Posted: 10/15/2004 4:44:53 PM EDT
| I got the basic idea, but how the hell do you keep the fire going? I hear there is a shroud or something. I want to build a little one (in a real thick housing) maybe a few inches round just for kicks. I probably wont, but I think it would be entertaining. |
You keep feeding it fuel. Just like your IC engine. |
Not quite the same. A jet engine will self-sustain so longer as there is fuel and air. No spark plugs or ignitors (afterburners aside). Pressure and heat keeps the fire burning, LOUDLY! |
And the real power and thrust come from the way the air moves through the unit, like a water turbine. |
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Designing and building burner cans might be the real trick to getting jet engines to work - it's probably more art than science. Look around the net for plans. The only set that I've ever seen that were legitimate were from Marquardt, and you have to scale and derive dimensions from those! Do a search on "how a jet engine works" for all the info you can stand. www.ueet.nasa.gov/StudentSite/engines.html www.ueet.nasa.gov/ |
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How Gas Turbine Engines Work travel.howstuffworks.com/turbine4.htm |
| They now make mini jet engines for RC aircraft. It would be easier to buy one. You could always try building a pulse jet engine. I've seen a few shows where they did this (Junk Yard Wars comes to mind). The pulse jet is the same motive power used on the V-1 buzz bomb and our early post-war cruise missles (German copies). |
He said how does the fire keep going, not how did it start 
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WTF did that SAAB hit? Snap-On tool box? BTW Here's the first plane I professionally worked on. It was powered by good Pratt & Whitney engines!!!!!!!!!!!!! 
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CV540 or 580? I'm not an expert on them but my Dad worked on them for Aspen, Frontier and Air Wisconsin Airlines. |
| Well you start the engine through bleed air, and it begines to spin the turbine and the fan, then you shoot Jet A or any other jet fuel into the combustor can and you set the Ignitor plug off. Think of the ignitor plug as a spark plug on steriods. After the fuel ignites and the engine has spooled up to the proper percent the ignitors are shut off. Its been a while since I have gone over this in class but thats what i remember. Also when I took propulsions the instructor said he had a student who took a turbo charger and used that for the base to build on for the engine so might want to look into that. |
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Think of it more like the glow-plug from a diesel engine. The first turbines were designed from centrifugal turbocharger/superchargers
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Yeah should have used the glow plug instead my mind wasnt exactly turned on at the time lol, But do you remember how many volts they run on for some reason I cant however I had another instructor bring in a battery pack and the ignitor assembly and put they juice to it boy did that thing pop also it puts out a pretty descent spark or it appeared |
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last jet engine I worked on was a PW4000 series (on 777's). talk about a lot of suck and blow.. Fortunately, my prediction that w/in the first year of service, these babies would injest someone, was wrong. I guess they've kept up a pretty healty respect from the begining. |
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On the A-3 it is 28 volt DC from either the essential or monitored DC bus, or else 24 volt (battery) from the emergency bus. On the C-130 it is 28 volt DC from the essential bus or 24 volts from the battery via the battery bus and bus tie. Can't talk about the E-6. On the A-7's we could do a no electrical power start if we used a "piggyback", three 9 volt batteries tied in series. Disconnect one ignitor lead, then switch the generators on, hook up external start air and pressurize it. At 67-74% hit the ignitors (tach generator driven), fire the engine, generators come on line, hydraulics come up. Remove the piggyback, reconnect the ignitor lead and your done.
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There was someone selling plans on ebay on how to make a jet engine out of a truck turbo charger. It looked pretty cool, i found it while searching for a lycoming .Also found these. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=2494533675&category=26441 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=36631&item=2494610690&rd=1 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=2567&item=5927735773&rd=1 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=2567&item=5927162476&rd=1 http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=2594&item=5927010311&rd=1 |
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Make a nice shroud around the compressor blades.. if they lose balance, or what not and break apart.. the who thing will disentigrate and fly outwards... cause they spin at.. oh.. i have no clue.. 10,000 rpm or more.. 60,000 rpm? And you'll need to spindle them up to about 5,000 rpm to start them.. or something like that... Jet engines are 'simple' when running, but getting them running is harder.. I have no idea really, what i am talking about. 
