - nice hustle, but perhaps you could use the
macro setting to focus close-in, or set the aperture to a higher F stop
(like F 5.6 or greater)

On some pics, you can see things came into focus past the object.

PS. Of course, higher F stop means less light. F 8 brings everything
into focus, but reduces the amount of light.

Louis Ohland wrote:
On 4/2/2010 08:33, Wes wrote:
Tim wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

Whoever took the pictures - nice hustle, but perhaps you could use the
macro setting to focus close-in, or set the aperture to a higher F stop
(like F 5.6 or greater)

On some pics, you can see things came into focus past the object.

PS. Of course, higher F stop means less light. F 8 brings everything
into focus, but reduces the amount of light.

I was going to apologize for the crappy pictures. That _is_ with a
macro, although it's the camera's built-in macro setting which, while it
does put a pretty picture of a flower in one corner of the view screen,
doesn't let you get much closer than a foot. I should have gone back
and taken more pictures when I found just how bad it is, but I'm lazy.

Maybe today.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

In article ,
Tim Wescott wrote:

Louis Ohland wrote:
On 4/2/2010 08:33, Wes wrote:
Tim wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

Whoever took the pictures - nice hustle, but perhaps you could use the
macro setting to focus close-in, or set the aperture to a higher F stop
(like F 5.6 or greater)

On some pics, you can see things came into focus past the object.

PS. Of course, higher F stop means less light. F 8 brings everything
into focus, but reduces the amount of light.

I was going to apologize for the crappy pictures. That _is_ with a
macro, although it's the camera's built-in macro setting which, while it
does put a pretty picture of a flower in one corner of the view screen,
doesn't let you get much closer than a foot. I should have gone back
and taken more pictures when I found just how bad it is, but I'm lazy.

Maybe today.

I find that a textured background helps the camera autofocus a lot. Most
cameras cannot autofocus on mirror surfaces.

What also helps is a big flash to fill the room with light.

And, to respect the lens' minimum distance, but it's easy to get fooled.

Joe Gwinn

Wes wrote:
Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg


That .3v per cell matters at times.

I took the liberty of putting links in for you.

Did you rework it or did you make it from scratch?

From scratch -- I only have one high compression head, and it's still
good. There's no way I'm cutting that up!

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Tim Wescott wrote:

Did you rework it or did you make it from scratch?

From scratch -- I only have one high compression head, and it's still
good. There's no way I'm cutting that up!


Did you take pictures of your setups as you made it?

Wes

Wes wrote:
Tim Wescott wrote:

Did you rework it or did you make it from scratch?
From scratch -- I only have one high compression head, and it's still
good. There's no way I'm cutting that up!


Did you take pictures of your setups as you made it?

Didn't think of it -- I just took an aluminum bar and hacked away
everything that didn't look like what I wanted.

I don't know that doing so would have been a public service, other than
an example of how one hack-job amateur took care of the work.

I'm planning on doing a few, to experiment with compression ratios and
combustion chamber shape, so I'll think about doing it then.

I'm on a bit of a mission. You can get these adapters, but the word on
the street is that they don't work as well as the Cox heads, because not
much attention is paid to combustion chamber shape. So I'm interested
not only in "can I make this work", but "can I make this work well", and
"can I make this work for low nitro fuel".

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Tim Wescott wrote:

Wes wrote:
Tim Wescott wrote:

Did you rework it or did you make it from scratch?
From scratch -- I only have one high compression head, and it's still
good. There's no way I'm cutting that up!


Did you take pictures of your setups as you made it?

Didn't think of it -- I just took an aluminum bar and hacked away
everything that didn't look like what I wanted.

I know how that works. I've been working away on a Gatlingun and the camera has never
been in the shop. I really should take pictures.

I don't know that doing so would have been a public service, other than
an example of how one hack-job amateur took care of the work.

Believe it or not, showing a way is a service.


I'm planning on doing a few, to experiment with compression ratios and
combustion chamber shape, so I'll think about doing it then.

That would be fantastic.

I'm on a bit of a mission. You can get these adapters, but the word on
the street is that they don't work as well as the Cox heads, because not
much attention is paid to combustion chamber shape. So I'm interested
not only in "can I make this work", but "can I make this work well", and
"can I make this work for low nitro fuel".

