Title
The Daedalus One
Conceptual Design Review
Daedalus Aviation-Team 1
AAE 451-Spring 2008
April 24, 2008
Design Team
James Bearman
AJ Brinker
Dean Bryson
Brian Gershkoff
Kuo Guo
Joseph Henrich
Aaron Smith
Executive Summary
Daedalus Aviation is a conceptual design firm that is creating the aircraft of the future. This report is a full aircraft design concept, including aerodynamic analysis, structural design, configuration, dimensions, interior layout, propulsion choice, advanced technology selection, aircraft size, performance, and cost predictions.
To do this, Daedalus Aviation has taken the working design from the engineering definition report, analyzed, modified, and altered the design to generate the final aircraft presented in this document.
Deadalus One, the aircraft under development, is scheduled to be released for sale in the late 2030s and early 2040s. The intervening twenty to thirty years will see marked advances in aviation technology, and Daedalus Aviation will capitalize on technologies currently in development which are expected to be in mainstream use by 2040. These technologies range from artificial intelligence aircraft control to geared turbofans; from composite materials to blown flaps.
The Daedalus One is within acceptable range for all engineering requirements calculated by the specialized aircraft sizing program. According to the computer models used by Daedalus Aviation, the Daedalus One:
• Has a range of 1800 nautical miles
• Carries 108 passengers
• Can takeoff and land in 2500 feet
• Cruises at .75 M
Table of Contents
Executive Summary 2
1. Business Case 7
1.1 Mission Statement 7
1.2 Target Market 7
1.3 Example Use Case 8
2. System Requirements 9
2.1 Design Missions 9
2.1.1 Standard Cruise Mission 10
2.1.2 Short-Cruise Long-Cruise Mission 10
2.1.3 Spiral Approach Mission 11
2.2 Design Requirements and Justification 12
2.3 Current System Compliance 14
3. Concept and Configuration 15
3.1 Selected Concept 15
3.1.1 Walk-Around and Major Features 16
3.1.2 Cabin Layout 17
3.1.3 Major Dimensions 18
3.1.4 Ground Service Diagram 19
3.2 Major Design Trade-Offs 19
4. Advanced Technologies Integrated 20
4.1 Upper Surface Blowing 21
4.2 Composites 22
4.3 Geared Turbofans 23
4.4 Automated Pilot 24
4.5 Environmental Impact, Reliability, and Maintainability 24
5. Aircraft Sizing 25
5.1 Carpet Plot 25
5.2 Sizing 27
5.2.1 Sizing Software Summary 27
5.2.2 Mission Profile 27
5.2.3 Sizing Inputs and Results 28
6. Aerodynamic Analysis 31
6.1 Airfoils 31
6.2 High Lift 33
6.3 Drag Build Up 34
6.4 Drag Polars 36
7. Performance 37
7.1 Flight Envelope 37
7.2 V-n Diagram 38
7.3 Best Range and Endurance Velocities 39
7.4 Takeoff and Landing Parameters 40
8. Propulsion 42
8.1 Propulsion System Description 42
8.2 Thrust Available and Required 43
9. Structural Layout 45
10. Weights, Balance and Stability 48
10.1 Weight Group Breakdown 48
10.2 CG Position 49
10.3 Neutral Point and Static Margin 49
10.4 Canard and Elevator Sizing 50
10.5 Vertical Tail Sizing 51
11. Cost Analysis 53
12. Future Steps 56
References 57
Aircraft Order Form 58
Appendix 60
Table of Figures
Figure 1: Standard Cruise Mission 10
Figure 2: Short-Cruise Long-Cruise Mission 10
Figure 3: Spiral Approach Mission. 11
Figure 4: Daedalus One Multi-View 15
Figure 5: Daedalus One Walk-Around Diagram 16
Figure 6: Daedalus One Passenger Cabin 17
Figure 7: Dimensioned Side View 18
Figure 8: Dimensioned Top View 18
Figure 9: Ground Service Diagram 19
Figure 10: Examples of Blown Flaps [5] 21
Figure 11: Performance of Blown Flaps [5] 22
Figure 12: Decrease in SFC Over Time 24
Figure 13: Carpet Plot 26
Figure 14: Sizing Mission Profile 27
Figure 15: Comparison to Historical Range and Takeoff Weight 29
Figure 16: Comparison to Historical Takeoff Field Distances and Gross Takeoff Weight 30
Figure 17: Comparison to Historical Gross Takeoff Weights and Passenger Capacity 30
Figure 18: Main Airfoil NASA SC 20712 31
Figure 19: 2D Lift Curve Slope of SC 20712 32
Figure 20: NASA SC 20012 32
Figure 21: 2D Lift Curve Slope of SC 20012 33
Figure 22: Cruise Configuration Drag Polar 36
Figure 23: Takeoff and Landing Configuration Drag Polar 37
Figure 24: Flight Envelope 38
Figure 25: V-n Diagram 39
Figure 26: Demonstration of Best Range and Endurance Velocities 40
Figure 27: Thrust Available and Required at Cruise at 35,000 ft 43
Figure 28: Thrust Available and Required at Takeoff 44
Figure 29: Top View of Load Paths 45
Figure 30: Side View of Load Paths 46
Figure 31: Wing Load Paths 47
Figure 32: CG Diagram of Daedalus One 49
Figure 33: Aircraft Reference Free Body Diagram 52
Figure 34: Convergence History of Cd 60
Figure 35: Convergence History of Cl\ 60
Table of Tables
Table 1: Ranges and Runway Lengths for Use-Case 1 8
Table 2: Ranges and Runway Lengths for Use-Case 2 8
Table 3: Ranges and Runway Lengths for Use-Case 3 9
Table 4: Ranges and Runway Lengths for Use-Case 4 9
Table 5: Engineering Design Requirements 12
Table 6: Daedalus One System Compliance Matrix 14
Table 7: Engine Thrust and SFC Over Time 23
Table 8: Current Geared Turbofan Savings 25
Table 9: Sizing Inputs 28
Table 10: Sizing Outputs 29
Table 11: Load Factors 38
Table 12: Takeoff and Landing Parameters 41
Table 13: Structural Weight Breakdown 48
Table 14: Propulsion Weight Breakdown 48
Table 15: Equipment Weight Breakdown 48
Table 16: Summary of Cost Analysis 53
Table 17: Breakdown of Project Costs 53
Table 18: Summary of Operating Costs 54
Table 19: Description of Cost Variables 55
1. Business Case
1.1 Mission Statement
The goal of Daedalus Aviation is to provide a versatile aircraft with an acceptable range and reasonable passenger capacity to meet the needs of a commercial aircraft market still expanding in 2058. Daedalus Aviation will incorporate the latest technology into our aircraft so as to improve efficiency and reliability. This is particularly important when an environmentally friendly aircraft is demanded by not only the general public, but also by the airlines as well. The technologies that will most improve the versatility of the aircraft are the enabling technologies that allow the aircraft to have Extremely Short Take-Off and Landing (ESTOL) capability.
1.2 Target Market
Currently, flight routings are scheduled using what has been called the hub-and-spoke system, or a network in which all routes move along spokes connecting and radiating from centralized hubs. Using this system, the majority of passengers fly between major airports (such as Chicago O’Hare to Las Vegas McCarran), and those same major airports connect to smaller airports. The result of this is that the airlines can use large, high capacity airplanes to transport the majority of the people and smaller planes to do short hops to the secondary airports. For the passengers, this means that most destinations can be reached within one or two stops.
Unfortunately, in recent times the major hubs have been showing an alarming trend of overuse. This is a major problem because if there is a flight delay at a major hub, even for a single route, it could result in a cascade of inconveniences across the national network. In order for a hub to perform at an efficient level, air traffic must be timed perfectly, which is not always possible due to overcrowding from increased airline operations and the ever-present weather. In addition, the hubs are saturated and can not accommodate an increase in flight scheduling. Neglecting a significant change in hub capacity, airline schedule expansion will be limited.
Daedalus Aviation, with our flagship aircraft, the Daedalus One, aims to provide a possible solution to this problem. Daedalus One has been designed with the idea that the hub-and-spoke system will not be sustainable in the future, and as such, unable to alleviate the increasing demand. This will result in airlines being unable to provide a reasonable level of comfort to their passengers, and force them to extend service to nearby airports. This shifting trend has already begun and can be seen with the success and growth of “secondary” airports such as Dallas Love Field and Chicago Midway. The service at these “secondary” airports provides additional convenience for the passenger, who may be able to utilize an airport closer to their home or destination. This method will alleviate the burden on the hub airports themselves, and provide benefits to the airlines as well.
In anticipation of this shifting trend towards secondary airports, Daedalus Aviation designed our aircraft for Short Takeoff and Landing (STOL) or Extremely Short Takeoff and Landing (ESTOL). In addition to the increase of usable airports, STOL and ESTOL aircraft can be used to ease the pressure on major airports. An aircraft with these capabilities can allow the hub airports, who typically have the larger runways, to support multiple takeoffs and landings per runway, dramatically increasing the runway capacity of the airport. This ability assists in lowering the demand placed on the hubs.
Daedalus Aviation intends to provide the market with this capability while still maintaining the airline’s need for acceptable passenger capacity and range.
