Hagen's Big PJ

[Eric]

Awesome, cant wait for the full power run.

Haha... well hunters have sure decreased in my neck of the woods :) I have no need for drunk assholes sitting near our property line shooting towards us anyway.

My one friend was in a tree stand 3.5 miles away some deer came near him and then he heard BOOOOM BWAAAAAAAAAAAAAAAAAAAAAAAAA! and the deer all shot their heads up and were looking in my direction :D

I was quite impressed since i had the engine pointed in the oposite direction and it was only a 8.5 lb advanced chinese :)

That engine you got there should give you a new meaning to the word loud. Dont stand close to it for very long, you will hear through your body instead of your ears.

Eric

[hagent]

I noticed that the lower frequencies are a bit more tollerant, but I don't know if the extra power would totally offset any benifit. At the PJ meet I actually felt pain spikes inside my body from some of the smaller PJ's running around 200 hz. I just hope that the BIG one does not interfere with a persons heart rate due to the pressure pules at around 77 hz.

Eric, I saw your recent tp180-70 video. Looks real nice. I like your PJ stand. Did you use solid metal bars? What size were they? What type of metal?

Thanks,

[Eric]

The big ones make breathing interesting, since air enteres and leaves your lungs without you trying.

The stand is 5/16 and 3/8" stainless round stock

[hagent]

Sorry guys,

I was in London for a week and a half, then Singapore for another week and now I'm stuck in Melbourne for two or three weeks.

So I haven't been able to fire up the big one, and of course make all those modifications to the stand.

At least I have something to look forward to.

Cheers,

[Irvine.J]

Fly to Brisbane since your in Australia come see me and rosco! :D I'll put you up for the night if you don't mind the spiders hehehe, we can go wild in my garage. If your keen let me know. Emails at the bottom here, as is my skype.

[hagent]

Fly to Brisbane since your in Australia come see me and rosco! :D I'll put you up for the night if you don't mind the spiders hehehe, we can go wild in my garage. If your keen let me know. Emails at the bottom here, as is my skype.

Thanks for the invite James!

I really wish I could go. My wife would just kill me. I've been gone about for the last 4 weeks out of 5, and my father lives in Wollongon and wants me to try and fly to Sydney for a visit also before I head back to the states.

Cheers mate.

Hagen

[hagent]

http://www.youtube.com/watch?v=S6QQnuhl8Ak

I was able to run my pulse jet today!

I can't believe that it has taken me this long to find the time to spark it up.

We ran it a few times at the Camerillo airport. Got it nice and red hot. Here is a quick movie that shows it starting and possibly flaming out. I'm still not sure if I could give it too much propane with my current setup.

Eric when can I buy one of your cool injectors?????

I need one bad.

I wish you could have seen my asistants shirt when he stepped behind the exhaust, it was blowing like crazy. You'll notice in the video that he can't keep the camera straight, and you can hear a little echo in the back ground.

If you have ever wondered what it must feel like to be beamed somewhere in Star Trek then you have to start this pulse jet. You feel like your whole being has just been displaced in somesort of pulsating field of pure energy. Hm... well that almost does describe what really happens.

It was alot of fun, I didn't have a lot of propane plus the bags of cement were starting to burn.

Well I hope Mike will have another pulse jet fair soon. I would love to bring this along.

I still don't have any thrust measurements, I was a little uneasy about putting this monster on wheels.

I modified the mounting rail and it seemed to do a great job. I'll have to get some pictures on the mods.

I had a weld seem a the end of the exhaust crack on me, about 3 inches worth. I guess it got much hotter there than before. Gas welding SS304 is hard. If I do much more ss I will have to buy a different welding setup.

Well enough for now.

Hagen

[adam]

hey that engine is really big i got one of erics tp 180 70 pulse jet but thhat one you have there is noticely alot bigger. how much thrust does it produce and how long can you idle for on a 20lb tank and also how long will it run on full power with a 20lb propane tank, just a guestamation or somthin. thats weird that you got a crack on the exhaust you would think at the tip of the exhaust it would be alot cooler than the combustion chamber or the u bend, hmm that sucks because i am rebuiling my engine to be thicker only on the hot sections because a little while ago i got a crack on my combustion chamber and i was going to thicken the combustion chamber but i wasnt even thinking that i would have to replace the exhaust rear end.

[adam]

het hagent, i noticed in your picture that you have a electrical unit for the spark plug, well i have just a smaller model pulse jet than yours and i can start it with a naked flame at the intake and blowing it in thruog the intake pipe with the leaf blower and it starts instantly with out any huge bangs or pops, its just a steady rumble and than poof, and now the engine is running, you should try it on yours if you havent allready. its so much better and easier and its also alot fewer equipment.

[hagent]

Hey Adam,

The combustion chamber is 8 inches OD. So it's a little bit bigger than Eric's.

I'm not sure if I would want to try the flaming intake method. I have to use quite a bit of propane to just get it to start. I started it the first time on vapor only with the tank about 1/3 full. It ran for about 15 seconds before the tank cooled down enough and it stopped. I then had to run liquid to get it to start again. I didn't have a hot water tank handy to keep the vapor pressure up.

I pretty much emptied the 1/3 tank in about 2 minutes of running at near full throttle. I think I could get much more power if Eric would sell me one of his injectors (hint hint). I will have to make a better one for myself and try this again.

