FWE III Pulse Jet kit Construction

[Dang911]

I am fortunate to be the first testing out a FWE III Pulse Jet kit.  The kit was focused on the concept of no/little fabrication, rather then no weld.  If you can't weld, there are many places which can assists you in that, more so then fabrication.  Anyhow, here is where I will document the build with my thoughts and illustrations. 

Today I got the kit in the mail (a great gift for the holidays for all those people who are difficulty to shop for, hehe).  I have posted pictures of what I got, and then what I needed to buy to complete the kit.

[Bruno Ogorelec]

Looks great! Now, how about some realistic pricing? How much would this kit have to cost to be made available on the market?

[Dang911]

I don't know at this point..... What I will tell you is that after taking a closer look at the kit, it looks like it will go together in only a couple of hours. That would definitely be good for a noob, which I semi consider myself.

Once it runs, I will have had the full experience. Then it will be easier to judge a price.

If everything hypothetically works like I have just described, I don't see any reason why these kits couldn't be sold for $90+. It beats buying a dynajet on ebay for $300, plus you can tweak it yourself, and actually partake in building it, a learning experience for someone who wants to continue building pulse jets.

[larry cottrill]

I have told Dang911 that the only comments I would make on this thread are responses to problems with the kit or instructions. He has posed this question, showing that I have not explained something quite clearly enough:

One question though, could you clarify the position of the fuel/air tube? From what I understand, it needs to be centered in the intake, and the "super complex" tool is for?........ I like the smell of the tool, strawberry maybe?

Do I push the fuel/air tube in it as far as it will let me go before the bend in the tube stops, hitting the engine?

This is somewhat hard to describe properly; in a finished set of instructions, it would be made clear by one or more closeup photos of the intake area. For now, I would add the following paragraphs at the beginning of the Starting Air / Fuel Tube Welding instructions:

The final major step is attachment of the starting air / fuel tube assembly to the front end assembly. What we need to end up with is ALL of the following: (a) The outlet nozzle of the starting air tube (steel) 1/2 to 5/8 inch (13 - 16 mm) AFT OF (behind) the intake flare; (b) The outlet nozzle of the starting air tube precisely centered over the engine centerline; and (c) The FORWARD END of the fuel pipe (copper) about 3/4 of the way into the length of the intake and precisely centered in the intake cross-sectional area. When finished, there should be 13 to 16 mm of the fuel pipe visible aft of the intake flare, as seen from either side.

Position of the starting air tube nozzle will be secured by carefully positioning the nozzle end and then welding the lower section of the air tube to the mounting rings located on the left side engine mount lug. After this is in place, the position of the end of the fuel pipe will be set by adjusting with the special tool provided. This will be done by gently prying against the intake flare in the desired direction, with the pipe centered in the end groove of the tool.

(I think that one was strawberry-raspberry ;-)

L Cottrill

[Dang911]

Ok Folks, here we go with the actual construction.......

After being provided with basic guide lines of how to put it together, I am going to write how I actually did it.

1.

~ Using the blueprint provided, I started by marking a center line on the wooden base (MDF board). Using the center line, I then drew out the rest of the lines, and center punched where the mounting holes for the front end assembly and exhaust tube support bracket should go.

~ Satisfied with there placement, I used a drill press to accurately drill the 3/16" holes.

~ For mounting I planed on uses nuts and bolts NOT wood screws, so to prevent the nuts form sticking out on the bottom, I made countersunk holes (1/8" deep) on the bottom of the wood board.

[Dang911]

2.

~ I started off by mounting the font end assembly onto the wood base.

~ Using the 1.25" OD antenna mast tubing, I cut a 17" section (mid section because tube has a channel at either end).

~ Flare the exhaust end of the tube. This can be done several ways, but I find the easiest is to use a big pair of pliers and bend out the wall of the pipe, a little bit a time. You can also tap the pipe onto a large steel ball or cone, just make sure not to bend the pipe, or mess up the other end!

~ Now that one side of the pipe has been flared, the exhaust tube bracket needs to be slid onto the pipe. It is easier to do this now, then to risk bending it over the flare later.

~ With the exhaust tube support bracket on the pipe, prepare the other end to be welded onto the front end assembly. It needs to be slightly expanded so that it will be big enough to just barely overlap 2 mm of the existing tube from the front end assembly. This step needs to be taken slow, working the metal a little at a time for a perfect fit, You will notice that the pipe will also need to be slightly bend out of shape to match the shape of the front end assembly.

