- Hi Dan, I don t say the water temp has no influence at all, but its influence is negligible for our application. When your engine stopped pulsing you removedMessage 1 of 37 , Mar 6 12:59 AMView Source
I don't say the water temp has no influence at all, but its influence is negligible for our application.
When your engine stopped pulsing you removed the heat and a minute or so later it pulsed several times and then stopped again This is typical of a too powerful heating.
In the video of Richard there is a clear section which allows to seeing the water steam interface. It also allows to thermally isolating the evaporator from the pipe. I built many engines with a full transparent plastic tube and a few with Pyrex glass. Guus, Loïc, George, Christophe built full glass engines to see inside. All these engines worked. It doesn't prove that thermal isolation is required, but at least it means that a good thermal conductivity of the pipe is not needed.
Coming back to Richard's video. Richard uses diaphragm type engines which are less efficient and very likely less sensitive to overheating so long as they are pulsing. According to what I know today I think that Richard's engine would be more powerful (though they are powerful) if the tubes were longer and inclined. As they are practically horizontal I cannot say if the liquid water enters into the boiler.
With plastic or glass tubes we had the opportunity to see the water/steam interface. Sometimes the engine stats pulsing with the interface close to the evaporator (or boiler, or drum. There is no perfect word for it), sometimes down to 1 ft below in the pipe. Difficult to know why. In that latter case, generally the interface climbs up (let say in a minute) to find its right place close to the top of the pipe. Then, (if the heating power is correct) the mean position of the interface climbs down very slowly while the stroke increases. It could take hours. (See "Thrust versus time" on www.eclecticspace.net.) And the final best situation is when the mean position is at the middle of the pipe, and the stroke is the full pipe length. Getting this could require hours, but you can save time by using Slater's procedure: "Fill the engine, shake it, empty it, and then fill it partly". You will see that it is more powerful with air inside.
I used another mean when testing some engines. The engines were filled and started as usual, and then with a syringe and a soft plastic tube I introduced a well know quantity of air to increase the delivered power. See "Gas in a pop-pop engine" on www.eclecticspace.net.
Note: My reports should be slightly modified to take into account what I discovered since I wrote them, but most of their content is valid. (When I have time ).
Please let me know the result of your experiments. Good luck!
- 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 isMessage 37 of 37 , Mar 21 11:19 AMView SourceHi 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