Newbie valves - please be gentle!

[m1tch]

Hi everyone, this is my first post up on the forum and im brand new to pulse jet, I have been digging around quite a bit and can see the benifits of having the traditional valved pulse jet

Few things about me:

I havn't ever built a pulsejet before
I can't weld - yet lol
I have very limited tools
Im ok with the physics of the pulsejet, just need help/tips with building things

I have read about different sorts of valves, mainly the petal and the reed valves that can last between 15 seconds and 30 minutes lol Please remember that im having a go at this to build confidence with making things

I had a look at that 'no weld' pulsejet and will try and make one as my first attempt at a pulse jet, watched some of the free video and tried to gather as many plans that I could on it. I can see its using a petal valve with a retainer to ensure that the petals don't get fatigued too quickly and that it was basically a petal valve with a bottle and some pipes

I just need to ask about this:

Whats the best way to make the valves? should I try making a petal or make a grid/reed sort? I can understand how the petal valve works as its just bolted though the middle, but I can't quite see how the other sort works - guessing its secured in the middle of the A frame?

I have read about electro etching a petal, but I don't have any acid or the kind of tools to get something like that - does it need to be a petal or can it just be a disk of spring steel with cuts down to the centre to cover the holes?

Sorry for such a noob post, but im really interested in all this

Thanks for any replys!

[vturbine]

Well if you have your heart set on a valved pulsejet, ignore the following:

valveless pulsejet made from plumbing fittings and pipe nipples -- no welding or machining:

viewtopic.php?t=1643&postdays=0&postorder=asc&start=0

And, yes some of those fittings are hard to find at local plumbing outlets, but I found this here:

http://www.plumbingfittingsdirect.com/black1/60600.html

[WebPilot]

Hi m1tch and welcome.

A lot of your questions have been answered already on Bruce's site, in particular, his
The Pulsejet Engine FAQ.

I know you can 'coax' the thin metal into shape with a Dremel and cut-off wheel. It just takes time. The valve can be petal, triangular or rectangular in shape.

[m1tch]

Thanks for all the help guys I will definatly look into both designs, am I correct in saying that the valved pulsejet is able to produe more thrust in a smaller package?

Is anyone here from the UK at all?

[m1tch]

Where can I get spring steel from? I have checked online and it seems quite a specilist metal lol

also are there any off the shelf items I can use/have been used?

[GRIM]

Hi M1tch , youre in the uk ? if so try
http://www.buckandhickman.com/ They got banches all over
you would be looking for blue tempered shimsteel ,
Hope this helps
G

[m1tch]

Thanks Grim thats awesome! I Might actually be able to make a valved pulsejet now lol, I found some steel ducting reducers, so if I find an end cap for those I can just put holes in it and make some valves from the steel

Are the smaller ones harder to start, I found some ducted that goes from 100mm>80mm, would that be too large for my first pulse jet?

[James OS]

Hello M1tch
I'm from the UK too.
I'm in a similar position - i've only got simple hand tools and no welding gear.

My no weld pulsejet is almost finished - but i'm guessing its going to take alot of tweaking before it actually runs.
I got 0.006" stainless shim steel and some mild steel tubing from metal supermarkets - a really useful supplier with no minimum order. However- shim steel is pretty expensive there and when i got mine they didn't have a whole lot of it (luckily the guy lost the exact price for shim steel so i got a small sheet for £4). I did see an american supplier who does seem to deliver small quantities of metal called mc master-carr - you could check their website too.

Keep posting to say how you get along - i'd be interested to know how anyone else has gone about making and running one of these no weld engines.

So far i've encountered plenty of small and pointless problems that shouldn't be there - like connecting a hose to a tyre for compressed air, or connecting up a supply of calor gas to the engine, and finding a drill bit to drill holes in the valve plate with only a handheld power drill (i ended up using one of those cheap flat drill bits designed for wood... took me ages to drill the plate)

[m1tch]

Hello M1tch
I'm from the UK too.
I'm in a similar position - i've only got simple hand tools and no welding gear.

My no weld pulsejet is almost finished - but i'm guessing its going to take alot of tweaking before it actually runs.
I got 0.006" stainless shim steel and some mild steel tubing from metal supermarkets - a really useful supplier with no minimum order. However- shim steel is pretty expensive there and when i got mine they didn't have a whole lot of it (luckily the guy lost the exact price for shim steel so i got a small sheet for £4). I did see an american supplier who does seem to deliver small quantities of metal called mc master-carr - you could check their website too.

Keep posting to say how you get along - i'd be interested to know how anyone else has gone about making and running one of these no weld engines.

So far i've encountered plenty of small and pointless problems that shouldn't be there - like connecting a hose to a tyre for compressed air, or connecting up a supply of calor gas to the engine, and finding a drill bit to drill holes in the valve plate with only a handheld power drill (i ended up using one of those cheap flat drill bits designed for wood... took me ages to drill the plate)

Where abouts did you find a metal supermarket lol another member posted up on this thread showing an online one for spring steel

What shape is your valve? are you going for a petal one? how did you get that cut out? would scissors do it lol

[James OS]

Metal Supermarkets is the name of the supplier - their website is www.metalsupermarkets.com. I found an outlet not too far from where i live in some industrial park - check on the website or google maps to find one near you - there should be a few more here in Britain.

