engineering.purdue.edu · Web viewDevelop an environmentally-sensitive aircraft which will provide our customers with a 21st century transportation system that combines speed, comfort,

SRR Endeavour 11 Feb 2010

Page 1


Table of Contents Mission Statement..............................................................................................................................3

Customers & Market...........................................................................................................................4

o Customer.........................................................................................................................................4

o Market.............................................................................................................................................5

Competitors........................................................................................................................................6

Concept of Operations (CONOPS).......................................................................................................8

o Customer Requirement & Solution.................................................................................................8

o Aircraft Payload & Passenger Capacity...........................................................................................8

o Cabin Layout....................................................................................................................................8

o Design Mission..............................................................................................................................10

o Typical Operating Mission............................................................................................................13

System Design Requirements...........................................................................................................16

o QFD / House of Quality.................................................................................................................16

o Benchmarks...................................................................................................................................18

Future Technology............................................................................................................................20

Initial Sizing.......................................................................................................................................26

o Sizing Code....................................................................................................................................26

o Constraint Diagram.......................................................................................................................26

o Estimated Values...........................................................................................................................26

Summary...........................................................................................................................................32

The Next Step....................................................................................................................................33

Reference..........................................................................................................................................34

Appendix...........................................................................................................................................36

Page 2


Mission Statement

The XG Endeavour concept represents a significant leap forward in 21st century green performance and technology. But before the design of such an involved and detailed project could get underway, the XG members made a combined effort to define a concise mission statement clearly outlining their goals for the project.

Develop an environmentally-sensitive aircraft which will provide our customers with a 21st century transportation system that combines speed, comfort, and convenience while exceeding NASA’s N+2 criteria.

The above mission statement clearly outlines what the group needs to accomplish, and will strive for in making sure the final design meets all of the proscribed criteria.

A crucial part of the mission statement designates that the aircraft must be environmentally-sensitive. This implies several things, the first of which is the stipulation that the design and manufacturing processes, as well as the final product, have as little environmental impact as possible. An aircraft can damage the environment in many ways, from the consumption of finite fossil fuels, to harmful emissions, to noise; all of which must be considered in a complete green project.

In spite of these tight constraints, the Endeavor will be designed with performance in mind, incorporating a shorter takeoff length than similarly-sized competitors and making no sacrifice in speed or range. It will accomplish this by integrating advanced concepts such as the GE and Pratt & Whitney-developed propfan engine, promising a 35% reduction in fuel consumption over similarly-sized turbofans, and solar film, which will aim to satisfy all the internal power requirements of the aircraft, leaving the engine to generate thrust alone.

Ultimately, any design must begin with an understanding of the criteria defined by its customers. In this regard, XG has based its design on both the performance benchmarks as outlined by NASA’s N+2 guidelines, as well as an extensive in-house market study. Using these tools, the size and configuration of the aircraft in will be determined in order to maximize the performance of the aircraft while offering the benefits of the XG concept to its best-suited market sector. The table below highlights the NASA N+2 criteria which the final design must meet:

Page 3

SRR Endeavour 11 Feb 2010Table 1 : NASA Subsonic Fixed Wing Guidelines

Customers & Market

o Customer

All sorts of different people buy business jets, however they all have certain needs in common. First and foremost, anyone who buys a business jet is looking to get from one destination to another quickly. Without speed, a business jet has no chance of being successful. Along with speed, comfort is also a must. Keeping in mind that the typical use of an aircraft will be different for each customer, cabin comfort must scale to their needs. Most business jets operate at less than full passenger capacity, and most people who travel on private jets are looking to do so in a comfortable fashion. A private jet must also be reliable. Each time the owner wishes to use the particular jet, it must be capable of accomplishing its design mission. Finally, a private jet must be capable of providing a level of convenience that commercial airliners cannot. To do this a private jet’s performance characteristics must allow it to take off and land from a wide variety of airports

Besides the above features that any successful private jet must have, the final product will have a few additional benefits. NASA’s N+2 criteria stipulate a 40 percent reduction in fuel burn. Lower fuel consumption will automatically lead to lower operating costs. Besides the reduction in operating costs, the final product will provide a quiet and efficient way to travel. Reduced fuel consumption on an aircraft that is also quiet and reliable meets both NASA’s N+2 criteria, and complies with the mission statement.

Page 4

SRR Endeavour 11 Feb 2010Although the jet will be capable of completing a wide variety of missions, it will be

designed for one specific mission. The group believes the most common use for the product will be to transport business executives. The typical trip length will be between 800 and 1000 nautical miles, and the jet will need to cover these distances at a speed of about Mach .85.

o Market

Before any major design took place, our group first wanted to know what potential market our final product would serve. Our group already had a good idea who would be buying the aircraft, primarily private businesses and fractional jet ownership companies. While who would be buying it was known, in what quantity was not so clear. Rolls-Royce released a forecast for the private jet industry in 2009. In this forecast it was estimated that 20,921 business jet deliveries would take place between the years of 2019 and 2028. This figure scales down to 11,600 private jet deliveries between 2020 and 2025. The group believes that if all of the goals set forth in the mission statement are met, then our aircraft will be able to capture a 5 percent market share. To be conservative the group set the mark at a 3 percent market share. This corresponds to 350 of the group’s aircraft being delivered between 2020 and 2025.