[Dang911]

3.

~ Bolt down the exhaust tube mounting bracket to the base.

~ Prepare all surfaces which are to be welded (degrease, remove galvanization {vinegar} and paint). Roughen the mated metal surface with a file to remove any rust or oxidization immediately prior to welding.

~ After checking that the pipe is aligned parallel to the centerline of the wood board, make one tack weld to the exhaust tube pipe to the front end assembly at 12 0-clock. NOTE: The metal is VERY thin, I welded mine with a MIG at 1 AMP. Yea, that's right one (1) Ampere. Recheck the alignment, and when satisfied make another tack weld at 3 and 9.

~ Now unbolt the entire assembly from the wood base. Once it is off the wood base, you can bead weld the rest. Make sure there are no gaps or holes in the weld. It is always a good idea to grind down the weld, (exposing gaps, bubbles and holes) and reweld where necessary.

~ Remount the entire pulse jet assembly.

[Dang911]

4.

~ The last step is positioning the air/fuel tube. Slide the Tube though the alignment rings located on the support bracket. Distance the end of the air tube (steel) 3/8" from the front of the small intake flare.

~ Looking down on the air tube, make sure it is horizontally centered.

~ Tack weld the air tube where it runs though the alignment rings.

~ Using the special tool provided, make sure the fuel tube (runs into the small intake) is centers horizontally. The tube should be bent down slightly just so it follows the downward slop of the intake.

~ Set the gap of the sparkplug to 3/32" and screw it in, Be careful not to cross thread or over tighten it!

[Dang911]

So there you have it. Took me a total of about 3-4 hours to complete. Now we can discuss it, and I will later make my suggestions for what I liked and didn't.

I am going to start a new thread for its running and fuel system (I got a little fancy).

[larry cottrill]

Well, Dang, I finally thought of a few questions.

How easy was it to get the starting air tube aligned with the intake? How did you hold it for welding? Do you have a photo of how it was supported to keep it aligned?

What do you think of the simple wire support for the tail end? It looks like you got really good side-to-side alignment of the tailpipe, but I can't really tell whether the up-and-down alignment is good or not.

Of course, I want to know your feelings about the finished product as well as the building process. I'm certainly glad you mustered the courage to accomplish the welding yourself! How difficult would you rate the welding? Could a beginning high school weldor actually do it? To whom would you recommend such a kit? What if all the material was, say, twice as thick as what you were working with - would that make a big difference to a beginning weldor? Would it have been significanly better and/or easier if the tailpipe had been provided?

How do you feel now about kit price? Would you still hold to your original $90 US estimate - or recommend significantly more or less? Another thing I didn't really consider is that a beginner most likely won't understand how much ancillary equipment is needed for starting and running (fuel setup, ignition and starting air) - so the real cost if you don't already have this stuff lying around is much higher than the kit price. Does that make a difference? (Of course, all that would be needed if you had bought a finished engine.)

What other questions should I be asking?

L Cottrill

[Eric]

Hey,
Nice job, just wanted to mention you should cover the board with aluminum flashing or at very least aluminum foil before running the engine. Even aluminum foil will reflect a large portion of the IR and keep the board from catching on fire as fast.

Eric

[larry cottrill]

Yes, I always put an aluminum heat shield under the engine (as recommended in the instructions ;-) though I didn't have this feature on my old Dynajet mounting board. It got pretty charred in just a few 15- or 20-second runs.

The heat shield is especially important in the case of my FWE engines, because the front end gets so hot so fast!

L Cottrill

[Dang911]

Sorry for not getting to these questions for a while, I have been really busy with school, we are on the block system, so I just had finals on Thursday and Friday. On to the questions.

The starting tube was VERY easy to align, it was basically self aligning, all I had to do is eyeball the air tube 13 mm from the start of the small intake centered it horizontally. Then just a 1 second tack weld on the rings that the air tube went through, and it was held it in place just fine!

The simple support wire at the end was almost useless, it supports the top of the exhaust tube, not the bottom. Supplying a simple L bracket that would need to be welded onto the bottom of the exhaust tube, and screwed into the wood base would be quite satisfactory, the flimsy and fussy wire bent support didn't do the job well.

