Supragility and super agility aircraft

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DangerZone

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Asuming that most people know about supermaneuverability of some modern jet fighters, I wondered if there might be some information about supragility aircraft on the internet available?

Supermaneuverability relates to aircraft which maintain control and manoeuvering ability in exceeding what is possible by pure aerodynamic machnisms. Super agility goes beyond that, it means taking advantage of the aircraft body/design/technology to improve performance by taking advantage of effects which this supermaneuverability uses at low speeds, making the aircraft a better performer at greater velocities too. Supragility is a term I thought would be better for aircraft which have improved performance even in situations which are disadvantagous for other aircraft, for example having great additional performance during the stall or when flying backwards. A Pugatchev Cobra is an example of familiar supermaneuverability in which an aircraft can fly controlably backwards for a short period of time. An analogy best describing the features would be the difference between a gymnast and a runner. A gymnast can sprint, spin, flip, handwalk or do something inverted in similar acrobatics and always finishes moves/jumps in a controlled position while a runner hardly ever uses the advantage of acrobatics. Since developing such platforms/aircraft is fairly new, there is limited reading resources on the internet. I am looking for sources in English, French, German and Italian since these are the languages I understand, but Russian could also be a good source with the modern translation tools.

My interest is supersonic homebuilt airframes which can handle supragility performance. In other words, compensating size for performance: the smaller/lighter the airframe with a certain powerplant the better the performance and thrust to weight ratio. There are different approaches concerning supermaneuverability in the USA, Europe and in the East and it surprised me that sometimes one region would consider something impossible which might be performed in another area. For example, the Herbst maneuver is considered to be impossible without thrust vectoring yet it can be achieved without it if one has insight to a different perspective. Hook turns with higher than 20Gs are also considered impossible, so are controlled yaw spins or Bells, the Pugatchev Cobra was also considered by many as a trick for some time, there are quite a few examples in recent history. Works like the phD of Antony Kutchera or Darrol Stinton books/articles are a bit limited to moder jet fighters and similar sizes of aircraft, so it is hard to find good resources with smaller and faster liquid propelled aircraft. Has anyone stumbled upon books/articles/research which would be interesting for the field of a small homebuilt supragility aircraft?

Since this idea relates to new deisgns and technology, the internet is a bit limited in resources. If anyone knows where to find additional info feel free to share or send a private message. It seems there are mentions of supermaneuverability but if super agility or supragility go under a different name in English written research, it would be good to know.

Supermaneuverability - Wikipedia, the free encyclopedia
 

Himat

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I would guess most information on this subject is kept secret.

On the other side, I do think I have stumbled across pieces of information you seek when searching the internet for something else. Something like a master or PhD thesis on modeling the dynamics of an aircraft and building the mathematic model of the aircraft. It might be that quite some information is there, but not with the superagility or similar keyword attached. First when reading papers on how to model, determine controllability of the system and other "basic" subject, it is possible to se that the application at hand is super agile fighter aircraft design.

(I guess it's like being on a congress on sound propagation in the ocean and all military scientists talk about how sound propagate from a small explosive charge somewhere in the ocean. It's not stated, but everyone in the business know what the applications are.)
 

DangerZone

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I would guess most information on this subject is kept secret.

On the other side, I do think I have stumbled across pieces of information you seek when searching the internet for something else. Something like a master or PhD thesis on modeling the dynamics of an aircraft and building the mathematic model of the aircraft. It might be that quite some information is there, but not with the superagility or similar keyword attached. First when reading papers on how to model, determine controllability of the system and other "basic" subject, it is possible to se that the application at hand is super agile fighter aircraft design.

(I guess it's like being on a congress on sound propagation in the ocean and all military scientists talk about how sound propagate from a small explosive charge somewhere in the ocean. It's not stated, but everyone in the business know what the applications are.)
It is natural that everyone keeps some information secret, even though those who have the capacity to anticipate and read between the lines may understand basic principles behind some application easily.

However, these jet fighter programs are limited to three axis control (pitch/roll/yaw) + thrust vectoring (4th control, thrust is also primary control) which limits an aircraft to supermaneuverability at subsonic speeds. Supragility includes a bit more of control at higher speeds (transonic and supersonic) and controlled strafe, tuck, yaw about 360 degrees in flight, fully controllable stall and reverse flight in subsonic speeds. Most of the jet fighters are heavy, consume a lot, need the ability to carry tons of weapons and have a limited range. The needs of a homebuilt supragility aircraft are different, it does not need weapons or such heavy mass. Thus Antony Kutcher's thesis and similar works are ok for reference but not much for supragility. It would be great to see what you found, could you please point me in the right direction?

