75% Scale Airframe Design

Structural Engineering Considerations for a Scaled Weather Reconnaissance Jet

Airframe Design Specifications

✈️ TL;DR: "Can I get spec-level airframe data for a scaled model?"

Yes — with scaling considerations.

Designing a 75% scale model requires careful scaling of structural elements while maintaining functional integrity. We can adapt:

  • Material thickness reductions (scaled appropriately)
  • Spar and rib layouts optimized for smaller dimensions
  • Wing loading adjusted for reduced scale
  • G-load ratings calibrated for model size
  • Dimensions scaled proportionally

Scaled Airframe Design Conventions

🦴 Airframe Structural Layout for 75% Scale

Designing a scaled model requires proportional adjustments while maintaining structural integrity:

Component Description Material (typical) Scaled Thickness
Longerons Main axial spine beams Ti-6Al-4V / Al 7075 ~3–6 mm (75% of full-scale)
Frames / Bulkheads Ring-like sections at stress points Titanium / CFRP Reinforced Al ~2.25–4.5 mm
Stringers Secondary longitudinal support Aluminum 2024 / 7075 ~1.1–2.25 mm
Ribs (wing) Load-bearing sections with lightening holes Al 7050 or Ti-6Al-4V ~2.25–3.75 mm
Skins / Panels External cladding CFRP or titanium alloy ~1.5–3 mm
Spars (wing core) Main structural load path in wings CFRP or aluminum-titanium hybrid 3.75–9 mm

Scaled Design Load Data

Aircraft Scale Max G Load Max Wing Loading (lb/ft²) Max Payload (lbs)
YF-23 (Original) 100% +9 / -3 G ~75 lb/ft² ~20,000 lbs
WR-23 Revere 75% +5 G ~56 lb/ft² ~11,250 lbs
Scaled F-15E 75% +6.75 G ~66 lb/ft² ~17,250 lbs

Scaling Engineering Assumptions

Key considerations for 75% scale model design:

Structural Scaling

(longerons, bulkheads)

  • Thickness: 75% of full-scale
  • Material density maintained

Weight Considerations

(mass distribution)

  • Weight scales with volume (42% of original)
  • Payload capacity scaled proportionally

Aerodynamic Factors

  • Reynolds number effects accounted for
  • Control surface effectiveness calibrated

Scaling Reference Sources

Resources for scaled aircraft design:

NASA Scaling Studies

https://ntrs.nasa.gov/ (search "scaled aircraft design")

AIAA Scaling Publications

https://arc.aiaa.org/

SAE Technical Papers

Search: "structural scaling aircraft models"

Scaling-specific search terms:

"aircraft structural scaling factors" "reynolds number effects scaled models" "material thickness reduction scaled airframes" "75% scale aircraft structural design"

Engineering Philosophy for WR-23 (75% Scale)

Designing a functional 75% scale model requires balancing structural integrity with practical scaling considerations:

Scaling Strategy

Maintain material properties while reducing thickness proportionally

Optimize rib spacing for reduced dimensions while preserving strength

Structural Approach

Composite sandwich skin panels at 75% thickness

Reinforced critical joints to compensate for scale effects

Load Considerations

G-load tolerance calibrated for scaled mass and dimensions

Payload capacity adjusted to 42% of full-scale equivalent

WR‑23 Gen 1 – 75% Scale SAR Configuration

This configuration implements a 75% scale model of the YF-23 airframe, optimized for Search and Rescue (SAR) operations. Structural elements have been proportionally scaled while maintaining functional integrity for storm penetration and sensor deployment.

Attribute Specification Scaling Notes
Scale 75% of original YF-23 Linear dimensions reduced proportionally
Role Search & Rescue, Weather Recon Optimized for storm penetration
Design G-Load +5 G Calibrated for scaled mass and dimensions
Operational Ceiling 15,000 ft Sufficient for storm monitoring
Primary Materials Aluminum (7075-T6), Carbon Fiber Skin Panels Thicknesses scaled to 75%
Estimated Empty Weight ~14,745 lbs ~42% of original (mass scales with volume)
Frame Weight (Structure Only) ~12,285 lbs Proportional scaling applied
Powerplant 2 × PW545B Turbofans Adequate thrust for scaled airframe
Total Thrust ~9,600 lbf Maintained from original design
Thrust-to-Weight (Empty) ~0.65 Improved ratio due to scaling
Flight Profile Medium-altitude, storm penetration Optimized for weather monitoring