My valve is a regular petal valve - 12 petals radiating from a central hole (making that hole was another annoying problem). I spent a long time looking for cheap ways of making the valve - at first i thought i could do it with tin snips or scissors. From what i've heard, though, this won't work as it bends the steel and it's very difficult to cut out the right shape.

Electrochemical etching at first seemed a good idea - there's a pdf on this at http://www.aardvark.co.nz/pjet/valvelife.shtml
However, i had an old sealed lead acid car battery but no battery charger (another pointless problem). These cost like £20 minimum and there was no guarantee that the battery would work at all.

I ended up investing in a dremel - expensive at £40 but my dad wanted it for other applications, so we bought it from dremel direct.

[m1tch]

Ah ok cool, I will have a look, it looks like the nearest one is somewhere in London lol

Yeah I checked out the electro etching technique, but it looks a bit complex and as you say, it might not even work lol I will check if we have a dremel kind of thing somewhere in the garage.

What size is yours? what did you use for the body etc? So far I am planning on using these bits:

Long tube from a local supplier for the tail piece
Ducting reducer - managed to find some 100 to 80 mm or 125 to 80mm, its apparently 0.8mm thick mild steel (is that ok?)
Duct cap to put on the end of the reducer - still looking for that lol

I then plan to make a hole for the bolt to go though the valve and of course make the holes for the valves as well

What is best for that washer behind the valve to stop it bending too much? instead of a nice machine bit of aluminium, would some washers built up be ok?

Also with fueling - would it be ok to run the copper tube with the propane down the exhaust tube so I don't need to make even more holes lol or will that heat up too much and rupture?

[vturbine]

I tried the electro etching technique many years ago, and it seemed to work well for very thin materials. Somewhat thicker sheet pitted at the etch , naturally

I used a small battery charger, but according to Bruce Simpson on the site you referenced, you can use a single car or motorcycle battery as well.

The only "chemical" I used was table salt. I simply painted the blank with spray lacquer, as well -- not automotive undercoater. I didn't "pickle" the part beforehand in sulfuric acid. Just cleaned it well. It wasn't "complicated at all, and it worked.

The true spring materials are hard, and won't respond well (or at all) to conventional metal drills, etc. They can however be ground by abrasives, so you can cut them with Dremel tools as has been mentioned before. Diamond bits, will cut them as well, of course. Go easy -- local heating, however can destroy the temper.

I'm not sure whether stainless shim stock is suitable for reed valves (blue spring steel is usually used) -- others more knowledgeable can comment and correct me on that.

Good Luck!

[m1tch]

I tried the electro etching technique many years ago, and it seemed to work well for very thin materials. Somewhat thicker sheet pitted at the etch , naturally

I used a small battery charger, but according to Bruce Simpson on the site you referenced, you can use a single car or motorcycle battery as well.

The only "chemical" I used was table salt. I simply painted the blank with spray lacquer, as well -- not automotive undercoater. I didn't "pickle" the part beforehand in sulfuric acid. Just cleaned it well. It wasn't "complicated at all, and it worked.

The true spring materials are hard, and won't respond well (or at all) to conventional metal drills, etc. They can however be ground by abrasives, so you can cut them with Dremel tools as has been mentioned before. Diamond bits, will cut them as well, of course.

I'm not sure whether stainless shim stock is suitable for reed valves (blue spring steel is usually used) -- others more knowledgeable can comment and correct me on that.

Good Luck!

I think on that metalsupermarket site there was the option for shim stock, that then went over to blue steel, so I clicked on that lol can anyone give me a ball park figure of how much a sheet costs and indeed the sort of sizes people usually buy?

[vturbine]

I think on that metalsupermarket site there was the option for shim stock, that then went over to blue steel, so I clicked on that lol can anyone give me a ball park figure of how much a sheet costs and indeed the sort of sizes people usually buy?

If I were you, and wanted to set off into untested waters, I'd download the free plans for many of the reed valve jets listed in these forums, and look at the dimensions of the designed valves. That should give you a ballpark for experimenting on your own. You will eventually stumble into the issues of longevity and resonance and hopefully read Webpilot's analysis of a strip valve with fresh interest when things don't work out as they should, and in the interest of learning more. It's all learning.

Ideally, there would be a weldless, machineless, valved engine plan with complete instructions and materials list for you to follow folr high liklihood of success. But I don't think there is such a thing. Maybe someone has a suggestion of something close....?

[Tim36]

I spent ages trying to get the valves in my pulse jet right. The valves I am using now are made from .006" feeler strips. I used the dremel to cut the valves almost to size, and then finished them on a fine file to prevent burring and all that stuff that makes them leak. When you drill the holes in the valve plate, don't remove the burs with a bigger drill bit... One of many learning mistakes Surface the burs off with some really fine sandpaper on a piece of glass or something like that. I could never get the valves to last more than a minute, until I stuffed one lot up and ended up only having .8 mm overlap on each side of the valve holes. Those ones have lasted a total of about 40 minutes, spaced over about 5 runs. It's all about learning...