There's a lot of interesting stuff related to sound and light propagation in fluids as dense as water. This time the fluid is atmospheric air, so if you find anything usefull for this topic please be so kind to share.
 

Himat

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Trouble is that I did read it, but did not save a copy. Trouble is even if I saved a copy I would not remember where I saved it. Anyway, I do think I was searching for information on how to make physical models of coupled systems. I'll post if I get across it again.
 

autoreply

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I frankly don't understand your question?

Maneuvering is pretty basic dynamics. Once you allow both dynamic and static stability to go negative (due to FBW), you'll get a more maneuverable ship, but that's about it? If supersonic, your limit is going to be the occupant anyhow, unless stall speed is in the Starfighter/X15 territory.
 

WonderousMountain

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They do not exist.

Aerobatics are all there is. There are some papers on post stall maneuver theory applied to fictional airplanes. Of course there are the military air combat craft. Maybe you could talk to some pilots of those. I don't know if anyone here can advise on the possibilities. It's a pretty intense exercise to achieve supraManeuverability. Good luck though, maybe there's a super aerostructuralist lurking around here somewhere.
 

Himat

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Maneuvering is pretty basic dynamics. Once you allow both dynamic and static stability to go negative (due to FBW), you'll get a more maneuverable ship, but that's about it?
With a viewpoint from radio control models and dynamic system control engineering I'm not sure.
Radio control models designed for the purpose of high maneuverability, also post stall are both static and dynamic stable, yet show great maneuverability, even post stall. To me the question is as much about what control forces that are accessible and how to apply them to give a desired change in attitude. To me an example of super agility in an aircraft would be the possibility to fly with the attitude of the aircraft skewed from what the flight trajectory in a "normal" airplane would dictate.

But then I'm maybe far from what DangerZone have in mind.
 

WonderousMountain

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Perhaps a 2 axis symmetric airfoil with flaps on front and back, with high speed drag brakes with hand responsive mixed controls would be able to do some new tricks.

:whistle:
 

DangerZone

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I frankly don't understand your question?

Maneuvering is pretty basic dynamics. Once you allow both dynamic and static stability to go negative (due to FBW), you'll get a more maneuverable ship, but that's about it? If supersonic, your limit is going to be the occupant anyhow, unless stall speed is in the Starfighter/X15 territory.
The question is about new technologies which assist in achieving better performance than what is achieved by only classic aerodynamics. For example, thrust vectoring enabled performance and maneuvers which led to supermaneuverability in aircraft like the X-31 or the Su-30 series. The intention of this thread is asking for internet (or other available) sources which relate to research, documents, documentaries, videos or other information about supermaneuverability AND super agility in modern aircraft, not necessarily jet fighters but any aircraft including homebuilt.

With a viewpoint from radio control models and dynamic system control engineering I'm not sure.
Radio control models designed for the purpose of high maneuverability, also post stall are both static and dynamic stable, yet show great maneuverability, even post stall. To me the question is as much about what control forces that are accessible and how to apply them to give a desired change in attitude. To me an example of super agility in an aircraft would be the possibility to fly with the attitude of the aircraft skewed from what the flight trajectory in a "normal" airplane would dictate.

But then I'm maybe far from what DangerZone have in mind.
This is a good analogy because more than twenty years ago the idea of enhancing RC aircraft led to drones which can outperform many sophisticated jet fighters of fifth generation. The clue is in size, mass and thrust to weight ratio combined with airframes of extraordinary design. Thus importance is in airframe design, becuase with modern composites there are almost no limits in what we can achieve, including suprability.

More than a decade ago, we were skiing with small skis, custom made to b fast, maneuverable and enable skiing backwards. This allowed us to do tricks, flips, jumps, rotations and a lot of stuff we did in gymnastics, which was impossible with classic skis. Today, this is a global fun and there are tournaments for skiing stunts. It takes some habit to get used to negative stability when skiing backwards, but the idea made me think about if it would be possible to design an aircraft which might have static stability with both positive and negative dynamic stability interchangeable in flight on demand. Throughout the years and tests, the idea was taking shape and the principle was tested in subsonic flight. However, supersonic flight requires the airbody to be inherently stable during the mach buffet at transonic speeds and be performant at supersonic speeds, so more testing would be needed and it is time/means consuming. The redistribution of control forces and a different control system is needed to achieve that, because the classic stick/rudder/throttle has geometric limits and would not allow supragility. It does allow supermaneuverability so there is something I can learn from their behavior and limitations.

