Another (Crazy?) Idea for Engine Kits

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re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Fri Dec 16, 2005 4:52 am

Dang -

Your kit was in the mail today, though not until about 3:15 PM. So, maybe Saturday, maybe Monday. I'll send an email tomorrow with the USPS tracking number so you can check it out on usps.com.

For the tailpipe, you go to the Electrical section, then to the tiny subsection devoted to TV antenna stuff - twin lead, chimney brackets, etc. The tubing you're looking for will be 1.25 inch OD painted steel - I've seen it painted ugly beige, gold and bronze colors. I think it's less than $1 per ft length. BOTH ends are unusable - one has a deep trough pinched in it, the other has a lug spot welded to the inside. The steel is less than 1 mm thick. THEORETICALLY, you'll need to cut a piece 16.5 inches in length. You'll need to slightly flare the front end to 'socket' onto the front end in your kit. Since I couldn't get the rear opening perfectly round, you'll have to hammer or stretch it it out of round a little to fit right. Just mount everything (including heat shield) on the plank and tack weld around it in several places, take it off the plank for a couple more tack welds and then finish weld between tack welds.

Again THEORETICALLY, the engine length from the front edge weld of the chamber cone to the rear end of the tailpipe should be right at 24.0 inches when you're done.

L Cottrill
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Last-Minute Suggestions

Postby larry cottrill » Fri Dec 16, 2005 6:40 pm

Dang -

As I said earlier, start up a new thread in the Valveless Forum when you get your kit. What I would like you to do is NOT address your posts to me, but just do it as a report to the forum - basically, I'd like you to pretend that you got this by answering a magazine ad by sending $50.00 to some outfit you never heard of! I want you to report exactly how it goes for you - what works, what doesn't, what's bad, what's good. The only time I want you to address me directly is if there's just something definitely wrong with it - i.e. my instructions weren't clear or were just wrong, something just doesn't fit, my dimensions don't add up, something I've told you to do is physically impossible, etc. Don't contact me privately about anything except to send photos - document the whole project on the Valveless Forum so everyone can comment and everyone can see how it goes. I would say just post selected photos that you think make the basic steps clear. Reduce the photos you post to 500x500 pixel images, maximum.

What I want you to be thinking about, and ultimately commenting on, is: What would a beginner think of this? What would an experienced hobbyist think of it? Is it too difficult for a beginning metalworker? Too simple to interest a serious jet hobbyist? What price point would make it look like cheap junk? What price point would be perceived as a total rip-off? And of course, others can chime in with their opinions, too, as they see your comments and observations as you go. I will keep my nose out of it, except as a sort of "corporate help desk" to address any real problems, as mentioned above. I MUST NOT be perceived as trying to influence your opinion of it, or to make it successful by directly working with you. That's why I don't want any private communication, other than you simply sending me your jpegs as you go through it.

Photo suggestions: Take way more pictures than you think are needed, and post only the "best" ones, but send me all of them. In most cases, get at least one hand in each "construction" photo - you're not showing objects, you're showing a human being doing something! Hands are extremely expressive, second only to the human face. Most steps should be pictured in a detailed series. For example, mounting the starting air tube in place should be shown as: (1) Sliding the tube through the rear mounting ring; (2) Sliding the tube through the front ring; (3) Aligning the fuel pipe within the intake as the tube continues forward; (4) Sliding it all the way forward so the nozzle of the air tube is 1/2 inch aft of the intake flare; (5) Supporting or wiring the tube so the nozzle is centered in and properly spaced from the flare opening; (6) Closeup of the intake flare area showing the air tube nozzle held in position; (7) Making the first tack weld between the air tube and mounting ring; (8) Closeup of the mounting rings and finished welds; and (9) Wider closeup of the entire finished front end assembly. That sounds like an awful lot, but that's the kind of detail thinking you need to do. Of course, you could refine it even more if you can think of a good reason - just ask yourself, "What would a beginner need to see to be able to get this done correctly?" Forgive me if I'm telling you stuff you already know - it's just that we're only going to get to do this once, and after it's welded up you can't go back for the great shot you didn't think of earlier.

I'm sure you'll do a great job of this! I'll have a couple more instructions on the actual construction for you, shortly.

