A Naked Engine For Cleaner Flights

If the blades can rotate, that probably means they are on a small(ish) diameter pin that connects the blades. If that is the case, it isn't hard to imagine one of them fatiguing and breaking over time and sending a blade straight into the side of the plane. This would make for terrible news in the aviation industry.

Engineers have been using rotating blades for decades now though ToomeyND. Im sure that they can calculate the correct material and diameter to use for the pin with the design software they got these days. Still this would seem as an exceptionally high risk yes :P

That said, they look very very cool though :P Would love me a naked jetpack :P

Just because engineers can design a strong blade, doesn't mean that stress over time, manufacturing defect or maintenance problems won't lead the blades to disconnect and cut the plane in half. A bunch of F-15s were grounded due to a manufacturing defect which shortened their life to half. And a few airlines were just fined a a hefty sum for not properly maintaining their planes.

Obviously, there are problems with traditional jet engines too, but I don't think this is the trend people are going to go towards. At least, not in the USA. People are trying to eliminate petroleum products from the airlines altogether.

Besides that, until they make it as quiet (relatively) as conventional jet engines, noise pollution would be a significant factor as well. Planes already make too much noise for most people and having a bunch of these flying over NYC driving New Yorkers bonkers (more than they already are) would be catastrophic. Those people are already crazy, no need to drive them any more insane!

rpenri,

To your noise pollution point, if there is a 26% reduction in fuel, aka the efficiency has increased, wouldn't that mean that more of the energy from a gallon of fuel is being used as thrust, and therefore produces LESS noise? This logic might be terribly simplistic, but it makes sense in my small head.

ToomeyND: maybe, but i think the external casing probably provides a fair degree of insulation/sound dampening.

Degeezee is right about that one, but rpenri also has very valid points. Stress over time is a huge factor in airline safety, and we do need to move away from oil. On a related note, do you guys think we'll see an increase in shredded poultry for sale? I mean it looks like they just invented some pretty innovative 'processing equipment'.

@ Toomey ND
The current jet engines can do that with the shell around them. It is called a shell out. Ask any crew chief out there they will tell you there are places in a plane it is better not to be.
O when this happens it is called a shell out. O and I am that crew chief you could ask... yep I say they can shell out just like they are that is why we have paint stripes on the planes that tell us where not to stand when we work on them.

lol @ thatotherguy for the frozen chicken test remark. I forgot about that testing method.
As to fatigue. Yes the parts in the engines fatigue. That is why we inspect them after every flight and do in depth inspections every so many hours of flight.
As to the f-15 remark for them being grounded... that is my aircraft body that I crew chief. The generalization that you made is partially correct soem f-15's were grounded for that. The thing not mentioned in that is that the aircraft has served so well that the military has decided to fly some of the aircraft as much as 10-30 thousand hours past there retirement age. Planes like cars have an odometer of sorts. However this odometer is done in hours not miles. If I recall correctly the f-15 is supposed to be retired at 6000 hours or 9000 hours roughly. From the government stand point the plane costs 68 billion dollars a piece so they tend to want to fly them past retirement age. by lots of hours. On the other note they have been phasing out the models that happened to crash. You have to bear in mind that there are many models and versions of the plane the most capable version and most recent version is the US model f-15E which coincidentally does not share that structural weakness around the forward module.
The best part of the f-15E is that it is what all other planes are judged against. The planes original design is around 40 years old or more. So when I see the English saying that they developed a plane that can out match the f-15 it makes me laugh because of the f-15's age. Also knowing that it was not publicly released right away means that you probably can't fathom the technology that is being kept secret.
Another side note to point out the age of aircraft equipment. The anti lock brakes that are on your car were old old news when they were finally introduced and have been on f-15's since the beginning as well as other aircraft. coincidentally the story on popsci about gm's new heads up display windshield as we all know is really really old. Those things have been in aircraft for a long time. Many people didn't notice it but the under panels on some luxury cars tat have golf ball divots not only came from golf balls but the tiny holes around engine intakes that smooth airflow over the metals surface.
Really it isn't to likely to get away from fossil fuels in planes until the fuel runs out. For mass transit and military purpose it isn't close to feasible. To give you an idea it takes about 12k pounds of fuel per hour without afterburners on. When you compare that to the larger planes that carry people that are much heavier you can imagine the fuel consumption in those aircraft. So far the only alternative power plane that I have read about seams to crash at random it is run on batteries though and can carry 1 or 2 people. My guess is that pound for pound the cost of transferring electricity through power lines to whatever remote location is charging the batteries of this aircraft is about the same or worse than the current usage do to counter electromotive force loss in power lines. another thing to consider is that like oxygen scrubbers getting an exact out of power indicator on batteries is iffy at best. So that means you may fall out of the sky because the battery showed full charge on take of but some hidden battery damage made it so the charge depleted 15 minutes after take off instead of 90 minutes after take off. With that said I will stick to fuel. Also you may want to consider the strip mining being done to make those battery cells.
From what I see we aren't really improving anything we are just making it so we can pay more for less. But what do I know I am only a crew chief with fuel, aerodynamic, hydraulic, and electrical expertise in the form of real world practice rather than commercialized panic. But, who am I to argue with you those hard to charge explosive batteries filled with rare minerals and toxins are way better than the current plan.