1.3 Example Use Case
The primary use case for the Daedalus One is a route that connects two major cities by airports other than their respective hubs. An example of this is a flight from Schaumburg, Illinois, to North Las Vegas Airport, Las Vegas, Nevada. This use-case utilizes the mission profile in Figure 1. Chicago to Las Vegas is one of the top ten domestic city pairs in the US in terms of number of passengers [1]. However, O’Hare and McCarran International Airports are two of the busiest, and therefore most delayed, airports in the country. The Daedalus One alleviates this market by opening up service using two smaller, less utilized airports as outlined in Table 1. This is representative of a regularly scheduled commercial route between two major metropolitan areas.
|Airport |Location |Range (nmi) |Runway Length (ft) |
|Schaumburg Regional (06C) |Schaumburg, IL |- |3800 |
|North Las Vegas (VGT) |Las Vegas, NV |1300 |4200 |
Table 1: Ranges and Runway Lengths for Use-Case 1
Another use-case that Daedalus One could fulfill using a long range mission profile is from South Bend, Indiana, to Burbank, California. It is a relatively long range route (slightly over the threshold range) and characterizes the most common usage for the aircraft. This could be representative of a chartered route for a football team with staff traveling to a rival college. This type of route maximizes convenience for the passenger by using small airports near their arriving and departing locations; in this case South Bend Regional is near Notre Dame University and Burbank Bob Hopeis the closest airfield to the University of Southern California as outline in Table 2. This is significantly more convenient to the passenger than a flight from Chicago O’Hare to LAX.
|Airport |Location |Range (nmi) |Runway Length (ft) |
|South Bend Regional (SBN) |South Bend, IN |1580 |4300 |
|Bob Hope Airport (BUR) |Burbank, CA | |5800 |
Table 2: Ranges and Runway Lengths for Use-Case 2
A variant of the South Bend-to-Burbank use-case involves making a stop at a small airport without refueling, utilizing the mission profile in Figure 2. An example of this would be a spring break charter originating at Purdue University in West Lafayette, Indiana, taking on additional passengers from University of Illinois Urbana-Champaign at Willard Airport, and then flying to the major international airport at the popular tourist destination, Cancun, Mexico, as outlined in Table 3. This type of mission increases the probability that the flight will be full (i.e. profitable) by drawing on multiple customer bases. It also provides for passenger convenience by using small, nearby airports. In the event that an intermediate airport does not have a readily available fuel supply, the Daedalus One would be able to make the stops between the origin and destination without refueling.
|Airport |Location |Range (nmi) |Runway Length (ft) |
|Purdue University Airport (LAF) |West Lafayette, IN |- |4225 |
|Univ. of Illinois-Willard (CMI) |Champaign/Urbana, IL |65 |3817 |
|Cancun International (CUN) |Cancun, Mexico |1140 |11483 |
Table 3: Ranges and Runway Lengths for Use-Case 3
A fourth representative city-pair that could be serviced by the Daedalus One is the common commercial route from Minneapolis St. Paul International Airport to Los Angeles International Airport, as outlined in Table 4. This use-case would use mission profile appearing in Figure 3. Flying this type of route demonstrates the ability of the Daedalus One to be effective in hub-to-hub operations. Using the simultaneous take-off and landing scheme described earlier, an aircraft could take off on the upwind portion of the runway in Minneapolis while a second ESTOL aircraft is landing on the downwind portion. The aircraft could then use the same scheme when landing in Los Angeles. Using this scheme, the Daedalus One improves efficiency and throughput at the major hubs by allowing two aircraft to use a single runway at once. This improvement is then passed down to the passengers in the form of shorter travel time and, ultimately, a better travel experience. By maintaining service at major hubs, the Daedalus One also allows passengers make connections to longer flights using larger, conventional aircraft.
|Airport |Location |Range (nmi) |Runway Length (ft) |
|Minneapolis-St. Paul Int’l (MSP) |Minneapolis, MN |- |½ of 8000 |
|Los Angeles International (LAX) |Los Angeles, CA |1330 |½ of 8925 |
Table 4: Ranges and Runway Lengths for Use-Case 4
2. System Requirements
2.1 Design Missions
The Daedalus One is designed to be capable of flying a variety of missions. The ESTOL capability allows it to service small, local airports, medium-sized feeder airports, and large hubs. Being able to utilize airports of all sizes helps the Daedalus One to meet the variety of needs of airlines and charter companies. Airlines would be able to expand point-to-point operations using smaller airports, provide service to hubs from a larger number of feeder airports, and avoid major hubs by routing through smaller airports near hubs. Additionally, charter airlines may be able to better serve their clients by utilizing small, local airports near the origin and destination.
2.1.1 Standard Cruise Mission
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Figure 1: Standard Cruise Mission
The first design mission is a standard cruise mission as shown in Figure 1. The mission begins with taxi and takeoff from a runway as short as 2,700 ft. The Daedalus One then climbs to altitude at the best rate of climb. A step cruise will be implemented to improve range over a constant-altitude cruise, also allowing the aircraft to clear weather and turbulence. At the end of a flight of up to 1800 nmi, the Daedalus One will descend and enter a holding pattern if directed by air traffic control. Upon being cleared to land, the Daedalus One will make its final approach, land, and taxi to the terminal. In the event of a missed approach, or inclement weather or other emergency at the destination airport, reserve fuel is allotted so that the Daedalus One may climb back to altitude, cruise to another airport up to 200 nmi away, hold as directed, and land.
2.1.2 Short-Cruise Long-Cruise Mission
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Figure 2: Short-Cruise Long-Cruise Mission
The second design mission incorporates a short flight followed by a longer flight as shown in Figure 2. As in the previous mission, the flight begins with taxi and takeoff from a 2,700 ft runway. The Daedalus One will climb to an altitude appropriate for its short-duration cruise (the altitude may be dependent on the length of the cruise). The aircraft will land on a short runway at a small airfield to deliver and take on passengers and other payload. The aircraft may refuel, but if fuel is not available or is cost prohibitive, the Daedalus One may takeoff again without refueling. The mission then proceeds as in the first mission, with a climb to altitude, step cruise, descent, hold, and landing at a small or large airport. This mission also includes reserve fuel for rerouting to another airport.
2.1.3 Spiral Approach Mission
[pic]
Figure 3: Spiral Approach Mission.
The third design mission, the spiral approach mission, is illustrated in Figure 3. This mission begins the same as the previous missions by taking off from a short runway, climbing to altitude, and then step-cruising to improve range. What makes this mission unique is the descent and approach at the destination airport. Instead of making a standard approach, the Daedalus One will make a non-interference spiral approach. This type of approach allows airports with multiple long (>8,000 ft) runways running parallel to each other to increase runway throughput. With the Daedalus One’s ESTOL capability, one aircraft can takeoff on the upwind portion of a long runway while another can land on the downwind portion. In the meantime, other aircraft can make conventional takeoffs and landings on a separate runway. This mission also includes reserve fuel so the aircraft can be rerouted to another airport.
2.2 Design Requirements and Justification
|Engineering Requirement |Condition |Target |Threshold |
|Takeoff Roll |≤ |2,500 ft |3,500 ft |
|Landing Roll |≤ |2,500 ft |3,500 ft |
|Takeoff Field OEI |≤ |4,000 ft |5,000 ft |
|Takeoff Weight |≤ |80,000 lb |100,000 lb |
|Range |≥ |1800 nm |1500 nm |
|Max Cruise Speed |≥ |0.85 M |0.75 M |
|Passenger Capacity |≥ |110 |90 |
|Payload Capacity |≥ |28,300 lb |23,300 lb |
|Fuel Burn |≤ |0.10 lbs/(pax-nm) |0.12 lbs/(pax-nm) |
Table 5: Engineering Design Requirements
Table 5 summarizes the engineering design requirements for the Daedalus One. These requirements were generated after a series of market and trade studies to identify the needs of the customer and projected deficiencies in the current fleet. By meeting these design requirements, the Daedalus One should be capable of meeting the needs of the future market.
The takeoff and landing ground rolls should be less than 2,500 ft, with the maximum allowable being 3,500 ft. Achieving a 2,500 ft ground roll would open access to over 90% of US airports, while a distance of 3,500 ft would only cut accessibility back to approximately 85% [2]. A takeoff balanced field length with one engine inoperative of 4,000 ft with a maximum allowable of 5,000 ft would allow access to small airfields, based on a small representative sampling [2].
The gross takeoff weight is not a typical design requirement. However Daedalus Aviation believes that this aspect is of high importance if the Daedalus One is to serve small airports. Small runways are typically not built to withstand the loads produced by large commercial aircraft. As a result, some of these runways may have ramp weight limits imposed on them. Limiting the gross takeoff weight allows the Daedalus One to service these airports with little or no runway improvement.
The target range for the Daedalus One is 1,800 nmi, with a minimum range of 1,500 nmi. Currently, approximately 85% of domestic flights and 80% of all flights with one city in the US travel a distance of 1,500 nmi or less, with only a small addition of flights for each additional 500 nmi [1] increasing point-to-point service and adding feeder routes from small airports, Daedalus Aviation expects the number of short distance flights to increase, and decided to target this range.
The cruise speed requirement was set to provide short flight times for travelers. A target of 0.85 M was set to meet or improve upon cruise speeds of the current fleet. A threshold of 0.75 M was set because reducing cruise speed to this level from 0.85 M would only add half an hour to flight time over a mission of 1,800 nmi. Increasing flight time beyond this was judged by Daedalus Aviation to be intolerable to passengers.