Today, there are larger drones which can do some high speed stunts but they have mostly a fixed negative static stability and controll is provided by computers. This reduces redundancy and is not a good solution for a homebuilt design and humans to fly. I want to have full controll in all aspects of flying and have means to revert to static&dynamic positive stability instantly in a split second if there is need. This means true supragility, and so far not many platforms have shown such abilities. That's why I opened this thread, cause maybe someone has information about similar projects in the recent past.

Perhaps a 2 axis symmetric airfoil with flaps on front and back, with high speed drag brakes with hand responsive mixed controls would be able to do some new tricks.

:whistle:
Controls have to be different to be able to achieve supragility. The implementation of speed brakes proves that aircraft lack control with only primary controls (pitch, roll, yaw, thrust - stick/rudder/throttle). Thus people invented flaps, slats, air brakes, spoilers, and similar assisting control mechanisms. However, these are only lift augmentation devices, thrust vectoring is the first control assisting mechanism which allowed better performance beyond increasing lift. Thrust vectoring shows that by thinking outside of the box, it is possible to achieve more with the same thrust. All it takes is a good feasible idea and a solid reliable mechanism to make this a reality.

I was very sad when Branson's Virgin Galactic Spaceship Two crashed, and it took me some time to figure out how and why this happened. I have deep respect for people who have spent hours and hours of thinking and building to make flying improvements or try to reach space. They have made an extraordinary design which worked for some time but it made me think if I could reduce even more any possible chance of risk during high speed flight and static/dynamic stability change. As a passionate reader, I will be open to any suggestion about similar new designs and technology that someone could point to.
 

TFF

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The problem you ask about cant be done with our knowledge. Aircraft act in a medium of air; you need a ship that act against the medium of air.
 

DangerZone

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https://www.youtube.com/watch?v=ZW7oeSm7zZ0

=no thrust,no vectores...
but STATIC stability!!!
This looks like some sort of Kasper gliding wing, similar to those first explored by Lippisch for supersonic flight when working in Messerschmit.

The Messerschmit Me163 Komet did go supersonic in 1944 with that kind of configuration without horizontal stabilizers, but it lacked other elements needed for super maneuverability. Lippisch and other engineers ran into the same problems as Yuri Aleksander Pobedonoscev (please don't mind my spelling) did in the 1930s when going supersonic at 630m/s, the problem of control. They were pretty good for their time, even though flying the Komet was just scary. I read some testimonials of German Komet pilots who were not afraid of high speed buffet (they could not hear the sonic boom but felt it) or being hit by Allied forces as much as the risk of fuel spillage which was highly toxic or acidic.

Interestingly, Chuck Yaeger's X-1 which breached the sound barrier in 1947 did not have such sweep but the X-15 had tapered wings with a leading edge sweep angle closer to that of the Komet.
 

DangerZone

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The problem you ask about cant be done with our knowledge. Aircraft act in a medium of air; you need a ship that act against the medium of air.
It depends on what your knowledge is. The first teaching of Zen in martial arts is not to oppose a stronger opponent but to use his energy against himself with proper technique. The same applies to aircraft, vectored thrust is the same thrust used in a different way, the effect is enormous and would seem impossible to a person without knowledge of vectored thrust.

There were private homebuilt aircraft flying faster than the speed of sound, there's plenty of homebuilt acrobatic aircraft, please be so kind to explore that and contribute by sharing rather than saying something is impossible. Just a hundred years ago, most people were saying it is impossible for humans to fly. Let's not go back to such ideas but step forward into the future.
 