A. by 2020, we'll probably have better ideas than this, b. why would it take them, after already having developed it, 37 years to implement? Seems like a waste of time, and a huge waste of fuel.

finaly, i have seen this type before in Russin planes. The artical is right on why this was never was succesful in the first place. I think that this engine is the future of aviation.

in reference to a few comments posted above: what if they were to place a gyroscopic type ring (around the blades) that lets the blades run freely (Same principle as sprewell auto rims)for added "protection" Angled properly,this could possibly divert the air leaving the blades through its circumference, making it thrust back. which in turn less air pressure changes around the blade,less sound?, more rear thrust, better fuel economy? am i on the right track of would a ring throw off the whole concept of "naked engine?

@ToomeyND: Well, I don't know if mechanical failure of the blades poses an especially serious danger. Propellers have been used for ages, and I assume the risk for mechanical failure for them is about the same.

Nothing lasts forever, and that's why it's essential to inspect and calibrate the hardware every now and then. This is true for everything, not only the aviation industry. Bad luck doesn't just happen, it is caused by bad maintenance.

@gonzoj89: You are sure that you want to use the Mensa logo as your profile picture?

Alot of the sound is from the counter rotating blades. For example. When you hear a helicopter what your hearing is the sound of the air coming off the main rotor and hitting then tail blades. That is why it has a rhythmic woop woop woop sound. We have actually made a pretty stealthy helicopter called the "commanche" the tail rotor is angled and has a cowling to prevent this from happening. Just imagine being the bad guy and a almost silent heli comes out of nowhere to ruin your life.

Twopath - The cost of the F15 - you meant to say million, not billions of dollars. Actually, the original F15s back in 1972 cost $42 million per year.

So twobrain, what are the options for the sustainable aircraft engine of the future?

Well of course it spins, its basically like a Turbofan engine, big blades in the front small blades in the back... but its "naked". It's like a propeller which is more efficient than a jet engine in slow applications... in a sense where it covers more area and at slow speeds it is very efficient.(Plus propellers like helicopter rotors have a limit at speed) Jet engines however are better at speed, ceiling as well. Once it's going just feed it fuel.

This reminds me of the ThunderScreech XF-88 I think... supersonic propellers extremely loud like EXTREMELY sonic booms etc...

