The Great Ramjet Challenge!!!

[Zippiot]

Eric, your pj vs our rj's, sound good?

Still 5:1 power to weight is what we are looking for.

Bonus points for the biggest flame shooting out the back!!! haha


I started work on my jet late last night, got 2 finals today then the rest of the year to finish my jet. I am doing [the part I am working on] incorrectly, or at least not the standard way. Hope it works.

[Jim Berquist]

The Cheat:

Would I be allowed to fasten the Ram-Jet to the P.J. as a augmentation system?

If I could prove that the Ram-Jet achieved the 5/1 thrust to wieght in conjunction with the P.J.???????

I want combined thrust? Augmentation.....A sort of after burner with less fuel consumption.....

Fact is you would most likely loose as much from the P.J. as you gained from the Ram-Jet. What if it became a sort of super after burner set up?

Yet again one may be able to find a ballance and conbine the two outputs.

What if You could achieve the 5/1 plus the output from the P.J. with little loss.....Sweet!!!!

I think it could be done! Secrets in my pocket!!!!!!

People tend to over complicate things some times!



Jim

[Zippiot]

I dont know if the ramjet works just like a pj augmentor...

Well draw a pic so the people with more knowledge could chime in.

Larry (or at least I think it was you) a logn time ago I remember a little ramjet you made out of paper cups. It had an interesting flameholder design, if you still have the pic could you elaborate? Or if its the wrong person...my mind is fading.

[Zippiot]

I wonder...

Kinda confused on what you want to do with a pj and a ram..

[larry cottrill]

Larry (or at least I think it was you) a long time ago I remember a little ramjet you made out of paper cups. It had an interesting flameholder design, if you still have the pic could you elaborate?

These are the classic textbook flameholders - little hollow cones, like "mini diffusers" that really crank down the speed of the air that gets through them. They create considerable effects such as turbulence and shear, but quite localized. They are very small in proportion to the whole cross-sectional area in which they are located, and are pretty low drag. I show two, side by side, but most real jets would have a ring of four or some such.

They don't really look like much in the picture. They are mounted on a couple of thin transverse struts (round toothpicks in the model).

L Cottrill

[Zippiot]

Oh so its a bunch of little conical baffles? Cool!

Thanks

[Jim Berquist]

Looking at a Hybrid P.J. Ram at the moment...May find a way to complete the undo-able.......Jim

God I wish I was smart!!!!!

Jim

[Zippiot]

Messerschmitt made a valveless pj that could sustain ram operation.

Cant find any info on it though...

[thecheat]

well... I just got some metal scraps... (all stainless!) but the big issue I'm running into is: dang... if I make a ramjet outta these this thing'll weigh forty pounds!

What I mean is this... the fabricator had just dumped their scrap bin, so, they had very little thin stuff. I was able to pick up ONE small, 1 1/2 sq ft of 20 gauge. the rest is 18 gauge... this stuff is blasted hard to bend! The pipes I got are all nice, heavy, 16 or 14 gauge...

so my thoughts are this- wow... 5to1 thrust to weight ratio is pretty big! not because it's impossible... but because of the materials at hand...

I think I'm going to make something really odd now... like no ramjet ever seen!

PS: oh, and I had better go stock up on some drill bits and cutting wheels... I hear stainless is a little harder than mild steel...

PPS: oh, and James, what was that thing you used that was attached to the end of your drill. The thing you were cutting the metal with?

[Jim Berquist]

Here Eric:

This is what I would like to try.

The Jet stream coming from the P.J. to the most part has been precombusted as per say. This could cause a lack of O2 required to Sustain a Ram-Jet with full potential.

See attached drawing for the Idea.

My art sucks, But you should get the Idea.

Do you think the loss of thrust from the P.J. runing the Ram-Jet could be over come by the thrust of the Ram-Jet?

Jim

[Zippiot]

I am stuck...
Since the goal is power to weight of 5:1 A smaller ramjet would be the [obvious] solution. Also with a smaller rj the blower can be nozzled down...But I like my design at the moment and am having a hard time finding the power to put it on the backshelf...


ARRGGHH!!

[Irvine.J]

If we knew some people doing aeronautical engineering at uni would they have access to windtunnel or something so we could get them tested for free? Just tell them to say they made it? Just an idea, though I'd have no Idea if they can or can't?

[Zippiot]

I'm actually transfering to cal poly slo under mechanical/aerospace engineering next fall...its a while to wait to test my jet!

It seems we need a huge ducted fan or an even bigger leafblower (centrifugal blower) to make a windtunnel. Or we could find a bunch of 5hp vacumes and have them all blow into the same pipe (build a new unit so all three are no longer enclosed in their, well enclosure...), 4 or so should be able to make a 200 mph windtunnel with a cross section of about 8 or 9 inches. Probably would need 5 at that size, the more the better in this case.

I bet my friend working at Got Junk could fine me a few old vacumes!

I built a paper model of my new tiny ramjet, it is 7 inches long with a 3.5x2 inch CC. Intake is 1 inch diameter at a 15 degree angle, exhaust is 1.4 inch diameter at a 10 degree angle. Basic stuff, might make a spike [small] to cover fuel injection parts, no idea as to flame holder yet maybe a scaled down version of my 4 finger 30% CC area design. I think I can weld a nut to my flameholder and stick a little bolt covered in solid fuel. That would be a neat thing to test!

[Irvine.J]

If anyone has a flameholder config they want tested I'm about to weld up a small 10 inch (total length) ram like the one that had the huge blue tailflame, similar dimentions... size etc not required, just the general shape of the the flameholder/ angles etc. You have got about an hour or so then I'll just have to weld in something. (All the pieces are already cut and folded, just not a flameholder...so
GO GO GO!
Lol.

[Irvine.J]

Lol guys, the "MiniLance"
Hahah.
(though I probably will get rid of the spike, just wanted to see if I could do it.)

I have to cut a flameholder shape i'm just not sure, I'v got a much better nozzle on my blower now too...tomorrow will be a fun an exciting day.