Odd Metal jars

Moderator: Mike Everman

Post Reply
kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Thu Jan 19, 2012 4:53 pm

I want to build a reynst combustor/pot but Iam still unsure on where to start, layout, dimensions ect ect.

I'll go back through the last few pages in this thread, ill probably understand a lot more now that I have 6 weeks experience under my belt.



I have built some adjustable augmentors for the thermo-jam. I wanted to give myself a caliber ratio as a start point. So I have gone for 13% of the exhaust length, which is huge! So the augmentors are 100mm long approx. Atleast ill have somewhere too work from. Tonight ill try them out.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Odd Metal jars

Post by PyroJoe » Thu Jan 19, 2012 5:59 pm

Look forward to the results
Here are the jar dimensions I have when doubled. The only dimension I cant find is the length of the internal duct, here I assumed it to be near the largest diameter. Makes it just under a 6" by 12" jar.
Attachments
TIMES2.JPG
CLICK TO ENLARGE

metiz
Posts: 1517
Joined: Fri Apr 21, 2006 6:34 pm
Antipspambot question: 125
Location: Netherlands

Re: Odd Metal jars

Post by metiz » Thu Jan 19, 2012 6:32 pm

I think I still have the dims somewhere for that duct, or at least the duct for my build. I'm not on the pc where the drawing's at so it'll be a couple of hours. I'll give you a heads up though: running this thing on gas is a PAIN. I got one of those valves from Nick as well; It's very sensitive but also a pain to controll. Again, when running gas it want SOME cooling, but not too much. I had the best results when the water exit pipe was belching out mostly boiling hot water and steam, instead of just luke warm water.

use a aquarium pump for your water supply, but raise the jar a bit so the pump's got to work to get the water up there. That will ensure a "hot cooling"
Quantify the world.

metiz
Posts: 1517
Joined: Fri Apr 21, 2006 6:34 pm
Antipspambot question: 125
Location: Netherlands

Re: Odd Metal jars

Post by metiz » Fri Jan 20, 2012 12:36 am

well shit. can't find the drawing
Quantify the world.

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Fri Jan 20, 2012 1:40 pm

PyroJoe wrote:Look forward to the results
Here are the jar dimensions I have when doubled. The only dimension I cant find is the length of the internal duct, here I assumed it to be near the largest diameter. Makes it just under a 6" by 12" jar.

Thanks for that Joe, iam not sure what size ill build to begin with!

Do you think a duct/diffuser could be benefitial for my thermo-jam. Iam starting to build a new one today.

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Fri Jan 20, 2012 1:44 pm

metiz wrote:I think I still have the dims somewhere for that duct, or at least the duct for my build. I'm not on the pc where the drawing's at so it'll be a couple of hours. I'll give you a heads up though: running this thing on gas is a PAIN. I got one of those valves from Nick as well; It's very sensitive but also a pain to controll. Again, when running gas it want SOME cooling, but not too much. I had the best results when the water exit pipe was belching out mostly boiling hot water and steam, instead of just luke warm water.

use a aquarium pump for your water supply, but raise the jar a bit so the pump's got to work to get the water up there. That will ensure a "hot cooling"

well shit. can't find the drawing
Nevermind, maybe they will turn up one day adnd its probably best if i have some things slightly different so that we get varied results.

I wonder whether the belching steam could run a steam engine :lol:

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Fri Jan 20, 2012 2:04 pm

I made a huge school boy error with with my augmentors, i have fitted the augmentors parallel to the exhuast. But they need to be perpendicular to the cone angle. basically the augmentors were in the wrong place and had very little effect. However there is an improvement in thrust, from the tail, without a doubt and the engine appears stronger!

Also i had actually forgotten to take the augmentors home from work so i knocked up new ones. i only had 4 inches of material so they had to be 2inch long each side.

Image

Image

Image

Heres the videos.
http://www.youtube.com/watch?v=6-DTwS7u ... 2HphCGHeNi

http://www.youtube.com/watch?v=X-iDFw_9 ... P9TDDQKY0L

This last video is the longest run so far for the thermo-jam. 80secs.

http://www.youtube.com/watch?v=qkijCVW2 ... gDbVCKb9wD

Tried to add a little propane again, but still struggling with the application of it. I think these thermo-jams will stay on meths, they run well and i have got good results so far from my primative testing.

Today iam testing out my new fuel cell. Its a butane canister for camping that has a needle valve in the top. The idea is to either run the cannister inverted with the air valve in the top, or run a syphon tube and have it the correct way round.

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Odd Metal jars

Post by PyroJoe » Fri Jan 20, 2012 2:57 pm

no worries metiz, Thanks for looking.

Those augmentors should be parallel to the tail just as they are. The opening close to the jar could be cut at the angle of the surface of the port to best capture the pressure. What happens in those augmentors is part of the pressure is captured and used to accelerate trapped mass, as the mass is accelerated it picks up a vector, and we want that vector to point straight back, just as you have it.