L Cottrill
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re: Another (Crazy?) Idea for Engine Kits

Postby Mike Everman » Fri Dec 16, 2005 7:19 pm

Larry,
$50? How can you consider any business venture with as much labor as you've got socked into this as viable? No disrespect intended of course, but you're not showing much value to your time! The worst time you will ever have in life will be getting a bunch of orders for this. You might as well put a check for more than a hundred bucks with every one, IMHO. I can't see how this could ever be good for you.
Granted, I may have missed in this long thread where market price vs. cost of goods sold makes it worth all this effort... Don't forget endless support hours for noobs.

Very skeptical here, and wish so much you were expending the energy on experimentation instead!
Mike
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re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Fri Dec 16, 2005 11:53 pm

Mike -

Not to worry. The $50 was just thrown out there as an example, to try to get Dang to put a value of some kind on it while he's evaluating. One of the things I want to do is get him (and others, if they have opinions) to put a value on the kit AFTER he has it built and running. Price it too low, it looks like junk from square one. Too high, it seems like a rip-off ("Hey, it's only plain steel, blah blah blah ...").

The other thing is, I would NEVER try to put these into production with my hand blacksmithing methods. It just wouldn't make sense, in terms of any retail price people would actually be willing to pay. No, some good Production Engineering would have to be done, to trim the cost of production right to the bone.

Of course, another thing that affects price is the perceived chance of having something worthwhile when you're done. If Dang has a tough time getting it running, for example, it's just another weird project. If it starts right up the first time and runs great, I should be able to get a great endorsement to use for advertising. Believe it or not, if done right, that can make a HUGE marketing difference in terms of perceived value. In fact, a "guy next door" endorsement is often more effective than some "expert" testimony. Remember, what I want is something a real beginner can puddle together and get running with minimum fuss. Dang's not quite a beginner, in terms of metal skills, apparently, but let's wait and see what his perceptions are while he builds it and when he tries to get it running.

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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Sat Dec 17, 2005 12:53 am

I know metal, but I'm no machinists. I don't have a lathe, mill, break...etc. I only do machining when I'm at shops, otherwise I have to creatively get around it.

I am currently in the process of learning the art of CNC. My school has a CNC router and Lathe. Sitting for 3 years, never used, I know more than anyone, but still I know VERY LITTLE.

I don't even have a welder..... I do work for a welding parts company though, as a designer/engineer. I can just use one of the test machines. I have designed multiple parts for welding guns. Mostly the connectors of the gun to the line, and the line to the machine. You can see MY designed parts on Lincoln, Miller, Tweeco, Thermal Arc, and more.
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Final Welding Instructions

Postby larry cottrill » Sun Dec 18, 2005 3:15 am

Dang -

Man, how does a young guy like you get a job like that? Sounds like a good, challenging design job.

As I promised, here are more detailed instructions on what you need to do to get your kit built:

Tailpipe Welding Instructions

Make your mounting plank and heat shield as shown on the drawings. Mount the front end assembly on the plank using four short bolts and tee nuts, with the heat shield sandwiched in between. Make sure that the two small holes at the rear end of the shield line up with the small nail holes in the plank!

Cut your tailpipe from the antenna mast material. The easiest way I have found for accurate 'square' cutting of tubing is to wrap the straight edge of a piece of heavy paper clear around, then trace it with a fine-point permanent marker. SLIGHTLY flare one end of the tailpipe tube, so it will just fit over the rear of the front end assembly. Tweak it a little out-of-round to fit over the two weld bulges visible in the rear-end photo posted earlier. It should have just enough flare to center itself on the assembly, maybe a mm or two! A close fit is important - take your time to get it right!

Now, slight the SS wire strut onto the other, un-flared end of the tube. This should be a slightly snug fit, and it should go on easily. Slide it on a couple of inches without distorting it.

Place the flared front end of the tailpipe against the mounted front end assembly so it fits together properly, and gently position the two legs of the wires strut against the metal heat shield so the rear of the tailpipe is supported. Temporarily tape the pipe to the front end assembly with a 4-inch length of masking tape.

Gently slide the SS wire strut back or forward to line up its two loops with the screw holes. With a small screwdriver, run in a no. 6 panhead sheet metal screw, with a no. 6 flat washer, into each of the two holes. Run each screw down tight to hold the wire loop, but do not overtighten.

Set up the plank and mounted parts on a level surface for tack welding. If your mounting plank is wider than the heat shield, protect the exposed surface from weld splatter with scraps of sheet metal, aluminum foil, or other non-flammable material. Use a heavy object, such as a brick, as a stop against the front edge of the plank. Use a similar object as a stop against the rear end of the tailpipe, pinning it against the front end assembly. Once these are in place, remove the tape and make sure everything stays securely in place. Proper orientation of the pipe against the rear of the front end assembly is the critical point.

