Re: Big pop-pop engine
- Hi Dan and Jean-Yves,
Dan's comments about the effect of changes of thrust pipe length on
performance reminded me of a thread about a hotter fire a while back.
Go back to message #498 of 702 for comments by Vance Bass on an engine
that didn't run with a real hot fire and his observation to the effect
that cooling is just as important as heating. The logical conclusion
seemed to be that the best route for thrust pipes is the shortest one
for getting them into water outside the hull. In most cases, that
route would be straight down with bends in directions opposite to the
way the boat should go. old Frank
--- In firstname.lastname@example.org, "danoyes1" <danoyes1@...>
> Hi all
> wow supper cool German pop pop, that looks like a lot of thrust!
> Are your calculations affected by the length of the thrust pipe and
> momentum of water in it. while I was building the Barrel Boiler
> engine I first had the thrust pipe at 5 ft. long and the engine
> seemed to cycle a little more slowely...I think, when I cut the pipe
> down to three ft. it seemed that the cycle increased slightly while
> the volume of water expelled with each cycle decreased slightly... i
> could run a test with the 3ft pipe then attach another five ft.
> section of pipe and see if there is a change in rate.
> Also do your calculations say anything about the amount of cooling
> energy at the water end of the pipe. I have noticed that the engine
> pulses more vigorously when the water in my test tank is cool, after
> an extended run time the water in the tank will warm and begin to
> steam and it seems that the engine looses power at this point.
> thanks for the science!
> --- In email@example.com, "Jean-Yves Renaud"
> <boite.de.j-y@> wrote:
> > Hi Dan,
> > With the data of your engine I calculated the heating power. Very
> > approximately it is 170W.
> > Then I calculated the theoretical frequency which is 1Hz. As it is
> > (exactly) the value you indicated I'm very happy to get a
> > of "my" theory.
> > I don't know if we can attach a document and if yes I don't know
> how to
> > do this. If you wish to get the calculation file, just let me know.
> > Best wishes.
> > Jean-Yves
- Hi dan,
I'm presently travelling far from my pop-pop engines. The pipe of the big engine is approx 75cm long. It is going up for the first 10cm and then it is straight and slightluy inclined down. More details in a couple of weeks when I am back to my "laboratory".
> Message du 19/03/07 00:15
> De : "danoyes1" <danoyes1@...>
> A : firstname.lastname@example.org
> Copie à :
> Objet : [pop-pop-steamboats] Re: Big pop-pop engine
> Hi all
> Jean I look foreward to hearing the test results you get for your
> big drum evaporator. how long is the pulse pipe on your new engine?
> it's good to hear that it had such a powerfull thrust pulse and ran
> without incident.
> --- In email@example.com, "Slater Harrison"
> <Sharrison@...> wrote:
> > I was just looking at Dan's and Jean-Yves' pictures. Wow! I've been
> > following pop pop engines for a couple of decades and I knew of two
> > types: the diaphragm type and the coil type. I've never seen
> > like the hammer head! Where did this design come from? How long
> has it
> > been around?
> > Slater
> > -----Original Message-----
> > From: firstname.lastname@example.org
> > [mailto:email@example.com] On Behalf Of Jean-Yves
> > Renaud
> > Sent: Thursday, March 15, 2007 1:58 PM
> > To: firstname.lastname@example.org
> > Subject: [pop-pop-steamboats] Re: Big pop-pop engine
> > Hi all,
> > Up to now, my biggest pop-pop engine had a pipe of ID 10mm, and
> > engine was far from optimized because at that time I didn't know
> as much
> > as I know today. Encouraged by Dan's messages and by the pictures
> of his
> > engines, I built a big one. I wanted to call it the 4 dollar engine
> > because 2 coins of 2 Canadian $ would have been perfect to close
> > evaporator. Unfortunately (that's the appropriate word) I had only
> > coin left over from my last visit in Canada. I tried the Italian
> > coin. It fitted too...but I had only one. Therefore, as I didn't
> want to
> > be responsible of a war between Canada and Italy (with all the
> > corresponding messages on the forum!!!), I decided to build 2
> > caps by myself. (see the photo album).
> > Two hours later the engine ran at the first attempt. The
> evaporator ID
> > is 28mm and the pipe ID is 12mm. The engine seems very powerful.
> > water level in my (small) test tank (approx 15cm x 30cm) was 30mm
> > the top, but the waves succeeded to flood my work bench.
> > When I have time (i.e. probably not before next month) I will test
> > engine with appropriate measuring instruments and I'll let you
> > Jean-Yves