The passenger capacity of the Daedalus One was set to range between 90 and 110 passengers. This was based on an evaluation of the current global fleet by competitor Embraer [3]. One of the major findings was that the fleet in all global regions lack aircraft with capacities of 70-110 passengers. Daedalus Aviation plans to pursue this market by suppling aircraft with this passenger capacity. The payload capacity was also set to allow up to 250 lbs per passenger, plus the required crew.
The fuel burn requirement was defined so that the Daedalus One would not perform worse than current aircraft. If the Daedalus One had a worse fuel burn than other aircraft in a similar class, airlines may be hesitant to purchase the aircraft, even if it was superior to other aircraft in other ways. Thus, the fuel burn target is 0.10 lbs per seat-mile, and the threshold is 0.12 lbs per seat-mile, to improve upon current aircraft.
2.3 Current System Compliance
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Table 6: Daedalus One System Compliance Matrix
Table 6 shows the compliance of the Daedalus One with the design requirements. The targets for the takeoff roll, landing roll, range, and maximum cruise speed were met. For the rest of the requirements, the thresholds were exceeded. It is notable that the Daedalus One came close to meeting all of its targets, with all targets missed by less than 10%, with the exception of fuel burn, which was within 14% of target.
3. Concept and Configuration
3.1 Selected Concept
[pic]
Figure 4: Daedalus One Multi-View
Figure 4 depicts the final configuration of the Daedalus One. It features a low, swept wing design with a high-mounted canard. The engines are geared turbofans, which offer a better rate of fuel consumption than modern methods of propulsion. All composite construction was used over traditional aircraft metals. A single-tail design was opted over the previous tri-tail configuration.
Daedalus Aviation has experienced some difficulty during the CAD modeling. As a result of this, there are two changes which are not reflected in the model. The first is the engine size; the engine diameter is approximately half of what is called for in the design. The second is the empennage, the true design calls for a more conical section.
3.1.1 Walk-Around and Major Features
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Figure 5: Daedalus One Walk-Around Diagram
The Daedalus One utilizes a wide range of advanced technologies to effectively and efficiently accomplish the mission goals that are required. Since one of the main goals is the ability to use nearly any runway, Daedalus One uses upper surface blown flaps to increase lift during takeoff, allowing it to do so in a much shorter distance. Geared turbofan engines were chosen due to promising advances in their fuel efficiency and consumption. These will maintain a low environmental impact, and to keep operating costs relating to engine maintenance and fuel to a minimum. The lifting canard was also necessary to increase the lift, to provide rotation during takeoff, as well as provide stability during flight. In order to allow Daedalus One to fly at higher speeds and reach its destination in a much shorter period of time, a supercritical airfoil was chosen for the wing design. This allows it to fly at speeds that exceed that of today’s passenger aircraft. An all composite construction was chosen in favor of more traditional aircraft metals. This reduces cost by reducing weight, which is a major consideration of any aircraft. They are also much stronger than metals, which will keep maintenance costs related to structural repairs down. Finally, Daedalus One takes advantage of advancements in Artificial Intelligence (AI) technology and superior avionics to make control of the aircraft much easier. “Fly by light” fiber optic cables are utilized for an increase in the response time of the controls to operator input. The operator itself will be AI, which will not make mistakes or get tired like a human pilot would. In case of the unlikely event of a failure with the AI, a trained operator will be on board in order to take over the flight controls, as well as provide passenger assurance.
3.1.2 Cabin Layout
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Figure 6: Daedalus One Passenger Cabin
The interior of the Daedalus One was optimized with passenger comfort in mind. An extra row of seats was added from the last design iteration, increasing the maximum passenger capacity to 108 from 102. The following are the other important measures pertinent to the seating and facilities on board:
• Seat Pitch: 32 inches
• Seat Width: 20 inches
• Aisle Width: 24 inches
• 2 Galleys: 35 and 16 ft²
• 2 Lavatories, both approximately 20 ft²
• 4 Emergency Exits, located in the front and rear of the seating area
Another change from the last design iteration, aside from the added row of seats, was a decrease in seat width in order to accommodate a larger aisle width. This new seat size still allows ample seat width, while making movement throughout the cabin much easier for passengers and flight attendants.
3.1.3 Major Dimensions
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Figure 7: Dimensioned Side View
[pic]
Figure 8: Dimensioned Top View
Major dimensions of Daedalus One include:
• Canard Area: 300 ft²
• Wing Area: 722 ft²
• Tail Area: 310 ft²
• Wing Span: 100.5 ft
• Canard Span: 34.6 ft
• Fuselage Length (nose to tail): 97.6 ft
• Tail Height Above Ground: 33.7 ft
The above two figures show some of the more important dimensions related to the Daedalus One. The people standing next to the aircraft are 5 ft 10 in tall, which would be the height of an average person who might be doing any kind of maintenance on the Daedalus One. This shows that baggage handling and any ramp work done in between flights would be made much easier due to the fuselage’s proximity to the ground. Also, since the lower wing design makes the engines easier to access, any maintenance performed on them would be simplified.
3.1.4 Ground Service Diagram
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Figure 9: Ground Service Diagram
3.2 Major Design Trade-Offs
As it has been previously mentioned, a number of changes were made from the previous iteration of the Daedalus One to the current, finalized design. These changes were made for numerous reasons. The most visible change was the switch from a high wing/low canard to low wing/high canard configuration. The primary reason this was done was to allow this configuration’s landing gear to be much shorter than it would have been with the high wing. This reduces complications with the weight and storage of the gear. This configuration allows ground service a greater accessibility to the fuselage. In addition, the canard placement causes fewer complications with the jetway access, which is quite important for passenger entrance and egress.
A wing sweep of 10° was chosen based off of our sizing studies. This was done by performing a T/W ratio analysis through the use of our carpet plots on both 10° and 20° sweep angles. This analysis showed that on average, about 5000 lbs of structural weight was saved. This means that the structural weight decreased more than the fuel weight increased, and 10° was the preferable wing sweep between the two..
The high lift device used for the final design was upper surface blowing. This increased the lift during takeoff and landing, a requirement for Daedalus One’s ESTOL capabilities. This decision allowed Daedalus One to eliminate the need for circulation control on the wings, which would increase weight and decreases the power needs of the aircraft. Also, use of upper surface blown flaps reduces ground noise.
The previous design included a tri-tail comprised of a large vertical stabilizer, as well as two winglets with attached control surfaces. This was removed in favor of the current single tail configuration. Through analysis, it was determined that the tri-tail was unnecessary to maintain control of Daedalus One. Also, the removal of the unneeded tails resulted in a significant reduction in weight.
The forward wing extension allows the Daedalus One to carry more fuel on board, as well as gives it a location to mount the engines. This feature also helps move the Center of Gravity forward, which is essential for the aircraft’s stability.
Finally, an elliptical fuselage was favored over a cylindrical shape. The passenger cabin is wider than it is tall, which gives additional room to accommodate wider seats, and more aisle width. This shape allows for simpler fuselage construction and pressurization, while maintaining maximum passenger capacity and high comfort levels.
4. Advanced Technologies Integrated
The intent of Daedalus Aviation is to create an ESTOL aircraft at an affordable price. To help achieve this goal, advanced technologies were used in the aircraft design. The technologies applied will greatly help the Daedalus One accomplish its mission. Technologies included in the design of the aircraft are upper surface blowing, geared turbofans, and artificial intelligence (AI)/automated pilot.
4.1 Upper Surface Blowing
Daedalus Aviation chose to use upper surface blowing as the major high lift device used on the aircraft. Figure 10 depicts the concept of upper surface blowing. The engine is mounted at the leading edge of the wing and the exhaust is blow over the top of the wing. This method of blown flaps makes use of the Coanda effect, with the exhaust helping the flow stay attached and flow over the flaps at large deflection angles.
[pic]
Figure 10: Examples of Blown Flaps [5]
Figure 11 shows how the lift coefficient is affected by the different types of blowing. Internally blown flaps provide the highest increase in the lift coefficient; however, they do so at a cost. In order for internally blown flaps to operate, bleed air has to be taken from the engine which is then blown over the flaps. This effectively reduces the overall power created by the engines which was the main factor when deciding not to use internally blown flaps.
Externally blown flaps greatly increase the lift coefficient, also seen in Figure 11. They use the direct exhaust of the engines to help increase lift, much like upper surface blowing. The C-17 Globemaster utilizes externally blown flaps which allow the aircraft to take off on runways as short as 3,500 ft. However, Daedalus Aviation decided to use upper surface blowing because the efficiency is better than externally blown flaps. Upper surface blowing increases the lift coefficient 15% more when compared to externally blown flaps when the flaps are deflected at the same angle.
[pic]
Figure 11: Performance of Blown Flaps [5]
Figure 11 shows that upper surface blowing has the capability to increase the lift coefficient to approximately 7. The wing to be used on the Daedalus One was run through the computational fluid dynamics program, FLUENT. The results showed a clean Clmax of approximately 1.54. Using data obtained from FLUENT and data found in literature, it was concluded that with upper surface blowing the wing could achieve a CLmax of approximately 4 at small rotation angles. A higher CL is not necessary because 4 is sufficient to achieve the required takeoff distance, and increasing CL beyond this would greatly increase induced drag.
