Here's a trio of curated content from around the Web, showcasing videos of homebrew efforts to construct small jet engines. Two are made out of repurposed junk, while our cutting-edge first example is a student engine created using a 3D printer.
One would think such an engine, built by students in a Jet Engine Manufacturing Class at the University of Virginia's Mechanical and Aerospace Engineering Department, would melt. However, as Professor David Sheffler notes in this YouTube video, it's a demo engine. "We're using compressed air, instead of having an actual flame in there that would burn up our parts," he says.
The model is a dual-concentric turbofan. It's got a high-pressure compressor spun by a high-pressure turbine, and a low-pressure turbine spinning the fan up front.
Our next example is an oldie but goodie, in multiple senses of the phrase. It was designed by Dave Chovanak in 1965 when he was a student at Nevada Southern University. In the YouTube video, he says it was made with $85 worth of junk parts, including components drawn from a flower vase and Hoover vacuum cleaner, and has bearings made out of copper plumbing fittings.
The engine, called "The Rebel," is said to weigh 5 lbs. and deliver 8 lbs. of thrust. It spins at 35,000 rpm at maximum throttle. Unfortunately, the video doesn't show the completed engine or its operation.
The finished engine can be seen in Chovanak's Photobucket stream (click on the image below):
Our final video is a rudimentary jet engine constructed out of a turbo off of a Continental TSIO-520. The latter is a conventional piston aircraft engine from the early 1960s, made by Teledyne.
It's mounted on a test stand and, when lit, is satisfyingly noisy. However, it doesn't seem to deliver a whole heck of a lot of thrust. This one was uploaded to YouTube by kyleandellenb, with editing by Jonathan Santhouse.
Gadget Freak Jr. is an effort to broaden the range of projects we showcase by scouring the Web universe for interesting and relevant material. We'd like your opinions on this first offering, and we also welcome your contributions. Please write to me at firstname.lastname@example.org.
Credits: A complete story on the U. Va. student jet engine, written by Steve Rousseau, first appeared in July on Popular Mechanics. Our embedded video was obtained from YouTube, to which it was uploaded by Boricualn1707.
The info on the Dave Chovanak $85 "Rebel" engine was drawn from the video and the description posted on Batygoldfly's YouTube channel. The picture of Chovanak holding the engine comes from Dave's Photobucket stream.
Love this treatment. Very cool to see the juxtaposition of the jet engine created in the university setting, all buttoned up and produced (unbelievably so) with a 3D printer compared to the guy in what looks to be his basement with the 40-year plus crinkled up design plans. Either way, great stuff and a perfect way to showcase the back-room innovations happening every day.
It should also be noted that the use of small jet engines has become quite common in the model airplane field. Well, quite common in a somewhat limited sense! Model jet turbines with impressive performance are readily available although the costs are (at least to this penny pinching engineer) pretty high (somewhere in the $2,000 and up range) and there are a number of model airplanes available to house these engines.
The newer ones are incorporating an impressive amount of 'smarts' (i.e. uP controllers) for much greater ease in starting and running. The engines are also incorporating trust control including vectored thrust control (i.e. the engine's output can be slewed from the normal axis to permit some amazing variations in the aircraft's flight path).
The performance of these jet equipped models is truly impressive .... and loud!
Unbelievably stupid; When an overspeed sends 2 halves of a centrifugal compressor in opposite directions, you can get two students at once. Then, the unloaded turbine can overspeed and blow. A tour of a real test cell with pictures of the torn up concrete walls looking like machine gun pits and ripped up casings should be coming from the professors. Even the brilliant designers and builders at Pratt, Rolls or GE keep concrete or 20 pains of glass between themselves and the new product........
