Project 1 — Power Distribution#
Design the power system for a classified prototype aerial platform, then switch sides of the table and evaluate the competing proposals as a government customer.
At a glance
Groups of 2–4. Three Gradescope submissions, 1 point each. Kicked off at Lesson 12; work days are Lessons 13 and 14. Submission 1 is due Monday 14 September at 2359; Submissions 2–3 are due Wednesday 16 September at 2359. Gradescope is authoritative for all deadlines.
The Problem#
Your team works both sides of the contracting process.
Part 1 — you are the contractor. Design a power system that energizes eight electrical loads to specification. You want a better design than the other teams.
Part 2 — you are the government evaluator. You receive the other teams’ proposals and rate them objectively with a decision matrix.
You do not see anyone else’s design until your Part 1 is submitted.
System Requirements#
The system must properly energize the following eight loads. All AC voltages are RMS and apply to a 60 Hz system. Label the loads A–H in your design, matching the proposal diagrams.
Load |
Description |
Voltage |
Specification |
|---|---|---|---|
A |
Recirculation fans |
240 Vrms |
8 kW, pf = 0.8 lagging |
B |
Fuel pumps |
240 Vrms |
12 kVA, pf = 0.6 lagging |
C |
Cabin lighting |
120 Vrms |
6 kW, pf = 0.8 lagging |
D |
Cabin fans |
120 Vrms |
5 hp, \(\eta = 88.89\%\), pf = 0.8 lagging |
E |
Auto-pilot & controls |
48 V DC |
\(R = 2\ \Omega\) |
F |
Brake power |
48 V DC |
0.75 hp, \(\eta = 85\%\) |
G |
Communications |
24 V DC |
500 W |
H |
Flight displays |
24 V DC |
25 A |
Every load type here is one you learned to handle in Lessons 6–10. Nothing in this table is new.
Constraints#
A proposed system must comply with all of the following:
All loads connected to a bus and powered to the Table 1 specifications.
Powered by a generator not exceeding 30 kW of real power during normal operation, attached to either a 240 Vrms or 120 Vrms bus.
A resistor of 0.016 Ω – 0.022 Ω between the generator and the first bus, to capture wiring losses. No cost is associated with this resistor.
Only the COTS converters listed in Table 2 of the handout may be used — in any quantity; the same catalog item may be used more than once, and each instance is priced and counted separately.
Every load, bus, and piece of conversion equipment gets its own circuit breaker.
Cost of conversion and protection must not exceed $500,000.
Volume of conversion equipment must not exceed 25 m³.
Compliance is not a score
A design that violates any constraint is not a worse design — it is a non-compliant one. Check compliance before you spend any time optimizing.
Evaluation Criteria#
The solicitation states the priority directly: cost is weighted 2× efficiency, and efficiency is weighted 2× volume. That is a ratio of 4 : 2 : 1, so:
Measure |
Ratio |
Weight |
Direction |
Normalize with |
|---|---|---|---|---|
Cost |
4 |
0.571 |
smaller is better |
\(x_{\min}/x\) |
Efficiency |
2 |
0.286 |
bigger is better |
\(x/x_{\max}\) |
Volume |
1 |
0.143 |
smaller is better |
\(x_{\min}/x\) |
Two of the three are smaller-is-better. Getting a direction backward is the fastest way to lose the Submission 2 point — see Objective 1.8.
Method#
Work backward from the loads, exactly as in Lessons 8–10:
Find the real power and current each load demands.
Group loads onto buses by voltage.
Work back through each converter: \(P_{in} = P_{out}/\eta\).
Sum at each bus, then step back to the generator.
Add the wiring-resistor loss last, using the generator current: \(P = I^2R\).
Verify the generator total is under 30 kW.
The two mistakes teams make every semester
Summing apparent power against the generator limit. The 30 kW cap is on real power. Load B is given as 12 kVA at pf = 0.6 — that is 7.2 kW real, not 12. Sum \(P\) against the limit, but size the wiring from the actual current, which follows \(S\).
Using load current in the wiring-resistor loss. That resistor sits between the generator and the first bus, so it carries the total generator current — not any individual load’s.
Deliverables#
Three Gradescope submissions, 1 point each, graded on specifications.
Submission 1 — system design (group)#
Due Monday 14 September at 2359 (before Lesson 14). Upload two files: your design and analysis as a PDF, and the completed Design Summary workbook built from the template below.
System design is easy to read, clearly labeled, and meets every design requirement. See the example bus diagram (Figure 1) in the handout below for the drawing conventions.
Mathematical analysis provided, legible, and clearly labeled.
Gradescope returns an automatic consistency report on your workbook — whether your own numbers agree with each other and with the handout’s catalogs. It is advisory feedback only; your instructors grade the two specifications above.
Submission 2 — decision matrix (group)#
Decision matrix filled out correctly. Auto-graded — trivial math errors will not earn credit. Rounding errors are fine.
Supporting analysis provided, as clearly labeled handwriting or an organized spreadsheet.
Submission 3 — engineering analysis (individual)#
Questions answered correctly with concise technical writing. Lengthy responses will not earn credit.