Aerodynamic Design of Unmanned and Scaled Supersonic ...

K. Yoshida and Y. Makino
generation SST, we used an original
configuration for evaluating the real second
generation SST.
Consequently, we can obtain that the
improvement of the L/D of a real large SST by
applying present aerodynamic design technique
is about 11% at cruise condition, compared with
the L/D of Concorde (see Table 1). Figure 10
shows estimated drag polar curves of some
configurations. We can see a remarkable
improvement on the real second generation SST.
Here “Concorde” in the Table 1 dose not mean
the exact Concorde configuration. It
ONERA-S2MA : IR Image:M=2, Re MAC =4.7×10 6 (P 0 =0.6 bar)
Flow
23.3% model
Hot-film sensors
IR camera
Transition line
Design Point:α=2°
Transition line
Off-Design Point:α=-1°
Figure 11. Transition test of NEXST-1 at ONERA
corresponds to a Concorde-like configuration without nacelle, which was designed by JAXA
according to the design philosophy described in other technical papers.
2.4 Wind Tunnel Tests
To complete the aerodynamic design of the NEXST-1 airplane, several wind tunnel tests
were conducted and the detailed results are summarized in reference [17]. In this section, the
principal results on confirming the NLF wing design concept are summarized below.
In general, it is not easy to conduct any transition measurement tests at usual blow-downtype
supersonic wind tunnels, because of the not-so-small freestream turbulence. However,
we estimated relatively lower freestream turbulence level due to continuous flow than that of
any blow-down-type supersonic tunnels. Therefore, we conducted the transition measurement
test at the supersonic closed-circuit-type tunnel of ONERA. It was called “S2MA” and had
the largest test section among several tunnels available for us. We used a wing-body
configuration test model with 23.3% scale of the NEXST-1 airplane (see Figure 11).
The infra-red (IR) image technique as well as multi-element hot-film sensors was utilized
in detecting transition location. The total pressure fluctuation measured by JAXA was about
0.29% using an unsteady pressure transducer placed on the model. Even though this value
was not so small, we clearly confirmed the rearward movement of the transition location at
the design point condition (angle of attack 2.0 degrees) as shown in Figure 11 [18]. However,
the amount of the transition movement was not the same as the predicted result by our
LSTAB code because of the freestream turbulence. Therefore, we are expecting that complete
validation will be conducted in the flight test.
3 AERODYNAMIC DESIGN OF NEXST-2 AIRPLANE
The jet-powered experimental airplane (NEXST-2 airplane) program is the second step of
developing advanced design technologies. In the aerodynamic design of the NEXST-2
airplane, the main target was placed on reducing both supersonic and subsonic drag. We
selected the YJ-69 by Teledyne as a candidate engine for the NEXST-2 airplane, because of
the limitation of cost and availability [19]. However, it had larger maximum diameter than
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