A201_PM8.docx

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Team Name Team Number RAAAW A201 AAE 251: Introduction to Aerospace Design Project Milestone 8 Due Thursday November 9 th , 11:59 PM ET on Brightspace Instructions Answer each question in this Project Milestone assignment as a team and record your team’s response in the “Team Response” box under each question. Complete each question in full sentences. Leave the “Peer Review Comments” box empty when your team submits your Project Milestone assignment. You will use these boxes for the three Peer Reviews in the semester. Update your google doc link on Brightspace by the due date specified in this assignment. Only one team member needs to submit on behalf of the entire team. 1

Drag Polar From the previous milestones, you should have estimates of and the aspect ratio. Use these estimates to sketch the drag ? ?,0 polar for your aircraft. Team Response Peer Review Comments 2

C L-max = 1.25 (from airfoil in previous PM) C D = C D0 + C L-max 2 / πA r e 0.10 = C D0 + (1.25) 2 / π * 7 * 1 Note: A r and e values based off assumptions in previous PMs C D0 = 0.0289 Plotted Function: C D = C D0 + C L-max 2 / πA r e 3

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Type of Engine What type of engine will your aircraft use? Justify your decisions. Team Response Peer Review Comments The aircraft will use a Wankel UAV Engine 741. This is an internal combustion engine that uses an eccentric rotary design to convert pressure into rotating motion. This engine was chosen because it is used in military surveillance drones including the AAI RQ-7 Shadow. This engine is advantageous for use in aircraft due to its compactness, light weight, and mechanical simplicity. AAI RQ-7 Shadow - Wikipedia Wankel engine - Wikipedia 5

Concept Generation Based on your calculated major design parameters and reference aircraft, generate at least three concepts for both your aircraft’s plant (reminder this will be the same for both refueling and scanning aircraft). Some prompts to get you started: What type of wings will the aircraft have and how will they be placed (e.g., overwing or underwing)? How many engines and where will they be placed? What type of landing gear will the aircraft have? Team Response Peer Review Comments 6

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Concept 1 ● High wing configuration, tapered wing planform with straight trailing edge, swept back leading edge, no twist, same airfoil section throughout ● T-tail ● Tricycle landing gear, retractable, mounted in fuselage, no doors ● Supply compartment, no door, suppsimple attachment to top of fuselage interior ● Nose mounted single engine Concept 2 ● Low wing configuration, rectangular planform wing ● Conventional tail ● Single engine ● Wing-box tricycle landing gear Concept 3 ● High wing configuration, tapered and twisted wing planform ● T-tail ● Twin engine, mounted under each wing ● Tricycle landing gear, fuselage mounted, with doors ● Concept Selection Based on the requirements you generated earlier this semester, create a set of concept evaluation criteria. Use these criteria to evaluate the concepts you generated and select the one most suited for your requirements. Justify your final decision. Team Response Peer Review Comments 7

Evaluation criteria: ● Stability (roll, pitch, yaw). Ours is not an aerobatic aircraft, we need it to safely cruise along its path and keep the camera steady. High wing configurations naturally have better roll stability due to having the center of gravity below the center of lift. Low wing aircraft would need dihedral to produce comparable roll stability, but dihedral adds structural complexity. So a high wing is ideal for roll stability. Also, yaw stability is enhanced by wing sweep (say the plane yaws to right, so the left wing will face the free stream more directly, resulting in more lift, more induced drag, and so it pulls the plane back to left). As to pitch stability, we will have to play around with the distance of the horizontal stabilizer from the center of lift and center of gravity as well as the positioning of the fuel and payload, but these details are left for next time. We give this category a weight of 5 in the decision matrix. ● Camera field of view. We must make sure the landing gear is not in the way of the camera, so retractable gear is ideal. Non-retractable gear is fine if it doesn’t protrude much from under the fuselage or the camera can be lowered out of the fuselage during flight. This criterion is very important, but since the aircraft is moving, a blind spot can be captured a few seconds later once the wheel moved off it, so we give this a weight of 4 . ● Takeoff from a no prep runway. The landing gear must withstand bumps etc. Also, low wings reduce takeoff distance, with the disadvantage of increasing landing distance (due to ground effect). Sufficient ground clearance must be ensured for propeller blades, fuselage, instrumentation and camera. ● Ease of supply drop. The dropping operation should not take long so superfluous hatch openings and load projections should be avoided. A simple release is best. Meaning there should not be anything behind the supply compartment that the supplies could impact (since drag will tend to hold the supplies back while the aircraft continues forward). So a rear mounted engine is not a good idea. Weight 5 because supply drop is the whole point of the mission. ● Structural simplicity. T-tails for example are heavier than conventional tails, retractable gear adds weight as well, low wing allows for simpler main gear integration and handling of landing loads. Now, the point of the mission is to be safe and reliable, so if tradeoffs have to be made in favor of other criteria, it’s OK to make the aircraft a bit heavier, so we give this a weight of 3 . 8

Criteria Weights Concept 1 Concept 2 Concept 3 Stability 5 5 3 5 Camera FOV 4 4 Ease of Takeoff 5 3 Easy of Supply Drop 5 4 Structural Simplicity 3 5 Totals 100 9

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3D Model of your aircraft Start working on the 3D model of your aircraft(s). Include a draft of the 3 views of the UAV(s) (front, side, and top). Include dimensions in your sketches. Example below: 10

Hint: It is recommended to make a 3D model of the general plant of the aircraft and then use assembly features to add on different payload configurations. Sketches Peer Review Comments 11

Review your work so far Review the work you have done on the previous milestones. Revise your requirements, design decisions, and initial calculations for both aircraft types. Build a table that includes all defined parameters for your aircraft and the rationale for the definition of that parameter. Team Response Peer Review Comments 12

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Example: Scanning Aircraft: Parameter type Parameter Value Rationale Wing Aspect ratio 20 Large aspect ratio selected for reduction of induced drag Wingspan Winglets present (Y/N) No Reduce complexity, weight, and cost of development Landing gear Type Weight Empty weight MTOW Airframe dimensions Refueling Aircraft: Parameter type Parameter Value Rationale Wing Aspect ratio 20 Large aspect ratio selected for reduction of induced drag Wingspan Winglets present (Y/N) No Reduce complexity, weight, and cost of development Landing gear Type Weight Empty weight MTOW Airframe dimensions 13

Final Report The template for the final report is on Brightspace. Please use the template and follow the guidelines specified in there as you prepare your final report. Start working on your final report this week. Refine your previous milestones and start adding sections in the report that are complete. 14

Questions If you have questions about the project, please include them below. As always, for questions that likely require longer discussions, ask during class sessions or use office hours. We’re here to help! 15

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