The Aerus DecaJet AA241B: Final Report Due on March 20, 2013 Christopher Pepper 1 Christopher Pepper The Aerus DecaJet AA241B: Final Report Contents 1 Introduction 4 1.1 Very Light Jets . .4 1.2 Project Motivation . .4 2 Fuselage Design 5 2.1 Diameter Choice and Cross Sectional Layout . .5 2.2 Layout . .5 3 Wing Design 7 3.1 Airfoil . .7 3.2 Planform . .9 3.2.1 Thickness to Chord Ratio and Sweep . .9 3.2.2 Wing Lift Distribution . .9 3.3 Wing Placement . 10 4 High-Lift Systems 12 4.1 Determining cl;max for Cruise, Take-off, and Landing . 12 4.2 Adjusting cl;max to CL;max ..................................... 12 5 Empennage Design 13 5.1 Vertical Tail Sizing and Location . 13 5.2 Horizontal Tail Sizing and Location . 13 5.3 Static Margin Calculation . 14 6 Propulsion 15 6.1 Engine Selection . 15 6.2 Nacelle and Engine Placement . 16 7 Drag Polar and 3-View Drawing 17 8 Structure 19 8.1 Loads Estimation . 19 8.2 Component Weight Estimation . 20 8.2.1 Wing Weight . 20 8.2.2 Horizontal Tail Weight . 20 8.2.3 Vertical Tail Weight . 21 8.2.4 Propulsion System Weight . 21 8.2.5 Fuselage Weight . 21 8.2.6 Landing Gear Weight . 22 8.2.7 Surface Controls Weight . 22 8.2.8 Auxiliary Power Unity Weight . 22 8.2.9 Computer Systems Weight . 22 8.2.10 Hydraulics Weight . 22 8.2.11 Electrical Weight . 22 8.2.12 Electronics Weight . 22 8.2.13 Furnishings Weight . 22 8.2.14 Air Conditioning Weight . 23 8.2.15 Operating Items Weight . 23 8.2.16 Flight Crew Weight . 23 Page 2 of 33 Christopher Pepper The Aerus DecaJet AA241B: Final Report 8.2.17 Flight Attendant Weight . 23 8.2.18 Payload Weight . 23 8.3 Total Weights . 23 9 Baseline Performance Estimation 24 9.1 Take-off Performance . 24 9.2 Landing Performance . 24 9.3 Second Segment Climb Performance . 25 9.4 Cruise Performance . 25 9.5 Baseline Summary Sizing Plot . 26 10 Optimizing the Design 28 11 Environmental Characteristics 31 11.1 Noise . 31 11.2 Emissions . 31 12 Future Work 33 12.1 Engine . 33 12.2 Materials . 33 12.3 Cabin Design . 33 12.4 Airfoil . 33 12.5 The Business End . 33 Page 3 of 33 Christopher Pepper The Aerus DecaJet AA241B: Final Report 1 Introduction The aircraft we selected to develop is the very light jet, or Air Taxi. We selected this mission to explore an aircraft design that may help make air travel a more personal experience. Current business jets are not well suited for the mission of an air taxi because they may be over designed for this role, having expensive capabilities that would be unused on this type of service. An air taxi would likely serve some of the more popular routes in the United States such as JFK to MIA. We should then design the vehicle to be capable of a range near 1000nm, to carry about four passengers, to need less than 3000ft runway, and to cruise in the range of Mach 0.6 to 0.8. Our goal therefore is to meet and not greatly exceed all of these requirements so to hopefully find a competitive niche in the market. 1.1 Very Light Jets The highest selling personal jet at this point is the Cessna Citation Mustang, which has delivered over 300 units. This is an important aircraft to consider due to its popularity and strong brand recognition. A new air taxi company would certainly consider this aircraft when in the acquisition phase. Another important aircraft is the newly developed and about to be released is the Honda Jet. This aircraft is currently undergoing certification and is expected to be delivered to customers within a couple years. This aircraft is an important analog to the DecaJet because it is Hondas first aircraft, and it is almost 10 years newer than the Cessna. The new technology used in the Honda Jet will make it a competitor in terms of operational cost. The Cirrus Vision SF50 is another good airplane, but this aircraft is not specifically intended to compete for commercial use. This airplane, and the Diamond D-Jet, is intended for the personal use market and as such is not specifically considered in this project. 