This Incredible Plane: Boeing L-15 Scout

Scout planes have played a significant role in military aviation since World War I. In fact, long before the exploits of American ace Eddie Rickenbacker and the “Hat in the Ring Squadron,” the early Army Signal Corps aviation units conducted artillery spotting and reconnaissance.

In a footnote to history, on D-Day in 1944, landing craft were modified to carry and launch spotter planes, and a Stinson L-5 was the first aircraft to land in Normandy during the invasion. 

Historically, these light artillery spotting and liaison aircraft were adapted from the civilian fleet of the time. The most famous of these, the Cessna L-19 (or O-1) Bird Dog, was a modified Cessna 170. 

However, Boeing, already deeply entrenched as the builder of choice for heavy propeller and jet bombers, in 1947 decided to take a crack at building the ultimate spotter plan—the Boeing L-15 Scout. 

Boeing engineers decided to take a clean-sheet approach to the problems faced by the U.S. Army spotter corps. The design must be able to take off and land in very short and often unprepared locations. It should be easily transported by air in the large transport aircraft of the time, such as the four-engine Boeing C-97 Stratofreighter. And it must have outstanding 360-degree vision from the cockpit to the ground below. 

This last point was a weakness of nearly all conventional high-wing monoplane designs. These placed the pilot and observer underneath the wing. However, with a conventional tail cone, elevator, and rudder, this created a significant blind spot in the flight crew’s 6 o’clock position. 

Taking a cue from the slender tail booms of helicopters from that time, the engineers decided on a conventional high-wing design from the cockpit forward mated to a high-mounted tail boom. The tail featured twin rudders that hung below the large horizontal stabilizer and elevator, although the first prototype sported a single rudder. 

This allowed the observer to enter what was essentially a glass case through two clamshell doors located under the tail boom and featured a seat that rotated 360 degrees. This arrangement allowed for nearly unrestricted 360-degree views, blocked only by the engine cowling and propeller. 

However, without a conventional tail cone, where to put the tail wheel? It appears that a tricycle landing gear configuration was not considered due to the requirement to land on unprepared surfaces, so a stout, swiveling tailwheel was located immediately under the observer’s seat. This arrangement, while a bit awkward looking on the ground, worked quite well. 

To allow for easy transport, the Boeing L-15 was designed from the outset to be folded into a narrow package that could be easily loaded into the cargo bay of a large troop transport plane. In fact, Boeing demonstrated that it could load four Scouts, 30 support troops, and all the spare parts and support equipment into a single C-97. Folding the aircraft for loading only required the removal of 16 bolts and the main landing gear wheels. 

Spotter planes are required to transit to an area of interest at cruise speed, orbit at very low speeds for long periods of time, and then land on rough or unprepared surfaces. Boeing’s approach to this problem was a fairly complex flight control system. The wings feature outboard spoilers and full-span slotted flaperons for roll control. 

The aircraft stalls at 30 knots and cruises at just below 90 knots. Power comes from a Lycoming 0-290 making 125 hp and takeoff gross weight is just over 2,000 pounds, with a 500-pound useful load. 

Endurance is just over two hours clean and a little more than five and a half hours with external fuel. One of the most incongruous features is the plane’s little centerline streamlined drop tank that would look right at home below the wings of a P-51 Mustang, but less so under the boxy L-15 Scout. 

First flight occurred in April 1947, and Boeing eventually built 12 Scouts. The first two were preproduction models labeled XL-15, and the remaining 10 were hand-built preproduction models. So confident was Boeing that it would win the contract with its revolutionary design, the company included a large spare parts inventory. 

However, it was not to be. 

Although initially receiving a contract to build 47 additional Scouts, the 1949 Army contract was canceled. The ultimate winner was the likely cheaper and simpler Cessna L-19 (later O-1) Bird Dog, which went on to a large production run and fame in Korea and Vietnam. 

By the early 1950s, Boeing was fully engrossed in revolutionizing aviation with the B-47 Stratojet, B-52 Stratofortress, and the iconic 707, so light single-engine spotter planes were a bit of an afterthought. 

So, what happened to the 12 orphan Scouts? 

Since the government had bought and paid for this amazing little fleet, they were shipped to the U.S. Fish and Wildlife Service (USFWS) in Alaska, where they served on wheels, floats, and skis for the next five years or so. Today, a single example of the type remains in flying condition. Keith Brundquist brought the fully-restored L-15 Scout to EAA Airventure Oshkosh in 2017 and went home with the Grand Champion Post-WWII and Golden Wrench awards. 

However, the story goes a bit deeper. His father, Norman, had worked on the Scouts with USFWS in Alaska and purchased the final production model. It sat outside in the elements until 2003 when Brundquist and family decided to restore it. 

And restore it they did. Every detail, right down to the contents of the first-aid kit, is present just as they were in 1949. Recently, this Scout was up for sale to the next “caretaker,” as Brundquist described himself, and hopefully will be on display at an airshow near you. There are several excellent YouTube videos featuring this remarkable little bird. 

The Boeing L-15 Scout is a perfect example of form following function and what a group of imaginative aircraft designers can develop. And one more thing: Boeing engineers designed this incredible plane in just over 30 days. Not a bad month’s work.