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CV-440 In the pic. 2 Pratt and Whitney R-2800 Double Wasp 18 cyl radials (note the cowl flaps). When those things started to pull 36-42 inches, you really had to be on the brakes. The CV-540 IIRC was a CV-240 reengined with T-56 Turboprops (same eng on the C-130), and the 580 was a 440 reengined the same way. There are also CV 600's and 640's that are reengined with the Rolls Royce Dart Turboprop. Rhoades was just bringing those on line, when I left for the Big D. BTW I'm only 25, that pic was taken before I worked there, but N157JR definetly was one of my favorite birds out there. How many 25 year olds do you know that did radial work and got paid? One funny thing about when I was hired on at Rhoades, shortly after I started, I was given a DC-3 elevator with a tear and told to fix it. I was ridiculed a bit when I asked for some help doing dope and fabric, but I had to explain that my class was the first one that didn't do dope and fabric for my A&P. The school replaced that with a larger and more comprehensive composite class. |
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Dammit man I love jet engines...spent 8 years in the USAF and the last 5 working at Ft. Rucker as civilian chopper mech. So what do you want to know no bullshit here dude, no theory, just practical application! The actual burning of the fuel takes place in the combustion chamber and that is right aft of the diffuser chamber. The combustion chamber allows the fuel mixture with the high velocity and high pressure air to mix and combust. After the initial combustion is started with the igniter plug(s) and the engine comes up to speed the igniter is no longer needed. The fire is not necessarily self supporting as you can stall the compressor and blow out the fire(flameout) What causes the combustion sequence to remain in effect is basically the actual compression of the air through the compressor section. Normally the higher the compression ratio the hotter the air. As the air is compressed it will become extremely hot due to friction. Enough compression and the air will become hot enough to sustain ignition...ever heard of a ram jet? Ok, so now you are flying in a thunderstorm and there is turbulence and water ingestion...what due you do? Turn on the contunuos ignition...fires the igniters in sequence to maintain reliable ignition. Most of the time I have ever flown on military jets we always had it on during landing, especially during a formation and landing behind other aircraft. Turbulence from the lead a/c can give you a compressor stall too. Wes |
Did someone say combustion chamber?  Multiple (Can) Chamber Used mainly in association with a centrifugal flow compressor, this type of burner consists of several chambers disposed radially around the engine. Each chamber has an individual fuel nozzle, a flame tube and an air casing. The different flame tubes are all interconnected. Compressor discharge air is guided by ducts into the individual chambers.  Can-Annular Chamber This type is the most widely used in modern jet engines. It consists of several flame tubes in a common air casing.  Annular chamber This type consists of a single flame tube and fuel nozzle. It has a greater power-to-weight ratio than the multiple chamber system. |
those things have very little power- fyi. |
Yep not bad experience for being 25. I never got any real radial experience, but off the top of my head, this is the oldest thing I've worked on. I helped do a full restoration on this Cub when I worked in Germany.  |
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Jet engine beer cooler: www.asciimation.co.nz/beer/ The turbo charger jet engine: asciimation.co.nz/turbine/ |
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Burning cat to toss into the intake? Sounds good to me dude. I have seen what a goose can do but methinks a good old burning cat would be much more fun. So is there an application I can fill out or can just anyone hire in to that position Nice Cub by the way. And nice engine combustion chamber pics as well. We had a C-141 come in one night and hit a deer on landing...ripped the bottom of the fuselage open almost all the way back...kinda like a zipper. Took almost a year to fix the sheetmetal and structural damage. I like airplanes Wes Edit: forgot to mention:the kid with the rocket pointed at his ass is gonna be in big trouble if the mounts break loose...he is either a dumbass or an excitement-junkie-homo  |