The concept of the kit was excellent, and the fabrication was light, with tools everyone should have. The kit was intended that you also have a welder, but unfortunately, it looked like the kit was intended for someone with a very expensive welding setup. Since the metal was so thin, I ended up welding it with a MiG, at 1 amp, yes just one (1) amp!!! This would not be good for a beginner welder, and was difficult for me, although I would consider myself practically a beginner. (since that welding, I now have access to a miller cyncrowave 350, so my welding problems are all over hehe)

To fix the above problem, the kit should be made with thicker material, lets say 1/16". This will make it a true beginners kit. This is what I had the most trouble with, and I would want changed. With thicker metal, it will be easy to weld it with different welding processes, and lower quality welders, for people with only basic skill.

This "kit", in my opinion appeals to the noob. I myself can be the best example. I had fussed on building my first own, and still unsuccessful pulse jet. When I put this pulse jet kit together, and had it running, (its very reliable, starts instantly all the time) I now know more about pulse jets than what this forum could offer, it was that experience that really got me hook. Now in the upcoming days I am ready to fire up my all stainless 55lb lockwood, I can't wait. All of that energy coming from this kit, which helped me gain the fundamentals, and get a working, easily built pulse jet.

As we see on this forum there are many people who see these and are astonished by them, and then set out with millions of questions, only to find out that they are too difficult to build, or they do not have the resources to build it. This is there chance to get a reasonably priced kit, which can get them into pulse jet experimenting!

The price remains the same, $90-$110 would be a good price for this "guaranteed" working pulse jet engine, that is very easy for the beginner to build.

The last concern is starting up the engine. For this you are right, you need some special equipment. But nothing extraordinary. I haven't tried, but it is probably possible to start this up using a bicycle pump, what do you think? As for the spark, there are many alternatives out there, that are not only reasonably priced, but ready to work right out of the box. I myself built my own sparker unit with a 555 chip and a rectifier mosfet, but that's just me. For fuel I had great success with an "off the shelf" set up. Two of them in fact. One was a 20 PSI regulator to a big turkey fryer ($23) that hooks up to a 20lb propane tank, the other was a small torch ($13), that just had to be disassembled, and reassembled, minus 2 parts (diaphragm, and flow meter). After that I had those small tanks pushing over 80 PSI of propane, even though I only needed about 18 to run the engine, 12 once it was warmed up!

I still apologize for the delay on pictures of this engine running, please bare with me, I live in an upscale gated neighborhood. I ran this engine once, and got 5 complains from my non tolerant neighbors. When my Parents and I came back into the house and listened to our messages, I took a lot of crap.... Because of this I can only run this engine in remote places. The night pictures and video are what will be the hardest for me to get, I still haven't seen it run at night. This is all top priority on my list, and I should be able to the media by early next week.


Oh and as far as the aluminum shielding goes, I didn't have any thick aluminum sheet and didn't bother for foil. I ended up just placing some cut up road sign directly under the combustion chamber. Yes it was too late I had already chard the wood, and it actually caught fire once but, oh well its MDF......

[larry cottrill]

Dang911, thanks for your critique. My responses:

The starting tube was VERY easy to align, it was basically self aligning, all I had to do is eyeball the air tube 13 mm from the start of the small intake centered it horizontally. Then just a 1 second tack weld on the rings that the air tube went through, and it was held it in place just fine!

I knew this shoudn't be difficult - however, I'm still not understanding what you did to keep alignment on the intake centerline while you made the first tack weld. Please explain further.

The simple support wire at the end was almost useless, it supports the top of the exhaust tube, not the bottom. Supplying a simple L bracket that would need to be welded onto the bottom of the exhaust tube, and screwed into the wood base would be quite satisfactory, the flimsy and fussy wire bent support didn't do the job well.

Yes ... that was not the finest thing I've ever designed. It's funny: when I was shaping the 1/16-inch SS (type 308) wire, it seemed so hard and stiff that it should really work well. Then, once the piece was done, I could see that it was going to be pretty easy to distort out of shape. I had a feeling this was trouble, and should have held you off a few more days while I fabricated something better. But, I was already pretty late in getting you your engine, so I let it go ... shouldn't have done that. You're right, a simple sheet steel bracket and a hose clamp would have been a lot better.

The concept of the kit was excellent, and the fabrication was light, with tools everyone should have. The kit was intended that you also have a welder, but unfortunately, it looked like the kit was intended for someone with a very expensive welding setup. Since the metal was so thin, I ended up welding it with a MiG, at 1 amp, yes just one (1) amp!!! This would not be good for a beginner welder, and was difficult for me, although I would consider myself practically a beginner.