I gas welded the ss304 which is hard to do and has it's own problems. If you put too much of a bead it will crack. It was very difficult to hand roll (no tool) 18 guage material. There were alot of stresses still in the metal and when welding those stress put enourmous forces on the welds. I was hoping that when it got real hot that the metal would relax, but I had a few cracks here and there and I will fix them before the next run. I really want to make a go kart for this PJ, but it seems a bit harder to mount just one PJ. Most people use two smaller ones. I'll have to come up with something. I might have to do oxygen injection just for starting. But if I had Eric's injector I wouldn't need air since it starts without it by entraining the intake air.

It's amazing how different the larger PJ's feel because of the low Hz rate. It's not so ear splitting as a smaller PJ, more of a body shaking, brain numbing, eye ball spazing effect. You litterly can't see right because your eyes are shaking in your head. lol

I just found a liquid propane tank on ebay. Might have to buy one.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... &rd=1&rd=1

Hagen

[adam]

yea your right about the smaller jet they are so loud right next to it you cant even stand it but the big 70lber i have i can sit next to it with no problem because of its lower frequency but there is a difference with a big and small pulse jet, the big p jets sound doesnt fade away when you walk really far away from it, the sound is almost the same or at least can be heard from far away, i think its because it has more of a bass to it just like in someones car when the bass is full blast you can hear it shake the walls in your house from all the way down the block. well when your out there some time try and do the naked flame method trust meeee its way easy, the way i do it is i just crack it open just a little bit so that way when i light it there isnt a huge fire ball in my face, and as soon as i get a little flame, i blow it right back in through the intake tube with the leaf blower until i get the rumbling sound and you dont need much gas at all as it will rumble as you are blowing in the air, as you blow the air in its just going to sit there and rumble until you feed it some gas. once you give it more fuel and are holding the leaf blower up to it, it will start right up, and no big pops or nothin, just try not to singe off all your hand hairs as i do because i always use a short little bic lighter instead of the longer ones. so what was the thrust by the way on your engine? i think that thing will be really fast on a gokart be carefull. my gokart has pretty good excelleration and goes pretty fast and is only putting out somewhere from 70 - 85lbs of thrust occording to the plans and also with the advanced injector eric built for it.

[adam]

i guess im just really bored, well i forgot to share something with you, you said something about your tank freezing and not getting pressure after a while or something like that, well try this as i did and it works awsome with my engine al least >> get 2 smaller tanks, like 2 10lb propane tanks and have both hoses from those two fit to a t-fitting and with one hose going to the engine, now you can start with one crack open to start and to leave on idle and leave it that way and then use the other tank and throttle it up and instanly turn that valve all the way off and in a splitt second the engine will be back at idle because of the first tank that is still cracked open, and by the way, both of the tanks are right side up and not feeding liquid, i guess the pressue from the two tanks is greater than just haveing one tank were you would normally have to flip it upside down to feed it liquid so the engine can throttle up. the pressure from 2 seperate tanks should be enough to throttle your engine up and being that the propane tanks are right side up and not feeding liquid, the tanks seem to hold there pressure longer as the tanks dont freeze as fast when feeding vapor, and since your p jet is bigger than mine i guess you can crack the first tank that i normally use for starting and leaving at idle so that way your engine can get more fuel.

[hagent]

This engine should put out between 100 and 150 lbs.

I've went ahead and bought one of these! This should help solve my fuel issues and having to put the tank upside down.

http://cgi.ebay.com/ws/eBayISAPI.dll?Vi ... d=1&rd=1

[adam]

hell yea, someguy just recently told me to try a forklift propane tank but i aint really looked in to it, he said that it has a valve for letting out liquid and one for gas,, i read the little ebay auction you posted and i didnt know it can work with the propane upside down or side ways or any other diffe3rent angles, i guess i gots ta get me one now.

[Eric]

Hey Hagen
Sorry I havent been intentionally ignoring you

I still havent gotten around to repairing my lathe to the point where I can do precision work, so an infinijector with extremely high entrainment is not going to be rolling out of my shop any time soon, but I can make a basic non entrainment version with only a tiny bit of very simple machining, they are quite effective.

Basically the liquid propane would be supplied through a 1/4" OD stainless tube, that would expand into a 1/2" or 5/8" stainless tube, and the final injection area would be of equal or greater area as the large tube, so the liquid propane will expand as much as possible, and warm up from heat absorbed by the injector, and then get injected.

Even your big engine should be able to throttle pretty high on a fresh warm tank of propane running just vapor through the 1/4" tube. It wont make it self starting, but with a fixed air tube at the best position you will be able to start it with less than a half second pulse of air almost every single time.

In the video I see the large part of the tail compressing inward durring the low pressure phase, you should put a ring of 3/8" round stock around this part to keep it from flexing harmonically like that, the flexing will cause work hardening and crack it like crazy, if that is the area where you had a crack happen, then that is the problem, not the heat.

Also flaring the big pipe will give it some resistance to flexing and also help it breath a tiny bit better.

Heating the propane before injecting it can be a big help with engines running on liquid propane. From your run video it looks like the combustion starts to get pretty rich without much increase in thrust, and the flashes of yellow show that somethings not right in there.

I'd be happy to draw up a sketch of the injector if you think you could make it yourself, I am so buisy with 8934750238745039847 other projects, the less I have to build the better.

I really want to see you get that thing running at its full potential!

eric