4.2 Composites
The Daedalus One will be a primary composite structure because having a light aircraft is crucial for short takeoffs and landings. The structure alone accounts for a great deal of the weight on today’s airplanes. By using all-composite construction, this weight can be reduced significantly. Current approximations of these weights savings range from 20% to 30% [4]. This is very beneficial in terms of fuel burn and takeoff distance. Because of this, many airplanes that are currently in their design phase have a significant portion of their construction made of composite materials. Most composite aircraft contain a variety of composite materials. The primary material used is typically a carbon fiber/epoxy composite. However, each composite type has different properties which are necessary for particular locations on the aircraft. An example is a location where carbon fiber meets aluminum, this connection typically causes corrosion in the aluminum, however another composite type, S-glass, may be used at the connection point to alleviate corrosion issues.
However, there are a few issues with composites. Building large composite structures can be difficult with today’s technology. Since molds of very large parts such as the fuselage or wings do not exist, they need to be created by gluing together smaller parts. This can cause a weakness in the structure at the point where they connect. Also, the repair of composites is not an easy or cheap process. In general, composites are more expensive than traditional materials. The technology is still fairly new, but very promising. Daedalus Aviation is confident that by 2058, these issues will have been resolved, and an all-composite construction of the aircraft will be possible.
4.3 Geared Turbofans
The engines Daedalus Aviation chose to use on the aircraft are geared turbofans. Geared turbofans offer many advantages over the turbofan engines currently in use. Geared Turbofans currently produce a 12% savings in fuel, 40% reduction in maintenance cost, and 70% lower emissions [4]. This is a huge improvement over current technology and provides much needed reductions in fuel and emissions to be competitive in 2058. By 2058, if these trends continue, there will be a 30% savings in fuel, 50% reduction in maintenance cost, and 75% lower emissions. The geared turbofan engines Daedalus Aviation is using for the Daedalus One each produce 25,000 lbs of thrust and have a specific fuel consumption (SFC) of 0.42/hr. Table 7 lists similar sized engines including their thrust and SFC. Figure 12 is the resulting graph of SFC versus service year. The trend line gives a SFC of approximately 0.6/hr. and by adding the 30% savings in fuel the SFC is brought down to 0.42/hr. These savings are made possible by having the high bypass fan geared to rotate at a slower speed than the core. This allows the blade size to increase therefore increasing the bypass ratio. Because of this, the number of blades inside the compressor and turbine can be reduced, lowering maintenance costs.
|Engine |Max Thrust |SFC (cruise) |Year in Service |
|RR Tay-651 |15400 |0.69 |1992 |
|IAE V2522-A5 |22000 |0.574 |1993 |
|CFMI CFM 56-3C1 |23500 |0.667 |1986 |
|JASC AVIA D-30KU-II |23850 |0.7 |1982 |
|GE CF34-10 |20000 |0.65 |2006 |
|GE CF34-8 |14510 |0.68 |2004 |
Table 7: Engine Thrust and SFC Over Time
[pic]
Figure 12: Decrease in SFC Over Time
4.4 Automated Pilot
Artificial Intelligence (AI) and Unmanned Aerial Vehicle (UAV) technology technologies are to be incorporated into the Daedalus One, making it safer and more efficient. In the aircraft, the pilot will be replaced by a computer. Instead of two skilled pilots, only one pilot would be needed to make sure the computer keeps operating and be able to take control in case of emergency. The reduction in flight crew will lead to lower operating costs. Eventually, even human air traffic controllers could be replaced by an AI-controlled system. The computer would be able to operate for long periods of time without the human errors that can come about through fatigue and stress. Also, they would not require the years of training humans need to perform their duties.
At first people may be afraid of surrendering control of an aircraft to a machine. However, there would still be a human in the cockpit that knows how to fly, so even if something happens to the computer, the airplane would not completely lose control. Over time, confidence in the system would likely increase as the technology becomes more commonplace.
4.5 Environmental Impact, Reliability, and Maintainability
The Daedalus One is an environmentally friendly, dependable, and easy to maintain aircraft. As mentioned above, by 2058 the geared turbofans will result in a 30% reduction in fuel emissions over today’s aircraft along with at least a reduction in noise levels about 20 dB below the current stage 4 noise regulations and a 50% reduction in maintenance costs. The major factor in reducing maintenance costs is the location of the engines. The two geared turbofans are mounted on the leading edge of the wing which makes them readily accessible for maintenance operations. Table 8 shows the current emissions maintenance cost and noise projections for geared turbofans.
[pic]
Table 8: Current Geared Turbofan Savings
5. Aircraft Sizing
5.1 Carpet Plot
The main tool used to determine the aircraft design point is the carpet plot. The original constraint analysis estimated that the Daedalus One should have a thrust-to-weight ratio (T/W) of approximately 0.23 and a wing loading (W/S) of approximately 84. Daedalus Aviation chose this as the design “center” point, and investigated wing loadings and thrust-to-weight twenty and forty percent high and low for both variables. In other words, wing loadings were varied between 50.4 and 117.6, and thrust-to-weight between 0.132 and 0.322.
Each combination of W/S and T/W was run through the sizing code (RDS, discussed below) to determine gross takeoff weight, fuel weight, and best range cruise speed. The fuel weight was not a constraint, but it is directly correlated to our constraint of fuel burned per seat mile. The conversion was made as follows:
[pic] (5.1.1)
The number of seats is a constant 108. The range of the aircraft was the target range of 1800 nmi in addition to the reserve of 200 nmi. RDS automatically determined if our cruise speed was below .75M (our threshold) and corrected the weights of the aircraft to match.
The first iteration of the carpet plot was done with the above ranges of wing loading and thrust-to-weight, an aspect ratio (AR) of 14, and a wing sweep of twenty degrees. After analysis, it was found that nearly all of the points that had a wing loading or thrust-to-weight below our center point did not meet any of the engineering requirements. The takeoff weights were too high, the fuel burn too high, the speed too low. The response to this was to make our initial “center” point instead a “corner” point. Thrust-to-weight was now varied in twenty, forty, sixty, and eighty percent increases, giving a total range of 0.23 to 0.414. Wing loading was varied twenty, forty, and sixty percent, and additionally investigated at 160 to have a more outside point for the analysis, giving a total range of 84 to 160.
[pic]
Figure 13: Carpet Plot
The constraints which had a direct impact in our aircraft sizing are shown on the above figure, and there are several interesting things to note in this carpet plot. Most surprising is the seemingly lack of correlation between fuel burn per seat mile and wing loading or thrust-to-weight. According to the generated values, FBPSM is directly related to the gross takeoff weight only. If there is any curvature at all to the constraint line, it is extremely small in our area of investigation. The fuel burn lines are shown as gold (threshold) and green (target). The second major constraint on the aircraft sizing was takeoff field length with one engine inoperative (OEI). The violet line represents the target field length with OEI, and the red line represents the threshold value.
From this analysis, the only acceptable design region for the aircraft is noted by the cyan cross-hatched region. In this region, the aircraft can achieve all threshold values, but unfortunately, achieving target values for fuel burn and field length simultaneously proved to be impossible. Daedalus Aviation chose the aircraft design point to achieve a balance between these two constraints, not favoring one over the other, but splitting the difference between them. Therefore, the design point was chosen as a wing loading of 120 lbs/ft2 and thrust to weight of 0.32.
5.2 Sizing
5.2.1 Sizing Software Summary
The sizing software selected by Daedalus Aviation is RDS. This selection was made due to a unique feature the software provides. RDS has a design module in which the user actually designs the aircraft. This module was found to be extremely helpful due to the unique design of Daedalus One. The other sizing codes available do not contain this feature, a lack of which could potentially cause inaccuracies in sizing due to the programs nature to assume a conventional design.
After completion of the aircraft model, the geometric data is then used for the aerodynamic, weights and propulsion analysis. Each analysis is run using the geometric data and uses it to create its respective data. After these analyses are run, the data is compiled into one master input file. In addition to the input file, a mission profile must also be created for sizing to the particular mission. The user must also input data for this master input file. The inputs from the user include preliminary values for the weight, wing loading and thrust to weight ratio. The program will perform iterations around the estimated weight to find a more accurate weight for the design. RDS will change some input values in order to allow the aircraft to perform the given mission profile.
5.2.2 Mission Profile
As required by the RDS software, a design mission profile is needed to properly size the aircraft. The mission profile selected by Daedalus Aviation was made for the mission most demanding given the aircraft’s size.
[pic]
Figure 14: Sizing Mission Profile
This mission can be considered a standard commercial mission. The missions cruise segment contains a 1,800 nmi range and a cruise speed of 0.75 Mach. In addition to this mission, a 200 nmi range was added for loiter and diversion time. This was done to account for the aircraft being forced to loiter over its destination airport or divert to a nearby airport due to weather or other factors.