I think that the term, "stupid" is a little harsh. People place way-too-much emphasis on safety to the point that it impedes R & D efforts. True, the students, and faculty need to take precautions, but if we buy-into your philosophy, we wouldn't have had a great run with the Space Shuttle. We lost two ( 2 ) crews, but while tragic to be certain, you didn't see anyone back-away from future missions, either. Life's dangerous, period, and end, and we're all going to, "buy the farm" sooner, or later. I'm not seeing a down-side to dying while doing something that you're passionate about - it sure-as-Hell beats dying while taking a dump in the Nursing Home restroom.
I think you have just perfectly illustrated Martin's point. Even with all the testing and safe practices utilized on the space program accidents still happened and lives were lost. To assume those were the only lives that would have been lost if all of the precautions had not been attended to is just plain wrongheaded. Why do you think the missions were suspended after each of those tragdies? Studies were conducted and changes made so those would be one time occurances.
As for as your "We are all going to buy the farm" attitude: I hope you have the decency to tell all of your coworkers of your feelings before you engage them in any activity that could be hazardous. If you continue to work in that manner, you will not have to worry about that nursing home. My hope is that you do not take anyone along with you. Stupid may be a harsh word, but it will do until a better one comes along.
I don't endanger lives, nor do I think that safety is something that should not be taken seriously. My co-workers' safety always supersedes mine.At the same time, the Shuttle missions suspended notwithstanding, it's obvious that you would have ended the Shuttle program, based upon your response. Attitudes, such as the one you illustrate would have resulted in all of us eating sauerkraut, had it not been for the myriad of brave people who fought for world freedom in World War-II, unless you’re naïve enough to believe that all military equipment was fully-tested to cover all safety contingencies back then.You pick up the pieces of mistakes, learn from them, and go one - you DON'T say, "boy, this is dangerous", and stop.
That's the point that I was making. It's your right to be meek; yet, it's also my right to embrace challenges.
Nick, The first wheel was used perhaps 3000 years ago. Major improvements only began 100 years ago. The Chinese had crude rokets 1000 years ago, but when Goddard did his pioneering work, with no gov help, he was ignored by all but the Germans. During WWII we became good at building aircraft, but few were state of the art. In 1957 I was a student at MIT & that year we got 'a kick in the arse' when we heard the 'beeps' from Sputnick I. We has a 'peaceful' satelite program, the Vangard, that was built by a naive Naval research center. The first two exploded on launch. Von Braun & his German team had tested V2's in New Mexico & were then in Huntsville developing short & medium range rockets. I know from those on the scene where Von Braun had his team 'working on the side' to develop a satelite via existing military-based launch vehicles. After the Vangard failure Von Braun said, 'I'll launch one in 30 days' - and he did. (My small company built electronics for the Saturn V and I spent a lot of time in Huntsville).
The Russians had a great exhibit of space hardware in Ft. Worth, TX in the 1980's and I was amazed at how crude some of their hardware was. Only after the breakup of the USSR did we know how many failures and losses of life that they had. And remember, that was 'the cold war'. In WW2 the atomic bomb was developed in just over 3 years. It took a team of scientists & engineers from all over the world to convince a mostly-ludite gov to proceed with a weapon that saved 1,000,000 American & Japanese lives AND held the USSR at bay until their economic collapse. (See 'The Making of the Atomic Bomb' by Richard Rhodes). Were there deaths during that development?. Yes, but the risk-result worth it? I think so.
The 'nanny state' tells us what to do. Are they qualified? NO !! DOE spends more on solar & wind than on advanced nuclear. We have more oil & gas than Saudi Arabia - more than 100 years worth - and we find more every year. Do you want 2 mil high-paying jobs? Ships exporting petrol products rather than importing them? Super-clean power generation, CNG for public transport, school busses, and passenger busses? LNG & petrol ships for exporting OUR products? You need only to look right here in the USA and Canada. I KNOW THE PETRO-CHEMICAL, PIPELINE, AND SHIPBUILD INDUSTRIES WELL.