I wonder if because of this (the whole naked thing) the jet will fly slower (more drag) and the bigger blades=slower spin

Scramjets are the way to go! Haha talk about fuel consumption

reddwhite I'd like to comment on your comment haha... what about the fact that "rotors create wakes which one rotor hits the other rotor's wake thus creating the sound". (This was from a previous pop sci post on new silent rotor blades)

Go coanda effect! No tail rotors :)

Ahh its xf-84 haha I was 4 off

This all sounds great but.... an enclosed fan is designed to keep the parts inside when a catastrophic failure occurs.. and they will.

With these blades spinning at mind numbing speeds, i would be hope they would put them in a place where if the blade would detach, it would not rip through a passenger compartment OR damage vital components (hydaulic lines, fly by wire controls... )

Seems a bit to hap-hazard for my taste.. Increased economy at the expense of safety..

@Dustin2127.
I'm sure you have heard once or twice the time it takes for the FDA to put a already-engineered drug into the market right? ~10-15 years.

It takes that and sometimes longer to put design and put a new military technology into the mainstream. I wouldn't be surprised at somethings even taking 30-40 years if the requests for proposal got denied a few times. That and with each new presidential administration, some projects get canceled and renewed again every 4-8 years. Other things that can delay new technologies is that most countries or whoever is funding the corporations doesn't want 'new' which often have bugs, they want the tried and true old tech.

i don't care how loud and dangerous it is, i want one in my computer!

Few things readdressed:

Price: With American not foreign mods on the E model which is the only model not already set to have been retired... I believe they are set for a 2020 retirement if I recall correctly. However you are correct on million not billion but the digits stay the same the E model we use costs a little over 68 million with our package... our plane (as in American)Our defense package... not available in other countries. I model J model etc. I do believe even the e model is past its time though they purchased the last 15 f-15E's only a few years back. And credit to the comment that remarked on the tried and true. You are correct they like tried and true but they love new toys too. Credit to that is the new model planes were carved up for parts instead of flown last I heard.

Green flight: Sustainable energy with current tech isn't really achievable with the demand of use that we have for planes, but additional charges and strip mining for current tech are available... you moved energy consumption not removed. Don't forget the pollutants added by the large strip mining machines adding to the "carbon footprint" of "green" vehicles...
Shell out: The can liner is round about 1/8th inch thick titanium alloy. The blades (spinning at if I recall correctly 9,000-13,000) are made of nickel and I don't know the weight but they aren't exactly light so yes the kinetic energy of those blades when they shell out will easily pierce the shell and hull of the craft. As I said though they are the core of the aircraft so inspection on them is heavy. Think of how straws of hay fly through barns in a tornado trust me a blade of nickel will fly right through a plane... again this goes back to we have places we are not supposed to stand around aircraft. At least for those of us working on military units. The use of the shell is basically part of the air concentration that is required for turbojet/shaft jet engines. I don't recall the compression required at each fan stage though.

This particular design would definitely not work for a fighter application for radar issues alone, but it would work just fine for replacement of turbofan jet engine types. Three types of traditional jet engines exist Turbofan, Turboprop, and turbojet/shaft. note this list doesn't include ramjet because that is a completely different principle of powerplant application. The design shown here may also work for turboprop but it may create issues with the prop portion of that motor creating turbulence in front of the actual drive blades. I would bet the turboprop would not do so well either. The reason I think it wouldn't work so well for turbofan style engines such as those found in fighter aircraft is that basically try to make a wind funnel that is very smooth flowing so that they can control airflow through the afterburners otherwise they would light out.

The only answer I have ever heard of for sustainable energy is still only a myth. That method is cold fusion. Lets face facts though until we are out there will be no real pursuit of true sustainable. Why because you can't make a profit on something that works that well. At least not to the abusive levels that we are paying now with the energy trading that is going on.

^ I agree.
Even if sustainable energy or free energy existed, it would never be any cheaper then what we pay now. Even if it was cheaper, we would use more of it and still pay the same.

The only thing cold fusion would solve is our (and by our I mean businesses') limited resource problem, it won't solve anything else people want out of it.

Maybe with the exception of self sustaining households, and then by the time this is mainstream I'm guessing there will be a tax or a premium on it, or some part that needs to be exchanged only by the manufacturing company every so often.