To fix the above problem, the kit should be made with thicker material, lets say 1/16". This will make it a true beginners kit. This is what I had the most trouble with, and I would want changed. With thicker metal, it will be easy to weld it with different welding processes, and lower quality welders, for people with only basic skill.

That's a good point - the same thing Eric mentioned to me, privately. Thicker steel would also make for longer life, and (probably) nobody's under any illusion that they're going to fly this engine, anyway.

Probably my number one mistake was not providing a tailpipe tube. This was based on the really stupid assumption that, since antenna mast tubing is available everywhere, it must be the SAME everywhere. Dumb assumption. It would have cost almost nothing to use a little bigger box for shipping and supply the tailpipe with the front end, thus providing a complete kit.

This "kit", in my opinion appeals to the noob. I myself can be the best example. I had fussed on building my first own, and still unsuccessful pulse jet. When I put this pulse jet kit together, and had it running, (its very reliable, starts instantly all the time) I now know more about pulse jets than what this forum could offer, it was that experience that really got me hook. Now in the upcoming days I am ready to fire up my all stainless 55lb lockwood, I can't wait. All of that energy coming from this kit, which helped me gain the fundamentals, and get a working, easily built pulse jet.

As we see on this forum there are many people who see these and are astonished by them, and then set out with millions of questions, only to find out that they are too difficult to build, or they do not have the resources to build it. This is there chance to get a reasonably priced kit, which can get them into pulse jet experimenting!

The real "red flag", though, was when you psyched yourself into thinking you just couldn't weld it. Of course, you recovered admirably after reconsidereing, but that really made me stop and think about the feasability of welded kits. Think of how many beginners could ruin their kit thinking they could weld it and not being able to. I doubt that there is any caveat I could write that could really convince someone NOT to try it if they believed they could just go ahead and hack away at it and get it. At least you knew you might be in trouble - a lot of beginners would never consider that possibility. I can figure out how to take the time to produce the kits - I CAN'T take the time to deal with dozens (hundreds?) of disappointed buyers who thought they could weld their kit and ruined it!

There are a couple of ways around this. I could offer a "shipping plus $10" kind of service for repairing botched kits. However, this sounds like a poor mode of customer service - if your offering a "kit", there is a reasonable expectation on the part of the buyer that they can build it successfully. Otherwise, what's the point of offering it as a kit? A better solution, I think, would be to offer a kit where the tailpipe and starting tube could be slipped on and clamped to make a running engine, with the OPTION of welding "at your own risk", with lots of warnings about the difficulty involved. Maybe that would be acceptable from a marketing perspective - a "no weld" kit that could be optionally welded, at the risk of the purchaser.

Of course, what you've said about thicker material would help this somewhat, but believe me - there are still a lot of people who would ruin it, even with 1/16-inch steel parts.

The price remains the same, $90-$110 would be a good price for this "guaranteed" working pulse jet engine, that is very easy for the beginner to build.

Well, that's better than I expected. But, even at that figure, I would have to be turning them out with a MAXIMUM of three hours of my own labor to feel like I'm getting ahead. If I had good equipment for cutting and forming the chamber cones and jigs for all the welding, I could probably do them in short-run "assembly line" fashion and end up with 2-3 hrs invested in each one. So, it seems doable (unless these actually appeal to thousands of people, all of whom order immediately - ha ;-).

The last concern is starting up the engine. For this you are right, you need some special equipment. But nothing extraordinary. I haven't tried, but it is probably possible to start this up using a bicycle pump, what do you think? As for the spark, there are many alternatives out there, that are not only reasonably priced, but ready to work right out of the box. I myself built my own sparker unit with a 555 chip and a rectifier mosfet, but that's just me. For fuel I had great success with an "off the shelf" set up. Two of them in fact. One was a 20 PSI regulator to a big turkey fryer ($23) that hooks up to a 20lb propane tank, the other was a small torch ($13), that just had to be disassembled, and reassembled, minus 2 parts (diaphragm, and flow meter). After that I had those small tanks pushing over 80 PSI of propane, even though I only needed about 18 to run the engine, 12 once it was warmed up!

Yes, a propane-powered FWE with the starting air tube is a snap to start, just by following the directions. Fueling is another excellent opportunity for liability problems, however. How many beginners are really qualified to set up a propane rig like you're talking about? Some 10-year-olds could do a good job; some 20-year-olds will burn down their garage, or worse. That part of it is a terrible responsibility. It might only make sense if I sold special propane rigs specifically designed for it - but that only lessens the potential problem; the liability would still be there, in terms of incompetent users.