Page 5


Competitors

Table 2 : Customers

Airplane Customers

Cessna 680 Citation Sovereign Swift Air (Phoenix, AZ), Net Jet w/ Executive Jet Aviation

Cessna 750 Citation XWallan Aviation (Saudi Arabia, Dubai), Net Jets, PMCT Aviation, private owners (e.g. Arnold Palmer).

Dassault Falcon 2000 Hinduja Group (India), Executive Jet

Dassault Falcon 50, 50EXStephens Group LLC (Arkansas), adopted by France, Iraq, Iran, Italy, South Africa, Spain, etc. governments

Gulfstream 350/450Speed Jet Chartered Ltd. (Hong Kong), Middle East fractional operator National Air

Hawker 1000J. C. Bamford Excavators Ltd (UK), The Yeates Group (UK), United Technologies (U.S.), Aravco Ltd (UK), Executive Jet Inc/Net Jets (Columbus, Ohio)

Hawker 4000 Net Jet, BJETS (India)

Cessna 680 Citation Sovereign Swift Air (Phoenix, AZ), Net Jet w/ Executive Jet Aviation

Another aspect of the market that had to be considered before the actual design began was the competition. The group’s environmentally sensitive jet would not only face competition from the numerous other private jet manufacturers, but also from several other areas. Many private jet manufacturers exist, however, a certain few serve as our prominent competition. The following table shows the groups primary competition from within the private jet market:

Page 6


Table 3 : Market Benchmarks

Plane Units Market Cost per Unit

Bombardier Challenger 300 245 delivered USD 20.97 mil, typically equipped

Bombardier Challenger 600 series 795 delivered USD 28.08 mil, typically equipped

Cessna 680 Citation Sovereign 287 delivered USD 17.469 mil, typically equipped

Cessna 750 Citation X 301 delivered USD 21.721 mil, typically equipped

Cessna Citation series 225 expected to sell in 2010

Dassault Falcon 2000 417 produced USD 28.55-30.765 mil (2000DX, 2000LX)

Dassault Falcon 50, 50EX 352 delivered USD 20.6 mil (yr. 2004)

Gulfstream 350/450 170 delivered USD 31.955 mil (G350), USD 36.955 mil (G450)

Hawker 4000 130 ordered USD 21.671 mil, typically equipped

A seen in the above figure, Bombardier, Cessna, Dassault, Gulfstream, and Hawker will provide the main competition from private jet companies. Also listed above are the amount of units delivered and the price to buy a specific business jet. This data tells the group that the estimate of 350 aircraft deliveries is within the realm of possibility, and it also gives the group an initial idea of how much the final product will sell for.

Besides competition from other business jet manufacturers, a few other forms exist. A form of competition that could arise would be forms of high speed public such as bullet trains. Bullet trains are not yet wide spread, but by 2025, they could be. The commercial aviation industry could become a competitor if it could somehow change its operations to match the comfort and convenience of business jets, but it does not seem like that will happen. Any other competition would likely come from some form of transportation not yet seen, and therefore at this time the group cannot account for it.

Concept of Operations (CONOPS)

Page 7


o Customer Requirement & Solutiono Aircraft Payload & Passenger Capacityo Cabin Layout

By benchmarking the draft design concept of the new airplane against existing aircraft, the general volume and weight of the airplane was established. The methodology and code for finding these values are located in the Sizing Code section. With this in mind, it was then decided that the allowable cabin space for the airplane was to be as close to the following;

Available standing space at the highest point: 6.5 ft Cabin length: 25 ft. Cabin width: 7.5 ft.

As a professional business jet, the number of expected passengers falls within the range of 6-10 people. Below in figure 3 is a possible floor plan of the cabin layout. The lavatory location and exit locations are non-negotiable, but any other aspect of the system is changeable.

Figure 1 : 9 Passenger Configurations

Page 8

SRR Endeavour 11 Feb 2010In order to remain competitive in the upscale personal jet market, ample space;

standing room; and comfort were at the forefront of our sellable assets. However, a large part of the business model was written to included economical features, among which was high passenger volume. Logically, larger number of individuals in one aircraft detracts from the available space, standing room and overall comfort. To relate the luxurious and the economical situations, customizable interiors were indispensible.

To maximize the benefits of customizable space, a sketch of the empty floor plan made with the intention of filling the cabin with requested requirements. Visualizing this area in the airplane cabin helped provide specifications of the available internal floor space. The cabin was then limited by the total weight of the airplane. By changing only the interior layout of furniture within the cabin, the potentially expensive modifications to the airplane body and shape were then reduced. This then meant that only one airplane exterior had to be developed and the internal features could be modified to accommodate a nearly limitless number of layout designs.

To establish available space, the weight of specific interior items and their weight and required floor space were listed. Each seat is designed to carry an individual of 225 lb. For specifications of this number, see the Sizing Code section to what 225 lb. pertains to.

As a design consideration, one safety aspect that was considered was the location of an emergency exit. Though the cabin of the plane will only be 25 ft long, there are many instances when an accident could block or hinder the main cabin door. A simple way to prepare for this problem, an emergency door was considered. As it stands, the emergency exit is located 5 ft from the rear of the cabin (in front of the furthest most seat of the cabin before the lavatory) or a little further than 15 ft from the primary cabin exit. The exit is located on the opposite side of the plane to help prepare for any hazardous conditions that might block the original exit.

Since the exit is a part of the overall design, it will be immobile. Inasmuch, there will be a section of the customizable interior that must remain clear of obstacles. This design consideration is non-negotiable. In the image on the following page (figure 4), both main cabin door and emergency door can be seen in the model.

