I think I need help. A lot. Really.

[Tim36]

That's great. put's my effort in the shaddow somewhat. will having the venturi on the side affect air flow? how are you doing your valves too, as they're my major concern. that and the people next door... having just moved into town wonder if they like loud noises... I've just been drilling the holes in a plate and lapping the surface, but I'm stuck for the pattern of the valve lay out. anyhow, i'll have a go at drawing up my ideas. brilliant machining you've done, i need to play with my lathe more... cheers guys

[Ape]

Finished the actual intake today. Got it just right at 40 by 40mm. Seven 5mm holes will have to suffice. Or it's back to the drawing board

Tim, I think not. Your efforts have lead to a completed jet, while all I have to show for mine is an intake.

Valves and valve retainer plate are basically the petalvalve layout, as it seems this is the way to go for small PJ's. I have been looking at the designs available for DL on this site, and gone from there.

And yes, you need to "play" with your lathe more! Lathes rule! Or well. . I love the one made available to me at work, it's just such a brilliant machine. Still aquiring skill, though(being an apprentice and all). Some of the oldtimers. . well. . the things they can do with it, it's incredible.

Cheers

[Ape]

Oh, and Tim, btw, I almost forgot. The venturi-thing. heh. I thought, because I failed to read up on the subject matter, that the venturi was the nozzle-system, through which fuel was delivered. Basically, a PJ'ish name for the carbeuretor-like system employed.

I have since rectified my mistake

So, to summarize; I'm gonna have a nozzle on each side of the engine, delivering a spray (or whatever you'd call my attempt at an aerosol) of liquid fuel mixed with whatever I find reasonably accessible and cheap, into the mouth of the venturi.

If I still got it wrong( the terms and concepts, that is) please set me straight, before I embarass myself any further(if that's at all possible)

[Mark]

Maybe it's just me or my computer, but it looks like the patina is stainless steel? On your next head you might try to squeeze in a few more holes/ports.

[Tim36]

lathes do rule.
I'm going to do the same thing with mine regarding fuel, and just run the fuel in through the side into the venturi. I'm going tu use butane, because I'm using a little gas camping stove for the fuel source. I've had trouble with the valves buckling when I clamp them down on the valve plate but I assume that was due to having too much high temp silicone on the plate. Reckon I should actually be putting anything on the valve plate? Do you have access to spring steel / reed steel? I've been using feeler gauges, but I pulled an old air con pump apart at work, and they have a nice bit of spring sheet in them...
Any how, I'll put up my ideas for the valve plate, but I'll give the petal plate another go. I think I've made about 6 plates now... including one very failed friday night attempt at a valve grid set up...

[Tim36]

wouldn't let me submit the picture in last post... hmm... anyhow, I don't really thing the spiral one would be any good.

[Tim36]

I found this re-typed summarised explanation of the pulse jet theory by Franco Marcenaro at http://users.bigpond.net.au/pulsejet-pjaa/theory.html

I'm sure I'ts already been posted somewhere else, but it's worth a read.
cheers

[Ape]

Mark: Nope, it's 6262-t6 alu, I've just been buffing it for like ten minutes at 2k rpms And yeah, there might have been room for one more hole there. . next time.

Tim: I think(hope) I have access to spring steel, but word from R&D haven't gotten through to me yet ( Not MY R&D unit, but the company I work for. One of the engineers working there likes the idea of building a PJ, and has sorta half-promised he'd try to get some proper spring steel for me). And I have been a lazy boy, so haven't checked if my usual hobby suppliers can deliver. Will do today, though ;D And on how to actually do the reeds? No clue. None. But for starters I'll just pretend I know they'll get some cooling from the liquid fuel, and have some (a very little bit) protection from the retainerplate. I think etching them would be the way, but not too sure if I have the patience (or skill, for that matter). I don't know about the silicone. You are the first one I see mentioning it, but I AM a total nabcaek, so. . nfc, sry

And yeah, the Marcenaro paper, I read that. I tried to read the schmidt-gosslau thing as well, but the version I have is so poorly scanned, Im getting a headache trying to read it



Cheers

Edit: Not blaming whoever scanned it, great that someone bothered, and might not be the scan itself, could be the original, or whatnot. Headache is very real, tho

[Mark]