I hope you have success. Have you ever been to NAMES or one of the other model
engineering expos?

Wes

Wes wrote:

Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

That .3v per cell matters at times.


A fresh carbon zinc is closer to 1.55 volts. 1.2 volts would be a
little over a 40% reduction in power dissipate in the glow plug.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

Michael A. Terrell wrote:
Wes wrote:
Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.
http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

That .3v per cell matters at times.


A fresh carbon zinc is closer to 1.55 volts. 1.2 volts would be a
little over a 40% reduction in power dissipate in the glow plug.

It goes lower than that when you load it up with a glow plug. The power
reduction wouldn't be quite 40%, as the resistance goes down with
temperature -- but it's still enough of a drop that the engine gets to
be quite a bit harder to start.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

Tim Wescott wrote:

Michael A. Terrell wrote:
Wes wrote:
Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.
http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

That .3v per cell matters at times.


A fresh carbon zinc is closer to 1.55 volts. 1.2 volts would be a
little over a 40% reduction in power dissipate in the glow plug.

It goes lower than that when you load it up with a glow plug. The power
reduction wouldn't be quite 40%, as the resistance goes down with
temperature -- but it's still enough of a drop that the engine gets to
be quite a bit harder to start.


It doesn't take much, plus I've seen people try to use a lot more
wire than they need which adds to the droop.

--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

"Michael A. Terrell" wrote in message
...

Wes wrote:

Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

That .3v per cell matters at times.


A fresh carbon zinc is closer to 1.55 volts. 1.2 volts would be a
little over a 40% reduction in power dissipate in the glow plug.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

There seems to be a lot of difference in the internal resistance of the
batteries too. For example, it would be interesting to measure the voltage
at the glow head using a Sub C Nicad versus a C cell carbon zinc, I doubt
there would be a 40% difference, the Nicad might even deliver more voltage
to the glow head. However using a 1.5V lantern battery sized carbon zinc
cell would get the voltage up there. For glow plugs I use either 1.2V
rechargeable or my power panel glow driver, I guess the power panel would be
better for Cox engines but I haven't used them enough in R/C to notice a
difference.

RogerN

RogerN wrote:
"Michael A. Terrell" wrote in message
...
Wes wrote:
Tim Wescott wrote:

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.
http://www.metalworking.com/dropbox/cox_head.txt
http://www.metalworking.com/dropbox/cox_head-inside.jpg
http://www.metalworking.com/dropbox/...d-on_plane.jpg
http://www.metalworking.com/dropbox/cox_head-plans.jpg
http://www.metalworking.com/dropbox/cox_head-top.jpg

That .3v per cell matters at times.

A fresh carbon zinc is closer to 1.55 volts. 1.2 volts would be a
little over a 40% reduction in power dissipate in the glow plug.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

There seems to be a lot of difference in the internal resistance of the
batteries too. For example, it would be interesting to measure the voltage
at the glow head using a Sub C Nicad versus a C cell carbon zinc, I doubt
there would be a 40% difference, the Nicad might even deliver more voltage
to the glow head. However using a 1.5V lantern battery sized carbon zinc
cell would get the voltage up there. For glow plugs I use either 1.2V
rechargeable or my power panel glow driver, I guess the power panel would be
better for Cox engines but I haven't used them enough in R/C to notice a
difference.

For the Cox engines I was told to use two D size alkaline cells in
parallel. I do that, with good thick wires, and it works like a charm.
I use 3/16" (I think that's the size) copper tube on the batteries,
which is just the right size for banana plugs, good thick not-too-long
wires, and a Sulivan clip. It works like a charm.

For the conversion heads with glow plugs, I use a little bitty
Ni-starter -- whee!

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

RogerN wrote:

There seems to be a lot of difference in the internal resistance of the
batteries too. For example, it would be interesting to measure the voltage
at the glow head using a Sub C Nicad versus a C cell carbon zinc, I doubt
there would be a 40% difference, the Nicad might even deliver more voltage
to the glow head. However using a 1.5V lantern battery sized carbon zinc
cell would get the voltage up there. For glow plugs I use either 1.2V
rechargeable or my power panel glow driver, I guess the power panel would be
better for Cox engines but I haven't used them enough in R/C to notice a
difference.


The resistance of both types go up with age. Some people use an ESR
meter to measure the internal reistance of each cell.


