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GE and NASA to Revive Open Rotor Jet Engines

Back in the mid 1980s, GE and NASA began testing on a new propulsion system that used counter rotating fan assemblies in an attempt to boost efficiency. The testing ultimately led to the design of the GE36 experimental aircraft engine, but was then set aside to explore other options. Now, GE and NASA are planning on revisiting the design and adding some new technology to the mix.

GE36 Demonstration EngineGE36 Demonstration Engine The design is ultimately a hybrid between a Turbofan and Turboprop, which was aptly named a Propfan or Unducted Fan. The process begins by using a turbofan engine with the fans relocated to the outside of the engine housing. As the exhaust from the turbofan engine is forced out, they pass over a turbine which is connected to a prop on the exterior, while the other prop is driven by the turbofan.

Both sets of props have variable pitch blades that featured a dramatic curve, similar to a scimitar, which would allow the engine to reach speeds close to Mach .75. Along with the high flight speeds, the engine also showed a 30% to 35% decrease in fuel consumption. The only real drawback to using a Propfan engine was the noise that was present inside the cabin.  This, when combined with a shifting market, ultimately led to the design being shelved.

Skip to today's market, where the price of fuel is driving everyone in the transportation business to find ways to increase efficiency and decrease consumption, and the Propfan engine could change the air transportation industry as we know it.

Refurbished Testing AssemblyRefurbished Testing Assembly GE and NASA are planning on performing tests throughout the summer and into next year, using the same rig they had employed for testing on the GE36. They hope the advances in wind tunnel diagnostics and aerodynamic modeling will be able to offer a better picture of the feasibility of the experimental engine.

The testing itself will be conducted at the Glenn Research Center in Ohio and will focus more on the blade design rather than the engine itself. They plan on testing 6 different styles of blades, each with different lengths and sweeps, and determine which is able to provide the best performance for its intended application.

Assuming the tests are successful, it might not be very long until we start to see open rotor engines on commercial aircraft. Aside from decreasing costs for the airline, a 30% reduction in fuel usage would have a huge impact on the prices of airline tickets as well as the amount of emissions being released into our atmosphere.

Green Car Congress

George Delozier
Motorized Innovations
InventorSpot.com

Comments
Jul 8, 2009
by Anonymous

Other Apps

USCG aircraft
Exec VIP aircraft
Cheap version of "AF1".
Pvt Planes
Air Cargo lines.
Test planes
Copters.

If it improves speed & saves Fuel, then YES, Mass produce this.
IF for DC9 types?
737 types?
OR reuse 727 types?

Be neat for Obama to use in a 777 (cheap AF1) for short range use jet.
Or other CEOs.

Jul 9, 2009
by Anonymous

Rock On People!

Innovation will be the key to maintaining growth and progress in the human experience....looks to me like Jobs, Jobs, Jobs!!!!

Dallas Taylor
MN

Jul 9, 2009
by Anonymous

Detached Blade?

And if a fan blade detaches and penetrates the cabin (killing n people in the process?)...

Jul 9, 2009
by Anonymous

That same thing that happens

That same thing that happens when a prop detaches from a regular turbo prop *eyeroll*

Jul 9, 2009
by Anonymous

Noisy

This won't work, the trend is to quieter jet engines, and I'm no engineer, but I guarantee this would increase noise.

Jul 9, 2009
by Anonymous

Oil Kills Planes

As the price of oil goes up, travel will change! We now have passenger and freight dirigibles on the drawing-boards, and in proto-types! Rail, once the "King of Travel" will come back in a modern fast, efficient form, 400% more efficient than trucks for freight anyway, has a distinct advantage! Lifestyle changes - away from the extravaganza of the 20th Century "American Dream" and flying whimsies, to a more computer conference, email based, world is here now with Skype and the like! The need to move human bodies long distances fast is being diminished by teleconferencing, and shrewd business practices, and the folly of the 20th Century, great planes to rush about with great personal importance and egoism, is now becoming part of a much hated "Rat-Race", cause of cancers, hypertensions, obesity, high blood pressure, lack of exercise, frustrations, and bad health in general, and to be avoided by sane human beings at all cost! It is no longer a sign of status if your company flies you somewhere, it is a badge of indenture, a "Black" mark on you, and a negative thing! We move into a low-impact, highly educated, less greed driven 21st Century, and in competition with the Asians, who by nature are adverse to the American 20th Century practices of waste and extravagance, and eat primarily in vegan fashion and in modest amounts - a shock for sure to the gluttonous American carnivores we send abroad, expecting free meat-feasts, A La Americane, in countries where a cup of rice is considered plenty! The 'plane is dead, and the daily flights at home will diminish to keep us competitive with the larger, Asian portion of the world population! We can hardly sell our products competitively priced and partake in the extravagance of daily airplane rides to produce them, can we now - not when the competition is so frugal and cost-conscious!

Jul 9, 2009
by Anonymous

Noise reduction

Using this type of engine on a rear engined aircraft such as an MD 90 may help with the interior noise problem.