This is the point at which you can form a shield of several layers of aluminum foil around the intake flare to protect it, if desired.

Make a small tack weld at the very top of the joint. You should use very little filler rod, instead trying more to blend the flare down into the rear edge of the front end assembly. Duplicate this with a small tack weld at the leftmost point, and again at the rightmost point. These should be fairly small but solid, well-formed tack welds.

Once you're sure this is properly done, remove the front and rear stop blocks and remove the two small screws from the SS wire rear strut. Then, remove the four main mounting bolts, and carefully remove the engine from the mounting plank. Set the mounting plank and heat shield aside, out of the immediate work area. Turn the engine over on its back and make a fourth tack weld, right at the bottom of the flare.

Imagine the four zones of the joint, between the tack welds, as compass directions NE, SE, SW and NW, as seen from the rear. Starting at the bottom center tack weld, weld the SW segment by melting the flare into the adjoining metal of the front end assembly, using as little filler rod as possible. This should be smooth, continuous welding until you have blended it into the side tack weld. Now, turn the engine over (180 degree rotation) and weld the NE segment in the same way, from the top tack weld through the side tack weld. Now, turn the engine over so the SE segment is visible, and work from the bottom up to the side, blending it into the NE weld just completed. Finally, rotate again and finsh the NW segment. Working the welds in this diametrically opposed manner will preserve the initial alignment almost perfectly. You should end up with the appearance of one continuous weld clear around the joint, without holes or gaps of any size.

Remove the intake shield, if used. You can use a small flat or half-round file to clean up any sharp points or other superficial problems on this weld. That's all there is to the tailpipe weld.

Starting Air / Fuel Tube Welding Instructions

Again mount the engine and heat shield on the mounting plank. Run in the four main mounting bolts first, then the two small screws at the rear strut.

Slide the long straight end of the starting air tube through the mounting rings from the rear to the front. Rotate the tube up (clockwise as seen from the rear) so the fuel pipe enters the intake flare as you continue to move it forward. Note that the long, free end of the fuel pipe is rotated up away from the area of the mounting rings - this is to protect it during welding. Stop the forward motion when the nozzle end of the air tube is 1/2 to 5/8 inch from the intake flare. This is the correct position, longitudinally (front-to-rear). Raise and lower the nozzle end of the air tube until it you can see where it is exactly centered between the two sides of the intake flare. It should appear closer to the bottom than the top of the intake opening at this position. This is the position you MUST have it in when you weld.

Use a small C-clamp gently clamped onto the tailpipe as a rest to establish this exact position. Take your time in working this out! Remember, what you want is the air tube precisely centered from side-to-side in the intake, and 1/2 to 5/8 inch aft of the flare edge. Once you've established the right place for the C-clamp to be, tighten it slightly on the pipe. You can rely on gravity and friction to keep the pipe resting properly against the clamp, but I'd suggest wrapping with fine wire to hold it in place (your welding will be about three inches away from the intake area, so thin copper or aluminum wire should be OK to use).

There are actually four weld points to hold the air tube, and they are easy to reach. Your main difficulty will be that the air tube is VERY thin steel - only about half the thickness of the mounting rings it fits through. So, at each weld point, you must concentrate your heat on the mounting ring, add a little filler rod, and "pull" the weld down onto the tube and quickly blend it in. (It sounds more difficult than it is.) The four weld points should be obvious: Each mount ring has a lug bent down over the tube as it goes through; the end of this lug is one weld point, and the top of the hole where the lug is bent forward is the other. (This will be MUCH clearer when you see it in real life - trust me!) The welds need not be extensive - something like large tack welds is all we're after.

Re-check the perfect side-to-side alignment and longitudinal spacing of the air nozzle at the intake. Once you're sure it's right, go ahead and make your first weld at the rearmost weld point. Work your way forward, doing each little weld in turn. When done, remove your wire wrapping and C-clamp from the air tube and tailpipe, respectively.

At this point, the long straight section of the air tube lies a little close to the front edge of the combustion chamber. You may gently bend it out a little, if desired. Now is also the time to gently bring the long, free end of the fuel pipe down parallel to the long part of the air tube. You can put a gentle outward bend in the last couple of inches of it, also, to keep your fuel hose away from the hot chamber wall.