--
Lead free solder is Belgium's version of 'Hold my beer and watch this!'

Tim Wescott wrote:
http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.

Nicely done. I tried to do this back in '68
when I was 16. I had a Wen-Mac engine and
couldn't get glow plugs for it any more. I
don't think I was able to tap a good enough
hole and I never got mine to work.

Nice. What were the closest tolerances that you had to hold? Bob

Bob Engelhardt wrote:
Nice. What were the closest tolerances that you had to hold? Bob

'bout that much.

Seriously -- since I wasn't trying to hold to a particular compression
ratio, the only really critical parts were the threads and seats. The
glow plug was taken care of with a 1/4-32 tap, and the seats just needed
to be flat and smooth. I almost cut the mounting threads too deep --
they turned out to be just about the right size after my last rough cut,
and I had anticipated a few finish cuts to get that part right (I'm
still far from a thread-cutting expert).

If anything I missed on the step up to the squish band, and the
combustion chamber -- given that the thing needs 3 x 0.005" gaskets, I
should have made the whole thing 10 mils deeper. With just one head
gasket you could hear the preignition (or the piston whacking the head,
but I think it was preignition).

Making the _next_ one is going to challenge my ability to hold tolerances!

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

"Tim Wescott" wrote in message
...
http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel. I
couldn't do that with the stock head; I think it just didn't have enough
compression. This head has stupid-high compression* -- it runs better
with a stack of three head gaskets than it does with none (I need to try
it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing indicates,
and wider fin spacing.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

That's pretty nice! I have a Norvell engine that I'm not sure if glow plugs
are still available for, if not I may be making an adapter similar to that
some day.

I used to want one of the Davis Diesel conversion heads for the COX .049s
but never got one. I still think it would be fun to play with, just not
sure how practical they are.

I have a "Tarno" carburetor from years ago, fits on a Cox TD.049/.051 engine
and gives you throttle control, I never used it, they may be worth something
these days.

RogerN

On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.


Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Cheers,

John D.
(jdslocombatgmail)

John wrote:
On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.


Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Oops -- I left that out.

Its a reed-valve engine, built from a bucket-o-engines with a Babe-bee
case and tank, but with a two-bypass cylinder as often came on the
'product' engines that went into the ready-to-fly airplanes.

There were two rotary-valve engines: the Medallion (sport) and the
Tee-Dee (competition) engine. The Medallion had a red plastic venturi,
while the Tee-Dee had an aluminum one. I never had the bucks for such
fancy things, so I have no personal experience with flying them. My
understanding is that the Tee-Dee was harder to handle, and needed
pressure feed (usually with a bladder tank), but would go like heck.

Unless you had a product engine (fuel nipple and needle valve on a big
plastic block in the back) you had either a Medallion or a Tee-Dee, you
lucky dog.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Sat, 03 Apr 2010 15:30:07 -0700, Tim Wescott
wrote:

John wrote:
On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.


Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Oops -- I left that out.

Its a reed-valve engine, built from a bucket-o-engines with a Babe-bee
case and tank, but with a two-bypass cylinder as often came on the
'product' engines that went into the ready-to-fly airplanes.

There were two rotary-valve engines: the Medallion (sport) and the
Tee-Dee (competition) engine. The Medallion had a red plastic venturi,
while the Tee-Dee had an aluminum one. I never had the bucks for such
fancy things, so I have no personal experience with flying them. My
understanding is that the Tee-Dee was harder to handle, and needed
pressure feed (usually with a bladder tank), but would go like heck.

Unless you had a product engine (fuel nipple and needle valve on a big
plastic block in the back) you had either a Medallion or a Tee-Dee, you
lucky dog.

I don't really remember, it was a LONG time ago. But from what I think
I remember all the Cox of that time were reed valve engines. All the
competition engines were two bypass, I think. I seem to remember that
some had a integral fuel tank and some were flat backs. I don't
remember how the timer worked but seem to remember that the freeflight
engines could be tanked engines and the speed guys had to run around
and locate a flat back version.There were also some baby Cox, or some
such name, that had a plastic tank, I seem to remember that weren't
very popular. To be frank I only flew 1/2A speed because if you could
build anything that flew even reasonably quick it was almost a free
trophy.

