Forum: Technology

Last edited by LordOfBunnies on Jul 27, 2005 - 07:39 AM; edited 1 time in total

This topic is based on the robustness of a lot of newer technologies that are/may enter service in the next 10 years.

Morphing Aircraft Technology - A professor here at Purdue is doing research into the field of morphing aircraft. This is not Transformers with Optimus Prime. The aircraft shape does not dramatically alter, but it does change. Examples include: change of the airfoil shape and therefore lift and drag properties, change in shapes of the rest of the aircraft, and single or reduced number of pieces in a wing because of the morphing shape. Would this be feasible in a military application?
Robust Unstable Aircraft Programming - Are inherently unstable aircraft (F-22, F-35, F-16, F-117, etc) able to take damage and still fly? Is it possible for the stability programming to "learn" what it needs to do to couteract damage or is an F-22 screwed if it takes a .22 in the wing? How robust are these programs?
Increased Lift Devices - A lady from NASA (her name escapes me) came to talk to my class. She mentioned that Boeing wanted the C-17 to be able to take off in a Kmart parking lot. Yes, 800 foot Kmart parking lot. Guess what? They made it work. What they did was have these small fans that exchange air between the top and bottom of the wing so that helped keep the flow on the wing and not leaving the wing. I haven't taken the proper class yet so I don't remember the terms from my basic design class. Ok, here's the question, would this be something the military would actually invest in? Would it be worth it to the military to have a STOL cargo plane? I just thought the technology was cool.
Electrically Reduced Noise Emission - IIRC someone was working on a system where electricity was run across a ring behind the nozzle of a jet engine. I don't remember the system exactly. It reduced noise emission of the jet by something like 60%. If anyone knows the system, please chime in. I think this might be of interest to the military if they don't already have some sort of system for it, like whatever the B-2 does.

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Are military aircraft designed such that they wouldn't need a morphing wing to give it better performance when taking off? That would allow it a shorter TO distance and then the wing could morph to give it better climb characteristics. After that point it would change again to give it killer supersonic performance? Has the military or even the civilian market looked at things like this?

Robust Avionics Technology? Perhaps "Robust Aerospace Technology Within The Atmosphere"? Avionics does not have anything to do with the four topics of your first post. Furthermore, someone is just trying to open up your imagination to technologies already in progress. To answer your questions regarding those issues you've mentioned, I will attempt a very simple, plain, and relevant explanation:

Morphing Aircraft Technology - Supercritical airfoils have been around a while. They include the aggregates of flight controls; both leading and trailing edge devices.
Robust Unstable Aircraft Programing - Yes, it's been around awhile. Sometimes, yes, a .22 caliber shot can ruin your day in some aircraft;depends what they are made of and where they are hit.
Increased Lift Devices - Yes, Boundary Layer Control (BLC), usually introduced onto the convex portion of an airfoil to increase pressure DIFFERENTIAL, generating more lift and not MAINTAINING it by introducing bleed air onto both inferrior and superior layers of the wing. Its been around awhile. Winglets; designed to keep high pressure inferior surface flow from interfering with low pressure superior pressure, aka wing-tip vortices. Relatively new technology, C-17, excellent example.
Electrically Reduced Noise Emission? - Never heard of it. However, baffling around and within the exhaust nozzles will reduce noise. Also, intake technology can be manipulated into creating a less noisy situation usually on the ground. In the air, above certain low Mach #'s, any noise, if present, will be behind the aircraft, if supersonic, perhaps a shockwave?

Your 2nd Post, it was the Vietnam Era fighters, (Century Series Fighters), that led and paved the way for the designs we have today. They were for the time and in most cases still are, the glory years of Military Aviation that will never be forgotten in the hearts of the men who flew and maintained them. VSTOL is the answer to your query of "better performance when departing". It seems as AE 101 has moved right along for you these past few days.

Roscoe, please jump in.

