New... big...ramjet (plans-movie to come)

Moderator: Mike Everman

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

New... big...ramjet (plans-movie to come)

Post by Irvine.J » Sun Aug 20, 2006 5:07 pm

Hail all, I have built a ramjet that is about to have its front nozzle welded on, and I have made a video of it with pictures for you all to see. (This engine is complete) However before I go ahead and fire it up i'm just waiting on some feedback from one of the pro's. Anyway till such time, here is the plan I made up for it. Should be very interesting, anyway, some big long video's will be made for ya'll if it works.
Comments on the plan? You'll see a video of it shortly.
Peace as always,
Mangy.
Eric, mike and larry- you have recieved PM's To the video link for inspection before posting it. Awaiting feedback.
Attachments
Mangyjetplan.JPG
(50.89 KiB) Downloaded 1141 times

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Sun Aug 20, 2006 5:37 pm

Here are the photo's of the engine. Cant wait to fire it up! (The nose cone is off to show the flameholder etc. At this point I am aware I need to do some grinding to clean it up a bit :)
Attachments
JET 014.jpg
(308.38 KiB) Downloaded 1030 times
JET 019.jpg
(293.95 KiB) Downloaded 975 times
JET 015.jpg
(289.42 KiB) Downloaded 1091 times

Zippiot
Posts: 1190
Joined: Tue Nov 15, 2005 7:55 pm
Antipspambot question: 0
Location: california
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Zippiot » Sun Aug 20, 2006 9:13 pm

What are you using as an air source? Looks nice, I need to get off my butt and build a good one (or at least get up a vid of my modified muggs running...)

Thats It I'm ordering a welder now!
Sailing Student- How do I know if my life jacket is tight enough?
Me- Can you breathe?
Sailing Student- Yes
Me- Then its too loose!

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Mon Aug 21, 2006 2:28 am

PETROL BLOWER muahahah! 1.5 hp or so i think - Pretty decent one too, just putting some final touches will start her up soon.

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

Re: Photo's of complete jet

Post by Irvine.J » Mon Aug 21, 2006 6:36 am

Some more photo's of the complete ramjet!
Video to follow shortly, about to try n get it running... Can you feel the tension in the air... nail biting stuff!
Attachments
JET1 002.jpg
(250.86 KiB) Downloaded 920 times
JET1 001.jpg
(313.94 KiB) Downloaded 974 times
JET1 003.jpg
(296.46 KiB) Downloaded 900 times
JET1 004.jpg
(263.94 KiB) Downloaded 902 times

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

Ramjet movie part I of 3

Post by Irvine.J » Mon Aug 21, 2006 8:42 am

I should have posted that movie link here sorry...
LET ME KNOW WHAT YOU THINK OF THE AWESOMENESS OF MY MOVIE MAKING SKILL MUAHAHAHA!
Comment the preverbial "crud" out of it, keen to hear feedback! It also has a killer sound track!
MOST OF ALL- ENJOY!

PART I - "I've created a MONSTER!"
http://www.metacafe.com/watch/216179/ma ... al_ramjet/

TOMORROW- PART II "MANGY GO BOOM!"
link to be posted.

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

re: New... big...ramjet (plans-movie to come)

Post by larry cottrill » Mon Aug 21, 2006 12:39 pm

I like it very much !!!

Fantastic film-making (well, fantastic for low budgets, anyway) - ha ha!

It looks pretty good. Without dimensions, it's hard to judge the effectiveness of your diffuser/flameholder section, which is really the key to success. My only real criticism is that I think the combustion chamber is a lot bigger volume (because of its length) than it needs to be, which makes me think that you may lose efficiency (as if that meant anything - ha!) getting the burned gases to the nozzle.

I can't wait to see/hear this sucker run - great job!

L Cottrill

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Mon Aug 21, 2006 2:28 pm

Haha Larry- Thank you very much for your kind words of support and I shall be firing up this sucker in exactly 10 hours from now! I'm glad you enjoyed the movie larry, and thankyou for your feedback, i'll get you some dimensions real soon! Thankyou again for your feedback as its much appreciated!
Regards,
Mangy

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

re: New... big...ramjet (plans-movie to come)

Post by larry cottrill » Mon Aug 21, 2006 2:50 pm

Number47 -

I hope your blower is up to the job. I guess 1.5 hp sounds pretty big, so it might do all right. Do you have any idea at all what air speed it's supposed to be able to deliver?

What I'm worried about for an engine this size is that you might need all your air for driving it, with none left over for flow-around cooling (if you even care ;-)

L Cottrill

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Mon Aug 21, 2006 4:33 pm

Well larry, as far as i know its pretty high power, at max throttle if its not secured down it will blow itself up and over, quite funny really.
I can run a couple of large fans around the engine for added cooling, though your right i'm not too worried at this stage. I did modify the output cone for it so it slenders down into a smaller nozzle,(apparently that will increase the airspeed but its pretty hardcore already. (Its on the video) so i guess I'm not really too fussed about the external cooling, but I am now, I'll figure something out. 8 Hours gentlemen, then, like the video said, we shall see. I have made the second video, and am now just waiting for the footage of it running, the next video... is totally spectacular!! HAHAHA! I will keep you informed, and up to date as soon as it runs.
Peace.
Mangy
Can I have a countdown please gentlemen! LOL

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Mon Aug 21, 2006 5:42 pm

Larry, do you think its low airspeed performance will be increased, and its efficency not too much a loss because of the impeding centre "rocket shaped thing" If you look down the back of it, there is really only 2 cm on each side that the gas can travel past. I was hoping it would help low speed combustion and slow the air down as its mixing and combusting, then hopefully allowing for more time for hot gas expansion within the engine before its all pushed out... what do you reckon?