Page 9


Figure 2 : Isometric Interior Layout

Lavatories and galleys are an often over-looked aspect of an airplane cabin design. For long trips, both are relatively indispensable. When considering sizing, however, both are fairly difficult to fit in. The design of the airplane has a lavatory in the rear of the cabin. The lavatory seat then can be used as an auxiliary seat if needs.

A galley, (not included in the example on figure 3) would be most likely fitted nearer the front of the aircraft and draw power from sources near the cockpit power sources. This, however, would be flexible and could possibly be replaced by an in-flight bar depending on the customers’ personal preference.

o Design Mission

Basic criteria for design were based on the N+2 criteria from NASA, in which the primary obstacle toward development is the reduction of fuel consumption by 40%. In order to satisfy the customers’ needs, additional criteria were set; these included safety margins, large cabin area, lower operating cost, long range, low emissions, low noise engine, and comparable speed to in-class turbofan platforms. A large amount of legroom was incorporated when designing the

Page 10

SRR Endeavour 11 Feb 2010cabin layout. For safety reasons, a large wing aspect ratio with good gliding capability was considered. Maximum range was set to 3700 nautical miles which enables direct long-range transatlantic travels such as London-New York while catering to shorter runway constraints offering convenient and quick departures from smaller airports. The group aimed for these two locations in particular because market research suggested that one of the most important and frequent flights was between where the two biggest financial centers of the world, and where the largest corporate headquarters are located.

The new aircraft is designed for 1 pilot, 1 co-pilot, and 8 to 12 passengers depending on the customer’s needs.

Figure 3 : Typical Mission & Design Mission Specifications

Because not all flights are going to be at maximum range, the typical mission range was expected to be 1000 nautical miles. With the trip being shorter than the maximum range, the aircraft will be able to cruise at the maximum velocity. Most major cities were considered for typical mission range, though it is expected, due to the aircraft’s size and ability to take off from shorter runways, that generally smaller airports will be utilized by most customers. A thousand nautical miles is designed to cover short flights such as Chicago-New York, all of Europe, eastern Asia, and the greater Middle East. Also, because of long max range capability, typical mission range was not a limitation.

Page 11

SRR Endeavour 11 Feb 2010With shorter field length required for take-off and landing, most of smaller airports that

require shorter time for taxi and terminal will be approachable. However, because of shorter take-off and landing capability, aircraft’s performance was limited when elevations of the airports were high. More explanation for limiting factors is discussed in constraint diagram section.

Figure 4 : Mission Sketch

Mission profile is depicted above. After taxi and takeoff, aircraft will climb up to a service ceiling of 45000 feet. At this altitude, it will fly a typical range of 1000 nautical miles at cruising speed of 0.8M, maximum range of 37000 nautical miles at a slightly slower than cruising speed for optimal fuel consumption. Upon arriving destination airspace, the first attempt to land will be performed. In case of failure to land at the primary airport due to various reasons such as busy traffic or hazardous weather conditions, aircraft will climb clear of other air traffic. Extra range to secondary destination of 200 nautical miles has been added when calculating maximum range of the aircraft.

Fuel Fraction was initially calculated using a modified sizing code provided by Professor

Crossley. Cruising fuel fractionW 3

W 1 was calculated for maximum range trip. Despite historical

estimates, more precise calculation, taking into account the specific characteristics of the aircraft, will be necessary to define fuel consumption and weight.

Page 12


o Typical Operating Mission

The group designed the flight to operate between major economic cities regardless of the distance. Object was to be able to fly within a continent because of the size and speed of the aircraft. The threshold range is 3215.21 nautical miles. This range is suited to cover a non-stop transatlantic flight from New York - Paris or New York - London. Because the range is outside of the operating mission, a stop would be required to fly from New York to any city in Asia.

The flight time from New York to London is approximately 6 hours. The aircraft can take-off at the maximum twice daily because of the reduced transit time in the airport. Saving unnecessary time from transition allows the customers to take care of the customers’ business and fly back to their destination.

Table 4 : General airport Information

The table shown above is general information about the airport that is covered in the operating mission. The cities listed above such as Chicago, New York, Seoul and Paris is the economic center of the world. It is expected that the customers would use the business jet for business among those cities. Since the size of the aircraft is a mid-sized business jet, it is unnecessary and inefficient to operate in major airports such as O’Hare International Airport in Chicago or JFK in New York. Operating in these airports will delay much time in transition time, terminal time, and take-off or landing time. Because of this smaller airports that are around the

Page 13

SRR Endeavour 11 Feb 2010big cities above are recommended for operation. The table above lists the regional airports mainly for business flight but for the cities that do not have regional airports, secondary airport will be used instead.

Table 5 : Domestic Flight

Typical Mission ( ~ 652) Mid-Mission (652 ~ 2800) Maximum Mission (2800 ~ 3215) Unattainable Mission

The table above shows the flight distances between two domestic regional airports. Distances between New York-Chicago and Los Angeles-Las Vegas are well within our flight range. Also, even cities that are further apart are within our maximum range, enabling the aircraft to travel to anywhere within the U.S. from anywhere within the U.S. Specifically, New York City will be dealt with the main hub in USA, because it is the biggest economic city in the world. Moreover, it is the only city that the aircraft will be international flight or inter-Atlantic, to London.

