Loading

Module 1: Aircraft Configuration Design

Note di Apprendimento
Study Reminders
Support
Text Version

Achieving Natural Laminar Flow

Set your study reminders

We will email you at these times to remind you to study.
  • Monday

    -

    7am

    +

    Tuesday

    -

    7am

    +

    Wednesday

    -

    7am

    +

    Thursday

    -

    7am

    +

    Friday

    -

    7am

    +

    Saturday

    -

    7am

    +

    Sunday

    -

    7am

    +

Let us look at now some studies related to supersonic transport and supersonic business jets.There are 2 things attempted here one is one aim is to try and create a supersonic laminar flowand to maintain it for a long condition for a long time and also to experiment with techniqueswith which the sonic boom can be reduced.(Refer Slide Time: 12:41)
Laminar flow or maintaining laminar flow on an aircraft for a large part of the large fraction ofthe aircraft surface has been the holy grail of Aeronautics, right from the beginning people haveattempted to achieve laminar flow. One way of achieving laminar flow is called as active laminarflow control where we use techniques like boundary layer suction or boundary layer blowing toproactively create laminar flow, but this requires a lot of energy and power.
What people would like to have is passive or natural laminar flow control in which we are notgoing to use any additional device such as the blower or a suction thing, but we do very carefuldesign of the wing. So, you alter the wing cross section, so, that you can change the pressuregradient and using the changes in the pressure gradient itself you should be able to maintainlaminar flow over a large region.
So, one project called as SCRAT under DRELFGE or subsonic research aircraft testbed for theDRE laminar flow glove experiment was carried out in which an aircraft was taken up by NASADryden Flight Research Center and on one side on one wing as you can see on the port wing, asmall glove was created where a laminar flow area was artificially created and then tested duringflight testing.(Refer Slide Time: 14:11)
Another example of this particular experiment is the General Dynamics F-16XL under theSCRAMP project in 1977 to 79 SCRAMP stands for supersonic cruise and maneuver prototype.So, this is the crank arrow delta wing configuration. So, the electronic flight control system of
the F 16 aircraft was tweaked to allow the aircraft to fly at a higher angle of attack. And with thisthe volume available for the fuel was increased and the range also was increased as a falloutparameter.
As I mentioned, there is a crank arrow delta wing with the double sweep. So, inboard wing hasgot a very high sweep that you can see at this portion. This is a very high sweep. The aim of thisis to reduce the supersonic drag. But you also want to have better handling and maneuverabilityat low Mach numbers or Mach number less than 1 subsonic part numbers for that we have thisparticular outboard wing with a lower wing sweep.
So this aircraft took part in the enhanced Tactical Fighter competition conducted by the US AirForce in 1981 to 84. It lost to F 16 Eagle, a modified version of F 16 Eagle, so it was stored inthe adverse Air Force Base in Mojave. So, let us have a look at our video
Using a wing originally designed for a supersonic airliner, the company began the supersoniccruise and maneuvering program. The wing was not unlike that of Sweden's drokken fighter, aDelta with a crank arrow or bent leading edge. According to designers that giant aero designgave the aircraft substantial gains in payload and range without sacrificing agility. In 1980, theAir Force and General Dynamics began modifying a few pre-production F 16 into what wouldbecome the first F 16 XL all the F 16 e by the Air Force.
The XL name would stick becoming the definitive delta wing by changing the exhale wingrequired along the fuselage. Over 4 and a half feet were added by lengthening the airframe.Extensive use of composite materials, then new to the aircraft industry gave the exhale more thandoubled its original wing area while gaining less than a ton and a half in total weight. Once themodifications were complete, the first XL was ready, having the sub drokkan to familiarizehimself with the crank delta wing. Test Pilot Jim McKinney took the XL skyward.
On July the 3rd 1982 initial flight show the designers were right about the potential at the crankterror wing. Joined by the 2 seat belt version in October 1982. The aircraft perform like a jobgearing up to 16500 pound bombs cleaned up. The exhales could also be punishing ground attack
aircraft. The exhale had over twice the payload capacity of the standard Falcon with almost a50% increase in range. The bigger wing also meant for a much smoother ride at lower altitude. In1981, the US Air Force started the advanced Tactical Fighter program.
