The Great Ramjet Challenge!!!

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redneck
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Post by redneck » Thu Jan 25, 2007 3:22 am

haaahaahaa!!!!! (snort) heeeheee lol that is so dang true man, i got the same lecture from my wife. and i caint even argue, cuz its true.... lol said i try to get the jet to put out (thrust) more than i am interested in... well yall figure that one out. what do you say? your right honney... im just too busy at night, now please leave your blocking my light.
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Thu Jan 25, 2007 5:37 am

Take her out to a dinner that costs more than the jet, just leave the reciepts casually where she sleeps and when the jet is finished make a big not on how little it costs, say "That was cheap fun, look it even costed less than dinner!"

Reading that its prolly not a good idea, involve her maybe?

Well if you guys need an extension (propane+cold weather=no fun, but kerosine is good until way into the negatives) surely the rest of us can let the games go on for a while...
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!

redneck
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Post by redneck » Thu Jan 25, 2007 5:46 am

you know.... it would help and would have been great advice IF my wife didnt read this board too...
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Thu Jan 25, 2007 5:49 am

So edit that?

Got my jet all drawn up ready to be cut out.

My current projects not including school:
1-turbine
2-oil burning furnace
3-ramjet
4-pulsejet
5-valvless pj
6-valvless pj with rammy[s]
7-r/c plane

Not in any rank, mostly working on turbine furnace rammy and plane.
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!

redneck
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Post by redneck » Thu Jan 25, 2007 5:57 am

yo zippy.... if you get this little turbine going pretty good, i will pay you to make me one or 2. let me know if you wouldnt mind???
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Thu Jan 25, 2007 6:06 am

I would gladly build you one but chances are it will fail much before any other one would. Also performance would be much lower, my best suggestion is to pay the 20 bux for the shrecky book and learn how to do it. It can even be done without a lathe if you have a pedestal grinder and a vice!!


And there is always the possibility of it killing you and everyone around you...

Well me finishing it is prolly a month away, I need to finish my furnace and make 2 good turbines with the blades from it. Then fit the shaft to the bearings comrpessor and 2 turbines, finish the CC flameholder vaporizer and ngv. Might make a new compressor at a different design to get bigger pressure gains.

I will keep you posted in the turbine build thread, its called building the shrecky and can be found in the turbines section.

I could draw up a set of plans, I even have the formulas I need to make an axial stage[s] or a turbo-fan that could be attatched.
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!

redneck
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Post by redneck » Thu Jan 25, 2007 9:49 pm

sorry, didnt mean to carry off topic......
hooowee that was loud! do it again!

Zippiot
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Post by Zippiot » Thu Jan 25, 2007 9:56 pm

Dun worry bout that, off topic is fine thread jacking is punishable by death!!!

I placed my big piece of steel right in the hallways so I will trip over it until I cut it up...gotta find some steel tubing I think copper might melt...
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!

Jim Berquist
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Ram build

Post by Jim Berquist » Thu Jan 25, 2007 11:55 pm

Yes ::::: Reprieve!!!!!! I have more time..




Jim
WHAT TO FRAP, IT WORKED![url=callto://james.a.berquist]Image[/url]

Najm
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Post by Najm » Mon Jan 29, 2007 7:05 am

I recently made a ramjet from an aerosol can and aluminium. One of my best builds so far...

Intake dia=3.75 cm, length=18.6 cm
Combustion chamber dia=7 cm, length=11.5 cm
Exhaust dia=4.4 cm, length=4.85 cm

Runs pretty well, and there is no heating on the walls of the ramjet.(I am thinking even if the whole ramjet was made out of alu it wouldnt melt).
Most of the flame is confined in the combustion chamber when running on full throttle. Running on methane gas from main supply.
And I havn't measured thrust, any cheap AND easy way of doing it??

Have posted pics for the first time.
The last pic should have been first.
Attachments
DSC01099.JPG
Ramjet running..... not at full throttle ..
DSC01099.JPG (58.9 KiB) Viewed 9384 times
DSC01100.JPG
Throttle increased.... tiles are on the ramjet to hold it in place, b/c if the blower gets out of line it gets blown away
DSC01100.JPG (57.89 KiB) Viewed 9384 times
DSC01105.JPG
At full throttle, in no light conditions, flame is mostly confined in the cc.
I'm sorry if nothing is visible
DSC01105.JPG (31.7 KiB) Viewed 9384 times

Eric
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Post by Eric » Fri Mar 09, 2007 5:00 am

Wondering when the deadline is going to be?