Also, the front of the "Rocket shaped thing" that I just for whatever reason now call the "Impeder" begins right at the end of the difuser, so the relative space between the flameholder and the start of the "impeder" might only be about 5/6 cm. Do you understand or did i explain that really badly? I suck at explaining things well. Anyway, that was the idea, I'm now thinking my defuser might need to change orientation, but its too much work for now, and i just wanna light the mongrel up. Wish me luck... where is einstien when you need him!

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

re: New... big...ramjet (plans-movie to come)

Post by larry cottrill » Mon Aug 21, 2006 8:16 pm

What you want in a diffuser is for the cross-sectional area to gradually increase as the air flows farther in toward the flameholder. With a low-speed diffuser, the increase won't be a huge percentage because we can't achieve a huge ratio of final pressure to inlet pressure.

Oh, here's another important point: Make sure there is a gap between your blower nozzle and the ramjet inlet. The reason is that if you butt the two together, tightly sealed, you will have lower pressure at your inlet because of the velocity, i.e. the nozzle and the diffuser will create a venturi with its associated pressure drop. If you leave a significant gap, the stream from the blower will take in some outdoor air and come back to outside air pressure. Of course, this will slow the stream somewhat, but not enough to take away the advantage you get by allowing the pressure to be restored. A few cm of gap should be plenty to get the job done.

L Cottrill

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

Quick question on the Mangy-jet

Post by Irvine.J » Tue Aug 22, 2006 2:17 pm

People, the ramjet seems to be working properly and I am working on the video as we speak, yet need more footage. I was wondering, if the engine glows pink does that mean its hotter then your average red? I mean its BRIGHT FREAKING PINK! It looks beautiful!

Also, are the colour of flames out the back dependant on the fuel you are using, or the heat of your combustion chamber? The flames out the back started off as blue and kind of looked and sounded as if (on lowish airflow with not too much gas) it was recipricating kind of like a PJ (Not nearly as loud though), and as the heat of the engine increased, the tailpipe flame became more yellow... nice and pointy. Should the colour of the flame change like that? I did get some bunsen action which scared the crap out of me on video, very funny when a huge yellow ball of fire nearly engulphs you! I havent yet gunned the crap out of it but will do as soon as I know this...

IMPORTANT FOR ME TO KNOW ::: When you want to throttle it right up, do you increase gasflow or airflow first, or both at the same time???

larry cottrill
Posts: 4140
Joined: Sun Oct 05, 2003 1:17 am
Antipspambot question: 0
Location: Mingo, Iowa USA
Contact:

re: New... big...ramjet (plans-movie to come)

Post by larry cottrill » Tue Aug 22, 2006 2:26 pm

Yellow flame? MORE AIR! MORE AIR!

As far as I know, for "ordinary" hydrocarbon fuels, the flame color is basically a matter of temperature - the bluer it is, the hotter. "Exotic" fuels tend to have more the characteristic color of the chemical elements involved - a hydrogen flame is basically pink or red, for example. Jet engines are run on "the lean side of the power curve", meaning that within limits, richer fuel/air mixtures should deliver more power than leaner ones. Going too rich (yellow flame) defeats this theory, though, because combustion takes place too late (expansion behind the chamber instead of inside it) and consequently lots of fuel wasted. I think in most cases, you want to get to a flame where yellow is starting to show, then back off a little on fuel until the flame gets blue and pulls forward a bit.

I would throttle up by increasing fuel, thus richening the mixture, THEN add more air until you restore blue flame (IF you can get there!). Throttle down by cutting down the air first, again richening the mixture, then cut down the fuel (lean it out) to restore blue flame.

The problem with throttling ramjets is getting flameout because you're suddenly running too lean. The remedy is to throttle toward richer mixture, then lean it out appropriately for the new power level. Early turbojets had the same problem (Germany's ME-262 fighter) - if you tried to cut the throttle back quickly, everything died.

Sounds like you're making great progress! What do you think of the noise?

L Cottrill
Last edited by larry cottrill on Tue Aug 22, 2006 2:34 pm, edited 1 time in total.

Irvine.J
Posts: 1063
Joined: Mon Jun 05, 2006 4:28 pm
Antipspambot question: 0
Location: Brisbane, Australia
Contact:

re: New... big...ramjet (plans-movie to come)

Post by Irvine.J » Tue Aug 22, 2006 2:31 pm

Larry your my hero, that was very well explained thankyou so much! The noise is amazing, it totally overwhelms the petrol blower! Even when its on minimum air and little gas that blue pointy flame shakes the camera. I freaking love this engine, I cant wait to show you guys the video, you going to love it! It is now 12:30 at night and I think i should lock up the lab and prepair some notes for a big day tomorrow. Larry your the man, thanks for your help!
MANGY-JET PART II... Coming tomorrow to the Pulse-jets.com cinema on your computer! LOL
Larry I'm emailing you 2 short video's right now for you to inspect the idling and when it starts getting hot, please PM me some comments- or a little advise... am i on the right track?

Post Reply