All that's left is to align the fuel pipe inside the intake. What you do is use a small flashlight, and sight down the intake from every position you can get your eye in, and judge where the VERY END of the pipe is, in relation to the upper (curved) wall and bottom (flat) wall of the intake. Like the starting air nozzle, it should be exactly centered laterally and a little lower than center vertically in the intake cross-section. GENTLY use the grooved end of the special tool to leverage it one way or another to get it properly centered. It is VERY important that the end of the pipe be well-centered in the area of the intake, for good starting and wide throttleable range, so be ready to take your time and exercise patience with this step!!!

That's it. You should now have an engine that will start and run. The only additional step would be to provide a tail-end flare - but I would hold off on that until we're sure that the length is just right.

L Cottrill
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Sun Dec 18, 2005 4:44 am

Thanks for those detailed instructions, they clarified everything, as of now.

I got that job because my neighbor owns the company. I would always talk about how I was very good at designing parts in CAD, mainly 3D, he brushed it off.... Some weeks later he had a part he could not figure/draw. That was my test, make the part, I have a job. I made the part, and got the job, and created one hell of a portfolio for college, come on patented parts at my age??~!!!

One question about fuel. Do you think I can get away with the small Benzomatic propane bottles and a large regulator, or should I use a large 5-10 lb propane tank.......

I would like to use the small tank, because when mounted, it would make for a nice presentation.
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re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Mon Dec 19, 2005 1:34 am

I think a small propane bottle would work well for a few minutes, without regulation - you would just have to nudge the valve open a bit more every 30 sec or so to maintain flow as the cylinder cools. That would be a very simple setup, if you make the 'torch head' valve fitting properly. Don't try to save pennies on this - use the best torch head you can afford. You'll have to carefully drill out the sintered bronze strainer/restrictor which can be seen from the bottom. It's easy to do, just working gradually with a slightly undersize twist drill.

However, I personally prefer a larger tank with a regulator, so the pressure on your control valve (needle valve at the output side of the regulator) is constant, so the valve is simply adjusted to the desired flow. "Set it and forget it." That's a quite a bit higher-priced system, though, since you need a regulator that delivers a LOT of gas flow - way more than a torch or even a big grille would need. You don't need a lot of supply pressure; I usually use about a 10 or 12 PSIG setting.

Either way, be sure you have at least 4-5 ft of rubber hose between the supply and the engine fuel pipe.

I hope you'll have your package in hand tomorrow. USPS tracking hasn't shown a thing useful, so far - but, I've seen that happen before, and people still got their stuff.

L Cottrill
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Mon Dec 19, 2005 2:45 am

Its the Holiday season, so things will be a little slow.....

Ok I already have the torch head setup, anyhow I am looking to invest in the large tank setup.

The only LARGE propane regulator I have is off of a turkey fryer, will that be enough, it should put out a decent amount of gas, cause those large burners surely do use it. Since I still would like to use the fryer, I was looking at this one http://www.turkey-fryers.com/5HPR-1_hos ... ulator.htm

It doesn't have a pressure gauge, but says its good up to 20 PSI..... I could always add a pressure gauge after the valve. Just tell me what you think......

Also what about a flashback arrestor, I know there is a long hose with ONLY propane in it, does anyone use one of these?
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Re: re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Mon Dec 19, 2005 4:27 am

Dang911 wrote:The only LARGE propane regulator I have is off of a turkey fryer, will that be enough, it should put out a decent amount of gas, cause those large burners surely do use it. Since I still would like to use the fryer, I was looking at this one http://www.turkey-fryers.com/5HPR-1_hos ... ulator.htm

It doesn't have a pressure gauge, but says its good up to 20 PSI..... I could always add a pressure gauge after the valve. Just tell me what you think......

All I can say is, try it and see if it delivers enough. If you can get your engine to run, but can't push enough fuel to force it to "rich extinction" at the high end, then something in the setup is too restrictive.

Also what about a flashback arrestor, I know there is a long hose with ONLY propane in it, does anyone use one of these?

I can't see any reason why this would be needed. It would add a lot of restriction to the flow. The only reason these are critical in welding outfits is because there is MIXED fuel and oxygen in the torch head, which means a burning MIXTURE can be forced back up into the hoses if the torch gets plugged. You won't have anything like that situation here.