I ask because I just made another TP-180-70 and have a sheet of 20 gauge mild steel sitting around and I think I am going to make a 20" diameter ramjet for the tailpipe for it. Think im crazy? Your damn right im crazy :D

I am going to be hiding behind my 5/16" steel plate bunker before I flow any propane into the big ramjet. The deafeningly powerful eplosions made from over fueling the little ramjet while the TP-180 was on full throttle definately demands respect and safety.

Any predictions on thrust? Flame length?

Eric
Image

Talking like a pirate does not qualify as experience, this should be common sense, as pirates have little real life experience in anything other than smelling bad, and contracting venereal diseases

heada
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20" ramjet

Post by heada » Fri Mar 09, 2007 5:27 am

Based on 20 inch diameter, you'll have 89.714 inches of entrance area (Thats frickin' huge!!) and being made out of 20 gauge MS (at 0.0104 lbs/in^2) it should come in at near 52 pounds(excluding fuel and flame holder as I don't know what the surface area of the flame holder you are going to use). Assuming an intake air speed of 410 mph, it should produce about 130 lbs of net thrust. With an intake airspeed of about 680 mph (approaching supersonic, where ramjets work better) you should have a net thrust of about 400 lbs. Lower the intake airspeed to just 270 mph and you should see about 40 lbs of net thrust.

Here are the figures I used:

Diffuser Entrance Area: 89.714 in
Diffuser Entrance Diameter: 10.690 in
Diffuser Exit Diameter: 20.000 in
Diffuser Length: 17.732 in
Diffuser surface area: 1841.680 in^2

Combustion Chamber Diameter: 20.000 in
Combustion Chamber Length: 32.071 in
Combustion Chamber surface area: 2015.096 in^2

Nozzle Entrance diameter: 20.000 in
Nozzle Exit diameter: 14.967 in
Nozzle Length: 10.690 in
Nozzle surface area 1134.245 in^2


Please, oh please make video of this (from a safe location!) and figure out a thrust gauge to see how close my numbers are (compiled from several sources)

-Aaron

Eric
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Post by Eric » Fri Mar 09, 2007 5:54 pm

I will definately get video of it, but its mild steel so Im not sure how long its going to last.

Eric
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Talking like a pirate does not qualify as experience, this should be common sense, as pirates have little real life experience in anything other than smelling bad, and contracting venereal diseases

heada
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Post by heada » Fri Mar 09, 2007 6:15 pm

Max burn temp for propane in the method we use it is normally between 2500 *F and 2800 *F 20 gauge mild steel should be able to handle that for at least a few minutes and if you get any kind of air flow to cool it, it could last much longer. If you go with kerosene, I'd cut the time by 1/3. Try for LH2 and you'd be lucky to get 5 minutes...but what a wonderful 5 minutes those would be.

Any chance you have a thermocouple that you could attach and get an actual temp reading? A pressure transducer mounted in the diffuser/cc/nozzle areas would be really cool too.

-Aaron

bhupendra741in
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hiii.....just look at the design nd suggest me changes...

Post by bhupendra741in » Tue Aug 14, 2007 6:11 pm

hiii......i am just a biggner as far as ramjet is concerned.......so please help me out......i've prepared a design just hav a look at that nd then help me out with som more changes in it...........one thing which i m thinking is........i am getting soo much pressure...that if i change my nozzle design from converging to converging-diverging nozzle ....then it may give upto 3 mach........so gimme yr commnets for that.....I have prepared a new design which i am mailing you. Dimensions and readings are as follows:-
Diffuser Entrance area :- 706mm2
Diff ent dia :- 30mm
Diff length :- 50 mm is ideal ....i have taken 59mm
Diffu exit dia :- 51mm
CC length :- 110 mm
Nozzle exit dia :- 42mm
Nozzle length :- 40mm
A1= 706mm2
P1=1.10325bar
T1= 303K
V1= 140 m/s
P2= 1.21 bar
T2= 311K
V2= 43.34m/s
P3= 49.11 bar
T3= 896K
mass flow rate of air = 0.116kg/sec
fuel supply = 7gm/sec
Fuel Used = Propane
CV= 45000KJ/kg
But as per this design I can even get speed upto 3mach if I will change nozzle design from Converging Nozzle to Converging-Diverging Nozzle. So shall I do that.[quote][/quote]
bghblj

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