(I would love to have my 1955 Triumph TR-2 or my 1964 Corvair. But,alas, we are no longer able to buy cars like those,)
I am glad to see you have rethought your position. The opposite of wreckless is not meek, but the opposite of cavelier is thoughtful. Your cavelier attitude toward the safety of coworkers that was presented in your first post has been replaced by a more thoughtful response. I just hope the attitude shift was real and not contrived when you realized how silly the first post sounded.
A couple years back when I had some downtime between jobs my friend Asim and I built a nifty jet engine using a turbocharger. The interesting part was constructing the combustion chamber. I designed it and created the CAD drawings and had a local machinist cut the metal from scraps I got at a boeing scrap yard in Kent WA. teh compbustion chamber was about 20 inches long and made of some Inconel pipe I found.
It worked well enough but it turns out to create any kind of useful thrust the engine has to move a lot of air. The turbochargers from cars and big trucks have very heavy casings to resist catastrophic failures so I was not too worried about the high speed compressor rotor coming apart.
The idea we were working on was to create a Solar powered engine to drive a PMG directly coupled to the turbine. Unfortunately I had to go back to work but it was certainly a fun project. I wish I had the pictures and the thermal analysis software I wrote for it.
Hey Ivan... I was hoping that someone who built one of these 'turbo-jets' would post. I've watched a few hours worth of the videos that the backyard mechanics have of these up on YouTube... They look like a fun toy to experiment with.
And going with an old auto turbocharger seems relatively safe.
Back in 1967 I was involved in a project with some friends who were attempting to build a pulsejet engine to drive a bicycle "a bit faster". WE did succeed in creating a device that gave us lots of heat and noise, but no worthwhile thrust. Of course, that was closely related to our not having access to any machining capabilities.
But it was quite educational. Did you know that at 500 degrees kerosene will explode just like gasoline? In addition, when it is that hot it does not require any special nozzle to create a mist in the combustion chamber.
The pity is that if we had been able to come up with a good set of reed valves the thing would have been very impressive indeed. But I can't imagine sitting in traffic right near a jet engine that was glowing a dull red. We certainly would have understood dealing with waste heat, and probably some other things as well.
Although we did have some "incidents", we never had any burns or other injuries.
As an electrical engineer, my peers raise their eyebrows when they learn of my interest in jet engines. I love reading about, and sometimes experimenting with, turbines and pulse jets, and an occasional rocket (OK, so it's not an air-breathing jet engine).
I enjoyed the construction article and I'd like to add to the commentaries an experience I had with a pulse jet and the useful lessons I learned. Please see the following link in Design News magazine:
I remember so long ago reading in Popular Mechanics how a backyard mechanic built a tiny jet for his glider so he wouldn't have to use a tow plane - and apparently it worked! So as a kid I read through all the jet engine articles in the encyclopedia and everything they had at the library.
Jets deliver decent fuel economy and incredible power density but they are the opposite of "tractable" in that they don't really make a lot of (low speed) torque and they don't handle changes in power output very well. However, I always figured a small jet running an appropriately geared generator would make an admirable hybrid powerplant for a car.
Then again diesel-electric locomotives were the original hybrid, and I've never heard of a jet-electric locomotive, so maybe it isn't such a good combo in reality.
Interesting - according to whoever contributed to Wikipedia, the "micro turbine" is recognized as a promising technology for powering future hybrid electric vehicles. Efficiency of modern versions approaches that of reciprocating engines. Hotter exhaust is also more useful for cabin heating/cooling. Range Rover is apparently currently working on another turbine powered car (a turbine electric hybrid) as a follow up to their failed 1960 Rover turbine prototype that, lacking an electric intermediary stage, had terrible throttle response. So interesting! Wow, maybe batman was right after all, maybe jet cars will finally become reality. If the turbine has just 1 moving part like the electric intermediary, maintenance should really be a thing of the past.
I don't know how viable a turbine would be for a car. Look at the Abrams tank, which needs 7 gallons of jet fuel just to light the engine. It's got a 500 gallon tank but I believe Abrams tanks in battle need a hefty supply line to support them, because they have to be refueled every four hours.
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