My bent Chinese engine started yesterday!

[Johansson]

Hi there!

A few weeks ago I got an offer I couldn´t refuse, a friend of my father was working on the coolant system at the local powerplant and asked me if I wanted a bunch of stainless pipes and bends.

-"Hmm, well yes I do!" I replied...

Inspired by the nice look of Hinote´s engines I threw one together in a couple of evenings and started it yesterday, even though the propane injector was the crudest one ever built it started at an instant. I didn´t even have to change the position of the injector, guess I was lucky.

Today I will make a better injector and try to get a thrust reading from it, my fishing scale can only handle 10 kg so I might have to get a stronger scale if it bottoms out...

//Anders

[Johansson]

Made a better injector with a vapour coil around the tailpipe today and ran it a few times, it runs quite rough with sudden flameouts and almost no throttle range. I tried to run it on liquid propane and it became clear that it needs more fuel than the vapour can provide, but it is still not running smooth.

Any ideas of what the problem can be?

//Anders

Edit: I know that the coil should be closer to the CC to absorb more heat, but it should still run on vapour...

Edit 2: It runs fine now, just had to open up the holes in the injector a bit. It throttles nicely all the way up to rich extinction on liquid and blowed all gravel in front of it onto my lawn...

[Mike Everman]

Nice, Anders!

[hinote]

Inspired by the nice look of Hinote´s engines I threw one together in a couple of evenings and started it yesterday, even though the propane injector was the crudest one ever built it started at an instant. I didn´t even have to change the position of the injector, guess I was lucky.

Nice looking motor! (but I guess I'm biased).

Can you tell us the diameter of the combustion chamber, and the tailpipe final section?

[Johansson]

Thanks!

The 70mm and 125mm tubing is 1.5mm thick SS while the cones are made from 1mm sheet SS, so that is the reason why the heating pattern looks a little strange. It is not directly flight-weight but since the engine won´t propel anything it doesen´t bother me.

//Anders

Edit: I felt that I had to point out that it is the INNER diameters.

[larry cottrill]

Nice one, Anders - congratulations!

L Cottrill

[Johansson]

Thanks for the kind words, I am glad that it works as good as it does since I got the numbers from AutoCAD by the fault-proof method of drawing something that looks like it could run and then measuring the parts... ;-)

Are there anyone that can check what frequency it runs at? I have a program for that but it has expired.

//Anders

[Eric]

Was that video from before you opened up the fuel injector?

Definately sounds like a good start, but you will definately be able to get more power and more smooth running out of it.

Eric

[Johansson]

Yes, it was from the first start, before I even tried to find the best spot for the injector.

I showed the engine for a couple of people yesterday and ran it on liquid propane, and found that the heating coil must be moved closer to the CC since it froze up all the way to the intake. If I run the engine for a while with the tank standing and tilt it when the engine is hot then it works better, but it would be more convenient to be able to start it on liquid.

It was by the way the stupidest place to fit the coil, the air pulled up the exhaust chills the last 20 cm of the tailpipe so it is not even discoloured. I put it there so it would be easy to remove while adjusting the injector...

//Anders

[Johansson]

I tried to measure the thrust today with my 10 kg scale. Since I had to weigh down the stand to keep it from tipping over and since the ground was not exactly flat the readings might be a bit low, but a rough reading is better than no reading at all...

The engine pulled 6.5 kg on gasseous propane but didn´t run smooth because the propane injector was vibrating so much, I must fasten it better before the next test. After a while I inverted the bottle and ran it on liquid, even the lowest setting on the bottle valve bottomed out the scale at 10 kg so when I get a better scale I should be getting readings of >15 kg thrust. Due to the vibrating injector it was hard to get into lock-up at full throttle but when it finally did the trust was impressive. The front of the stand lifted from the ground despite the weight of a car battery and the rope it was tied down with was stretched like a bow-string.

I don´t know how much more I can run the engine this weekend, people 5 km away have heard some loud roarings even though they were sitting indoors so I think that I will keep a low profile for a while...

//Anders

[Fricke]

Well after seeing Johanssons little engine...
I had to try to make one myself... *grin*




It´s almost an identcal twin to Anders, but I´ve used 73 mm tube...
And I´m running it on liquid fuel - JET A1... No propane!!

It starts fine with the help of a small vaccum cleaner.

It needs some minor adjustments in the fueling department. Then it should produce more noise and thrust... =)

[larry cottrill]

Fricke -

Man, that's a nice one, too! I'm bothered a little bit by the tubular "block" between the chamber and tailpipe - is that a sliding fit at one side or the other?

Good work, especially the liquid fueling part! Please provide more information on how you rigged that, if you don't mind sharing the info.

L Cottrill

[Fricke]

Man, that's a nice one, too! I'm bothered a little bit by the tubular "block" between the chamber and tailpipe - is that a sliding fit at one side or the other?

Good work, especially the liquid fueling part! Please provide more information on how you rigged that, if you don't mind sharing the info.

Hi Larry!

Thank You!

That "block" was only temporary, it´s replaced by a smaller tube that is welded on both the chamber and tailpipe. Mainly because the whole engine was only made as an experiment, and not intended to last long. So if it breaks later I don´t mind.

I´ll write You a PM later about the fuelsystem.

[Eric]

Nice job. Especially nice job on the flare. Most flares you see are too small. This style engine really benifits from a good strong flare. Did you do it by hand or use a press?

I think the welding in place was Larrys concern. With thermal expansion the engine will want to expand. Typically with a support bracket type thing like that you should only weld it to one or the other, so that it will be held in place by one but allow the other to slide back and forth while still supporting the weight.

Just a suggestion to anyone else who might want to build from the plans posted and want the max potential performance, if the tailpipe is made a little longer, so the expansion cone section is as long as the expanded part, and have about 11" of 7.5" dia tubing at the end, and with a slightly longer intake, the engine should be capable of producing around 60 lbs thrust easy with extremely good fuel efficiency.

If the combustion chamber were larger as well It would be more along 70 by ordinary means.

Eric

[leo]

Nice build both of you.
Why do you cal it a bent Chinese , to me its more a bent Escopetta.