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Gadget Freak Jr.: Homebrew Jet Engines

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Beth Stackpole
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Blogger
Ingenuity at work
Beth Stackpole   10/27/2011 7:38:22 AM
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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.

ChrisP
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Silver
Re: Ingenuity at work
ChrisP   10/28/2011 12:11:50 PM
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Could somebody please explain what "innovation" is present here?  Did somebody design a better engine?

 

I think this is actually called reinventing the wheel.

BobGroh
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Platinum
RE: Homebrew jet engines
BobGroh   10/27/2011 11:01:15 AM
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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!

Martin
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Bronze
Test-stand turbo
Martin   10/27/2011 3:26:54 PM
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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........

Nick
User Rank
Iron
Re: Test-stand turbo
Nick   10/28/2011 11:50:51 AM
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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.

Tool_maker
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Platinum
Re: Test-stand turbo
Tool_maker   10/28/2011 3:08:56 PM
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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.

Nick
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Iron
Re: Test-stand turbo
Nick   10/28/2011 8:42:09 PM
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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.

 

Bringier
User Rank
Bronze
Re: Test-stand turbo
Bringier   10/29/2011 3:33:53 PM
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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,)

Bringier

Tool_maker
User Rank
Platinum
Re: Test-stand turbo
Tool_maker   10/31/2011 6:38:49 AM
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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.

Ivan Kirkpatrick
User Rank
Platinum
Turbocharger as Jet Engine
Ivan Kirkpatrick   10/27/2011 4:36:01 PM
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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.

Ralphy Boy
User Rank
Platinum
Re: Turbocharger as Jet Engine
Ralphy Boy   10/31/2011 5:00:07 PM
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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.

 

William K.
User Rank
Platinum
Homebrew jet engines
William K.   10/28/2011 8:51:48 PM
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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.

MYRONB
User Rank
Gold
Homebrew Jet Engines
MYRONB   11/28/2011 5:05:50 PM
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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:

http://www.designnews.com/author.asp?section_id=1386&doc_id=218951

Best regards,

Myron Boyajian

 

Grunchy
User Rank
Silver
Re: Homebrew Jet Engines
Grunchy   12/2/2011 10:49:13 AM
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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.

Check that - 11,100 hp turbine-electric locomotive was successfully tested in Russia Sept 2011, pulled 16,000 tonnes.

ricardo
User Rank
Silver
Re: Homebrew Jet Engines
ricardo   12/2/2011 4:47:24 PM
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Actually jet engines have terrible fuel consumption.  As do turbine powered shafts as in turbine powered cars.  Their big advantage is power/weight.

It's only very recently that high bypass turbofans on airliners became comparable to other engines on a distance/payload/fuel basis.  And this requires operation at very high speeds & altitudes.

There was a rash of demonstration turbine cars in the 60's but then came the oil crisis ...

Grunchy
User Rank
Silver
Micro Turbine (turbo alternator)
Grunchy   12/2/2011 9:52:14 PM
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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.

Alexander Wolfe
User Rank
Blogger
Re: Micro Turbine (turbo alternator)
Alexander Wolfe   12/4/2011 6:20:32 PM
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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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