Off topic and as an example to my last note: Oakley watches with batteries can only be serviced (batt replacement every ~2 years) in California or Switz. It's free, but the shipping you pay is not very cheap especially if you live out of country.

Why couldn't they use a retracing shell. Have it closed up at least partially on the ground for noise and safety sake and then after take off retract it along with the landing gear. I would suspect that even if its only 70% open due to the retracted shell it would still provide a decent increase in efficiency. Sure more moving parts translates to more PM and more chance for failure but if it gets jammed then so what? You’re losing efficiency not something too vital. Unless, they were counting on the increased efficiency and loaded less fuel to the point it couldn’t make the trip with the shell on. This is all speculation though.

Hmmm.. the folks at GE must be a bit daft..?? Chasing technology that all the post(ers) here feel is unworkable. Speaking of blades detaching in high bypass turbofans, anybody have data on how often this happens..?? I've been 'close' to the airline industry for over 40 years and I've never heard of it happening (except in tests). How about turbo-props..?? Anyone got data on how often THEY 'lose a blade'..?? Everybody keeps yakking about fatigue, etc... places not to sit on airplanes,and catastrophes for the airlines etc, and 'watch out for exploding engines'... so, how many lives lost by exploding engines on airliners..?? Compare this to 400,000+ lives lost in car accidents per year in the USA... I would wager that ALL the lives lost IN aircraft including all wars, don't add up to one year of car deaths.

Then, we get the "move the air travel business away from fossil fuels"... this one I like..!! It's WAY out there... I've lost the links to sites discussing the cheapest way to produce a calorie of heat (energy) but fossil fuel is still WAY, WAY cheaper than anything else. While I'm a fan of electric RC airplanes, I don't see commercial aviation going electric anytime soon.

Fortunately, GE employs good engineers and statisticians. Will someone be killed someday by a broken propeller blade from one of these new jets..?? Maybe.. Will it be big news if it happens..?? Absolutely. Will it be 1,000 times safer to fly in a jet of this type than drive to the airport in your car..?? Certainly.

The F-15..?? Awesome piece of technology..!! Amazingly, some very early airplanes (WWI era) that are VERY dangerous to fly, are still flying and not killing anyone. Props are not flying off, wings are not fatiguing and falling apart, and pilots are not flying them into the ground and dying.

Next topic..?? Toyota accelerator issue..!!!! With millions upon millions of cars produced, 50 to 100 cases of runaway that can't be 'explained'. Yep, let's consider ALL Toyota's unsafe..!!!! Can't be driver error..!!!

Big-ups to twobrain for your great comments and responses. If only the rest of the internet could be so informative and free of flames.

Regarding fan failure - brings back memories of my materials class - where we discussed turbo fan blades: They are often made of single metallic crystals, to make the structures particularly resistant to stress fractures and crack growth.

Another interesting tidbit from the same class - pressure vessels are often made quite thin. Because each material has specific crack propagation (growth) properties.
If the material is not thick enough for a crack to spread naturally, an overstressed vessel will merely become a pinhole and a leak, without being able to crack right open (catastrophic failure).

Has anyone read the article about the "quiet" helicopter blades? That's what they're talking about when re-designing the blades. Also, it makes them more aerodynamic and efficient. There is also a way to design the blade hub to where the blades could not come off in an outward motion. Easy fix. The engines could also be placed towards the rear of the airplane for an added measure of safety. I agree with you oldhat, I've been in aviation for 13 years and have never seen a blade come off of anything. Regular maintenance is the key. And, the only way you'll ever see a commercial electric airplane is when they start putting nuclear reactors in them and that would make for a big darn plane.

I don't think there would be any substantial safety concerns...I mean they still use propellers in planes. Of course these will be rotating at higher rpms, but I'm sure the engineers will make it safe. I'm more concerned how this design will slow a 737 down on landing. Current engines utilize a deflector to force air out from the front of the engine to provide thrust in the opposite direction. I can't see using a similar method for this design. Simply throwing the fans in reverse would be too stressful...like throwing your car in reverse when its still moving forward.