5.2.3 Sizing Inputs and Results
The final sizing inputs for the Daedalus One are obtained from the design point generated by the carpet plots and can be seen in Table 9.
|Fuselage Length |97 ft |
|# Passengers |108 |
|# Crew |4 |
|Aspect Ratio |14 |
|Wing Sweep |10° |
|Wing Loading |120 lb/ft2 |
|Thrust to Weight Ratio |0.32 |
|Max Gross Takeoff Weight |100,000 lb |
|Estimate | |
|Empty Weight Estimate |80,000 lb |
|Max CL |4.0 |
|Max Cruise Speed |0.75 M |
|Max Cruise Altitude |42,000 ft |
Table 9: Sizing Inputs
Some of these inputs, such as the fuselage length and aspect ratio were used in the model creation; others such as the maximum gross takeoff weight estimate were used in the analysis data files. These values represent the final sizing results of Daedalus One. While these values could be refined to provide a more detailed sizing estimation, time restraints do not allow for further analysis. Technology savings was used for the crew number input data, artificial intelligence, composites structures and advanced engines.
Using these values the sizing analysis was run using RDS. The results from this analysis can be found in Table 10.
|Max Gross Takeoff Weight |87,100 lb |
|Empty Weight |34,700 lb |
|Payload Weight |27,800 lb |
|Fuel Weight |24,600 lb |
|Range |1,800 nmi |
|We/Wo |0.4 |
Table 10: Sizing Outputs
Like the inputs, these results are final. These results account for all technologies which may add or subtract weight, depending on the respective technology.
The results from this final sizing were checked against the historical database values as a “sanity” check to insure that the RDS software was providing reasonable values for the aircraft size. The following charts display the historical database and trend lines as well as where RDS currently places Daedalus One.
[pic]
Figure 15: Comparison to Historical Range and Takeoff Weight
[pic]
Figure 16: Comparison to Historical Takeoff Field Distances and Gross Takeoff Weight
[pic]
Figure 17: Comparison to Historical Gross Takeoff Weights and Passenger Capacity
As can be seen in Figures Figure 15, Figure 16, and Figure 17, the current sizing analysis places Daedalus One off the trend lines. This is expected due to the nature of the technological advancements used in the aircraft design.
6. Aerodynamic Analysis
6.1 Airfoils
The Daedalus One has a very difficult design stipulation. It requires a short takeoff distance which means high lift at low speeds. This usually leads to high cambered, thick airfoils. However, the goal was to also have the aircraft capable of cruising in the transonic region which requires exactly the opposite type of airfoil from takeoff; it needed a low camber thin airfoil to reduce drag. This is where the supercritical airfoils step in as a perfect blend of high speed cruising performance while still being able to maintain low speed performance.
Keeping these requirements in mind, a mid range thickness of about 10% to 15% was sought after with a slight camber and in the supercritical region. This requirement lead Daedalus Aviation’s selection of the NASA second generation SC 20712. Although this airfoil more than met the requirements for cruise, being designed to have a cruise Cl ≈ 0.7 as indicated by the name, it was chosen as a representative wing for the aircraft until further studies and modifications could be made. The supercritical has a unique design as can be seen in Figure 18.
[pic]
Figure 18: Main Airfoil NASA SC 20712
The basic design principal of the supercritical airfoil is to delay the onset of supersonic flow bubbles. These bubbles have normal shock waves associated with them which greatly increase drag and cause airflow separation. To avoid this phenomenon, supercritical airfoils typically have a flatter upper surface causing less flow acceleration and having a high cambered aft section. This causes the wing to have a high rear loading which moves the neutral point of the airfoil back. Since a supercritical airfoil was used the neutral point was assumed to be a mid chord rather than at the standard quarter chord during analysis.
Since there is very little data on supercritical airfoils, Daedalus Avaition performed its own analysis of the airfoil in Fluent using the two dimensional settings. By specifying a pressure far field as the boundary conditions to define the flow and setting up turbulent and laminar regions, the airfoil was analyzed at several angles assuming a takeoff speed of 115 kts. The laminar region was defined as the first half of the bottom side of the airfoil. The rest of the regions were modeled as turbulent. The residuals were monitored during the iterations to show the answer was well converged along with the coefficient of lift and drag. To show the solutions were well converged, an example of the convergence history for the force monitors is shown in Figure 34 and Figure 35 in the appendix.
The Fluent analysis yielded the following lift curve slope in Figure 19. From this graph, a Clα was obtained to use in the stability analysis, a max Cl of about 1.7 was assumed for takeoff lift calculations, and a stall angle of 18° was assumed for performance considerations. Due to the airfoil being cambered, there is lift at zero angle of attack, which gave a sanity check of the results from Fluent. A cruise case scenario was also run to give a cruise lift coefficient of Cl = 0.55 at zero angle of attack. This translates to a CL = 0.49 which meets the needs for the aircraft. This cruise CL was found using equation 12.15 from Raymer.
[pic] (6.1.1)
It is re-iterated here that this airfoil is only a representative airfoil for the Daedalus One and within the next 30 years, further studies and development of a super critical airfoil will endure.
[pic]
Figure 19: 2D Lift Curve Slope of SC 20712
[pic]
Figure 20: NASA SC 20012
The selection for the canard and vertical tail airfoil also followed along the lines of a supercritical airfoil. Since symmetric airfoils are commonplace on current aircraft, a NASA SC 20012 was chosen for the canard vertical tail. Upon running analysis, Figure 21 was obtained using Fluent with a similar set up conditions as with the main wing. The complete upper surface was modeled as turbulent and the lower surface to the trailing edge was modeled as laminar. The airfoil was also analyzed at several angles of attacks at a takeoff speed of 115 kts. From the analysis a Clmax approximately equal to 1.16 was used for takeoff rotation analysis as well as a Clα equal to 0.085. A “sanity” check of having zero lift at zero angle of attack helped in verifying the Fluent analysis. This airfoil selection was also chosen as a representative for what will go on the aircraft and further studies will provide and well developed supercritical airfoil for the aircraft.
[pic]
Figure 21: 2D Lift Curve Slope of SC 20012
6.2 High Lift
As discussed in section four, Daedalus One will employ upper surface blowing with a plain flap on the inboard and double slotted fowler flaps on the outboard to achieve the necessary lift for takeoff. During sizing a CL of 4 was assumed and the aircraft sized and tailored to this for takeoff. After research, it was shown that upper surface blowing is capable of achieving a CLmax of 7 [5] which far exceeds the needs of the aircraft. The Daedalus One will have a similar setup to those research aircraft used in the studies, having a forward mounted engine on the upper surface of the wing with plain and double slotted fowler flaps. Having a concern for one engine out on takeoff and the rolling moment associated with it, according to Cambell, this will at most induce a roll coefficient of 0.25 to -0.25 for a ΔCLmax of 2. Due to the high aspect ratio wings and having large moment arms, the ailerons will easily be able to compensate for the rolling moment and has been demonstrated of being feasible on the YC-14. These flaps were modeled as being one third the chord size of the wing which is typically standard for aircraft of this size. Further computational fluid dynamic and wind tunnel studies will need to be done to validate the design.
6.3 Drag Build Up
The drag estimation for the Daedalus One was broken down into three sections, parasite drag, induced drag, and wave drag. For parasite drag, a component build up method from Raymer’s text [6] was used and programmed into MATLAB. The basic equation used for CD0 was:
[pic] (6.3.1)
The friction coefficient was modeled for a flat plate in turbulent conditions via the equation:
[pic] (6.3.2)
R in the equation represents Reynolds number and was chosen as the minimum between:
[pic] (6.3.3)
[pic] (6.3.4)
When determining the cut off value for Reynolds number, the skin roughness value was chosen for smooth paint from table 12.4 in Raymer [6] with a 10% savings included for development new materials. For the form factors there were three equations used depending on the component being modeled. For the wing, canard, and vertical tail the form factor was:
[pic] (6.3.5)
[pic] is the chord wise location of the airfoil maximum thickness point. For the fuselage the form factor is:
[pic] (6.3.6)
f represents the fineness ratio which is equal to the length over diameter. The nacelles on the engines have a form factor of:
[pic] (6.3.7)
When determining the CD0 for the wing, a factor of one was chosen for Q since there is little interference drag from the wing to the fuselage due to advances in blending the two bodies. Other assumptions included in the drag build up were adding 5% to the values for the canard and tail due to gaps for control surfaces. 10% was also added for the interference of the nacelles with the wing. For takeoff conditions additional items added to the component build up were the flaps and landing gear. For flaps, the change in CD0 was modeled as:
[pic] (6.3.8)
The Fflap was chosen to be 0.0074 for slotted flaps from Raymer since the majority of the flap area will be double slotted flaps and Cf represents the chord length of the flap. For the landing gear, a frontal area method was used with values from table 12.5 in the Raymer textbook. Included were the frontal and tandem wheels and struts. An interference factor of 10% was added to the landing gear computation.
Induced drag as modeled via the classic equation:
[pic] (6.3.9)
AR represents the aspect ratio of the aircraft which is 14 and e is the Oswald Efficiency factor. Due to the high aspect ratio of the wing, an Oswald Efficiency factor of 0.83 was chosen since there are no accurate models to predict the efficiency factor of a high aspect ratio, slightly swept wing.
The final component of drag included in the calculations was wave drag. Due to the use of supercritical airfoils, drag divergence for the airfoil was increased by 16%. This is based of the study done on the F-111 in which they were able to increase the drag divergence from 0.76 to 0.88 by converting to supercritical airfoils [7]. This lead to a mach drag divergence number of 0.86 with a critical mach number of 0.78. Based upon the hybrid method proposed by Professor Crossley which included multiple equation fitting to existing data bases, equations 6.3.10 and 6.3.11 model the wave drag below drag divergence and above drag divergence.
