This video details the design, construction, and iterative testing of a radio-controlled (RC) cargo plane built for Super Short Takeoff and Landing (SSTOL) performance. Inspired by NASA's Quiet Short-Haul Research Aircraft (QSR) and the Boeing YC-14, the project focuses on exploring advanced aerodynamic techniques rather than relying solely on high power or thrust vectoring. Key concepts investigated include the Coanda effect via upper surface blowing with top-mounted ducted fans, large flaps, a T-tail for clean airflow, leading edge slats to prevent tip stalls, and boundary layer control through forced air injection. The creator begins by modifying a standard RC airliner to demonstrate the Coanda effect, then builds a purpose-built model incorporating these features, using materials like balsa, foam, and 3D printed parts. Wind tunnel testing with tufts and smoke is employed to visualize airflow and validate design modifications. Flight tests demonstrate significant improvements in slow flight capability and reduced takeoff/landing distances, although some features like the forced air injection required refinement. The final iteration achieves impressive SSTOL performance on various surfaces. The video concludes with an attempt to launch and recover smaller drones from the cargo bay mid-flight.
Building an SSTOL RC Cargo Plane: Aerodynamic Experiments and Flight Tests
0:25 Project Goal: The creator sets out to build an RC cargo plane specifically designed for Super Short Takeoff and Landing (SSTOL) capabilities using advanced aerodynamics rather than brute force or thrust vectoring.
0:45 Inspiration: The project is inspired by real-world experimental aircraft like NASA's QSR (Quiet Short-Haul Research Aircraft) and the Boeing YC-14, known for their SSTOL features.
0:57 Visiting the YC-14: The creator visited the Pima Air & Space Museum to study the actual YC-14, noting its aerodynamic features like upper surface blowing, large flaps, and T-tail.
1:23 Coanda Effect: A core concept explored is the Coanda effect, where airflow attaches to a curved surface (like a flap) due to viscosity and the pressure gradient created by the air being blown over it, generating significant lift.
1:31 Initial Test Platform: An RC airliner is modified by placing the engines on top of the wings to test the upper surface blowing concept (Coanda effect).
1:48 Initial Airliner Test Flight: The modified airliner is tested (0:01:48), showing different behavior but struggling to take off due to insufficient elevator authority (pitch control).
3:11 Modifying the Airliner: The airliner is modified with a larger elevator (3:34) to improve pitch authority for better takeoff rotation.
3:44 Second Airliner Test Flight: The modified airliner with the larger elevator takes off in a fraction of the distance (3:58), demonstrating improved performance, but the wing shows stalling issues.
4:23 Purpose-Built Design: Recognizing the limitations of modifying an airliner, the creator decides to design and build a purpose-built RC cargo plane specifically for the experiment, using CAD (4:27).
4:51 Construction Details: The custom plane uses traditional balsa wood framing, foam sheeting for skin (5:01), 3D printed leading edges (5:12), and a standard cargo plane fuselage design with a T-tail (5:21-5:30).
5:33 3D Printed Components: Various parts like hinges, ailerons (5:36), and flaps (5:51) are 3D printed.
5:51 First Flight Test (Basic Config): The custom plane is tested with top-mounted fans and flaps (5:57). Despite darkness (6:20), the plane flies very slowly (6:50, 7:03) but eventually crashes due to an aggressive takeoff attempt causing the wing to stall (7:17).
7:26 Post-Crash Modifications: Based on the crash, the wing's angle of incidence is increased, and leading edge slats (7:58, 9:53) are added to improve airflow attachment at high angles of attack and prevent tip stalls.
8:22 Wind Tunnel Testing: A simple wind tunnel (8:22) is used with tissue paper tufts (8:15) and smoke (10:13) to visualize airflow separation (stall) and demonstrate how the slats keep the flow attached (9:40-9:46, 11:04).
10:02 Airflow Augmentation Concept: The creator explores adding forced air injection ("airflow augmentator" / "supercharger") across the wing surface to actively control the boundary layer and prevent stalls, inspired by older research videos (17:45).
18:12 Forced Air Implementation: A ducted fan is integrated into the wing, blowing air through internal channels and out over the top surface via vents (18:39, 19:18).
19:30 Wind Tunnel Test (Forced Air): Wind tunnel tests with smoke demonstrate how the forced air injection keeps the airflow attached to the wing at extremely high angles of attack, which would normally cause a stall (20:18-20:28).
20:58 Flight Test (Slats + Forced Air): The plane with slats and forced air is tested (21:17). Takeoff is very short (21:17), control is rock steady even near stall speeds (21:25), and stall characteristics are more benign (21:56), though there might be some power reduction from the nozzles (21:36). An ESC issue occurs (22:14).
23:31 Removing Forced Air Nozzles: The forced air nozzles are removed due to potential power restriction and the belief that upper surface blowing is still effective without them.
24:22 Flight Test (Slats, No Forced Air Nozzles): Without the restrictive nozzles, takeoff distance is even shorter, power is improved, and the plane still exhibits excellent slow flight and stable control (24:22).
24:44 Rough Field Performance: The plane successfully performs takeoffs and landings on a challenging, bumpy dirt road (24:46, 25:44), highlighting its SSTOL capability and the effectiveness of the springy landing gear (26:27).
27:24 High Performance Takeoff: Demonstrates a "high performance" takeoff where the tail is held while engines spool up; the Coanda effect generates enough lift to lift the main gear before the nose gear (27:29).
28:21 Drone Drop/Catch Attempt: An attempt is made to fly small FPV drones (Beta FPV Air75/Meteor 75 Pro) into the cargo bay of the flying plane (28:30), with limited success but demonstrating the drones' durability (29:28).
29:48 Project Conclusion: The creator expresses satisfaction with the plane's performance, highlighting the success of the aerodynamic features (flaps, slats, upper surface blowing) in achieving slow flight and SSTOL without relying on excessive power or thrust vectoring.
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