P16121: SAE Aero Aircraft Design & Build
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Detailed Design

Table of Contents

Team Vision for Detailed Design Phase

The detailed design phase follows the preliminary detailed design phase directly both in terms of the work that is being done and in terms of the goals. The structural design of the aircraft as well as support analysis was the main objective of the phase and a bill of material was a close second.

The team distributed itself to accomplish these tasks. Matt and Ron were tasked exclusively with structural design. Dom worked primarily on structural work with a supporting analysis role. Marc was tasked entirely with simulation and finalizing stability and control. Chris was the gatekeeper on part management and compiling the bill of materials and also assisted with the CAD work.

Our structural design is complete. There is always a benefit to iteration and revision, but at the present we have a design that we can confidently proceed with. The drawing package is not finished at this point as the number of parts of is prohibitively large and 3D modelling was a higher priority.

Prototyping, Engineering Analysis, Simulation

Aircraft design is an iterative process. The time necessary to write code and design robust simulations is a worthwhile investment in the long run because of the time saved on future repetitions and the increased accuracy and reliability of not making human errors. We have compiled a library of aerodynamic sizing code. This code has been utilized in several phases and has more substantial explanation in those places. The library here is a collection and final revision of those efforts.

Code Library

Matlab codes are the primary tool for iteration on this project. Three main codes below predict performance. The last one is of particular potency and importance.

Aerodynamic Performance

Cd0 Estimation

Aircraft Sizing, Stability, and Control

The function of the code is described in several key documents. As .pdfs: Elevator Sizing, Drag Coefficient Estimation and Stability and Control Equations.

Simulation Library

Simulations are located in the directory here. Beware, however, that many of them are quite large and if any files are missing they will not work!

Stability and Control

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Performance Revisited

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Stress Analysis

Nose Gear Von Mises Stress Distribution

Nose Gear Von Mises Stress Distribution

Nose Gear Deformation

Nose Gear Deformation

Wing Bending Moment Distribution (XFLR5)

Wing Bending Moment Distribution (XFLR5)

Spar Von Mises Stress Distribution

Spar Von Mises Stress Distribution

Tail Boom Gust Loading

Tail Boom Gust Loading

Tail Boom Von Mises Stress Distribution

Tail Boom Von Mises Stress Distribution

Drawings, Schematics, Flow Charts, Simulations

The assembly drawing package is located here.

The PDFs are collected as pdfs: A0001, A0003,A0005, A0006,A0007,A0012,A0014.

Overall View

The design process did not stop after the preliminary design review. We now have a complete design.
View of the Whole Design

View of the Whole Design

Side View

Side View

Plan View

Plan View

Tail

The tail interfaces with a square boom which is bolted to the wingbox.
View of Tail

View of Tail

View of Elevator Mechanism

View of Elevator Mechanism

View Rudder Mechanism

View Rudder Mechanism

View of Tail Fin

View of Tail Fin

View of Servo

View of Servo

Wing now incorporating Control Surfaces

The wing has received substantial revision to accommodate control surfaces.
Updated Wing

Updated Wing

View of Control Surface Details

View of Control Surface Details

Revised Landing Gear

The front landing gear was vastly over designed in the last iteration. It has been lightened. The failure in the main landing gear has been addressed.
Revised Secondary Landing Gear

Revised Secondary Landing Gear

Reinforcement of Main Landing Gear

Reinforcement of Main Landing Gear

Fuselage Changes

The fuselage has been improved on to allow for easier monokote application. The air inlets at the front are precautionary and the payload bay cover brings the aircraft into compliance with the competition rules.
Fuselage Covering

Fuselage Covering

View of Payload Cover, magnetic interface, and payload support structure

View of Payload Cover, magnetic interface, and payload support structure

Air Inlet for Cooling Electronics

Air Inlet for Cooling Electronics

Payload Support Structure

This payload bay will allow us to manufacture several different payload configurations and, by adjusting the location of the plates, make final adjustments to our center of gravity.
Payload and Support Structure