If the longer augmentors continue to do well at reinforcing the tail thrust, it could probably handle a slight tail expansion in the back 1/3 of the tail.

Dont think a internal duct in a thermo jar would do very well.
good work on a first go of it. :D

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Fri Jan 20, 2012 8:08 pm

Yes thanks for looking Metiz :)

Ohh its lucky i managed to check for new posts before i made any changes, i luckily read your post about 10mins before i intended to cut up the augmentors. Iam really starting to get my head around the theory, now that i have more understanding.

http://www.youtube.com/watch?v=C7Gkxlxj4RQ

I will read more on augmentation and vectors ect Thanks for setting me straight. The angle cut makes a world of diference as far as i can tell by ear and by feeling the tail thrust.

If i remember correctly, i had the augmentors right up close too start with (between 8-9mm) and its wouldnt really fire or sustain very well, it ran for 15secs and cut out abruptly. i moved them out to about 10.5mm and it fired up and sustained and ran as norm, but louder, faster and more powerfull.

Its a shame because i ran out of time today, i had to take a car too the scrap dealers. 145gbp richer now though.

Image

Here is the pressurized fuel tank. it needs some work on the welds though because it isnt holding air pressure. Hopefully tomorrow we will have a result!

Image

Image

I have to wait until tomorrow until i can test the 100mm augmentors. This time though i brought back more materials so that i can try lots of different lengths. However this is hard work without a method of measuring any changes that i make. I need a seriously low resistance rig. I may try hanging the jet on wires so there is less stiction and resistance too over come.

Ill go and buy some more materials in the morning so that i have the option too add a tail expansion. Would you say 2 caliber is good or should i try a smaller expansion first? and ill just do the last 33%. would you say 33% expansion + 9* cone or 33% including the cone?

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Odd Metal jars

Post by PyroJoe » Fri Jan 20, 2012 9:39 pm

Those angle cuts look good. 8)
Typically I see how it does with a 1.25 caliber expansion then test and increase it. There is a simple way to cut long triangle from one side of a oversized pipe and hammer it shut to match the tailpipe diameter.
I guess I should do a write up on that.

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Fri Jan 20, 2012 10:14 pm

PyroJoe wrote:Those angle cuts look good. 8)
Typically I see how it does with a 1.25 caliber expansion then test and increase it. There is a simple way to cut long triangle from one side of a oversized pipe and hammer it shut to match the tailpipe diameter.
I guess I should do a write up on that.
Thanks and just too note, i have 8mm inlets and 9mm x 50mm augmentors at the moment about 10-11mm away from the port.

thanks for the tip for fabricating the expansion, i actually used that method to build all the cones on the small pulsejet i built, i think its a thermojet with a chinese style tail, iam not to good with the different types ha

first i need a method of testing. i would like to get an idea of output as it is now. then i can make changes to the augmentors, cc, tailpipe ect ect.

Any ideas? maybe i could set up a wind vane to compare changes or maybe hanging from wire with digital scales.

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Sun Jan 22, 2012 9:49 pm

I built another thermo-jam

https://www.youtube.com/watch?v=9HilIjN ... ata_player

It could work well once I have played with exhaust length and intakes + intake augmentors.

Dims are

Cc 50mm id x 100mm with convex cc end
Tailpipe 14mm I'd x 585mm
Inlets 2 x 8mm

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Odd Metal jars

Post by PyroJoe » Mon Jan 23, 2012 4:48 pm

looking good, neat little vip sound there at the end.

JamesD did a nice thrust stand with a DIY air table, lifting a mass with string and a pulley. Maybe if the air table could be substituted by hanging the engine from some longish string/wire, it may do well.
The problem is the mass of the engine compared to the thrust production. Nothing to get discouraged over, just keep it in mind.

Small gains in small engines don't "represent" as well as small gains in big engines.

kevin lee
Posts: 100
Joined: Mon Dec 05, 2011 3:54 pm
Antipspambot question: 125

Re: Odd Metal jars

Post by kevin lee » Mon Jan 23, 2012 5:17 pm

Yes i understand that the mass out weighs the thrust, iam not too bothered at all really, i just need a comparison for my mods. i like the air table idea alot, especially if the mass upon the table was equal to a finished model boat or car.

I like the ease of fabrication and the fact i can run them in my shed on methylated spirits :D

PyroJoe
Posts: 1743
Joined: Wed Aug 29, 2007 5:44 pm
Antipspambot question: 125
Location: Texas

Re: Odd Metal jars

Post by PyroJoe » Tue Jan 31, 2012 10:24 pm

Still working on the double scale jar. Lack the internal duct and to cut the port. Should have it together by next weekend, probably test the weekend of Feb 11-12 if the injector goes together well.

Post Reply