[pic] (6.3.10)
[pic] (6.3.11)
A 10% reduction in wave drag was assumed due to advances and the use of supercritical airfoils.
6.4 Drag Polars
Various configurations were chosen when creating the drag polars for the Daedalus One. For analysis, a drag polar was created for cruise at various speeds, and for takeoff and landing configurations. The difference in takeoff and landing configurations is the deflection of flaps from 40° to 60°. As a sanity check the drag polars did vary with lift and there was a major increase in drag upon reaching the critical mach number. Figure 22 and Figure 23 show these drag polars. From the drag polar at cruise, a L/D for cruise was found to be around 21. [pic]
Figure 22: Cruise Configuration Drag Polar
[pic]
Figure 23: Takeoff and Landing Configuration Drag Polar
7. Performance
7.1 Flight Envelope
Using the RDS software, Daedalus Aviation generated a flight envelope diagram. The leftmost line on the flight envelope represents the stall limit, that is, that the aircraft will stall under any condition left of the line. The rightmost line represents the dynamic pressure condition, which indicates that due to drag the aircraft cannot fly under any condition to the right of that curve. The ceiling constraints are defined by the ability of the aircraft to climb. At the service ceiling, the aircraft must be capable of climbing at one hundred feet per minute, and the absolute ceiling is where the climb rate of the aircraft is zero; it cannot ascend any higher.
The flight envelope is shown in Figure 24.
[pic]
Figure 24: Flight Envelope
7.2 V-n Diagram
Daedalus Aviation also employed the RDS software to generate a V-n diagram, which shows the acceptable load limits of the aircraft. The system requirements for the Daedalus One mandated that the aircraft should be capable of a 2G maneuver at cruise altitude. From this, the design load factors were chosen as shown in Table 11
|Load Factor |Gs |
|Design Positive Load Factor |3 |
|Design Negative Load Factor |-1,5 |
|Ultimate Load Factor |4.5 |
Table 11: Load Factors
From these inputs, RDS generated the V-n diagram as shown in Figure 25.
[pic]
Figure 25: V-n Diagram
7.3 Best Range and Endurance Velocities
To find the velocities for best range and endurance, a graphical approach was used to obtain the values. From Brandt [8], the velocity for best endurance occurs at the minimum drag for the cruise configuration and the velocity for the best range occurs on the tangent on the curve from the origin. This method is illustrated in Figure 26. For the Daedalus One, the best endurance cruise speed is Mach = 0.55 and the best range speed is Mach = 0.75 although the Daedalus One is capable of cruising in the range of Mach = 0.7 to 0.8 efficiently due to little change in drag at these speeds.
[pic]
Figure 26: Demonstration of Best Range and Endurance Velocities
7.4 Takeoff and Landing Parameters
Due to the nature of the requirements, the Daedalus One is pushing the takeoff and landing parameters to the extreme for aircraft of this size. These takeoff and landing performance parameters are achievable due to the high aspect ratio wings and the CLmax from the upper surface blowing. To start, a takeoff and landing stall speed were defined for takeoff gross weight, landing weight after the mission, and max landing weight. Equation 7.4.1 describes how stall speed was found. In order to keep CLmax the same for both takeoff and landing due to the variation in thrust, it was assumed that the takeoff deflection angle for the flaps would be 40° and for landing it would be 60°.
[pic] (7.4.1)
The weights used were the max takeoff weight, max landing weight, and max takeoff weight minus fuel. Once stall speed was defined, the takeoff velocity was defined as 1.1 times the takeoff stall speed which was taken from Raymer[6]. The ground roll could then be found by using equations 17.102-17.104 from the Raymer textbook.
[pic] (7.4.2)
[pic] (7.4.3)
[pic] (7.4.4)
[pic] (7.4.5)
A value of 0.03 was chosen for the ground rolling resistance based on a dry concrete runway. For takeoff an initial velocity of zero was used for Vi and a final velocity of 103 kts for Vf.
To define the approach speed, 1.3 times the stall speed for landing configuration was used and for touch down speed, VTD is equal to 1.15 times the stall speed. Also used in the calculation was flare speed which was defined as 1.23 times the stall speed. To calculate the landing ground roll, equations 7.4.2-7.4.3 were used with an initial velocity set to VTD and a final velocity set to zero. Also taken into consideration were thrust reversers which were set to 40% of max thrust. To calculate the flare distance, a load factor of 1.2 was used with equations 10.107 and equations 17.110 and 17.111 from the Raymer textbook [6]. An angle of 3 degrees was used for the approach angle which is typical for most transport aircraft.
[pic] (7.4.6)
[pic] (7.4.7)
[pic] (7.4.8)
Since the flare is typically done over the runway, the flare distance was added to the landing ground roll distance to come up with the total landing distance which does not include landing over a barrier. Table 12 summarizes the findings of the takeoff and landing study.
|Takeoff Stall Speed |94 |kts |
|Takeoff Speed |104 |kts |
|Approach to Landing Stall Speed (no fuel) |82 |kts |
|Approach to Landing Speed (no fuel) |106 |kts |
|Approach to Landing Stall Speed (max landing weight) |90 |kts |
|Approach to Landing Speed (max landing weight) |118 |kts |
|Takeoff Ground Roll |1150 |ft |
|Landing Ground Roll (no fuel) |740 |ft |
|Landing Ground Roll (max landing weight) |810 |ft |
Table 12: Takeoff and Landing Parameters
8. Propulsion
8.1 Propulsion System Description
The propulsion system selected for the Daedalus One are geared turbofans. Geared turbofans use a jet core similar to a direct-drive turbofan. However in a geared turbofan, turbine power to the fan is transmitted through a transmission rather than being driven directly. This allows the fan size, and consequently the bypass ratio, to be increased. The Daedalus One is designed to use two engines with a maximum sea-level thrust of 25,000 lbs each. The engines are modeled with a bypass ratio of 8 and a specific fuel consumption of 0.42 per hour.
The jet engine core operates on the Brayton cycle. Air enters the engine through the inlet and is compressed by the fan and compressor. The compressed air enters the combustor, where fuel is mixed and burned, increasing the enthalpy of the flow. The flow then passes through a series of turbines which extract power to run the fan and compressor. The flow is exhausted through a nozzle. A large portion of the inlet air mass is bypassed around the engine after exiting the fan, and is exhausted though a nozzle and is mixed with the core exhaust to reduce noise. Thrust from this type of engine is generated by exhausting a mass of air at a higher velocity than free stream (called momentum thrust) and by any pressure differential that exists between the exhaust and ambient flow (called pressure thrust).
8.2 Thrust Available and Required
[pic]
Figure 27: Thrust Available and Required at Cruise at 35,000 ft
Figure 27 shows the thrust available and the thrust required as a function of Mach number for a cruise condition at 35,000 ft. The drag was found using a component build-up as previously discussed in the aerodynamics section. The thrust available was modeled by equation 8.2.1 from Brandt [8].
[pic]] (8.2.1)
Below M 0.3, the term 0.3/M(( is set to unity because air can be considered incompressible at low speeds. From Figure 27, it is found that the maximum cruise at 35,000 ft is M 0.85, which is also approximately the drag divergence Mach number.
Figure 28 shows the thrust available at takeoff conditions at sea level and high-hot (5,000 ft + 25°F) conditions. The drag at these conditions is for high-lift devices deployed and landing gear extended. The thrust was again modeled using Equation 8.2.1. From Figure 28 it is found that in the takeoff configuration the maximum speed at sea level is approximately M 0.29 and at high-hot conditions M 0.28.
[pic]
Figure 28: Thrust Available and Required at Takeoff
9. Structural Layout
[pic]
Figure 29: Top View of Load Paths
The layout of the internal structure of the Daedalus One was important to consider. Proper use of reinforcing structures allows the aircraft to retain structural integrity while maintaining a minimal weight. Stringers were used as the fuselage reinforcement. Since composite construction was utilized, these stringers are molded directly to the inside of the fuselage. They are mainly comprised of 0° laminate plies. The weight of these structures is reduced simply because they are made of composite material. Also, since they are part of the fuselage, there is no need for fasteners, further reducing the weight. The two main load-bearing structures are the wing and canard boxes. These give the canard and wing, respectively, an attach point to the fuselage. Since they are integral parts of the airframe, their placement was critical. In addition, spars were needed to reinforce the wing, since a large portion of the aircraft weight is affixed to it. The engine attachment point lies directly on top of the engine spar, and the kick spar allows the entire rear landing gear assembly to be placed under the wing.
[pic]
Figure 30: Side View of Load Paths
The above figure shows additional detail pertaining to the tail assembly. The canard and wing boxes go above and below the passenger cabin respectively, so there is no interference with the interior of the aircraft. This view shows the two rear bulkheads that are needed to attach the tail to the fuselage
[pic]
Figure 31: Wing Load Paths
This is an isolated view of the construction of the wing box, as well as more detail on the spars. It shows a clearer representation of how the engine is placed in relation to the engine spar, and the kick spar needed for the landing gear assembly. Since the landing gear folds up into the wing and fuselage, it is necessary for this spar to carry all of the weight from the machinery needed to operate the landing gear bay, as well as raise and lower the gear.