Jul 9, 2009
by Anonymous

like Tu-95?

like Tu-95?

Jul 9, 2009
by Anonymous

profits...

Looks exciting, but the 30% reduction in fuel usage would most likely have a greater impact on the airline's profit margins than the price to the ticketed passenger.

Jul 9, 2009
by Anonymous

Don't panic

I am an Aeronautical Engineer at Loughborough University. the trend that airlines looking for is reduced fuel costs, that why aircraft are being designed to be made from composite materials, eg the 787. Light aircraft means less thrust required to produce lift. The open rotor design produces high amounts of thrust while using very little fuel.
If you looked at turboprops 20 years ago, they are no way near as efficient as turboporops of today. Turboprops are actually more efficient than the turbofans that power most of the worlds aircraft, which is why airlines are trying to introduce either conventional turboprop or open rotor turboprops.
The only reason the airlines don't is because of passenger worries. The mindset is, if i don't see it moving its not there. It will come to the point where airlines will ignore this and go ahead anyway.
If you are worried about a blade flying off, then think about the number of unrestored airworthy WW2 aircraft that still have their original propellors.....

And no its not like a tu-95, that uses contra-rotating propellors and is still a turbojet.

Jul 9, 2009
by Anonymous

Sound Levels

Part of the blade-shape testing is determining what the relative trade-offs are between efficiency and noise levels.

Jul 9, 2009
by Anonymous

Yes and No

As someone who travels for a living, my travel is not heavily influenced by telepresence technologies. Many customers (gov't and DoD (natch), banks and medical firms) have security standards that preclude the use of remote services. Given that expertise is not equally disbursed on a geographic basis, an you still have a requirement for people to travel.

Jul 9, 2009
by Anonymous

Scale and durability

How does the overall size of these engines compare to current engines with the same thrust? Can they be slung under a wing? If hanging under a wing is possible, how is the durability compared to current engines when brushed or bumped by a ground vehicle or tool wielding ground crew?

Jul 9, 2009
by Anonymous

Lots of other problems

Some problems with open rotors:

- Safety: There are no regulations for this type of engine. Blade containment is a real issue. Moving the engine to the back of the plane and away from the fuselage requires new structural foundations. No safety regulations are even written for this type of configuration.

- Installation: There is no infrastructure nor processes in place to install, maintain and operate engines of this type. It's not going to be easy. Today, most engines are under wing. Now they will be over the tail. Will we need new lifts in hangars? Or completely new hangars?

- Noise: This is a big deal. In early prototypes, the noise was so bad that it wore off the paint on the plane. The buzz inside the plane caused people to get sick. The noise outside the plane would eliminate service to many airports. Don't dismiss this. It's a real issue.

Also, alternatives are emerging. Check out Pratt & Whitney's Geared Turbofan technology.

Jul 10, 2009
by Anonymous

consumers eat it

aside from the technical aspects. If this did save airlines money, they wouldn't pass it onto consumers. More likely they'd increase the price of the tickets, ha.

Jul 11, 2009
by Anonymous

@Oil Kills Planes.

What year do you run for president. I wish I could meet more level-headed people like you. I bet you have heard of the Venus Project and the Zeitgeist Movement. If you have not, Google them. You basically said everything that runs through my mind constantly. Stuff like: Why are we American's so greedy? Why do we waste so much? I just don't get it and neither does half of the world or more.

Jul 12, 2009
by Anonymous

the same thing that would

the same thing that would happen if a prop detached on one of the thousands of turbo prop planes flying everyday.

Jul 17, 2009
by Anonymous

the same thing would

the same thing that would happen if a fan disk in a regular jet detached and has detached (cant think of the name of the flight but its infamous it cut all three hydraulic lines)

Jul 17, 2009
by Anonymous

Tail mounted configuration isn't new

Several commercial aircraft have already employed tail-mounted engines, including the DC-9, MD-80, MD-90, and MD-95, and some are still in service, so I'd assume there would have to be some kind of processes and procedures in place for maintaining these. The only real big difference, I think, is the external fans.

Jul 24, 2009
by Anonymous

this is how progress is made

I saw this engine flying the first time they tried it, it is a bit noisy but that can be worked on. Blade containment is no more an issue with this engine than with any large , high bypass turbofan flying today. Speed increase will be minimal. The main benefit to this design is fuel efficiency, anytime you can get the same power for less fuel you are doing better. My opinion is that designs like this will cause a new design philosophy in the aircraft industry to gain a little stronger foothold due to the need to operate quietly and more efficiently than is possible today. Boeing is still designing aircraft that are eerily similar to the 707 because it is cheap, easy and there is no real alternative available. That will have to change if this engine is successfully developed and marketed. A good idea that needs a little work requires innovation, this is how progress is made.

Aug 29, 2009
by Anonymous

this should be fitted on the

this should be fitted on the new jets like the A380 for greater lift and efficiency...well seriously it's a great concept and i just got to knw it now when i saw this.
-www.astroaviator.com