Tom,
I have been doubling up with photos and had two folders. There were
already some in a folder entitled Another Stirling Outboard in Tasmania, which I
put up in May. This folder name was not very helpful. I have tried to change
the name but not succeeded, Could you change it for me to read "Harry's
outboard, 4DA 800". This should make it easier for others to find it and relate
it to our e-mails. The folder named "4 cylinder Stirling outboard" is empty.
I would like this one deleted, thanks.
Harry.

----- Original Message -----
From: Tom Gentry
To: sesusa@yahoogroups.com
Sent: Wednesday, June 10, 2009 5:22 AM
Subject: [sesusa] Harry's outboard (was ST-5 etc.)





Harry,

Please forgive me for being a bit thick but does that mean that each PAIR (1
hot and 1 cold) have a swept volume of 200cc? That would be 800cc/4
pairs=200cc/pair.

These are Siemens double acting cylinders correct?

Or are there just 2 pairs of cylinders, making up 2 gas circuits?

It is sort of important that I get this right. So please help me out here.

Tom

--- In sesusa@yahoogroups.com, "Harry Diers " <harrydiers@...> wrote:
>
> Hello Tom,
>
> Sorry for the delay, I have been "off line" for a while. Here are some
specifications for the engine. Net swept volume of each cylinder is 207cc. 800,
(or 828cc) is the total effective swept volume of the 4 cylinders. The working
gas is air and the charge pressure is up to 3 bar cold (not running).
>
>
>
> SPECIFICATIONS for one cylinder.
>
> Bore 7cm, Stroke 4cm, Net swept volume 207cc, Max hot volume 147cc, Working
pressure (air) 3 bar, Max temp 600 deg C. Min temp 30deg C
>
> PISTON AREA; Top side ( expansion ) 38.5 cm2 Under side (compression) 33.6
cm2 Under side is less because of the cross sectional area of the piston rod.
>
> HEATER;
>
> Slot length 7cm Slot width .15cm, Cross sectional area 4.2cm2, Dead volume
29.4cc, Heat transfer area 261cm2.
>
>
>
> REGENERATOR;
>
> Length 5cm, Average width .6cm, Cross sectional area 16cm2, Total volume
80cc, Dead volume 70cc.
>
>
>
>
> COOLER;
>
> Length 7cm, Slot Width .1cm, Cross sectional area 2.8cm2, Dead volume
19.7cc, Surface area 593cm2.
>
>
> Transfer duct dead volume, 5cc.
>
> Totals;
>
> Swept Volume 207cc
>
> Dead Volume 124cc
>
> Regards, Harry.
>
>
>
> ----- Original Message -----
> From: Tom Gentry
> To: sesusa@yahoogroups.com
> Sent: Sunday, June 07, 2009 2:20 AM
> Subject: [sesusa] Re: ST- 5 and 4 DA 800
>
>
>
>
>
> Harry,
>
> Just a few comments before I start plugging in numbers.
>
> Due to the fact that the Nt ratio is less than 3.0, I calculate about 2.71,
the Beal Equation is going to be off by 3.00-2.71/3.00%. To correct for this, I
believe we can perhaps use the West Equation which has a term for the
temperatures albeit in the form of efficiency a la Carnot.
>
> I will look at the scaling functions to see if the efficiency is used
anywhere.
>
> Questions:is 800cc = Vswept ot displacement of each cylinder?
> is gas Nitogen (air)?
> What is the charged pressure (nor running, cold)?
>
> Thanks,
>
> Tom
>
> --- In sesusa@yahoogroups.com, "bernhard" <baernibaer@> wrote:
> >
> > Hello Harry,
> >
> > --- In sesusa@yahoogroups.com, "Harry Diers " <harrydiers@> wrote:
> > >
> > > Hello Tom,
> > > Thanks for the compliment it is very much appreciated.
> > > The strength of the arms was designed to take 1.5 Kw. At this power I
calculated about 70 Kg max load on each piston. That meant that if I locked the
mechanism so it could not move each arm would need to support my weight if I
stood on it. It did that easily. The tops of the arms are reinforced with a thin
steel plate under tension. The rest is aluminum accept for the pin (shown in one
photo), which is steel. A large amount of work went into this mechanism. The
universal cross in the centre of the arms still has the original needle races on
it. They do not like the end loading they get for part of the cycle and so need
to be replaced with deep groove ball races. Because of the work involved in
fitting this type of bearings I used the needle races just to get the engine
going in the time available. This is a first time for this layout and I just
wanted to see how it would work. It is very good and could be built to take
whatever power you like. And I don't need a pressurized crankcase! The piston
rod seals have to hold the pressurization and there are 4 of them instead of one
shaft seal so leakage might be up a bit. When I first tried them they held
pressure for quite a while and they had not been run in.
> > > I am happy to consider other gas circuit configurations. Getting the gas
circuit right is the hardest part. The original design parameters were; Light
weight, simple unfinned heat exchangers, (unfinned for simplicity and to avoid
the plenun and its dead volume at the base of the cooler, I would like to copy
Andy Ross' furnace brazed internal heater fining but have not found anyone to
help with that).
> > > Also lots of cooling as I have found just how much difference this
makes. The Rinia was chosen for smooth torque at low revs hopefully reducing
noise as well and giving larger heating and cooling surface area for the same
size engine. I would like the design to be as simple as possible so other people
might be interested in building one. The pin drive may not look simple but it is
really once you figure it out. ( A 4 cylinder engine with only 6 moving parts).
> > > The design also had to allow pressurization. Not having a pressurized
crankcase greatly reduces the weight. For a couple of years I had been designing
around a pressurized crankcase until I read Bob Sier's article in Stirling News
where he said his reason for his choice of design was to avoid this. Thinking
about this I realized I didn't need one either. What a wonderful realization
that was. It means that the pin drive arms have to cope with more load but I can
get rid of the heavy case. At this stage I am planning not to have a flywheel.
The pin drive box is the support for the engine and so the only way a flywheel
could be fitted would be to use a long small diameter tube around the drive
shaft in the outboard leg.
> > > For my application the engine must not weigh more than 15Kg complete. It
is close to that already without the auxiliaries. A new burner is almost
finished saving half a Kilogram and hopefully giving a better fire.
> > > There is one experience I must tell you about. when the engine was first
run you could hear the water sloshing inside. After a very short run I turned
off the heater, the engine stopped and I went outside to turn off the cooling
water. I was surprised to hear the engine start and run a few turns. I came back
in and as I was looking at it it started again for 2 or 3 turns. Perhaps part
steam and part stirling, very strange.
> >
> > Strange, but interesting - maybe combinations You like?
> >
> > Partly Stirling/Rankine system:
> >
http://www.sae.org/servlets/productDetail?PROD_TYP=PAPER&PROD_CD=1999-01-2502
> >
> > seperate systems for higher overall efficiency:
> > http://www.rgpsystems.com/solutions.html
> >
> > Thanks for the hint about the possibility for the unpressurized crankcase
(no buffer space losses also - yeah that's great!).
> > You are inspiring my research, Regards,
> > bernhard
> >
>
>
>
>
>
> [Non-text portions of this message have been removed]
>





[Non-text portions of this message have been removed]