Sorry, I can never make myself very clear in these posts. This is from Professor William Crossley's website:

Genetic Algorithm Issues for Optimal Smart Actuator Placement. This research is investigating approaches for smart actuator placement to provide aircraft maneuverability without requiring hinged flaps or other control surfaces. The effort supports many of the goals of the Multidisciplinary Design Optimization focus efforts in NASA's Aircraft Morphing program. Computational studies are being conducted to allow comparison and selection of appropriate techniques for posing and solving an actuator placement problem. The work began with a geometrically simple wing model, but the approaches identified during this research have been applied to complete aircraft configurations. The problem statement and algorithm application are being used at NASA Langley by researchers working on the Aircraft Morphing Program. Research in this area has been cited twice as technical highlights for the NASA Langley Multidisciplinary Optimization Branch.

This is more of what I meant not flaps of all stripes. Here is the abstract of a paper from the same guy:

Recent advances in adaptive structures and advanced, compact actuators have renewed
interest in variable geometry aircraft that can change shape in flight to obtain better
performance during dissimilar flight conditions. These new morphing aircraft concepts may
allow for shape changes far beyond the well known variable sweep and variable camber
designs, like the F-111 or F-14 aircraft. Because of the potential for a wider range of shape
changes, significant effort has been put forth to develop strategies for the conceptual sizing
of such vehicles. However, a morphing aircraft may significantly change shape in flight in
ways that cannot be addressed by traditional sizing approaches. This paper presents a
recent improvement on the “morphing as an independent variable” sizing approach that
allows the use of continuous optimization techniques to size the morphing aircraft. Results
for several different missions, each with dissimilar segments, are presented and examined.
Based on the methods proposed in this study, future work can be focused on morphing
mechanism weight, implementation and design.

This is what I meant. I'm sorry for being unclear.

Would this be an example of a supercritical aerofoil? The mission adaptive wing?
http://www.f-111.net/images/NASA/NASA-index.htm.

Morphing aircraft tech? It seems DARPA were open to ideas!
http://www.darpa.mil/baa/baa01-42mod8.htm

Electric arc engine noise reduction research exhists. An interesting idea lordofbunnies. A quieter jet would be of some strategic and tactical value.The main beneficiaries could be civil aircraft, what with noise pollution issues being more prevelent today.

http://www.machinedesign.com/ASP/strArt ... rticle.asp

Another link;

http://www.physorg.com/news234.html. Brand new to me too.

Allenperos, about your point concerning baffles around the exhausts, it seems to me that the material and machined shapes of these baffles would also have an effect on noise too, as well as their positioning? I am not an aircraft mechanic, are exhaust baffles usually made of a ceramic material?

NASA has done some research to find out ways to reduce engine noise on the larger jets. They've found that changing the shape of the shroud at the exit of the fan (High bypass turbofans is the only thing I know this for) section. It looks kinda weird. It's like the normal exit of the fan part was taken as the x-axis and a sine wave was drawn across it and cut out that way... very odd looking because the exit was a wavy line. I don't know, the lady said it worked.

Elite 1K Joined: May 26, 2005 - 08:39 PM Posts: 1496

LordOfBunnies, as far as 'robust programming' for computer aided control have you read anything about the X-36? Specifically the RESTORE software.

http://www.aerospaceweb.org/aircraft/research/x36/
http://www.nasa.gov/centers/dryden/news/FactSheets/FS-065-DFRC.html

Great explanation of "noise abatement" in jet engines. Completely caught me off guard about electrical sine waves across the "X" axis around the exhaust. Very interesting and I will research this. Keep up the great posts!

"Genetic Algorithm Issues for Optimal Smart Actuator Placement" whoa!!! I do believe there is an example for this on an aircraft very near and dear to our hearts. It's been around. PM if you like.

Too many friggen smart people here. I have no clue what you guys are saying!!! Guess thats why im not a physics major!

-Aaron

Hasn`t wing warping technology been around since the Wright flyer?
Hardly "robust" though!

