Can't find blue shim sheets, but got strips, so...

[skyfrog]

I have difficulty in obtaining materials of making the petal valve. Yes we are newly industrialized country, we manufacture alot of products for exporting but people here don't seem to home-build things, so material retailers don't provide diversified options. (Maybe we do have, the only reason I can't get it is because I'm a lousy buyer).

I Got some 0.006" thick spring coils from junkyard, which was made of stainless spring strips 10mm wide. Straight strips were recovered by annealing the coils to remove the residual bending stress, I hope this process wouldn't scacrifice too much of its elasticity. Reed valve design was changed in accordance.

I hope this works.

[skyfrog]

One more thing, blame the material substitude, fueling from the center of the valve plate has been sacrificed too. The fueling sprayer has been moved to C.C. body.

[larry cottrill]

Skyfrog -

Nice try, but, like many simple solutions, there are some problems lurking. I don't know how serious these will be, and I think you might as well try this, but I doubt that it will work as well as you might expect.

The first problem is that your valves will have three different degrees of flexibility. The outermost valve piece will bend close to the center bolt, and be highly flexible. The middle piece will be constrained by the only slightly bent center section of the outer piece, and will be stiffer because of the restriction to how it can bend. The innermost one will be constrained even more, by the two on top of it. A good domed retainer would help, but would not alleviate the problem entirely since even that will not influence the three strips equally.

Another problem, perhaps not as severe, is that it will be harder for the outermost valve to seal properly against the valve plate [assuming that the valve plate is flat, as usual]. The innermost valve will have a near-perfect fit, and the middle one somewhere in between. Yes, it's just a few thousandths of an inch, but a little leakage can have a big effect, especially on good starting.

Now, having said all that, I think you should go ahead and try it, and report back to us on what happens. For one thing, I could be wrong -- maybe the effects stated aren't as important as I think they'll be. For another thing, doing this doesn't keep you from coming up with an etched or otherwise custom-cut single-piece valve later, and the scheme you show is so simple that not much effort is wasted even if it fails. So, why not? Go for it!

L Cottrill

[skyfrog]

The first problem is that your valves will have three different degrees of flexibility. The outermost valve piece will bend close to the center bolt, and be highly flexible. The middle piece will be constrained by the only slightly bent center section of the outer piece, and will be stiffer because of the restriction to how it can bend. The innermost one will be constrained even more, by the two on top of it. A good domed retainer would help, but would not alleviate the problem entirely since even that will not influence the three strips equally.

Another problem, perhaps not as severe, is that it will be harder for the outermost valve to seal properly against the valve plate [assuming that the valve plate is flat, as usual]. The innermost valve will have a near-perfect fit, and the middle one somewhere in between. Yes, it's just a few thousandths of an inch, but a little leakage can have a big effect, especially on good starting.

Thanks for your comments, they are so precise as to right on the target.

I have some solid mechanics background, so I fully understand what you 're talking about. These strips not only have different flexibility, but also have different natural frequencies.

For unequal flexibility problem, and sealing problem, maybe I can do some tricks(or magic) to the retainer and the strips, so that the problems can just go away. Thanks to the fact that the misalignment is only just a few thousandths of an inch.

Yes, I'll go for it and get the results posted.

Cheers !

[steve]

you problems sound almost exactly like the ones I encountered when I built my first engine. my solution was to have multiple valves rather then just one big one with many petals. Also keep in mind that the pattern of the intake holes does not need to be circular; I used a rectangular layout for my engine and it worked fine. one of the major advantages of this design is that it is very easy to make a new set of valves in just a few minutes. I also relocated my fuel injector to the body of the engine rather then through the head.

[Mark]

What I did was just cut out a petal and drew a line around it with a marker over some spring steel. Then I ground the same form against a spinning grinding wheel to shape it. I layed the 9 petals out and then gently tightened the valve retainer to lock them down against the valve plate once they were positioned. That way they all lay equally flat unlike the stacked design you are toying with. The scan is a little faint, some of the bluing wore off some of the reeds so they don't show up very well.
It's a crude but functional method, if a valve wears out, you only have to make a small single petal and tuck it under the retainer. There is my Dynajet red head on the left in the photo. You can see where I leaned out the pipe engine one time, causing the blue tint on the retainer from over heating, but if you don't starve the engine for fuel, you could probably run your pulsejet at least a few hundred degrees cooler using methanol, instead of the hotter gasoline or propane. In fact I have run this pipe engine a dull red hot and the head, ice cold, from the intake and evaporation of methanol in the throat.
Mark

[skyfrog]

you problems sound almost exactly like the ones I encountered when I built my first engine. my solution was to have multiple valves rather then just one big one with many petals. Also keep in mind that the pattern of the intake holes does not need to be circular; I used a rectangular layout for my engine and it worked fine. one of the major advantages of this design is that it is very easy to make a new set of valves in just a few minutes. I also relocated my fuel injector to the body of the engine rather then through the head.