Page 14

SRR Endeavour 11 Feb 2010Table 6 : Inter-Continental Flight

One of the world’s biggest economic countries, India, will have the main hub city, New Delhi, for flights across Asia. Geologically, departing from New Delhi will cover all cities in Asia operating in the typical and maximum mission. Also economically, India has a big market place that attracts many businessmen around the whole world. The mission of this aircraft is to transport the businessmen to well grown cities economically, not to transport people to develop cities that are not so big. In this sense, New Delhi satisfies operating missions geologically and economically.

For Europe countries, Paris will be a major hub city for within Europe flight. Like New Delhi, Paris satisfies all qualifications to be a main hub city. The figures below show the radius map from New Delhi and Paris.

Page 15


Figure 5 : Range Depictions

System Design Requirements

o QFD / House of Quality

With the open ended nature of the project, many of the design aspects were based off of general ideas about general ideas. All markets should have customer considerations at the forefront, but how each consideration would affect practical parameters could not be ignored. To weigh the importance of a particular customer request and a fundamental design aspect, a standard style QFD (or House of Quality) was used. The QFD measures customer desires (‘What’) against design items (‘How’). When deciding which customer desires were best matched for this QFD, the team categorized each ‘what aspect’ into four major areas listed below:

Performance Design Practical Comfort

‘Performance’ aspects included items in which a customer perceived as ‘good numbers’ for an aircraft. Under this category, high fuel efficiency, airport flexibility, airplane quickness, overall quietness and furthest distance covered were included.

Red – Maximum RangeGreen – Mid RangeBlue – Typical Range

Page 16

SRR Endeavour 11 Feb 2010The ‘design’ desires are based on the ascetic image of an aircraft. Although beauty is

only skin deep, it is still a large factor in any type of purchase. In this category, that ascetic ‘attractiveness’ was considered, as well as the project goal and increasingly-popular, economically-conscious ‘green image’.

‘Practical’ aspects of the customer desires include items that are more ‘business than pleasure’. Things considered include number of passengers, or power available. In which these items may be non-negotiable. For example, a very nice plane that can hold two people would not be practical for a trip that required eight or nine individuals.

When considering ‘comfort’, many liberties were taken. Comfort in an airplane often relates to space. In many cases, the more space the better. With this in mind, the idea of comfortable space was expanded to consider the following:

Personal spaceo Seat pitch o Seat width Standing freedom o Width of the isles o Largest space from the floor to the top arch of the aircraft Elbow room or working environmento Table availability o Table size

These items were compared to the design ‘Hows’, items that are design parameters with practical numbers and measurable units. The figure on the following page (Figure 8) is the result of the teams QFD. The salmon colored items are the major compliance requirements that need to be met according to the projected NASA N+2 criterion. An additional, expanded version of figure 8 can be found in the appendix section of the report.

Page 17


Figure 6 : House of Quality

o Benchmarks

Table 7 : Benchmarks

Plane Number of Seats

We

(lb)

W0

(lb)Mcruise

Max. Range with

Reserve (mi)

FAA Takeoff

Field Length (ft)

FAA Landing

Field Length

(ft)

Endeavour XG 8-12 19,800 32,000 .80 4,258 4,000 2,500Bombardier Challenger

300 11 23,500 38,850 .80 3,568 4,810 2,600

Cessna Citation Sovereign 9-12 17,720 30,300 472 mph 3,276 3,640 2,650

Cessna Citation X 8-12 21,700 36,100 552 mph 3,533 5,140 3,400

Page 18


Dassault Falcon 2000DX 8-19 22,360 41,000 .80 3,250 5,300 2,640

Gulfstream G250 10 23,750 39,600 .80 3,906 - -

Hawker 4000 8-10 22,800 39,500 .82 4,119 5,169 2,995

When designing an aircraft, it is important to have real world values to compare the design in progress to. In other terms, benchmarks are needed to see if the aircraft that is being designed is actually feasible. This process is called benchmarking. Table 7 shows the comparison of the design concept Endeavour XG aircraft to similar aircraft in size and specifications. As seen in the figure, the Endeavour XG is in the same class as the other aircraft with the number of seats and cruise Mach. Where the design concept aircraft sets itself apart is in the other specifications. It has nearly the lowest empty weight at 19,800 lbs and nearly the lowest overall weight at 32,000 lbs. The Cessna Citation X has the lowest empty weight at 17,720 lbs and the lowest overall weight at 30,300 lbs. This is a good comparison as one of the overall goals is to save fuel consumption and having a low weight will aid in this. Where the Endeavour XG sets itself apart is the maximum range that it can travel with reserve. It has a range of 4,258 miles still air. The closest comparison to this is the Hawker 4000 with a range of 4,119 miles. The range of the Endeavour XG allows many different airports to be reached without needing to stop as much. The FAA takeoff field length and landing field length are in the same class as the other airplanes that were examined which is a good measurement for the Endeavour XG. The data gathered was taken from Aviation Week & Space Technology 2009 Aerospace Source Book.

Figure 1 illustrates the technological goals from the NASA Subsonic Fixed Wing Project. These were developed in light of harm being caused to the environment from pollution and other various things. These future goals are to reduce carbon and nitrous oxide emissions along with reducing the noise impact near airports large and small. The goal of the Endeavour XG is to meet all standards set for the N+2 section with a launch date of 2020. This is very important to the nature of the aircraft being designed. Even though the initial concept doesn’t stray much away from current aircrafts in development, the main goal is to make the design concept more environmentally sensitive with less fuel burn and noise compared to the market. After examining several aircrafts, the Gulfstream G250 was chosen as the benchmark for the 40% fuel burn goal. Seeing as this aircraft is newly developed, this is a very ambitious goal to achieve. XG International understands this and the fact that achieving it will allow for the Endeavour XG to take over the market for business jets.