The goal replace the aging F4 Phantom in the road of ground attack. McDonnell Douglas with itsmodified 2 seats F15 B and General Dynamics with the XL were the main comparatives. Duringthe competition, the exhale had demonstrated an ability to lift a heavy array of weapons. On onemission, the single seater dropped 12500 pound bombs, the equivalent of carrying 2 full sizedcars on the wings. The exhales never met one important goal super groups. The ability to flywithout the alphabet lit at supersonic speeds.
Zipping over enemy lines without the huge infrared signature of an afterburner was becoming amust in modern warfare. The shutdown between the F15 e and the XL continued through early1984. Then the Air Force announced their decision. They had chosen the eagle over the XL.Some experts claim that the XL was the better aircraft, but the desire to keep the F15 line open inSt. Louis played a role and the design whatever the case, the F15 e came out ahead. After losingthe Tactical Fighter competition.
The 2 XL were put in storage first and Edwards and later in Fort Worth. In late 1988, NASAproposed using the XLs for advanced supersonic air flow testing, they took over the aircraft in1989. They were soon modified to demonstrate the benefits of something called laminar flow. Toachieve laminar flow, the turbulent air on the surface of a wing must be removed. The XL wasgiven a special wing mounted fairing filled with millions of microscopic holes each board with alaser beam.
NASA then added a vacuum pump to draw the disturb layer of air inside the wing. This allow thesurface air flow to become smooth or laminar, the benefit of laminar flow is less drag. Theresults of this experiment would dramatic a plane that could not achieve super crews before wassuddenly capable of non afterburning supersonic flight. NASA has recently upgraded the originalXL in anticipation of follow on testing of these high lift and laminar flow experiments. These
programs part of the high speed civilian transport program should keep both of the XLs activewith NASA well into the next century.(Refer Slide Time: 21:23)
Now, to carry out the supersonic natural laminar flow experiments, this aircraft was actuallyrevived from the storage in 1998. And after revival from storage, it was modified as follows. So,a porous titanium LFC linear flow controlled glove was created in the wing there are laser cutholes of very small diameter 63.5 micro millimeter diameters. So, the gaps between these wasmaintained as 0.245 mm to 4.4 mm there was a variation of gaps and the area of the glove wasabout half square meter. So, such a glove was created and inserted on the wing.
So, the aim of this particular glove is to suck away the turbulent airflow this is a active laminarcontrol. So, use you are through these holes, the laser cut holes we are going to suck away theambient air and restore laminar flow and reduce the drag. Now, it was founded during thisexperimentation of the aircraft, the aircraft was able to fly supersonic without the need forafterburner this was not something which was planned, this is just something that happenedbecause the drag reduced substantially.
So, therefore, without afterburner the aircraft was able to get the thrust that could create force tomake it fly supersonic. So, then passive fiberglass and foam glove was mounted on the starboardwing to investigate the supersonic laminar flow and in that particular wing, it was decided that75% of the wing and 60% of the leading edge on the middle to third portion will become active.
So, during this experiment, it was found that by doing this you could maintain laminar flow ornearly half of the wing.(Refer Slide Time: 23:20)
So, that is a huge achievement. So, if you look at how supersonic natural laminar flow is created,basically the aim is to create laminar flow at Mach numbers more than 1 without any activeboundary layer suction methods. So, NASA has done a season experiments on a small stubmounted below the fuselage and it was this is a CFD prediction and this is the actual flight testinformation.(Refer Slide Time: 23:49)
So, how do you achieve supersonic natural laminar flow one mechanism is you use wings withlow sweep and sharp subsonic leading edge. So, you can see that this is one possibility, you have
low sweep but very sharp leading edge. So, with that sharp leading edge, you get a particular endlike this or you could use the conventional approach where it is slowly increased to high valueand then comes down slowly.(Refer Slide Time: 24:20)
Let us look at some supersonic business jets. There is one which is in the pipeline for a long timeby a company called Aerion funded by Boeing mostly Aerion AS2 to is a very popular conceptnot yet seen the light of the day. This is supposed to be a 12 passenger supersonic transportaircraft which would carry around which will fly at Mach number 1.4 up to 8800 kilometers. So,this comes under the category of business jets because 12 passengers is too less to make moneyin commercial operation program cost is 4 billion dollars.