A and B speed were my specialties and I flew 1/2 A and C more because
that is what the other guys did, rather then because I really liked
it. A full bore 0.60 cu.in. engine in even a mediocre design is sort
of scary :-)

I see you talking about batteries. In those days everyone had two
lantern batteries, wired in parallel, sat in the end of the flight
box. worked with everything. I seem to remember that the Cox could
burn out the '"glowplug" if you had a brand new set of batteries. Kind
of irksome as heads cost more then glow plugs.

Cheers,

John D.
(jdslocombatgmail)

John wrote:
On Sat, 03 Apr 2010 15:30:07 -0700, Tim Wescott
wrote:

John wrote:
On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.

Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Oops -- I left that out.

Its a reed-valve engine, built from a bucket-o-engines with a Babe-bee
case and tank, but with a two-bypass cylinder as often came on the
'product' engines that went into the ready-to-fly airplanes.

There were two rotary-valve engines: the Medallion (sport) and the
Tee-Dee (competition) engine. The Medallion had a red plastic venturi,
while the Tee-Dee had an aluminum one. I never had the bucks for such
fancy things, so I have no personal experience with flying them. My
understanding is that the Tee-Dee was harder to handle, and needed
pressure feed (usually with a bladder tank), but would go like heck.

Unless you had a product engine (fuel nipple and needle valve on a big
plastic block in the back) you had either a Medallion or a Tee-Dee, you
lucky dog.

I don't really remember, it was a LONG time ago. But from what I think
I remember all the Cox of that time were reed valve engines. All the
competition engines were two bypass, I think. I seem to remember that
some had a integral fuel tank and some were flat backs. I don't
remember how the timer worked but seem to remember that the freeflight
engines could be tanked engines and the speed guys had to run around
and locate a flat back version.There were also some baby Cox, or some
such name, that had a plastic tank, I seem to remember that weren't
very popular. To be frank I only flew 1/2A speed because if you could
build anything that flew even reasonably quick it was almost a free
trophy.

A and B speed were my specialties and I flew 1/2 A and C more because
that is what the other guys did, rather then because I really liked
it. A full bore 0.60 cu.in. engine in even a mediocre design is sort
of scary :-)

I see you talking about batteries. In those days everyone had two
lantern batteries, wired in parallel, sat in the end of the flight
box. worked with everything. I seem to remember that the Cox could
burn out the '"glowplug" if you had a brand new set of batteries. Kind
of irksome as heads cost more then glow plugs.

Cheers,

John D.
(jdslocombatgmail)

Unless it was a Really Long Time Ago (before 1961) the "flat back"
engines were front rotary valve. Of course you don't have to believe it
-- there's a web page on Cox engines:
http://en.wikipedia.org/wiki/Cox_engine. Search down to "Tee Dee" or
"Medallion".

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com

On Sun, 04 Apr 2010 11:43:33 -0700, Tim Wescott
wrote:

John wrote:
On Sat, 03 Apr 2010 15:30:07 -0700, Tim Wescott
wrote:

John wrote:
On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.

Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Oops -- I left that out.

Its a reed-valve engine, built from a bucket-o-engines with a Babe-bee
case and tank, but with a two-bypass cylinder as often came on the
'product' engines that went into the ready-to-fly airplanes.

There were two rotary-valve engines: the Medallion (sport) and the
Tee-Dee (competition) engine. The Medallion had a red plastic venturi,
while the Tee-Dee had an aluminum one. I never had the bucks for such
fancy things, so I have no personal experience with flying them. My
understanding is that the Tee-Dee was harder to handle, and needed
pressure feed (usually with a bladder tank), but would go like heck.

Unless you had a product engine (fuel nipple and needle valve on a big
plastic block in the back) you had either a Medallion or a Tee-Dee, you
lucky dog.

I don't really remember, it was a LONG time ago. But from what I think
I remember all the Cox of that time were reed valve engines. All the
competition engines were two bypass, I think. I seem to remember that
some had a integral fuel tank and some were flat backs. I don't
remember how the timer worked but seem to remember that the freeflight
engines could be tanked engines and the speed guys had to run around
and locate a flat back version.There were also some baby Cox, or some
such name, that had a plastic tank, I seem to remember that weren't
very popular. To be frank I only flew 1/2A speed because if you could
build anything that flew even reasonably quick it was almost a free
trophy.