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Spark Plug Prep and Starting Instructions

Postby larry cottrill » Mon Dec 19, 2005 5:58 pm

A couple more things:

Spark Plug Setting

Before tightening the spark plug into place, the gap needs to be radically opened up. Using "needle nose" pliers, grasp the outer electrode from one side near the base and gently bend if upward to an approximate 45-degree angle. If you have really bad luck and happen to break it off, the plug will still work, by firing from the center electrode to the shell. What we want for pulsejet starting is a long, thin spark rather than a short, hot one.

Try to use a six-point box end wrench or six-point deep socket of the proper (metric) size to install and tighten the spark plug, to avoid slipping off and breaking the porcelain body.

Engine Starting Instructions

Make sure the finished engine is securely mounted to the plank and that the mounting plank is solidly clamped to some reasonably heavy object. Make sure the spark plug is tightened into the plug mount enough so that the washer is compressed. Attach your fuel delivery hose to the copper fuel pipe via a short length of small rubber hose (e.g. 2 or 3 mm ID automotive vacuum hose). Make sure the fuel control valve is closed. If using a regulator, open the cylinder valve and run up pressure at the regulator to 12-15 PSIG. Open the control valve for a second or two to purge air from the fuel delivery hose and fuel pipe.

Connect your battery and high voltage leads to your spark unit. Connect the ground lead to the engine at one of the mounting lugs. Connect the high voltage lead to the top of the spark plug. Briefly energize your spark unit - the engine may bang due to a small amount of fuel vapor left over from purging the fuel line.

Your compressed air hose should be fitted out with a small hand nozzle of the type used for blowing out lines, etc. The style with a conical rubber tip is ideal. You will need to arrange things so you can have one hand on the nozzle trigger at the engine and your other hand on the fuel control valve. You must have control of both valves simultaneously. Set your compressed air regulator for 30 PSIG in the hose.

Now, you're ready for starting, so put on your hearing protection! First, start your spark unit and let it run. Next, press the nose of the air nozzle into the open end of the starting air tube and then depress the air valve trigger and hold it open. Then, gradually open the fuel control valve until the engine fires. If you get to a setting where the engine fires with loud 'sputtering', just open the fuel valve further, till it smooths out as a continuous roar. Once you have a full roar, open the fuel just a little further, and try releasing the air trigger. You should have a running engine! If so, you can remove the air nozzle from the starting tube, kill the spark and remove the HV lead from the plug before it can be damaged by the heat.

If you don't get sustaining operation, kill the fuel flow and repeat the procedure with a little less air pressure. If less won't work, try more. Once the right air pressure is found, you can use that to start your engine in seconds, any time you want.

Of course, if you just can't get sustaining operation no matter what you do, we'll have to assume the length of the tailpipe is just a little off from the ideal value, and we can talk then about how to proceed.

L Cottrill
Last edited by larry cottrill on Tue Dec 20, 2005 3:00 am, edited 1 time in total.
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Mon Dec 19, 2005 6:52 pm

Received the goods looks great, I'm in a rush off to lowes for the exhaust pipe. More later

Thanks again
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CORRECTION - Mounting Plank & Heat Shield Drawing

Postby larry cottrill » Mon Dec 19, 2005 6:54 pm

Rats! My Metric value was wrong for the 0.75 inch dimensions for the mounting holes for the tail strut. Should be 19mm, as shown below, NOT 24 mm!

L Cottrill
Attachments
FWE_III_kit_mounting_details_rev01.gif
Mounting Plank and Heat Shield dimension drawings (corrected Metric equivalent at 0.75 inch dims). Drawing Copyright 2005 Larry Cottrill
FWE_III_kit_mounting_details_rev01.gif (11.21 KiB) Viewed 5616 times
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re: Another (Crazy?) Idea for Engine Kits

Postby larry cottrill » Tue Dec 20, 2005 5:58 pm

Dang -

OK, just one more thing I thought of, and maybe you'd thought of it already: Please try to keep a simple record of your construction time (include setup time, if applicable) for each step in the process. This doesn't need to be highly accurate, just to the nearest 10 minutes or something. Try to estimate any time just devoted to photography (which may be significant!) OUT of the construction time for the step.

(Just one more little thing for you to remember to do ... ;-)

L Cottrill
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re: Another (Crazy?) Idea for Engine Kits

Postby Dang911 » Tue Dec 20, 2005 6:26 pm

Hehe, I already thought of it...

And....

I'm like 90% finished. All I need is to get to work (possibly today) to weld it up, and its firing time!!!

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 it in as far as it will let me go before the bend in the tube stops, hitting the engine?
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