The unit cost is claimed to be 120 million dollars for aircraft with 4 seats this is a very high costfor an aircraft with can carry many more passengers with more facilities it may cost actuallyeven less than this.(Refer Slide Time: 25:20)
So, here are some pictures and here is a an indication of how the configuration is similar to thatof F-104 star fighter aircraft. We have not done it to scale but we have just enlarge the picture so,that we can keep them definitely one over the other to give you an idea that they are very similarlooking with similar sweeps.
Aerion as to supersonic business jet program received a major boost recently when Airbus signedup for a partnership which will help to complete the design of the aircraft and prepare forcertification and manufacturing. According to Aerion, the collaboration will support the Mach1.6 100 plus million dollar 12 passenger as to at least through service century, with finalarrangements for series production still to be confirmed. I have always had the confidence thatthis would make it into service.
It is a question of when not if, but clearly the technological partnership with Airbus is a greatstep forward and will lead to the commercialization of an Aerion. Airbus is very pleased to bepart of this collaboration with Aerion. It is a technology change a knowledge exchange, we arevery interested in their sonic laminar flow modeling that they have done and design, we think wecould tribute to manufacturing certification, folly techniques.
So it is a total collaboration effort to take this to not only just the business plan, but all throughthat is writing in the margins. The Aerion AS2 trigent is revised design from the earlier twinengine design and promises to deliver longer range and a larger cabin. The cabin is now
comparable to a Gulfstream G 550 in height at 6 feet 2 inches in width at 7 feet 3 inches, thecabin length was expected to be 30 feet long, this new aircraft configuration is really driven bymarket we did an extensive market refresh.
And we found that width was something that people had a great deal of value in much more sothan length. And so you know that led to the new configuration. Also the JTA D although is awonderful engine. It is old, heavy and noisy. And we clearly need a new core. So we are goingback to the engine manufacturers to find the best core that will meet our service marks Aerions isin opening in the market for the supersonic business jet even if the jet may not always be used toits full performance potential.
The jet will cruise at Mach 0.99 in Aerion where supersonic speeds are prohibited, such as theUnited States. Over water the jet will travel at speeds of Mach 1.4 and 1.6 and crews at speeds ofup some Mach 1.2 over populated areas without a sonic boom reaching the ground. I think thatthe ability to have speed but still the ability to land at normal business airports gives greatflexibility and certainly one of the areas that we have found that there has been phenomenalreception is in the Far East where the distances are so vast that it takes forever to get from oneplace to another and being able to get there and half the time is a great boom.(Refer Slide Time: 28:45)
Lockheed Martin has also come up with the project in associated with NASA to develop thequiet supersonic technology. This is not going to carry too many passengers. This is a prototype
about 96 feet 8 inches long and 29 feet wingspan 14 feet height. So the aim of this project whichis funded by NASA is to reduce the intensity of sonic booms and to study the effect of the sonicbooms onto the mainland passengers in USA. So this aircraft is going to fly at Mach 1.4.
And it is going to create a sound pressure level of less than per 75 PLdB PL stands for perceivedlevel and dB is the unit for pressure. The max take-off weight of this aircraft, 24,300 pounds. Itsempty weight is just below 15,000 pounds, and it can carry 8000 pounds of fuel. But with somuch of fuel and so much of empty weight. The air craft can travel only with over 600 payloadsfor full range so it is not really a very efficient aircraft. But it is very good for experimentationfor what it has been built. So let us watch a video of Lockheed Martin experiment in action.
Sonic Boom becomes Sonic thumb. America's top scientists are working on a plane that can flyfrom LA to the big airport. In just a few hours, Lockheed Martin and NASA partnered up todevelop a quiet supersonic plane in the X59. The proposed single pilot craft has a wingspan of49.5 feet. It is 94 feet long and weighs 32,300 pounds. Total fuel capacity, NASA says the X 59will be powered by a General Electric f414 engine. This is the same engine used by the FAA218fighter jets.