Page 19

SRR Endeavour 11 Feb 2010 Table 8 : Compliance Matrix

Table 8 is the compliance matrix completed by XG International. The NASA Subsonic Fixed Wing goals are bolded. Also, the right column shows if the design concept is compliant to the determined threshold values. As seen above, most of the determined requirements have been met with a few of them that are not compliant yet. The takeoff distance in feet is still an issue along with the noise generated in decibels. Lastly, the NOX emissions have not been satisfied. The biggest concern currently is the satisfaction of the noise and NOX emissions as these requirements correspond directly to the goal of the design concept. The takeoff distance will be altered as the concept is developed based on the length of airports that the aircraft will land at. Also, these measurements are difficult to determine without anything actually being built which is why most of the data is based from history.

Future Technology

Integrating advanced concepts is assuredly a vital step toward realizing our goals for sustained in-class performance despite drastic cuts in emissions, noise, takeoff ground roll, and fuel consumption. We plan to meet or exceed all of NASAs N+2 guidelines upon delivery in 2020 through a combination of proven and experimental technologies.

Page 20

SRR Endeavour 11 Feb 2010Recognizing that the number one constraint on performance and fuel consumption is

the choice of engine, but not wanting to sacrifice speed by designing a turboprop-driven vehicle, we are looking to GE to resurrect its GE36 propfan concept. Borne out of constraints on fuel consumption during the oil scares of the 70s and 80s, GE demonstrated proof-of-concept in the propfan, meeting its projections of 35% fuel savings over its turbofan contemporaries. We believe that this figure represents a conservative estimate of the capability of the engine, and plan on working closely with GE to fuel further research into the concept.

Figure 7 : Propfan Internal Mechanisms

The propfan is essentially a modified turbofan engine, combining the internal workings of a turbofan with a gear-reduced prop connected directly to the compressor-turbine shaft. The number one issue associated with the engine is cabin noise, but through the use of an Active Vibration Control System placed on the engine mounts, we believe that issue is not only solvable, but can be made compliant with the N+2 guideline for a 42 decibel reduction from similar turbofan platforms. The GE36 is production-ready, but it is more likely a derivative of the concept would be custom-fitted for the XG, allowing further research and ensuring smooth and quiet operation when integrated with the vehicle.

Active Vibration Control works much in the same way as a pair of noise-cancelling headphones, producing destructive interference which eliminates oscillatory motion at a range of frequencies. Structurally, the joints of the engine mounts through which noise and vibration would be transferred to the cabin would be fitted with the AVC system, significantly dampening vibration throughout the entire cabin or completely eliminating it in a smaller zone. The entire system is easily operated and adjusted by the flight crew. The Sikorsky S-92 helicopter employs a version of the system which eliminates ripples in a glass of wine during sustained cruise.

Page 21


Figure 8 : Active Vibration Control System

Rapidly declining in price while at the same time setting performance records in terms of its energy conversion abilities, solar film is a concept we plan on extensively investigating for integration with the XG platform. Being lightweight, flexible, and compatible with aircraft operations as demonstrated in the Solar Flyer and Helios concept craft, we believe it is possible to reduce fuel consumption while at the same time powering all the internal systems throughout the aircraft solely with solar energy. Conservatively assuming 40% of our wing area could be covered with current-generation solar films, the XG could be expected to generate 30 watts per square foot, which, stored via lithium-ion batteries, would be more than enough to power lighting, avionics, control surfaces, and high-tech devices on the aircraft, not to mention the possibility of completely severing the thrust system from internal power.

Page 22


Figure 9: Solar film

To reduce take off distance and improve the overall lift characteristics of the aircraft, a number of high lift devices are under consideration for integration with the XG. Additional innovative concepts we are looking into include aerodynamic technologies, in an effort to reduce the fuel needed to get our aircraft to perform at the level we intend. One scheme is to use blown-flaps, a high-lift device first developed in 1956 by the National Advisory Committee for Aeronautics. Though blown-flaps have been somewhat neglected since their invention, they are working their way back into the aircraft design neighborhood. As oncoming airflow hits the wing during flight, part of it rises above the airfoil and part of it goes below. The high velocity air travelling over the upper surface then proceeds toward the airfoil’s trailing edge, and meets the downward-deflected flap. At this point, the air stream splits up again. This time part of the flow seeps through the slot where the blown-flap is attached to the airfoil. It then smoothly rides along the rounded backside of the airfoil in laminar fashion to generate lift via the Coandă effect. The rest of the current also contributes to lift by continuing to flow downward along the blown-flap, which has a sharp trailing edge (Kutta condition). It can only be bent so much, however, before separation occurs. While this scheme significantly increases the lift coefficient, the main disadvantage is maintenance costs. This can be countered by keeping the angles at which the flaps are bent small. Though this would sacrifice some of the gained lift, the system’s contribution is still nothing to sneer at, especially during takeoff and landing. Our business jet’s design mold has not yet been determined, but if engines are placed above the wing and blown flaps are used (even at lowly bent angles), there would be considerable lift input.