I still apologize for the delay on pictures of this engine running, please bare with me, I live in an upscale gated neighborhood. I ran this engine once, and got 5 complains from my non tolerant neighbors. When my Parents and I came back into the house and listened to our messages, I took a lot of crap.... Because of this I can only run this engine in remote places. The night pictures and video are what will be the hardest for me to get, I still haven't seen it run at night. This is all top priority on my list, and I should be able to the media by early next week.

No, I don't suppose someone living in an exclusive community expects to be assaulted with pulsejet noise after dark! Good luck.

Oh and as far as the aluminum shielding goes, I didn't have any thick aluminum sheet and didn't bother for foil. I ended up just placing some cut up road sign directly under the combustion chamber. Yes it was too late I had already chard the wood, and it actually caught fire once ...

Well, the shielding doesn't have to be thick. What I showed in the FWE photo posted earlier is almost paper thin - cut easily in a few minutes with big scissors, from a $3 clothes dryer duct from Menards. Aluminum reflects about 97 % of the infrared that hits it, so it really doesn't need to amount to much to get the job done. Even if your board is already charred, it would be a good investment, and is very easy to do.

Thanks, Dang, for your evaluation! Feel free to add more comments any time you happen to think of some. Now, get someplace out in the country and get some photos of the Sveldt Lady in action!

L Cottrill

[larry cottrill]

The last concern is starting up the engine. For this you are right, you need some special equipment. But nothing extraordinary. I haven't tried, but it is probably possible to start this up using a bicycle pump, what do you think?

I guess I didn't really address this.

I think this is possible - after all, it isn't that hard to generate 30 PSI with a small hand pump. The problem would be that you almost need a "third hand" to do it. Of course, maybe one of the little foot-pedal tire pumps would work just as well.

The difficult thing about this is that with my normal, compressed air starting method, the air ceases to be one of the variables. That's why it's so easy to get a quick start every time. With a hand or foot pump, the air is going to come in gusts - great for the Dynajet, but not so great on an engine where you're simultaneously feeling your way along toward the right fuel level. Now, if the fuel system were "standardized" - everybody using the same regulator, same pressure setting, same hose, etc. - THAT would cease to be a variable, and the gusty air wouldn't be so important. That is, if the fuel flow is set properly as a "constant", then somewhere along the "bell curve" of the starting air gust, the mixture will be just right and the engine will catch hold and start running. I don't know if this is a very clear explanation. The point is, you get good starting by minimizing as many of the variables as you can.

So - how about this:

Make and sell a starting rig just for my class of engines. What it would be is a regulator, a standard length of standard size hose (i.e. a "calibrated leak" from the regulator to the fuel valve), a standard needle valve in series with a push-button valve and a nice "tire pump" with a piezoelectric (or other suitable type) spark unit and wires (remember - you really only need a spark for the first split second that you achieve the right mixture in the chamber!). Also a short starting air hose from the pump, of course. The pump, valve and sparker would be integrated onto a portable chassis that would sit on the ground. The push-button fuel valve would be equipped with a "keeper" that can be slid over it to hold the button down.

What the user would do to set up is: Connect the regulator to the propane tank (preferably a "tool free" operation). Set the regulator to the standard recommended pressure. Open the needle valve to the recommended setting for starting (it could have a numbered dial or some such). Press the button valve for two seconds to purge air from the line. Connect the other end of the line to the fuel tube on the engine. Connect the spark wires to the plug. Connect the starting air hose to the engine.

To start: Press the fuel button and stroke the pump. The pump, as it goes through its stroke, excites the piezoelectric sparker at the same time it is supplying air. If it doesn't fire, release the button until you try the next stroke of the pump. If it does fire, but doesn't sustain, immediately stroke the pump again. If it DOES sustain, hold the button down and slide the keeper onto the valve button to hold it on. Then, immediately remove the spark wires and the air hose. To stop the engine, slide the keeper off the valve button. To adjust power, change the needle valve setting, of course.

Such a starter could be reasonably priced, and would be a logical product offering. With a decent quality air pump, regulator, valves and hoses and a piezoelectric sparker, it would be extremely reliable and trouble-free. It would be almost a perfect accessory offering - you'd only need to buy one in your lifetime for all the engines (of this or similar size) that you'd ever want to build or buy. It would eliminate the need for the user to gather all this equipment together and build it himself - which would make me feel a whole lot better about the liability issue.

Now, what do you think?

L Cottrill