The Wright flyer had wing twisting when they pulled a cord. It was there version of control surfaces. I don't know how many people will understand what I'm saying if I start talking about NACA numbers, but I'm going to do it anyway Smile

. The Wright flyer didn't change the NACA number of the wing, just the AOA of part of the wing. That altered the direction of the forces and led to early steering mechanisms. What Dr. Crossley is talking about is changing the NACA number to give better performance at different flight conditions. Ok, here's an example, it's not feasible and I haven't taken fluids yet so it's not a good example, but I'll try. The plane would start out with a high lift airfoil, say a 6 series airfoil. The A/C begins climbing and starts changing the airfoil towards a supercritical airfoil as it approaches Mach 1. As the plane goes supersonic, the lift is less important b/c its possible to get as much lift from a lower drag airfoil. So the wing changes to that, and it's not only the wing that will change. The nose section might change to lessen drag. It's really fascinating stuff, though a little hard to find stuff that isn't on the F-14 and F-111.

LordOfBunnies sums up wing-warping quite nicely. Very well put, NACA numbers were explained very well synpa777 in his post. Fluids will further explain NACA numbers. Really do not have anything to add this post, very well put LordOfBunnies.

As far as the nose area of the aircraft is concerned, consider the retired Concord. At subsonic flight, it droops, not only for better visibility for Mach# operations, it retracts and forms a shock wave more conducive to a lower drag/better fuel economy type flight regime. All things considered. there are other drag considerations such as parasitic, wave, and form types. Overall, the most determinant of drag, a summation of and with the forth mentioned, total drag will decrease because induced drag is reduced? Or is drag from the cockpit considered a type of form/parasite drag? Things to consider for future posts.

Of course you are quite right, the Wright flyer "twisted" its wingtips with wires that also moved the rudder for lateral control.

There has been some work done on UCAV wings which can "morph" based on the use of the so called "lambda wing". This is a wing with a large "break" on the trailing edge and forms on inboard and outboard section. It is made up of a skin, spars and ribs forming the internal structure along with tiny electric actuators.

This wing has no hinged parts.
This kind of wing would not only open up mission envelopes but would also give superior roll rates and reverse roll rates.

Allenperos, your right on the button, parasite drag is generated by non lifting parts of an aircraft like the cockpit , fuselage, everything else is induced drag or pressure drag, with some slight overlapping.

Lordofbunnies, excellent last post I agree. Imagine an aircraft of the future filled with thousands of tiny motors moving all surfaces of an aircraft to suit the flight regime. It would be like a living animal!!! Birds do it quite well!

Who knows flying better than those guys. In my hometown, Canandian Geese migrate from Canada to Pennsylvania for the summer to spawn and get ready for the trip back to Canada and back again without the use of avionics!!! I couldn't do that, pilotage that is and with no maps they somehow manage!!!

synpa77 - May I add, parasite drag is the summation of all drag excluding drag due to lift such as (friction drag, profile drag, leakage drag - large transports) also they're are three other types of drag, (compressibility drag, drag rise, and wave drag). They are defined as follows:

Friction Drag - molecular activity around the airframe.
Profile Drag - Created by the frontal form of the aerospace vehicle in question.
Leakage Drag - Unpressurized aircraft creating a vacuum along the exterior.
Interference Drag - Additional drag created by two or more airfoils next to each other.
Compressibility Drag - At high velocities, the additional component of drag.
Drag Rise - An increase of density as the aircraft flows through a parcel of air.
Wave Drag - The formation of "Shock Waves"

Thanks for that Allenperos. A question?

What catagory does "Form drag" come under? Drag due to the shape of an aircraft.
Seems to me this is similar to pressure drag? I know pressure drag is created by separation of air flowing over the aircraft creating turbulance and then pockets of differing pressure seen in the wake of aircraft.

Drag can be difficult to calculate, hence windtunnel testing. Even then there is no substitute for real world flight testing.

We can learn a lot from birds, they have been flying a LOT longer than we have!

Forum: Technology

Robust Aviation Technology