The safety concerns expressed in the comments here are way overblown. There is no more danger of blades flying off of this thing than with any existing turboprop or jet aircraft. Jet engine blades do come off every now and then (and engine housings are not strong enough to stop them), but these events are rare.

As for other fuels, commercially feasible airplanes that do not use fossil fuels are, at this point in time, a pipe dream.

As for reverse thrust, current turboprop airplanes create reverse thrust by adjusting the pitch of the propeller blades. It works quite well, and they could perhaps do that with this engine. You could also add a clamshell to the jet exhaust for reverse thrust.

In my view, the only real issue here is the noise. I hope they are able to solve that problem; but I am surprised that it will take GE 10 years to produce something for which it completed basic development 30 years ago.

I have personally encountered this and have heard several talks on open blade engines from people at P&W. They threw this idea around in the 1980's, GE is coming back to it now for some reason.

First, in the event of a blade throw out in the low pressure turbine on a commercial aircraft, the casing is designed to contain the blade. Blade throw outs can and do occur. In the case of this engine, a blade throw out with result in damage that is not acceptable under any circumstances. That being said, I am confident in our engineering abilities to develop proper maintenence scheduling. I have not heard of a blade out on a passenger jet.

Military aircraft are not held with the same standards as civilian aircraft. The f135 will not have to past the same battery of tests the PW4000 will have to. They are made to perform, not have 99.9999% reliability.

Second, noise is THE issue! Flight paths over major cities are changed during take off and landing due to noise constraints! Engine designers battle noise vs efficiency. In simple terms, a larger front stage will produce more thrust and operate at a higher efficiency but will be much louder.

You still run into the conflict between efficiency vs. angular velocity of the front fan and high pressure turbines with this design! The high pressure fan wants to spin very fast while the low pressure fan wants to spin slower - in terms of efficiency.

The real answer to increased efficiency is getting the low pressure turbine and high pressure turbine spinning at their most efficient angular velocities. Enter the GEARED TURBOFAN.

A couple examples of fatal "uncontained engine failures":

en.wikipedia.org/wiki/Delta_Air_Lines_Flight_1288
and
en.wikipedia.org/wiki/United_Airlines_Flight_232

My father worked as a flight instructor for UAL and was retired at the time of the Sioux City crash. He and I discussed the fact that an uncontained failure had 'caused' the crash. He explained to me how incredibly rare such failures were considering the total hours of operation of aircraft engines, airframes, and miles flown. I was unaware of Delta 1288... so, now I'm aware of two such failures in the last 40+ years of commercial jet aviation.

Certainly, there are more... yet, overall they are incredibly rare. If you think flying is tempting 'fate'... just think, the next time you're driving on an undivided highway... about the oncoming traffic. It's passing by, mere feet away, being driven by distracted non-professional drivers at 'closure' speeds that mean certain death. One small waver... a tiny mistake... well, I'd take my chances in most any airplane as an alternative.

Typically, in a turbine wheel that turns at 30 to 50k rpm inside a turbine engine the blades are not pinned into place. Instead the base of the blade is cast and machined to fit into a slot in the wheel that carries the blade. These are very tight fits and are designed so that rotational forces keep them in place. It is something to be viewed with a good deal of caution however.

I agree that these types of failures may well be rare, but a Failure Mode and Effects Analysis may reveal that the implications of an uncontained engine failure are severe enough to warrant special treatment: this Black Swan may be such a nasty bird that it cannot be ignored. For example, an engine fire may rate a 6 or a 7 because, while potentially severe, such an event may be anticipated and then managed and contained through the use of suppression systems and pilot intervention. However, an uncontained engine failure may release a great amount of energy in an instant, without warning, and with results that extend beyond the volume of the engine (damaging the wing, flight control surfaces, control systems, or even causing explosive decompression of the hull). Such a failure may rate as a 7 or higher, and, because of this, modern engine designs include ballistic protection in cowlings and/or ductwork to minimize the potential for catastrophe (...resulting from a statistically rare event). Ballistic protection may not be feasible for unducted fans.