Nice alternative, Steve., and thanks for the sharing of your idea.

But how did you keep the strips from rotating, tighten the bolts did the work ?

[Mike Everman]

Very nice work, Steve, and beautiful photos. I am going to buy Mark a digital camera soon. ;-)

[skyfrog]

What I did was just cut out a petal and drew a line around it with a marker over some spring steel. Then I ground the same form against a spinning grinding wheel to shape it. I layed the 9 petals out and then gently tightened the valve retainer to lock them down against the valve plate once they were positioned. That way they all lay equally flat unlike the stacked design you are toying with. The scan is a little faint, some of the bluing wore off some of the reeds so they don't show up very well.
It's a crude but functional method, if a valve wears out, you only have to make a small single petal and tuck it under the retainer. There is my Dynajet red head on the left in the photo. You can see where I leaned out the pipe engine one time, causing the blue tint on the retainer from over heating, but if you don't starve the engine for fuel, you could probably run your pulsejet at least a few hundred degrees cooler using methanol, instead of the hotter gasoline or propane. In fact I have run this pipe engine a dull red hot and the head, ice cold, from the intake and evaporation of methanol in the throat.
Mark

Thanks for your suggestions and idea sharing, Mark.

I had went through your approach in the very beginning too, but these strips are really thin, seems like nothing could hold them tight, this made me decided to bolt them well. I have plenty of those 10mm wide strips in stock, so I'll probably stick to this design for a while, if it works.

[Mark]

It's really no different whether you bolt them down your way or bolt them down my way, once the retainer is pressed down from the bolt, it is in effect a bolt with a washer.
The ten petals of the Dynajet are just one single reed, one single part, but they could just as easily be 10 single petals for the retainer holds the petals down not at the center but further out on the reed. The Japanese copy of a Dynajet uses 2 half reeds that look like you cut a Dynajet reed down the middle, I guess if a reed goes bad on this design, you only have to replace the half of petal that is bad.
Here's another view of my 9 single petals used in the smaller valve and a larger, single, one piece flower petal reed with 18 petals made with a dremel.
Mark

[Mark]

A view of the three steps from a disk of blue spring steel to reed. Pictured are 3 disks of .006ths reed material. An index head was used to rotate the disk and then a dremel cut the lines and with another bit, ground and rounded the tips. After cutting, they were gently sanded with fine sand paper to remove the rough edges or burrs.

[larry cottrill]

Steve -

Yes, that's a beautiful example of a valved engine, and a nice use of available materials for the valving. Very sharp work!

The use of flat straight pieces reminds me of the discussion we had on the old forums as to using steel tape rule material [you know, the thing clipped to your belt that lets you measure anything up to ten feet]. The interesting thing about such material is that it is permanently curved slightly, so there is an 'artificial stiffness' that tries to spring it out straight. Here's one amusing concept I had for a tape-valve engine front end. As you'll see, this is 'simplicity itself' as I always say ;-)

L Cottrill

[Mark]

And here's Larry's artistic lines describing the workings of the valve I made from simple parts.
Mark

[skyfrog]

Really grateful for so many interesting ideas, guys.

I got from motorcycle store a NGK C7HSA spark plug, The thread is M10, Pitch 1.0mm, it took me quite a while to find a nut matching this plug, phewww.
what I am going to do is, to drill a 10mm diameter hole on the C.C. body, then weld the nut onto it, so I can screw this spark plug into and tighten it. I haven't get a ignition coil yet. Motocycle spark plug, so I'll get a motorcycle coil too.

Any suggestion ?

[mk]

I haven't get a ignition coil yet. Motocycle spark plug, so I'll get a motorcycle coil too.

Any suggestion ?

A special coil-spark plug combination isn't needed. But a motorcycle coil is good. You just need a switch (or a relay if you are good in electrical stuff), a 12V (=) power supply, maybe a battery, and a ~0.22 10e-6F capacitor.
Connect the switch, the coil and the power supply to a closed "circle". Finally place the capacitor (reduces self induktion sparks in the switch) parallel to the switch.

You should get a nice spark at every switch then.
Note: A relay would do the switching process for you, maybe much faster, too.