Payload and Support Structure

Bolting Solution

Because of softness of the wood, we do not want wood to be resting on threaded material. Thus we have decided that it is worth the effort to machine fasteners. These will allow us to have smooth shanks and threaded end connections.
Typical Threaded Rod

Typical Threaded Rod

Bill of Material (BOM)

The current Bill of Materials (BOM) can be found here. The document shows three separate prices for the budget; Total Cost, Estimated Expense, and Money Spent. The first section, Total Cost, would be the final cost of the airplane if all parts were purchased outright from listed suppliers. The second category, Estimated Expense, would be the estimated cost to the team after donations are factored into the budget. The final category, Money Spent, is how much money has been as of the Detailed Design Review. The first sheet of the excel file shows the summary of subsystem costs. Each subsystem has it's own sheet with a detailed description of individual parts, quantities, suppliers and estimated cost.

The Total Cost of the project is estimated to be $1,109.00 as of the Detailed Design Review.

The Estimated Actual Expense of the project is $560.04 as of the Detailed Design Review. This is considerable lower than the Total Cost because many of the expensive electrical components were donated to the team. A few of these prices, such as the payload itself, are estimated until we have a better idea of what will be done. Many different parts are combined with each other for the purposes of utilizing the most of purchased raw materials and reducing cost by purchasing supplies in bulk. The allotted budget for the project is $500. This puts the project about $60.00 over budget. The cost of fasteners is included in the estimate. More likely than not, these parts will be obtained for free or at a significantly reduced cost. For the time being the cost of these parts are included in the estimated actual price.

The total Money spent as of the Detailed Design Review is $90.00. The only parts purchased were two electrical components that are required by the competition and the accompanying shipping cost of those parts.

Shown below is a table with a cost breakdown based on each subsection of the aircraft.

Subsystem Cost Summary

Subsystem Cost Summary

Test Plans

Testing of the aircraft is a primary objective of MSD II. It is essential to go into that semester with a plan for how it will get done and ensure that the design is going to meet the testing requirements. Our testing plans for this semester are behind schedule. It should be possible to still meet our overall testing goals in the second semester. The master test plan is a living document. It outlines testing procedures and objectives. The PDF is located here.

Schedule for MSD 2

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MSD 2 Schedule in Excel for clarity

Risk Assessment

The risk assessment document has been continually updated with likelihood and severity being adjusted as the project progresses. The updated risk assessment document can be found here.

Currently the risk with the greatest intensity remains to be the inability to meet the budget constraint of $500. With the completed budget we now have a more detailed understanding of how much over budget the project is at the time of the detailed design review. We are also aware of what parts and materials are consuming the most of our budget. As discussed above, the estimated cost to complete the project is currently $560.04, or just about $60.00 over budget. When purchasing materials every attempt will be made to reduce expense, orders will be combined to combine on shipping and save on bulk prices and scrap materials will be utilized when possible. The cost of the fasteners subsection is also anticipated to decrease. We should be able to obtain many of the required nuts and bolts free of charge through MSD and/or the machine shop. This would reduce the cost of the project by over $50.00 bringing the total estimated expense down to about $505. In the event that we are unable to complete the project under the $500 limit, we are confident in our ability to secure more funding from the school and/or personal donations.

Since the start of the project the likelihood of two of the risks outlined in the initial risk assessment document have been reduced. These two risks are the "Lack of aeronautical engineering knowledge amongst team members" and "Lack of aircraft manufacturing knowledge amongst team members." Over the course of the semester the team has learned a great deal about aeronautical engineering and model aircraft manufacturing. This knowledge has come from countless hours of research on the topics as well as attending the meetings of the RIT Aero Design Club. As a result, we have reduced the likelihood of these each of these two risks from a 3 to a 2, bringing each of their seventies down from 9 to 6.

Updated Risk Assessment

Updated Risk Assessment

Design Review Materials

Detailed Presentation as Powerpoint

Detailed Design Presentation as PDF

Plans for next phase


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