Some more photos (I like pictures!) of "When Things Go Wrong:"
forums.jetcareers.com/general-topics/69275-american-767-uncontained-engine-failure.html
aviationpics.de/inflight/inflight.htm
pprune.org/rumours-news/301521-737-300-uncontained-engine-failure.html
flightglobal.com/articles/2007/01/29/211811/picture-ntsb-investigating-first-uncontained-engine-failure-of-ge-cf34-3b1-on-mesa-airlines.html

What do you think of "Scythe 8000" as a name for a new unducted engine model?
Help me out here: is there a difference between Ultra High Bypass and Unducted Fan engines?

Some references:
Black Swan = en.wikipedia.org/wiki/Black_swan_theory
FMEA = en.wikipedia.org/wiki/Failure_mode_and_effects_analysis

I know how!
It's simple, but in space age we still move like turtle!!!
My engine not use a fuel and everyone airplane will fly forever !!!

@ blackbay, the outside of a turbofan blade with a 5 foot radius (10 foot diameter) going at 50,000 RPM is moving at 892.5 MPH. A piece of carbon fiber going that fast is not going to be stopped by an engine casing. The fact that there is a massive airflow backwards relative to the plane itself means that if a blade did somehow break off, it would probably hit in the tail region. However, anything like that is usually designed to many times the design standard. And yes, thatohterguy, i think we will see more shredded poutlry for sale ;-)

@ blackbay, the outside of a turbofan blade with a 5 foot radius (10 foot diameter) going at 50,000 RPM is moving at 892.5 MPH. A piece of carbon fiber going that fast is not going to be stopped by an engine casing. The fact that there is a massive airflow backwards relative to the plane itself means that if a blade did somehow break off, it would probably hit in the tail region. However, anything like that is usually designed to many times the design standard. And yes, thatohterguy, i think we will see more shredded poutlry for sale ;-)

I'm looking at the picture and I'm thinking that a large portion of the noise must come from blade strikes into the vortices being shed from the tips of the turbines. The same way that helicopters do but on a much faster time frame.

1. So, what happens if the tips of the blades are joined to a "hoop" or ring? Could that contain some of the air, especially if the shape of the ring incorporated a "tiplet" shape similar to the wing tiplets that increase the efficiency of the aircraft wings by deriving some lift from the shedding vortices?
2. I know that the second set of blades will also chop into the turbulent airflow produced by the first set of blades, so how about a stationary set of "flow straightener" vanes that would effectively increase the distance between the rotating blades?
3. Will large bird strikes be more or less damaging to the blades since they are greater in length? Or will the scimitar shape just "slice 'n dice" the carcass easier?

It's very interesting because I'm told that the technology that was used when building this type of engine and rotator which actually ended up going into some fitness equipment. On http://workoutips.com/ they explain about how the rotators were later adapted and re-used.

Very interesting. I also here from time to time about hydrogen powered engines, cooled liquid hydrogen engines, and Fuel-cell powered engines in regards to saving fuel. I wonder if GE is testing these types of engines as well?

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http://newhomesteps.com/

Has anyone read the article about the "quiet" helicopter blades? That's what they're talking about when re-designing the blades. Also, it makes them more aerodynamic and efficient. There is also a way to design the blade hub to where the blades could not come off in an outward motion. Easy fix. The engines could also be placed towards the rear of the airplane for an added measure of safety. I agree with you oldhat, I've been in aviation for 13 years and have never seen a blade come off of anything. Regular maintenance is the key. And, the only way you'll ever see a commercial electric airplane is when they start putting nuclear reactors in them and that would make for a big darn plane.
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