10. Weights, Balance and Stability
10.1 Weight Group Breakdown
During the aircraft sizing the weights of the respective components was calculated by RDS. These weights can be divided into three different groups: structure, propulsion, and equipment.
The primary portion of the aircraft’s empty weight is that of the structures group. This group contains the wing, fuselage, tail and other structural members. The weight breakdown of this group is contained within Table 13.
|Component |Weight |
|Fuselage |7,200 lb |
|Wing |8,300 lb |
|Canard |600 lb |
|Vertical Tail |600 lb |
|Landing Gear |3,300 lb |
Table 13: Structural Weight Breakdown
The second largest weight group is the propulsion group. This group contains the engines, fuel tank and support systems. The weight breakdown of this group is contained within Table 14.
|Component |Weight |
|Engines |7,000 lb |
|Fuel System |900 lb |
|Support Systems |200 lb |
Table 14: Propulsion Weight Breakdown
The smallest weight group is the equipment group. This group contains the controls, avionics and other aircraft systems. The weight breakdown of this group is contained within Table 15.
|Component |Weight |
|Controls |2,800 lb |
|Avionics |2,100 lb |
|Instruments |300 lb |
|Electrical |900 lb |
|Furnishings |800 lb |
|Air Conditioning |600 lb |
|Anti Ice |200 lb |
Table 15: Equipment Weight Breakdown
10.2 CG Position
During different stages of the aircrafts mission, the center of gravity will drift between several positions along the aircraft’s length.
[pic]
Figure 32: CG Diagram of Daedalus One
As can be seen from Figure 32, the center of gravity will range from 49 to 58 ft aft of the nose. While there are a few locations where the center of gravity is aft of the static margin, however these conditions are for ground configurations and will not result in a statically unstable aircraft during flight.
10.3 Neutral Point and Static Margin
A critical part of finding the longitudinal static stability of the Daedalus One is to locate the neutral point. The neutral point can be found by
[pic] (10.3.1)
where xn is the neutral point location, xac is the aerodynamic center location, ccan is the canard volume coefficient, and acan and a are the 3D lift curve slopes of the canard and wing, respectively. The aerodynamic center is found by
[pic] (10.3.2)
where xc/4can and xc/4 are the distances from the nose to the quarter mean chord of the canard and wing, respectively, and Scan and S are the planform areas. The canard volume coefficient is found by
[pic] (10.3.3)
where lcan is the distance between the mean quarter chords of the wing and canard (and is negative because the canard is in front of the wing) and [pic]is the mean chord of the wing. It is important to note that the volume coefficient is calculated solely for the purpose of finding the neutral point and is found independently of historical guidance provided by Raymer.
The 3D subsonic lift curve slope was approximated by Raymer [6]
[pic] (10.3.4)
[pic] (10.3.5)
[pic]. (10.3.6)
Under guidance from Raymer, the quantity
[pic]. (10.3.7)
By this method, the neutral point is found to be at 56.7 ft aft of the nose. At gross takeoff weight, the center of gravity (cg) is estimated to be at 55.8 ft aft of the nose, yielding a reasonable static margin of 11.3%. If the aircraft is fully loaded and burns all fuel except reserves, the cg travels to approximately 58.6%. If the aircraft is fully loaded and burns all fuel including reserves, the cg moves to approximately 49.0 ft from the nose, and the static margin becomes 100%. With the static margin growing so large during flight, the Daedalus One could have agility challenges in low-fuel situations. This stability increase could be delayed by having a controlled fuel burn in which the fuel in the forward tanks if burned first, while the remainder of the fuel could be pumped into aft tanks in the tail cone to shift the cg aft. If the Daedalus One is flying at less than maximum passenger capacity, the cg could also be shifted aft by placing passengers in the rear of the cabin.
10.4 Canard and Elevator Sizing
The canard sizing was dependent on providing enough lift in the cruise configuration to keep the nose aloft and to be able to provide a large enough moment to rotate the aircraft on takeoff. From the static margin calculations in 10.3, a canard area of 300 square feet was used for the analysis. To obtain the static margins varying from 11% to 100% of the mean aerodynamic chord, this placed a CLα constraint of 0.078 on the canard. From the Fluent analysis in section 6.1 and converting Clαcanard to CLαcanard, it was found that the airfoil selection and size met the requirements for cruise. For takeoff, a moment balance was used with the static margin for max gross takeoff of 11.3%. This places a nose down moment of 67,000 lbs/ft or only an extra load of 2000 lbs to be lifted. This can be easily compensated for with elevators on 1/3 the chord of the canard.
10.5 Vertical Tail Sizing
To calculate the vertical tail size, a one engine out condition during takeoff is assumed, because the one engine out condition requires more force than a cross wind condition. The key parameter for calculating the vertical tail size is the yawing moment coefficient. The yawing moment coefficient required to maintain steady flight with a one engine out condition is given by:
[pic] (10.5.1)
Where T is the maximum available thrust at the given Mach number and altitude, le is the length of engine arm, lt is the length of tail arm, and Dewm is the drag due to the windmilling of the failed engine.
The drag due to the windmilling of the failed engine is calculated by:
[pic] (10.5.2)
[pic] (10.5.3)
Where :
di is the engine inlet diameter
M is the Mach number
Vn is the nozzle exit velocity
Vn/V= 0.92 for high bypass ratio engines
Sref is the wing reference area
The free body diagram of a twin-engine aircraft is shown below
[pic]
Figure 33: Aircraft Reference Free Body Diagram
[9]
From this figure it can be found that
[pic] (10.5.5)
Then
[pic] (10.5.6)
and
[pic] (10.5.7)
Finally
[pic] (10.5.8)
Where Clvtial is determined by the the method given by Raymer book, which is 1.5751. So the total size of vertical tail is 310 ft2.
11. Cost Analysis
The estimated costs of the Daedalus One were determined by first estimating a total cost per aircraft and a desired profit from each aircraft. After the total cost of the aircraft was found, the break-even number of aircraft and sale price were estimated.
An acquisition cost model was developed from the RAND DAPCA IV model. Once the equations of the model were known, it could be applied to the new aircraft to obtain an appropriate acquisition cost given the gross takeoff weight and cruise Mach number.
The acquisition cost for the Daedalus One is $24.4 Billion, as determined by the cost model. After 5 years of production, Daedalus One estimates that 500 aircraft will have been sold. By a pre-determined 10% profit that Daedalus Aviation will make on the aircraft, the break-even number of aircraft is 455. The sale price per aircraft is $54 Million.
The development cost includes engineering, tooling, development support, flight testing and certification. From the DAPCA IV model, cost of each development categories can be estimated. The flyway cost includes the engine, avionics, seats, ceiling and floor fabrication as well as labor, tools, manufacturing and materials. The estimated engine cost, $6.3 Million each, was determined by the equation given by DAPCA IV model. Because Daedalus One incorporates the use of AI avionics, the cost of avionics is $3.85 Million/aircraft. The cost of the seats, ceiling, floors etc was estimated at $0.19Million/aircraft based on the Raymer book. A breakdown of the flyaway cost, development cost and a summary of the total cost are shown in tables below.
|Total RDT&E + Fly away |$24.4 Billion (2008 USD) |
|Quantity of aircraft |500 |
|Acquisition Cost per Aircraft |$48.8 Million (2008 USD) |
|Profit Percentage |10% |
|Break-Even Number |455 |
|Sale Price per Aircraft |$54 Million (2008 USD) |
Table 16: Summary of Cost Analysis
|Research and Development Costs |Engineering |$2.4 Billion (2008 USD) |
| |Development |$225 Million (2008 USD) |
| |Tooling Support |$1.32 Billion (2008 USD) |
| |Flight Testing and certification |$49 Million (2008 USD) |
| |Total RDT&E |$4 Billion (2008 USD) |
|Flyaway Costs |Engine |$9.45 Billion (2008 USD) |
| |Avionics |$2.9 Billion (2008 USD) |
| |Seats, Ceiling, Floors etc |$141.7 Million (2008 USD) |
| |Labor, tools, manufacture, materials |$7.9 Billion (2008 USD) |
| |Total flyaway cost |$20.4 Billion (2008 USD) |
Table 17: Breakdown of Project Costs
The annual operation cost of the Daedalus One was also determined. The operating cost includes two parts. One is variable costs such as fuel cost, maintenance costs, and salary of the flying crew. The other one is fixed costs which includes annual insurance. The annual flying time was estimated to be 3000 hours. Both variable and fixed costs can be estimated by the equations given by Raymer. In 2008, the fuel price was assumed to be $2.50 per gallon. Then the estimated operating cost is approximately $11.8 Million per aircraft per year. A summary of the variable and fixed cost is shown below.