Page 23


Figure 10 : High lift Devices

Another concept under consideration for incorporation into the Endeavour concept is vortex generators. These small triangular or rectangular vanes are built atop the front portion of a wing to delay flow separation and aerodynamic stall. They are very popular in several modern aircraft designs including the Gulfstream G150, a similarly-sized platform to the Endeavour. Vortex generators create vortices at the leading edge of the wing, which draws high-velocity air towards the boundary layer and thus adding energy to it. As a result, the effectiveness of trailing-edge control surfaces is increased. For our purposes, they help even more by increasing maximum takeoff weight, or reducing the adverse affects of weight. Max takeoff weight for small planes, like our 8-10 passenger business jet, is largely determined by the aerodynamic properties of the wings and fuselage, and delaying flow separation would increase the lift characteristics of the airfoil, enabling shorter takeoffs and landings by maintaining a larger CLmax.

Page 24


Figure 11 : Vortex Generators on the Gulfstream G150

Of special interest to the XG concept is the reduction of harmful emissions into the upper atmosphere, where they take longer to decompose and whose effect on climate change is palpable. To meet NASA’s N+2 goal of a 75% reduction in NOX emissions resulting from incomplete combustion, we plan on integrating an experimental concept known as Selective Catalytic Reduction. The idea has been explored most heavily in the automotive industry, but is simple in concept and execution, and easily extendable to aircraft platforms. The process works by injecting into the fuel mixture an additive which, when put in the presence of a catalyst medium, placed behind the combustor portion of the engine, breaks the NOX molecules into its constituent parts, N2 and H20. The concept has been shown to produce up to a 90% reduction in NOX emissions, with byproducts of C02 and NH4. The primary obstacle to integration in automotive or aircraft systems is the need for the fuel additive, which would need to be periodically refilled and adds weight to the craft.

Page 25


Figure 12 : Selective Catalytic Reduction Process

Figure 13 : Boeing 787 Composite Fuselage

Currently, the Boeing 787 represents the cutting edge in blended composite integration throughout the airframe, fuselage and wing platforms. Composite construction has a number of benefits over the aircraft aluminum standard in both weight and strength characteristics,

Page 26

SRR Endeavour 11 Feb 2010though it is somewhat more difficult to maintain and repair. A close-up of the interior fuselage wall reveals the intricacy of the single-body construction, which, while it eliminates the need for rivets or fasteners throughout the section, causes issues in its manufacturing complexity and transport. The manufacture of a large portion of both the fuselage and tail sections of the XG will enable a weight reduction of up to 20%1 increasing range and reducing both fuel consumption and takeoff distance while pushing the XG platform closer to the N+2 goals before its 2020 launch.

Initial Sizing

o Sizing Codeo Constraint Diagramo Estimated Values

The constraint diagram will limit the group’s aircraft with various limiting factors. Thrust to weight ratio at sea level, TSL/W0 and wing loading, W0/S can be found at top of the climb, subsonic 2g maneuver, takeoff ground roll, landing ground roll, and second segment climb. In order to create correct plots, it is important to know the correct variables. For top of the climb, the plot is based on Mach number and height of service ceiling. For subsonic 2g maneuver, the plot is based on the speed and the height. Takeoff ground roll plot is based on takeoff distance, height and hot day temperature, while landing ground off plot is based on landing distance, height and hot day temperature. Finally, second segment climb can be found from height and hot day temperature. The figure below is constraint diagram for Endeavour XG.

Page 27


Figure 14 : Constraint Diagram for Endeavour XG

The shaded region above is the area that has reasonable values of wing loading and thrust to weight ratio. Thrust-to-weight ratio of 0.33 was chosen for the Endeavour XG and

wing loading of 88 lbft2

. The reason why this area was chosen was the region had to be located

above the top of the climb, subsonic 2g maneuver, takeoff ground roll, landing ground roll and second segment climb gradient at given values, which means that the thrust to weight ratio has to be located at the top of all the plots. However, it is important to have smallest wing loading as possible because as wing loading gets smaller, the wing area that can hold the aircraft weight increases. Also, the larger value of thrust to weight ratio the aircraft has at sea level, the better the thrust. Overall, it is crucial to compromise the wing loading and trust to weight ratio based on the plots. The values that were stated above were found based on these reasons.

The next step that was done in order to obtain a reasonable weight was to set few variables to desired numbers. The aspect ratio, AR, of the aircraft was set to 9, which was similar to the benchmark aircraft Gulfstream G250. The passenger capacity was set to 8, and the number of crews was set to be 2, taking account for the pilot and the co-pilot. It was assumed that the weight of passenger including the baggage is 225 lb for a total weight of 1800 lb for 8 passengers. Also, the weight of one crew member was assumed to be 225 lb for a total

Page 28

SRR Endeavour 11 Feb 2010of 450lb. The design mission was set to 3700 nautical miles, and the alternate airport range was set to 200 nautical miles. Based on the constraint diagram, thrust to weight ratio at sea level

and wing loading were estimated to be 0.3 and 88 lbft2

, respectively. The max Mach number,

Mmax, was set to 0.84, and the cruise Mach number, Mcruise, was set to be 0.8. Specific Fuel Consumption during cruise, SFCcruise, was set to be 0.5 (1/hr), and Specific Fuel Consumption during loiter, SFCloiter, was set to be 0.4 (1/hr), which were based on the other jets that are similar to Endeavour XG.

Table 9 : Historical SFC Data

Also, based on the Aspect Ratio, maximum lift over drag ratio (L/D)max and lift over drag ratio at loiter (L/D)loiter was found using the equation below.

¿

Equation 1

( LD

)cruise

=0 .87∗AR

Equation 2

As a result, max lift over drag ratio and lift over drag ratio at loiter was found to be 19.7 and lift over drag ratio during cruise was found to be 17.14.

