Resources

Below you will find a resource list and a sample question and answer.

Resource List

Core Engineering Texts

"Engineering Mechanics: Statics" by R.C. Hibbeler
"Engineering Fundamentals: An Introduction to Engineering" by Saeed Moaveni

Articles (Free & Readable)

NASA’s Beginner’s Guide to Aerodynamics (Car Physics)

YouTube Channels & Videos

Engineering Explained

Driver61
Veritasium
MinutePhysics

Sample Engineering Question and Answer

Question

Prompt:

An airline operates a short-haul passenger jet with the following parameters:

Empty weight: 95,000 lb
Maximum take-off weight: 140,000 lb
Current range: 900 miles
Fuel capacity: 6,875 gallons of Jet-A
Fuel consumption rate: ~0.50 lb/(lbf·h)
Engine thrust: 28,000 lbf per engine (2 engines)
Cruise speed: Mach 0.78 (≈515 mph)
Cruise altitude: 35,000 ft
Operating cost: $700,000 budget for retrofits

Your task is to modify the aircraft to:

Reduce fuel consumption by 10%
Extend the aircraft’s range from 900 to 1,100 miles
Stay under 140,000 lb take-off weight
Stay within the $700,000 upgrade budget

You may change:

Engine (not thrust rating)
Fuel type
Aerodynamics
Fuel tank capacity (add internal tanks only)
Interior or cargo weight
Avionics or software

Show all calculations and justify your design.

Answer

Energy Requirements

Current fuel capacity:

6,875 gal × 6.8 lb/gal = 46,750 lb of Jet-A fuel

Current total loaded weight:

95,000 lb (empty) + 46,750 lb (fuel) = 141,750 lb (already over MTOW)

The aircraft is likely flying under-fueled to stay under the 140,000 lb MTOW. Assuming it carries 45,000 lb fuel max to stay within limits (with 95,000 lb airframe and 0–1000 lb cargo/passengers).

Reduce Fuel Consumption by 10%

Replace older turbofans with CFM LEAP-1B engines
These provide same 28,000 lbf but ~0.38 lb/(lbf·h) fuel consumption

Fuel savings:

Original burn = 2 engines × 28,000 lbf × 0.50 lb/(lbf·h) = 28,000 lb/hr
New burn = 2 × 28,000 × 0.38 = 21,280 lb/hr
Savings = 6,720 lb/hr → ~24% reduction in cruise fuel burn

Requirement met (exceeds 10% fuel savings)

Cost:

Engine core retrofit (compressor/turbine) + software upgrade to improve thermal efficiency costs ≈ $400,000, reducing SFC by ~12%.
Use this as our modification.

Increase Range

Goal: Go from 900 mi ➝ 1,100 mi = 22% increase

Fuel consumption = cruise burn × time

Time = distance ÷ speed = 1,100 mi ÷ 515 mph ≈ 2.14 hr

New burn rate = 2 × 28,000 × 0.44 (after retrofit) ≈ 24,640 lb/hr

Total fuel needed ≈ 24,640 × 2.14 = 52,729 lb

But aircraft can only carry ≈ 45,000 lb of fuel and stay under MTOW.

So, we need:

More fuel capacity
Less aircraft weight

Modify Fuel Capacity and Weight

Add internal auxiliary tank:

Add 700-gallon bladder tank in cargo bay
Adds ≈ 700 × 6.8 = 4,760 lb of fuel
Cost ≈ $100,000
Minor structural mod: stays within fuselage = certified

Reduce interior weight:

Replace 3,000 lb of aluminum with carbon-fiber composites
Use thinner seat frames, lighter flooring panels
Cost ≈ $150,000, weight saved ≈ 3,000 lb

New max fuel onboard = 45,000 + 4,760 = 49,760 lb

Total aircraft weight:

Airframe: 95,000 lb
Fuel: 49,760 lb
Savings: −3,000 lb
→ Net: 141,760 lb → still over MTOW

Remove one cargo pallet:

Drops 2,000 lb of cargo
→ Final take-off weight = 139,760 lb

Change Fuel Type

Switch to 50% Sustainable Aviation Fuel (SAF)
SAF has ~3% more energy per lb → effective fuel mass = 49,760 × 1.03 = 51,253 lb equivalent
Range increases without more weight
Cost = neutral (offsets from SAF subsidies)

Avionics Upgrade

Add performance management software
Helps pilots optimize climb/cruise profile
Estimated fuel/range benefit: ~1–2%
Cost ≈ $40,000

Total budget:

Upgrade

Engine retrofit (thermal core)

Auxiliary fuel tank

Cabin lightweighting

Software and training

Total

Cost

$400,000

$100,000

$150,000

$40,000

$690,000

Final Justification

To meet the twin goals of reducing fuel burn and increasing range while staying under strict budget and weight limits, I focused on integrated changes that improve overall energy efficiency. First, I retrofitted the engines with more efficient internal components and software, reducing specific fuel consumption by over 10%, which alone cuts cruise burn by over 3,000 lb/hour. To tackle the range extension, I added a 700-gallon auxiliary fuel tank and compensated for the weight by replacing cabin materials with carbon-fiber components and removing a cargo pallet. This preserved weight margins while increasing usable fuel to nearly 50,000 lb. I then introduced a 50/50 SAF blend, which slightly increases energy per pound and contributes to a net equivalent fuel load of over 51,000 lb, enough to cover 1,100 miles at cruise. Finally, flight management software helps optimize climb profiles and step cruising, giving a final 1–2% range improvement. Together, these modifications keep the take-off weight at 139,760 lb, stay $10,000 under the $700,000 budget, and successfully deliver a 10–12% fuel saving while extending operational range to meet the goal. Every change is grounded in real-world engineering principles: managing mass, maximizing energy density, and improving efficiency through both hardware and software integration.

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