|Operating Cost | | |
| | | |
|Variable Costs: | | |
| |Total Hours/year |3000 |
| |Fuel price per gallon |$2.50 (2008 USD) |
| |Fuel burn per hour |12.31 |
| |Maintenance cost/hour |$782 (2008 USD) |
| |Crew cost/hour |$589 (2008 USD) |
| |Total variable cost per year |$11.7 Million (2008 USD) |
| | | |
|Fixed Costs: | | |
| |Annual Insurance |$0.12 Million (2008 USD) |
| | | |
| |Total Operating Cost per year |$11.8 Million (2008 USD) |
Table 18: Summary of Operating Costs
|Variables |Description |
|N |number of Passenger |
|We |empty weight |
|W0 |Takeoff Weight |
|V |Max Velocity |
|Vc |Cruise Speed |
|Q |Quantity |
|FTA |Number of Test Aircraft |
|Tmax |Max Thrust of Engine |
|Mmax |Max Mach Number of Engine |
|Tti |Engine Turbine Inlet Temperature |
|Waw |Weight of Avionics |
|Re |Cost of Engineering per Hour |
|Rt |Cost of tooling per hour |
|Rm |Cost of manufacturing per hour |
|Rq |Cost of quality control per hour |
|Neng |Number of Engines |
|He |Engineering Hours |
|Ht |Tooling Hours |
|Hm |Manufacturing Hours |
|Hq |Quality control Hours |
|Cd |Development Support Cost |
|Cf |Flight Test Cost |
|Cm |Materials Cost |
|Ceng |Engine Production Cost |
|Cinterior |Interior Cost |
|CostDaedalus |Cost of RDTE+Flyaway |
Table 19: Description of Cost Variables
[pic] (11.1.1)
[pic] (11.1.2)
[pic] (11.1.3)
[pic] (11.1.4)
[pic] (11.1.5)
[pic] (11.1.6)
[pic] (11.1.7)
[pic] (11.1.8)
[pic] (11.1.9)
[pic] (11.1.10)
[pic] (11.1.11)
12. Future Steps
Several more steps need to be taken in order to more completely conceptualize the design of the Daedalus One. The first of these steps would include more detailed analysis into the aerodynamic performance of the aircraft. This includes development and tailoring of supercritical airfoils, CFD, more detailed drag analysis, and control surface sizing for the rudders and ailerons. Further structural analysis would also be required to fully understand the effects of equipment placement within the aircraft. Upon completion of these analyses, sizing would once again be run to obtain a more accurate aircraft size. This would then be correlated into an updated version of the Daedalus One CAD model. However due to time constraints these tasks can not be completed.
References
1. Bureau of Transportation Statistics “RITA | BTS | Transtats” [Online] Available (Jan. 24, 2008)
2. NFDC Runway Database. . (Jan. 24, 2008)
3. Embraer. “Embraer Commercial Jets” [Online] Available (Jan. 22, 2008)
4. Sun, C.T. Personal Interview. 13 Jan. 2008.
5. Cambell, John P. “Overview of Powered-Lift Technology” The George Washington University, Joint Institute for Acoustics and Flight Sciences. 1976
6. Raymer, Daniel P. Aircraft Design: A Conceptual Approach. 4ed. Reston, Virginia: American Institute of Aeronautics and Astronautics, Inc. 2006
7. Scott, Jeff. “Supercritical Airfoils” 2000
8. Brandt, Steven A. Introduction to Aeronautics: A Design Perspective. 2nd Edition. Reston, VA. American Institute of Aeronautics and Astronautics, Inc. 2004
9. Grasmeyer, Joel. “Stability and Control Derivative Estimation and Engine-Out Analysis”. (Jan,1998)
10. Pratt-Whitney. “Pratt & Whitney’s Geared Turbofan Demonstrator Engine Completes Phase I Ground Tests Ahead of Schedule” [Online] Available vgn-ext-templating/v/index.jsp?vgnextoid=2e35288d1c83c010VgnVCM1000000881000 aRCRD&prid=37df431e0b418110VgnVCM100000c45a529f____ (February 14, 2008)
11. W. H. Mason “Some High Lift Aerodynamics Part 2 Powered Lift Systems” Virginia Tech University (1998)
Aircraft Order Form
Section 1: Identification
Name: _________________________________________________________________
Address: _______________________________________________________________
_______________________________________________________________
Phone: ( ____)_______-____________
SSN: ______-_____-_________
Mother’s Maiden Name: ________________________
Section 2: Airframe
Number of Aircraft: _______ (Base price $38,000,000)
Options Desired (check all that apply)
______: First Class Option ($85,000)
______: Main Gear Spinners ($500)
______: Nose Gear Spinners ($300)
______: Custom Paint Job ($2,450)
______: Neon “Mile-High Club” Sign ($600)
Select Color
□ “Slick” Blue □ “Cherry” Red □ “Emergency” Orange □ Green
______: Afterburners ($10,000… warning do not exceed Mach 1.2)
______: Acoustic Entertainment System (aka, the “pimpin’” stereo… $200 per seat)
______: With 85 Disk CD-Changer (add $20 per seat)
______: With Personal Video Screen (add $120 per seat)
______: With TiVo™ (add $5 per seat per month)
______: Fluffy ($485, feed not included)
Section 3: Financial
Subtotal (do not zero fill): $__ __ __ , __ __ __, __ __ __ , __ __ __ . __ __
Warranty Options (check one)
_____: “Icarus” 3-month Airframe Warranty (void if airplane cruises above 5,000 feet)
(Add $1,000,000)
_____: “Minotaur” 6-year Airframe and Power Plant Warranty (not available in Crete)
(Add $8,000,000)
_____: “Epic” Warranty (Lifetime)
(Add Homer)
Please direct any questions regarding warranties to Todd Bojjangles in ARMS 2102 2106 during the hours of 10 PM – 4 AM
Total Price (do not zero fill): $__ __ __ , __ __ __, __ __ __ , __ __ __ . __ __
Credit Card Number: ___________________________________________
CVC: _______________
Bank Account Number: _________________________________________
PIN Number:______________________
Oh look, we added fine print. Because fine print makes everything look much more official, don’t you agree? I mean, you are already giving us an inordinate amount of money, and we haven’t even discussed payment options, which ostensibly implies that you have to pay us cash. Lots of lots of cash. We do, however, accept grades valued at ‘A’ or higher, at an exchange rate of one ‘A’=$500. Higher, you ask? Yes, yes you can. You are really smart people, I have faith you can figure it out. It really won’t help you. The base price of the aircraft is thirty-eight million dollars (give or take) (38.000,000). I mean seriously… those ‘A’s can’t help you out that much. That’s because they can’t help us out that much. I’d really rather have seven million (7,000,000) dollars than straight ‘A’s in college. But y’know, I REALLY REALLY rather have BOTH. And if you can do that, we give you a really paltry discount. Don’t you feel special?
By signing this contract, you, by your own free will, do bequeath to Daedalus Aviation your soul, your money, your livelihood, and at least one (1) child, firstborn preferred. You also agree to give us one (1) arm, one (1) leg, and four (4) teeth. Yeah, we’re sick people.
All negotiations are final. By signing below you absolve Daedalus Aviation of anything you (and we) can possibly imagine. You can’t sue us, even if we suddenly are no longer in business by May 9th. ESPECIALLY if we aren’t in business by May 9th. In fact, let’s just be honest. You actually aren’t going to get an airplane at all. And we aren’t going to be in business after May 9th. So there. You are going to fork over MILLIONS of US dollars (we do accept Euros as well, but the numbers are all still the same) and/or (preferably and) good grades, and we will then run screaming into the night, having cheated you out of said hard earned cash. Following this, we will be drinking heavily in Rio. Rio is a nice place, I’m told. You should go there sometime. Actually you shouldn’t, because we will be there, laughing at you because you were actually stupid enough to give us your social security number. Do you know where your credit score is? It is nonexistent. Er…. It will be, once you fill out the form and sign below. Seriously, just sign it now.
Daedalus Aviation is not responsible if our AI system is a cardboard box with a Steven Spielberg movie in it, “ET fly home…”.
We are also not responsible if the plane crashes because of said cardboard box. Seriously, if you are still reading this, you should be dumping this in the fire by now.
This paper is for entertainment purposes only. If you pay us, we’re keeping it. Reading this fine print may cause dizziness, vomiting, fever, high cholesterol, spontaneous obnoxious laughter and an intense desire to give us all ‘A’s. Seriously, give us an ‘A’. Please consult your doctor if this is the first time you are reading this fine print. Also, consult your doctor if you feel the urge to give us something other than an ‘A’.
I hearby agree to all the terms and conditions laid out in this contract and agree to pay Daedalus Aviation the amount listed under the “Total Price” in Section 3. Or… give them all ‘A’s.
______________________________________ ________________
Date
______________________________________ ________________
Date
Appendix
[pic]
Figure 34: Convergence History of Cd
[pic]
Figure 35: Convergence History of Cl\
-----------------------
Lav
Electric
Electric
Galley
Baggage
Water
Fuel
Best Range
Minimum Drag
Taxi
Takeoff &
Climb
Step Cruise
For Best Range
Descend & Hold
Land & Taxi
Climb- Miss
Approach
Cruise
Descend & Hold
Land & Taxi
Taxi
TO &
Climb
Step Cruise
For Best Range
Descend & Hold
Land & Taxi
Climb- Miss
Approach
Cruise
Descend & Hold
Land & Taxi
Cruise
TO &
Climb
Descend
Land & Taxi
Taxi
Takeoff &
Climb
Step Cruise
For Best Range
Land & Taxi
Climb- Miss
Approach
Cruise
Descend & Hold
Land & Taxi
Spiral Descent
Daedalus One
Daedalus One
Daedalus One
GTOW
W0f + reserves
OWE + payload
OWE
We
We + trapped fuel
Baggage
Tow
Jetway
................
................
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