After the initial values were set, historical data was gathered through various media such as the manufacturer’s websites, Jane’s All the World’s Aircraft, Aviation Week, etc. Aircrafts that were concerned for were business aircrafts that are in service today with range of 3500 to 4000 nautical miles with 6 to 12 passengers. For each of the data that was taken,

various values such as Wo, W e

W o, We, AR,

T SLW o

, W o

S, Mmax, and Range were researched. Table below

shows the data that were obtained. It was very difficult to obtain data with reasonable correlation because even with a small difference in the correlation the final value of the empty

Page 29

SRR Endeavour 11 Feb 2010weight fraction changed. This is why only 11 business aircrafts were considered among 20 aircrafts that were chosen to be compared at the beginning.

Table 10 : Benchmark Characteristics

Wo[lb] We/Wo We[lb] AR TSL/Wo Wo/S Mmax Range[nmi]

G200 38,400 0.503 19,350 9.4 0.315 96.07 0.85 3400G250 38,700 0.519 20,100 8.0 0.351 80.00 0.85 3400Challenger 850 51,000 0.506 25,800 8.25 0.361 90.27 0.85 2811Learjet 60XR 23,500 0.625 14,681 7.2 0.392 88.85 0.81 2338Learjet 85 33,500 0.629 21,100 9.42 0.363 83.54 0.82 3000Citation x 36,100 0.599 21,625 7.8 0.374 68.5 0.92 3070Citation Sovereign

30,300 0.576 17,460 7.7 0.380 58.73 0.8 2881

Hawker 750 27,000 0.6 16,200 7.1 0.352 72.19 0.8 2100Hawker 850XP 28,000 0.583 16,330 7.7 0.333 74.86 0.8 2598Hawker 900XP 28,000 0.586 16,420 7.7 0.339 73.49 0.8 2850Hawker 4000 39,500 0.577 22800 7.2 0.349 73.39 0.84 3208

In order to calculate the accurate empty weight fraction of the group’s aircraft, the following equation was used.

W e

W o=b (W o )

C1 (AR )C2(T SLW o)C3(W o

S )C4

(Mmax )C5

Equation 3

Each of the coefficients signifies the correlation of the variable and the empty weight fraction. If the gross weight of the aircraft increases, the empty weight fraction will increase. Therefore, C1 had to be negative, regardless of the magnitude. If the aspect ratio increases, the empty weight will increase, eventually increasing the empty weight fraction. Therefore, C2 had to be positive. If the thrust-to-weight ratio increases, it will be good for the airplane because this means that the aircraft will have more thrust per a certain unit of the weight. Therefore, C3

had to be positive. Increasing the wing loading is not good for the empty weight fraction because the aircraft is heavier compared to a certain number of wing area, so C4 had to be negative. If the max Mach number increases, it signifies the fact that the aircraft is lighter, therefore C5 had to be positive. To obtain the coefficients, MATLAB was used using least

Page 30

SRR Endeavour 11 Feb 2010regression curve fit for the natural log values of the data. The equation to obtain the coefficient is as follows:

X=f∗a+e

Equation 4

Where vector X is a column vector of all lnW e

W o values, f is a matrix of the values listed in the

table above, a is a matrix of the coefficients to be obtained, and e is a matrix of error of the least regression curve fit. To specifically obtain “X \ f” was used. This command output a vector a with the least error possible. Table below shows the coefficients that were obtained.

Table 11 : Coefficients

ln(b) C1 C2 C3 C4 C5

2.2627 -0.3083 0.2658 0.0138 -0.0025 0.6114

As it can be seen in the table, the signs of the values that were obtained for the group matches the signs of the values that should outcome to. These values were then put into the initial sizing code provided by Professor Crossley. The group’s final value came out to be

W e

W o=0.615089

Equation 5

This value is in the higher section among its class of 11 business aircrafts that were

researched. The only two aircrafts that exceeded the group’s W e

W o value was Bombardier Learjet

60XR and Learjet 85. However, these two aircrafts had significantly lower range than the group’s aircraft.

Before the first presentation, this value was about 0.58. This difference was due to the miscalculation of the average weight of the crews and passengers. The group had first predicted that the average weight of one passenger was 220 (lbs) with baggage and 200 (lbs) for one crew. However, people from Gulfstream had suggested that this weight estimation had changed from 220 lbs/ passenger and 200 lbs/ crew to 225 lbs/ passenger and crew. Changing this value increased the empty weight fraction by a considerable amount.

Page 31

SRR Endeavour 11 Feb 2010Technology factor of 0.95 was factored in the empty weight fraction. The technologies

that were considered were solar films, propfan engine, vortex generators, and high-lift devices. These technologies will be explained in more detail later on.

To obtain the values We, Wf, and Wo, the following equations were used.

W f=W f

W o∗W oguess

Equation 6

W e=W e

W o∗W oguess

Equation 7

W o=W f+W e+W passenger+W crew

Equation 8

where Wf is the fuel weight of the aircraft, We is the empty weight of the aircraft, and Wo is the gross weight of the aircraft. The weights are shown in table 12.

Table 12 : Weights

We[lb] Wf[lb] Wo[lb]

19800 10100 32000

Page 32


Summary

For this project the group was asked to design a business jet that was capable of meeting NASA’s N+2 criteria. In order to meet these criteria, the final product would have to very environmentally sensitive. The challenge of completing this project successfully lies how to design a business jet to be environmentally sensitive, and at the same time not lose any performance compared to current business jets.