I guess what I saw on the face of your valve head was that the drill bit chattered a little producing that slight chipped/faceted look you might see when drilling something hard like steel. On the Dynajet the holes/ports are drilled just undersized and then redrilled again with a straight reamer to produce a smooth appearance. I really liked the spiked look you had on your head. Notice on most petal designs that they try to get as may holes as possible, more power.
http://www.precisionedge.com/products_ream.html
http://www.cmitools.com/dril.html#REAMER
Straight reamer (precision)
"A straight reamer is used to make only a minor enlargement to a hole. The entry end of the reamer will have a slight taper, the length of which will depend on its type. This produces a self centering action as it enters the raw hole."
http://en.wikipedia.org/wiki/Reamer

I was reading up on 6262 aluminum and came across this fly reel when I asked for images of 6262 on Google. ha
http://www.eveninghatch.com/images/Prod ... Silver.jpg
"20% lighter than legendary original Battenkill reels."
"Machined from bar stock 6262-T6 aircraft-grade aluminum for durability and low weight
Anodized black or titanium finishes are more durable than the painted finish on die-cast reels"
http://www.eveninghatch.com/Products/orvis_reels.htm
Another "almost there" design.
St. Croix Legend Fly Reel
Made from “Aerospace Grade” 6262-T6 bar stock aluminum.
Item #Legend Fly Reel
http://www.russellsbats.com/sitebuilder ... Fly%20Reel
http://www.russellsbats.com/catalog/c27_p1.html

"Here are some BigFoot Valves for Dynajet Bailey Afm600 OS And Jetbill Engines. They have been cut using a cnc waterjet machine which mean the valves have no mechanical or heat stress on them. They have been made from 6thou Blue tempered steel .
These valves are good for the engines which have become harder to seal over time as the they cover the ports better, they are also used in the fastjet engines which have bigger ports.
I have run these valves in my OS, Dyna and Bailey sportjet engines with great success I also use these in my fastjet engines."
http://cgi.ebay.com/5-Dyna-Jet-Valves-B ... 0298111401

[Viv]

And yeah, the Marcenaro paper, I read that. I tried to read the schmidt-gosslau thing as well, but the version I have is so poorly scanned, Im getting a headache trying to read it

Edit: Not blaming whoever scanned it, great that someone bothered, and might not be the scan itself, could be the original, or whatnot. Headache is very real, tho

Are these the papers you want? not sure but the scan is good, i think it may have been done by Mark originally?

Viv

[Mark]

I think it might have been Mike that posted the Schmidt stuff? It was a good read.

[Ape]

Viv ; yes, those are the ones, same scan. I have been getting through a few pages, and I realized I should just do shorter stints, thanks for trying, tho ;D

Mark; yeah, yeah, I know reamers, no worries, and its not, Im ashamed to admit, because I don't know how to do it proper, it's that I was pressed for time, and got lazy and careless ;( I'm afraid the reason you think the countersinks looks like they're done in SS is. . *shame* I did them by hand with a dull countersink. I know, I know, but it was within reach.

On a lighter note; Yeah, thats the alu we use. We used to have 6061 alu, but it didnt respond too well to the kind of surface treatment we needed, so
we ended up with 6262-t6. It's kinda nice (read: really easy) to work with.

And thanks, I have seen those different valvelayouts as well, and also realized I could have a circle of say 2.5 or 3mm holes inside the 5mm ones. Back to work

Thanks for all the input, guys.

Oh, almost forgot. Currently eating my "got it just right" words. . .they're not that tasty ;P

Edit: I like those fly-reels. And I think I see why you linked to them, too. Cheers
Re-edit : Nope, those were not the same scan. Sorry. Failed. These are good, really. Sorry ;/

[Tim36]

I did think the silicone sounded silly... but it was in the plans I was looking at. I've been looking at these photo's kicking myself for not taking my time. I think I will start over. As soon as I get the current jet to work. just once... Being an automotive mechanic, I don't really have access to any fancy cutting machinery, how would I go about cutting the spring steel into the valve shapes? I've just been using feeler gauge strips, which is a pain, because it means all the valves are individual, and I have to allign them all.

ALso, please in stimple mechanic tongue, what sort of aluminium Should be used for machining the intake? I'm assuming it's a hagher carbon sort of thing?

[Tim36]

Ha ha, finally got mine to run properly. Turns out the tail pipe was too short. I ended up using the carbie off a drag bike jetted for methanol to fuel it, and i just kept practicing with the valve cutting. Yay! job done

[Viv]

Hey congratulations

Do some pictures when you get time or a vid

Viv