A and B speed were my specialties and I flew 1/2 A and C more because
that is what the other guys did, rather then because I really liked
it. A full bore 0.60 cu.in. engine in even a mediocre design is sort
of scary :-)

I see you talking about batteries. In those days everyone had two
lantern batteries, wired in parallel, sat in the end of the flight
box. worked with everything. I seem to remember that the Cox could
burn out the '"glowplug" if you had a brand new set of batteries. Kind
of irksome as heads cost more then glow plugs.

Cheers,

John D.
(jdslocombatgmail)

Unless it was a Really Long Time Ago (before 1961) the "flat back"
engines were front rotary valve. Of course you don't have to believe it
-- there's a web page on Cox engines:
http://en.wikipedia.org/wiki/Cox_engine. Search down to "Tee Dee" or
"Medallion".

Well, it would have been about '55 - '59 during my first tour in
Japan. From looking at the Wiki you reference the engines must have
been a Thermal Hopper as there is nothing further down the page that
looks anything like what we used.

The front induction engines came along later and as I remember weren't
particularly highly rated.

Cheers,

John D.
(jdslocombatgmail)

I used to fly the tiny ones - sub size. Internal tank on the tiny ones
since they were wire control anyway. Tire you out before it finished.
The o49 was even worse - lasted a long time.

It - some models maybe - had two spouts - on the top - in/out of the tank -
and one could put another feeder tank in-line. But I never saw one -
since most free flight were much larger and had large tanks on the balance line.

Martin

John wrote:
On Sat, 03 Apr 2010 15:30:07 -0700, Tim Wescott
wrote:

John wrote:
On Thu, 01 Apr 2010 18:24:44 -0700, Tim Wescott
wrote:

http://www.metalworking.com/dropbox/. Search on "cox_head".

Just finished running it -- ran through a whole tank of 10% nitro fuel.
I couldn't do that with the stock head; I think it just didn't have
enough compression. This head has stupid-high compression* -- it runs
better with a stack of three head gaskets than it does with none (I need
to try it with one or two).

_And_ it starts with a ni-starter -- Cox glow heads _demand_ a good dry
cell battery, and just sneer at you if you try to give them 1.2V from a
nicad.

* Note that it was built with more compression than the drawing
indicates, and wider fin spacing.

Congratulation. I don't know which model Cox you have, I used to fly
one of the tankless ones in 1/2A speed, back when they were the usual
class 1/2 A selection. Used to win a trophy with the little thing
every one in a while.
They were also commonly used in class 1/2A free flight in those days.

Oops -- I left that out.

Its a reed-valve engine, built from a bucket-o-engines with a Babe-bee
case and tank, but with a two-bypass cylinder as often came on the
'product' engines that went into the ready-to-fly airplanes.

There were two rotary-valve engines: the Medallion (sport) and the
Tee-Dee (competition) engine. The Medallion had a red plastic venturi,
while the Tee-Dee had an aluminum one. I never had the bucks for such
fancy things, so I have no personal experience with flying them. My
understanding is that the Tee-Dee was harder to handle, and needed
pressure feed (usually with a bladder tank), but would go like heck.

Unless you had a product engine (fuel nipple and needle valve on a big
plastic block in the back) you had either a Medallion or a Tee-Dee, you
lucky dog.

I don't really remember, it was a LONG time ago. But from what I think
I remember all the Cox of that time were reed valve engines. All the
competition engines were two bypass, I think. I seem to remember that
some had a integral fuel tank and some were flat backs. I don't
remember how the timer worked but seem to remember that the freeflight
engines could be tanked engines and the speed guys had to run around
and locate a flat back version.There were also some baby Cox, or some
such name, that had a plastic tank, I seem to remember that weren't
very popular. To be frank I only flew 1/2A speed because if you could
build anything that flew even reasonably quick it was almost a free
trophy.

A and B speed were my specialties and I flew 1/2 A and C more because
that is what the other guys did, rather then because I really liked
it. A full bore 0.60 cu.in. engine in even a mediocre design is sort
of scary :-)

I see you talking about batteries. In those days everyone had two
lantern batteries, wired in parallel, sat in the end of the flight
box. worked with everything. I seem to remember that the Cox could
burn out the '"glowplug" if you had a brand new set of batteries. Kind
of irksome as heads cost more then glow plugs.

Cheers,

John D.
(jdslocombatgmail)