Boeing YL-15 Scout — Primary-Source Technical Documentation Collection
The Boeing YL-15 Scout was the final single-engine, piston-powered design to emerge from Boeing's Wichita Division — a purpose-built slow-speed observation platform engineered under the USAF MX-848 program. This collection brings together the three surviving core technical references for the XL-15 prototype and YL-15 production airframe, preserved in their original form as issued by Boeing Wichita and the United States Air Force.
Aerodynamic Configuration
The YL-15 was designed around a 40-foot wingspan carrying full-span slotted flaperons — surfaces that functioned simultaneously as flaps and ailerons, dynamically dropping to maximize the lift coefficient at steep angles of attack. To preserve roll authority at full flaperon extension, Boeing integrated spoiler-ailerons on the upper wing surfaces. The fuselage was built as an aerodynamic pod suspended beneath the high wing, minimizing frontal area while providing the rear observer with an unobstructed viewing arc.
Engine & Propulsion
Power was provided by a single Lycoming O-290-7 four-cylinder, air-cooled, horizontally opposed engine rated at 125 hp, driving a McCauley 1A17/L8043 fixed-pitch aluminium alloy propeller. Thermal management relied on a custom cowl-flap layout combined with dual stainless-steel exhaust stacks fitted with integrated heat muffs for carburetor air anti-icing.
Performance Data
- Gross Weight: 2,050 lbs (930 kg)
- Empty Weight: 1,509 lbs (684 kg)
- Minimum Stall Speed (Vso): 18 mph (full flaperons deployed)
- Maximum Cruise Speed (Vc): 101 mph (88 knots)
- Never-Exceed Speed (Vne): 200 mph
- Minimum Take-off Ground Roll: 187 feet
- Rate of Climb: 628 ft/min
- Service Ceiling: 16,400 feet
- Standard Endurance: 2.25 hours (extendable to 5.5 hours with 25-gallon auxiliary tank)
Handling & Stability Engineering
The empennage was suspended on a slender, high-mounted metal tail-boom to clear the turbulent wake of the main wing. The pre-production YL-15 replaced the prototype's single tail with an inverted vertical stabilizer and twin downward-pointing rudders, keeping control surfaces inside the propeller slipstream to prevent spins. The extended tail-boom provided a long pitching moment arm to offset centre-of-gravity shifts caused by the swivelling rear observer seat. Structural testing validated safe glider-tow capability at speeds up to 160 mph.
Documents in This Collection
- Boeing Wichita Document WD-12174 — Pilot's Handbook of Flight Operating Instructions for the XL-15 Airplane (S/N 46-521, Model 451, Lycoming O-290-7). Approved by Chief, Engineering Division, Boeing Wichita.
- Technical Order AN 01-20LAA-1 (23 March 1949) — USAF Handbook of Flight Operating Instructions for the YL-15 Aircraft. Published under authority of the Secretary of the Air Force and the Chief of the Bureau of Aeronautics.
- Technical Order AN 01-20LAA-2 (10 January 1949) — USAF Handbook of Erection and Maintenance Instructions for the YL-15 Aircraft, including quick-disassembly parameters for overland truck transit. Published under authority of the Secretary of the Air Force and the Chief of the Bureau of Aeronautics.
⚠️ Regulatory Notice: Under FAA 14 CFR § 43.13 and EASA Part-M, any mechanic performing maintenance on an active aircraft must use current, manufacturer-approved revision-controlled data. This archival document does not satisfy that requirement.
This is an archival, static-copy edition fixed at its original publication date. Intended for historical reference, flight simulation, museum restoration, and educational use only. Not approved for active airworthiness maintenance under FAA 14 CFR § 43.13, EASA Part-M, or equivalent international regulations. Operators of active aircraft must use current, revision-controlled publications from the Type Certificate holder or an authorized distributor.
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