The craps hole is designed to abate the noise from shockwaves traditionally associated withMach Speed travel during that shockwaves come together and create loud Sonic Boom. TheSpace Agency says the X 59 is decided to separate the shockwaves resulting in much less noisereaching the ground. The aircraft first flight test is scheduled for 2021 buckle up. Canadianengineer designs Mach 24 aircraft antipode Charles Min bardia has done it again.
The engineer just released concept designs for another supersonic aircraft, antipode. The plan hasbeen conceptualized to carry as many as 10 passengers up to 12,430 miles in under an hour,which is speeds as high as 16,000 miles per hour. If you can imagine the world's fastest carclocked in at about 270 miles per hour at 16,000 or Mach 24, which is a little over 18,000Antipodes estimated to be capable of traveling from London to New York and just 11 minutes offlight that currently takes 8 hours.
Antipode comes on the heels of November 2015 aircraft concept the screamer, which promisedto travel at Mach 10 speeds, but was rife with design flaws. Following screamers announcementit was confronted with Sonic Boom and heating issues that would render the conceptnonfunctional. Antipode is bombarded his response to screamers flaws. But if you are looking tocatch a ride anytime soon, do not hold your breath.
The aircraft is years away from fruition as most of the technology required to make it functionalhas yet to be developed. But now that the DeLorean might be back in production, you might noteven need a Mach 24 aircraft bloodhounds set to break land speed record top 1000 miles perhour. The current land speed record is held by the thrust SSC which broke the sound barrierwhile traveling at 763 miles per hour in 1997. Now its developers have taken on the challenge toreach 1000 miles per hour with a new car called the Bloodhound SSC.
The 1000 mile per hour car weighs 7.8 tons and measures 13.4 meters long and is designed totackle the severe aerodynamic challenges. It is carbon fiber and titanium plated bodywork is builtto withstand a tremendous amount of pressure 2 computer winglets at the head of the car willhelp keep the nose grounded to achieve its record breaking speed. The bloodhound is equippedwith a V 12 racing engine that powers an ej 200 jet engine and a hybrid rocket engine.
The jet engine typically found in the Euro fighter jet typhoon takes the car to 100 miles per hourin just 5 seconds. When the car reaches 350 miles per hour at around 15 seconds, the rocket isfired, accelerating the car to 1050 miles per hour in another 25 seconds. At its peak speed. Thebloodhound would break the land speed record covering 1 mile in just 3.5 seconds. The rocketwill then shut off before power brakes.
And parachutes will be deployed to bring the vehicle to a stop to bloodhounds test drive is set totake place in the hack scene pan desert in South Africa in 2016. Sonic Boom from fighter jetcaused tremors in New Jersey, while some panicked residents called 911. After feeling theground shake earlier today, others took to social media to ask what caused the shaking. OnThursday afternoon a series of tremors were felt in parts of the Northeast United States makingresidents think they were experiencing multiple earthquakes.
The real culprit was a supersonic flight test conducted on 2 fighter jets near the Patuxent Rivernaval airbase in Maryland, which produced a series of sonic booms. A total of 9 sonic boomswere reported in 90 minutes from 1:30pm to 3pm. The US Geological Survey center the boomsover hemington with tremors felt from South New Jersey to Long Island and the booms wereheard as far away as Connecticut.
A temperature inversion which puts warm air higher up in the sky may have caused the sonicboom to be felt over such a large area as sound waves travel farther and warm air. A Navyspokesperson said the supersonic flight tests were conducted almost daily in the area but wererarely felt on land. Supersonic passenger flights will soon be a reality. A new airliner that boastssupersonic speeds is set to revolutionize air travel.
Once it takes flight in 2023 boom technologies planned to supersonic aircraft will have a cruisespeed of 1451 miles per hour 2.6 times faster than any other airliner. While a flight from NewYork to London would typically take 7 hours on a commercial flight, the trip would take a littleover 3 hours on a supersonic airliner. The Mach 2.2 aircraft will have 55 seats, each priced atabout 5000 US dollars for a round trip ticket.
A one third scale prototype called the XP 1 will begin test flights in 2018 to demonstrate andrefine the key technologies required for supersonic travel. Unlike the now retired Concorde andits notoriously loud sonic boom, the boom aircraft will have turbofans where noise reduction andwould not be much louder than a normal plane. The company does have some hurdles to facebefore their project comes to fruition. Supersonic flights are still banned in the US but withfederal laws currently set up for renegotiation that could soon change.
That is all thanks for your attention.