Jet Engines

[concernedsophist]

Would it be possible to make a jet engine that is substantially smaller than is currently used? I?m thinking of something the size of a model airplane or model rocket? It seems like such a small engine would be useful in unmanned aircraft.

 

[eLiu]

here

My thermodynamics professor works on these "micro-engines". They're Brayton cycle driven jet egines that literally fit in the palm of your hand.

It's really neat. The technology isn't mature though. Efficiencies are too low and they're having a lot of difficulty closing the cycle...but it's getting there.

 

[concernedsophist]

Thanks. It sounds pretty neat. Does it use conventional metals, or some high tech alloys or composites? Does it need a special type of fuel?

 

[PowerEngineer]

Google is your friend...

 

[eLiu]

picture in here

This was an old homework...but it has a picture of the engine. Look at how small that sucker is. The size of a freakin stamp.

There's some info about the engine in that problem...and some more info in the solutions S04_PS6_sol.pdf. e.g. it runs on kerosene

 

[concernedsophist]

eLiu, last link is inop.

 

[Fallen Kell]

There were some videos on the net about a bunch of B52 fanatics who built working models using "micro jets". They were fully working remote controled jet model airplanes. The biggest problem they would run into is when the plane got out of range of the transmitter...

 

[pm]

One of the more recent issues of MAKE magazine (a magazine for building geek stuff), had a home-made "jet" engine made from a preserves jar and some tin foil and wire.
http://www.makezine.com/05/jamjarjet/

For more serious model jets, there's always the RC Groups model jet (fuel) forum:
http://www.rcgroups.com/forums/forumdisplay.php?f=34

Since only the hardcore guys mess with micro jet engines, if you want more activity and a lot more interesting models, there's always the RC Groups model jet (electric fan) forum:
http://www.rcgroups.com/forums/forumdisplay.php?f=12

Electric ducted fans are a lot cheaper and easier than real jet engines, and the models look good and fly realistically.

 

[everman]

They already exist all the way down to being measured in microns.

 

[eLiu]

Originally posted by: concernedsophist
eLiu, last link is inop.

Fixed it.

 

[lyssword]

wasn't Jay Leno was riding a jet-engined motorcycle? I've seen it somewhere...

 

[WildHorse]

Don't know how small, but as just an exercise in imagination:

it seems likely a nano machine could pump liquid or gas through a nanotube creating a jet. Maybe the pump could be powered by chemical reactions with the medium it's submerged in, or perhaps from bioelectric energy, such as is created when neurons fire.

Could be invisibly tiny enough to sit in the alveoli to aid respiration in people suffering breating problems, jetting oxygen into the bloodstream and Co2 out. Or maybe floating inside your blood vessels to do something or other.

 

[DrPizza]

I recall a video (a link to it was posted here) that showed a model B-52 with very small jet engines.

There was also another video where a skydiver had one of those suits that helped in glide for a while, and he attached jet engines to his lower legs; he maintained a level flight for quite a distance.

 

[benlewis]

And what about cars? When I was a kid (a long time ago) Chrysler made a turbine driven car. It was a test car, but as I recall they made several

 

[gsellis]

There are also videos of an F14 Tomcat RC that uses the same jet engines from the company in Germany.

BTW, the B52 was crashed a few months after the first flight. It has the same issue that the original does with banked turns. Too much banking and it falls out of the sky. It did and the got the smoke cloud on video.