Himat

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...This is a good analogy because more than twenty years ago the idea of enhancing RC aircraft led to drones which can outperform many sophisticated jet fighters of fifth generation. The clue is in size, mass and thrust to weight ratio combined with airframes of extraordinary design. Thus importance is in airframe design, becuase with modern composites there are almost no limits in what we can achieve, including suprability.
And somewhere someone interested in all things flying, read, look at the pictures and get hooked:
600px-HIMAT.jpg

Rockwell HiMAT - Wikipedia, the free encyclopedia
 

DangerZone

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And somewhere someone interested in all things flying, read, look at the pictures and get hooked:
View attachment 36735

Rockwell HiMAT - Wikipedia, the free encyclopedia
Rockewell had great ideas/concepts in the past, it seems they might have been ahead of time or too good for the feasibility capacity of the era. The XFV-12 was a good idea but too ambitious/large to become successful. Their next project HiMAT was a different approach, instead of using large/clumpsy parts of other aircraft to reduce expenses they minimized the airframe and constructed with modular design. The sparcaps were carbon/graphite fibers, leading edge glass fibers, titanium engine exhaust and some other parts but it also had steel parts. It showed great lateral and longitudinal maneuverability, yet high sweep produced a high stall speed and some other complications. The following X-31 supermaneuverability aircraft outperfomed many other concepts of the time yet perished when a pitot tube froze because there was no manual override to let the pilot take over if computers fail. It seems this shook the company's business cause they did not advance these concepts further yet some other nations leaped forward in the field. Today many fighter aircraft use thrust vectoring and the Russians have very interesting advancements, the Su-30 series aircraft and the PAK-FA are considered most advanced at the moment. Their choice of materials shows to be justified cause the Su-37 flew to an altitude of 37km, higher than FL 1230. This is a massive aircraft, so there's no dilema that improvements can be made by reducing the size, just like Rockwell did with the HiMAT. The HiMAT was not designed to handle such radical altitude and attitude changes, so the materials and airframe should differ to enable real supragility. Steel and rubber have some nasty reaction tendencies to sudden temperature changes like Richard Feynman demonstrated to the investigation team of the Challenger disaster. I'm not saying these materials are inadequate for supragility aircraft use per se, but structural parts should be chosen and designed taking these properties into consideration. Titanium is hard to find/buy, machine and weld but it offers advantages over steel in some aircraft construction applications. If the homebuilt airframe is small enough then the expenses are not that high and can be justified. And this is what made the HiMAT such a great aircraft, the lighter the airframe/drag and higher the power/stiffness - the better the ride. Just like fast motorcycles, the industry lags behind private owners who turbocharge the engines and improve the bike frames. I specially liked some HiMAT airfoil/airframe solutions for transonic performance, which convinced me years ago that smaller/lighter is the way to go to achieve suprability.

Thrust vectoring is certainly useful, may I suggest drag vectoring?
Would you be able to elaborate or explain what you meant?
 

WonderousMountain

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Wingtips, fore and aft body are obvious place for deployable drag panels.

Other possibilities for front or back wing surface area expansion or contraction, like zap flaps. Deployable drag on landing gear, or vertical tail.

Of course, you could get a lot of ability just from a single joint about midway along the wingspan.

Most of this would take a radical departure from tradition, but the manufacturing ability is ready. It's up to someone with the courage and intellect to make the leap.

LuPi

I forgot to mention, a duct with small deployable inner & outer triangles would be a simple structure that would have a good retracted/deployed drag ratio
 

DangerZone

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Wingtips, fore and aft body are obvious place for deployable drag panels.

Other possibilities for front or back wing surface area expansion or contraction, like zap flaps. Deployable drag on landing gear, or vertical tail.

Of course, you could get a lot of ability just from a single joint about midway along the wingspan.

Most of this would take a radical departure from tradition, but the manufacturing ability is ready. It's up to someone with the courage and intellect to make the leap.

LuPi

I forgot to mention, a duct with small deployable inner & outer triangles would be a simple structure that would have a good retracted/deployed drag ratio
Ok, now it's easier to understand what you meant.

You are right that a departure from tradition was needed to achieve supragility, thus landing gear gave way to vertical take off and landing and tail was removed for a better usage of aerodynamic forces. There is a way to use drag on demand by geometry change, which resolves the need for any spoilers or flaps upon landing. It could be said that the advances and affordability of high quality composite materials allowed us to design better options than to follow industry and large design bureaus.

Ducts can come in varous forms and sizes, so a duct can be designed to have increased drag if needed or to be closed to the relative airflow so it would have no effect on body aerodynamics. Which specific triangles did you have in mind when mentioning that example?
 

Sockmonkey

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One idea that I'm quite in love with is fluidic controls. Instead of altering airflow with moving structures like flaps, compressed air is blown through slots in all control surfaces. Interesting thing is, that you can stick such slots all over and have nearly all parts of the airframe act as if they were control surfaces.
 
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