The product will be designed with a very specific mission in mind; however a wide variety of missions will be in the realm of possibility for the group’s aircraft. The specific mission is one that simulates the typical trip of a business executive. This particular trip was defined by the team as one that was approximately 800 to 1000 nautical miles in length, and required speeds up to Mach .82. When not limited to this mission, the aircraft will have a maximum range of 3700 nautical miles, and a maximum cruise speed of Mach .82. While the typical mission will carry only one or two passengers, the aircraft will have a maximum capacity of 8 passengers. While the aircraft must be capable of completing the above missions, it must also be environmentally sensitive. The team’s aircraft will be environmentally sensitive in several ways, from noise reduction and lower fuel consumption to fewer harmful emissions.

Once the final product is complete, the team will be marketing it to a few very specific groups of people. The first is the group of fractional jet ownership firms. These businesses buy private jets and lease them to people. Besides these leasing companies, private businesses will also be targeted. It is very common for companies to send their executives around the globe on private jets for meetings and other business tasks. The team plans to capitalize on this market heavily, because the final product will be ideal for private business needs.

In order to get an initial estimate of how many aircraft the group will be able to sell, a Rolls-Royce forecast was utilized. Using this forecast the group predicted 350 aircraft deliveries between 2020 and 2025, and a total of 600 before 2031. If the group successfully completes the design to all previously mentioned specifications and delivers as many aircraft as expected, this will be a very profitable venture.

To meet all of NASA’s N+2 criteria and achieve all performance goals several advanced concepts will be utilized in the design. The group is not exactly sure what technologies will be used at this point, however several are under consideration. First, the group is going to look at hybrid power systems, such as solar cells, to provide auxiliary power for the aircraft. Also under consideration are some advanced aerodynamics concepts to reduce

Page 33

SRR Endeavour 11 Feb 2010fuel consumption and increase mission flexibility. Other advanced concepts will be considered as the design progresses.

The group now has a clear definition of the design mission, typical customer, and potential market capitalization. Ideas and concepts that will be used to meet NASA’s N+2 criteria have also been formalized. The group feels very confident going forward with the design, and hopefully the final product will serve as a platform to achieve NASA’s N+3 guidelines in the future.

The Next Step

For the next step, XG will demonstrate the ability to meet the performance targets and customer requirements through benchmarking and various proof-of-concept tests. Also, possible configurations and technologies must be further explored. Some of these technologies include choosing and locating the engines and the wings to the suitable place. For the engines, the group will consider GE 36 as the future engine, which is the combination of propfan (at the back) and turbojet (at the front). This will increase the efficiency, which will have great impact on group’s 40% fuel reduction mission. However, the noise has become the problem. Endeavour XG has to compromise this problem to reach the group’s goal and satisfy the customers. Then the group will analyze effects and tradeoffs for integrated systems. Later on, the group will redefine the QFD, compliance matrix, sizing code and the 3-D model. Sizing code will be developed by MATLAB and 3-D model will be done by CATIA. Finally, aerodynamics of Endeavour XG, which will have a big impact on the group’s ability to meet all the customers’ needs, will be analyzed.

Page 34


Reference

1. 2010 Port of Bremerton. Brementon, Jan. 2010. Web. <http://www.portofbremerton.org/>

2. Acoustic pressures on a prop-fan aircraft fuselage surface (1980): 11+. Print.

3. Air Toxic from Motor Vehicles. Air Quality Where You Live. Web. <www.epa.gov>.

4. Aviation Week & Space Technology 1 Feb. 2009. Print.

5. Crossley, William. "Aircraft Initial Sizing Excel File" Web.

6. Crossley, William. "Constraint Diagram Excel file. Web.

7. Crossley, William. "In-Class QFD example" Web.

8. ELM Pass Plus. Elmira Corning Regional Airport, 2007. Web. 11 Feb. 2010. <http://www.ecairport.com/>.

9. Fort Lauderdale-Hollywood Airport. Broward County. Web. <http://www.broward.org/airport/>.

10. "Free Maps Tools." Free Maps Tools. Google. Web.<http://www.freemaptools.com/radius-around-point.htm>.

11. Great Circle Mapper. Karl Swartz. Web. <http://gc.kls2.com/>.

12. London Biggin Hill Airport. London Biggin Hill Airport. Web. <http://www.bigginhillairport.com/>.

13. London City Airport. London Airport Ltd. Web. <http://www.londoncityairport.com/>.

Page 35


14. Propfan Engines. Aerospace Web Organization, 24 Feb. 2002. Web. 11 Feb. 2010. <http://www.aerospaceweb.org/question/propulsion/q0067.shtml>.

15. Sikorksy to test active vibration control for S-92 rotor hub. Flight International, 16 Feb. 2009. Web. 11 Feb. 2010. <http://www.flightglobal.com/articles/2009/02/16/322533/sikorksy-to-test-active-vibration-control-for-s-92-rotor.html>.

16. Understanding the Cost of Solar Energy. Green Econometrics, 13 Aug. 2007. Web. 11 Feb.

2010. <http://greenecon.net/understanding-the-cost-of-solar-energy/energy_ economics.html>

17. Waukegan Regional Airport. Waukegan Port District, 2002. Web. <http://www.waukeganport.com/wkgn_airport/>.

Page 36


Appendix

Page 37


Page 38


Page 39

engineering.purdue.edu · Web viewDevelop an environmentally-sensitive aircraft which will provide our customers with a 21st century transportation system that combines speed, comfort,

Documents