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Nato AVT-350 Task Group: Flight Tests With Active Flow Control Effectors on the D-90-V-2 Jet
Nato AVT-350 Task Group: Flight Tests With Active Flow Control Effectors on the D-90-V-2 Jet
What is the D-90?
What is the D-90?
The D-90 is a highly swept delta-wing jet that serves as a test platform for active flow control (AFC). The main research focus of this project is the complex AFC system integrated into the aircraft. The goal is to determine whether these effectors can match or outperform conventional control surfaces such as elevons and drag flaps.
The D-90 is equipped with surface-mounted drag flaps in addition to a pair of large elevons. The AFC system consists of two trailing-edge split Coandă-type control effectors and a pair of apex slot jets at the nose. Together, this suite of control effectors allows the D-90 to test and compare maneuverability using both types of control.
For clarity, the air supply for the AFC system comes from bleed air drawn from the jet’s powerplant, which is a small Hawk turbine.
How was it designed?
How was it designed?
By the time I was introduced to this project, the main delta-wing design had already been chosen and flown. However, the original aircraft had crashed and was no longer in service. This led to the development of the D-90 V2, which I was responsible for designing and building alongside another student.
Even though the overall shape of the aircraft remained the same, the entire internal structure was redesigned to accommodate different effectors, such as the apex effectors, and an overall new layout. The aircraft was reworked using both Fusion 360 and SolidWorks. To the right, you can see the most up-to-date CAD model of the aircraft.
The apex slot jet system was a new addition to this jet and was designed by me to be modular and easy to remove, even after the aircraft was fully assembled.
Manufacturing of the D-90
Manufacturing of the D-90
The D-90 was manufactured almost entirely in-house by me and one other student. We used a combination of different materials and techniques to bring this aircraft to life. For the structure, we primarily used a combination of fiberglass foam sheets and carbon-laminated plywood, which we vacuum-bagged in-house. The skin of the aircraft was created by vacuum-bagging and laying up fiberglass and foam within negative MDF molds. Most of the manufacturing process involved the use of a CNC router, 3D printing, and hand tools to produce various components.
Above, you can see the structure in the top left before it was layered in carbon fiber, and below, it is being test-fitted into a large MDF jig. We formally referred to this MDF jig as the "cradle," which allowed us to lay the aircraft upside down and carefully fit the pieces together during assembly. The cradle also played a crucial role in maintaining symmetric twist and dihedral while gluing the structure to the skin.
Assembling the aircraft upside down also allowed us to install components such as electronics, fuel tanks, and the AFC valve and tubing more easily. Since the aircraft is both extremely strong and lightweight, we were able to remove it during construction to test many of the critical systems before sealing the bottom.
Vacumm Bagging Example
Positive Elevon Molds (3D printed in house)
Elevon Interal Construction
Me with the D-90 rightside up for the first time!
Finished D-90
Finished D-90
This photo was taken shortly after the first D-90-V2 had been finished being painted.
Final Testing Before Flight
Final Testing Before Flight
Checking final aeroprobe calibrations using a dipstick.
Final Taxi Testing
Final Taxi Testing
Since this aircraft is a tailless, jet-powered design under 55 lbs, we had to take it to an official UAS testing range. The testing site for the D-90 V2 has consistently been in Pendleton, OR, USA. Numerous tests were conducted to ensure a safe takeoff. Many of these included high-speed taxi tests to evaluate takeoff performance. We also checked the center of gravity (CG) and adjusted the landing gear positions to optimize CG placement.
E37978E9-7D77-4DE1-A329-E12703E01D1F.MP4Flight Test Videos
Flight Test Videos
IMG_1475.MOVFirst flight with the D-90-V2 (August, 2024)
Pendleton Airport, OR
IMG_2334.MOVSecond flight with the D-90-V2 (January, 2025)
Lexington Airport, OR
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