1.2 Project Motivation The Aerus DecaJet is particularly well suited for a few commercial roles, which includes air taxi and rental. Currently, many companies offer the ability to charter an aircraft, and clients chose it for its convenience. Chartering an aircraft allows clients to fly into one of the thousands of smaller regional airports which are often nearer to their destinations. Trips are shorter, there is much less lead time in embarking on the journey, and the chosen aircraft are often more comfortable. A smaller aircraft reduces weight and operating cost, and the very light jet is more suited for small group travel. Because the aircraft has a range over 1000nm and can cruse at higher speeds, its unlikely to be the favored aircraft for short trips, such as perhaps from a business meeting in San Jose from San Francisco (less than 30nm) or even Philadelphia to NYC (85nm). Air travel over shorter distance like this is would probably be done with a helicopter since our aircraft would hardly get to cruise altitude at such a short distance. Some of the most popular routes in the US include San Francisco to Las Angeles (300nm) and New York to Miami (950nm). These are the likely routes best handled by an air taxi, which can provide comparable times with added convenience. An airplane designed to service routes will need an onboard bathroom. Page 4 of 33 Christopher Pepper The Aerus DecaJet AA241B: Final Report 2 Fuselage Design 2.1 Diameter Choice and Cross Sectional Layout Given that the average American male is 5'10" (70") tall, a good inner diameter for the aircraft fuselage will be 72". A larger fuselage would be more luxurious and allow for easier movement about the cabin, but this would come at the cost of additional weight and performance. We use the estimated 8% thickness to predict an outer diameter of 78". This gives a structural thickness of 3". Figure 1: Fuselage Cross Section The fuselage diameter allows for comfortable seat width of 20" and a reasonable aisle width of 15". All together, the majority of customers will be able to move about the cabin in full comfort. 2.2 Layout Lower Mach numbers constrain typical transport aircrafts to have a nose fineness ratio of 1.5 as a result of fuselage pressure gradients. Similarly, the tail cone is generally within the range of 1.8 to 2.0, and we choose 1.8 for our conceptual design. The nosecone is therefore 117" and the tail cone is 140". The aircraft will be furnished by the purchasing airlines, but a sample layout is included below. Among very light jet manufacturers, there are various opinions as to the necessity of an onboard lavatory. As this aircraft is intended for medium length flights, it is clear that installing one is a necessity. We however chose not to include a full galley or space for a flight attendant. A small refrigerator and some cabinet space should be more than sufficient for our chosen mission. To fit a lavatory, emergency exits, and seating for four, the cabin length will be 100". Page 5 of 33 Christopher Pepper The Aerus DecaJet AA241B: Final Report Figure 2: Fuselage Layout Two exits, one emergency and one standard, meet the FAA safety regulations. The layout will accom- modate five passengers, with two on the sofa-like seat in the rear of the aircraft. We have chosen to make the aircraft single-pilot certified. Page 6 of 33 Christopher Pepper The Aerus DecaJet AA241B: Final Report 3 Wing Design Since the configuration of our aircraft is similar enough to the Cessna Citation Mustang and the Honda Jet, we can look to these aircraft to choose reasonable preliminary values for various wing parameters. The first parameter to consider is wing area. The Cessna has a wing area of 210ft2. Using this as a benchmark, the wing area is chosen to be 150 ft2 or 13.9 m2. We next consider wing span, which we choose to be 37' where the Cessna uses a 43' span and the Honda Jet uses a 40' span. These two choices give an aspect ratio of 9.1. Knowing that the lift in cruise is equal to the weight of the aircraft, we can approximate this as 97% of the maximum take off weight for the start of cruise. The maximum take off weight we are designing for is 8600lbs or 3900kg. The equation for CL is L :97 · mg :97 · 3900kg · 9:81m=s2 C = = = = :33 (1) L 1 2 1 −4 3 2 2 q1Sref 2 ρv · Sref 2 · 3804 × 10 kg=m · (205m=s) · 13:9m 3.1 Airfoil The design altitude of the aircraft is FL350, where the atmospheric density is taken to be 3804×10−4kg/m3, and the dynamic viscosity is 142:2 × 10−7N · s=m2. The airspeed will be 400 knots or 205 m/s. For a wing area of 150 ft2 and a wing span of 37 ft, the average chord length will be approximately 4 feet or 1.25m. The Reynolds number at the cruise condition is therefore given by the following calculation. ρ · v · l 3804 × 10−4kg=m3 · 205m=s · 1:25m R = = = 6:85 × 106 (2) e µ 142:2 × 10−7N · s=m2 In anticipation of three-dimensional air flow effects, we choose a Cl that is about 20% higher than the expected need.